WorldWideScience

Sample records for valley fill glacial

  1. The glacially overdeepened trough of the Salzach Valley, Austria: Bedrock geometry and sedimentary fill of a major Alpine subglacial basin

    Science.gov (United States)

    Pomper, Johannes; Salcher, Bernhard C.; Eichkitz, Christoph; Prasicek, Günther; Lang, Andreas; Lindner, Martin; Götz, Joachim

    2017-10-01

    Overdeepened valleys are unambiguous features of glacially sculpted landscapes. They result from erosion at the bed of the glacier and their size and shape is determined by ice dynamics and the characteristics of the underlying bedrock. Major overdeepened valleys representing vertical bedrock erosion of several hundreds of meters are characteristic features of many trunk valleys in the formerly glaciated parts of the Alpine mountain belt. The thick sedimentary fill usually hinders attempts to unravel bedrock geometry, formation history and fill characteristics. Based on reflection seismic data and core-logs from multiple deep drillings we construct a detailed bedrock model of the Lower Salzach Valley trough, one of the largest overdeepened valleys in the European Alps. The analysed overdeepened structure characterized by a strongly undulating topography. Two reaches of enhanced erosion can be identified and are suggested to be related to variations in bedrock erodibility and a triple glacier confluence. The sedimentary fill shows clear characteristics of rapid infilling and subaqueous fan delta deposits indicate a strong influence of tributary streams. Associated surface lowering of the valley floor had a major impact on tributary stream incision but also on the available ice accumulation area at subsequent glaciations. The extent to which fills of earlier glaciations have been preserved from erosion during the last glacial maximum remains ambiguous and demands further exploration. To our knowledge the presented bedrock model is one of the best defined of any major overdeepened trunk valley.

  2. Better building of valley fills

    Energy Technology Data Exchange (ETDEWEB)

    Chironis, N.P.

    1980-03-01

    Current US regulations for building valley fills or head of hollow fills to hold excess spoil resulting from contour mining are meeting with considerable opposition, particularly from operators in steep-slope areas. An alternative method has been submitted to the Office of Surface Mining by Virgina. Known as the zoned concept method, it has already been used successfully in building water-holding dams and coal refuse embankments on sloping terrain. The ways in which drainage and seepage are managed are described.

  3. Glacial geology of the upper Wairau Valley, Marlborough, New Zealand

    International Nuclear Information System (INIS)

    McCalpin, J.P.

    1992-01-01

    Late Pleistocene glaciers in the upper Wairau Valley deposited four groups of moraines inferred to represent one Waimean ice advance, two Otiran ice advances, and an advance of early Aranuian age. The Waimean and early Otiran glaciers advanced into Tarndale Valley, deposited terminal moraines, and shed outwash down both the Alma River and Travellers Valley. The middle Otiran glacier terminated in northern Tarndale Valley and shed outwash from the southern part of its terminus down the Alma River. The north side of the terminus abutted a large ice-dammed lake in the Wairau Gorge, and fan-deltas graded to an old shore level at an elevation of 1040 m. Well-preserved moraines at the mouths of four glaciated tributaries may be middle Otiran recessional, or late Otiran terminal moraines. The latest ice advance extended 11 km down the upper Wairau Valley and deposited a subdued moraine at Island Gully. The composite chronology of the latest glacial advance based on 10 radiocarbon ages suggests it occurred between about 9.5 and 10.2 ka. This age span is similar to that of early Aranuian glacial advances dated by other workers in the Southern Alps, and may reflect Younger Dryas cooling. (author). 22 refs., 10 figs., 3 tabs

  4. Hydrogeology of Valley-Fill Aquifers and Adjacent Areas in Eastern Chemung County, New York

    Science.gov (United States)

    Heisig, Paul M.

    2015-10-19

    The extent, hydrogeologic framework, and potential well yields of valley-fill aquifers within a 151-square-mile area of eastern Chemung County, New York, were investigated, and the upland distribution of till thickness over bedrock was characterized. The hydrogeologic framework of these valleyfill aquifers was interpreted from multiple sources of surficial and subsurface data and an interpretation of the origin of the glacial deposits, particularly during retreat of glacial ice from the region. Potential yields of screened wells are based on the hydrogeologic framework interpretation and existing well-yield data, most of which are from wells finished with open-ended well casing.

  5. 30 CFR 817.72 - Disposal of excess spoil: Valley fill/head-of-hollow fills.

    Science.gov (United States)

    2010-07-01

    ... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.72 Disposal of excess spoil: Valley fill/head-of-hollow fills.... Uncontrolled surface drainage may not be directed over the outslope of the fill. (2) Runoff from areas above the fill and runoff from the surface of the fill shall be diverted into stabilized diversion channels...

  6. Geohydrology of the valley-fill aquifer in the Corning area, Steuben County, New York

    Science.gov (United States)

    Miller, Todd S.; Belli, J.L.; Allen, R.V.

    1982-01-01

    This report is the seventh in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Steuben County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, potentiometric-surface elevations, and land use. The valley-fill deposits consist of alluvial silt, sand, and gravel, glacial-outwash (sand and gravel), till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities, whereas the till and silt deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel along the valley margin. Artesian conditions are found locally in sand and gravel confined under silt and clay in the middle of the valley. Recharge occurs nearly everywhere on the valley floor, but principally along the margin of the valley, where highly permeable land surface conditions exist, and runoff from the hillsides is concentrated. The use of land overlying the aquifer is a mixture of residential, commercial, agricultural, and industrial uses. (USGS)

  7. Optimal decentralized valley-filling charging strategy for electric vehicles

    International Nuclear Information System (INIS)

    Zhang, Kangkang; Xu, Liangfei; Ouyang, Minggao; Wang, Hewu; Lu, Languang; Li, Jianqiu; Li, Zhe

    2014-01-01

    Highlights: • An implementable charging strategy is developed for electric vehicles connected to a grid. • A two-dimensional pricing scheme is proposed to coordinate charging behaviors. • The strategy effectively works in decentralized way but achieves the systematic valley filling. • The strategy allows device-level charging autonomy, and does not require a bidirectional communication/control network. • The strategy can self-correct when confronted with adverse factors. - Abstract: Uncoordinated charging load of electric vehicles (EVs) increases the peak load of the power grid, thereby increasing the cost of electricity generation. The valley-filling charging scenario offers a cheaper alternative. This study proposes a novel decentralized valley-filling charging strategy, in which a day-ahead pricing scheme is designed by solving a minimum-cost optimization problem. The pricing scheme can be broadcasted to EV owners, and the individual charging behaviors can be indirectly coordinated. EV owners respond to the pricing scheme by autonomously optimizing their individual charge patterns. This device-level response induces a valley-filling effect in the grid at the system level. The proposed strategy offers three advantages: coordination (by the valley-filling effect), practicality (no requirement for a bidirectional communication/control network between the grid and EV owners), and autonomy (user control of EV charge patterns). The proposed strategy is validated in simulations of typical scenarios in Beijing, China. According to the results, the strategy (1) effectively achieves the valley-filling charging effect at 28% less generation cost than the uncoordinated charging strategy, (2) is robust to several potential affecters of the valley-filling effect, such as (system-level) inaccurate parameter estimation and (device-level) response capability and willingness (which cause less than 2% deviation in the minimal generation cost), and (3) is compatible with

  8. Post-glacial landform evolution in the middle Satluj River valley, India

    Indian Academy of Sciences (India)

    incision. Climatically, the event corresponds to the post-glacial strengthened Indian summer monsoon. (ISM). ... middle Satluj valley extreme events shape the land- scape besides ...... District Disaster Management Authority (DDMA), Kinnaur,.

  9. Geohydrology of the valley-fill aquifer in the Jamestown area, Chautauqua County, New York

    Science.gov (United States)

    Anderson, H.R.; Stelz, W.G.; Belli, J.L.; Allen, R.V.

    1982-01-01

    This report is the sixth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Chautauqua County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, potentiometric-surface elevations and land use. The valley-fill deposits consist of alluvial silt and sand, glacial-outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt and clay deposits have relatively low permeabilities. Water-table conditions prevail in u nconfined sand and gravel beds along the valley margin. Artesian conditions prevail in confined sand and gravel buried under silt and clay in the middle of the valley. Recharge occurs mainly along the margin of the valley, where the land surface is highly permeable and runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly agricultural and residential with lesser amounts of commercial and industrial uses. (USGS)

  10. A mechanism for overdeepenings of glacial valleys and fjords

    OpenAIRE

    Herman F.; Beaud F.; Champagnac J.-D.; Lemieux J.-M.; Sternai P.

    2011-01-01

    Most glacial erosion models assume that erosion rates are proportional to ice sliding velocity. While recent studies have shown that water plays a major role in modulating sliding velocities the impact it might have on erosion rates is still unclear. Here we incorporate subglacial hydrology into a glacial erosion model that is based on a sliding rule. Our results explicitly highlight that adding subglacial hydrology has profound impacts on the temporal and spatial patterns of glacial erosion....

  11. Luminescence dating of paleolake deltas and glacial deposits in Garwood Valley, Antarctica: Implications for climate, Ross ice sheet dynamics, and paleolake duration

    Science.gov (United States)

    Levy, Joseph S.; Rittenour, Tammy M.; Fountain, Andrew G.; O'Connor, Jim E.

    2017-01-01

    The formation of perched deltas and other lacustrine deposits in the McMurdo Dry Valleys of Antarctica is widely considered to be evidence of valley-filling lakes dammed by the grounded Ross Sea ice sheet during the local Last Glacial Maximum, with lake drainage interpreted as a record of grounding line retreat. We used luminescence dating to determine the age of paleolake deltas and glacial tills in Garwood Valley, a coastal dry valley that opens to the Ross Sea. Luminescence ages are stratigraphically consistent with radiocarbon results from algal mats within the same delta deposits but suggest radiocarbon dates from lacustrine carbonates may overestimate deposit ages by thousands of years. Results suggest that late Holocene delta deposition into paleolake Howard in Garwood Valley persisted until ca. 3.5 ka. This is significantly younger than the date when grounded ice is thought to have retreated from the Ross Sea. Our evidence suggests that the local, stranded ice-cored till topography in Garwood Valley, rather than regional ice-sheet dynamics, may have controlled lake levels for some McMurdo Dry Valleys paleolakes. Age control from the supraglacial Ross Sea drift suggests grounding and up-valley advance of the Ross Sea ice sheet into Garwood valley during marine oxygen isotope stage (MIS) 4 (71–78 ka) and the local Last Glacial Maximum (9–10 ka). This work demonstrates the power of combining luminescence dating with existing radiocarbon data sets to improve understanding of the relationships among paleolake formation, glacial position, and stream discharge in response to climate change.

  12. Hydrogeology of the Ramapo River-Woodbury Creek valley-fill aquifer system and adjacent areas in eastern Orange County, New York

    Science.gov (United States)

    Heisig, Paul M.

    2015-01-01

    The hydrogeology of the valley-fill aquifer system and surrounding watershed areas was investigated within a 23-mile long, fault-controlled valley in eastern Orange County, New York. Glacial deposits form a divide within the valley that is drained to the north by Woodbury Creek and is drained to the south by the Ramapo River. Surficial geology, extent and saturated thickness of sand and gravel aquifers, extent of confining units, bedrock-surface elevation beneath valleys, major lineaments, and the locations of wells for which records are available were delineated on an interactive map.

  13. Gigantic landslides versus glacial deposits: on origin of large hummock deposits in Alai Valley, Northern Pamir

    Science.gov (United States)

    Reznichenko, Natalya

    2015-04-01

    As glaciers are sensitive to local climate, their moraines position and ages are used to infer past climates and glacier dynamics. These chronologies are only valid if all dated moraines are formed as the result of climatically driven advance and subsequent retreat. Hence, any accurate palaeoenvironmental reconstruction requires thorough identification of the landform genesis by complex approach including geomorphological, sedimentological and structural landform investigation. Here are presented the implication of such approach for the reconstruction of the mega-hummocky deposits formation both of glacial and landslide origin in the glaciated Alai Valley of the Northern Pamir with further discussion on these and similar deposits validity for palaeoclimatic reconstructions. The Tibetan Plateau valleys are the largest glaciated regions beyond the ice sheets with high potential to provide the best geological record of glacial chronologies and, however, with higher probabilities of the numerous rock avalanche deposits including those that were initially considered of glacial origin (Hewitt, 1999). The Alai Valley is the largest intermountain depression in the upper reaches of the Amudarja River basin that has captured numerous unidentified extensive hummocky deposits descending from the Zaalai Range of Northern Pamir, covering area in more than 800 km2. Such vast hummocky deposits are usually could be formed either: 1) glacially by rapid glacial retreat due to the climate signal or triggered a-climatically glacial changes, such as glacial surge or landslide impact, or 2) during the landslide emplacement. Combination of sediment tests on agglomerates forming only in rock avalanche material (Reznichenko et al., 2012) and detailed geomorphological and sedimentological descriptions of these deposits allowed reconstructing the glacial deposition in the Koman and Lenin glacial catchments with identification of two gigantic rock avalanches and their relation to this glacial

  14. Geohydrology of the valley-fill aquifer in the Ramapo and Mahwah rivers area, Rockland County, New York

    Science.gov (United States)

    Moore, Richard Bridge; Cadwell, D.H.; Stelz, W.G.; Belli, J.L.

    1982-01-01

    This report is the eighth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Rockland County. The maps include surficial geology, geologic sections, water-infiltration potential of soil zone, aquifer thickness, water-table elevations, well yields, and land use. The valley-fill deposits consists of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities, whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel along the Ramapo River valley and much of the Mahwah River valley. Artesian conditions prevail in confined sand and gravel buried under silt and clay and till in parts of the Mahway valley. The aquifer is recharged throughout, where the land surface is most permeable and is greatest along the margin of the valley, where runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly commercial, agricultural and residential, with lesser industrial uses. (USGS)

  15. Intelligent electric vehicle charging: Rethinking the valley-fill

    Science.gov (United States)

    Valentine, Keenan; Temple, William G.; Zhang, K. Max

    This study proposes an intelligent PEV charging scheme that significantly reduces power system cost while maintaining reliability compared to the widely discussed valley-fill method of aggregated charging in the early morning. This study considers optimal PEV integration into the New York Independent System Operator's (NYISO) day-ahead and real-time wholesale energy markets for 21 days in June, July, and August of 2006, a record-setting summer for peak load. NYISO market and load data is used to develop a statistical Locational Marginal Price (LMP) and wholesale energy cost model. This model considers the high cost of ramping generators at peak-load and the traditional cost of steady-state operation, resulting in a framework with two competing cost objectives. Results show that intelligent charging assigns roughly 80% of PEV load to valley hours to take advantage of low steady-state cost, while placing the remaining 20% equally at shoulder and peak hours to reduce ramping cost. Compared to unregulated PEV charging, intelligent charging reduces system cost by 5-16%; a 4-9% improvement over the flat valley-fill approach. Moreover, a Charge Flexibility Constraint (CFC), independent of market modeling, is constructed from a vehicle-at-home profile and the mixture of Level 1 and Level 2 charging infrastructure. The CFC is found to severely restrict the ability to charge vehicles during the morning load valley. This study further shows that adding more Level 2 chargers without regulating PEV charging will significantly increase wholesale energy cost. Utilizing the proposed intelligent PEV charging method, there is a noticeable reduction in system cost if the penetration of Level 2 chargers is increased from 70/30 to 50/50 (Level 1/Level 2). However, the system benefit is drastically diminished for higher penetrations of Level 2 chargers.

  16. Quantitative Morphometric Analysis of Terrestrial Glacial Valleys and the Application to Mars

    Science.gov (United States)

    Allred, Kory

    Although the current climate on Mars is very cold and dry, it is generally accepted that the past environments on the planet were very different. Paleo-environments may have been warm and wet with oceans and rivers. And there is abundant evidence of water ice and glaciers on the surface as well. However, much of that comes from visual interpretation of imagery and other remote sensing data. For example, some of the characteristics that have been utilized to distinguish glacial forms are the presence of landscape features that appear similar to terrestrial glacial landforms, constraining surrounding topography, evidence of flow, orientation, elevation and valley shape. The main purpose of this dissertation is to develop a model that uses quantitative variables extracted from elevation data that can accurately categorize a valley basin as either glacial or non-glacial. The application of this model will limit the inherent subjectivity of image analysis by human interpretation. The model developed uses hypsometric attributes (elevation-area relationship), a newly defined variable similar to the equilibrium line altitude for an alpine glacier, and two neighborhood search functions intended to describe the valley cross-sectional curvature, all based on a digital elevation model (DEM) of a region. The classification model uses data-mining techniques trained on several terrestrial mountain ranges in varied geologic and geographic settings. It was applied to a select set of previously catalogued locations on Mars that resemble terrestrial glaciers. The results suggest that the landforms do have a glacial origin, thus supporting much of the previous research that has identified the glacial landforms. This implies that the paleo-environment of Mars was at least episodically cold and wet, probably during a period of increased planetary obliquity. Furthermore, the results of this research and the implications thereof add to the body of knowledge for the current and past

  17. Catastrophic valley fills record large Himalayan earthquakes, Pokhara, Nepal

    Science.gov (United States)

    Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Hoelzmann, Philipp; Adhikari, Basanta R.; Fort, Monique; Korup, Oliver

    2017-12-01

    Uncertain timing and magnitudes of past mega-earthquakes continue to confound seismic risk appraisals in the Himalayas. Telltale traces of surface ruptures are rare, while fault trenches document several events at best, so that additional proxies of strong ground motion are needed to complement the paleoseismological record. We study Nepal's Pokhara basin, which has the largest and most extensively dated archive of earthquake-triggered valley fills in the Himalayas. These sediments form a 148-km2 fan that issues from the steep Seti Khola gorge in the Annapurna Massif, invading and plugging 15 tributary valleys with tens of meters of debris, and impounding several lakes. Nearly a dozen new radiocarbon ages corroborate at least three episodes of catastrophic sedimentation on the fan between ∼700 and ∼1700 AD, coinciding with great earthquakes in ∼1100, 1255, and 1344 AD, and emplacing roughly >5 km3 of debris that forms the Pokhara Formation. We offer a first systematic sedimentological study of this formation, revealing four lithofacies characterized by thick sequences of mid-fan fluvial conglomerates, debris-flow beds, and fan-marginal slackwater deposits. New geochemical provenance analyses reveal that these upstream dipping deposits of Higher Himalayan origin contain lenses of locally derived river clasts that mark time gaps between at least three major sediment pulses that buried different parts of the fan. The spatial pattern of 14C dates across the fan and the provenance data are key to distinguishing these individual sediment pulses, as these are not evident from their sedimentology alone. Our study demonstrates how geomorphic and sedimentary evidence of catastrophic valley infill can help to independently verify and augment paleoseismological fault-trench records of great Himalayan earthquakes, while offering unparalleled insights into their long-term geomorphic impacts on major drainage basins.

  18. Using Seismic Refraction and Ground Penetrating Radar (GPR) to Characterize the Valley Fill in Beaver Meadows, Rocky Mountain National Park

    Science.gov (United States)

    Kramer, N.; Harry, D. L.; Wohl, E. E.

    2010-12-01

    This study is one of the first to use near surface geophysical techniques to characterize the subsurface stratigraphy in a high alpine, low gradient valley with a past glacial history and to obtain a preliminary grasp on the impact of Holocene beaver activity. Approximately 1 km of seismic refraction data and 5 km of GPR data were collected in Beaver Meadows, Rocky Mountain National Park. An asymmetric wedge of sediment ranging in depth from 0-20 m transverse to the valley profile was identified using seismic refraction. Complementary analysis of the GPR data suggests that the valley fill can be subdivided into till deposited during the Pleistocene glaciations and alluvium deposited during the Holocene. Two main facies were identified in the GPR profiles through pattern recognition. Facie Fd, which consists of chaotic discontinuous reflectors with an abundance of diffractions, is interpreted to be glacial till. Facie Fc, which is a combination of packages of complex slightly continuous reflectors interfingered with continuous horizontal to subhorizontal reflectors, is interpreted to be post-glacial alluvium and includes overbank, pond and in-channel deposits. Fc consistently overlies Fd throughout the study area and is no more than 7 m thick in the middle of the valley. The thickness of Holocene sedimentation (beaver dams, a high abundance of fine sediment including silts and clays, historical records of beavers, and the name "Beaver Meadows" all suggest that Holocene beaver activity played a large role in sediment accumulation at this site, despite the lack of surficial relict beaver dams containing wood.

  19. The late Pleistocene glacial sequence in the middle Maruia valley, southeast Nelson, New Zealand

    International Nuclear Information System (INIS)

    Mabin, M.C.G.

    1983-01-01

    Glacial and fluvioglacial landforms and deposits preserved in the middle reaches of the Maruia valley, southeast Nelson, New Zealand, record the activity of the Maruia glacier during the late Pleistocene Otira Glaciation. Five advances are recognised, from oldest to youngest: Creighton 1, 2, 3, and the Reid Stream 1, 2 advances. There was an interstadial interval between the Creighton 3 and Reid Stream 1 advances. The Reid Stream 1 advance occurred shortly after 14 800 years B.P. (NZ536, old T/sub 0.5/). (auths)

  20. Geohydrology of the valley-fill aquifer in the Endicott-Johnson City area, Broome County, New York

    Science.gov (United States)

    Holecek, Thomas J.; Randall, A.D.; Belli, J.L.; Allen, R.V.

    1982-01-01

    This report is the tenth in a series of 11 map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on five maps at 1:24,000 scale. Together, the maps provide a comprehensive overview of a major valley-fill aquifer in southwestern Broome County. The maps include surficial geology, geologic sections, aquifer thickness, water-infiltration potential of soil zone, potentiometric-surface altitude, and land use. The valley-fill deposits consist of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions are found in unconfined sand and gravel, whereas artesian conditions prevail within sand and gravel confined by silty deposits. Recharge occurs over the entire surface of the aquifer, due to permeable land-surface conditions, but is greatest along the margin of the valley, where runoff from the hillsides is concentrated, and near streams. The use of land overlying the aquifer is predominantly commercial and residential with lesser amounts of agricultural and industrial uses. (USGS)

  1. Geohydrology of the valley-fill aquifer in the South Fallsburgh-Woodbourne area, Sullivan County, New York

    Science.gov (United States)

    Anderson, H.R.; Dineen, R.J.; Stelz, W.G.; Belli, J.L.

    1982-01-01

    This report is the ninth in a series of map sets depicting geohydrologic conditions in selected aquifers in upstate New York. Geohydrologic data are compiled on six maps at 1:24,000 scale. Together the maps provide a comprehensive overview of a major valley-fill aquifer in southeastern Sullivan County. The maps include surficial geology, geologic sections, aquifer thickness, water-infiltration potential of soil zone, potentiometric surface elevations, well yields, and land use. The valley-fill deposits consist of alluvial silt and sand, glacial outwash (sand and gravel), ice-contact sand and gravel, till, and lacustrine silt and clay. The sand and gravel beds have relatively high permeabilities whereas the till, silt, and clay deposits have relatively low permeabilities. Water-table conditions prevail in unconfined sand and gravel whereas artesian conditions prevail within sand and gravel confined by silty deposits. The aquifer is recharged throughout, where the land surface is most permeable and is greatest along the margin of the valley, where runoff from the hillsides is concentrated. The use of land overlying the aquifer is predominantly commercial, agricultural, and residential with lesser industrial uses. (USGS)

  2. Latest Pleistocene and Holocene glacial events in the Colonia valley, Northern Patagonia Icefield, southern Chile

    Science.gov (United States)

    Nimick, David A.; Mcgrath, Daniel; Mahan, Shannon; Friesen, Beverly A.; Leidich, Jonathan

    2016-01-01

    The Northern Patagonia Icefield (NPI) is the primary glaciated terrain worldwide at its latitude (46.5–47.5°S), and constraining its glacial history provides unique information for reconstructing Southern Hemisphere paleoclimate. The Colonia Glacier is the largest outlet glacier draining the eastern NPI. Ages were determined using dendrochronology, lichenometry, radiocarbon, cosmogenic 10Be and optically stimulated luminescence. Dated moraines in the Colonia valley defined advances at 13.2 ± 0.95, 11.0 ± 0.47 and 4.96 ± 0.21 ka, with the last being the first constraint on the onset of Neoglaciation for the eastern NPI from a directly dated landform. Dating in the tributary Cachet valley, which contains an ice-dammed lake during periods of Colonia Glacier expansion, defined an advance at ca. 2.95 ± 0.21 ka, periods of advancement at 810 ± 49 cal a BP and 245 ± 13 cal a BP, and retreat during the intervening periods. Recent Colonia Glacier thinning, which began in the late 1800s, opened a lower-elevation outlet channel for Lago Cachet Dos in ca. 1960. Our data provide the most comprehensive set of Latest Pleistocene and Holocene ages for a single NPI outlet glacier and expand previously developed NPI glacial chronologies.

  3. Sedimentary architecture and chronostratigraphy of a late Quaternary incised-valley fill: A case study of the late Middle and Late Pleistocene Rhine system in the Netherlands

    Science.gov (United States)

    Peeters, J.; Busschers, F. S.; Stouthamer, E.; Bosch, J. H. A.; Van den Berg, M. W.; Wallinga, J.; Versendaal, A. J.; Bunnik, F. P. M.; Middelkoop, H.

    2016-01-01

    This paper describes the sedimentary architecture, chronostratigraphy and palaeogeography of the late Middle and Late Pleistocene (Marine Isotope Stage/MIS 6-2) incised Rhine-valley fill in the central Netherlands based on six geological transects, luminescence dating, biostratigraphical data and a 3D geological model. The incised-valley fill consists of a ca. 50 m thick and 10-20 km wide sand-dominated succession and includes a well-developed sequence dating from the Last Interglacial: known as the Eemian in northwest Europe. The lower part of the valley fill contains coarse-grained fluvio-glacial and fluvial Rhine sediments that were deposited under Late Saalian (MIS 6) cold-climatic periglacial conditions and during the transition into the warm Eemian interglacial (MIS 5e-d). This unit is overlain by fine-grained fresh-water flood-basin deposits, which are transgressed by a fine-grained estuarine unit that formed during marine high-stand. This ca. 10 m thick sequence reflects gradual drowning of the Eemian interglacial fluvial Rhine system and transformation into an estuary due to relative sea-level rise. The chronological data suggests a delay in timing of regional Eemian interglacial transgression and sea-level high-stand of several thousand years, when compared to eustatic sea-level. As a result of this glacio-isostatic controlled delay, formation of the interglacial lower deltaic system took only place for a relative short period of time: progradation was therefore limited. During the cooler Weichselian Early Glacial period (MIS 5d-a) deposition of deltaic sediments continued and extensive westward progradation of the Rhine system occurred. Major parts of the Eemian and Weichselian Early Glacial deposits were eroded and buried as a result of sea-level lowering and climate cooling during the early Middle Weichselian (MIS 4-3). Near complete sedimentary preservation occurred along the margins of the incised valley allowing the detailed reconstruction presented

  4. Evidence for slow late-glacial ice retreat in the upper Rangitata Valley, South Island, New Zealand

    Science.gov (United States)

    Shulmeister, J.; Fink, D.; Winkler, S.; Thackray, G. D.; Borsellino, R.; Hemmingsen, M.; Rittenour, T. M.

    2018-04-01

    A suite of cosmogenic radionuclide ages taken from boulders on lateral and latero-terminal moraines in the Rangitata Valley, eastern South Island, New Zealand demonstrates that relatively thick ice occupied valley reaches inland of the Rangitata Gorge until c. 21 ka. Thereafter ice began to thin, and by c. 17 ka it had retreated 33 km up-valley of the Rangitata Gorge to the Butler-Brabazon Downs, a structurally created basin in the upper Rangitata Valley. Despite its magnitude, this retreat represents a minor ice volume reduction from 21 ka to 17 ka, and numerous lateral moraines preserved suggest a relatively gradual retreat over that 4 ka period. In contrast to records from adjacent valleys, there is no evidence for an ice-collapse at c. 18 ka. We argue that the Rangitata record constitutes a more direct record of glacial response to deglacial climate than other records where glacial dynamics were influenced by proglacial lake development, such as the Rakaia Valley to the North and the major valleys in the Mackenzie Basin to the south-west. Our data supports the concept of a gradual warming during the early deglaciation in the South Island New Zealand.

  5. Integrated hazard assessment of Cirenmaco glacial lake in Zhangzangbo valley, Central Himalayas

    Science.gov (United States)

    Wang, Weicai; Gao, Yang; Iribarren Anacona, Pablo; Lei, Yanbin; Xiang, Yang; Zhang, Guoqing; Li, Shenghai; Lu, Anxin

    2018-04-01

    Glacial lake outburst floods (GLOFs) have recently become one of the primary natural hazards in the Himalayas. There is therefore an urgent need to assess GLOF hazards in the region. Cirenmaco, a moraine-dammed lake located in the upstream portion of Zhangzangbo valley, Central Himalayas, has received public attention after its damaging 1981 outburst flood. Here, by combining remote sensing methods, bathymetric survey and 2D hydraulic modeling, we assessed the hazard posed by Cirenmaco in its current status. Inter-annual variation of Cirenmaco lake area indicates a rapid lake expansion from 0.10 ± 0.08 km2 in 1988 to 0.39 ± 0.04 km2 in 2013. Bathymetric survey shows the maximum water depth of the lake in 2012 was 115 ± 2 m and the lake volume was calculated to be 1.8 × 107 m3. Field geomorphic analysis shows that Cirenmaco glacial lake is prone to GLOFs as mass movements and ice and snow avalanches can impact the lake and the melting of the dead ice in the moraine can lower the dam level. HEC-RAS 2D model was then used to simulate moraine dam failure of the Cirenmaco and assess GLOF impacts downstream. Reconstruction of Cirenmaco 1981 GLOF shows that HEC-RAS can produce reasonable flood extent and water depth, thus demonstrate its ability to effectively model complex GLOFs. GLOF modeling results presented can be used as a basis for the implementation of disaster prevention and mitigation measures. As a case study, this work shows how we can integrate different methods to GLOF hazard assessment.

  6. Glacial and periglacial environment monitoring in Aosta Valley - Northwestern Italian Alps

    Science.gov (United States)

    Motta, Elena; Cremonese, Edoardo; Morra di Cella, Umberto; Pogliotti, Paolo; Vagliasindi, Marco

    2010-05-01

    Aosta Valley is a small alpine region of about 3.300 km2 located in the NW Italy, on the southern side of the Alps and surrounded by the highest Alpine peaks such as Mont Blanc (4810m), Mont Rose (4634m) and Cervino (4478m), More than 50% of the territory has an elevation above 2000 metres asl. High mountain, glacial and periglacial environments cover a significant part of the territory. As the cryosphere is strongly sensitive to climate change, global warming effects are particularly evident in this alpine region, and they often affect environment and social and economic life, thus representing a key issue for politicians and people working and living in the valley. Among these effects, some of the most important are the decrease of water storage due to glaciers retreat and the increasing natural hazards as a consequence of rapid environmental dynamics. Hence the importance of monitoring glacial and periglacial environment, in order to quantify effects of climate change, to detect new dynamics and to manage consequences on the environment and the social life. In Aosta Valley the understanding of these phenomena is carried out by means of several actions, both at a regional scale and on specific representative sites. A multi-temporal analysis of aerial photographs, orthophotos and satellite imagery allows to detect glaciers evolution trend at a regional scale. All this information is collected in a Regional Glacier inventory, according to the World Glaciers Inventory standard and recommendations. Analysis of the information collected in the Inventory show that the total area presently covered by glaciers is about 135 km2; area changes occurred in the past has been about -44.3 km2, and -17 km2. between 1975 and 2005. Glacier inventory also gathers - for each of the about 200 glaciers - morphological data, information about events and photos both historical and present. Glacier mass balance (the difference resulting from the mass gained by the glacier through the

  7. Spatial and temporal variations of glacial erosion in the Rhône valley (Swiss Alps): Insights from numerical modeling

    OpenAIRE

    Sternai , Pietro; Herman , Frédéric; Valla , Pierre G.; Champagnac , Jean-Daniel

    2013-01-01

    Pietro Sternai : Now at: the Institut desSciences de laTerre d'Orléans - (ISTO), University of Orléans,France. Tel.: 33 631910242. E-mail addresses: , ; International audience; The present-day topography of the European Alps shows evidence of intense glacial reshaping. However, significant questions regarding Alpine landscape evolution during glaciations still persist. In this study, we focus on the Rhône valley (Swiss Alps), and use a ...

  8. Late Otiran sedimentation and glacial chronology in the Warwick valley, southeast Nelson

    International Nuclear Information System (INIS)

    Mabin, M.C.G.

    1983-01-01

    Approximately 14 m of sediment are exposed in a road cutting beneath a landslide deposit in the Warwick valley, southeast Nelson, New Zealand. Three radiocarbon dates and 5 pollen spectra were obtained from organic horizons in these sediments. The dates indicate that lacustrine sedimentation predominated from before 17 500 until 14 450 years ago. This was interrupted by a brief period of gravel aggradation between 17 500 and 16 650 years ago, which is attributed to a glacial advance. Vegetation at the site was consistently dominated by Cyperaceae, with some Gramineae, suggesting a bleak, treeless landscape. Correlation of this information with other radiocarbon dated sites indicates the need for some revision of the chronology of the late Otira Glaciation. A late phase of the Kumara 2 2 advance occurred between 17 000 and 16 000 years ago, and the Kumara 3 1 advance did not occur until after about 15 000 years ago. The end of the Otira Glaciation probably occurred between 13 000 and 12 500 years ago. (auth)

  9. Late Otiran sedimentation and glacial chronology in the Warwick valley, southeast Nelson

    Energy Technology Data Exchange (ETDEWEB)

    Mabin, M C.G. [Canterbury Univ., Christchurch (New Zealand). Dept. of Geology

    1983-01-01

    Approximately 14 m of sediment are exposed in a road cutting beneath a landslide deposit in the Warwick valley, southeast Nelson, New Zealand. Three radiocarbon dates and 5 pollen spectra were obtained from organic horizons in these sediments. The dates indicate that lacustrine sedimentation predominated from before 17,500 until 14,450 years ago. This was interrupted by a brief period of gravel aggradation between 17,500 and 16,650 years ago, which is attributed to a glacial advance. Vegetation at the site was consistently dominated by Cyperaceae, with some Gramineae, suggesting a bleak, treeless landscape. Correlation of this information with other radiocarbon dated sites indicates the need for some revision of the chronology of the late Otira Glaciation. A late phase of the Kumara 2/sub 2/ advance occurred between 17,000 and 16,000 years ago, and the Kumara 3/sub 1/ advance did not occur until after about 15,000 years ago. The end of the Otira Glaciation probably occurred between 13,000 and 12,500 years ago.

  10. Impact of valley fills on streamside salamanders in southern West Virginia

    Science.gov (United States)

    Wood, Petra Bohall; Williams, Jennifer M.

    2013-01-01

    Valley fills associated with mountaintop-removal mining bury stream headwaters and affect water quality and ecological function of reaches below fills. We quantified relative abundance of streamside salamanders in southern West Virginia during 2002 in three streams below valley fills (VFS) and in three reference streams (RS). We surveyed 36 10- × 2-m stream transects, once in summer and fall, paired by order and structure. Of 2,343 salamanders captured, 66.7% were from RS. Total salamanders (adults plus larvae) were more abundant in RS than VFS for first-order and second-order reaches. Adult salamanders had greater abundance in first-order reaches of RS than VFS. Larval salamanders were more abundant in second-order reaches of RS than VFS. No stream width or mesohabitat variables differed between VFS and RS. Only two cover variables differed. Silt cover, greater in VFS than RS first-order reaches, is a likely contributor to reduced abundance of salamanders in VFS. Second-order RS had more boulder cover than second-order VFS, which may have contributed to the higher total and larval salamander abundance in RS. Water chemistry assessments of our VFS and RS reported elevated levels of metal and ion concentrations in VFS, which can depress macroinvertebrate populations and likely affect salamander abundance. Valley fills appear to have significant negative effects on stream salamander abundance due to alterations in habitat structure, water quality and chemistry, and macroinvertebrate communities in streams below fills.

  11. Geohydrology of the Unconsolidated Valley-Fill Aquifer in the Meads Creek Valley, Schuyler and Steuben Counties, New York

    Science.gov (United States)

    Miller, Todd S.; Bugliosi, Edward F.; Reddy, James E.

    2008-01-01

    The Meads Creek valley encompasses 70 square miles of predominantly forested uplands in the upper Susquehanna River drainage basin. The valley, which was listed as a Priority Waterbody by the New York State Department of Environmental Conservation in 2004, is prone to periodic flooding, mostly in its downstream end, where development is occurring most rapidly. Hydraulic characteristics of the unconsolidated valley-fill aquifer were evaluated, and seepage rates in losing and gaining tributaries were calculated or estimated, in an effort to delineate the aquifer geometry and identify the factors that contribute to flooding. Results indicated that (1) Meads Creek gained about 61 cubic feet of flow per second (about 6.0 cubic feet per second per mile of stream channel) from ground-water discharge and inflow from tributaries in its 10.2-mile reach between the northernmost and southernmost measurement sites; (2) major tributaries in the northern part of the valley are not significant sources of recharge to the aquifer; and (3) major tributaries in the central and southern part of the valley provide recharge to the aquifer. The ground-water portion of streamflow in Meads Creek (excluding tributary inflow) was 11.3 cubic feet per second (ft3/s) in the central part of the valley and 17.2 ft3/s in the southern part - a total of 28.5 ft3/s. Ground-water levels were measured in 29 wells finished in unconfined deposits for construction of a potentiometric-surface map to depict directions of ground-water flow within the valley. In general, ground water flows from the edges of the valley toward Meads Creek and ultimately discharges to it. The horizontal hydraulic gradient for the entire 12-mile-long aquifer averages about 30 feet per mile, whereas the gradient in the southern fourth of the valley averages about half that - about 17 feet per mile. A water budget for the aquifer indicated that 28 percent of recharge was derived from precipitation that falls on the aquifer, 32

  12. Spin filling of valley-orbit states in a silicon quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Lim, W H; Yang, C H; Zwanenburg, F A; Dzurak, A S, E-mail: wee.lim@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW 2052 (Australia)

    2011-08-19

    We report the demonstration of a low-disorder silicon metal-oxide-semiconductor (Si MOS) quantum dot containing a tunable number of electrons from zero to N = 27. The observed evolution of addition energies with parallel magnetic field reveals the spin filling of electrons into valley-orbit states. We find a splitting of 0.10 meV between the ground and first excited states, consistent with theory and placing a lower bound on the valley splitting. Our results provide optimism for the realisation in the near future of spin qubits based on silicon quantum dots.

  13. Estimation of the recharge area contributing water to a pumped well in a glacial-drift, river-valley aquifer

    Science.gov (United States)

    Morrissey, Daniel J.

    1989-01-01

    The highly permeable, unconfined, glacial-drift aquifers that occupy most New England river valleys constitute the principal source of drinking water for many of the communities that obtain part or all of their public water supply from ground water. Recent events have shown that these aquifers are highly susceptible to contamination that results from a number of sources, such as seepage from wastewater lagoons, leaking petroleum-product storage tanks, and road salting. To protect the quality of water pumped from supply wells in these aquifers, it is necessary to ensure that potentially harmful contaminants do not enter the ground in the area that contributes water to the well. A high degree of protection can be achieved through the application of appropriate land-use controls within the contributing area. However, the contributing areas for most supply wells are not known. This report describes the factors that affect the size and shape of contributing areas to public supply wells and evaluates several methods that may be used to delineate contributing areas of wells in glacial-drift, river-valley aquifers. Analytical, two-dimensional numerical, and three-dimensional numerical models were used to delineate contributing areas. These methods of analysis were compared by applying them to a hypothetical aquifer having the dimensions and geometry of a typical glacial-drift, river-valley aquifer. In the model analyses, factors that control the size and shape of a contributing area were varied over ranges of values common to glacial-drift aquifers in New England. The controlling factors include the rate of well discharge, rate of recharge to the aquifer from precipitation and from adjacent till and bedrock uplands, distance of a pumping well from a stream or other potential source of induced recharge, degree of hydraulic connection of the aquifer with a stream, horizontal hydraulic conductivity of the aquifer, ratio of horizontal to vertical hydraulic conductivity, and

  14. Concentric Crater Fill in Utopia Planitia: Timing and Transitions Between Glacial and Periglacial Processes.

    Science.gov (United States)

    Levy, J.; Head, J.

    2008-09-01

    Concentric crater fill (CCF), lobate debris aprons (LDA), and lineated valley fill (LVF) have long been used as indicators of ground ice on Mars [1-3]. Formation models for these features range from aeolian modification [4], to rock-glacier processes [5], to debris-covered glacier processes [6-7], but are now largely constrained by the detection of material within lobate debris aprons that is 100s of meters thick, and which has dielectric properties consistent with water ice [8-9]. At ~30 cm/pixel HiRISE resolution, LVF, LDA, and CCF show complex surface textures, termed "brain coral terrain" [9], or, succinctly, "brain terrain" (BT) [10]. Polygonally patterned ground commonly is present in proximity to brain terrain, overlying it as "brain terrain-covering" polygons (BTC) [10]. Here we document spatial patterns of BT and BTC morphology present in four CCF-filled, ~10 km diameter craters in Utopia Planitia. We then evaluate formation processes for BT and BTC units. Brain Terrain (BT) Morphology At HiRISE resolution (~30 cm/pixel), concentric crater fill brain terrain displays a complex surface texture. Two distinct sub-textures are commonly present in brain terrain [9]: filled brain terrain (FBT) and hollow brain terrain (HBT) (Figure 1). Filled brain terrain (FBT) is composed of arcuate and cuspate mounds, commonly ~10-20 m wide and 10 - Hollow brain terrain (HBT) is composed of arcuate and cuspate features that are delimited by a convex-up boundary band, commonly ~4-6 m wide, surrounding a depression. HBT are of similar dimensions to FBT, but are seldom longer than ~100 m. HBT boundary bands are commonly parallel along the long axis, but may be tightly rounded or gradually tapered along the short axis. HBT features occur singly, or in linked groups. HBT features are commonly oriented in lineations which are concentric to the crater in which the unit is present. HBT lineation spacing is variable, but commonly has a wavelength of ~20 m. HBT is commonly present at

  15. Glacial evolution of the upper Gallego Valley (Panticosa mountains and Ribera de Biescas, Aragonese Pyrenees, Spain

    Directory of Open Access Journals (Sweden)

    Serrano-Cañadas, Enrique

    1991-12-01

    Full Text Available Glacial evolution in the upper Gallego Valley has been established by studying erosional and depositional land forms. Ten pulsations, related to five phases are described: Premaximal (F. G. 0, attributed to Middle Pleistocene; Peniglacier, with three expanding pulsations (F.G. 1, 2 y 3, is attributed to the Upper Pleistocene; Finipleniglacial with two phases of dynamic (F.G. 4 y 5' and climatic (F.G. 5 equilibrium associated with the Pleistocene deglaciation; high mountain phase (F.G. 6 y 7, with two morphogenetic episodes; and the Holocene pulses from the Little Ice Age.

    [es] Evolución glaciar del Alto Gallego (Montañas de Panticosa y Ribera de Biescas, Pirineo aragonés. Se reconstruye la evolución glaciar del Alto Gallego a partir del estudio de las formas de erosión y acumulación glaciar. Se describen diez pulsaciones, correspondientes a cinco fases mayores: Premáximo (F.G.O., atribuido al Pleistoceno medio; Pleniglaciar, con tres pulsaciones de expansión (F.G. 1,2 y 3, del Pleistoceno reciente; el Finipleniglaciar,con fases de equilibrio dinámico (F.G. 4y 5'y climático (F.G.S, ligadas a la deglaciación pleistocena; las fases de alta montaña, con dos pulsaciones (F.G. 6 y 7, atribuidas al Tardiglaciar; y las fases holocenas, de la Pequeña Edad del Hielo.
    [fr] Évolution glaciaire de Haut Gallego (montagnes de Panticosa et Rivage de Biescas, Pyrénées aragonaises. On étudie l'évolution glaciaire du Haut Gallego à partir de l'étude des formes d'érosion et accumulation glaciaire. On décrit dix pulsations, correspondant à cinq phases majeures: le Prémaximun (F.G. 0, attribué au Pléistocène moyen; le Pléniglaciaire avec trois pulsations d'expansion (F.G. 1, 2 et 3 attribuée au Pleistocene récent; le Pini-pléniglaciaire avec des phases d'équilibre dynamique (F.G. 4 et 5 et climatique (F.G. 5, liées à la déglaciation pléistocène; les phases de haute montagne, avec deux pulsations (F.G. 6 et 7 attribu

  16. Hydrogeologic Framework and Ground Water in Basin-Fill Deposits of the Diamond Valley Flow System, Central Nevada

    Science.gov (United States)

    Tumbusch, Mary L.; Plume, Russell W.

    2006-01-01

    The Diamond Valley flow system, an area of about 3,120 square miles in central Nevada, consists of five hydrographic areas: Monitor, Antelope, Kobeh, and Diamond Valleys and Stevens Basin. Although these five areas are in a remote part of Nevada, local government officials and citizens are concerned that the water resources of the flow system eventually could be further developed for irrigation or mining purposes or potentially for municipal use outside the study area. In order to better understand the flow system, the U.S. Geological Survey in cooperation with Eureka, Lander, and Nye Counties and the Nevada Division of Water Resources, is conducting a multi-phase study of the flow system. The principal aquifers of the Diamond Valley flow system are in basin-fill deposits that occupy structural basins comprised of carbonate rocks, siliciclastic sedimentary rocks, igneous intrusive rocks, and volcanic rocks. Carbonate rocks also function as aquifers, but their extent and interconnections with basin-fill aquifers are poorly understood. Ground-water flow in southern Monitor Valley is from the valley margins toward the valley axis and then northward to a large area of discharge by evapotranspiration (ET) that is formed south of a group of unnamed hills near the center of the valley. Ground-water flow from northern Monitor Valley, Antelope Valley, and northern and western parts of Kobeh Valley converges to an area of ground-water discharge by ET in central and eastern Kobeh Valley. Prior to irrigation development in the 1960s, ground-water flow in Diamond Valley was from valley margins toward the valley axis and then northward to a large discharge area at the north end of the valley. Stevens Basin is a small upland basin with internal drainage and is not connected with other parts of the flow system. After 40 years of irrigation pumping, a large area of ground-water decline has developed in southern Diamond Valley around the irrigated area. In this part of Diamond

  17. Pro-glacial soil variability and geomorphic activity - the case of three Swiss valleys

    NARCIS (Netherlands)

    Temme, A.J.A.M.; Lange, de K.

    2014-01-01

    Soils in pro-glacial areas are often approached from a chronosequence viewpoint. In the chronosequence approach, the objective is to derive rates of soil formation from differences in properties between soils of different age. For this reason, in chronosequence studies, soils are sampled in

  18. Coordinating plug-in electric vehicle charging with electric grid: Valley filling and target load following

    Science.gov (United States)

    Zhang, Li; Jabbari, Faryar; Brown, Tim; Samuelsen, Scott

    2014-12-01

    Plug-in electric vehicles (PEVs) shift energy consumption from petroleum to electricity for the personal transportation sector. This work proposes a decentralized charging protocol for PEVs with grid operators updating the cost signal. Each PEV calculates its own optimal charging profile only once based on the cost signal, after it is plugged in, and sends the result back to the grid operators. Grid operators only need to aggregate charging profiles and update the load and cost. The existing PEV characteristics, national household travel survey (NHTS), California Independent System Operator (CAISO) demand, and estimates for future renewable generation in California are used to simulate PEV operation, PEV charging profiles, grid demand, and grid net load (demand minus renewable). Results show the proposed protocol has good performance for overnight net load valley filling if the costs to be minimized are proportional to the net load. Annual results are shown in terms of overnight load variation and comparisons are made with grid level valley filling results. Further, a target load can be approached in the same manner by using the gap between current load and the target load as the cost. The communication effort involved is quite modest.

  19. Stratigraphic architecture of back-filled incised-valley systems: Pennsylvanian-Permian lower Cutler beds, Utah, USA

    Science.gov (United States)

    Wakefield, Oliver J. W.; Mountney, Nigel P.

    2013-12-01

    The Pennsylvanian to Permian lower Cutler beds collectively form the lowermost stratigraphic unit of the Cutler Group in the Paradox Basin, southeast Utah. The lower Cutler beds represent a tripartite succession comprising lithofacies assemblages of aeolian, fluvial and shallow-marine origin, in near equal proportion. The succession results from a series of transgressive-regressive cycles, driven by repeated episodes of climatic variation and linked changes in relative sea-level. Relative sea-level changes created a number of incised-valleys, each forming through fluvial incision during lowered base-level. Aeolian dominance during periods of relative sea-level lowstand aids incised-valley identification as the erosive bounding surface juxtaposes incised-valley infill against stacked aeolian faces. Relative sea-level rises resulted in back-flooding of the incised-valleys and their infill via shallow-marine and estuarine processes. Back-flooded valleys generated marine embayments within which additional local accommodation was exploited. Back-filling is characterised by a distinctive suite of lithofacies arranged into a lowermost, basal fill of fluvial channel and floodplain architectural elements, passing upwards into barform elements with indicators of tidal influence, including inclined heterolithic strata and reactivation surfaces. The incised-valley fills are capped by laterally extensive and continuous marine limestone elements that record the drowning of the valleys and, ultimately, flooding and accumulation across surrounding interfluves (transgressive surface). Limestone elements are characterised by an open-marine fauna and represent the preserved expression of maximum transgression.

  20. Water circulation within a high-Arctic glaciated valley (Petunia Bay, Central Spitsbergen): Recharge of a glacial river

    Science.gov (United States)

    Marciniak, Marek; Dragon, Krzysztof; Chudziak, Łukasz

    2014-05-01

    This article presents an investigation of the runoff of a glacial river located in the high Arctic region of Spitsbergen. The Ebba River runoff was measured during three melting seasons of 2007, 2008 and 2009. The most important component of the river recharge is the flow of melting water from glaciers (76-82% of total river runoff). However, the other components (surface water and groundwater) also made a significant contribution to the river recharge. The contribution of groundwater flow in total river runoff was estimated by measurements performed in four groups of piezometers located in different parts of the valley. The hydrogeological parameters that characterize shallow aquifer (thickness of the active layer, hydraulic conductivity, groundwater level fluctuations) were recognized by direct field measurements. The groundwater recharging river was the most variable recharge component, and ranged from 1% of the total runoff at the beginning of the melting season to even 27% at the end of summer.

  1. Geomorphology and natural hazards of the selected glacial valleys, Cordillera Blanca, Peru

    Czech Academy of Sciences Publication Activity Database

    Klimeš, Jan

    2012-01-01

    Roč. 47, č. 2 (2012), s. 25-31 ISSN 0300-5402 R&D Projects: GA ČR(CZ) GAP209/11/1000 Institutional research plan: CEZ:AV0Z30460519 Keywords : geomorphologic map * natural hazards * glacial lakes Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://web.natur.cuni.cz/ksgrrsek/acta/2012/Geographica_2_2012_Klimes.pdf

  2. Fluvial style change during the last glacial-interglacial transition in the middle Tisza valley (Hungary)

    NARCIS (Netherlands)

    Kasse, C.; Bohncke, S.J.P.; Vandenberghe, J.; Gabris, G.

    2010-01-01

    Sedimentary changes during the last ∼2500 years have been reconstructed from cored sedimentary records from the deltaic floodplain of the Lower Tagus Valley and the Tagus mudbelt on the continental shelf offshore Lisbon. We used a multi-proxy approach consisting of sedimentology, grainsize, pollen

  3. Post-glacial rock avalanches in the Obersee Valley, Glarner Alps, Switzerland

    Science.gov (United States)

    Nagelisen, Jan; Moore, Jeffrey R.; Vockenhuber, Christoph; Ivy-Ochs, Susan

    2015-06-01

    The geological record of prehistoric rock avalanches provides invaluable data for assessing the hazard posed by these rare but destructive mass movements. Here we investigate two large rock avalanches in the Obersee valley of the Glarner Alps, Switzerland, providing detailed mapping of landslide and related Quaternary phenomena, revised volume estimates for each event, and surface exposure dating of rock avalanche deposits. The Rautispitz rock avalanche originated from the southern flank of the Obersee valley, releasing approximately 91 million m3 of limestone on steeply-dipping bedding planes. Debris had maximum horizontal travel distance of ~ 5000 m, a fahrboeschung angle (relating fall height to length) of 18°, and was responsible for the creation of Lake Obersee; deposits are more than 130 m thick in places. The Platten rock avalanche encompassed a source volume of 11 million m3 sliding from the northern flank of the Obersee valley on similar steeply-dipping limestone beds (bedrock forms a syncline under the valley). Debris had a maximum horizontal travel distance of 1600 m with a fahrboeschung angle of 21°, and is more than 80 m thick in places. Deposits of the Platten rock avalanche are superposed atop those from the Rautispitz event at the end of the Obersee valley where they dam Lake Haslensee. Runout for both events was simulated using the dynamic analysis code DAN3D; results showed excellent match to mapped deposit extents and thickness and helped confirm the hypothesized single-event failure scenarios. 36Cl cosmogenic nuclide surface exposure dating of 13 deposited boulders revealed a Younger Dryas age of 12.6 ± 1.0 ka for the Rautispitz rock avalanche and a mid-Holocene age of 6.1 ± 0.8 ka for the Platten rock avalanche. A seismological trigger is proposed for the former event due to potentially correlated turbidite deposits in nearby Lake Zurich.

  4. Structural and functional characteristics of natural and constructed channels draining a reclaimed mountaintop removal and valley fill coal mine

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining has altered the landscape of the Central Appalachian region in the United States. The goals of this study were to 1) compare the structure and function of natural and constructed stream channels in forested and MTR/VF catch...

  5. Export of detritus and invertebrate from headwater streams: linking mountaintop removal and valley fill coal mining to downstream receiving waters

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining has resulted in large scale alteration of the topography, reduced forest productivity, and burial of headwater streams in the U.S. Central Appalachians. Although MTR/VF coal mining has occurred for several decades and the ...

  6. Erosion and filling of glacially-overdeepened troughs in the Northern Alpine Foreland as recorded in a deep drill core from Northern Switzerland

    Science.gov (United States)

    Dehnert, Andreas; Axel Kemna, Hans; Anselmetti, Flavio; Drescher-Schneider, Ruth; Graf, Hans Rudolf; Lowick, Sally; Preusser, Frank; Züger, Andreas; Furrer, Heinz

    2010-05-01

    As the major weather divide in Europe, the Alps represent one of the most interesting areas for understanding past climate change and its impact on continental environments. However, our knowledge of the Quaternary environmental history of the region is still rather limited, especially for the time preceding the last glaciation of the Alps. Geological and geophysical studies in the Wehntal, 20 km northwest of Zurich, Switzerland, in 2007 and 2008 have revealed the existence of a glacially overdeepened trough cut into Miocene molasse bedrock, which is today filled with ~90 to 180 m of Pleistocene sediments. In March 2009, a 93.6 m long sediment core (NW09/1) has been drilled east of the famous mammoth-site Niederweningen. This record is one of the very few sites in the northern Alpine Foreland that provides crucial insights into the timing of the erosion and infilling history of pre-Eemian glacially overdeepened troughs and also helps to understand the climate and environmental history. Based on chronological data deduced from the nearby, but shorter, 2007 core and on new multi-proxy data, the NW09/1 record is interpreted as: 4.1 m of in-situ molasse bedrock, overlain by 3.4 m of diamictic till. These glacial deposits were deposited by a Linth glacier lobe during Marine Isotope Stage (MIS) 6 (Rissian), although, the possibility that an even older glaciation was responsible cannot currently be excluded (e.g. MIS 8, luminescence dating, pollen interpretations, and palaeomagnetic studies in progress). It is suggested that this extensive ice advance, which once covered the entire Wehntal valley, caused the final erosion of the bedrock. The till is overlain by a 29.5 m thick sequence of laminated, carbonate-rich, fine-grained siliciclastic sediments that are interpreted as proglacial lake sediments. It is supposed that this unit was deposited in a proximal setting to a calving glacier-front confirmed by the presence of numerous dropstones. The damming of this Wehntal

  7. Valley-Fill Standstones in the Kootenai Formation on the Crow Indian Reservation, South-Central Montana

    Energy Technology Data Exchange (ETDEWEB)

    David A. Lopez

    1998-01-07

    Subsurface data is being collected, organized, and a digital database is being prepared. An ACCESS database and PC-Arcview if being used to manage and interpret the data. Well data and base map have been successfully imported to Arcview and customized. All of the four 30 feet by 60 feet geologic surface geologic quadrangles have been scanned to produce a digital surface data base for the Crow Reservation. Field investigations inventoried for the presence of valley-fill deposits. These appear to represent at least a four major westward-trending valley systems.

  8. Last glacial-Holocene temperatures and hydrology of the Sea of Galilee and Hula Valley from clumped isotopes in Melanopsis shells

    Science.gov (United States)

    Zaarur, Shikma; Affek, Hagit P.; Stein, Mordechai

    2016-04-01

    The carbonate clumped isotope (Δ47) thermometer was applied to fresh water snails (Melanopsis spp.) grown in the waters of the Sea of Galilee and Hula Valley, in the north of Israel. Modern shells, grown at known temperatures agree with the Δ47-T calibration of Zaarur et al. (2013). Fossil Melanopsis shells from 2 locations, Gesher Bnot Ya'aqov (at the southern tip of the Hula Valley) and the Sea of Galilee provide a temperature record for the region during the time interval of the past 20 kyrs. Glacial temperatures are ∼5 °C cooler than mid-Holocene and ∼3 °C cooler than modern, similar to other records in the region. These Δ47-derived temperatures are combined with δ18O of the shell carbonate to calculate the oxygen isotopic composition of the habitat waters. Contrary to global trends and other regional records, reconstructed δ18Owater values increase from the late glacial through the Holocene. This reversed signal reflects a decrease in the relative contribution of snowmelt to the watershed post-LGM and a transition to a more rain dominated inflow. A fairly constant difference in δ18Owater values between the Hula Valley and Sea of Galilee waters, suggests that the hydrological relationship of the two water bodies had remained constant, with the temperature changes playing only a minor role in the extent of evaporation of the Sea of Galilee relative to the Hula.

  9. Protection of drinking water reservoirs in buried glacial valleys in the ice-marginal landscape for securing future demand in the European perspective (ENCORE-Project).

    Science.gov (United States)

    Smit, F. W. H.; Bregman, E. P. H.

    2012-04-01

    Quaternary glaciations have left a significant sedimentological fingerprint in the subsurface of north Europe, in the form of buried glacial valleys. These structures are important drinking water reservoirs for millions of people in the ice-marginal landscape, but are increasingly threatened by anthropogenic pollution (nitrate, sulphate and organic pollutants) and geogenic pollution (salinization). That is one of the conclusion of a recent overview study in the IML of northern Europe from the North Sea to the southern Baltic area. Adequate policy making is yet not possible for several reasons: - Large amounts of data are needed to get a good grip on the lateral continuity of the complex infill. - The BurVal Working Group (2006) has shown that a combination of high resolution seismic survey, together with transient electromagnetic (TEM) surveys can provide realistic data for 3D hydrogeological models. However, these data have not yet been retrieved on a European scale. - Available borehole data can only be used as control points in 3D hydrological models, since the infill of buried glacial valleys is often lateral too complex to make sound interpolations possible. Pollution in buried glacial valleys crosses national borders in northern Europe and therefore national geological surveys have to cooperate in a newly formed European project on protection of these structures. The ENCORE - project (Environmental Conference of the European Regions) has shown in the past that it can facilitate fruitful European cooperation, which is urgently needed due to the costs of gathering data and due to knowledge gaps between different countries. By working together in a European context, these problems can be reduced so that better policy making is possible in order to secure our future drinking water availability.

  10. Natural heat storage in a brine-filled solar pond in the Tully Valley of central New York

    Science.gov (United States)

    Hayhurst, Brett; Kappel, William M.

    2014-01-01

    The Tully Valley, located in southern Onondaga County, New York, has a long history of unusual natural hydrogeologic phenomena including mudboils (Kappel, 2009), landslides (Tamulonis and others, 2009; Pair and others, 2000), landsurface subsidence (Hackett and others, 2009; Kappel, 2009), and a brine-filled sinkhole or “Solar pond” (fig. 1), which is documented in this report. A solar pond is a pool of salty water (brine) which stores the sun’s energy in the form of heat. The saltwater naturally forms distinct layers with increasing density between transitional zones (haloclines) of rapidly changing specific conductance with depth. In a typical solar pond, the top layer has a low salt content and is often times referred to as the upper convective zone (Lu and others, 2002). The bottom layer is a concentrated brine that is either convective or temperature stratified dependent on the surrounding environment. Solar insolation is absorbed and stored in the lower, denser brine while the overlying halocline acts as an insulating layer and prevents heat from moving upwards from the lower zone (Lu and others, 2002). In the case of the Tully Valley solar pond, water within the pond can be over 90 degrees Fahrenheit (°F) in late summer and early fall. The purpose of this report is to summarize observations at the Tully Valley brine-filled sinkhole and provide supplemental climate data which might affect the pond salinity gradients insolation (solar energy).

  11. Proglacial vs postglacial depostional environments, the opposing processes that filled the southern North Sea tunnel valleys

    DEFF Research Database (Denmark)

    Moreau, Julien; Huuse, Mads

    ­belt fashion. The formation of the 'backsets' would have been enhanced by supercooling due to the pressure drop during the upward flow of the water from the deepest part of the valleys towards the ice margin, freezing and thus capturing the sediments on the adverse slope. Recently this model has been...... river of Europe facing ice sheets and their proglacial depositional system generates a very intricate stratigraphy with multiple cross­cutting 'basins' in the form of valleys (c. 7 generations) which themselves contain up to 8 complete seismic sequences. Although the task to uild up a complete...

  12. VALLEY-FILL SANDSTONE IN THE KOOTENAI FORMATION ON THE CROW INDIAN RESERVATION, SOUTH-CENTRAL MONTANA

    Energy Technology Data Exchange (ETDEWEB)

    David A. Lopez

    1999-04-12

    The subsurface database has been completed for the project. An ACCESS database converted to PC-Arcview is being used to manage and interpret the data. Well data and base map data have been successfully imported into Arcview and customized to meet the needs of this project. Log tops and other data from all of the exploration wells in the area have been incorporated into the data base, except for some wells that have no available logs or other information. All of the four 30 x 60 feet geologic quadrangles have been scanned to produce a digital surface geologic data base for the Crow Reservation and all are nearing completion. Formal technical review prior to publication has been completed for all the quandrangles; Billings, Bridger; Hardin, and Lodge Grass. All four quadrangles are in the Bureau's Publications Department being prepared for submittal to a printer. Field investigations were completed during the third quarter, 1997. With the help of a student field assistant from the Crow Tribe, the entire project area was inventoried for the presence of valley-fill deposits in the Kootenai Formation. Field inventory has resulted in the identification of nine exposures of thick valley-fill deposits. These appear to represent at least four major westward-trending valley systems. All the channel localities have been measured and described in detail and paleocurrent data has been collected from all but one locality. In addition, two stratigraphic sections were measured in areas where channels are absent. One channel has been traced over a distance of about 60 miles and exhibits definite paleostructural control. An abstract describing this channel was submitted and the paper was presented at the Williston Basin Symposium in October, 1998. A follow on proposal to conduct a soil gas geochemical survey of the reservation was approved and the contract was received in late August. The sampling will be conducted next summer and will involve Crow students.

  13. Valley-Fill Sandstones in the Kootenai Formation on the Crow Indian Reservation, South-Central Montana

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, David A

    1998-07-03

    Subsurface data continues to be collected, organized, and a digital database is being prepared for the project. An ACCESS database and PC-Arcview is being used to manage and interpret the data. Well data and base map data have been successfully imported into Arcview and customized to meet the needs of this project. Log tops and other data from about ¾ of the exploration wells in the area have been incorporated into the data base. All of the four 30" X 60" geologic quadrangles have been scanned to produce a digital surface geologic data base for the Crow Reservation and all are nearing completion. Formal technical review prior to publication has been completed for all the quadrangles; Billings, Bridger; Hardin, and Lodge Grass. Final GIS edits are being made before being forwarded to the Bureau's Publications Department. Field investigations were completed during the third quarter, 1997. With the help of a student field assistant from the Crow Tribe, the entire project area was inventoried for the presence of valley-fill deposits in the Kootenai Formation. Field inventory has resulted in the identification of nine exposures of thick valley-fill deposits. These appear to represent at least four major westward-trending valley systems. All the channel localities have been measured and described in detail and paleocurrent data has been collected from all but one locality. In addition, two stratigraphic sections were measured in areas where channels are absent. One channel has bee traced over a distance of about 60 miles and exhibits definite paleostructural control. An abstract describing this channel has been submitted and accepted for presentation at the Williston Basin Symposium in October, 1998.

  14. Comparison of peak discharges among sites with and without valley fills for the July 8-9, 2001 flood in the headwaters of Clear Fork, Coal River basin, mountaintop coal-mining region, southern West Virginia

    Science.gov (United States)

    Wiley, Jeffrey B.; Brogan, Freddie D.

    2003-01-01

    The effects of mountaintop-removal mining practices on the peak discharges of streams were investigated in six small drainage basins within a 7-square-mile area in southern West Virginia. Two of the small basins had reclaimed valley fills, one basin had reclaimed and unreclaimed valley fills, and three basins did not have valley fills. Indirect measurements of peak discharge for the flood of July 8-9, 2001, were made at six sites on streams draining the small basins. The sites without valley fills had peak discharges with 10- to 25-year recurrence intervals, indicating that rainfall intensities and totals varied among the study basins. The flood-recurrence intervals for the three basins with valley fills were determined as though the peak discharges were those from rural streams without the influence of valley fills, and ranged from less than 2 years to more than 100 years.

  15. Enhancing rates of erosion and uplift through glacial perturbations

    Science.gov (United States)

    Norton, Kevin; Schlunegger, Fritz; Abbühl, Luca

    2010-05-01

    Research over the past decade has shown that the pattern of modern rock uplift in the Swiss Alps correlates with both long-term (thermochronometers) and short-term (cosmogenic nuclide-derived denudation rates, sediment loads, lake fills) measures of erosion. This correlation has been attributed alternately to isostatic causes (compensation to erosion and/or glacial unloading) and tectonic forces (ongoing collision and partial delamination). Of these potential driving forces, only isostatic compensation to erosion fits all available structural, geodetic, and flexural models. We explore this uplift-erosion relationship by analyzing river channel steepness for Alpine rivers. Zones of oversteepening, and hence enhanced stream power, are associated with glacial erosion and deposition during LGM and earlier glaciations, resulting in the focusing of erosion into the inner gorges which connect hanging tributary valleys to the main glacial trunk valley. These inner gorges are transient zones in which fluvial and hillslope processes are in the process of re-adjusting this glacially perturbed landscape. Bedrock properties also play a major role in the response time of these adjustments. Glacially generated knickzones are located within 5 km of the trunk stream in the Rhone valley where resistant lithologies dominate (gneiss), whereas the knickzones have migrated as much as 10 km or further in the less resistant rocks (buendnerschists) of the Rhine valley. We suggest that the rock uplift pattern is controlled by surface denudation as set by the glacial-interglacial history of the Alps. Rapid, focused erosion results in rapid rock uplift rates in the Central Swiss Alps, where glaciers were most active. An interesting ramification of this reasoning is that in the absence of glacial perturbation, both rock uplift rates and denudation rates would be substantially lower in this isostatically compensated mountain belt.

  16. Late glacial and Holocene history of the dry forest area in south Colombian Cauca Valley from sites Quilichao and la Teta

    International Nuclear Information System (INIS)

    Berrio, Juan Carlos; Hooghiemstra, Henry; Marchant, Rob; Rangel Orlando

    2002-01-01

    Two sedimentary cores with records of pollen and charcoal content within a chronology provided by radiocarbon are presented from the southern Cauca Valley in Colombia (1020 m). These records document the late glacial and Holocene dry forest vegetation, fire and environment history. Specifically, core Quilichao -1 (640 cm; 3 degrade 6' N, 76 degrade 31' W) represents the periods of 13/150-7720 14 C yr BP and following a hiatus from 2880 14 C yr BP to recent. Core la Teta - 2 (250 cm; 3 degrade 5' N, 76 degrade 32' W) provides a record from 8700 14 C yr BP around 13/150 21 4 C yr BP Quilichao shown an active late glacial drainage system and presence of dry forest. From 11/465-10/520 14 C yr BP dry forest consists mainly of Crotalaria Moraceae Urticaceae, Melastomataceae, Piper and low stature trees, such as Acalypha, Alchornea, Cecropia and Celtis. At higher elevation on the slopes Andean forest with Quercus, Hedyosmum, Myrica and Alnus are common

  17. Hydrogeology of the Susquehanna River valley-fill aquifer system in the Endicott-Vestal area of southwestern Broome County, New York

    Science.gov (United States)

    Randall, Allan D.; Kappel, William M.

    2015-07-29

    The village of Endicott, New York, and the adjacent town of Vestal have historically used groundwater from the Susquehanna River valley-fill aquifer system for municipal water supply, but parts of some aquifers in this urban area suffer from legacy contamination from varied sources. Endicott would like to identify sites distant from known contamination where productive aquifers could supply municipal wells with water that would not require intensive treatment. The distribution or geometry of aquifers within the Susquehanna River valley fill in western Endicott and northwestern Vestal are delineated in this report largely on the basis of abundant borehole data that have been compiled in a table of well records.

  18. Preliminary evaluation of the radioactive waste isolation potential of the alluvium-filled valleys of the Great Basin

    International Nuclear Information System (INIS)

    Smyth, J.R.; Crowe, B.M.; Halleck, P.M.; Reed, A.W.

    1979-08-01

    The occurrences, geologic features, hydrology, and thermal, mechanical, and mineralogical properties of the alluvium-filled valleys are compared with those of other media within the Great Basin. Computer modeling of heat conduction indicates that heat generated by the radioactive waste can be dissipated through the alluvium in a manner that will not threaten the integrity of the repository, although waste emplacement densities will be lower than for other media available. This investigation has not revealed any failure mechanism by which one can rule out alluvium as a primary waste isolation medium. However, the alluvium appears to rank behind one or more other possible media in all properties examined except, perhaps, in sorption properties. It is therefore recommended that alluvium be considered as a secondary isolation medium unless primary sites in other rock types in the Great Basin are eliminated from consideration on grounds other than those considered here

  19. The Holocene sedimentary history of the Kangerlussuaq Fjord-valley fill, West Greenland

    DEFF Research Database (Denmark)

    Storms, Joep E.A.; de Winter, Ilja L.; Overeem, Irina

    2012-01-01

    valleys. Based on published and new land- and sea-based geophysical data, radiocarbon dates and geological observations we have characterized the infill and reconstructed the sedimentation history during the Holocene. Based on a revised sea level curve and data presented in this paper we defined three...... depocenters by a flood plain which transferred sediment from the GIS to the Keglen delta. Ongoing sea level fall due to glacio-isostastic uplift combined with a gradually cooler and dryer climate resulted in terrace formation along the Watson River flood plain. Around 4000 yr BP, the GIS margin reached its...... most landward location and began to advance to its present location. The final phase (Phase III; channels...

  20. Transgressive systems tract development and incised-valley fills within a quaternary estuary-shelf system: Virginia inner shelf, USA

    Science.gov (United States)

    Foyle, A.M.; Oertel, G.F.

    1997-01-01

    High-frequency Quaternary glacioeustasy resulted in the incision of six moderate- to high-relief fluvial erosion surfaces beneath the Virginia inner shelf and coastal zone along the updip edges of the Atlantic continental margin. Fluvial valleys up to 5 km wide, with up to 37 m of relief and thalweg depths of up to 72 m below modern mean sea level, cut through underlying Pleistocene and Mio-Pliocene strata in response to drops in baselevel on the order of 100 m. Fluvially incised valleys were significantly modified during subsequent marine transgressions as fluvial drainage basins evolved into estuarine embayments (ancestral generations of the Chesapeake Bay). Complex incised-valley fill successions are bounded by, or contain, up to four stacked erosional surfaces (basal fluvial erosion surface, bay ravinement, tidal ravinement, and ebb-flood channel-base diastem) in vertical succession. These surfaces, combined with the transgressive oceanic ravinement that generally caps incised-valley fills, control the lateral and vertical development of intervening seismic facies (depositional systems). Transgressive stratigraphy characterizes the Quaternary section beneath the Virginia inner shelf where six depositional sequences (Sequences I-VI) are identified. Depositional sequences consist primarily of estuarine depositional systems (subjacent to the transgressive oceanic ravinement) and shoreface-shelf depositional systems; highstand systems tract coastal systems are thinly developed. The Quaternary section can be broadly subdivided into two parts. The upper part contains sequences consisting predominantly of inner shelf facies, whereas sequences in the lower part of the section consist predominantly of estuarine facies. Three styles of sequence preservation are identified. Style 1, represented by Sequences VI and V, is characterized by large estuarine systems (ancestral generations of the Chesapeake Bay) that are up to 40 m thick, have hemicylindrical wedge geometries

  1. The development and genesis of a small thaw lake filling the Skaliska Basin during the Late Glacial and Holocene

    Directory of Open Access Journals (Sweden)

    Stachowicz-Rybka Renata

    2013-06-01

    Full Text Available The northern part of the Mazury Lake District is marked by the presence of a depression described as the Skaliska Basin. At the end of the Pleistocene, the Skaliska Basin was the site of functioning of a thaw lake, within series of laminated clayey sediments were formed. The surface of the clayey sediments was overlain by a sandy fan. Blocks of dead ice underlying the fan and the overlying surface of the clayey sediments were the origin of small isolated water basins. Since the Allerod they were filled with limnic sediments, passing into peats towards the upper part. In order to reconstruct the vegetational history of the Skaliska Basin and the conditions of sedimentation of the lacustrine gyttjas and peats, several sections were obtained from such basins and subjected to examination of plant macroremains, palaeolimnological analysis and AMS dating. Sedimentation of lacustrine sediments began with sands with an admixture of silt and peat. The beginning of sedimentation of lacustrine sands of aeolian origin falls within the Allerod, whereas the end of that process in ca the middle of the Preboreal. Sands are frequently overlain by a strongly decomposed lacustrine dy sediment. Subsequently a sequence of detritus gyttja accumulated. The complex of gyttjas is interbedded with occasional Scirpo-Typheti peats. Sedimentation of lacustrine sediments is followed by accumulation of peats formed within communities with tall sedges. These communities, according to their compoition, correspond to the associations of Cicuto- Caricetum pseudocyperi Boer. et Siss. and Caricetum elatae Koch. The upper part comprises peats resembling the present-day community of Sphagnum centrale, displaying features of a transition bog. Also the occurrence of Eriophorum vaginatum confirms changes towards ombrotrophic conditions. The uppermost part of the sections often comprises heavily decomposed peat with components no longer identifiable by macroscopic analysis.

  2. Geohydrology and Water Quality of the Valley-Fill Aquifer System in the Upper Sixmile Creek and West Branch Owego Creek Valleys in the Town of Caroline, Tompkins County, New York

    Science.gov (United States)

    Miller, Todd S.

    2009-01-01

    In 2002, the U.S. Geological Survey, in cooperation with the Town of Caroline and Tompkins County Planning Department, began a study of the valley-fill aquifer system in upper Sixmile Creek and headwaters of West Branch Owego Creek valleys in the Town of Caroline, NY. The purpose of the study is to provide geohydrologic data to county and town planners as they develop a strategy to manage and protect their water resources. The first aquifer reach investigated in this series is in the Town of Caroline and includes the upper Sixmile Creek valley and part of West Branch Owego Creek valley. The portions of the valley-fill aquifer system that are comprised of saturated coarse-grained sediments including medium to coarse sand and sandy gravel form the major aquifers. Confined sand and gravel units form the major aquifers in the western and central portions of the upper Sixmile Creek valley, and an unconfined sand and gravel unit forms the major aquifer in the eastern portion of the upper Sixmile Creek valley and in the headwaters of the West Branch Owego Creek valley. The valley-fill deposits are thinnest near the edges of the valley where they pinch out along the till-mantled bedrock valley walls. The thickness of the valley fill in the deepest part of the valley, at the western end of the study area, is about 100 feet (ft); the thickness is greater than 165 ft on top of the Valley Heads Moraine in the central part of the valley. An estimated 750 people live over and rely on groundwater from the valley-fill aquifers in upper Sixmile Creek and West Branch Owego Creek valleys. Most groundwater withdrawn from the valley-fill aquifers is pumped from wells with open-ended 6-inch diameter casings; the remaining withdrawals are from shallow dug wells or cisterns that collect groundwater that discharges to springs (especially in the Brooktondale area). The valley-fill aquifers are the sources of water for about 200 households, several apartment complexes, two mobile home parks

  3. Paleo erosion rates and climate shifts recorded by Quaternary cut-and-fill sequences in the Pisco valley, central Peru

    Science.gov (United States)

    Bekaddour, Toufik; Schlunegger, Fritz; Vogel, Hendrik; Delunel, Romain; Norton, Kevin P.; Akçar, Naki; Kubik, Peter

    2014-03-01

    Fluvial cut-and-fill sequences have frequently been reported from various sites on Earth. Nevertheless, the information about the past erosional regime and hydrological conditions have not yet been adequately deciphered from these archives. The Quaternary terrace sequences in the Pisco valley, located at ca. 13°S, offer a manifestation of an orbitally-driven cyclicity in terrace construction where phases of sediment accumulation have been related to the Minchin (48-36 ka) and Tauca (26-15 ka) lake level highstands on the Altiplano. Here, we present a 10Be-based sediment budget for the cut-and-fill terrace sequences in this valley to quantify the orbitally forced changes in precipitation and erosion. We find that the Minchin period was characterized by an erosional pulse along the Pacific coast where denudation rates reached values as high as 600±80 mm/ka for a relatively short time span lasting a few thousands of years. This contrasts to the younger pluvial periods and the modern situation when 10Be-based sediment budgets register nearly zero erosion at the Pacific coast. We relate these contrasts to different erosional conditions between the modern and the Minchin time. First, the sediment budget infers a precipitation pattern that matches with the modern climate ca. 1000 km farther north, where highly erratic and extreme El Niño-related precipitation results in fast erosion and flooding along the coast. Second, the formation of a thick terrace sequence requires sufficient material on catchment hillslopes to be stripped off by erosion. This was most likely the case immediately before the start of the Minchin period, because this erosional epoch was preceded by a >50 ka-long time span with poorly erosive climate conditions, allowing for sufficient regolith to build up on the hillslopes. Finally, this study suggests a strong control of orbitally and ice sheet forced latitudinal shifts of the ITCZ on the erosional gradients and sediment production on the western

  4. Subglacial tunnel valleys in the Alpine foreland: an example from Bern, Switzerland

    International Nuclear Information System (INIS)

    Duerst Stucki, M.; Reber, R.; Schlunegger, F.

    2010-01-01

    The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4'000 borehole data within a 430 km 2 -large area reveal the presence of a network of >200 m-deep and 1'000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20 o steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50-100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure. (authors)

  5. Facies Analysis of Tertiary Basin-Filling Rocks of the Death Valley Regional Ground-Water System and Surrounding Areas, Nevada and California; TOPICAL

    International Nuclear Information System (INIS)

    Sweetkind, D.S.; Fridrich, C.J.; Taylor, Emily

    2002-01-01

    Existing hydrologic models of the Death Valley region typically have defined the Cenozoic basins as those areas that are covered by recent surficial deposits, and have treated the basin-fill deposits that are concealed under alluvium as a single unit with uniform hydrologic properties throughout the region, and with depth. Although this latter generalization was known to be flawed, it evidently was made because available geologic syntheses did not provide the basis for a more detailed characterization. As an initial attempt to address this problem, this report presents a compilation and synthesis of existing and new surface and subsurface data on the lithologic variations between and within the Cenozoic basin fills of this region. The most permeable lithologies in the Cenozoic basin fills are freshwater limestones, unaltered densely welded tuffs, and little-consolidated coarse alluvium. The least permeable lithologies are playa claystones, altered nonwelded tuffs, and tuffaceous and cl ay-matrix sediments of several types. In all but the youngest of the basin fills, permeability probably decreases strongly with depth owing to a typically increasing abundance of volcanic ash or clay in the matrices of the clastic sediments with increasing age (and therefore with increasing depth in general), and to increasing consolidation and alteration (both hydrothermal and diagenetic) with increasing depth and age. This report concludes with a categorization of the Cenozoic basins of the Death Valley region according to the predominant lithologies in the different basin fills and presents qualitative constraints on the hydrologic properties of these major lithologic categories

  6. A Study of the Connection Among Basin-Fill Aquifers, Carbonate-Rock Aquifers, and Surface-Water Resources in Southern Snake Valley, Nevada

    Science.gov (United States)

    ,

    2008-01-01

    The Secretary of the Interior through the Southern Nevada Public Lands Management Act approved funding for research to improve understanding of hydrologic systems that sustain numerous water-dependent ecosystems on Federal lands in Snake Valley, Nevada. Some of the streams and spring-discharge areas in and adjacent to Great Basin National Park have been identified as susceptible to ground-water withdrawals (Elliott and others, 2006) and research has shown a high potential for ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide known as the Limestone Hills (Welch and others, 2007). Comprehensive geologic, hydrologic, and chemical information will be collected and analyzed to assess the hydraulic connection between basin-fill aquifers and surface-water resources, water-dependent ecological features, and the regional carbonate-rock aquifer, the known source of many high-discharge springs. Understanding these connections is important because proposed projects to pump and export ground water from Spring and Snake Valleys in Nevada may result in unintended capture of water currently supplying springs, streams, wetlands, limestone caves, and other biologically sensitive areas (fig. 1). The methods that will be used in this study may be transferable to other areas in the Great Basin. The National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service, and U.S. Forest Service submitted the proposal for funding this research to facilitate science-based land management. Scientists from the U.S. Geological Survey (USGS) Water Resources and Geologic Disciplines, and the University of Nevada, Reno, will accomplish four research elements through comprehensive data collection and analysis that are concentrated in two distinct areas on the eastern and southern flanks of the Snake Range (fig. 2). The projected time line for this research is from July 2008 through September 2011.

  7. Subglacial tunnel valleys in the Alpine foreland: an example from Bern, Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Duerst Stucki, M.; Reber, R.; Schlunegger, F.

    2010-12-15

    The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4'000 borehole data within a 430 km{sup 2}-large area reveal the presence of a network of >200 m-deep and 1'000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20 {sup o} steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50-100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure. (authors)

  8. Glacial cycles

    DEFF Research Database (Denmark)

    Kaufmann, R. K.; Juselius, Katarina

    We use a statistical model, the cointegrated vector autoregressive model, to assess the degree to which variations in Earth's orbit and endogenous climate dynamics can be used to simulate glacial cycles during the late Quaternary (390 kyr-present). To do so, we estimate models of varying complexity...... and compare the accuracy of their in-sample simulations. Results indicate that strong statistical associations between endogenous climate variables are not enough for statistical models to reproduce glacial cycles. Rather, changes in solar insolation associated with changes in Earth's orbit are needed...... to simulate glacial cycles accurately. Also, results suggest that non-linear 10 dynamics, threshold effects, and/or free oscillations may not play an overriding role in glacial cycles....

  9. Sink detection on tilted terrain for automated identification of glacial cirques

    Science.gov (United States)

    Prasicek, Günther; Robl, Jörg; Lang, Andreas

    2016-04-01

    Glacial cirques are morphologically distinct but complex landforms and represent a vital part of high mountain topography. Their distribution, elevation and relief are expected to hold information on (1) the extent of glacial occupation, (2) the mechanism of glacial cirque erosion, and (3) how glacial in concert with periglacial processes can limit peak altitude and mountain range height. While easily detectably for the expert's eye both in nature and on various representations of topography, their complicated nature makes them a nemesis for computer algorithms. Consequently, manual mapping of glacial cirques is commonplace in many mountain landscapes worldwide, but consistent datasets of cirque distribution and objectively mapped cirques and their morphometrical attributes are lacking. Among the biggest problems for algorithm development are the complexity in shape and the great variability of cirque size. For example, glacial cirques can be rather circular or longitudinal in extent, exist as individual and composite landforms, show prominent topographic depressions or can entirely be filled with water or sediment. For these reasons, attributes like circularity, size, drainage area and topology of landform elements (e.g. a flat floor surrounded by steep walls) have only a limited potential for automated cirque detection. Here we present a novel, geomorphometric method for automated identification of glacial cirques on digital elevation models that exploits their genetic bowl-like shape. First, we differentiate between glacial and fluvial terrain employing an algorithm based on a moving window approach and multi-scale curvature, which is also capable of fitting the analysis window to valley width. We then fit a plane to the valley stretch clipped by the analysis window and rotate the terrain around the center cell until the plane is level. Doing so, we produce sinks of considerable size if the clipped terrain represents a cirque, while no or only very small sinks

  10. The rheological behavior of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Ledevin, M.; Arndt, N.; Simionovici, A.

    2014-05-01

    A 100 m-thick complex of near-vertical carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma) in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the dikes (ca. 1 m on average) and by the abundance of completely shattered rocks. The dike-and-sill organization of the fracture network and the upward narrowing of some of the large veins indicate that at least part of the fluid originated at depth and migrated upward in this hydrothermal plumbing system. Abundant angular fragments of silicified country rock are suspended and uniformly distributed within the larger dikes. Jigsaw-fit structures and confined bursting textures indicate that hydraulic fracturing was at the origin of the veins. The confinement of the dike system beneath an impact spherule bed suggests that the hydrothermal circulations were triggered by the impact and located at the external margin of a large crater. From the geometry of the dikes and the petrography of the cherts, we infer that the fluid that invaded the fractures was thixotropic. On one hand, the injection of black chert into extremely fine fractures is evidence for low viscosity at the time of injection; on the other hand, the lack of closure of larger veins and the suspension of large fragments in a chert matrix provide evidence of high viscosity soon thereafter. The inference is that the viscosity of the injected fluid increased from low to high as the fluid velocity decreased. Such rheological behavior is characteristic of media composed of solid and colloidal particles suspended in a liquid. The presence of abundant clay-sized, rounded particles of silica, carbonaceous matter and clay minerals, the high proportion of siliceous matrix and the capacity of colloidal silica to form cohesive 3-D networks through gelation, account for the viscosity increase and thixotropic behavior of the fluid that filled the veins. Stirring and

  11. Probability of Elevated Volatile Organic Compound (VOC) Concentrations in Groundwater in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

    Science.gov (United States)

    Rupert, Michael G.; Plummer, Niel

    2009-01-01

    This raster data set delineates the predicted probability of elevated volatile organic compound (VOC) concentrations in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps was developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

  12. Probability of Elevated Nitrate Concentrations in Groundwater in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

    Science.gov (United States)

    Rupert, Michael G.; Plummer, Niel

    2009-01-01

    This raster data set delineates the predicted probability of elevated nitrate concentrations in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps was developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

  13. New glacial evidences at the Talacasto paleofjord (Paganzo basin, W-Argentina) and its implications for the paleogeography of the Gondwana margin

    Science.gov (United States)

    Aquino, Carolina Danielski; Milana, Juan Pablo; Faccini, Ubiratan Ferrucio

    2014-12-01

    The Talacasto paleovalley is situated in the Central Precordillera of San Juan, Argentina, where upper Carboniferous-Permian rocks (Paganzo Group) rest on Devonian sandstones of the Punta Negra Formation. This outcrop is an excellent example of a glacial valley-fill sequence that records at least two high-frequency cycles of the advance and retreat of a glacier into the valley. The paleocurrent analysis shows transport predominantly to the south, indicating that at this site the ice flow differs from the other nearby paleovalleys. Evidence of the glacial origin of this valley can be seen in the glacial striae on the valley's sides, as well as the U-shape of the valley, indicated by very steep locally overhanging valley walls. Deglaciation is indicated by a set of retransported conglomerates deposited in a shallow-water environment followed by a transgressive succession, which suggests eustatic rise due to meltwater input to the paleofjord. The complete sedimentary succession records distinct stages in the evolution of the valley-fill, represented by seven stratigraphical units. These units are identified based on facies associations and their interpreted depositional setting. Units 1 to 5 show one cycle of deglaciation and unit 6 marks the beginning of a new cycle of glacier advance which is characterized by different types of glacial deposits. All units show evidence of glacial influence such as dropstones and striated clasts, which indicates that the glaciers were always present in the valley or in adjacent areas during sedimentation. The Talacasto paleofjord provides good evidence of the Late Paleozoic Gondwana glaciation in western Argentina and examples of sedimentary successions which have been interpreted as being deposited by a confined wet-based glacier in advance and retreat cycles, with eventual release of icebergs into the basin. The outcrop is also a key for reconstructing the local glacial paleogeography, and it suggests a new interpretation that is

  14. Quaternary glaciation of the Tashkurgan Valley, Southeast Pamir

    Science.gov (United States)

    Owen, Lewis A.; Chen, Jie; Hedrick, Kathyrn A.; Caffee, Marc W.; Robinson, Alexander C.; Schoenbohm, Lindsay M.; Yuan, Zhaode; Li, Wenqiao; Imrecke, Daniel B.; Liu, Jinfeng

    2012-07-01

    The Quaternary glacial history of Tashkurgan valley, in the transition between the Pamir and Karakoram, in Xinjiang Province, China was examined using remote sensing, field mapping, geomorphic analysis of landforms and sediments, and 10Be terrestrial cosmogenic nuclide dating. Moraines were assigned to four glacial stages: 1) the Dabudaer glacial stage that dates to the penultimate glacial cycle and/or earlier, and may represent one or more glaciations; 2) the Tashkurgan glacial stage that dates to early last glacial, most likely Marine Oxygen Isotope Stage (MIS) 4; 3) the Hangdi glacial stage that dates to MIS 2, possibly early MIS 2; and 4) the Kuzigun glacial stage that dates to the MIS 2, possibly the global Last Glacial Maximum, and is younger than the Hangdi glacial stage. Younger moraines and rock glaciers are present at the heads of tributary valleys; but these were inaccessible because they are located close to politically sensitive borders with Pakistan, Afghanistan and Tajikistan. Glaciers during the Dabudaer glacial stage advanced into the central part of the Tashkurgan valley. During the Tashkurgan glacial stages, glaciers advanced several kilometers beyond the mouths of the tributary valleys into the Tashkurgan valley. Glaciers during the Hangdi and Kuzigun glacial stages advanced just beyond the mouths of the tributary valleys. Glaciation in this part of the Himalayan-Tibetan orogen is likely strongly controlled by northern hemisphere climate oscillations, although a monsoonal influence on glaciation cannot be ruled out entirely.

  15. Reconstruction of a glacial lake outburst flood (GLOF) in the Engaño Valley, Chilean Patagonia: Lessons for GLOF risk management.

    Science.gov (United States)

    Anacona, Pablo Iribarren; Mackintosh, Andrew; Norton, Kevin

    2015-09-15

    Floods from moraine-dammed lake failures can have long standing effects not only on riverine landscapes but also on mountain communities due to the high intensity (i.e. great depth and high velocities) and damaging capacity of glacial lake outburst floods (GLOFs). GLOFs may increase in frequency as glaciers retreat and new lakes develop and there is an urgent need to better understand GLOF dynamics and the measures required to reduce their negative outcomes. In Patagonia at least 16 moraine-dammed lakes have failed in historic time, however, data about GLOF dynamics and impacts in this region are limited. We reconstruct a GLOF that affected a small village in Chilean Patagonia in March 1977, by semi structured interviews, interpretation of satellite images and 2D hydraulic modelling. This provides insight into the GLOF dynamics and the planning issues that led to socioeconomic consequences, which included village relocation. Modelling shows that the water released by the GLOF was in the order of 12-13 × 10(6)m(3) and the flood lasted for about 10h, reaching a maximum depth of ~1.5m in Bahía Murta Viejo, ~ 26 km from the failed lake. The lake had characteristics in common with failed lakes worldwide (e.g. the lake was in contact with a retreating glacier and was dammed by a narrow-steep moraine). The absence of land-use planning and the unawareness of the GLOF hazard contributed to the village flooding. The Río Engaño GLOF illustrates how small-scale and short-distance migration is a reasonable coping strategy in response to a natural hazard that may increase in frequency as atmospheric temperature rises and glaciers retreat. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Reconstructing temperatures in the Maritime Alps, Italy, since the Last Glacial Maximum using cosmogenic noble gas paleothermometry

    Science.gov (United States)

    Tremblay, Marissa; Spagnolo, Matteo; Ribolini, Adriano; Shuster, David

    2016-04-01

    The Gesso Valley, located in the southwestern-most, Maritime portion of the European Alps, contains an exceptionally well-preserved record of glacial advances during the late Pleistocene and Holocene. Detailed geomorphic mapping, geochronology of glacial deposits, and glacier reconstructions indicate that glaciers in this Mediterranean region responded to millennial scale climate variability differently than glaciers in the interior of the European Alps. This suggests that the Mediterranean Sea somehow modulated the climate of this region. However, since glaciers respond to changes in temperature and precipitation, both variables were potentially influenced by proximity to the Sea. To disentangle the competing effects of temperature and precipitation changes on glacier size, we are constraining past temperature variations in the Gesso Valley since the Last Glacial Maximum (LGM) using cosmogenic noble gas paleothermometry. The cosmogenic noble gases 3He and 21Ne experience diffusive loss from common minerals like quartz and feldspars at Earth surface temperatures. Cosmogenic noble gas paleothermometry utilizes this open-system behavior to quantitatively constrain thermal histories of rocks during exposure to cosmic ray particles at the Earth's surface. We will present measurements of cosmogenic 3He in quartz sampled from moraines in the Gesso Valley with LGM, Bühl stadial, and Younger Dryas ages. With these 3He measurements and experimental data quantifying the diffusion kinetics of 3He in quartz, we will provide a preliminary temperature reconstruction for the Gesso Valley since the LGM. Future work on samples from younger moraines in the valley system will be used to fill in details of the more recent temperature history.

  17. Selenium in ecosystems within the mountaintop coal mining and valley-fill region of southern West Virginia-assessment and ecosystem-scale modeling

    Science.gov (United States)

    Presser, Theresa S.

    2013-01-01

    Coal and associated waste rock are among environmental selenium (Se) sources that have the potential to affect reproduction in fish and aquatic birds. Ecosystems of southern West Virginia that are affected by drainage from mountaintop coal mines and valleys filled with waste rock in the Coal, Gauley, and Lower Guyandotte watersheds were assessed during 2010 and 2011. Sampling data from earlier studies in these watersheds (for example, Upper Mud River Reservoir) and other mining-affected watersheds also are included to assess additional hydrologic settings and food webs for comparison. Basin schematics give a comprehensive view of sampled species and Se concentration data specific to location and date. Food-web diagrams document the progression of Se trophic transfer across suspended particulate material, invertebrates, and fish for each site to serve as the basis for developing an ecosystem-scale model to predict Se exposure within the hydrologic conditions and food webs of southern West Virginia. This approach integrates a site-specific predator’s dietary exposure pathway into modeling to ensure an adequate link to Se toxicity and, thus, to species vulnerability. Site-specific fish abundance and richness data in streams documented various species of chub, shiner, dace, darters, bass, minnow, sunfish, sucker, catfish, and central stoneroller (Campostoma anomalum), mottled sculpin (Cottus bairdii), and least brook lamprey (Lampetra aepyptera). However, Se assessment species for streams, and hence, model species for streams, were limited to creek chub (Semotilus atromaculatus) and central stoneroller. Both of these species of fish are generally considered to have a high tolerance for environmental stress based on traditional comparative fish community assessment, with creek chub being present at all sites. Aquatic insects (mayfly, caddisfly, stonefly, dobsonfly, chironomid) were the main invertebrates sampled in streams. Collection of suspended particulate material

  18. Glacial loess or shoreface sands: a re-interpretation of the Upper Ordovician (Ashgillian) glacial Ammar Formation, Southern Jordan

    Science.gov (United States)

    Turner, B. R.; Makhlouf, I. M.; Armstrong, H. A.

    2003-04-01

    Upper Ordovician (Ashgillian) glacial deposits of the Ammar Formation, Southern Jordan, comprise locally deformed, structureless fine sandstone, incised by glacial channels filled by braided outwash plain sandstones and transgressive marine mudstones. The structureless sandstones, previously interpreted as a glacial rock flour or loessite derived from the underlying undisturbed sandstones, differ significantly from typical loessite and contain hitherto unrecognised sedimentary structures, including hummocky cross-stratification. The sandstones, which grade laterally and vertically into stratigraphically equivalent undeformed marginal marine sandstones, are interpreted as a deformed facies of the underlying sandstones, deposited in a similar high energy shoreface environment. Although deformation of the shoreface sandstones was post-depositional, the origin of the deformation, and its confinement to the Jebel Ammar area is unknown. Deformation due to the weight of the overlying ice is unlikely as the glaciofluvial channels are now thought to have been cut by tunnel valley activity not ice. A more likely mechanism is post-glacial crustal tectonics. Melting of ice caps is commonly associated with intraplate seismicity and the development of an extensional crustal stress regime around the perimeter of ice caps; the interior is largely aseismic because the weight of the ice supresses seismic activity and faulting. Since southern Jordan lay close to the ice cap in Saudi Arabia it may have been subjected to postglacial seismicity and crustal stress, which induced ground shaking, reduced overburden pressure, increased hydrostatic pressure and possibly reactivation of existing tectonic faults. This resulted in liquefaction and extensive deformation of the sediments, which show many characteristics of seismites, generated by earthquake shocks. Since the glaciation was a very short-lived event (0.2-1 Ma), deglaciation and associated tectonism triggering deformation, lasted

  19. Late Ordovician (Ashgillian) glacial deposits in southern Jordan

    Science.gov (United States)

    Turner, Brian R.; Makhlouf, Issa M.; Armstrong, Howard A.

    2005-11-01

    The Late Ordovician (Ashgillian) glacial deposits in southern Jordan, comprise a lower and upper glacially incised palaeovalley system, occupying reactivated basement and Pan-African fault-controlled depressions. The lower palaeovalley, incised into shoreface sandstones of the pre-glacial Tubeiliyat Formation, is filled with thin glaciofluvial sandstones at the base, overlain by up to 50 m of shoreface sandstone. A prominent glaciated surface near the top of this palaeovalley-fill contains intersecting glacial striations aligned E-W and NW-SE. The upper palaeovalley-fill comprises glaciofluvial and marine sandstones, incised into the lower palaeovalley or, where this is absent, into the Tubeiliyat Formation. Southern Jordan lay close to the margin of a Late Ordovician terrestrial ice sheet in Northwest Saudi Arabia, characterised by two major ice advances. These are correlated with the lower and upper palaeovalleys in southern Jordan, interrupted by two subsidiary glacial advances during late stage filling of the lower palaeovalley when ice advanced from the west and northwest. Thus, four ice advances are now recorded from the Late Ordovician glacial record of southern Jordan. Disturbed and deformed green sandstones beneath the upper palaeovalley-fill in the Jebel Ammar area, are confined to the margins of the Hutayya graben, and have been interpreted as structureless glacial loessite or glacial rock flour. Petrographic and textural analyses of the deformed sandstones, their mapped lateral transition into undeformed Tubeiliyat marine sandstones away from the fault zone, and the presence of similar sedimentary structures to those in the pre-glacial marine Tubeiliyat Formation suggest that they are a locally deformed facies equivalent of the Tubeiliyat, not part of the younger glacial deposits. Deformation is attributed to glacially induced crustal stresses and seismic reactivation of pre-existing faults, previously weakened by epeirogenesis, triggering sediment

  20. Probability of Unmixed Young Groundwater (defined using chlorofluorocarbon-11 concentrations and tritium activities) in the Eagle River Watershed Valley-Fill Aquifer, Eagle County, North-Central Colorado, 2006-2007

    Science.gov (United States)

    Rupert, Michael G.; Plummer, Niel

    2009-01-01

    This raster data set delineates the predicted probability of unmixed young groundwater (defined using chlorofluorocarbon-11 concentrations and tritium activities) in groundwater in the Eagle River watershed valley-fill aquifer, Eagle County, North-Central Colorado, 2006-2007. This data set was developed by a cooperative project between the U.S. Geological Survey, Eagle County, the Eagle River Water and Sanitation District, the Town of Eagle, the Town of Gypsum, and the Upper Eagle Regional Water Authority. This project was designed to evaluate potential land-development effects on groundwater and surface-water resources so that informed land-use and water management decisions can be made. This groundwater probability map and its associated probability maps were developed as follows: (1) A point data set of wells with groundwater quality and groundwater age data was overlaid with thematic layers of anthropogenic (related to human activities) and hydrogeologic data by using a geographic information system to assign each well values for depth to groundwater, distance to major streams and canals, distance to gypsum beds, precipitation, soils, and well depth. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Statistical models predicting the probability of elevated nitrate concentrations, the probability of unmixed young water (using chlorofluorocarbon-11 concentrations and tritium activities), and the probability of elevated volatile organic compound concentrations were developed using logistic regression techniques. (3) The statistical models were entered into a GIS and the probability map was constructed.

  1. Late Paleozoic paleofjord in the southernmost Parana Basin (Brazil): Geomorphology and sedimentary fill

    Science.gov (United States)

    Tedesco, Julia; Cagliari, Joice; Coitinho, Julia dos Reis; da Cunha Lopes, Ricardo; Lavina, Ernesto Luiz Correa

    2016-09-01

    In the southernmost part of the Parana Basin, records of the late Paleozoic glaciation occur in a discontinuous form preserved in paleovalley systems excavated in the crystalline basement. This paper addresses one of these paleovalleys, the Mariana Pimentel, which extends over 60 km with NW-SE valley direction and a constant width of 2.5 km. With the objective of demonstrating that the paleovalley worked as a fjord during the glaciation period, its origin as well as sedimentary fill and morphology were analyzed. The paleovalley morphology was obtained through electrical resistivity (electrical sounding and lateral mapping) and mathematical modeling in four transverse sections. The morphology of the paleovalley documented by the U-shape, steady width, and high depth reaching up to 400 m are typical features of modern glacial valleys. The sedimentary facies that fill the base of the paleovalley, such as rhythmites and dropstones with thickness up to 70 m and diamictites with faceted pebbles (up to 5 m thick) are signs of its glacial origin. During the glaciation period, the paleovalley had a connection to the epicontinental sea located to the northwest, extended toward Namibia, and was excavated by glaciers from the highlands of this region. Thus, the evidence attests that the Mariana Pimentel paleovalley was a fjord during the late Paleozoic glaciation. The duration of the late Paleozoic glaciation (which is longer than the Quaternary glaciation), the apatite fission track that suggests erosion up to 4 km thick in the study area, and the lack of preserved hanging valleys in the Mariana Pimentel indicate that the paleovalley once featured a higher dimension. Furthermore, the existence of paleofjords excavated in the border of the basement corroborates the idea of small ice centers controlled by topography during the late Paleozoic glaciation.

  2. Scottish landform examples : The Cairngorms - a pre-glacial upland granite landscape

    OpenAIRE

    Hall, A.M.; Gillespie, M.R.; Thomas, C.W.; Ebert, K.

    2013-01-01

    The Cairngorm massif in NE Scotland (Figure 1) is an excellent example of a preglacial upland landscape formed in granite. Glacial erosion in the mountains has been largely confined to valleys and corries (Rea, 1998) and so has acted to dissect a pre-existing upland (Figure 2). Intervening areas of the massif experienced negligible glacial erosion due to protective covers of cold-based ice (Sugden, 1968) and preserve a wide range of pre-glacial and non-glacial landforms and reg...

  3. Alaska Harbor Seal Glacial Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Floating glacial ice serves as a haul-out substrate for a significant number (10-15%) of Alaskan harbor seals, and thus surveying tidewater glacial fjords is an...

  4. Information on the confinement capability of the facility disposal area at West Valley, New York

    International Nuclear Information System (INIS)

    Nicholson, T.J.; Hurt, R.D.

    1985-12-01

    This report summarizes the previous NRC research studies, NRC licensee source term data and recent DOE site investigations that deal with assessment of the radioactive waste inventory and confinement capability of the Facility Disposal Area (FDA) at West Valley, New York. The radioactive waste inventory for the FDA has a total radioactivity of about 135,000 curies (Ci) and is comprised of H-3 (9,500 Ci), Co-60 (64,000 Ci), SR-90/Y-90 (24,300 Ci), Cs-137/Ba-137m (24,400 Ci), and Pu-241 (13,300 Ci). These wastes are buried in the Lavery Till, a glacial till unit comprised of a clayey silt with very low hydraulic conductivity properties. Recent studies of a tributylphosphate-kerosene plume moving through the shallow ground-water flow system in the FDA indicate a need to better assess the fracture flow components of this system particularly the weathered and fractured Lavery Till unit. The analysis of the deeper ground-water flow system studied by the USGS and NYSGS staffs indicated relatively long pathways and travel times to the accessible environment. Mass wasting, endemic to the glacial-filled valley, contributed to the active slumping in the ravines surrounding the FDA and also need attention. 31 refs., 8 figs., 8 tabs

  5. GLACIER DEGRADATION AND CATASTROPHIC MUDFLOWS ORIGIN FROM THE MODERN GLACIAL-MORAINE BODIES IN THE ELBRUS REGION

    Directory of Open Access Journals (Sweden)

    E. A. Zolotarev

    2012-01-01

    Full Text Available Mechanism of formation of the catastrophic mudflows in different glacial valleys of Elbrus region at the present stage of glacial degradation is described. The important role of the buried ice in the formation of catastrophic mudflows that affected Tyrnyauz in the XX century was revealed as a result of remote monitoring of changes in glacial-moraine complex of Kayarta river. The dynamics of glacial lakes in the Adyl-Su valley in the Bashkara Glacier region was described and probability of their breakthrough was estimated. The quantitative indicators of the dynamics of the landslide in the Kubasanty valley were obtained as a result of remote monitoring, and its influence on the formation of catastrophic mudflows is discovered. Various possible methods of catastrophic mudflows prevention not requiring expensive protective constructions are discussed.

  6. Benchmark soils on alluvial, fluvial and fluvio-glacial formations of the upper-Segre valley Suelos de referencia en formaciones aluviales, fluviales y fluvio-glaciales de la cabecera del río Segre Solos de referência em formações aluviais, fluviais e fluvio-glaciais da cabeceira do rio Segre

    Directory of Open Access Journals (Sweden)

    Rosa María Poch Claret

    2013-07-01

    Full Text Available The upper reaches of the Segre river, flowing through the Pyrenees, offers a variety of geomorphic surfaces that allow us to study soil chronosequences. The objective of this work is to widen the knowledge about the main characteristics and formation processes of some benchmark soils developed on fluvio-glacial, alluvial-fan and terrace materials of Pleistocene and Holocene age related to the Segre river, either siliceous or carbonatic. This knowledge will allow us to identify soil forming processes, commonly found in Mediterranean environments such as carbonate redistribution, clay formation and mobilization and rubefaction, all as functions of parent material and age. Five profiles, ranging from the Lower Pleistocene to the Holocene were classified according to Soil Taxonomy/WRB. The Montferrer profile (Calcic Palexeralf /Calcic Cutanic Luvisol (Chromic is a deep, partly decarbonated soil, with calcium carbonate accumulation in depth covering glacial features. The Torre del Remei profile (Typic Paleustalf /Cutanic Luvisol developed on silicic moraines and shows an extreme clay formation and illuviation. The Alp (Typic Haplustalf /Cutanic Luvisol and Tartera (Petric Calciustept /Petric Calcisol soils are developed on alluvial fans with calcium carbonate sources. The former is partly decarbonated, whilst the latter is rubefacted on top and shows speleothem-like carbonate pendants with superposition of clay illuviation. The youngest profile, Abellerols, (Typic Calciustept /Typic Calcisol shows only a partial decarbonation and calcite accumulation at depth. The results show that soil development is determined by the age of the surface and the source of calcite, either in the parent rock or brought by subsurface flow: clay illuviation is extreme in absence of it. Special morphologies of carbonate pendants are indicators of environmental conditions. The coexistence of clay coatings and secondary calcite can be explained by recarbonatation or by

  7. Using satellite images to monitor glacial-lake outburst floods: Lago Cachet Dos drainage, Chile

    Science.gov (United States)

    Friesen, Beverly A.; Cole, Christopher J.; Nimick, David A.; Wilson, Earl M.; Fahey, Mark J.; McGrath, Daniel J.; Leidich, Jonathan

    2015-01-01

    The U.S. Geological Survey (USGS) is monitoring and analyzing glacial-lake outburst floods (GLOFs) in the Colonia valley in the Patagonia region of southern Chile. A GLOF is a type of flood that occurs when water impounded by a glacier or a glacial moraine is released catastrophically. In the Colonia valley, GLOFs originating from Lago Cachet Dos, which is dammed by the Colonia Glacier, have recurred periodically since 2008. The water discharged during these GLOFs flows under or through the Colonia Glacier, into Lago Colonia and then the Río Colonia, and finally into the Río Baker—Chile's largest river in terms of volume of water.

  8. The George V Land Continental Margin (East Antarctica): new Insights Into Bottom Water Production and Quaternary Glacial Processes from the WEGA project

    Science.gov (United States)

    Caburlotto, A.; de Santis, L.; Lucchi, R. G.; Giorgetti, G.; Damiani, D.; Macri', P.; Tolotti, R.; Presti, M.; Armand, L.; Harris, P.

    2004-12-01

    The George Vth Land represents the ending of one of the largest subglacial basin (Wilkes Basin) of the East Antarctic Ice Sheet (EAIS). Furthermore, its coastal areas are zone of significant production of High Salinity Shelf Water (HSSW). Piston and gravity cores and high resolution echo-sounding (3.5 kHz) and Chirp profiles collected in the frame of the joint Australian and Italian WEGA (WilkEs Basin GlAcial History) project provide new insights into the Quaternary history of the EAIS and the HSSW across this margin: from the sediment record filling and draping valleys and banks along the continental shelf, to the continuous sedimentary section of the mound-channel system on the continental rise. The discovery of a current-lain sediment drift (Mertz Drift, MD) provides clues to understanding the age of the last glacial erosive events, as well as to infer flow-pathways of bottom-water masses changes. The MD shows disrupted, fluted reflectors due to glacial advance during the LGM (Last Glacial Maximum) in shallow water, while undisturbed sediment drift deposited at greater water depth, indicates that during the LGM the ice shelf was floating over the deep sector of the basin. The main sedimentary environment characterising the modern conditions of the continental rise is dominated by the turbiditic processes with a minor contribution of contour currents action. Nevertheless, some areas (WEGA Channel) are currently characterised by transport and settling of sediment through HSSW, originating in the shelf area. This particular environment likely persisted since pre-LGM times. It could indicate a continuous supply of sedimentary material from HSSW during the most recent both glacial and interglacial cycles. This would be consistent with the results obtained in the continental shelf suggesting that the Ice Sheet was not grounding over some parts of the continental shelf. Furthermore, the comparison of the studied area with other Antarctic margins indicate that, contrary

  9. Ongoing hydrothermal heat loss from the 1912 ash-flow sheet, Valley of Ten Thousand Smokes, Alaska

    Science.gov (United States)

    Hogeweg, N.; Keith, T.E.C.; Colvard, E.M.; Ingebritsen, S.E.

    2005-01-01

    The June 1912 eruption of Novarupta filled nearby glacial valleys on the Alaska Peninsula with ash-flow tuff (ignimbrite), and post-eruption observations of thousands of steaming fumaroles led to the name 'Valley of Ten Thousand Smokes' (VTTS). By the late 1980s most fumarolic activity had ceased, but the discovery of thermal springs in mid-valley in 1987 suggested continued cooling of the ash-flow sheet. Data collected at the mid-valley springs between 1987 and 2001 show a statistically significant correlation between maximum observed chloride (Cl) concentration and temperature. These data also show a statistically significant decline in the maximum Cl concentration. The observed variation in stream chemistry across the sheet strongly implies that most solutes, including Cl, originate within the area of the VTTS occupied by the 1912 deposits. Numerous measurements of Cl flux in the Ukak River just below the ash-flow sheet suggest an ongoing heat loss of ???250 MW. This represents one of the largest hydrothermal heat discharges in North America. Other hydrothermal discharges of comparable magnitude are related to heat obtained from silicic magma bodies at depth, and are quasi-steady on a multidecadal time scale. However, the VTTS hydrothermal flux is not obviously related to a magma body and is clearly declining. Available data provide reasonable boundary and initial conditions for simple transient modeling. Both an analytical, conduction-only model and a numerical model predict large rates of heat loss from the sheet 90 years after deposition.

  10. Glacial isostatic uplift of the European Alps

    Science.gov (United States)

    Mey, Jürgen; Scherler, Dirk; Wickert, Andrew D.; Egholm, David L.; Tesauro, Magdala; Schildgen, Taylor F.; Strecker, Manfred R.

    2016-01-01

    Following the last glacial maximum (LGM), the demise of continental ice sheets induced crustal rebound in tectonically stable regions of North America and Scandinavia that is still ongoing. Unlike the ice sheets, the Alpine ice cap developed in an orogen where the measured uplift is potentially attributed to tectonic shortening, lithospheric delamination and unloading due to deglaciation and erosion. Here we show that ∼90% of the geodetically measured rock uplift in the Alps can be explained by the Earth’s viscoelastic response to LGM deglaciation. We modelled rock uplift by reconstructing the Alpine ice cap, while accounting for postglacial erosion, sediment deposition and spatial variations in lithospheric rigidity. Clusters of excessive uplift in the Rhône Valley and in the Eastern Alps delineate regions potentially affected by mantle processes, crustal heterogeneity and active tectonics. Our study shows that even small LGM ice caps can dominate present-day rock uplift in tectonically active regions. PMID:27830704

  11. An example of Alaknanda valley, Garhwal Himalaya, India

    Indian Academy of Sciences (India)

    2014) have been best explained by the geometry .... flows through narrow valley confined by the steep valley slopes. ... valley (figure 3b) which opens up around Srina- ... Method. 4.1 Drainage basin and stream network. Digital Elevation Model (DEM) helps in extracting ... was processed to fill the pits or sinks, and to obtain.

  12. A ∼180,000 years sedimentation history of a perialpine overdeepened glacial trough (Wehntal, N-Switzerland)

    International Nuclear Information System (INIS)

    Anselmetti, F. S.; Drescher-Schneider, R.; Furrer, H.; Graf, H. R.; Lowick, S. E.; Preusser, F.; Riedi, M. A.

    2010-01-01

    A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a ∼ 180 ka old sedimentary succession that provides new insights into the timing and nature of erosion-sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between ∼ 180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called M ammoth peat , previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with paleoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history. (authors)

  13. A {approx}180,000 years sedimentation history of a perialpine overdeepened glacial trough (Wehntal, N-Switzerland)

    Energy Technology Data Exchange (ETDEWEB)

    Anselmetti, F. S. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf (Switzerland); Drescher-Schneider, R. [Institut fuer Pflanzenwissenschaften, Karl-Fanzen-Universitaet Graz, Graz (Austria); Furrer, H. [Palaeontologisches Institut und Museum, Universitaet Zuerich, Zuerich (Switzerland); Graf, H. R. [Matousek, Baumann und Niggli AG, Baden (Switzerland); Lowick, S. E.; Preusser, F. [Institut fuer Geologie, Universitaet Bern, Bern (Switzerland); Riedi, M. A. [Marc A. Riedi, Susenbuehlstrasse 41, Chur (Switzerland)

    2010-11-15

    A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a {approx} 180 ka old sedimentary succession that provides new insights into the timing and nature of erosion-sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between {approx} 180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called {sup M}ammoth peat{sup ,} previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with paleoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history. (authors)

  14. Direct effect of ice sheets on terrestrial bicarbonate, sulphate and base cation fluxes during the last glacial cycle: minimal impact on atmospheric CO2 concentrations

    OpenAIRE

    Tranter, M.; Huybrechts, Philippe; Munhoven, G.; Sharp, M. J.; Brown, G. H.; Jones, I. W.; Hodson, A. J.; Hodgkins, R.; Wadham, J. L.

    2002-01-01

    Chemical erosion in glacial environments is normally a consequence of chemical weathering reactions dominated bysulphide oxidation linked to carbonate dissolution and the carbonation of carbonates and silicates. Solute fluxes from small valley glaciers are usually a linear function of discharge. Representative glacial solute concentrations can be derived from the linear association of solute flux with discharge. These representative glacial concentrations of the major ions are =25% of those i...

  15. Glacial and Quaternary geology of the northern Yellowstone area, Montana and Wyoming

    Science.gov (United States)

    Pierce, Kenneth L.; Licciardi, Joseph M.; Krause, Teresa R.; Whitlock, Cathy

    2014-01-01

    This field guide focuses on the glacial geology and paleoecology beginning in the Paradise Valley and progressing southward into northern Yellowstone National Park. During the last (Pinedale) glaciation, the northern Yellowstone outlet glacier flowed out of Yellowstone Park and down the Yellowstone River Valley into the Paradise Valley. The field trip will traverse the following Pinedale glacial sequence: (1) deposition of the Eightmile terminal moraines and outwash 16.5 ± 1.4 10Be ka in the Paradise Valley; (2) glacial recession of ~8 km and deposition of the Chico moraines and outwash 16.1 ± 1.7 10Be ka; (3) glacial recession of 45 km to near the northern Yellowstone boundary and moraine deposition during the Deckard Flats readjustment 14.2 ± 1.2 10Be ka; and (4) glacial recession of ~37 km and deposition of the Junction Butte moraines 15.2 ± 1.3 10Be ka (this age is a little too old based on the stratigraphic sequence). Yellowstone's northern range of sagebrush-grasslands and bison, elk, wolf, and bear inhabitants is founded on glacial moraines, sub-glacial till, and outwash deposited during the last glaciation. Floods released from glacially dammed lakes and a landslide-dammed lake punctuate this record. The glacial geologic reconstruction was evaluated by calculation of basal shear stress, and yielded the following values for flow pattern in plan view: strongly converging—1.21 ± 0.12 bars (n = 15); nearly uniform—1.04 ± 0.16 bars (n = 11); and strongly diverging—0.84 ± 0.14 bars (n = 16). Reconstructed mass balance yielded accumulation and ablation each of ~3 km3/yr, with glacial movement near the equilibrium line altitude dominated by basal sliding. Pollen and charcoal records from three lakes in northern Yellowstone provide information on the postglacial vegetation and fire history. Following glacial retreat, sparsely vegetated landscapes were colonized first by spruce parkland and then by closed subalpine forests. Regional fire activity

  16. Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

    Science.gov (United States)

    Arauza, Hanna M.; Simms, Alexander R.; Bement, Leland C.; Carter, Brian J.; Conley, Travis; Woldergauy, Ammanuel; Johnson, William C.; Jaiswal, Priyank

    2016-01-01

    Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

  17. Climatic implications of correlated upper Pleistocene glacial and fluvial deposits on the Cinca and Gallego rivers, NE Spain

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Claudia J [Los Alamos National Laboratory; Mcdonald, Eric [NON LANL; Sancho, Carlos [NON LANL; Pena, Jose- Luis [NON LANL

    2008-01-01

    We correlate Upper Pleistocene glacial and fluvial deposits of the Cinca and Gallego River valleys (south central Pyrenees and Ebro basin, Spain) using geomorphic position, luminescence dates, and time-related trends in soil development. The ages obtained from glacial deposits indicate glacial periods at 85 {+-} 5 ka, 64 {+-} 11 ka, and 36 {+-} 3 ka (from glacial till) and 20 {+-} 3 ka (from loess). The fluvial drainage system, fed by glaciers in the headwaters, developed extensive terrace systems in the Cinca River valley at 178 {+-} 21 ka, 97 {+-} 16 ka, 61 {+-} 4 ka, 47 {+-} 4 ka, and 11 {+-} 1 ka, and in the Gallego River valley at 151 {+-} 11 ka, 68 {+-} 7 ka, and 45 {+-} 3 ka. The times of maximum geomorphic activity related to cold phases coincide with Late Pleistocene marine isotope stages and heinrich events. The maximum extent of glaciers during the last glacial occurred at 64 {+-} 11 ka, and the terraces correlated with this glacial phase are the most extensive in both the Cinca (61 {+-} 4 ka) and Gallego (68 {+-} 7 ka) valleys, indicating a strong increase in fluvial discharge and availability of sediments related to the transition to deglaciation. The global Last Glacial Maximum is scarcely represented in the south central Pyrenees owing to dominantly dry conditions at that time. Precipitation must be controlled by the position of the Iberian Peninsula with respect to the North Atlantic atmospheric circulation system. The glacial systems and the associated fluvial dynamic seem sensitive to (1) global climate changes controlled by insolation, (2) North Atlantic thermohaline circulation influenced by freshwater pulses into the North Atlantic, and (3) anomalies in atmospheric circulation in the North Atlantic controlling precipitation on the Iberian peninsula. The model of glacial and fluvial evolution during the Late Pleistocene in northern Spain could be extrapolated to other glaciated mountainous areas in southern Europe.

  18. Cosmogenic evidence for limited local LGM glacial expansion, Denton Hills, Antarctica

    Science.gov (United States)

    Joy, Kurt; Fink, David; Storey, Bryan; De Pascale, Gregory P.; Quigley, Mark; Fujioka, Toshiyuki

    2017-12-01

    The geomorphology of the Denton Hills provides insight into the timing and magnitude of glacial retreats in a region of Antarctica isolated from the influence of the East Antarctic ice sheet. We present 26 Beryllium-10 surface exposure ages from a variety of glacial and lacustrine features in the Garwood and Miers valleys to document the glacial history of the area from 10 to 286 ka. Our data show that the cold-based Miers, Joyce and Garwood glaciers retreated little since their maximum positions at 37.2 ± 6.9 (1σ n = 4), 35.1 ± 1.5 (1σ, n = 3) and 35.6 ± 10.1 (1σ, n = 6) ka respectively. The similar timing of advance of all three glaciers and the lack of a significant glacial expansion during the global LGM suggests a local LGM for the Denton Hills between ca. 26 and 51 ka, with a mean age of 36.0 ± 7.5 (1σ, n = 13) ka. A second cohort of exposure ages provides constraints to the behaviour of Glacial Lake Trowbridge that formerly occupied Miers Valley in the late Pleistocene. These data show active modification of the landscape from ∼20 ka until the withdrawal of ice from the valley mouths, and deposition of Ross Sea Drift, at 10-14 ka.

  19. Glacial Features (Point) - Quad 168 (EPPING, NH)

    Data.gov (United States)

    University of New Hampshire — The Glacial Features (Point) layer describes point features associated with surficial geology. These glacial features include, but are not limited to, delta forsets,...

  20. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  1. Glacial and postglacial geology near Lake Tennyson, Clarence River, New Zealand

    International Nuclear Information System (INIS)

    McCalpin, J.P.

    1992-01-01

    Otiran valley glaciers extended 15 km down the upper Clarence Valley in central Marlborough, South Island, New Zealand. A massive Otiran terminal moraine complex, composed of moraines of three glacial advances, impounds Lake Tennyson. The moraines are early and middle Otiran, and possibly late Otiran-early Aranuian in age, based on relative position and differences in moraine morphology, weathering rinds, and soils. Radiocarbon ages from a tributary (Serpentine Creek) suggest the latest major episode of aggradation in the Clarence Valley was in progress by 11.3 ka, and had ended by 9.2 ka. Postglacial history was dominated by incision of glacial outwash, deposition of small alluvial fans, and landsliding near the trace of the Awatere Fault. Fault scarps of the Awatere Fault and of unnamed parallel splays displace early Otiran moraines up to 19 m and early Holocene terraces up to 2.6 m. (author). 25 refs., 10 figs., 3 tabs

  2. Glacial flour in lacustrine sediments: Records of alpine glaciation in the western U.S.A. during the last glacial interval

    Science.gov (United States)

    Rosenbaum, J. G.; Reynolds, R. L.

    2010-12-01

    glacial-age sediments, but cosmogenic dating (by Laabs et al.) of highly resistant quartzite boulders provide ages from terminal moraines in the Bear River drainage. Glacial flour appears abruptly at ~26 cal ka in Bear Lake, whereas it is present at the base of the Upper Klamath Lake core (~37 cal ka). Both glacial flour records (1) contain millennial-scale variations (uncertainties in chronology prevent precise correlation of these features), (2) attain maxima circa 19 cal ka, and (3) rapidly decline beginning prior to 18 cal ka. At Bear Lake the age of the decline in glacial flour coincides with cosmogenic exposure ages (18.1 - 18.7 ka) of terminal moraines in the upper Bear River valley. This concurrence supports the interpretation that the maximum amount and subsequent decrease in glacial flour are indicative of maximum glacial extent and glacial retreat, respectively, and more generally that increases and decreases in rock flour in these lake sediments represent waxing and waning of glaciers. Laabs, B,J.C., et al., 2007, Chronology of the last glacial maximum in the upper Bear River basin, Utah, Arctic and Alpine Research, v. 39, p. 537 - 548.

  3. The last glacial maximum

    Science.gov (United States)

    Clark, P.U.; Dyke, A.S.; Shakun, J.D.; Carlson, A.E.; Clark, J.; Wohlfarth, B.; Mitrovica, J.X.; Hostetler, S.W.; McCabe, A.M.

    2009-01-01

    We used 5704 14C, 10Be, and 3He ages that span the interval from 10,000 to 50,000 years ago (10 to 50 ka) to constrain the timing of the Last Glacial Maximum (LGM) in terms of global ice-sheet and mountain-glacier extent. Growth of the ice sheets to their maximum positions occurred between 33.0 and 26.5 ka in response to climate forcing from decreases in northern summer insolation, tropical Pacific sea surface temperatures, and atmospheric CO2. Nearly all ice sheets were at their LGM positions from 26.5 ka to 19 to 20 ka, corresponding to minima in these forcings. The onset of Northern Hemisphere deglaciation 19 to 20 ka was induced by an increase in northern summer insolation, providing the source for an abrupt rise in sea level. The onset of deglaciation of the West Antarctic Ice Sheet occurred between 14 and 15 ka, consistent with evidence that this was the primary source for an abrupt rise in sea level ???14.5 ka.

  4. Hydrogeology and simulation of groundwater flow at the Green Valley reclaimed coal refuse site near Terre Haute, Indiana

    Science.gov (United States)

    Bayless, E. Randall; Arihood, Leslie D.; Fowler, Kathleen K.

    2011-01-01

    The Green Valley reclaimed coal refuse site, near Terre Haute, Ind., was mined for coal from 1948 to 1963. Subsurface coal was cleaned and sorted at land surface, and waste material was deposited over the native glacial till. Approximately 2.7 million cubic yards of waste was deposited over 159 acres (92.3 hectares) in tailings ponds and gob piles. During 1993, the Indiana Department of Natural Resources, Division of Reclamation, improved the site by grading gob piles, filling tailings ponds, and covering the refuse with a layer of glacial drift. During 2008, the Division of Reclamation and U.S. Geological Survey initiated a cooperative investigation to characterize the hydrogeology of the site and construct a calibrated groundwater flow model that could be used to simulate the results of future remedial actions. In support of the modeling, a data-collection network was installed at the Green Valley site to measure weather components, geophysical properties, groundwater levels, and stream and seep flow. Results of the investigation indicate that (1) there is negligible overland flow from the site, (2) the prevailing groundwater-flow direction is from northeast to southwest, with a much smaller drainage to the northeast, (3) there is not a direct hydraulic connection between the refuse and West Little Sugar Creek, (4) about 24 percent of the groundwater recharge emerges through seeps, and water from the seeps evaporates or eventually flows to West Little Sugar Creek and the Green Valley Mine Pond, and (5) about 72 percent of groundwater recharge moves vertically downward from the coal refuse into the till and follows long, slow flow paths to eventual dischage points.

  5. Modelling the Effects of Sea-level, Climate Change, Geology, and Tectonism on the Morphology of the Amazon River Valley and its Floodplain

    Science.gov (United States)

    Aalto, R. E.; Cremon, E.; Dunne, T.

    2017-12-01

    How continental-scale rivers respond to climate, geology, and sea level change is not well represented in morphodynamic models. Large rivers respond to influences less apparent in the form and deposits of smaller streams, as the huge scales require long time periods for changes in form and behavior. Tectonic deformation and excavation of resistant deposits can affect low gradient continental-scale rivers, thereby changing flow pathways, channel slope and sinuosity, along-stream patterns of sediment transport capacity, channel patterns, floodplain construction, and valley topography. Nowhere are such scales of morphodynamic response grander than the Amazon River, as described in papers by L.A.K. Mertes. Field-based understanding has improved over the intervening decades, but mechanistic models are needed to simulate and synthesize key morphodynamic components relevant to the construction of large river valleys, with a focus on the Amazon. The Landscape-Linked Environmental Model (LLEM) utilizes novel massively parallel computer architectures to simulate multiple-direction flow, sediment transport, deposition, and incision for exceptionally large (30-80 million nodes per compute unit) lowland dispersal systems. LLEM represents key fluvial processes such as bed and bar deposition, lateral and vertical erosion/incision, levee and floodplain construction, floodplain hydrology, `badlands dissection' of weak sedimentary deposits during falling sea level, tectonic and glacial-isostatic deformation, and provides a 3D record of created stratigraphy and underlying bedrock. We used LLEM to simulate the development of the main valley of the Amazon over the last million years, exploring the propagation of incision waves and system dissection during glacial lowstands, followed by rapid valley filling and extreme lateral mobility of channels during interglacials. We present metrics, videos, and 3D fly-throughs characterizing how system development responds to key assumptions

  6. Valley Fever

    Science.gov (United States)

    ... valley fever. These fungi are commonly found in soil in specific regions. The fungi's spores can be stirred into the air by ... species have a complex life cycle. In the soil, they grow as a mold with long filaments that break off into airborne ...

  7. Geologic map of the upper Arkansas River valley region, north-central Colorado

    Science.gov (United States)

    Kellogg, Karl S.; Shroba, Ralph R.; Ruleman, Chester A.; Bohannon, Robert G.; McIntosh, William C.; Premo, Wayne R.; Cosca, Michael A.; Moscati, Richard J.; Brandt, Theodore R.

    2017-11-17

    This 1:50,000-scale U.S. Geological Survey geologic map represents a compilation of the most recent geologic studies of the upper Arkansas River valley between Leadville and Salida, Colorado. The valley is structurally controlled by an extensional fault system that forms part of the prominent northern Rio Grande rift, an intra-continental region of crustal extension. This report also incorporates new detailed geologic mapping of previously poorly understood areas within the map area and reinterprets previously studied areas. The mapped region extends into the Proterozoic metamorphic and intrusive rocks in the Sawatch Range west of the valley and the Mosquito Range to the east. Paleozoic rocks are preserved along the crest of the Mosquito Range, but most of them have been eroded from the Sawatch Range. Numerous new isotopic ages better constrain the timing of both Proterozoic intrusive events, Late Cretaceous to early Tertiary intrusive events, and Eocene and Miocene volcanic episodes, including widespread ignimbrite eruptions. The uranium-lead ages document extensive about 1,440-million years (Ma) granitic plutonism mostly north of Buena Vista that produced batholiths that intruded an older suite of about 1,760-Ma metamorphic rocks and about 1,700-Ma plutonic rocks. As a result of extension during the Neogene and possibly latest Paleogene, the graben underlying the valley is filled with thick basin-fill deposits (Dry Union Formation and older sediments), which occupy two sub-basins separated by a bedrock high near the town of Granite. The Dry Union Formation has undergone deep erosion since the late Miocene or early Pliocene. During the Pleistocene, ongoing steam incision by the Arkansas River and its major tributaries has been interrupted by periodic aggradation. From Leadville south to Salida as many as seven mapped alluvial depositional units, which range in age from early to late Pleistocene, record periodic aggradational events along these streams that are

  8. The Muralla Pircada: an ancient Andean debris flow retention dam, Santa Rita B archaeological site, Chao Valley, Northern Peru

    Science.gov (United States)

    Brooks, William E.; Willett, Jason C.; Kent, Jonathan D.; Vasquez, Victor; Rosales, Teresa

    2005-01-01

    Debris flows caused by El Niño events, earthquakes, and glacial releases have affected northern Perú for centuries. The Muralla Pircada, a northeast-trending, 2.5 km long stone wall east of the Santa Rita B archaeological site (Moche-Chimú) in the Chao Valley, is field evidence that ancient Andeans recognized and, more importantly, attempted to mitigate the effects of debris flows. The Muralla is upstream from the site and is perpendicular to local drainages. It is 1–2 m high, up to 5 m wide, and is comprised of intentionally-placed, well-sorted, well-rounded, 20–30 cm cobbles and boulders from nearby streams. Long axes of the stones are gently inclined and parallel local drainage. Case-and-fill construction was used with smaller cobbles and pebbles used as fill. Pre-Muralla debris flows are indicated by meter-sized, angular boulders that were incorporated in-place into construction of the dam and are now exposed in breeches in the dam. Post-Muralla debris flows in the Chao Valley are indicated by meter-sized, angular boulders that now abut the retention dam.

  9. Late-Quaternary glacial to postglacial sedimentation in three adjacent fjord-lakes of the Québec North Shore (eastern Canadian Shield)

    Science.gov (United States)

    Poiré, Antoine G.; Lajeunesse, Patrick; Normandeau, Alexandre; Francus, Pierre; St-Onge, Guillaume; Nzekwe, Obinna P.

    2018-04-01

    High-resolution swath bathymetry imagery allowed mapping in great detail the sublacustrine geomorphology of lakes Pentecôte, Walker and Pasteur, three deep adjacent fjord-lakes of the Québec North Shore (eastern Canada). These sedimentary basins have been glacio-isostatically uplifted to form deep steep-sided elongated lakes. Their key geographical position and limnogeological characteristics typical of fjords suggest exceptional potential for long-term high-resolution paleoenvironmental reconstitutions. Acoustic subbottom profiles acquired using a bi-frequency Chirp echosounder (3.5 & 12 kHz), together with cm- and m-long sediment core data, reveal the presence of four acoustic stratigraphic units. The acoustic basement (Unit 1) represents the structural bedrock and/or the ice-contact sediments of the Laurentide Ice Sheet and reveals V-shaped bedrock valleys at the bottom of the lakes occupied by ice-loaded sediments in a basin-fill geometry (Unit 2). Moraines observed at the bottom of lakes and in their structural valleys indicate a deglaciation punctuated by short-term ice margin stabilizations. Following ice retreat and their isolation, the fjord-lakes were filled by a thick draping sequence of rhythmically laminated silts and clays (Unit 3) deposited during glaciomarine and/or glaciolacustrine settings. These sediments were episodically disturbed by mass-movements during deglaciation due to glacial-isostatic rebound. AMS 14C dating reveal that the transition between deglaciation of the lakes Pentecôte and Walker watersheds and the development of para- and post-glacial conditions occurred around 8000 cal BP. The development of the lake-head river delta plain during the Holocene provided a constant source of fluvial sediment supply to the lakes and the formation of turbidity current bedforms on the sublacustrine delta slopes. The upper sediment succession (i.e., ∼4-∼6.5 m) consists of a continuous para-to post-glacial sediment drape (Unit 4) that contains

  10. Glacial History of Southernmost South America and Implications for Movement of the Westerlies and Antarctic Frontal Zone

    Science.gov (United States)

    Kaplan, M. R.; Fogwill, C. J.; Hulton, N. R.; Sugden, D. E.; Peter, K. W.

    2004-12-01

    The ~1 Myr glacial geologic record in southern South American is one of the few available terrestrial paleoclimate proxies at orbital and suborbital time scales in the middle latitudes of the Southern Hemisphere. Presently, southernmost Patagonia lies about 3\\deg north of the Antarctic frontal zone and within the middle latitude westerlies and the climate is controlled by the surrounding maritime conditions. Thus, the long-term glacial record provides insight into the history of climatic boundaries over the middle and high latitude southern ocean, including the upwind SE Pacific Ocean, tectonic-glacial evolution of the Andes, and global climate. To date, cosmogenic nuclide and 14C dating have focused on glacial fluctuations between 51 and 53\\deg S (Torres del Paine to northern Tierra del Fuego) during the last glacial cycle, including the late glacial period. At least 4 advances occurred between ca. 25 and 17 ka, with the maximum expansion of ice ca. 25-24 ka. Major deglaciation commenced after ca. 17.5 ka, which was interrupted by a major glacial-climate event ca. 14-12 ka. Modelling experiments suggest that the ice mass needed to form the glacial maximum moraines required about a 6\\deg cooling and a slight drying relative to the present. Such a fundamental temperature reduction, despite high summer isolation, strongly suggests northward movement of the westerlies and the polar front on millennial timescales. The Patagonian record also indicates that on orbital timescales equatorward movement of climate boundaries and glacial growth was in phase with major Northern Hemisphere ice volume change, despite high local summer insolation. At suborbital timescales, the picture is more complex. While major facets of the last glacial maximum appear to be in phase between the hemispheres, at least some late glacial events may be in step with Antarctic climate change. Present and future research will further constrain the timing of glacial events over the last 1 Myr and

  11. Microfabric and Structures in Glacial Ice

    Science.gov (United States)

    Monz, M.; Hudleston, P. J.

    2017-12-01

    Similar to rocks in active orogens, glacial ice develops both structures and fabrics that reflect deformation. Crystallographic preferred orientation (CPO), associated with mechanical anisotropy, develops as ice deforms, and as in rock, directly reflects the conditions and mechanisms of deformation and influences the overall strength. This project aims to better constrain the rheologic properties of natural ice through microstructural analysis and to establish the relationship of microfabric to macroscale structures. The focus is on enigmatic fabric patterns found in coarse grained, "warm" (T > -10oC) ice deep in ice sheets and in valley glaciers. Deformation mechanisms that produce such patterns are poorly understood. Detailed mapping of surface structures, including bedding, foliation, and blue bands (bubble-free veins of ice), was done in the ablation zone of Storglaciären, a polythermal valley glacier in northern Sweden. Microstructural studies on samples from a transect across the ablation zone were carried out in a cold room. Crystal size was too large for use of electron backscattered diffraction to determine CPO, therefore a Rigsby universal stage, designed specifically for ice, was used. In thick and thin sections, recrystallized grains are locally variable in both size (1mm-7cm in one thin section) and shape and clearly reflect recrystallization involving highly mobile grain boundaries. Larger crystals are often branching, and appear multiple times throughout one thin section. There is a clear shape preferred orientation that is generally parallel with foliation defined by bubble alignment and concentration. Locally, there appears to be an inverse correlation between bubble concentration and smoothness of grain boundaries. Fabric in samples that have undergone prolonged shear display roughly symmetrical multimaxima patterns centered around the pole to foliation. The angular distances between maxima suggest a possible twin relationship that may have

  12. An attempt at determining Des of glacial sediments using different luminescence methods

    International Nuclear Information System (INIS)

    Ou Xianjiao; Lai Zhongping; Zeng Lanhua

    2013-01-01

    Background: Absolute dating is the key technical issue of Quaternary glacial research. Optically stimulated luminescence (OSL) has been increasingly applied to Quaternary glacial dating in recent years. However, problems such as insufficient bleaching, low luminescence sensitivity, high thermal transfer effect, etc, still remain. Purpose: In order to investigate the applicability of equivalent dose (D e ) determination of glacial sediments by different OSL methods, six samples were collected from the Yingpu Valley of eastern Qinghai-Tibetan Plateau (two samples from modern glacial sediments, three from moraines and glacial terrace attributed to Neoglacial and one from a moraine attributed to the last glaciation). Methods: The D e s were determined by SAR combined SGC technique, using three methods: quartz large aliquot (6 mm) BSL, small aliquot (2/3 mm) BSL and polymineral IRSL. Results: D e s determined by SGC are consistent with D e s determined by SAR protocol. Comparison of three methods shows that IRSL D e >large aliquot BSL D e >small aliquot BSL D e . D e s of polymineral IRSL are obviously higher than quartz BSL. Conclusions: It is obviously that feldspar is more difficult to reset than quartz, thus is not suitable for dating glacial sediments in this region. Quartz large aliquot method is suitable for well bleached glacial samples. Due to the low luminescence sensitivity of quartz, small aliquot method showed poor luminescence characteristics. Moreover, this method cannot distinguish the poor bleached grains in this measurement. However, it is possible that quartz small aliquot, even single grain method could be used to date older or brighter glacial samples. More works are required to solve the problems we have encountered in dating low sensitivity glacial sediments. (authors)

  13. About Dental Amalgam Fillings

    Science.gov (United States)

    ... and Medical Procedures Dental Devices Dental Amalgam About Dental Amalgam Fillings Share Tweet Linkedin Pin it More ... should I have my fillings removed? What is dental amalgam? Dental amalgam is a dental filling material ...

  14. Geomorphic controls on Pleistocene knickpoint migration in Alpine valleys

    Science.gov (United States)

    Leith, Kerry; Fox, Matt; Moore, Jeffrey R.; Brosda, Julian; Krautblatter, Michael; Loew, Simon

    2014-05-01

    Recent insights into sub-glacial bedrock stress conditions suggest that the erosional efficiency of glaciers may reduce markedly following a major erosional cycle [Leith et al., 2013]. This implies that the formation of large glacial valleys within the Alps is likely to have occurred shortly after the onset of 100 ky glacial-interglacial cycles (at the mid-Pleistocene Revolution (MPR)). The majority of landscape change since this time may have therefore been driven by sub-aerial processes. This hypothesis is supported by observations of hillslope and channel morphology within Canton Valais (Switzerland), where major tributary valleys display a common morphology along their length, hinting at a shared geomorphic history. Glaciers currently occupy the headwaters of many catchments, while the upper reaches of rivers flow across extensive alluvial planes before abruptly transitioning to steep channels consisting of mixed bedrock and talus fan deposits. The rivers then converge to flow out over the alluvial plane of the Rhone Valley. Characteristically rough topographies within the region are suggested to mark the progressive transition from a glacial to fluvially-dominated landscape, and correlate well with steepened river channel sections determined from a 2.5 m resolution LiDAR DEM. We envisage a landscape in which ongoing tectonic uplift drives the emergence of Alpine bedrock through massive sedimentary valley infills (currently concentrated in the Rhone Valley), whose elevation is fixed by the consistent fluvial baselevel at Lake Geneva. As fluvial incision ceases at the onset of glaciation, continued uplift causes the formation of knickpoints at the former transition from bedrock to sedimentary infill. These knickpoints will then propagate upstream during subsequent interglacial periods. By investigating channel morphologies using an approach based on the steady-state form of the stream power equation, we can correlate steepened channel reaches (degraded

  15. Origin, Extent, and Thickness of Quaternary Geologic Units in the Willamette Valley, Oregon

    Science.gov (United States)

    O'Connor, Jim E.; Sarna-Wojcicki, Andrei M.; Wozniak, Karl C.; Polette, Danial J.; Fleck, Robert J.

    2001-01-01

    Stratigraphic and chronologic information collected for Quaternary deposits in the Willamette Valley, Oregon, provides a revised stratigraphic framework that serves as a basis for a 1:250,000-scale map, as well as for thickness estimates of widespread Quaternary geologic units. We have mapped 11 separate Quaternary units that are differentiated on the basis of stratigraphic, topographic, pedogenic, and hydrogeologic properties. In summation, these units reflect four distinct episodes in the Quaternary geologic development of the Willamette Valley: 1) Fluvial sands and gravels that underlie terraces flanking lowland margins and tributary valleys were probably deposited between 2.5 and 0.5 million years ago. They are the oldest widespread surficial Quaternary deposits in the valley. Their present positions and preservation are undoubtedly due to postdepositional tectonic deformation - either by direct tectonic uplift of valley margins, or by regional tectonic controls on local base level. 2) Tertiary and Quaternary excavation or tectonic lowering of the Willamette Valley accommodated as much as 500 m (meters) of lacustrine and fluvial fill. Beneath the lowland floor, much of the upper 10 to 50 m of fill is Quaternary sand and gravel deposited by braided channel systems in subhorizontal sheets 2 to 10 m thick. These deposits grade to gravel fans 40 to 100 m thick where major Cascade Range rivers enter the valley and are traced farther upstream as much thinner valley trains of coarse gravel. The sand and gravel deposits have ages that range from greater than 420,000 to about 12,000 years old. A widely distributed layer of sand and gravel deposited at about 12 ka (kiloannum, thousands of years before the present) is looser and probably more permeable than older sand and gravel. Stratigraphic exposures and drillers' logs indicate that this late Pleistocene unit is mostly between 5 and 20 m thick where it has not been subsequently eroded by the Willamette River and its

  16. Fundamental and higher two-dimensional resonance modes of an Alpine valley

    Science.gov (United States)

    Ermert, Laura; Poggi, Valerio; Burjánek, Jan; Fäh, Donat

    2014-08-01

    We investigated the sequence of 2-D resonance modes of the sediment fill of Rhône Valley, Southern Swiss Alps, a strongly overdeepened, glacially carved basin with a sediment fill reaching a thickness of up to 900 m. From synchronous array recordings of ambient vibrations at six locations between Martigny and Sion we were able to identify several resonance modes, in particular, previously unmeasured higher modes. Data processing was performed with frequency domain decomposition of the cross-spectral density matrices of the recordings and with time-frequency dependent polarization analysis. 2-D finite element modal analysis was performed to support the interpretation of processing results and to investigate mode shapes at depth. In addition, several models of realistic bedrock geometries and velocity structures could be used to qualitatively assess the sensitivity of mode shape and particle motion dip angle to subsurface properties. The variability of modal characteristics due to subsurface properties makes an interpretation of the modes purely from surface observations challenging. We conclude that while a wealth of information on subsurface structure is contained in the modal characteristics, a careful strategy for their interpretation is needed to retrieve this information.

  17. 20th-century glacial-marine sedimentation in Vitus Lake, Bering Glacier, Alaska, U.S.A.

    Science.gov (United States)

    Molnia, B.F.; Post, A.; Carlson, P.R.

    1996-01-01

    Vitus Lake, the ice-marginal basin at the southeastern edge of Bering Glacier, Alaska, U.S.A., is a site of modern, rapid, glacial-marine sedimentation. Rather than being a fresh-water lake, Vitus Lake is a tidally influenced, marine to brackish embayment connected to the Pacific Ocean by an inlet, the Seal River. Vitus Lake consists of five deep bedrock basins, separated by interbasinal highs. Glacial erosion has cut these basins as much as 250 m below sea level. High-resolution seismic reflection surveys conducted in 1991 and 1993 of four of Vitus Lake's basins reveal a complex, variable three-component acoustic stratigraphy. Although not fully sampled, the stratigraphy is inferred to be primarily glacial-marine units of (1) basal contorted and deformed glacial-marine and glacial sediments deposited by basal ice-contact processes and submarine mass-wasting; (2) acoustically well-stratified glacial-marine sediment, which unconformably overlies the basal unit and which grades upward into (3) acoustically transparent or nearly transparent glacial-marine sediment. Maximum thicknesses of conformable glacial-marine sediment exceed 100 m. All of the acoustically transparent and stratified deposits in Vitus Lake are modern in age, having accumulated between 1967 and 1993. The basins where these three-part sequences of "present-day" glacial-marine sediment are accumulating are themselves cut into older sequences of stratified glacial and glacial-marine deposits. These older units outcrop on the islands in Vitus Lake. In 1967, as the result of a major surge, glacier ice completely filled all five basins. Subsequent terminus retreat, which continued through August 1993, exposed these basins, providing new locations for glacial-marine sediment accumulation. A correlation of sediment thicknesses measured from seismic profiles at specific locations within the basins, with the year that each location became ice-free, shows that the sediment accumulation at some locations

  18. Landscape history and man-induced landscape changes in the young morainic area of the North European Plain — a case study from the Bäke Valley, Berlin

    Science.gov (United States)

    Böse, Margot; Brande, Arthur

    2010-10-01

    The Bäke creek valley is part of the young morainic area in Berlin. Its origin is related to meltwater flow and dead-ice persistence resulting in a valley with a lake-creek system. During the Late Glacial, the slopes of the valley were affected by solifluction. A Holocene brown soil developed in this material, whereas parts of the lakes were filled with limnic-telmatic sediments. The excavation site at Goerzallee revealed Bronze Age and Iron Age burial places at the upper part of the slope, as well as a fireplace further downslope, but the slope itself remained stable. Only German settlements in the 12th and 13th centuries changed the processes in the creek-lake system: the construction of water mills created a retention system with higher ground water levels in the surrounding areas. On the other hand, deforestation on the till plain and on the slope triggered erosion. Therefore, in medieval time interfingering organic sediments and sand layers were deposited in the lower part of the slope on top of the Holocene soil. The new soil which formed on top of these sediments was transformed by ploughing until the 19th century. In 1905/06 the lower part of the slope was reshaped by the construction of the Teltow Canal, following the valley of the former Bäke creek. Finally, the whole area was levelled by infill after World War II.

  19. Hillslope failure and paraglacial reworking of sediments in response to glacier retreat, Fox Valley, New Zealand.

    Science.gov (United States)

    McColl, Samuel T.; Fuller, Ian C.; Anderson, Brian; Tate, Rosie

    2017-04-01

    Climate and glacier fluctuations influence sediment supply to glacier forelands, which in turn influences down-valley hazards to infrastructure and tourism within glacier forelands. At Fox Glacier, one of New Zealand's most iconic and popular glaciers, rapid retreat has initiated a range of hillslope and valley floor responses, that present a cascade of hazards and changes that need to be carefully managed. Fox Glacier has retreated many kilometres historically, with 2.6 km of retreat since the mid-20th century, and a phase of rapid retreat of 50-340 m per year since 2009. To study the system response to past and ongoing glacial retreat at the Fox valley, morphological changes are being observed using time-lapse photography and the annual collection of high-resolution digital elevation models (DEMs) and orthophoto mosaics. The DEMs are being produced using Structure from Motion photogrammetry from UAV/RPAS and helicopter platforms, and are being used, along with manual ground surveying, to produce ground surface change models (DoDs; DEMs of Difference) and sediment budgets for the valley. Results from time-lapse photography and DoDs show that glacial retreat has initiated destabilisation and (mostly chronic) mass movement of surficial glacial sediments on the valley slopes near the glacier terminus. Alluvial fans farther down valley are actively growing, reworking glacial and landslide sediments from tributary catchments. These paraglacial sediments being delivered to the proglacial river from the glacier terminus and alluvial fans are driving aggradation of the valley floor of decimetres to metres per year and maintaining a highly dynamic braid plain. Valley floor changes also include the melting of buried dead ice, which are causing localised subsidence at the carpark and one of the alluvial fans. The unstable slopes and active debris fans, aggrading and highly active river channel, ground subsidence, add to the spectacle but also the hazards of the Fox valley

  20. Geological and seismic evaluation of a Lower Mannville valley system; Alderson Prospect, Rolling Hills, southeastern Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, J.C.; Lawton, D.C.; Gunn, J.D.

    1987-09-01

    A Lower Mannville valley complex cutting into Jurassic and Mississippian strata in southeastern Alberta was identified on a conventional seismic section. The valley was drilled and a twenty metre core of muddy sandstone was recovered from the target interval. Oil staining was visible within the core but tests showed only muddy water. In contrast, thin sands adjacent to the channel tested up to 300 m/sup 3//day gas and 800 m oil. Sediments adjacent to the valley are interpreted as contemporaneous levee splay deposits of a channel that occupied the valley, whereas the muddy sandstones within the channel represent either a fine grained point bar, or an abandoned channel-fill deposit. In the latter case, coarse grained, sandy, point bar deposits can be expected to occur elsewhere in the channel system. Oil is trapped in crevasse splay deposits draped over a local Mississippian high, but not in the valley because of poor reservoir quality of the channel sandstone. The internal geometry of the valley fill cannot be resolved directly from the seismic data because of the small size of the channel. However, the geometry of reflections from sediments directly above the valley shows variation in the fill and implies that, at the test location, the valley fill is an abandoned channel deposit. It is proposed here that reflection geometry above Lower Mannville valleys can provide a means of determining the type of valley fill. 11 figs., 1 tab., 29 illus.

  1. Origin of last-glacial loess in the western Yukon-Tanana Upland, central Alaska, USA

    Science.gov (United States)

    Muhs, Daniel; Pigati, Jeffrey S.; Budahn, James R.; Skipp, Gary L.; Bettis, E. Arthur; Jensen, Britta

    2018-01-01

    Loess is widespread over Alaska, and its accumulation has traditionally been associated with glacial periods. Surprisingly, loess deposits securely dated to the last glacial period are rare in Alaska, and paleowind reconstructions for this time period are limited to inferences from dune orientations. We report a rare occurrence of loess deposits dating to the last glacial period, ~19 ka to ~12 ka, in the Yukon-Tanana Upland. Loess in this area is very coarse grained (abundant coarse silt), with decreases in particle size moving south of the Yukon River, implying that the drainage basin of this river was the main source. Geochemical data show, however, that the Tanana River valley to the south is also a likely distal source. The occurrence of last-glacial loess with sources to both the south and north is explained by both regional, synoptic-scale winds from the northeast and opposing katabatic winds that could have developed from expanded glaciers in both the Brooks Range to the north and the Alaska Range to the south. Based on a comparison with recent climate modeling for the last glacial period, seasonality of dust transport may also have played a role in bringing about contributions from both northern and southern sources.

  2. Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

    Directory of Open Access Journals (Sweden)

    A. D. Wickert

    2016-11-01

    Full Text Available Over the last glacial cycle, ice sheets and the resultant glacial isostatic adjustment (GIA rearranged river systems. As these riverine threads that tied the ice sheets to the sea were stretched, severed, and restructured, they also shrank and swelled with the pulse of meltwater inputs and time-varying drainage basin areas, and sometimes delivered enough meltwater to the oceans in the right places to influence global climate. Here I present a general method to compute past river flow paths, drainage basin geometries, and river discharges, by combining models of past ice sheets, glacial isostatic adjustment, and climate. The result is a time series of synthetic paleohydrographs and drainage basin maps from the Last Glacial Maximum to present for nine major drainage basins – the Mississippi, Rio Grande, Colorado, Columbia, Mackenzie, Hudson Bay, Saint Lawrence, Hudson, and Susquehanna/Chesapeake Bay. These are based on five published reconstructions of the North American ice sheets. I compare these maps with drainage reconstructions and discharge histories based on a review of observational evidence, including river deposits and terraces, isotopic records, mineral provenance markers, glacial moraine histories, and evidence of ice stream and tunnel valley flow directions. The sharp boundaries of the reconstructed past drainage basins complement the flexurally smoothed GIA signal that is more often used to validate ice-sheet reconstructions, and provide a complementary framework to reduce nonuniqueness in model reconstructions of the North American ice-sheet complex.

  3. Glacial lakes in Austria - Distribution and formation since the Little Ice Age

    Science.gov (United States)

    Buckel, J.; Otto, J. C.; Prasicek, G.; Keuschnig, M.

    2018-05-01

    Glacial lakes constitute a substantial part of the legacy of vanishing mountain glaciation and act as water storage, sediment traps and sources of both natural hazards and leisure activities. For these reasons, they receive growing attention by scientists and society. However, while the evolution of glacial lakes has been studied intensively over timescales tied to remote sensing-based approaches, the longer-term perspective has been omitted due a lack of suitable data sources. We mapped and analyzed the spatial distribution of glacial lakes in the Austrian Alps. We trace the development of number and area of glacial lakes in the Austrian Alps since the Little Ice Age (LIA) based on a unique combination of a lake inventory and an extensive record of glacier retreat. We find that bedrock-dammed lakes are the dominant lake type in the inventory. Bedrock- and moraine-dammed lakes populate the highest landscape domains located in cirques and hanging valleys. We observe lakes embedded in glacial deposits at lower locations on average below 2000 m a.s.l. In general, the distribution of glacial lakes over elevation reflects glacier erosional and depositional dynamics rather than the distribution of total area. The rate of formation of new glacial lakes (number, area) has continuously accelerated over time with present rates showing an eight-fold increase since LIA. At the same time the total glacier area decreased by two-thirds. This development coincides with a long-term trend of rising temperatures and a significant stepping up of this trend within the last 20 years in the Austrian Alps.

  4. Sodium fill of FFTF

    International Nuclear Information System (INIS)

    Waldo, J.B.; Greenwell, R.K.; Keasling, T.A.; Collins, J.R.; Klos, D.B.

    1980-02-01

    With construction of the Fast Flux Test Facility (FFTF) completed, the first major objective in the startup program was to fill the sodium systems. A sodium fill sequence was developed to match construction completion, and as systems became available, they were inerted, preheated, and filled with sodium. The secondary sodium systems were filled first while dry refueling system testing was in progress in the reactor vessel. The reactor vessel and the primary loops were filled last. This paper describes the methods used and some of the key results achieved for this major FFTF objective

  5. Geomorphological hazards in Swat valley, Pakistan

    International Nuclear Information System (INIS)

    Usman, A.

    1999-01-01

    This study attempts to describe, interpret and analyze, in depth, the varied geomorphological hazards and their impacts prevailing in the swat valley locate in the northern hilly and mountainous regions of Pakistan. The hills and mountains re zones of high geomorphological activity with rapid rates of weathering, active tectonic activities, abundant precipitation, rapid runoff and heavy sediment transport. Due to the varied topography, lithology, steep slope, erodible soil, heavy winter snowfall and intensive rainfall in the spring and summer seasons, several kinds of geomorphological hazards, such as geomorphic gravitational hazards, Fluvial hazards, Glacial hazards, Geo tectonic hazards, are occurring frequently in swat valley. Amongst them, geomorphic gravitational hazards, such as rock fall rock slide, debris slide mud flow avalanches, are major hazards in mountains and hills while fluvial hazards and sedimentation are mainly confined to the alluvial plain and lowlands of the valley. The Getechtonic hazards, on the other hand, have wide spread distribution in the valley the magnitude and occurrence of each king of hazard is thus, varied according to intensity of process and physical geographic environment. This paper discusses the type distribution and damage due to the various geomorphological hazards and their reduction treatments. The study would to be of particular importance and interest to both natural and social scientists, as well as planner, environmentalists and decision-makers for successful developmental interventions in the region. (author)

  6. Hydrochemistry of the Mahomet Bedrock Valley Aquifer, East-Central Illinois: indicators of recharge and ground-water flow

    Science.gov (United States)

    Panno, S.V.; Hackley, Keith C.; Cartwright, K.; Liu, Chao-Li

    1994-01-01

    A conceptual model of the ground-water flow and recharge to the Mahomet Bedrock Valley Aquifer (MVA), east-central Illinois, was developed using major ion chemistry and isotope geochemistry. The MVA is a 'basal' fill in the east-west trending buried bedrock valley composed of clean, permeable sand and gravel to thicknesses of up to 61 m. It is covered by a thick sequence of glacial till containing thinner bodies of interbedded sand and gravel. Ground water from the MVA was found to be characterized by clearly defined geochemical regions with three distinct ground-water types. A fourth ground-water type was found at the confluence of the MVA and the Mackinaw Bedrock Valley Aquifer (MAK) to the west. Ground water in the Onarga Valley, a northeastern tributary of the MVA, is of two types, a mixed cation-SO42- type and a mixed cation-HCO3- type. The ground water is enriched in Na+, Ca2+, Mg2+, and SO42- which appears to be the result of an upward hydraulic gradient and interaction of deeper ground water with oxidized pyritic coals and shale. We suggest that recharge to the Onarga Valley and overlying aquifers is 100% from bedrock (leakage) and lateral flow from the MVA to the south. The central MVA (south of the Onarga Valley) is composed of relatively dilute ground water of a mixed cation-HCO3- type, with low total dissolved solids, and very low concentrations of Cl- and SO42-. Stratigraphic relationships of overlying aquifers and ground-water chemistry of these and the MVA suggest recharge to this region of the MVA (predominantly in Champaign County) is relatively rapid and primarily from the surface. Midway along the westerly flow path of the MVA (western MVA), ground water is a mixed cation-HCO3- type with relatively high Cl-, where Cl- increases abruptly by one to ??? two orders of magnitude. Data suggest that the increase in Cl- is the result of leakage of saline ground water from bedrock into the MVA. Mass-balance calculations indicate that approximately 9.5% of

  7. Geochemical Weathering in Glacial and Proglacial Environments

    Science.gov (United States)

    Tranter, M.

    2003-12-01

    solution, typically monitored by electrical conductivity, is often inverse with discharge on both a diurnal and a seasonal basis at lower latitudes, but ismore complex at higher latitudes (Figure 1, Figure 2 and Figure 3). Figure 1, Figure 2 and Figure 3 also show that the total flux of glacial solutes is usually dominated by fluxes associated with high discharge, dilute waters. The chemical weathering reactions that are inferred to occur from the field studies have been supported, in part, by controlled laboratory studies (e.g., Brown et al., 1993a). Recent stable-isotope studies have reported the key involvement of microbial processes in certain regions of the glacier bed ( Bottrell and Tranter, 2002), and these processes are yet to be incorporated in lab-based chemical weathering studies. (14K)Figure 1. (a) The temporal variation of discharge and in non-sea-salt calcium (*Ca2+) concentration in runoff from Haut Glacier d'Arolla, a small, warm-based, valley glacier in the Swiss Alps, during 1989 (Brown et al., 1993a). (b) The temporal variation in *Ca2+ flux from Haut Glacier d'Arolla during 1989. Maximum fluxes are associated with higher discharge waters. (9K)Figure 2. (a) The temporal variation of discharge (Q) and non-sea-salt *Ca2+ concentration in runoff from Manitsoq Glacier, a small outlet glacier on the SW margin of the Greenland Ice Sheet, during 1999. The glacier is warm based, but has a cold-based margin during the winter and early ablation season, so displays polythermal-based hydrological features (Skidmore et al., in preparation). (b) The temporal variation in *Ca2+ flux from Manitsoq Glacier during 1999. Maximum flux is associated with an early season "outburst" event, where longer stored subglacial water first exits the glacier. Otherwise, maximum fluxes are associated with higher discharge waters. (10K)Figure 3. (a) The temporal variation of discharge and *Ca2+ concentration in runoff from Scott Turnerbreen, a small, cold-based, valley glacier on

  8. Differences in Bacterial Diversity and Communities Between Glacial Snow and Glacial Soil on the Chongce Ice Cap, West Kunlun Mountains.

    Science.gov (United States)

    Yang, Guang Li; Hou, Shu Gui; Le Baoge, Ri; Li, Zhi Guo; Xu, Hao; Liu, Ya Ping; Du, Wen Tao; Liu, Yong Qin

    2016-11-04

    A detailed understanding of microbial ecology in different supraglacial habitats is important due to the unprecedented speed of glacier retreat. Differences in bacterial diversity and community structure between glacial snow and glacial soil on the Chongce Ice Cap were assessed using 454 pyrosequencing. Based on rarefaction curves, Chao1, ACE, and Shannon indices, we found that bacterial diversity in glacial snow was lower than that in glacial soil. Principal coordinate analysis (PCoA) and heatmap analysis indicated that there were major differences in bacterial communities between glacial snow and glacial soil. Most bacteria were different between the two habitats; however, there were some common bacteria shared between glacial snow and glacial soil. Some rare or functional bacterial resources were also present in the Chongce Ice Cap. These findings provide a preliminary understanding of the shifts in bacterial diversity and communities from glacial snow to glacial soil after the melting and inflow of glacial snow into glacial soil.

  9. Valley evolution of the Lower Rhine in LGM, Lateglacial and Early Holocene.

    NARCIS (Netherlands)

    Cohen, K.M.; Hoek, W.Z.; Stouthamer, E.; Geurts, A.H.; Janssens, M.; Kasse, C.; Busschers, F.S.; Hijma, M.P.; Erkens, G.

    2013-01-01

    The impact of transient climate change, for example at glacial-interglacial transitions, on the alluvial valley of the lower reaches of larger river systems has become a classic topic of fluvial geomorphology and quaternary geological study. The process of contraction of Holocene river activity into

  10. Molecular identification of Armillaria gallica from the Niobrara Valley Preserve in Nebraska

    Science.gov (United States)

    Mee-Sook Kim; Ned B. Klopfenstein

    2011-01-01

    Armillaria isolates were collected from a unique forest ecosystem in the Niobrara Valley Preserve in Nebraska, USA, which comprises a glacial and early postglacial refugium in the central plains of North America. The isolates were collected from diverse forest trees representing a unique mixture of forest types. Combined methods of rDNA sequencing and flow cytometric...

  11. The dispersion of fibrous amphiboles by glacial processes in the area surrounding Libby, Montana, USA

    Science.gov (United States)

    Langer, William H.; Van Gosen, Bradley S.; Meeker, Gregory P.; Adams, David T.; Hoefen, Todd M.

    2011-01-01

    Mining operations began at a world-class vermiculite deposit at Vermiculite Mountain near Libby, Montana, circa 1920 and ended in 1990. Fibrous and asbestiform amphiboles intergrown with vermiculite ore are suspected to be a causative factor in an abnormally high number of cases of respiratory diseases in former mine and mill workers, and in residents of Libby. The question addressed in this report is whether some of the amphibole from Vermiculite Mountain could have been dispersed by Pleistocene glacial processes rather than by human activity after vermiculite mining began. The history of Pinedale glaciation in the Libby area provides a framework for estimating the presence and distribution of asbestiform amphiboles derived from Vermiculite Mountain and found in naturally occurring sediments of Glacial Lake Kootenai that underlie the Libby Valley area. There were two situations where sediments derived from Vermiculite Mountain were deposited into Glacial Lake Kootenai: (1) as lake-bottom sediments derived from meltwater flowing down Rainy Creek when the valley south of Vermiculite Mountain was free of ice but active ice still covered Vermiculite Mountain; and (2) as lake-bottom sediments eroded from the Rainy Creek outwash and re-deposited during a re-advance of the Purcell Trench Glacier lobe near Moyie Springs, Idaho.

  12. Obsidian hydration dates glacial loading?

    Science.gov (United States)

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

  13. Timing of maximum glacial extent and deglaciation from HualcaHualca volcano (southern Peru), obtained with cosmogenic 36Cl.

    Science.gov (United States)

    Alcalá, Jesus; Palacios, David; Vazquez, Lorenzo; Juan Zamorano, Jose

    2015-04-01

    Andean glacial deposits are key records of climate fluctuations in the southern hemisphere. During the last decades, in situ cosmogenic nuclides have provided fresh and significant dates to determine past glacier behavior in this region. But still there are many important discrepancies such as the impact of Last Glacial Maximum or the influence of Late Glacial climatic events on glacial mass balances. Furthermore, glacial chronologies from many sites are still missing, such as HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a high volcano of the Peruvian Andes located 70 km northwest of Arequipa. The goal of this study is to establish the age of the Maximum Glacier Extent (MGE) and deglaciation at HualcaHualca volcano. To achieve this objetive, we focused in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) characterized by a well-preserved sequence of moraines and roches moutonnées. The method is based on geomorphological analysis supported by cosmogenic 36Cl surface exposure dating. 36Cl ages have been estimated with the CHLOE calculator and were compared with other central Andean glacial chronologies as well as paleoclimatological proxies. In Huayuray valley, exposure ages indicates that MGE occurred ~ 18 - 16 ka. Later, the ice mass gradually retreated but this process was interrupted by at least two readvances; the last one has been dated at ~ 12 ka. In the other hand, 36Cl result reflects a MGE age of ~ 13 ka in Mollebaya valley. Also, two samples obtained in Pujro-Huayjo and Mucurca valleys associated with MGE have an exposure age of 10-9 ka, but likely are moraine boulders affected by exhumation or erosion processes. Deglaciation in HualcaHualca volcano began abruptly ~ 11.5 ka ago according to a 36Cl age from a polished and striated bedrock in Pujro Huayjo valley, presumably as a result of reduced precipitation as well as a global increase of temperatures. The glacier evolution at HualcaHualca volcano presents a high correlation with

  14. Holocene glacial fluctuations in southern South America

    Science.gov (United States)

    Reynhout, S.; Sagredo, E. A.; Kaplan, M. R.; Aravena, J. C.; Martini, M. A.; Strelin, J. A.; Schaefer, J. M.

    2016-12-01

    Understanding the timing and magnitude of former glacier fluctuations is critical to decipher long-term climatic trends and to unravel both natural cycles and human impact on the current glacial behavior. Despite more than seven decades of research efforts, a unifying model of Holocene glacial fluctuations in Southern South America remains elusive. Here, we present the state-of-the-art regarding the timing of Holocene glacial fluctuation in southern Patagonia-Tierra del Fuego, with a focus on a new generation of high-resolution radiocarbon and 10Be surface exposure dating chronologies. Recently acquired evidence suggest that after receding from advanced Late Glacial positions, Patagonian glaciers were for the most part close to, or even behind, present ice margins during the Early Holocene. On the other hand, emerging chronologies indicate that in some areas there were extensive expansions (century scale?) that punctuated the warm interval. Subsequently, we have evidence of multiple millennial timescale glacial advances starting in the middle Holocene. Several glacial maxima are defined by moraines and other landforms from 7000 years ago to the 19th century, with a gap sometime between 4,500 and 2,500 years ago. The last set of advances began around 800-600 years ago. Although glacial activity is documented in Patagonia at the same time as the European Little Ice Age, the extent of these glacial events are less prominent than those of the mid-Holocene. The causes that may explain these glacial fluctuations remain elusive. Finally, we discuss ongoing efforts to better define the timing and extent of Holocene glaciations in southern South America, and to establish the basis to test competing hypothesis of regional Holocene climate variability.

  15. Glacial evolution of the Ampato Volcanic Complex (Peru)

    Science.gov (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.; Vázquez, L.

    2009-04-01

    then digitized in a Geographical Information System (GIS) using the existing 1:100,000 maps (National Geographical Institute of Peru) as a topographical base. Once the geomorphological maps had been analyzed, we decided to focus on the glacial evolution of a representative section of the Ampato Complex, specifically the Huayuray valley, located north of the HualcaHualca volcano. According to the altitudinal position and the degree of conservation of the moraines along the Quebrada, glacial phases of the Last Glacial Maximum (LGM), the Neoglacial and the Little Ice Age (LIA) were identified. The GIS was then used to delimit and calculate the ice surface area of each one. The same was also done for the years 1955 and 2000 AD, based on the interpretation of aerial photographs and satellite images from those years. Next, the ELA was calculated using the Altitude Area (AA) method (Osmaston, 2005) using GIS and the glacier paleotopography was reconstructed using geomorphological evidence (Carr, S & Coleman, C, 2007). To obtain numerical ages of moraine boulders and glacially abraded bedrock we applied cosmogenic36Cl surface exposure dating (Gosse & Phillips, 2001), which is the best method for volcanic rocks with no quartz content. Samples were collected from stable boulders located at the crests of moraine ridges and over 1 m in height. They were analyzed following procedures by Zreda et al. (1999) and Phillips (2003); physical analyses were undertaken at Universidad Complutense in Spain and physic-chemical analyses at the PRIME laboratory (Purdue University). LGM moraine forms always occupy the lowest altitude position, forming well-defined moraine arcs and ridges, with large dimensions and well preserved. During this phase, the climate was colder and damper than is currently the case in the Central Andes. Calculations show mean temperature during this period to have been 4 - 6°C below present values, and with more abundant precipitation (Seltzer et al., 2002). Under

  16. Cryostratigraphy and sedimentology of high-Arctic fjord-valleys

    OpenAIRE

    Gilbert, Graham Lewis

    2018-01-01

    Fjord-valleys, as sediment-filled palaeofjords, are characteristic of formerly glaciated mountainous coastal areas. High-Arctic fjord-valleys commonly host permafrost, but are poorly accessible and hence have drawn relatively little research. The research presented in this thesis combines the methods of cryostratigraphy, clastic sedimentology, sequence stratigraphy, geomorphology and geochronology to investigate the sedimentary infilling, permafrost formation and late Quaternary landscape dev...

  17. Correlating Ice Cores from Quelccaya Ice Cap with Chronology from Little Ice Age Glacial Extents

    Science.gov (United States)

    Stroup, J. S.; Kelly, M. A.; Lowell, T. V.

    2010-12-01

    Proxy records indicate Southern Hemisphere climatic changes during the Little Ice Age (LIA; ~1300-1850 AD). In particular, records of change in and around the tropical latitudes require attention because these areas are sensitive to climatic change and record the dynamic interplay between hemispheres (Oerlemans, 2005). Despite this significance, relatively few records exist for the southern tropics. Here we present a reconstruction of glacial fluctuations of Quelccaya Ice Cap (QIC), Peruvian Andes, from pre-LIA up to the present day. In the Qori Kalis valley, extensive sets of moraines exist beginning with the 1963 AD ice margin (Thompson et al., 2006) and getting progressively older down valley. Several of these older moraines can be traced and are continuous with moraines in the Challpa Cocha valley. These moraines have been dated at chronology of past ice cap extents are correlated with ice core records from QIC which show an accumulation increase during ~1500-1700 AD and an accumulation decrease during ~1720-1860 AD (Thompson et al., 1985; 1986; 2006). In addition, other proxy records from Peru and the tropics are correlated with the records at QIC as a means to understand climate conditions during the LIA. This work forms the basis for future modeling of the glacial system during the LIA at QIC and for modeling of past temperature and precipitation regimes at high altitude in the tropics.

  18. Glacial-interglacial atmospheric CO2 change: a possible

    Directory of Open Access Journals (Sweden)

    L. C. Skinner

    2009-09-01

    Full Text Available So far, the exploration of possible mechanisms for glacial atmospheric CO2 drawdown and marine carbon sequestration has tended to focus on dynamic or kinetic processes (i.e. variable mixing-, equilibration- or export rates. Here an attempt is made to underline instead the possible importance of changes in the standing volumes of intra-oceanic carbon reservoirs (i.e. different water-masses in influencing the total marine carbon inventory. By way of illustration, a simple mechanism is proposed for enhancing the marine carbon inventory via an increase in the volume of relatively cold and carbon-enriched deep water, analogous to modern Lower Circumpolar Deep Water (LCDW, filling the ocean basins. A set of simple box-model experiments confirm the expectation that a deep sea dominated by an expanded LCDW-like watermass holds more CO2, without any pre-imposed changes in ocean overturning rate, biological export or ocean-atmosphere exchange. The magnitude of this "standing volume effect" (which operates by boosting the solubility- and biological pumps might be as large as the contributions that have previously been attributed to carbonate compensation, terrestrial biosphere reduction or ocean fertilisation for example. By providing a means of not only enhancing but also driving changes in the efficiency of the biological- and solubility pumps, this standing volume mechanism may help to reduce the amount of glacial-interglacial CO2 change that remains to be explained by other mechanisms that are difficult to assess in the geological archive, such as reduced mass transport or mixing rates in particular. This in turn could help narrow the search for forcing conditions capable of pushing the global carbon cycle between glacial and interglacial modes.

  19. Ground water in Dale Valley, New York

    Science.gov (United States)

    Randall, Allan D.

    1979-01-01

    Dale Valley is a broad valley segment, enlarged by glacial erosion, at the headwaters of Little Tonawanda Creek near Warsaw , New York. A thin, shallow alluvial aquifer immediately underlies the valley floor but is little used. A deeper gravel aquifer, buried beneath many feet of lake deposits, is tapped by several industrial wells. A finite-difference digital model treated the deep aquifer as two-dimensional with recharge and discharge through a confining layer. It was calibrated by simulating (1) natural conditions, (2) an 18-day aquifer test, and (3) 91 days of well-field operation. Streamflow records and model simulations suggest that in moderately wet years such as 1974, a demand of 750 gallons per minute could be met by withdrawal from the creek and from the aquifer without excessive drawdown at production wells or existing domestic wells. With reasonable but unverified model adjustments to simulate an unusually dry year, the model predicts that a demand of 600 gallons per minute could be met from the same sources. Water high in chloride has migrated from bedrock into parts of the deep aquifer. Industrial pumpage, faults in the bedrock, and the natural flow system may be responsible. (Woodard-USGS)

  20. AN GEOLOGICAL OVERVIEW OF GLACIAL ACCUMULATION AND EROSIONAL OCCURRENCES AT THE VELEBIT AND THE BIOKOVO MTS., CROATIA

    Directory of Open Access Journals (Sweden)

    Josipa Velić

    2017-01-01

    Full Text Available Numerous accumulation and erosional forms originating from the activity of small valley glaciers or cirque glaciers occur in the highest mountains in Croatia: Velebit (1757 m and Biokovo (1762 m. They were produced during the Upper Pleistocene, in the Würm glacial stage of the Alpine classification. Accumulation forms comprise ground, terminal and recessional moraines, drumlins, eskers, glacial erratics and glaciofluvial and glaciolacustrine sediments. Single ridge eskers are often associated with areas of kame and kettle topography. Among erosional occurrences roche moutonnée (sheepback rocks, U-shaped valleys ranging in size from meso-macro, arêtes, hanging valleys, meso-sized cirques, kettles, and striations were noted. In Croatian Dinarides such forms in most cases occur between 900 and 1400 meters altitude. During the early to middle Würm glacial maximum, the snow line was above 900 m, perhaps even above 1000 m altitude, and sea levels were 120 meters lower than at present day. Considering the features of the present relief, ice cover was probably 200 to 300 m thick. Features of drumlins, eskers and kettles point to warm-based glaciers. The drumlins are small – up to 100 meters long and 50 meters wide, with the most common long axis ranging orientation from 130o – 310o. The near total absence of platy clasts, as well as their stratigraphic affiliation, largely reflects features of source rocks.

  1. The Downstream Fate of Glacial Runoff and Groundwater in the Cordillera Blanca, Peru

    Science.gov (United States)

    McKenzie, J. M.; Gordon, R.; Chavez, D.; Maharaj, L.; Baraer, M.; Mark, B. G.; Lautz, L. K.

    2013-12-01

    Rapid glacier recession in the Cordillera Blanca, Peru, is raising concerns about current and future water resources for the inhabitants of the Rio Santa watershed. Glacier meltwater buffers stream discharge throughout the range, reducing the variability of annual runoff and maintaining stream flows during the dry season. Groundwater is also an important component of dry season runoff as it can contribute as much as 50-70% to outflow in some Rio Santa tributaries. A better understanding of groundwater dynamics in high elevation watersheds is needed, including quantification of recharge, subsurface processes, and available storage. We present the results from recent groundwater studies in the Cordillera Blanca where numerous investigative techniques have been used, including ground penetrating radar, hydraulic conductivity measurements, tracer tests, and hydrochemical mixing models. Our research focuses primarily on the low-relief pampa valley floors across which glacial-melt derived rivers flow. Across the Cordillera, these valley systems cover approximately 65 km2 and are comprised of unconsolidated glacial, talus, and lacustrine deposits and wetlands. The valleys commonly have buried, permeable, talus aquifers that are overlain by relatively impermeable, glaciolacustrine deposits. Glaciofluvial outwash deposits also act as aquifers (hydraulic conductivity of 10-4 m/s). The travel time of water stored in these systems is generally less than 3-4 years and the maximum observed dry season groundwater velocity is 60 cm/day. While groundwater represents an important component of dry season water resources source of water in the Cordillera Blanca, it is also potentially vulnerable to climate change including changes in the precipitation regime and decrease in glacially derived recharge.

  2. The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica

    International Nuclear Information System (INIS)

    Lyons, W.B.; Leslie, D.L.; Harmon, R.S.; Neumann, K.; Welch, K.A.; Bisson, K.M.; McKnight, D.M.

    2013-01-01

    Highlights: ► δ 13 C-DIC reported from McMurdo Dry Valleys, Antarctica, streams. ► Stream water δ 13 C PDB values range −9.4‰ to +5.1‰, largely inorganic in character. ► Atmospheric exchange is the dominant control on δ 13 C-DIC. - Abstract: The McMurdo Dry Valleys region of Antarctica is the largest ice-free region on the continent. This study reports the first C stable isotope measurements for dissolved inorganic C present in ephemeral streams in four dry valleys that flow for four to twelve weeks during the austral summer. One of these valleys, Taylor Valley, has been the focus of the McMurdo Dry Valleys Long-Term Ecological Research (MCM-LTER) program since 1993. Within Taylor Valley, numerous ephemeral streams deliver water to three perennially ice-covered, closed-basin lakes: Lake Fryxell, Lake Hoare, and Lake Bonney. The Onyx River in the Wright Valley, the longest river in Antarctica, flows for 40 km from the Wright Lower Glacier and Lake Brownworth at the foot of the glacier to Lake Vanda. Streamflow in the McMurdo Dry Valley streams is produced primarily from glacial melt, as there is no overland flow. However, hyporheic zone exchange can be a major hydrogeochemical process in these streams. Depending on landscape position, these streams vary in gradient, channel substrate, biomass abundance, and hyporheic zone extent. This study sampled streams from Taylor, Wright, Garwood, and Miers Valleys and conducted diurnal sampling of two streams of different character in Taylor Valley. In addition, transect sampling was undertaken of the Onyx River in Wright Valley. The δ 13 C PDB values from these streams span a range of greater than 14‰, from −9.4‰ to +5.1‰, with the majority of samples falling between −3‰ and +2‰, suggesting that the C stable isotope composition of dissolved C in McMurdo Dry Valley streams is largely inorganic in character. Because there are no vascular plants on this landscape and no groundwater input to these

  3. Geologic features of the Connecticut Valley, Massachusetts, as related to recent floods

    Science.gov (United States)

    Jahns, Richard Henry

    1947-01-01

    gorge is due to a filling by glacial debris, notably by sediments deposited in late glacial lakes. Following disappearance of the last ice sheet and draining of the associated, lakes, the Connecticut River resumed existence and began a new chapter in its history. In those areas where the river regained its preglacial course, it now flows on sediments considerably above the rock floor of the old gorge. Where the gorge was narrow and deep, the upper parts of its walls have confined the postglacial river within rather narrow limits, as in the northern part of the state. Where it was sufficiently wide to be filled by glacial sediments over large areas, the postglacial river has meandered broadly, as in the area north of the Holyoke-Mount Tom Range. In two areas in Massachusetts and in one immediately south in Connecticut, however, the river was forced from its preglacial gorge, and its new channel has been superimposed on bedrock, with development of rapids and falls. Each of these postglacial rock channels acts as a spillway whose level controls the local base level of the river as far upstream as the next spillway. These spillways are not to be confused with other, more spectacular gorges, which are of preglacial origin and in which the present river does not flow on bedrock. The Recent Connecticut has formed extensive flood plains and terraces through repeated sequences of erosion by lateral corrosion and downward scour, followed by deposition of .silt and sand veneers. These features, although irregular in detail, appear to be assignable to five general levels, whose means are approximately 49, 37, 30, 18, and 10 feet above present mean river level. In addition, an 80-foot terrace in the northern part of the valley was left perched, in its present position when the Connecticut abandoned its course over. a rock barrier near Turners Falls in favor of an adjacent much lower gap. The normal terraces and flood plains, slope very gently away from their riverw

  4. Filling a Conical Cavity

    Science.gov (United States)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  5. Valley polarization in bismuth

    Science.gov (United States)

    Fauque, Benoit

    2013-03-01

    The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

  6. Glacial vs. Interglacial Period Contrasts in Midlatitude Fluvial Systems, with Examples from Western Europe and the Texas Coastal Plain

    Science.gov (United States)

    Blum, M.

    2001-12-01

    Mixed bedrock-alluvial valleys are the conveyor belts for sediment delivery to passive continental margins. Mapping, stratigraphic and sedimentologic investigations, and development of geochronological frameworks for large midlatitude rivers of this type, in Western Europe and the Texas Coastal Plain, provide for evaluation of fluvial responses to climate change over the last glacial-interglacial period, and the foundations for future quantitative evaluation of long profile evolution, changes through time in flood magnitude, and changes in storage and flux of sediments. This paper focuses on two issues. First, glacial vs. interglacial period fluvial systems are fundamentally different in terms of channel geometry, depositional style, and patterns of sediment storage. Glacial-period systems were dominated by coarse-grained channel belts (braided channels in Europe, large-wavelength meandering in Texas), and lacked fine-grained flood-plain deposits, whereas Holocene units, especially those of late Holocene age, contain appreciable thicknesses of flood-plain facies. Hence, extreme overbank flooding was not significant during the long glacial period, most flood events were contained within bankfull channel perimeters, and fine sediments were bypassed through the system to marine basins. By contrast, extreme overbank floods have been increasingly important during the relatively short Holocene, and a significant volume of fine sediment is sequestered in flood-plain settings. Second, glacial vs. interglacial systems exhibit different amplitudes and frequencies of fluvial adjustment to climate change. High-amplitude but low-frequency adjustments characterized the long glacial period, with 2-3 extended periods of lateral migration and sediment storage puncuated by episodes of valley incision. Low-amplitude but high-frequency adjustments have been more typical of the short Holocene, when there has been little net valley incision or net changes in sediment storage, but

  7. Causes of strong ocean heating during glacial periods

    Science.gov (United States)

    Zimov, N.; Zimov, S. A.

    2013-12-01

    During the last deglaciation period, the strongest climate changes occurred across the North Atlantic regions. Analyses of borehole temperatures from the Greenland ice sheet have yielded air temperature change estimates of 25°C over the deglaciation period (Dahl-Jensen et al. 1998). Such huge temperature changes cannot currently be explained in the frames of modern knowledge about climate. We propose that glacial-interglacial cycles are connected with gradual warming of ocean interior waters over the course of glaciations and quick transport of accumulated heat from ocean to the atmosphere during the deglaciation periods. Modern day ocean circulation is dominated by thermal convection with cold waters subsiding in the Northern Atlantic and filling up the ocean interior with cold and heavy water. However during the glaciation thermal circulation stopped and ocean circulation was driven by 'haline pumps' -Red and Mediterranean seas connected with ocean with only narrow but deep straights acts as evaporative basins, separating ocean water into fresh water which returns to the ocean surface (precipitation) and warm but salty, and therefore heavy, water which flows down to the ocean floor. This haline pump is stratifying the ocean, allowing warmer water locate under the colder water and thus stopping thermal convection in the ocean. Additional ocean interior warming is driven by geothermal heat flux and decomposition of organic rain. To test the hypothesis we present simple ocean box model that describes thermohaline circulation in the World Ocean. The first box is the Red and Mediterranean sea, the second is united high-latitude seas, the third is the ocean surface, and the fourth the ocean interior. The volume of these water masses and straight cross-sections are taken to be close to real values. We have accepted that the exchange of water between boxes is proportional to the difference in water density in these boxes, Sun energy inputs to the ocean and sea surface

  8. Mammoths inside the Alps during the last glacial period: Radiocarbon constraints from Austria and palaeoenvironmental implications

    Science.gov (United States)

    Spötl, Christoph; Reimer, Paula J.; Göhlich, Ursula B.

    2018-06-01

    This study examines remains of the woolly mammoth (Mammuthus primigenius) found inside the Austrian Alps, an area occupied by an extensive ice-stream network during the Last Glacial Maximum. The data demonstrate that these cold steppe-adapted animals locally migrated several tens of kilometers into alpine valleys. Radiocarbon analyses constrain the age of these fossils to the first half of Marine Isotope Stage 3, documenting ice-free conditions in major valleys at that time. We also provide a list of all traceable Austrian sites of Mammuthus primigenius, totaling about 230 localities, compiled through 15 museums and collections in Austria. The vast majority of these findings are from the corridors of the Danube and Mur rivers and their tributaries and the adjacent loess-covered foreland of the Alps, areas that were never ice-covered during Pleistocene glaciations.

  9. Lake-level increasing under the climate cryoaridization conditions during the Last Glacial Maximum

    Science.gov (United States)

    Amosov, Mikhail; Strelkov, Ivan

    2017-04-01

    A lake genesis and lake-level increasing during the Last Glacial Maximum (LGM) are the paramount issues in paleoclimatology. Investigating these problems reveals the regularities of lake development and figures out an arid territory conditions at the LGM stage. Pluvial theory is the most prevalent conception of lake formation during the LGM. This theory is based on a fact that the water bodies emerged and their level increased due to torrential rainfalls. In this study, it is paid attention to an alternative assumption of lake genesis at the LGM stage, which is called climate cryoaridization. In accordance with this hypothesis, the endorheic water basins had their level enlarged because of a simultaneous climate aridity and temperature decrease. In this research, a lake-level increasing in endorheic regions of Central Asia and South American Altiplano of the Andes is described. The lake investigation is related to its conditions during the LGM. The study also includes a lake catalogue clearly presenting the basin conditions at the LGM stage and nowadays. The data compilation partly consists of information from an earlier work of Mikhail Amosov, Lake-levels, Vegetation And Climate In Central Asia During The Last Glacial Maximum (EGU2014-3015). According to the investigation, a lake catalogue on 27 lakes showed that most of the water bodies had higher level. This feature could be mentioned for the biggest lakes of the Aral Sea, Lake Balkhash, Issyk-Kul etc. and for the small ones located in the mountains, such as Pamir, Tian-Shan and Tibet. Yet some lakes that are situated in Central Asian periphery (Lake Qinghai and lakes in Inner Mongolia) used to be lower than nowadays. Also, the lake-level increasing of Altiplano turned to be a significant feature during the LGM in accordance with the data of 5 lakes, such as Titicaca, Coipasa-Uyuni, Lejia, Miscanti and Santa-Maria. Most of the current endorheic basins at the LGM stage were filled with water due to abundant

  10. Greening Turner Valley

    International Nuclear Information System (INIS)

    Byfield, M.

    2010-01-01

    This article discussed remedial activities undertaken in the Turner Valley. Remedial action in the valley must satisfy the financial concerns of engineers and investors as well as the environmental concerns of residents and regulators. Natural gas production in the Turner Valley began in 1914. The production practices were harmful and wasteful. Soil and water pollution was not considered a problem until recently. The impacts of cumulative effects and other pollution hazards are now being considered as part of many oil and gas environmental management programs. Companies know it is cheaper and safer to prevent pollutants from being released, and more efficient to clean them up quickly. Oil and gas companies are also committed to remediating historical problems. Several factors have simplified remediation plans in the Turner Valley. Area real estate values are now among the highest in Alberta. While the valley residents are generally friendly to the petroleum industry, strong communication with all stakeholders in the region is needed. 1 fig.

  11. Water resources of Parowan Valley, Iron County, Utah

    Science.gov (United States)

    Marston, Thomas M.

    2017-08-29

    Parowan Valley, in Iron County, Utah, covers about 160 square miles west of the Red Cliffs and includes the towns of Parowan, Paragonah, and Summit. The valley is a structural depression formed by northwest-trending faults and is, essentially, a closed surface-water basin although a small part of the valley at the southwestern end drains into the adjacent Cedar Valley. Groundwater occurs in and has been developed mainly from the unconsolidated basin-fill aquifer. Long-term downward trends in groundwater levels have been documented by the U.S. Geological Survey (USGS) since the mid-1950s. The water resources of Parowan Valley were assessed during 2012 to 2014 with an emphasis on refining the understanding of the groundwater and surface-water systems and updating the groundwater budget.Surface-water discharge of five perennial mountain streams that enter Parowan Valley was measured from 2013 to 2014. The total annual surface-water discharge of the five streams during 2013 to 2014 was about 18,000 acre-feet (acre-ft) compared to the average annual streamflow of about 22,000 acre-ft from USGS streamgages operated on the three largest of these streams from the 1940s to the 1980s. The largest stream, Parowan Creek, contributes more than 50 percent of the annual surface-water discharge to the valley, with smaller amounts contributed by Red, Summit, Little, and Cottonwood Creeks.Average annual recharge to the Parowan Valley groundwater system was estimated to be about 25,000 acre-ft from 1994 to 2013. Nearly all recharge occurs as direct infiltration of snowmelt and rainfall on the Markagunt Plateau east of the valley. Smaller amounts of recharge occur as infiltration of streamflow and unconsumed irrigation water near the east side of the valley on alluvial fans associated with mountain streams at the foot of the Red Cliffs. Subsurface flow from the mountain block to the east of the valley is a significant source of groundwater recharge to the basin-fill aquifer

  12. Last Glacial Maximum Salinity Reconstruction

    Science.gov (United States)

    Homola, K.; Spivack, A. J.

    2016-12-01

    It has been previously demonstrated that salinity can be reconstructed from sediment porewater. The goal of our study is to reconstruct high precision salinity during the Last Glacial Maximum (LGM). Salinity is usually determined at high precision via conductivity, which requires a larger volume of water than can be extracted from a sediment core, or via chloride titration, which yields lower than ideal precision. It has been demonstrated for water column samples that high precision density measurements can be used to determine salinity at the precision of a conductivity measurement using the equation of state of seawater. However, water column seawater has a relatively constant composition, in contrast to porewater, where variations from standard seawater composition occur. These deviations, which affect the equation of state, must be corrected for through precise measurements of each ion's concentration and knowledge of apparent partial molar density in seawater. We have developed a density-based method for determining porewater salinity that requires only 5 mL of sample, achieving density precisions of 10-6 g/mL. We have applied this method to porewater samples extracted from long cores collected along a N-S transect across the western North Atlantic (R/V Knorr cruise KN223). Density was determined to a precision of 2.3x10-6 g/mL, which translates to salinity uncertainty of 0.002 gms/kg if the effect of differences in composition is well constrained. Concentrations of anions (Cl-, and SO4-2) and cations (Na+, Mg+, Ca+2, and K+) were measured. To correct salinities at the precision required to unravel LGM Meridional Overturning Circulation, our ion precisions must be better than 0.1% for SO4-/Cl- and Mg+/Na+, and 0.4% for Ca+/Na+, and K+/Na+. Alkalinity, pH and Dissolved Inorganic Carbon of the porewater were determined to precisions better than 4% when ratioed to Cl-, and used to calculate HCO3-, and CO3-2. Apparent partial molar densities in seawater were

  13. Tension-filled Governance?

    DEFF Research Database (Denmark)

    Celik, Tim Holst

    on the statesituated tension-filled functional relationship between legitimation and accumulation, the study both historically and theoretically reworks this approach and reapplies it for the post-1970s/1990s governance period. It asks whether and to what extent governance has served as a distinctive post- 1970s/1990s...

  14. filled neutron detectors

    Indian Academy of Sciences (India)

    Boron trifluoride (BF3) proportional counters are used as detectors for thermal neutrons. They are characterized by high neutron sensitivity and good gamma discriminating properties. Most practical BF3 counters are filled with pure boron trifluoride gas enriched up to 96% 10B. But BF3 is not an ideal proportional counter ...

  15. Gas filled detectors

    International Nuclear Information System (INIS)

    Stephan, C.

    1993-01-01

    The main types of gas filled nuclear detectors: ionization chambers, proportional counters, parallel-plate avalanche counters (PPAC) and microstrip detectors are described. New devices are shown. A description of the processes involved in such detectors is also given. (K.A.) 123 refs.; 25 figs.; 3 tabs

  16. Phylogeographic insights into cryptic glacial refugia.

    Science.gov (United States)

    Provan, Jim; Bennett, K D

    2008-10-01

    The glacial episodes of the Quaternary (2.6 million years ago-present) were a major factor in shaping the present-day distributions of extant flora and fauna, with expansions and contractions of the ice sheets rendering large areas uninhabitable for most species. Fossil records suggest that many species survived glacial maxima by retreating to refugia, usually at lower latitudes. Recently, phylogeographic studies have given support to the existence of previously unknown, or cryptic, refugia. Here we summarise many of these insights into the glacial histories of species in cryptic refugia gained through phylogeographic approaches. Understanding such refugia might be important as the Earth heads into another period of climate change, in terms of predicting the effects on species distribution and survival.

  17. The glacial cycles and cosmic rays

    CERN Document Server

    Kirkby, Jasper; Müller, R A

    2004-01-01

    The cause of the glacial cycles remains a mystery. The origin is widely accepted to be astronomical since paleoclimatic archives contain strong spectral components that match the frequencies of Earth's orbital modulation. Milankovitch insolation theory contains similar frequencies and has become established as the standard model of the glacial cycles. However, high precision paleoclimatic data have revealed serious discrepancies with the Milankovitch model that fundamentally challenge its validity and re-open the question of what causes the glacial cycles. We propose here that the ice ages are initially driven not by insolation cycles but by cosmic ray changes, probably through their effect on clouds. This conclusion is based on a wide range of evidence, including results presented here on speleothem growth in caves in Austria and Oman, and on a record of cosmic ray flux over the past 220 kyr obtained from the 10Be composition of deep-ocean sediments.

  18. Infilling and flooding of the Mekong River incised valley during deglacial sea-level rise

    Science.gov (United States)

    Tjallingii, Rik; Stattegger, Karl; Wetzel, Andreas; Van Phach, Phung

    2010-06-01

    The abrupt transition from fluvial to marine deposition of incised-valley-fill sediments retrieved from the southeast Vietnamese shelf, accurately records the postglacial transgression after 14 ka before present (BP). Valley-filling sediments consist of fluvial mud, whereas sedimentation after the transgression is characterized by shallow-marine carbonate sands. This change in sediment composition is accurately marked in high-resolution X-ray fluorescence (XRF) core scanning records. Rapid aggradation of fluvial sediments at the river mouth nearly completely filled the Mekong incised valley prior to flooding. However, accumulation rates strongly reduced in the valley after the river-mouth system flooded and stepped back. This also affected the sediment supply to deeper parts of the southeast Vietnamese shelf. Comparison of the Mekong valley-filling with the East Asian sea-level history of sub- and inter-tidal sediment records shows that the transgressive surface preserved in the incised-valley-fill records is a robust sea-level indicator. The valley was nearly completely filled with fluvial sediments between 13.0 and 9.5 ka BP when sea-level rose rather constantly with approximately 10 mm/yr, as indicated by the East Asian sea-level record. At shallower parts of the shelf, significant sediment reworking and the establishment of estuarine conditions at the final stage of infilling complicates accurate dating of the transgressive surface. Nevertheless, incised-valley-fill records and land-based drill sites indicate a vast and rapid flooding of the shelf from the location of the modern Vietnamese coastline to the Cambodian lowlands between 9.5 ka and 8.5 ka BP. Fast flooding of this part of the shelf is related with the low shelf gradient and a strong acceleration of the East Asian sea-level rise from 34 to 9 meter below modern sea level (mbsl) corresponding to the sea-level jump of melt water pulse (MWP) 1C.

  19. Glacial conditions in the Red Sea

    Science.gov (United States)

    Rohling, Eelco J.

    1994-10-01

    In this paper, results from previous studies on planktonic foraminifera, δ18O, and global sea level are combined to discuss climatic conditions in the Red Sea during the last glacial maximum (18,000 B.P.). First, the influence of 120-m sea level lowering on the exchange transport through the strait of Bab-el-Mandab is considered. This strait is the only natural connection of the Red Sea to the open ocean. Next, glacial Red Sea outflow salinity is estimated (about 48 parts per thousand) from the foraminiferal record. Combined, these results yield an estimate of the glacial net water deficit, which appears to have been quite similar to the present (about 2 m yr-1). Finally, budget calculation of δ18O fluxes suggests that the glacial δ18O value of evaporation was about 50% of the present value. This is considered to have resulted from substantially increased mean wind speeds over the glacial Red Sea, which would have caused a rapid drop in the kinematic fractionation factor for 18O. The sensitivity of the calculated values for water deficit and isotopic fractionation to the various assumptions and estimates is evaluated in the discussion. Improvents are to be expected especially through research on the glacial salinity contrast between the Red Sea and Gulf of Aden. It is argued, however, that such future improvement will likely result in a worsening of the isotopic discrepancy, thus increasing the need for an additional mechanism that influenced fractionation (such as mean wind speed). This study demonstrates the need for caution when calculating paleosalinities from δ18O records under the assumption that the modern S∶δ18O relation has remained constant through time. Previously overlooked factors, such as mean wind speed, may have significantly altered that relation in the past.

  20. A luminescence dating study of the sediment stratigraphy of the Lajia Ruins in the upper Yellow River valley, China

    Science.gov (United States)

    Zhang, Yuzhu; Huang, Chun Chang; Pang, Jiangli; Zhou, Yali; Zha, Xiaochun; Wang, Longsheng; Zhou, Liang; Guo, Yongqiang; Wang, Leibin

    2014-06-01

    Pedo-sedimentological fieldwork were carried out in the Lajia Ruins within the Guanting Basin along the upper Yellow River valley. In the eolian loess-soil sections on the second river terrace in the Lajia Ruins, we find that the land of the Qijia Culture (4.20-3.95 ka BP) are fractured by several sets of earthquake fissures. A conglomerated red clay covers the ground of the Qijia Culture and also fills in the earthquake fissures. The clay was deposited by enormous mudflows in association with catastrophic earthquakes and rainstorms. The aim of this study is to provide a luminescence chronology of the sediment stratigraphy of the Lajia Ruins. Eight samples were taken from an eolian loess-soil section (Xialajia section) in the ruins for optically stimulated luminescence (OSL) dating. The OSL ages are in stratigraphic order and range from (31.94 ± 1.99) ka to (0.76 ± 0.02) ka. Combined OSL and 14C ages with additional stratigraphic correlations, a chronological framework is established. We conclude that: (1) the second terrace of the upper part of Yellow River formed 35.00 ka ago, which was followed by the accumulation of the eolian loess-soil section; and (2) the eolian loess-soil section is composed of the Malan Loess of the late last glacial (MIS-2) and Holocene loess-soil sequences.

  1. Topographic evolution of Yosemite Valley from Low Temperature Thermochronology

    Science.gov (United States)

    Tripathy-Lang, A.; Shuster, D. L.; Cuffey, K. M.; Fox, M.

    2014-12-01

    In this contribution, we interrogate the timing of km-scale topography development in the region around Yosemite Valley, California. Our goal is to determine when this spectacular glacial valley was carved, and how this might help address controversy surrounding the topographic evolution of the Sierra Nevada. At the scale of the range, two rival hypotheses are each supported by different datasets. Low-temperature thermochronology supports the idea that the range has been high-standing since the Cretaceous, whereas geomorphic evidence suggests that much of the elevation of the Sierra Nevada was attained during the Pliocene. Recent work by McPhillips and Brandon (2012) suggests instead that both ideas are valid, with the range losing much elevation during the Cenozoic, but regaining it during Miocene surface uplift.At the local scale, the classic study of Matthes (1930) determined that most of Yosemite Valley was excavated by the Sherwin-age glaciation that ended ~1 Ma. The consensus view is in agreement, although some argue that nearby comparable valleys comparable were carved long ago (e.g., House et al., 1998). If the Quaternary and younger glaciations were responsible for the bulk of the valley's >1 km depth, we might expect apatite (U-Th)/He ages at the valley floor to be histories at these locations, these data constrain patterns of valley topography development through time. We also supplement these data with zircon 4He/3He thermochronometry, which is a newly developed method that provides information on continuous cooling paths through ~120-220 °C. We will present both the apatite and zircon 4He/3He data and, in conjunction with thermo-kinematic modeling, discuss the ability and limitations of these data to test models of Sierra Nevada topography development through time. Matthes (1930) USGS Professional Paper House et al. (1998) Nature McPhillips and Brandon (2012) American Journal of Science

  2. Systolic ventricular filling.

    Science.gov (United States)

    Torrent-Guasp, Francisco; Kocica, Mladen J; Corno, Antonio; Komeda, Masashi; Cox, James; Flotats, A; Ballester-Rodes, Manel; Carreras-Costa, Francesc

    2004-03-01

    The evidence of the ventricular myocardial band (VMB) has revealed unavoidable coherence and mutual coupling of form and function in the ventricular myocardium, making it possible to understand the principles governing electrical, mechanical and energetical events within the human heart. From the earliest Erasistratus' observations, principal mechanisms responsible for the ventricular filling have still remained obscured. Contemporary experimental and clinical investigations unequivocally support the attitude that only powerful suction force, developed by the normal ventricles, would be able to produce an efficient filling of the ventricular cavities. The true origin and the precise time frame for generating such force are still controversial. Elastic recoil and muscular contraction were the most commonly mentioned, but yet, still not clearly explained mechanisms involved in the ventricular suction. Classical concepts about timing of successive mechanical events during the cardiac cycle, also do not offer understandable insight into the mechanism of the ventricular filling. The net result is the current state of insufficient knowledge of systolic and particularly diastolic function of normal and diseased heart. Here we summarize experimental evidence and theoretical backgrounds, which could be useful in understanding the phenomenon of the ventricular filling. Anatomy of the VMB, and recent proofs for its segmental electrical and mechanical activation, undoubtedly indicates that ventricular filling is the consequence of an active muscular contraction. Contraction of the ascendent segment of the VMB, with simultaneous shortening and rectifying of its fibers, produces the paradoxical increase of the ventricular volume and lengthening of its long axis. Specific spatial arrangement of the ascendent segment fibers, their interaction with adjacent descendent segment fibers, elastic elements and intra-cavitary blood volume (hemoskeleton), explain the physical principles

  3. Early human-plant interactions based on palaeovegetation simulations of Africa over glacial-interglacial cycles

    Science.gov (United States)

    Cowling, S. A.; Cox, P. M.; Jones, C. D.; Maslin, M. A.; Spall, S. A.

    2003-04-01

    A greater understanding of African palaeovegetation environments over the Pleistocene (1.6 Mya) is important for evaluating potential catalysts underlying the anatomical, social and demographic changes observed in early human populations. We used a state-of-the-art fully-coupled earth system model (HADLEY-GCM3) to simulate typical glacial and interglacial environments likely encountered by late-Pleistocene humans. Our simulations indicate that tropical broadleaf forests of central Africa were not severely restricted by expanding grasslands during the last glacial maximum, although the carbon content of stem and density of leaf components were substantially reduced. We interpret a natural eastern migration corridor between southern Africa and the Rift Valley based on simulations of a no-analogue vegetation assemblage characterised by a unique combination of grass and low density forest. We postulate that early human populations in southern Africa were isolated from northern groups during warm interglacials, and that trans-African migration was facilitated during glacial cycles via a more openly forested eastern corridor.

  4. Modification of the land topography during glacial maximums due to the lithospheric flexure, temptative reconstructions of the southern North Sea landscapes during the Elsterian

    DEFF Research Database (Denmark)

    Moreau, Julien; Le Pourhiet, Laetitia; Grappe, Benjamin

    developed, stating that the incision and the filling of the valleys are separate in times and from distinct processes. The erosion surface and consequently the tunnel valleys peculiar incision geometry are preserved after ice recession, forming sediment traps. The infill is interpreted as proglacial...... overdeeps (the underfilled tunnel valleys). The presence of clinoforms 50-80 m above the valley shoulders indicates the potential depth of the lake. However, remains of the regionally extensive lake are elusive and seldom preserved onshore. We have hypothesised that the depression hosting the lake...

  5. Latest Pleistocene and Holocene surficial deposits and landforms of Yosemite Valley, California

    Science.gov (United States)

    Haddon, E. K.; Stock, G. M.; Booth, D. B.

    2016-12-01

    Field studies on the surficial geology and geomorphology of Yosemite Valley since the 1870's formed an early basis for our understanding of Quaternary landscape evolution in the central Sierra Nevada. These landmark studies described the erosional origin of Yosemite's iconic scenery, but left details of the latest Pleistocene and Holocene sedimentary record for later investigation. We combined mapping of deposits and landforms with geochronology to reconstruct the geomorphic evolution of Yosemite Valley since the 15 ka retreat of the Last Glacial Maximum (LGM) valley glacier. We document a sustained period of relative landscape stability, characterized by valley-bottom aggradation of glacial till, fluvial sediments, and lacustrine silts, as well as valley-margin accumulation of talus and fan alluvium. Recessional moraines, episodically emplaced rock avalanches, and alluvial fans impeded surface flow and controlled the local base level. This predominantly aggradational regime then shifted to incision in the earliest Holocene, likely due to a diminishing supply of glacial sediment, and created a flight of fluvial terraces inset by up to 9 m. The volume of fringing talus and fan alluvium in comparison with fluvial terrace sequences emphasizes the importance of valley-wall erosion as a sediment source. Cosmogenic 10Be exposure ages from rock avalanche boulders and 14C charcoal ages from deltaic sequences and inset fluvial gravels suggest variable rates of Holocene river incision. Although some incision events likely record local base level changes at the El Capitan LGM recessional moraine, the presence of perched, well-developed outwash terraces downstream indicates a more regional climatic forcing. These findings, including the depositional record of land-use disturbances over the past two centuries, help illuminate the geologic evolution of this celebrated landscape and inform ongoing river-restoration work.

  6. Modeled seasonality of glacial abrupt climate events

    NARCIS (Netherlands)

    Flueckiger, J.; Knutti, R.; White, J.W.C.; Renssen, H.

    2008-01-01

    Greenland ice cores, as well as many other paleo-archives from the northern hemisphere, recorded a series of 25 warm interstadial events, the so-called Dansgaard-Oeschger (D-O) events, during the last glacial period. We use the three-dimensional coupled global ocean-atmosphere-sea ice model

  7. Glacial Cycles and ice-sheet modelling

    NARCIS (Netherlands)

    Oerlemans, J.

    1982-01-01

    An attempt is made to simulate the Pleistocene glacial cycles with a numerical model of the Northern Hemisphere ice sheets. This model treats the vertically-integrated ice flow along a meridian, including computation of bedrock adjustment and temperature distribution in the ice. Basal melt water is

  8. Expanding Greenland’s Glacial Record

    DEFF Research Database (Denmark)

    Bjørk, Anders Anker

    . On order to expand the glacial history of Greenland, this thesis explores physical and geological archives for evidence of the glaciers’ past response to climatic variations. Using aerial photographs, the dynamic history of the Greenland Ice Sheet is extended back to 1900 C.E. Glacier changes covering...

  9. Effects of glacial/post-glacial weathering compared with hydrothermal alteration - implications for matrix diffusion. Results from drillcore studies in porphyritic quartz monzodiorite from Aespoe SE Sweden

    International Nuclear Information System (INIS)

    Landstroem, Ove; Tullborg, Eva-Lena

    2001-08-01

    The effects of hydrothermal + subsequent low temperature alteration and glacial/post-glacial weathering have been studied in two cores of quartz monzodiorite. One core (YA 1192) was drilled into the hydrothermally altered wall rock of a water-conducting fracture exposed at 170 m depth in the access tunnel to the Aespoe Hard Rock Laboratory. The other one (Bas 1) was drilled from an outcrop with a glacially polished surface, 1 km north of the YA 1192 site. Both drill cores were sectioned into mm-thick slices perpendicular to the core axis. The fracture filling of the YA 1192 core, the weathered surface of the BAS 1 core and the different slices were analysed for major and trace elements and isotopes of U and Th. The altered zone of the YA 1192 core extends to approx. 2.5 cm from the fracture surface. The alteration (mainly plagioclase → albite + sericite + epidote) has resulted in a higher porosity and formation of sorbing secondary minerals (e.g. sericite), favouring matrix diffusion. Increased Br concentrations in the altered zone are indicative of saline water in pores and micro fractures i.e. the presence of a diffusion medium. 234U/238U activity ratios > 1 and increased Cs in the altered zone are then interpreted as diffusion of U and Cs from fracture groundwater and subsequent sorption. The U migration is geologically recent (< 1 Ma). The 2.5 cm altered zone (corresponding to the zone of active matrix diffusion) significantly exceeds the visible red staining zone (0.5 cm) caused by hematite/FeOOH micrograins, emphasizing the need of microscopy to identify zones of alteration. The conspicuous weathering at the BAS 1 site is confined to a narrow rim of the bedrock surface (approx. 0.2-0.5 cm thick). Mass balance calculations for this rim (based on immobility of K) indicate that mechanical erosion has dominated over chemical dissolution processes (is roughly 10 times greater). The chemical weathering has affected mainly plagioclase and chlorite resulting in

  10. Influence of natural and anthropogenic factors on the distribution of xerothermic plants in the lower San river valley (SE Poland

    Directory of Open Access Journals (Sweden)

    Rafał Krawczyk

    2012-12-01

    Full Text Available The aim of the present study was to describe the distribution of xerothermic species of vascular plants in the lower San River valley and the relationship between their density and the intensity of selected environmental (natural and anthropogenic factors. Xerothermic species occurred more frequently in the present valley floor compared to the glacial terrace. Within the present valley, the highest density was observed in the floodplain. The examined species also occurred more often on steep slopes of the valley, at the margins of the present valley terraces, and in the area of occurrence of aeolian sands. Moreover, a positive correlation has been found between the number of xerothermic species and the area of polyhemeroby ecosystems. The distribution of xero- and thermophilous species is determined by natural edaphic and geomorphological factors as well as anthropogenic ones (land use, lowering of the groundwater level as a result of river regulation.

  11. Electrical resistivity tomography (ERT surveys on glacial deposits in Romanian Carpathians

    Directory of Open Access Journals (Sweden)

    Andrei ZAMOSTEANU

    2014-11-01

    Full Text Available The study presents preliminary results regarding the use of electrical resistivity surveys in the assessment of the internal structure of the glacial deposits from the Romanian Carpathians.ERT is a geophysical method used to quantify changes in electrical resistivity of the ground towards passing electric current across an array of electrodes and simultaneous measurement of the induced potential gradient. Using specific software the measurements are further processed and correlated with the topography in order to obtain bedrock resistivity features. Therefore, the method is useful to evaluate the characteristics of geological strata and is widely used for mapping shallow subsurface geological structures. In the mountain regions ERT studies have been applied in different glacial and periglacial geomorphological studies - for permafrost detection (in Romanian Carpathians - Urdea et. al., 2008; Vespremeanu-Stroe et al., 2012, slope deformation analysis, the assessment of slip surface depths, sediment thickness, groundwater levels etc. One of the most commonly 2-D array used is the Wenner electrode configuration, which is moderately sensitive to both horizontal and vertical ground structures.Due to their elevations and Pleistocene’s climatic conditions, the Romanian Carpathians have been partially affected by Quaternary glaciations. The glaciers descended to about 1050-1200 m a.s.l. (Urdea and Reurther, 2009 in the Transylvanian Alps and Rodna Mountains (Eastern Carpathians carving a large number of U-shaped valleys and glacial cirques (Mîndrescu, 2006 and forming accumulations of unconsolidated glacial debris (moraines. Our study areas are two sites located in the northern (Rodna Mts. and southern (Iezer Păpuşa Mts. part of the mountain range.

  12. Asynchronous Glacial Chronologies in the Central Andes (15-40°S) and Paleoclimatic Implications

    Science.gov (United States)

    Zech, R.; Kull, C.; Kubik, P. W.; Veit, H.

    2006-12-01

    We have established glacial chronologies along a N-S transect over the Central Andes using 10Be surface exposure dating. Our results show that maximum glacial advances occurred asynchronously and reflect the varying influence and shifts of the major atmospheric circulation systems during the Late Quaternary: the tropical circulation in the north and the westerlies in the south. In Bolivia (three research areas in the Cordillera Real and the Cordillera Cochabamba, ~15°S) glacial advances could be dated to ~20 and 12 ka BP. This is in good agreement with published exposure age data from moraines in Bolivia and Peru (provided that all ages are calculated following the same scaling system). Accordingly, the maximum glaciation there probably occurred roughly synchronous to the temperature minimum of the global Last Glacial Maximum (LGM) and the lateglacial cold reversals. Strict correlation with neither the Younger Dryas in the northern hemisphere, nor the Antarctic Cold Reversal is possible due to the current systematic exposure age uncertainties (~10%). Glacier-Climate-Modelling corroborates the sensitivity of the reconstructed glaciers to temperature changes, rather than precipitation. On the contrary, there is good evidence for the dominant role of precipitation changes on the glacial chronologies in the lee of the Cordillera Occidental, i.e. on the Altiplano and further south. The pronounced lateglacial wet phase, which is well documented in lake transgression phases as far south as 28°S (-> tropical moisture source), seems to have caused glacial advances even at ~30°S. In two research areas in Chile at that latitude, we were able to date several lateglacial moraines. Besides, the maximum datable glaciation there occurred at ~30 ka BP. That is significantly earlier than the LGM (sensu strictu) and points to favourable climate conditions for glaciation at that time (particularly increased precipitation). We conclude that the westerlies were more intensive or

  13. Dye filled security seal

    International Nuclear Information System (INIS)

    Wilson, D.C.

    1982-01-01

    A security seal for providing an indication of unauthorized access to a sealed object includes an elongate member to be entwined in the object such that access is denied unless the member is removed. The elongate member has a hollow, pressurizable chamber extending throughout its length that is filled with a permanent dye under greater than atmospheric pressure. Attempts to cut the member and weld it together are revealed when dye flows through a rupture in the chamber wall and stains the outside surface of the member

  14. Benign gastric filling defect

    International Nuclear Information System (INIS)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y.

    1979-01-01

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  15. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y. [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  16. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K K; Lee, Y H; Cho, O K; Park, C Y [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  17. Identification of glacier motion and potentially dangerous glacial lakes in the Mt. Everest region/Nepal using spaceborne imagery

    Directory of Open Access Journals (Sweden)

    T. Bolch

    2008-12-01

    Full Text Available Failures of glacial lake dams can cause outburst floods and represents a serious hazard. The potential danger of outburst floods depends on various factors like the lake's area and volume, glacier change, morphometry of the glacier and its surrounding moraines and valley, and glacier velocity. Remote sensing offers an efficient tool for displacement calculations and risk assessment of the identification of potentially dangerous glacial lakes (PDGLs and is especially helpful for remote mountainous areas. Not all important parameters can, however, be obtained using spaceborne imagery. Additional interpretation by an expert is required. ASTER data has a suitable accuracy to calculate surface velocity. Ikonos data offers more detail but requires more effort for rectification. All investigated debris-covered glacier tongues show areas with no or very slow movement rates. From 1962 to 2003 the number and area of glacial lakes increased, dominated by the occurrence and almost linear areal expansion of the moraine-dammed lakes, like the Imja Lake. Although the Imja Lake will probably still grow in the near future, the risk of an outburst flood (GLOF is considered not higher than for other glacial lakes in the area. Potentially dangerous lakes and areas of lake development are identified. There is a high probability of further lake development at Khumbu Glacier, but a low one at Lhotse Glacier.

  18. Glacial heritage: knowledge, inventory and promotion in the Chablais area (France, Switzerland)

    Science.gov (United States)

    Perret, A.; Reynard, E.; Delannoy, J.-J.

    2012-04-01

    This study is part of an Interreg IVA project (www.123chablais.com) dealing with the promotion of different types of natural and cultural heritage in the Chablais area (French and Swiss Prealps) and is linked to the candidature of the French Chablais territory for the European Geoparks Network. The objective of the study is to develop a strategy for the promotion of the glacial heritage (landforms, deposits) in an area where the geomorphological features are highly influenced by glacial history and where key concepts in the Quaternary sciences were developed (e.g. the theory of multiple glaciations by Morlot in 1859), but that is now nearly completely deglaciated. The challenge is to find solutions to explain why the glacial heritage is so important for the regional economy and how it influences the life of inhabitants (e.g. Evian and Thonon mineral water, extraction industry, landscape and tourism), even if glaciers are not so impressive than in other parts of the Alps. The research is divided in three parts. (1) The first one aims to enhance knowledge on glacial landforms and deposits. The study area, that is quite large, has been intensively studied for more than two centuries; nevertheless, some parts have been only poorly studied. Intensive field survey was carried out to fill in the gaps of knowledge and some landforms, such as erratic boulders, have been dated in order to establish a chronology of deglaciation. All of these different elements have been included in a Geographic Information System with the aim of establishing maps of glacial stages in the Chablais area. (2) From this, an inventory of glacial geosites has been carried out, using the assessment method developed by Reynard et al. (2007). A specific focus has been on the assessment of the potential of the selected sites for educational purposes and geotourist promotion. (3) The last part has been the preparation of adapted educational and promotional supports. In particular, an exhibition will be

  19. Modeled post-glacial landscape evolution at the southern margin of the Laurentide Ice Sheet: hydrological connection of uplands controls the pace and style of fluvial network expansion

    Science.gov (United States)

    Lai, J.; Anders, A. M.

    2017-12-01

    Landscapes of the US Midwest were repeatedly affected by the southern margin of the Laurentide Ice Sheet during the Quaternary. Glacial processes removed pre-glacial relief and left constructional landforms including low-relief till plains and high-relief moraines. As the ice retreated, meltwater was collected in subglacial or proglacial lakes and outburst floods of glacial lakes episodically carved deep valleys. These valleys provided the majority of post-glacial landscape relief. However, a significant fraction of the area of low-relief till plains was occupied by closed depressions and remained unconnected to these meltwater valleys. This area is referred to as non-contributing area (NCA) because it does not typically contribute surface runoff to stream networks. Decreasing fractions of NCA on older glacial landscape surfaces suggests that NCA becomes integrated into external drainage networks over time. We propose that this integration could occur via two different paths: 1) through capture of NCA as channel heads propagate into the upland or, 2) through erosion of a channel along a flow path that, perhaps intermittently, connects NCA to the external drainage network. We refer the two cases as "disconnected" and "connected" cases since the crucial difference between them is the hydrological connectivity on the upland. We investigate the differences in the evolution of channel networks and morphology in low relief landscapes under disconnected and connected drainage regimes through numerical simulations of fluvial and hillslope processes. We observe a substantially faster evolution of the channel network in the connected case than in the disconnected case. Modeled landscapes show that channel network in the connected case has longer, more sinuous channels. We also find that the connected case removes lower amounts of total mass than the disconnected case when the same degree of channel integration is achieved. Observed landscapes in US Midwest are more

  20. The amount of glacial erosion of the bedrock

    International Nuclear Information System (INIS)

    Paasse, Tore

    2004-11-01

    The purpose of this study is to estimate an upper bound for the average erosion of fresh bedrock that can reasonably be expected during a glacial period or a single glaciation. The study is based on the assumption that classic sediments, formed by Scandinavian ice erosion during the Quaternary period, still exist within the formerly glaciated area or its periphery. The volume of these sediments thus constitutes the maximum average glacial erosion of bedrock within this area. This volume is calculated by estimating the thickness of the minerogenic Quaternary from well data in Sweden and Denmark and from seismic measurements in adjacent sea areas. The average thickness of the Quaternary deposits and other reogolith in the investigated area was estimated to 16 m. Assuming that the whole volume is the result of glacial erosion of fresh bedrock this corresponds to 12 m depth. However, a great part of the sediments may consist of glacially redistributed Tertiary regolith. As the amount of Tertiary regolith is uncertain the estimated maximum average glacial erosion rate in fresh bedrock is uncertain, and assuming that the total sediment volume is the result of glacial erosion leads to an overestimation of the glacial erosion depth. Considering this, the average glacial erosion during a full glacial period has been estimated to between 0.2 m and 4 m. If the extremes in the made assumptions are excluded the glacial erosion during a glacial cycle can be estimated to about 1 m

  1. The amount of glacial erosion of the bedrock

    Energy Technology Data Exchange (ETDEWEB)

    Paasse, Tore [Geological Survey of Sweden, Uppsala (Sweden)

    2004-11-01

    The purpose of this study is to estimate an upper bound for the average erosion of fresh bedrock that can reasonably be expected during a glacial period or a single glaciation. The study is based on the assumption that classic sediments, formed by Scandinavian ice erosion during the Quaternary period, still exist within the formerly glaciated area or its periphery. The volume of these sediments thus constitutes the maximum average glacial erosion of bedrock within this area. This volume is calculated by estimating the thickness of the minerogenic Quaternary from well data in Sweden and Denmark and from seismic measurements in adjacent sea areas. The average thickness of the Quaternary deposits and other reogolith in the investigated area was estimated to 16 m. Assuming that the whole volume is the result of glacial erosion of fresh bedrock this corresponds to 12 m depth. However, a great part of the sediments may consist of glacially redistributed Tertiary regolith. As the amount of Tertiary regolith is uncertain the estimated maximum average glacial erosion rate in fresh bedrock is uncertain, and assuming that the total sediment volume is the result of glacial erosion leads to an overestimation of the glacial erosion depth. Considering this, the average glacial erosion during a full glacial period has been estimated to between 0.2 m and 4 m. If the extremes in the made assumptions are excluded the glacial erosion during a glacial cycle can be estimated to about 1 m.

  2. Relative timing of last glacial maximum and late-glacial events in the central tropical Andes

    Science.gov (United States)

    Bromley, Gordon R. M.; Schaefer, Joerg M.; Winckler, Gisela; Hall, Brenda L.; Todd, Claire E.; Rademaker, Kurt M.

    2009-11-01

    Whether or not tropical climate fluctuated in synchrony with global events during the Late Pleistocene is a key problem in climate research. However, the timing of past climate changes in the tropics remains controversial, with a number of recent studies reporting that tropical ice age climate is out of phase with global events. Here, we present geomorphic evidence and an in-situ cosmogenic 3He surface-exposure chronology from Nevado Coropuna, southern Peru, showing that glaciers underwent at least two significant advances during the Late Pleistocene prior to Holocene warming. Comparison of our glacial-geomorphic map at Nevado Coropuna to mid-latitude reconstructions yields a striking similarity between Last Glacial Maximum (LGM) and Late-Glacial sequences in tropical and temperate regions. Exposure ages constraining the maximum and end of the older advance at Nevado Coropuna range between 24.5 and 25.3 ka, and between 16.7 and 21.1 ka, respectively, depending on the cosmogenic production rate scaling model used. Similarly, the mean age of the younger event ranges from 10 to 13 ka. This implies that (1) the LGM and the onset of deglaciation in southern Peru occurred no earlier than at higher latitudes and (2) that a significant Late-Glacial event occurred, most likely prior to the Holocene, coherent with the glacial record from mid and high latitudes. The time elapsed between the end of the LGM and the Late-Glacial event at Nevado Coropuna is independent of scaling model and matches the period between the LGM termination and Late-Glacial reversal in classic mid-latitude records, suggesting that these events in both tropical and temperate regions were in phase.

  3. An improved active contour model for glacial lake extraction

    Science.gov (United States)

    Zhao, H.; Chen, F.; Zhang, M.

    2017-12-01

    Active contour model is a widely used method in visual tracking and image segmentation. Under the driven of objective function, the initial curve defined in active contour model will evolve to a stable condition - a desired result in given image. As a typical region-based active contour model, C-V model has a good effect on weak boundaries detection and anti noise ability which shows great potential in glacial lake extraction. Glacial lake is a sensitive indicator for reflecting global climate change, therefore accurate delineate glacial lake boundaries is essential to evaluate hydrologic environment and living environment. However, the current method in glacial lake extraction mainly contains water index method and recognition classification method are diffcult to directly applied in large scale glacial lake extraction due to the diversity of glacial lakes and masses impacted factors in the image, such as image noise, shadows, snow and ice, etc. Regarding the abovementioned advantanges of C-V model and diffcults in glacial lake extraction, we introduce the signed pressure force function to improve the C-V model for adapting to processing of glacial lake extraction. To inspect the effect of glacial lake extraction results, three typical glacial lake development sites were selected, include Altai mountains, Centre Himalayas, South-eastern Tibet, and Landsat8 OLI imagery was conducted as experiment data source, Google earth imagery as reference data for varifying the results. The experiment consequence suggests that improved active contour model we proposed can effectively discriminate the glacial lakes from complex backgound with a higher Kappa Coefficient - 0.895, especially in some small glacial lakes which belongs to weak information in the image. Our finding provide a new approach to improved accuracy under the condition of large proportion of small glacial lakes and the possibility for automated glacial lake mapping in large-scale area.

  4. Geomorphic investigation of the Late-Quaternary landforms in the southern Zanskar Valley, NW Himalaya

    Science.gov (United States)

    Sharma, Shubhra; Hussain, Aadil; Mishra, Amit K.; Lone, Aasif; Solanki, Tarun; Khan, Mohammad Khatib

    2018-02-01

    The Suru, Doda and Zanskar river valleys in the semi-arid region of Southern Zanskar Ranges (SZR) preserve a rich repository of the glacial and fluvial landforms, alluvial fans, and lacustrine deposits. Based on detailed field observations, geomorphic mapping and limited optical ages, we suggest four glaciations of decreasing magnitude in the SZR. The oldest Southern Zanskar Glaciation Stage (SZS-4) is inferred from glacially polished bedrock and tillite pinnacles. The SZS-4 is ascribed to the Marine Isotopic Stage (MIS)-4/3. The subsequent SZS-3 is represented by obliterated and dissected moraines, and is assigned to MIS-2/Last Glacial Maximum. The multiple recessional moraines of SZS-2 glaciation are assigned the early to mid Holocene age whereas, the youngest SZS-1 moraines were deposited during the Little Ice Age. We suggest that during the SZS-2 glaciation, the Drang-Drung glacier shifted its course from Suru Valley (west) to the Doda Valley (east). The study area has preserved three generations of outwash gravel terraces, which broadly correlate with the phases of deglaciation associated with SZS-3, 2, and 1. The alluvial fan aggradation, lacustrine sedimentation, and loess deposition occurred during the mid-to-late Holocene. We suggest that glaciation was driven by a combination of the mid-latitude westerlies and the Indian Summer Monsoon during periods of cooler temperature, while phases of deglaciation occurred during enhanced temperature.

  5. Simulation of channel sandstone architecture in an incised valley

    Energy Technology Data Exchange (ETDEWEB)

    Frykman, P.; Johannessen, P.; Andsbjerg, J.

    1998-12-31

    The present report describes a geostatistical modelling study that is aimed at reflecting the architecture of the channel sandstones in an incised valley fill. The example used for this study is a part of the Middle Jurassic sandy succession of the Bryne Formation in the Danish central Graben. The succession consists mainly of fluvial sediments in the lower part, overlain by tidal influenced sediments, which again is overlain by shallow marine sediments. The modelling study has been performed on a sequence of incised valley sediments in the upper part of the Bryne Formation overlying fluvial sediments. (au) EFP-96. 19 refs.

  6. Preparing for faster filling

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Following the programmed technical stop last week, operators focussed on preparing the machine for faster filling, which includes multibunch injection and a faster pre-cycle phase.   The LHC1 screen shot during the first multibunch injection operation. The LHC operational schedule incorporates a technical stop for preventive maintenance roughly every six weeks of stable operation, during which several interventions on the various machines are carried out. Last week these included the replacement of a faulty magnet in the SPS pre-accelerator, which required the subsequent re-setting of the system of particle extraction and transfer to the LHC. At the end of last week, all the machines were handed back for operation and work could start on accommodating all the changes made into the complex systems in order for normal operation to be resumed. These ‘recovery’ operations continued through the weekend and into this week. At the beginning of this week, operators succeeded in pro...

  7. Hydrogeologic and geochemical characterization of groundwater resources in Deep Creek Valley and adjacent areas, Juab and Tooele Counties, Utah, and Elko and White Pine Counties, Nevada

    Science.gov (United States)

    Gardner, Philip M.; Masbruch, Melissa D.

    2015-09-18

    The water resources of Deep Creek Valley were assessed during 2012–13 with an emphasis on better understanding the groundwater flow system and groundwater budget. Surface-water resources are limited in Deep Creek Valley and are generally used for agriculture. Groundwater is the predominant water source for most other uses and to supplement irrigation. Most groundwater withdrawal in Deep Creek Valley occurs from the unconsolidated basin-fill deposits, in which conditions are generally unconfined near the mountain front and confined in the lower-altitude parts of the valley. Productive aquifers are also present in fractured bedrock that occurs along the valley margins and beneath the basin-fill deposits. The consolidated-rock and basin-fill aquifers are hydraulically connected in many areas with much of the recharge occurring in the consolidated-rock mountain blocks and most of the discharge occurring from the lower-altitude basin-fill deposits.

  8. Are glacials "dry" - and in what sense?

    Science.gov (United States)

    Scheff, J.; Seager, R.; Coats, S.; Liu, H.

    2016-12-01

    Glacial maxima during the Pleistocene are generally thought to be arid on land, with a few regional exceptions. Recent work on future climate change, however, has found that different wetness-related variables have opposite-signed responses over large portions of the continents, belying simple ideas of local "drying" or "wetting" with global temperature change in models. Here, we show that this behavior extends to simulations of the Last Glacial Maximum as well: the continents are modeled to have generally wetter topsoils and higher values of standard climate-wetness metrics in the LGM than in the preindustrial, as well as generally lower precipitation and ubiquitously lower photosynthesis (likely driven by the low CO2), with the streamflow response falling in between. Is this model-derived view of the LGM an accurate one? Using a large community pollen and plant-fossil compilation, we confirm that LGM grasslands and open woodlands grew at many sites of present potential forest, seasonal or dry forests at many sites of present potential rain- or seasonal forests, and so forth, while changes in the opposite sense were extremely few and spatially confined. We show that this strongly resembles the simulated photosynthesis changes, but not the simulated streamflow or soil moisture changes. Meanwhile, published LGM lake-level estimates resemble the simulated streamflow changes, but not the photosynthesis changes. Thus, the last glacial does not appear to be systematically "dry" outside the high latitudes, but merely carbon-starved. Similarly, local findings of reduced or more open vegetation at the LGM (e.g. from pollen, carbon isotopes, or dustiness) do not indicate local "aridity" unless corroborating hydrological proxies are also found. Finally, this work suggests that glacial-era evidence of open vegetation with high lake levels (as in the eastern Mediterranean) is not odd or paradoxical, but entirely consistent with climate model output.

  9. Modelling end-glacial earthquakes at Olkiluoto

    International Nuclear Information System (INIS)

    Faelth, B.; Hoekmark, H.

    2011-02-01

    The objective of this study is to obtain estimates of the possible effects that post-glacial seismic events in three verified deformation zones (BFZ100, BFZ021/099 and BFZ214) at the Olkiluoto site may have on nearby fractures in terms of induced fracture shear displacement. The study is carried out by use of large-scale models analysed dynamically with the three dimensional distinct element code 3DEC. Earthquakes are simulated in a schematic way; large planar discontinuities representing earthquake faults are surrounded by a number of smaller discontinuities which represent rock fractures in which shear displacements potentially could be induced by the effects of the slipping fault. Initial stresses, based on best estimates of the present-day in situ stresses and on state-of-the-art calculations of glacially-induced stresses, are applied. The fault rupture is then initiated at a pre-defined hypocentre and programmed to propagate outward along the fault plane with a specified rupture velocity until it is arrested at the boundary of the prescribed rupture area. Fault geometries, fracture orientations, in situ stress model and material property parameter values are based on data obtained from the Olkiluoto site investigations. Glacially-induced stresses are obtained from state-of-the-art ice-crust/mantle finite element analyses. The response of the surrounding smaller discontinuities, i.e. the induced fracture shear displacement, is the main output from the simulations

  10. New Insights Into Valley Formation and Preservation: Geophysical Imaging of the Offshore Trinity River Paleovalley

    Science.gov (United States)

    Speed, C. M.; Swartz, J. M.; Gulick, S. P. S.; Goff, J.

    2017-12-01

    The Trinity River paleovalley is an offshore stratigraphic structure located on the inner continental shelf of the Gulf of Mexico offshore Galveston, Texas. Its formation is linked to the paleo-Trinity system as it existed across the continental shelf during the last glacial period. Newly acquired high-resolution geophysical data have imaged more complexity to the valley morphology and shelf stratigraphy than was previously captured. Significantly, the paleo-Trinity River valley appears to change in the degree of confinement and relief relative to the surrounding strata. Proximal to the modern shoreline, the interpreted time-transgressive erosive surface formed by the paleo-river system is broad and rugose with no single valley, but just 5 km farther offshore the system appears to become confined to a 10 km wide valley structure before again becoming unconfined once again 30 km offshore. Fluvial stratigraphy in this region has a similar degree of complexity in morphology and preservation. A dense geophysical survey of several hundred km is planned for Fall 2017, which will provide unprecedented imaging of the paleovalley morphology and associated stratigraphy. Our analysis leverages robust chirp processing techniques that allow for imaging of strata on the decimeter scale. We will integrate our geophysical results with a wide array of both newly collected and previously published sediment cores. This approach will allow us to address several key questions regarding incised valley formation and preservation on glacial-interglacial timescales including: to what extent do paleo-rivers remain confined within a single broad valley structure, what is the fluvial systems response to transgression, and what stratigraphy is created and preserved at the transition from fluvial to estuarine environments? Our work illustrates that traditional models of incised valley formation and subsequent infilling potentially fail to capture the full breadth of dynamics of past river

  11. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  12. Analysis of overdeepened valleys using the digital elevation model of the bedrock surface of Northern Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, P.

    2010-11-15

    Based on surface and borehole information, together with pre-existing regional and local interpretations, a 7,150 square kilometre Raster Digital Elevation Model (DEM) of the bedrock surface of northern Switzerland was constructed using a 25 m cell size. This model represents a further important step in the understanding of Quaternary sediment distribution and is open to a broad field of application and analysis, including hydrogeological, geotechnical and geophysical studies as well as research in the field of Pleistocene landscape evolution. An analysis of the overdeepened valleys in the whole model area and, more specifically in the Reuss area, shows that, in most cases, overdeepening is restricted to the areas covered by the Last Glaciation Maximum (LGM). However, at various locations relatively narrow overdeepened valleys outreach the tongue basins and the LGM ice shield limits. Therefore, an earlier and further-reaching glacial event has probably contributed significantly to the overdeepening of these valleys. No significant overdeepening has been identified downstream of Boettstein (Aare) and Kaiserstuhl (Rhine), although the ice extended considerably further downstream, at least during the most extensive glaciation. Except for the bedrock between Brugg and Boettstein, no overdeepened valleys are found significantly north of the outcrop of Mesozoic limestone of the Folded and Tabular Jura. A detailed analysis of the Reuss area shows that the Lake and Suhre valleys are separated from the Emmen-Gisikon Reuss valley basin by a significant bedrock barrier. The individual bedrock valleys are divided into several sub-basins, indicating a multiphase evolution of the valleys. Some of the swells or barriers separating the sub-basins coincide with known late LGM retreat stages. In the Suhre valley, an old fluvial valley floor with restricted overdeepened sections is documented. (author)

  13. Last Glacial Maximum Dated by Means of 10Be in the Maritime Alps (Italy)

    Science.gov (United States)

    Granger, D. E.; Spagnolo, M.; Federici, P.; Pappalardo, M.; Ribolini, A.; Cyr, A. J.

    2006-12-01

    Relatively few exposure dates of LGM moraines boulders are available for the European Alps, and none on the southern flank. Ponte Murato (PM) is a frontal moraine at 860 m asl in the Gesso Basin (Maritime Alps, SW European Alps). The PM moraine dams the 157 km2 Gesso della Barra Valley and it represents the lowermost frontal moraine of the entire Gesso Valley, near the outlet of the valley in the Po Plain. Its ELA, determined from the paleo- shape of the supposed Gesso della Barra glacier, is 1746 m asl. Tetti Bandito (TB) is a small and badly preserved glacial deposit, tentatively attributed to a lateral-frontal moraine, that is positioned 5 km downvalley from the PM deposit at 800 m asl. There are no other glacial deposits downvalley from the TB moraine in the Gesso Basin or farther NE in the piedmont region of the upper Po Plain. Boulders sampled on the PM and on the TB moraine crests gave a 10Be cosmogenic age of respectively 16300 ± 880 ka (average value) and 18798 ± 973 ka. This result constrains the PM frontal moraine within the LGM interval but also suggests that the maximum expansion of the Gesso Basin glacier was more downvalley at some point during the last glaciation. If the TB is a lateral-frontal moraine as supposed, the two TB and PM moraines would represent the outer and inner moraine crests of the same LGM stadial, with the outer moraine much less pronounced than the inner moraine, similarly to the maximalstand and the hochstand described in the Eastern Alps (Van Husen, 1997). Within this perspective, the PM and TB dates are consistent with a European Alps LGM corresponding to MIS 2 (Ivy-Ochs et al., 2004). This study of the Maritime Alps moraines is also in agreement with the Upper Würm climatic theory (Florineth and Schlüchter, 2000) of a stronger influence of the W and SW incoming humid airflows in the European Alps, differently from the nearby Vosges and Pyrenees mountain chains where more dry conditions were probably responsible for a very

  14. Multiple origins of large hummock deposits in Alai Valley, Northern Pamir: Implications for palaeoclimate reconstructions

    Science.gov (United States)

    Reznichenko, N. V.; Andrews, G. R.; Geater, R. E.; Strom, A.

    2017-05-01

    This paper interprets the origin of several of the largest hummocky landform assemblages in the Alai Valley, Northern Pamir - a formerly glaciated intermontane depression. The vast hummocky deposits in the Koman-Suu and Achik-Tash river catchments are found to be of two contrasting modes of formation: glacial hummocks deposited during Koman and Lenin Glaciers withdraw and avalanche hummocks produced during catastrophic Koman and Lenin rock avalanches. The origins of the deposits we assessed through remote and field-based geomorphological mapping, as well as sedimentological investigations, which included clast analysis and the identification of micro-scale agglomerates indicative of rock avalanche emplacement. Both the Koman and Lenin rock avalanches were large, catastrophic events (with run-outs of 34 and 24 km, respectively, and a volume over 1 × 109 m3 each) that occurred subsequent to glacier withdrawal from the area. The complex conditions on the moment of the rock avalanche emplacement promoted unusual deposits geomorphology and extensive run-outs. The landslide landforms formed over the pre-existing glacial hummocks and fluvial deposits, and are geomorphologically and sedimentologically distinct from the larger glacial hummocks. The reconstruction of this sequence of events has implications for how hummock dating should be interpreted. This research illustrates large scale catastrophic landsliding in the glacial environment, and adds to the ongoing debate about the misidentification of rock avalanche deposits as of glacial origin, and their relevance to palaeoclimatological and palaeoseismological reconstructions.

  15. Micro-hole and multigrain quartz luminescence dating of Paleodeltas at Lake Fryxell, McMurdo Dry Valleys (Antarctica), and relevance for lake history

    DEFF Research Database (Denmark)

    Berger, G.W.; Doran, P.T.; Thomsen, Kristina Jørkov

    2013-01-01

    Relict (perched) lacustrine deltas around the perennially ice-covered lakes in the Taylor Valley, Antarctica, imply that these lakes were up to 40 times larger in area than at present since the last glacial maximum (LGM). These deltas have been used to constrain ice-margin positions in Taylor Val...

  16. Breathing Valley Fever

    Centers for Disease Control (CDC) Podcasts

    2014-02-04

    Dr. Duc Vugia, chief of the Infectious Diseases Branch in the California Department of Public Health, discusses Valley Fever.  Created: 2/4/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/5/2014.

  17. Evidence of a low-latitude glacial buzzsaw: Progressive hypsometry reveals height-limiting glacial erosion in tropical mountain belts

    Science.gov (United States)

    Cunningham, M.; Stark, C. P.; Kaplan, M. R.; Schaefer, J. M.; Winckler, G.

    2017-12-01

    It has been widely demonstrated that glacial erosion limits the height of mid-latitude mountain ranges—a phenomenon commonly referred to as the "glacial buzzsaw." The strength of the buzzsaw is thought to diminish, or die out completely, at lower latitudes, where glacial landscapes occupy only a small part of mountain belts affected by Pleistocene glaciation. Here we argue that glacial erosion has actually truncated the rise of many tropical orogens. To elicit signs of height-limiting glacial erosion in the tropics, we employ a new take on an old tool: we identify transient geomorphic features by tracking the evolution of (sub)catchment hypsometry with increasing elevation above base level, a method we term "progressive hypsometry." In several tropical mountain belts, including the Central Range of Taiwan, the Talamanca of Costa Rica, the Finisterres of Papua New Guinea, and the Rwenzoris of East Africa, progressive hypsometry reveals transient landscapes perched at various elevations, but the highest of these transient features are consistently glacial landscapes near the lower limit of late-Pleistocene glacial equilibrium line altitude (ELA) fluctuation. We attribute this pattern to an efficient glacial buzzsaw. In many cases, these glacial landscapes are undergoing contemporary destruction by headward propagating, fluvially-driven escarpments. We deduce that a duel between glacial buzzcutting and fluvially-driven scarp propagation has been ongoing throughout the Pleistocene in these places, and that the preservation potential of tropical glacial landscapes is low. To this end, we have identified possible remnants of glacial landscapes in the final stages of scarp consumption, and use 3He surface exposure age dating of boulders and bedrock surfaces in two of these landscapes to constrain major geomorphic activity to before the onset of the Last Glacial Maximum. Our work points to a profound climatic influence on the evolution of these warm, tectonically active

  18. The understanding of the formation of valleys and its implication on site characterization: Moredalen and Pukedalen, south-eastern Sweden

    International Nuclear Information System (INIS)

    Tiren, Sven A.; Waenstedt, Stefan; Straeng, Thomas

    2010-11-01

    In south-eastern Sweden, there are a number of over-deepened narrow valleys, more than 20 m deep, formed in Precambrian bedrock located above the highest post-glacial shoreline. Canyon-like valleys, called 'kursu' or kursu valleys, are generally interpreted to be formed by glaciofluvial erosion. An example of such a valley is Moredalen, a canyon in the Fennoscandian Shield, which has an implication on site selection for radioactive waste disposal. There are also more open over-deepened valleys along which sub-glacial flow has occurred, e.g. Pukedalen. The main part of this paper discusses a combined geological and geophysical investigation of Moredalen, with the aim to investigate possible reasons for the formation of such an unusual feature formed in acid vulcanite and foliated tonalitic to granodioritic rocks. Moredalen is a marked, approximately 7 km long, E-W striking valley that cuts through a plateau (c. 140 m a.s.l.), and an elevated block of the sub-Cambrian peneplain. Glaciofluvial sediments can be found up-streams where the canyon widens to the west. Just east of the valley is a larger delta deposited at the highest post-glacial shoreline (c. 105 m a.s.l). Further east of, and in line with the Moredalen valley there is an esker. Rock debris in the valley is angular. Pukedalen is a northwest-southeast trending valley incised in massive granite. The valley is in its northern parts relatively open and becomes narrow in its south-eastern part having partly a vertical south-western wall. Rock surfaces are smooth along the valley and rock debris in the valley consists generally of rounded blocks. In line with Pukedalen, on both sides at great distances though, there are eskers. Geomorphological features of this kind indicate certain characteristics of the bedrock that need to be considered during safety analysis of repositories for nuclear waste. The distinct weakness zones along which the kursu-valleys are formed create prominent transport paths for

  19. The understanding of the formation of valleys and its implication on site characterization: Moredalen and Pukedalen, south-eastern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Tiren, Sven A.; Waenstedt, Stefan; Straeng, Thomas (GEOSIGMA AB (Sweden))

    2010-11-15

    In south-eastern Sweden, there are a number of over-deepened narrow valleys, more than 20 m deep, formed in Precambrian bedrock located above the highest post-glacial shoreline. Canyon-like valleys, called 'kursu' or kursu valleys, are generally interpreted to be formed by glaciofluvial erosion. An example of such a valley is Moredalen, a canyon in the Fennoscandian Shield, which has an implication on site selection for radioactive waste disposal. There are also more open over-deepened valleys along which sub-glacial flow has occurred, e.g. Pukedalen. The main part of this paper discusses a combined geological and geophysical investigation of Moredalen, with the aim to investigate possible reasons for the formation of such an unusual feature formed in acid vulcanite and foliated tonalitic to granodioritic rocks. Moredalen is a marked, approximately 7 km long, E-W striking valley that cuts through a plateau (c. 140 m a.s.l.), and an elevated block of the sub-Cambrian peneplain. Glaciofluvial sediments can be found up-streams where the canyon widens to the west. Just east of the valley is a larger delta deposited at the highest post-glacial shoreline (c. 105 m a.s.l). Further east of, and in line with the Moredalen valley there is an esker. Rock debris in the valley is angular. Pukedalen is a northwest-southeast trending valley incised in massive granite. The valley is in its northern parts relatively open and becomes narrow in its south-eastern part having partly a vertical south-western wall. Rock surfaces are smooth along the valley and rock debris in the valley consists generally of rounded blocks. In line with Pukedalen, on both sides at great distances though, there are eskers. Geomorphological features of this kind indicate certain characteristics of the bedrock that need to be considered during safety analysis of repositories for nuclear waste. The distinct weakness zones along which the kursu-valleys are formed create prominent transport paths for

  20. Earth's glacial record and its tectonic setting

    Science.gov (United States)

    Eyles, N.

    1993-09-01

    Glaciations have occurred episodically at different time intervals and for different durations in Earth's history. Ice covers have formed in a wide range of plate tectonic and structural settings but the bulk of Earth's glacial record can be shown to have been deposited and preserved in basins within extensional settings. In such basins, source area uplift and basin subsidence fulfill the tectonic preconditions for the initiation of glaciation and the accomodation and preservation of glaciclastic sediments. Tectonic setting, in particular subsidence rates, also dictates the type of glaciclastic facies and facies successions that are deposited. Many pre-Pleistocene glaciated basins commonly contain well-defined tectonostratigraphic successions recording the interplay of tectonics and sedimentation; traditional climatostratigraphic approaches involving interpretation in terms of either ice advance/retreat cycles or glacio-eustatic sea-level change require revision. The direct record of continental glaciation in Earth history, in the form of classically-recognised continental glacial landforms and "tillites", is meagre; it is probable that more than 95% of the volume of preserved "glacial" strata are glacially-influenced marine deposits that record delivery of large amounts of glaciclastic sediment to offshore basins. This flux has been partially or completely reworked by "normal" sedimentary processes such that the record of glaciation and climate change is recorded in marine successions and is difficult to decipher. The dominant "glacial" facies in the rock record are subaqueous debris flow diamictites and turbidites recording the selective preservation of poorly-sorted glaciclastic sediment deposited in deep water basins by sediment gravity flows. However, these facies are also typical of many non-glacial settings, especially volcanically-influenced environments; numerous Archean and Proterozoic diamictites, described in the older literature as tillites, have no

  1. Geomorphic legacy of medieval Himalayan earthquakes in the Pokhara Valley

    Science.gov (United States)

    Schwanghart, Wolfgang; Bernhardt, Anne; Stolle, Amelie; Hoelzmann, Philipp; Adhikari, Basanta R.; Andermann, Christoff; Tofelde, Stefanie; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

    2016-04-01

    The Himalayas and their foreland belong to the world's most earthquake-prone regions. With millions of people at risk from severe ground shaking and associated damages, reliable data on the spatial and temporal occurrence of past major earthquakes is urgently needed to inform seismic risk analysis. Beyond the instrumental record such information has been largely based on historical accounts and trench studies. Written records provide evidence for damages and fatalities, yet are difficult to interpret when derived from the far-field. Trench studies, in turn, offer information on rupture histories, lengths and displacements along faults but involve high chronological uncertainties and fail to record earthquakes that do not rupture the surface. Thus, additional and independent information is required for developing reliable earthquake histories. Here, we present exceptionally well-dated evidence of catastrophic valley infill in the Pokhara Valley, Nepal. Bayesian calibration of radiocarbon dates from peat beds, plant macrofossils, and humic silts in fine-grained tributary sediments yields a robust age distribution that matches the timing of nearby M>8 earthquakes in ~1100, 1255, and 1344 AD. The upstream dip of tributary valley fills and X-ray fluorescence spectrometry of their provenance rule out local sediment sources. Instead, geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation and debris flows that had plugged several tributaries with tens of meters of calcareous sediment from the Annapurna Massif >60 km away. The landscape-changing consequences of past large Himalayan earthquakes have so far been elusive. Catastrophic aggradation in the wake of two historically documented medieval earthquakes and one inferred from trench studies underscores that Himalayan valley fills should be considered as potential archives of past earthquakes. Such valley fills are pervasive in the Lesser Himalaya though high erosion rates reduce

  2. Post-glacial landform evolution in the middle Satluj River valley, India

    Indian Academy of Sciences (India)

    unit-III). This is fol- lowed by ∼4 m ... whereas, the matrix-supported gravel suggests irregular and flashy discharge with dominance ..... grain size data, interpretation is based on visual observations in the field which allow identifica- tion of six ...

  3. Late Quaternary geomorphic history of a glacial landscape - new sedimentary and chronological data from the Cordillera de Cochabamba (Bolivia)

    Science.gov (United States)

    May, J.-H.; Preusser, F.; Zech, R.; Ilgner, J.; Veit, H.

    2009-04-01

    Throughout the Central Andes, glacial landscapes have long been used for the reconstruction of Late Quaternary glaciations and landscape evolution. Much work has focused on the Andes in Peru, Chile and the Bolivian Altiplano, whereas relatively little data has been published on glaciation history in the eastern Andean ranges and slopes. Even less is known with regard to the postglacial evolution of these glacial landscapes. In the Cordillera de Cochabamba (Bolivia), local maximum advances probably peaked around 20-25 ka BP and were followed by significant readvances between ~12-16 ka BP. This generally points to temperature controlled maximum glacial advances along the humid eastern slopes of the Central Andes, which is supported by glacier-climate-modelling studies. However, most studies include only marginal information with regard to the complex geomorphic and sedimentary situation in the Cordillera de Cochabamba. Furthermore, the chronological results are afflicted with several methodological uncertainties inherent to surface exposure dating and call for application of alternative, independent age dating methods. Therefore this study aims at i) documenting and interpreting the complex glacial geomorphology of the Huara Loma valley in the Cordillera de Cochabamba (Bolivia), ii) analyzing the involved units of glacial sediments, and iii) improving the chronological framework by applying optically stimulated luminescence (OSL) and radiocarbon dating (14C). For this purpose, geomorphic mapping was combined with field documentation of sedimentary profiles. The involved sediments were subject to geochemical and mineralogical analysis in order to deduce information on their erosional and weathering histories. In addition, the interpretation of OSL ages from glacial and proglacial sediments integrated several methodological procedures with regard to sample preparation and statistical analysis of the measurements in order to increase the degree of confidence. These

  4. Seismic response of the geologic structure underlying the Roman Colosseum and a 2-D resonance of a sediment valley

    Directory of Open Access Journals (Sweden)

    P. Labak

    1995-06-01

    Full Text Available The seismic response of the geologic structure beneath the Colosseum is investigated using a two-dimensional modeling for a vertically incident plane SH wave. Computations indicate that the southern part of the Colosseum may be exposed to a seismic ground motion with significantly larger amplitudes, differential motion and longer duration than the northern part. because the southern part of the Colosseum is underlain by a sedimentfilled valley created by sedimentary filling of the former tributary of the River Tiber. A 2-D resonance may develop in the valley. Unlike the previous theoretical studies on 2-D resonance in sediment-filled valleys, an effect of heterogeneous valley surroundings on the resonance is partly investigated. A very small sensitivity of the maximum spectral amplifications connected with the fundamental and first higher modes to the presence of a horizontal surface layer (with an intermediate velocity in the valley surroundings is observed in the studied models.

  5. A transient fully coupled climate-ice-sheet simulation of the last glacial inception

    Science.gov (United States)

    Lofverstrom, M.; Otto-Bliesner, B. L.; Lipscomb, W. H.; Fyke, J. G.; Marshall, S.; Sacks, B.; Brady, E. C.

    2017-12-01

    The last glacial inception occurred around 115 ka, following a relative minimum in the Northern Hemisphere summer insolation. It is believed that small and spatially separated ice caps initially formed in the high elevation regions of northern Canada, Scandinavia, and along the Siberian Arctic coast. These ice caps subsequently migrated down in the valleys where they coalesced and formed the initial seeds of the large coherent ice masses that covered the northern parts of the North American and Eurasian continents over most of the last glacial cycle. Sea level records show that the initial growth period lasted for about 10 kyrs, and the resulting ice sheets may have lowered the global sea level by as much as 30 to 50 meters. Here we examine the transient climate system evolution over the period between 118 and 110 ka, using the fully coupled Community Earth System Model, version 2 (CESM2). This model features a two-way coupled high-resolution (4x4 km) ice-sheet component (Community Ice Sheet model, version 2; CISM2) that simulates ice sheets as an interactive component of the climate system. We impose a transient forcing protocol where the greenhouse gas concentrations and the orbital parameters follow the nominal year in the simulation; the model topography is also dynamically evolving in order to reflect changes in ice elevation throughout the simulation. The analysis focuses on how the climate system evolves over this time interval, with a special focus on glacial inception in the high-latitude continents. Results will highlight how the evolving ice sheets compare to data and previous model based reconstructions.

  6. Little Ice Age glacial geomorphology and sedimentology of Portage Glacier, South-Central Alaska

    Directory of Open Access Journals (Sweden)

    Carlos Córdova

    2009-06-01

    Full Text Available The study of glacial landforms and deposits is important, as it isdifficult to observe processes under modern glaciers and ice-sheets. Thus landscapes and sediments that are the product of present glaciation can give insight into processes that occurred during Pleistocene times. This study investigates the genesis of little ice age glacial landforms present in Portage Glacier, South-Central Alaska. The present day moraine morphology and sedimentology in Portage Glacier valley reveals the presence of two types of till and moraines. The clast-rich sandy diamicton present on the 1852 moraine is interpreted to be a basal till indicating this feature is a pushmoraine representing an advance or a standstill position of Portage Glacier in 1852. The moderately sorted gray sandy boulder gravel present on the 1900 and 1922 moraines is interpreted to be an ice-marginal deposit (ablation till with a mixture of supraglacial and glaciofluvial sediments deposited by slumping and stream sortingprocesses. All of these features are interpreted to be ablation moraines representing glacier retreat and moraine building in 1900 and1922.

  7. Precise chronologies of Holocene glacial culminations in the Cordillera Vilcabamba of southern Peru

    Science.gov (United States)

    Licciardi, J. M.; Schaefer, J. M.; Schweinsberg, A. D.

    2012-12-01

    Records of past fluctuations in climatically sensitive tropical mountain glaciers are among the best indicators of regional paleoclimatic trends and controls. The majority of the world's present-day tropical glaciers are found in the Peruvian Andes, but accurate and precise chronologies of past glacial activity in this region remain relatively scarce, particularly during the Holocene. Here we present ~50 new 10Be exposure ages derived from boulders on well-preserved moraine successions in several glaciated drainages in the Cordillera Vilcabamba of southern Peru (13°20'S latitude). The new results suggest that prominent moraines in these valleys are correlative with previously published moraine ages near Nevado Salcantay in this range (Licciardi et al., 2009), but also expand on the initial surface exposure chronologies to reveal additional periods of glacier stabilization not found in previous work. A provisional composite chronology that merges the new and previously obtained moraine ages indicates at least five discrete glacial culminations from the Lateglacial to the late Holocene. Forthcoming 10Be ages from an additional ~50 samples collected from moraine boulders will increase the precision and completeness of the Vilcabamba moraine chronologies. Basal radiocarbon ages are being developed from bog and lake sediments in stratigraphic contact with the 10Be-dated moraines. These new 14C age data will help constrain the local cosmogenic 10Be production rate, thereby increasing the accuracy of the 10Be chronologies.

  8. Potentially dangerous glacial lakes in Kyrgyzstan - Research overview of 2004-2015

    Science.gov (United States)

    Jansky, Bohumir; Yerokhin, Sergey; Sobr, Miroslav; Engel, Zbynek; Cerny, Michal; Falatkova, Kristyna; Kocum, Jan; Benes, Vojtech

    2016-04-01

    Global warming causes intensive melting and retreat of glaciers in most of high mountains all over the world. This process is also evident in the mountain regions of central Tien Shan. Glacier melt water affects changes in hydrological regime of water streams and causes overfilling of high mountain lake basins. The dams of many lakes are very unstable and can burst open. To determine the degree of such risk, it is necessary to analyse the genesis of lakes, to characterize the morphology of the lake basins and to know the particularities of their hydrological regime. According to the latest inventory within territory of Kyrgyzstan, a total of 1328 lakes have been identified as potentially dangerous, 12 lakes are considered as currently dangerous, other 25 feature high potential hazard. Since 1952 more than 70 disastrous cases of lake outburst have been registered. The hazardous alpine lakes are studied in Kyrgyzstan systematically since 1966. Since 2004, Czech-Kyrgyz research team has been operating in Kyrgyzstan in the field of dangerous glacial lakes. Projects were focused primarily on high-mountain glacial lakes risk assessment, propositions of risk mitigation measures, establishment of permanent research station near one of the studied glacier complexes, preparation of risk analysis for selected endangered valleys, evaluation of climatic and hydrological data and glacier development within observed regions. The most significant portion of data and information has been gathered during field work, complemented by satellite image analysis and surveillance flights over the monitored sites.

  9. Gas-filled hohlraum fabrication

    International Nuclear Information System (INIS)

    Salazar, M.A.; Gobby, P.L.; Foreman, L.R.; Bush, H. Jr.; Gomez, V.M.; Moore, J.E.; Stone, G.F.

    1995-01-01

    Los Alamos National Laboratory (LANL) researchers have fabricated and fielded gas-filled hohlraums at the Lawrence Livermore National Laboratory (LLNL) Nova laser. Fill pressures of 1--5 atmospheres have been typical. We describe the production of the parts, their assembly and fielding. Emphasis is placed on the production of gas-tight polyimide windows and the fielding apparatus and procedure

  10. Monitoring of Bashkara glacial lakes (the Central Caucasus) and modelling of their potential outburst.

    Science.gov (United States)

    Krylenko, I.; Norin, S.; Petrakov, D.; Tutubalina, O.; Chernomorets, S.

    2009-04-01

    In recent decades due to glacier retreat the glacial lakes in the Central Caucasus, as well as in other high-mountainous areas of the world, have expanded intensively. As result the risk of lake outbursts and destructive floods is raising. In this paper we present one of the most potentially hazardous lakes of this region - a group of glacial lakes near the Bashkara glacier in the upper Adylsu river valley, to the southeast of Mt. Elbrus. Total area of these lakes is about 100,000m2, and a total volume exceeds 1,000,000 m3. The biggest of them - the Bashkara lake has formed in late 1930s - early 1940s and the small Lapa lake has appeared in the end of 1980s. The Bashkara lake outburst occurred twice in the end of 1950s and produced devastating debris flows of ca. 2 million m3. We have monitored these lakes since 1999. Our work includes detailed field research: constant measurements of water level during warm period, annually repeated bathymetric surveys, geodetic surveys, observations on dam condition and some special measurements (i.e. water temperature distribution, current velocity). Also we use aerial and satellite images to obtain data about dynamic of areas for the lakes. From 2001 to 2006 years volume of the Lapa lake has increased 5 times (from 30,000 m3 to 140,000 m3), the Bashkara lake in this period was quasi-stable. In 2006-2008 volume of the Lapa lake has decreased due to sedimentation, however, rapid growth of water level in Bashkara lake (more than 20 sm. per day) has suddenly begun. As a result, volume of the Bashkara lake exceeded 1,000000 m3 in July 2008 whereas in 2001 -2007 year it was about 800,000 m3. Previous maximum of water level was exceeded on 3,5 m, moraine dam with ice core was overtopped and overflow has started. Thus, Bashkara glacier lakes are unstable and risk of outburst is increasing. To assess parameters and zones of potential outburst flood in the Adylsu River valley we have carried out hydrodynamic simulation. Two computer

  11. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.; Cachim, P.B.; Da Costa, Pedro M. F. J.

    2014-01-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  12. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.

    2014-04-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  13. Interhemispheric correlation of late pleistocene glacial events.

    Science.gov (United States)

    Lowell, T V; Heusser, C J; Andersen, B G; Moreno, P I; Hauser, A; Heusser, L E; Schlüchter, C; Marchant, D R; Denton, G H

    1995-09-15

    A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and >/=33,500 carbon-14 years before present ((14)C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000(14)C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720(14)C yr B.P., and at the beginning of the Younger Dryas at 11,050 (14)C yr B. P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges.

  14. Modeled seasonality of glacial abrupt climate events

    Energy Technology Data Exchange (ETDEWEB)

    Flueckiger, Jacqueline [Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO (United States); Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zuerich, Zurich (Switzerland); Knutti, Reto [Institute for Atmospheric and Climate Science, ETH Zuerich, Zurich (Switzerland); White, James W.C. [Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO (United States); Renssen, Hans [Vrije Universiteit Amsterdam, Faculty of Earth and Life Sciences, Amsterdam (Netherlands)

    2008-11-15

    Greenland ice cores, as well as many other paleo-archives from the northern hemisphere, recorded a series of 25 warm interstadial events, the so-called Dansgaard-Oeschger (D-O) events, during the last glacial period. We use the three-dimensional coupled global ocean-atmosphere-sea ice model ECBILT-CLIO and force it with freshwater input into the North Atlantic to simulate abrupt glacial climate events, which we use as analogues for D-O events. We focus our analysis on the Northern Hemisphere. The simulated events show large differences in the regional and seasonal distribution of the temperature and precipitation changes. While the temperature changes in high northern latitudes and in the North Atlantic region are dominated by winter changes, the largest temperature increases in most other land regions are seen in spring. Smallest changes over land are found during the summer months. Our model simulations also demonstrate that the temperature and precipitation change patterns for different intensifications of the Atlantic meridional overturning circulation are not linear. The extent of the transitions varies, and local non-linearities influence the amplitude of the annual mean response as well as the response in different seasons. Implications for the interpretation of paleo-records are discussed. (orig.)

  15. Testing MODFLOW-LGR for simulating flow around Buried Quaternary valleys - synthetic test cases

    DEFF Research Database (Denmark)

    Vilhelmsen, Troels Norvin; Christensen, Steen

    In Denmark the water supply is entirely based on ground water. In some parts of the country these resources are found in buried quaternary tunnel valleys. Intensive mapping has shown that the valleys typically have a complex internal hydrogeology with multiple cut and ­fill structures....... The administration of groundwater resources has been based on simulations using regional scale groundwater models. However, regional scale models have difficulties with accurately resolving the complex geology of the buried valleys, which bears the risk of poor model predictions of local scale effects of groundwater...

  16. Glacial rebound and crustal stress in Finland

    International Nuclear Information System (INIS)

    Lambeck, K.; Purcell, A.

    2003-11-01

    The last ice age of Fennoscandinavia continues to have geological repercussions across Finland despite the last ice having retreated almost 10,000 years ago: land uplift, shoreline retreat, and the stress state of the crust continues to evolve. This report focusses on the glacial rebound signals for Finland and the Gulf of Bothnia and explores the consequences of the ongoing deformation. The rebound signals include the geological evidence as well as instrumental observations: the tide gauge and lake-level measurements of the past century, the changes in geodetic levels recorded in the repeat levelling surveys of the region and the direct measurement of crustal deformation (radial and horizontal) using high-precision space-geodesy measurements. These signals provide constraints on the Earth's rheology, its elasticity and viscosity, and the glacial history of the region. Once observationally constrained, the rebound models are used to predict both the ongoing evolution of shorelines and the changing state of stress within the crust. This report covers: (i) A review of glacial rebound modelling for Scandinavia (Sections 2 and 3). (ii) Review of observational evidence relating to sea-level change and crustal rebound (Section 4). (iii) New earth and ice-sheet model results from the inversion of the geological evidence for sea-level change, including models of shoreline evolution (Sections 5 and 6). (iv) Earth-model results from the inversion of the geodetic evidence for sea-level change (Section 7). (v) Development of crustal stress models for past and present stress states (Section 8). (vi) Conclusions and recommendations (Section 9). Specific conclusions reached pertain to: (i) Thickness of ice cover over Scandinavia since the Last Glacial Maximum, particularly for the Lateglacial period. (ii) Sea-level change and shoreline evolution for the Baltic area since the time the region became ice-free for the last time. (iii) The predicted rates of present-day crustal

  17. Lithologic influences on groundwater recharge through incised glacial till from profile to regional scales: Evidence from glaciated Eastern Nebraska

    Science.gov (United States)

    Gates, John B.; Steele, Gregory V.; Nasta, Paolo; Szilagyi, Jozsef

    2014-01-01

    Variability in sediment hydraulic properties associated with landscape depositional and erosional features can influence groundwater recharge processes by affecting soil-water storage and transmission. This study considers recharge to aquifers underlying river-incised glaciated terrain where the distribution of clay-rich till is largely intact in upland locations but has been removed by alluvial erosion in stream valleys. In a stream-dissected glacial region in eastern Nebraska (Great Plains region of the United States), recharge estimates were developed for nested profile, aquifer, and regional scales using unsaturated zone profile measurements (matric potentials, Cl- and 3H), groundwater tracers (CFC-12 and SF6), and a remote sensing-assisted water balance model. Results show a consistent influence of till lithology on recharge rates across nested spatial scales despite substantial uncertainty in all recharge estimation methods, suggesting that minimal diffuse recharge occurs through upland glacial till lithology whereas diffuse recharge occurs in river valleys where till is locally absent. Diffuse recharge is estimated to account for a maximum of 61% of total recharge based on comparison of diffuse recharge estimated from the unsaturated zone (0-43 mm yr-1) and total recharge estimated from groundwater tracers (median 58 mm yr-1) and water balance modeling (median 56 mm yr-1). The results underscore the importance of lithologic controls on the distributions of both recharge rates and mechanisms.

  18. Andean glacial lakes and climate variability since the last glacial maximum

    Directory of Open Access Journals (Sweden)

    1995-01-01

    Full Text Available LES LACS GLACIAIRES ET LA VARIABILITÉ CLIMATIQUE DANS LES ANDES DEPUIS LE DERNIER MAXIMUM GLACIAIRE. Des carottages réalisés dans des lacs glaciaires des Andes tropicales et subtropicales ont fourni des registres paléoclimatiques continus couvrant le Dernier Maximum Glaciaire et l’Holocène. Des datations 14C sur sédiments lacustres et sur tourbes indiquent que le maximum de la dernière glaciation s’est produit antérieurement au Dernier Maximum Glaciaire Global (18 ka BP. La plupart des lacs ont un âge inférieur à 13 ka BP, ce qui signifie que l’avancée des glaciers correspondant au Pleistocène terminal aurait culminé aux alentours de 14 ka BP. Des avancées durant le Tardi-glaciaire sont enregistrées dans plusieurs sites lacustres. À partir de 10 ka BP, les glaciers ont reculé au-delà de leurs limites actuelles. La sécheresse de l’Holocène moyen est repérée dans la stratigraphie de nombre de lacs, y compris le lac Titicaca. Cette phase d’aridité est suivie par une remontée des niveaux lacustres et une réavancée des glaciers à la fin de l’Holocène. LAGOS GLACIARES ANDINOS Y VARIABILIDAD CLIMÁTICA DESDE EL ÚLTIMO MÁXIMO GLACIAL. Testigos de sedimentos de los lagos glaciares en los Andes tropicales/subtropicales proporcionan registros continuos de los paleoclimas del último glacial superior y del Holoceno. Dataciones del radiocarbón de los sedimentos profundos en los lagos y de las turberas indican que el máximo del último glacial fue antes del máximo glacial global con una fecha de 18 14C ka BP. La mayoría de los lagos tienen una antigüedad menor de 13 14C ka BP, lo que significa que hubo una fase de glaciación del Pleistoceno superior culminada alrededor de 14 14C ka BP. Los avances durante el glacial superior son indicados en varios testigos de sedimentos de los lagos y, después de 10 14C ka BP, los glaciares quedaron dentro de sus límites actuales. Una sequía durante el Holoceno medio est

  19. Alpine glacial topography and the rate of rock column uplift

    DEFF Research Database (Denmark)

    Pedersen, Vivi Kathrine; Egholm, D.L.; Nielsen, S.B.

    2010-01-01

    The present study investigates the influence of alpine glacial erosion on the morphology and relief distribution of mountain regions associated with varying rock column uplift rates. We take a global approach and analyse the surface area distribution of all mountain regions affected by glacial er...

  20. Effects of glacial meltwater on corrosion of copper canisters

    International Nuclear Information System (INIS)

    Ahonen, L.; Vieno, T.

    1994-08-01

    The composition of glacial meltwater and its reactions in the bedrock are examined. The evidences that there are or should be from past intrusions of glacial meltwater and oxygen deep in the bedrock are also considered. The study is concluded with an evaluation of the potential effects of oxygenated meltwater on the corrosion of copper canisters. (46 refs., 3 figs., 2 tabs.)

  1. New exposure ages for the Last Glacial Cycle in the Sanabria Lake region (northwestern Spain)

    Science.gov (United States)

    Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; Domínguez-Cuesta, María Jose; Rinterknecht, Vincent; Pallàs, Raimon; Braucher, Régis; Bourlès, Didier; Valero-Garcés, Blas

    2013-04-01

    ., 2011. Last deglaciation in northwestern Spain: New chronological and geomorphologic evidence from the Sanabria region. Geomorphology 135, 48-65. Palacios, D., Andrés, N., Úbeda, J., Alcalá, J., Marcos, J., Vázquez-Selem, L., 2012. The importance of poligenic moraines in the paleoclimatic interpretation from cosmogenic dating. Geophysical Research Abstracts 14, EGU2012-3759-1. Pérez-Alberti, A., Valcárcel-Díaz, M., Martini, I.P., Pascucci, V., Andrucci, S., 2011. Upper Pleistocene glacial valley-junction sediments at Pias, Trevinca Mountains, NW Spain. In: Martini, I.P., French, H.M., Pérez-Alberti, A. (Eds.), Ice-Marginal and Periglacial Processes and Sediments. Geological Society (London) Special Publication 354, pp. 93-110. Research funded by the projects LIMNOCLIBER (REN2003-09130-C02-02), IBERLIMNO (CGL2005-20236-E/CLI), LIMNOCAL (CGL2006-13327-C04-01) and GRACCIE (CSD2007-00067) of the Spanish Inter-Ministry Commission of Science and Technology (CICYT). Additional funding was provided by the Fundación Patrimonio Natural de Castilla y León through the project "La investigacion en el Lago de Sanabria dentro del proyecto CALIBRE: perspectivas y posibilidades", and by the projects Consolider Ingenio 2006 (CSD2006-0041, Topo-Iberia), 2003 PIRA 00256, HF02.4, and RISKNAT (2009SGR520). L. Rodríguez-Rodríguez has developed her research under a Severo Ochoa Programme fellowship (FICYT- Asturias).

  2. Radiopacity of root filling materials

    International Nuclear Information System (INIS)

    Beyer-Olsen, E.M.

    1983-01-01

    A method for measuring the radiopacity of root filling materials is described. Direct measurements were made of the optic density values of the materials in comparison with a standard curve relating optic density to the thickness of an aluminium step wedge exposed simultaneously. By proper selection of film and conditions for exposure and development, it was possible to obtain a near-linear standard curve which added to the safety and reproducibility of the method. The technique of radiographic assessment was modified from clinical procedures in evaluating the obturation in radiographs, and it was aimed at detecting slits or voids between the dental wall and the filling material. This radiographic assessment of potensial leakage was compared with actual in vitro lekage of dye (basic fuchsin) into the roots of filled teeth. The result of the investigation show that root filling materials display a very wide range of radiopacity, from less than 3 mm to more than 12 mm of aluminium. It also seem that tooth roots that appear to be well obturated by radiographic evaluation, stand a good chance of beeing resistant to leakage in vitro, and that the type of filling material rather than its radiographic appearance, determines the susceptibility of the filled tooth to leakage in vitro. As an appendix the report contains a survey of radiopaque additives in root filling materials

  3. Hydrogeologic framework and occurrence, movement, and chemical characterization of groundwater in Dixie Valley, west-central Nevada

    Science.gov (United States)

    Huntington, Jena M.; Garcia, C. Amanda; Rosen, Michael R.

    2014-01-01

    Dixie Valley, a primarily undeveloped basin in west-central Nevada, is being considered for groundwater exportation. Proposed pumping would occur from the basin-fill aquifer. In response to proposed exportation, the U.S. Geological Survey, in cooperation with the Bureau of Reclamation and Churchill County, conducted a study to improve the understanding of groundwater resources in Dixie Valley. The objective of this report is to characterize the hydrogeologic framework, the occurrence and movement of groundwater, the general water quality of the basin-fill aquifer, and the potential mixing between basin-fill and geothermal aquifers in Dixie Valley. Various types of geologic, hydrologic, and geochemical data were compiled from previous studies and collected in support of this study. Hydrogeologic units in Dixie Valley were defined to characterize rocks and sediments with similar lithologies and hydraulic properties influencing groundwater flow. Hydraulic properties of the basin-fill deposits were characterized by transmissivity estimated from aquifer tests and specific-capacity tests. Groundwater-level measurements and hydrogeologic-unit data were combined to create a potentiometric surface map and to characterize groundwater occurrence and movement. Subsurface inflow from adjacent valleys into Dixie Valley through the basin-fill aquifer was evaluated using hydraulic gradients and Darcy flux computations. The chemical signature and groundwater quality of the Dixie Valley basin-fill aquifer, and potential mixing between basin-fill and geothermal aquifers, were evaluated using chemical data collected from wells and springs during the current study and from previous investigations. Dixie Valley is the terminus of the Dixie Valley flow system, which includes Pleasant, Jersey, Fairview, Stingaree, Cowkick, and Eastgate Valleys. The freshwater aquifer in the study area is composed of unconsolidated basin-fill deposits of Quaternary age. The basin-fill hydrogeologic unit

  4. 77 FR 33237 - Saline Valley Warm Springs Management Plan/Environmental Impact Statement, Death Valley National...

    Science.gov (United States)

    2012-06-05

    ... Valley Warm Springs Management Plan/Environmental Impact Statement, Death Valley National Park, Inyo... an Environmental Impact Statement for the Saline Valley Warm Springs Management Plan, Death Valley... analysis process for the Saline Valley Warm Springs Management Plan for Death Valley [[Page 33238...

  5. Quaternary glacial stratigraphy and chronology of Mexico

    Science.gov (United States)

    White, Sidney E.

    The volcano Iztaccihuatl in central Mexico was glaciated twice during the middle Pleistocene, once probably in pre-Illinoian (or pre-Bull Lake) time, and once in late Illinoian (or Bull Lake) time. Glaciation during the late Pleistocene was restricted to the late Wisconsin (or Pinedale). A maximum advance and one readvance are recorded in the early part, and one readvance in the latter part. Three or four small neoglacial advances occurred during the Holocene. Two other volcanoes nearby, Ajusco and Malinche, have a partial record of late Pleistocene and Holocene glaciations. Three others, Popocatépetl, Pico de Orizaba, and Nevado de Toluca, have a full Holocene record of three to five glacial advances during Neoglaciation.

  6. Removal of root filling materials.

    LENUS (Irish Health Repository)

    Duncan, H.F. Chong, B.S.

    2011-05-01

    Safe, successful and effective removal of root filling materials is an integral component of non-surgical root canal re-treatment. Access to the root canal system must be achieved in order to negotiate to the canal terminus so that deficiencies in the original treatment can be rectified. Since a range of materials have been advocated for filling root canals, different techniques are required for their removal. The management of commonly encountered root filling materials during non-surgical re-treatment, including the clinical procedures necessary for removal and the associated risks, are reviewed. As gutta-percha is the most widely used and accepted root filling material, there is a greater emphasis on its removal in this review.

  7. Dissolved organic matter export in glacial and non-glacial streams along the Gulf of Alaska

    Science.gov (United States)

    Hood, E. W.; Scott, D.; Jeffery, A.; Schreiber, S.; Heavner, M.; Edwards, R.; D'Amore, D. V.; Fellman, J.

    2009-12-01

    The Gulf of Alaska drainage basin contains more than 75,000 km2 of glaciers, many of which are rapidly thinning and receding. We are using a paired watershed approach to evaluate how changes in glacier ecosystems will impact the export dissolved organic matter (DOM) into the Gulf of Alaska. Our primary study watersheds, Lemon Creek and Montana Creek, are similar in size, bedrock lithology and elevation range and extend from near sea level to the margin or interior of the Juneau Icefield. Lemon Creek has a glacial coverage of ~60%, while Montana Creek is free of glacier ice. Our goal is to evaluate seasonal differences in the quantity, chemical character and reactivity of DOM being exported from these watersheds to downstream near-shore marine ecosystems. In addition, we are monitoring a variety of physical parameters that influence instream DOM metabolism in both watersheds. Our initial results from the 2009 runoff season indicate that concentrations of dissolved organic carbon (DOC) are substantially higher in the non-glacial watershed. However, fluorescence analyses indicate that DOM from the glacier watershed has a higher protein and lower humic material content compared to DOM from the non-glacial watershed. After the spring snowmelt season, physical parameters between the two watersheds diverged, with higher streamflow and turbidity as well as colder water temperatures in the glacial watershed. Although our previous yield calculations show significantly higher DOC fluxes from the forested watershed, our results here suggest that glacier watersheds may be an important source of labile carbon to the near shore marine ecosystem. The contrast in the physical habitat between the two rivers (e.g glacier stream = cold, low light penetration, unstable substrate) supports the hypothesis that that in-stream DOM processing is limited within glacier dominated rivers, therefore delivering a higher percentage of labile DOM downstream.

  8. Glacial refugia and post-glacial colonization patterns in European bryophytes

    OpenAIRE

    Kyrkjeeide, Magni Olsen; Stenøien, Hans K.; Flatberg, Kjell Ivar; Hassel, Kristian

    2014-01-01

    Most species are assumed to have survived south or east of the ice sheet covering northern Europe during the last glacial maximum. Molecular and macrofossil evidence suggests, however, that some species may have survived in ice-free areas in Scandinavia. In plants, inbreeding and vegetative growth are associated with low genetic load and enhanced survival in small, isolated populations. These characteristics are often found in bryophytes, possibly allowing them to survive extreme conditions i...

  9. The California Valley grassland

    Science.gov (United States)

    Keeley, J.E.; Schoenherr, Allan A.

    1990-01-01

    Grasslands are distributed throughout California from Oregon to Baja California Norte and from the coast to the desert (Brown 1982) (Figure 1). This review will focus on the dominant formation in cismontane California, a community referred to as Valley Grassland (Munz 1959). Today, Valley Grassland is dominated by non-native annual grasses in genera such as Avena (wild oat), Bromus (brome grass), and Hordeum (barley), and is often referred to as the California annual grassland. On localized sites, native perennial bunchgrasses such as Stipa pultra (purple needle grass) may dominate and such sites are interpreted to be remnants of the pristine valley grassland. In northwestern California a floristically distinct formation of the Valley Grassland, known as Coast Prairie (Munz 1959) or Northern Coastal Grassland (Holland and Keil 1989) is recognized. The dominant grasses include many native perennial bunchgrasses in genera such as Agrostis, Calamagrostis, Danthonia, Deschampsia, Festuca, Koeleria and Poa (Heady et al. 1977). Non-native annuals do not dominate, but on some sites non-native perennials like Anthoxanthum odoratum may colonize the native grassland (Foin and Hektner 1986). Elevationally, California's grasslands extend from sea level to at leas 1500 m. The upper boundary is vague because montane grassland formations are commonly referred to as meadows; a community which Munz (1959) does not recognize. Holland and Keil (1989) describe the montane meadow as an azonal community; that is, a community restricted not so much to a particular climatic zone but rather controlled by substrate characteristics. They consider poor soil-drainage an over-riding factor in the development of montane meadows and, in contrast to grasslands, meadows often remain green through the summer drought. Floristically, meadows are composed of graminoids; Cyperaceae, Juncaceae, and rhizomatous grasses such as Agropyron (wheat grass). Some bunchgrasses, such as Muhlenbergia rigens, are

  10. Glacial lakes in South Tyrol: distribution, evolution and potential for GLOFs

    Science.gov (United States)

    Schug, Marie-Claire; Mergili, Martin

    2017-04-01

    All over the world glaciers are currently retreating, leading to the formation or growth of glacial lakes. Some of these lakes are susceptible to sudden drainage. In order to assess the danger of glacial lake outburst floods (GLOFs) in South Tyrol in the Italian Alps, we present (i) an inventory of lakes, (ii) an analysis of the development of selected glacial lakes since 1945, and (iii) the susceptibility to and the possible impact areas of GLOFs. The inventory includes 1010 lakes that are larger than 250 m2 at an elevation above 2000 m asl, most of them of glacial origin. These lakes are mapped manually from orthophotos. Apart from collecting information on the spatial distribution of these lakes, the inventory lists dam material, glacier contact, and further parameters. 89% of the lakes in the investigation area are impounded by bedrock, whereas 93% of the lakes are detached from the associated glacier. The majority of lakes is small to medium sized (selected lakes are analyzed in detail in the field and from multi-temporal orthophotos, including the development of lake size and surroundings in the period since 1945. The majority of the selected lakes, however, was first recorded on orthophotos from the early 1980s. Eight of ten lakes grew significantly in that period. But when the lakes detached from the glacier until the early 2000s, the growth slowed down or ceased. Based on the current development of the selected lakes we conclude that the close surroundings of these lakes have stabilised and the lakes' susceptibility to an outburst has thus decreased. We further conduct broad-scale analyses of the susceptibility of the mapped lakes to GLOFs, and of the potential reach of possible GLOFs. The tool r.glachaz is used to determine the potentially dangerous lakes. Even though some few lakes require closer attention, the overall susceptibility to GLOFs in South Tyrol is relatively low, as most lakes are impounded by bedrock. In some cases, GLOFs caused by impact

  11. Late Mesolithic hunting of a small female aurochs in the valley of the River Tjonger (the Netherlands) in the light of Mesolithic aurochs hunting in NW Europe

    NARCIS (Netherlands)

    Prummel, W.; Niekus, M.J.L.Th.

    The valley of the River Tjonger, situated in the Province of Friesland (the Netherlands), is rich in prehistoric organic remains. The fill of the valley, consisting of waterlogged sediments (peat, gyttja and sands), presents favourable conditions for the preservation of bone, antler and botanical

  12. A continuous record of glacial-interglacial cycles spanning more than 500 kyr from Lake Junín, Perú

    Science.gov (United States)

    Rodbell, D. T.; Abbott, M. B.; McGee, D.; Chen, C. Y.; Stoner, J. S.; Hatfield, R. G.; Tapia, P. M.; Bush, M. B.; Weidhaas, N.; Woods, A.; Valero-Garces, B. L.; Lehmann, S. B.; Bustamante, M. G.; Larsen, D. J.

    2017-12-01

    Lake Junín (11.0°S, 76.2°W) is a shallow (zmax 12 m), intermontane, high-elevation (4080 masl) lake in the inner-tropics of the Southern Hemisphere that spans 300 km2. It is dammed by coalescing alluvial fans that are >250 ka that emanate from glacial valleys. Lake Junín has not been overrun by glacial ice in several hundred thousand years and is ideally located to receive glacigenic sediment. The Junín basin is underlain by carbonate rocks that have provided a source of Ca and HCO3 ions; precipitation of CaCO3 in the western margin of the lake during the present interglacial period has occurred at 1mm yr-1. An airgun seismic survey revealed a strong reflector at 105 meters depth, which marks the base of the lacustrine section. Drilling focused on three sites. Site 1, located near the depocenter and most distal to glacial sources, yielded a composite sediment thickness of 95m; Site 2, proximal to glacial outwash fans, yielded a composite thickness of 28 m; Site 3, located at an intermediate distance yielded a sediment thickness of 55m. The stratigraphy of Site 1 is marked by 8 glacial/interglacial cycles; the latter are characterized by low bulk density and magnetic susceptibility (MS) and high CaCO3. These units are intercalated with glacigenic sediment that has high density and MS, and low CaCO3. The age model for Site 1 is based on AMS radiocarbon dates on terrestrial macrofossils and dozens of U/Th ages on authigenic CaCO3. Strong and protracted interglacial periods appear to be associated with intervals of reduced variability of solar insolation in the Southern Hemisphere tropics. During these intervals there is strong covariation (r2>0.9) between the δ13C and δ18O of authigenic calcium carbonate, and δ18O values are relatively enriched (-12 to -2‰); examples include interglacial periods correlative with marine isotope stages (MIS) 1, 13, and 15. The magnitude of tropical glaciation appears to have been greater during glacial cycles prior to the LGM

  13. Rift Valley Fever.

    Science.gov (United States)

    Hartman, Amy

    2017-06-01

    Rift Valley fever (RVF) is a severe veterinary disease of livestock that also causes moderate to severe illness in people. The life cycle of RVF is complex and involves mosquitoes, livestock, people, and the environment. RVF virus is transmitted from either mosquitoes or farm animals to humans, but is generally not transmitted from person to person. People can develop different diseases after infection, including febrile illness, ocular disease, hemorrhagic fever, or encephalitis. There is a significant risk for emergence of RVF into new locations, which would affect human health and livestock industries. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Landform Evolution of the Zanskar Valley, Ladakh Himalaya.

    Science.gov (United States)

    Chahal, P.; Kumar, A.; Sharma, P.; Sundriyal, Y.; Srivastava, P.

    2017-12-01

    Zanskar River flow from south-west to north-east, perpendicularly through Higher Himalayan crystalline sequences, Tethyan sedimentary sequences, and Indus Molasses; and finally merge with the Indus River at Nimu. Geologically, the Indus valley is bounded by Ladakh Batholith in the north and highly folded and thrusted Zanskar mountain ranges in the south. Sedimentary sequences of Zanskar ranges are largely of continental origin, which were uplifted and deformed via several north verging thrusts, where Zanskar counter thrust, Choksti and Indus-Bazgo thrusts are important thrust zone, and there is atleast 36 km of crustal shortening in the Zanskar section which continued from middle Miocene to the late Pleistocene. This shortening is accommodated mainly by north or north-east directed Zanskar backthrusts. Two major tributaries of Zanskar: Tsrapchu and Doda, flow in the headwaters, along the strike of South Tibetan Detachment System (STDs), an east-west trending regional fault. The present study incorporate field sedimentology, geomorphology and chronology of landform associated with Zanskar valley. In the upper Zanskar, alluvial fan, valley fill and strath terraces configured the major landforms with paleo-lake deposits­­­ in the area between the fans. The lower catchment, at the confluence of Zanskar and Indus rivers, exhibit mainly valley fill terraces and strath terraces. Chronology suggests diachronous aggradation in the upper and lower Zanskar catchments. In the upper Zanskar large scale valley aggradation took place with simultaneously fan progradation and flooding events from 45-15 ka. Luminescence chronology of the lower Zanskar indicates aggradation from 145-55 ka and 18-12 ka. The two aggradation basins are separated by a deep V-shaped gorge which is approximately 60 km long. The longitudinal profile of the Zanskar River shows several local convexities marking knick point zone, which suggests tectonically controlled topography.

  15. Glacial lakes of the Central and Patagonian Andes

    Science.gov (United States)

    Wilson, Ryan; Glasser, Neil F.; Reynolds, John M.; Harrison, Stephan; Anacona, Pablo Iribarren; Schaefer, Marius; Shannon, Sarah

    2018-03-01

    The prevalence and increased frequency of high-magnitude Glacial Lake Outburst Floods (GLOFs) in the Chilean and Argentinean Andes suggests this region will be prone to similar events in the future as glaciers continue to retreat and thin under a warming climate. Despite this situation, monitoring of glacial lake development in this region has been limited, with past investigations only covering relatively small regions of Patagonia. This study presents new glacial lake inventories for 1986, 2000 and 2016, covering the Central Andes, Northern Patagonia and Southern Patagonia. Our aim was to characterise the physical attributes, spatial distribution and temporal development of glacial lakes in these three sub-regions using Landsat satellite imagery and image datasets available in Google Earth and Bing Maps. Glacial lake water volume was also estimated using an empirical area-volume scaling approach. Results reveal that glacial lakes across the study area have increased in number (43%) and areal extent (7%) between 1986 and 2016. Such changes equate to a glacial lake water volume increase of 65 km3 during the 30-year observation period. However, glacial lake growth and emergence was shown to vary sub-regionally according to localised topography, meteorology, climate change, rate of glacier change and the availability of low gradient ice areas. These and other factors are likely to influence the occurrence of GLOFs in the future. This analysis represents the first large-scale census of glacial lakes in Chile and Argentina and will allow for a better understanding of lake development in this region, as well as, providing a basis for future GLOF risk assessments.

  16. Aburra Valley: Quo vadis?

    International Nuclear Information System (INIS)

    Hermelin, Michel

    2008-01-01

    These paper intents a brief description of the evolution that characterised natural risk prevention in the area surrounding the city of Medellin, Colombia, called the Aburra Valley. Both the lithological and structural composition of the Valle and its topographic and climatic conditions contribute to the abundance of destructive natural phenomena as earthquakes, slope movements, flash floods and, in a lower proportion, to floods. The population increase, which reaches now 3.5 millions inhabitants and the frequent occupation of sites exposed to natural hazards have resulted in numerous disasters. At present two entities called SIMPAD and DAPARD work on risk prevention, on city and department scale respectively. The amount of knowledge about physical environment is considered to be insufficient, together with regulations which should direct land use in accordance to restrictions related to natural hazards. Several seminars on this topic have already been carried out and the organisers of the present one, destined to commemorate the twentieth anniversary of the Villatina disaster, should make the decision to meet each two years. Furthermore, the creation of a permanent commission dedicated to study past events, to foster information broadcasting and to seek a better knowledge of the Aburra Valley, should be considered

  17. Geomorphic and erosion studies at the Western New York Nuclear Service Center, West Valley, New York

    International Nuclear Information System (INIS)

    Boothroyd, J.C.; Timson, B.S.; Dana, R.H. Jr.

    1979-12-01

    This report is one in a series of related reports presenting the results of a study to evaluate the containment capability of a low-level, solid radioactive waste-burial ground at West valley, NY. This project is the first portion of a detailed geomorphic and erosion study of the reach of Buttermilk Creek adjacent to the waste-burial site. Buttermilk Creek valley is being actively modified by fluvial transport, lateral channel scour, and landsliding. High surface runoff rates create highly variable but enhanced stream flows that result in coarse-gravel sediment transport within the active channel. The active channel morphology indicates that braided stream processes are common in Buttermilk, leading to active channel down-cutting and lateral migration. Where lateral migration of the active channel has undercut valley wall slopes, large-scale landsliding enhances valley wall retreat. A major site of historical and recent slide activity lies adjacent to the low-level burial trenches. Initial, post-glacial Buttermilk Creek incision began before 9920 +- 240 B.P., the age of the oldest dated fluvial terrace. Future evolution of the system is expected to proceed by Buttermilk valley lowering, tributary and landslide widening, and stream capture

  18. Changes in Glaciers and Glacial Lakes and the Identification of Dangerous Glacial Lakes in the Pumqu River Basin, Xizang (Tibet

    Directory of Open Access Journals (Sweden)

    Tao Che

    2014-01-01

    Full Text Available Latest satellite images have been utilized to update the inventories of glaciers and glacial lakes in the Pumqu river basin, Xizang (Tibet, in the study. Compared to the inventories in 1970s, the areas of glaciers are reduced by 19.05% while the areas of glacial lakes are increased by 26.76%. The magnitudes of glacier retreat rate and glacial lake increase rate during the period of 2001–2013 are more significant than those for the period of the 1970s–2001. The accelerated changes in areas of the glaciers and glacial lakes, as well as the increasing temperature and rising variability of precipitation, have resulted in an increased risk of glacial lake outburst floods (GLOFs in the Pumqu river basin. Integrated criteria were established to identify potentially dangerous glacial lakes based on a bibliometric analysis method. It is found, in total, 19 glacial lakes were identified as dangerous. Such finding suggests that there is an immediate need to conduct field surveys not only to validate the findings, but also to acquire information for further use in order to assure the welfare of the humans.

  19. Timing of lake-level changes for a deep last-glacial Lake Missoula: optical dating of the Garden Gulch area, Montana, USA

    DEFF Research Database (Denmark)

    Smith, Larry N.; Sohbati, Reza; Buylaert, Jan-Pieter

    2018-01-01

    Glaciolacustrine sediments in the Clark Fork River valley at Garden Gulch, near Drummond, Montana, USA record highstand positions of the ice-dammed glacial Lake Missoula and repeated subaerial exposure. During these highstands the lake was at greater than 65% of its recognized maximum capacity......-level fluctuation, occurred over time scales of decades to ∼2 ka. Bioturbated sandy slopewash dated at 10.6 ± 0.9 ka and 11.9 ± 1.2 ka unconformably overlies the upper glaciolacustrine deposits. The uppermost sediments, above the glaciolacustrine section, are younger than the Glacier Peak tephra (13.7-13.4 cal ka B...... the lake's highstand position due to ice-dam failure likely led to scour in the downstream portions of the glacial Lake Missoula basin and megafloods in the Channeled Scabland....

  20. Abiotic landscape and vegetation patterns in the Netherlands during the Weichselian Late Glacial

    NARCIS (Netherlands)

    Hoek, W.Z.

    2000-01-01

    The Late Glacial landscape of the Netherlands was a landscape with changing geomorphology and vegetation. Glacial, eolian and fluvial processes in the time before the Late Glacial initially had formed the main landscape types that still existed during the Late Glacial. In these landscape types,

  1. A numerical solution to define channel heads and hillslope parameters from digital topography of glacially conditioned catchments

    Science.gov (United States)

    Salcher, Bernhard; Baumann, Sebastian; Kober, Florian; Robl, Jörg; Heiniger, Lukas

    2016-04-01

    region shows a distinct increase of mean elevation from the major overdeepend valleys near the Foreland to the alpine main divide at around 4000 m.a.s.l. within a distance of only 150 km. To define channel heads we first analyzed the variations to fine-scale topography of catchments by calculating the plan curvature at low topographic wavelengths. Higher elevated catchments more frequently impacted by glacial erosion show a higher degree in topographic flattening than catchments with a lower mean elevation where rougher fluvial (steady state) channels dominate. We found that this process of glacial destruction of fine-scale topography can well be analyzed by extracting the plan curvature from a DEM (1-30 m resolution). We furthermore found that the plan curvature frequency depends on the mean elevation of a catchment. Accordingly, the correlation between mean elevation of basins and the related density of pixels with a certain curvature is highly controlled by the used curvature threshold (e.g. used range of curvature pixels). A statistically derived optimum of the negative plan curvature was taken to define a threshold for the concavity of channels. The resulting fragmented network of channel segments was then fully integrated by utilizing a steepest descent algorithm. The upstream-most point of this fully integrated network was then defined as channel head. Our approach offers not only a consistent method to derive (i) hillslope and channel parameters in formerly glaciated catchments but also to (ii) measure the degree in glacial conditioning and therefore (iii) separating non-glacial from glacial catchments.

  2. Carbonate cementation in the late glacial outwash and beach deposits in northern Estonia

    Directory of Open Access Journals (Sweden)

    Maris Rattas

    2014-02-01

    Full Text Available The sedimentary environments, morphology and formation of carbonate cement in the late glacial glaciofluvial outwash and beach deposits in northern Estonia are discussed. Cementation is observed in well-drained, highly porous carbonaceous debris-rich gravel and sand-forming, resistant ledges in otherwise unconsolidated sediments. The cemented units occur as laterally continuous layers or as isolated lenticular patches with thicknesses from a few centimetres to 3 m. The cement is found in two main morphologies: (1 cement crusts or coatings around detrital grains and (2 massive cement almost entirely filling interparticle pores and intraparticle voids. It is exclusively composed of low-Mg calcite with angular equant to slightly elongated rhombohedral and scalenohedral or prismatic crystals, which indicate precipitation from meteoric or connate fresh surface (glacial lake water and/or near-surface groundwater under low to moderate supersaturation and flow conditions. The absence of organic structures within the cement suggests that cementation is essentially inorganic. The cement exhibits both meteoric vadose and phreatic features and most probably occurred close to the vadose–phreatic interface, where the conditions were transitional and/or fluctuating. Cementation has mainly taken place by CO2-degassing in response to fluctuations in groundwater level and flow conditions, controlled by the Baltic Ice Lake water level, and seasonal cold and/or dry climate conditions.

  3. Antireflectance coating on shielding window glasses using glacial acetic acid at ambient temperature

    International Nuclear Information System (INIS)

    Sathi Sasidharan, N.; Deshingkar, D.S.; Wattal, P.K.

    2006-01-01

    High density lead glasses having thickness of several centimeters and large dimensions are used as shielding windows in hot cells. To improve visibility, the reflection of light from its optically polished surfaces needs to be minimized to improve transmission as absorption of light in the thick glasses can not be avoided. Antireflectance coating of a material having low refractive index is required for this purpose. Selective leaching of lead at ambient temperature in glacial acetic acid develops a silica rich leached layer on glass surface. Since silica has low refractive index, the leached layer serves as antireflectance coating. Two optically polished discs of shielding window glasses were leached in glacial acetic acid at ambient temperature for 2, 5 and 10 days and their reflectance and transmittance spectra were taken to find effect of leaching. For transparent glass transmittance could be improved from 78.76% to 85.31% after 10 days leaching. Reflectance from the glass could be decreased from 12.48 to 11.67%. For coloured glass transmittance improved from 87.77% to 88.24% after 5 days leaching while reflectance decreased from 12.28% to 5.6% during same period. Based on data generated, 10 days leaching time is recommended for developing anti reflectance coating on transparent shielding window glass and 5 days for coloured shielding window glass. The procedure can be used for shielding windows of any dimensions by fabrication a PVC tank of slightly high dimensions and filling with acetic acid (author)

  4. Glacial cycles: exogenous orbital changes vs. endogenous climate dynamics

    Science.gov (United States)

    Kaufmann, R. K.; Juselius, K.

    2010-04-01

    We use a statistical model, the cointegrated vector autoregressive model, to assess the degree to which variations in Earth's orbit and endogenous climate dynamics can be used to simulate glacial cycles during the late Quaternary (390 kyr-present). To do so, we estimate models of varying complexity and compare the accuracy of their in-sample simulations. Results indicate that strong statistical associations between endogenous climate variables are not enough for statistical models to reproduce glacial cycles. Rather, changes in solar insolation associated with changes in Earth's orbit are needed to simulate glacial cycles accurately. Also, results suggest that non-linear dynamics, threshold effects, and/or free oscillations may not play an overriding role in glacial cycles.

  5. Inverse vertical migration and feeding in glacier lanternfish (Benthosema glaciale)

    KAUST Repository

    Dypvik, Eivind; Klevjer, Thor A.; Kaartvedt, Stein

    2011-01-01

    lanternfish (Benthosema glaciale) were mainly distributed below ~200 m and displayed three different diel behavioral strategies: normal diel vertical migration (NDVM), inverse DVM (IDVM) and no DVM (NoDVM). The IDVM group was the focus of this study

  6. Breakup of last glacial deep stratification in the South Pacific

    Science.gov (United States)

    Basak, Chandranath; Fröllje, Henning; Lamy, Frank; Gersonde, Rainer; Benz, Verena; Anderson, Robert F.; Molina-Kescher, Mario; Pahnke, Katharina

    2018-02-01

    Stratification of the deep Southern Ocean during the Last Glacial Maximum is thought to have facilitated carbon storage and subsequent release during the deglaciation as stratification broke down, contributing to atmospheric CO2 rise. Here, we present neodymium isotope evidence from deep to abyssal waters in the South Pacific that confirms stratification of the deepwater column during the Last Glacial Maximum. The results indicate a glacial northward expansion of Ross Sea Bottom Water and a Southern Hemisphere climate trigger for the deglacial breakup of deep stratification. It highlights the important role of abyssal waters in sustaining a deep glacial carbon reservoir and Southern Hemisphere climate change as a prerequisite for the destabilization of the water column and hence the deglacial release of sequestered CO2 through upwelling.

  7. QENS investigation of filled rubbers

    CERN Document Server

    Triolo, A; Desmedt, A; Pieper, J K; Lo Celso, F; Triolo, R; Negroni, F; Arrighi, V; Qian, H; Frick, B

    2002-01-01

    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface. (orig.)

  8. Gas-Filled Capillary Model

    International Nuclear Information System (INIS)

    Steinhauer, L. C.; Kimura, W. D.

    2006-01-01

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration -- Laser Wakefield (STELLA-LW) experiment

  9. Valley development on Hawaiian volcanoes

    International Nuclear Information System (INIS)

    Baker, V.R.; Gulick, V.C.

    1987-01-01

    Work in progress on Hawaiian drainage evolution indicates an important potential for understanding drainage development on Mars. Similar to Mars, the Hawaiian valleys were initiated by surface runoff, subsequently enlarged by groundwater sapping, and eventually stabilized as aquifers were depleted. Quantitative geomorphic measurements were used to evaluate the following factors in Hawaiian drainage evolution: climate, stream processes, and time. In comparing regions of similar climate, drainage density shows a general increase with the age of the volcani island. With age and climate held constant, sapping dominated valleys, in contrast to runoff-dominated valleys, display the following: lower drainage densities, higher ratios of valley floor width to valley height, and more positive profile concavities. Studies of stream junction angles indicate increasing junction angles with time on the drier leeward sides of the major islands. The quantitative geomorphic studies and earlier field work yielded important insights for Martian geomorphology. The importance of ash mantling in controlling infiltration on Hawaii also seems to apply to Mars. The Hawaiian valley also have implications for the valley networks of Martian heavily cratered terrains

  10. Glacial morphology and depositional sequences of the Antarctic Continental Shelf

    Science.gov (United States)

    ten Brink, Uri S.; Schneider, Christopher

    1995-01-01

    Proposes a simple model for the unusual depositional sequences and morphology of the Antarctic continental shelf. It considers the regional stratal geometry and the reversed morphology to be principally the results of time-integrated effects of glacial erosion and sedimentation related to the location of the ice grounding line. The model offers several guidelines for stratigraphic interpretation of the Antarctic shelf and a Northern Hemisphere shelf, both of which were subject to many glacial advances and retreats. -Authors

  11. Glacial ocean circulation and stratification explained by reduced atmospheric temperature

    OpenAIRE

    Jansen, Malte F.

    2016-01-01

    To understand climatic swings between glacial and interglacial climates we need to explain the observed fluctuations in atmospheric carbon dioxide (CO2), which in turn are most likely driven by changes in the deep ocean circulation. This study presents a model for differences in the deep ocean circulation between glacial and interglacial climates consistent with both our physical understanding and various proxy observations. The results suggest that observed changes in ocean circulation and s...

  12. 3D View of Death Valley, California

    Science.gov (United States)

    2000-01-01

    This 3-D perspective view looking north over Death Valley, California, was produced by draping ASTER nighttime thermal infrared data over topographic data from the US Geological Survey. The ASTER data were acquired April 7, 2000 with the multi-spectral thermal infrared channels, and cover an area of 60 by 80 km (37 by 50 miles). Bands 13, 12, and 10 are displayed in red, green and blue respectively. The data have been computer enhanced to exaggerate the color variations that highlight differences in types of surface materials. Salt deposits on the floor of Death Valley appear in shades of yellow, green, purple, and pink, indicating presence of carbonate, sulfate, and chloride minerals. The Panamint Mtns. to the west, and the Black Mtns. to the east, are made up of sedimentary limestones, sandstones, shales, and metamorphic rocks. The bright red areas are dominated by the mineral quartz, such as is found in sandstones; green areas are limestones. In the lower center part of the image is Badwater, the lowest point in North America.Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.The broad spectral coverage and high spectral resolution of ASTER will provide

  13. The glacial record of New Zealand's Southern Alps

    Science.gov (United States)

    Schaefer, J. M.; Denton, G.; Lowell, T.; Anderson, B.; Rinterknecht, V.; Schlosser, P.; Ivy-Ochs, S.; Kubik, P.; Schluechter, C.; Chinn, T.; Barrell, D.; Lifton, N.; Jull, T.

    2004-12-01

    We present detailed mapping and surface exposure dating using in-situ Be-10 and C-14 of the moraine set of Lake Pukaki, New Zealand's Southern Alps, spanning from the penultimate glaciation, over several Last Glacial Maximum (LGM) moraines, the late glacial event to Holocene glacial advances. New Zealand, a mountain ridge in the middle of the Southern Ocean, has one of the best preserved moraine records world-wide, offering the opportunity to reconstruct amplitude and timing of climate changes from Southern mid-latitudes, an area where paleoclimate data is scarce. The extensive mapping effort by G. Denton and colleagues (http://wyvern.gns.cri.nz/website/csigg/) provides a unique background for sample selection for Surface Exposure Dating. Our extensive data set (>40 samples analyzed so far) indicate that (i) the LGM in New Zealand terminated clearly prior to the Boelling/Alleroed warming, (ii) the late glacial advance is within uncertainties consistent with the timing of the Younger Dryas cold reversal; (iii) there occurred an early Holocene glacial event of the same amplitude than the Little Ice Age. This latter event is the first Holocene glacial event from the Southern Hemisphere dated by in-situ Be-10 and C-14.

  14. Potential for a significant deep basin geothermal system in Tintic Valley, Utah

    Science.gov (United States)

    Hardwick, C.; Kirby, S.

    2014-12-01

    The combination of regionally high heat flow, deep basins, and permeable reservoir rocks in the eastern Great Basin may yield substantial new geothermal resources. We explore a deep sedimentary basin geothermal prospect beneath Tintic Valley in central Utah using new 2D and 3D models coupled with existing estimates of heat flow, geothermometry, and shallow hydrologic data. Tintic Valley is a sediment-filled basin bounded to the east and west by bedrock mountain ranges where heat-flow values vary from 85 to over 240 mW/m2. Based on modeling of new and existing gravity data, a prominent 30 mGal low indicates basin fill thickness may exceed 2 km. The insulating effect of relatively low thermal conductivity basin fill in Tintic Valley, combined with typical Great Basin heat flow, predict temperatures greater than 150 °C at 3 km depth. The potential reservoir beneath the basin fill is comprised of Paleozoic carbonate and clastic rocks. The hydrology of the Tintic Valley is characterized by a shallow, cool groundwater system that recharges along the upper reaches of the basin and discharges along the valley axis and to a series of wells. The east mountain block is warm and dry, with groundwater levels just above the basin floor and temperatures >50 °C at depth. The west mountain block contains a shallow, cool meteoric groundwater system. Fluid temperatures over 50 °C are sufficient for direct-use applications, such as greenhouses and aquaculture, while temperatures exceeding 140°C are suitable for binary geothermal power plants. The geologic setting and regionally high heat flow in Tintic Valley suggest a geothermal resource capable of supporting direct-use geothermal applications and binary power production could be present.

  15. Filling of charged cylindrical capillaries

    NARCIS (Netherlands)

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J.C.T.; Tas, N.R.; Chakraborty, Suman; Mitra, Sushanta K.

    2014-01-01

    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because

  16. Space-filling polyhedral sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  17. Studies on the presence and spatial distribution of anthropogenic pollutants in the glacial basin of Scott Glacier in the face of climate change (Fiord Bellsund, Spitsbergen)

    Science.gov (United States)

    Lehmann, Sara; Kociuba, Waldemar; Franczak, Łukasz; Gajek, Grzegorz; Łeczyński, Leszek; Kozak, Katarzyna; Szopińska, Małgorzata; Ruman, Marek; Polkowska, Żaneta

    2014-10-01

    The study area covered the NW part of the Wedel Jarlsberg Land (SW part of the Svalbard Archipelago). The primary study object was the catchment of the Scott Glacier in the vicinity of the Research Station of of Maria Curie-Skłodowska University in Lublin - Calypsobyen. The Scott River catchment (of glacial hydrological regime) has an area of approximately 10 km2, 40% of which is occupied by the valley Scott Glacier in the phase of strong recession. The present study concerns the determination of physical and chemical parameters (pH, conductivity, TOC) and concentrations of pollutants (phenols, aldehydes).

  18. A 28,000 year history of vegetation and climate from Lower Red Rock Lake, Centennial Valley, Southwestern Montana, USA

    Science.gov (United States)

    Mumma, Stephanie Ann; Whitlock, Cathy; Pierce, Kenneth

    2012-01-01

    A sediment core extending to 28,000 cal yr BP from Lower Red Rock Lake in the Centennial Valley of southwestern Montana provides new information on the nature of full-glacial vegetation as well as a history of late-glacial and Holocene vegetation and climate in a poorly studied region. Prior to 17,000 cal yr BP, the eastern Centennial Valley was occupied by a large lake (Pleistocene Lake Centennial), and valley glaciers were present in adjacent mountain ranges. The lake lowered upon erosion of a newly formed western outlet in late-glacial time. High pollen percentages of Juniperus, Poaceae, Asteraceae, and other herbs as well as low pollen accumulation rates suggest sparse vegetation cover. Inferred cold dry conditions are consistent with a strengthened glacial anticyclone at this time. Between 17,000 and 10,500 cal yr BP, high Picea and Abies pollen percentages suggest a shift to subalpine parkland and warmer conditions than before. This is attributed to the northward shift of the jet stream and increasing summer insolation. From 10,500 to 7100 cal yr BP, pollen evidence of open dry forests suggests warm conditions, which were likely a response to increased summer insolation and a strengthened Pacific subtropical high-pressure system. From 7100 to 2400 cal yr BP, cooler moister conditions promoted closed forest and wetlands. Increases in Picea and Abies pollen percentages after 2400 cal yr BP suggest increasing effective moisture. The postglacial pattern of Pseudotsuga expansion indicates that it arrived later on the Atlantic side of the Continental Divide than on the Pacific side. The Divide may have been a physical barrier for refugial populations or it delimited different climate regions that influenced the timing of Pseudotsuga expansion.

  19. Remediating the South Alligator Valley uranium mining legacy

    International Nuclear Information System (INIS)

    Fawcett, M.; Waggitt, P.

    2010-01-01

    In late 1950s and early 1960s 13 uranium mines operated in the South Alligator Valley of Australia's Northern Territory. Once sales contracts had been filled the mines were abandoned and no remediation took place. In the 1980s the valley was designated as part of Stage 3 of the adjacent World Heritage-listed, Kakadu National Park. Proposals for remediation were only seriously put forward when the land was returned to the traditional Aboriginal owners, the Gunlom Land Trust, in 1996. Although they leased the land back so it would remain a part of Kakadu National Park the traditional Aboriginal owners required remediation to be complete by 2015. This paper tells the story of the development and implementation of the remediation process from the start of planning in 1998 to completion in 2009; and finally it describes the development of stakeholder relationships and the initial plans for long term stewardship. (author)

  20. Volcanic CO2 Emissions and Glacial Cycles: Coupled Oscillations

    Science.gov (United States)

    Burley, J. M.; Huybers, P. J.; Katz, R. F.

    2016-12-01

    Following the mid-Pleistocene transition, the dominant period of glacial cycles changed from 40 ka to 100 ka. It is broadly accepted that the 40 ka glacial cycles were driven by cyclical changes in obliquity. However, this forcing does not explain the 100 ka glacial cycles. Mechanisms proposed for 100 ka cycles include isostatic bed depression and proglacial lakes destabilising the Laurentide ice sheet, non-linear responses to orbital eccentricity, and Antarctic ice sheets influencing deep-ocean stratification. None of these are universally accepted. Here we investigate the hypothesis that variations in volcanic CO2 emissions can cause 100 ka glacial cycles. Any proposed mechanism for 100 ka glacial cycles must give the Earth's climate system a memory of 10^4 - 10^5years. This timescale is difficult to achieve for surface processes, however it is possible for the solid Earth. Recent work suggests volcanic CO2 emissions change in response to glacial cycles [1] and that there could be a 50 ka delay in that response [2]. Such a lagged response could drive glacial cycles from 40 ka cycles to an integer multiple of the forcing period. Under what conditions could the climate system admit such a response? To address this, we use a simplified climate model modified from Huybers and Tziperman [3]. Our version comprises three component models for energy balance, ice sheet growth and atmospheric CO2 concentration. The model is driven by insolation alone with other components varying according to a system of coupled, differential equations. The model is run for 500 ka to produce several glacial cycles and the resulting changes in global ice volume and atmospheric CO2 concentration.We obtain a switch from 40 ka to 100 ka cycles as the volcanic CO2 response to glacial cycles is increased. These 100 ka cycles are phase-locked to obliquity, lasting 80 or 120 ka. Whilst the MOR response required (in this model) is larger than plausible estimates based on [2], it illustrates the

  1. The Drentsche Aa valley system

    International Nuclear Information System (INIS)

    Gans, W. de.

    1981-01-01

    This thesis is composed of five papers concerned with Late Quaternary geology and geomorphology of the Aa valley system. The correlation and chronostratigraphic position of the layers have been established by radiocarbon dating. (Auth.)

  2. Late Proterozoic glacially controlled shelf sequences in western Mali (west Africa)

    Science.gov (United States)

    Deynoux, M.; Prousti, J. N.; Simon, B.

    The Late Proterozoic deposits of the Bakoye Group (500 m) in western Mali constitute a remarkable example of a glacially influenced sedimentary record on an epicratonic platform. They are composed of alternating marine and continental formations which represent accumulation in a basin located in the vicinity of upland areas covered by ice sheets. One of these formations (the Ba4 Formation), which is the focus of this study, is composed of three major units. The basal Unit 1 is made up of carbonaceous coarse to fine grained sandstones which are organized in fining upward sequences and which comprise lenticular diamictite intercalations. This Unit is considered to represent the fore slope gravity flows of a subaqueous ice-cootact fan fed by meltwater streams (≪glacioturbidites≫). Unit 2 is made up of coarse to fine grained sandstones in a highly variable association of facies. This Unit is characterized by the abundance of wave ripples associated with convolute beddings. planar or wavy beddings and tabular or hummocky crossbeddings in a general shallowing upward trend. It also comprises evidence of gravity processes including debris flows and large slumped sandstone bodies. Unit 2 represents the progressive filling of the Ba4 basin and reflects the combined effect of glacially induced eustatism and isostacy during a phase of glacial retreat. The basal part of Unit 3 is made up of a succession (a few meters thick) of conglomerates, diamictites, sandstones, siltstones or carbonates lying on an erosional unconformity marked by periglacial frost wedges. The upper part of Unit 3 is thicker (100-150 m) and onlaps on these basal facies with a succession of sandstone bars exhibiting swaley and hummocky crossbeddings, large cut and fill structures, and planar laminations. Unit 3 is strongly transgressive, the lower shoreface and backshore deposits include algal mats and are onlapped by sand ridges emplaced in a high energy upper to middle shoreface environment. Overall

  3. Methane Hydrate Formation from Enhanced Organic Carbon Burial During Glacial Lowstands: Examples from the Gulf of Mexico

    Science.gov (United States)

    Malinverno, A.; Cook, A.; Daigle, H.; Oryan, B.

    2017-12-01

    Methane hydrates in fine-grained marine sediments are often found within veins and fractures occupying discrete depth intervals that are surrounded by hydrate-free sediments. As they are not connected with gas sources beneath the base of the methane hydrate stability zone (MHSZ), these isolated hydrate-bearing intervals have been interpreted as formed by in situ microbial methane. We investigate here the hypothesis that these hydrate deposits form in sediments that were deposited during glacial lowstands and contain higher amounts of labile particulate organic carbon (POC), leading to enhanced microbial methanogenesis. During Pleistocene lowstands, river loads are deposited near the steep top of the continental slope and turbidity currents transport organic-rich, fine-grained sediments to deep waters. Faster sedimentation rates during glacial periods result in better preservation of POC because of decreased exposure times to oxic conditions. The net result is that more labile POC enters the methanogenic zone and more methane is generated in these sediments. To test this hypothesis, we apply an advection-diffusion-reaction model with a time-dependent deposition of labile POC at the seafloor controlled by glacioeustatic sea level variations in the last 250 kyr. The model is run for parameters estimated at three sites drilled by the 2009 Gulf of Mexico Joint Industry Project: Walker Ridge in the Terrebonne Basin (WR313-G and WR313-H) and Green Canyon near the canyon embayment into the Sigsbee Escarpment (GC955-H). In the model, gas hydrate forms in sediments with higher labile POC content deposited during the glacial cycle between 230 and 130 kyr (marine isotope stages 6 and 7). The corresponding depth intervals in the three sites contain hydrates, as shown by high bulk electrical resistivities and resistive subvertical fracture fills. This match supports the hypothesis that enhanced POC burial during glacial lowstands can result in hydrate formation from in situ

  4. Methane Hydrate Formation from Enhanced Organic Carbon Burial During Glacial Lowstands: Examples from the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Malinverno, Alberto; Cook, Ann; Daigle, Hugh; Oryan, Bar

    2017-12-15

    Methane hydrates in fine-grained marine sediments are often found within veins and fractures occupying discrete depth intervals that are surrounded by hydrate-free sediments. As they are not connected with gas sources beneath the base of the methane hydrate stability zone (MHSZ), these isolated hydrate-bearing intervals have been interpreted as formed by in situ microbial methane. We investigate here the hypothesis that these hydrate deposits form in sediments that were deposited during glacial lowstands and contain higher amounts of labile particulate organic carbon (POC), leading to enhanced microbial methanogenesis. During Pleistocene lowstands, river loads are deposited near the steep top of the continental slope and turbidity currents transport organic-rich, fine-grained sediments to deep waters. Faster sedimentation rates during glacial periods result in better preservation of POC because of decreased exposure times to oxic conditions. The net result is that more labile POC enters the methanogenic zone and more methane is generated in these sediments. To test this hypothesis, we apply an advection-diffusion-reaction model with a time-dependent deposition of labile POC at the seafloor controlled by glacioeustatic sea level variations in the last 250 kyr. The model is run for parameters estimated at three sites drilled by the 2009 Gulf of Mexico Joint Industry Project: Walker Ridge in the Terrebonne Basin (WR313-G and WR313-H) and Green Canyon near the canyon embayment into the Sigsbee Escarpment (GC955-H). In the model, gas hydrate forms in sediments with higher labile POC content deposited during the glacial cycle between 230 and 130 kyr (marine isotope stages 6 and 7). The corresponding depth intervals in the three sites contain hydrates, as shown by high bulk electrical resistivities and resistive subvertical fracture fills. This match supports the hypothesis that enhanced POC burial during glacial lowstands can result in hydrate formation from in situ

  5. Late Pleistocene glacial fluctuations in Cordillera Oriental, subtropical Andes

    Science.gov (United States)

    Martini, Mateo A.; Kaplan, Michael R.; Strelin, Jorge A.; Astini, Ricardo A.; Schaefer, Joerg M.; Caffee, Marc W.; Schwartz, Roseanne

    2017-09-01

    The behavior of subtropical glaciers during Middle to Late Pleistocene global glacial maxima and abrupt climate change events, specifically in Earth's most arid low-latitude regions, remains an outstanding problem in paleoclimatology. The present-day climate of Cordillera Oriental, in arid northwestern Argentina, is influenced by shifts in subtropical climate systems, including the South American Summer Monsoon. To understand better past glacier-subtropical climates during the global Last Glacial Maximum (LGM, 26.5-19 ka) and other time periods, we combined geomorphic features with forty-two precise 10Be ages on moraine boulders and reconstructed paleo-equilibrium line altitudes (ELA) at Nevado de Chañi (24°S) in the arid subtropical Andes. We found a major glacial expansion at ∼23 ± 1.6 ka, that is, during the global LGM. Additional glacial expansions are observed before the global LGM (at ∼52-39 ka), and after, at 15 ± 0.5 and 12 ± 0.6 ka. The ∼15 ka glacial event was found on both sides of Chañi and the ∼12 ka event is only recorded on the east side. Reconstructed ELAs of the former glaciers exhibit a rise from east to west that resembles the present subtropical climate trajectory from the Atlantic side of the continent; hence, we infer that this climate pattern must have been present in the past. Based on comparison with other low-latitude paleoclimate records, such as those from lakes and caves, we infer that both temperature and precipitation influenced past glacial occurrence in this sector of the arid Andes. Our findings also imply that abrupt deglacial climate events associated with the North Atlantic, specifically curtailed meridional overturning circulation and regional cooling, may have had attendant impacts on low subtropical Southern Hemisphere latitudes, including the climate systems that affect glacial activity around Nevado de Chañi.

  6. Hard-to-fill vacancies.

    Science.gov (United States)

    Williams, Ruth

    2010-09-29

    Skills for Health has launched a set of resources to help healthcare employers tackle hard-to-fill entry-level vacancies and provide sustainable employment for local unemployed people. The Sector Employability Toolkit aims to reduce recruitment and retention costs for entry-level posts and repare people for employment through pre-job training programmes, and support employers to develop local partnerships to gain access to wider pools of candidates and funding streams.

  7. Compilation of geologic, hydrologic, and ground-water flow modeling information for the Spokane Valley-Rathdrum Prairie aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

    Science.gov (United States)

    Kahle, Sue C.; Caldwell, Rodney R.; Bartolino, James R.

    2005-01-01

    The U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources and Washington Department of Ecology compiled and described geologic, hydrologic, and ground-water flow modeling information about the Spokane Valley-Rathdrum Prairie (SVRP) aquifer in northern Idaho and northeastern Washington. Descriptions of the hydrogeologic framework, water-budget components, ground- and surface-water interactions, computer flow models, and further data needs are provided. The SVRP aquifer, which covers about 370 square miles including the Rathdrum Prairie, Idaho and the Spokane valley and Hillyard Trough, Washington, was designated a Sole Source Aquifer by the U.S. Environmental Protection Agency in 1978. Continued growth, water management issues, and potential effects on water availability and water quality in the aquifer and in the Spokane and Little Spokane Rivers have illustrated the need to better understand and manage the region's water resources. The SVRP aquifer is composed of sand, gravel, cobbles, and boulders primarily deposited by a series of catastrophic glacial outburst floods from ancient Glacial Lake Missoula. The material deposited in this high-energy environment is coarser-grained than is typical for most basin-fill deposits, resulting in an unusually productive aquifer with well yields as high as 40,000 gallons per minute. In most places, the aquifer is bounded laterally by bedrock composed of granite, metasedimentary rocks, or basalt. The lower boundary of the aquifer is largely unknown except along the margins or in shallower parts of the aquifer where wells have penetrated its entire thickness and reached bedrock or silt and clay deposits. Based on surface geophysics, the thickness of the aquifer is about 500 ft near the Washington-Idaho state line, but more than 600 feet within the Rathdrum Prairie and more than 700 feet in the Hillyard trough based on drilling records. Depth to water in the aquifer is greatest in the northern

  8. Optimal tuning of a GCM using modern and glacial constraints

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, Lauren J.; Valdes, Paul J.; Payne, Antony J.; Kahana, Ron [University of Bristol, School of Geographical Sciences, Bristol (United Kingdom)

    2011-08-15

    In climate models, many parameters used to resolve subgrid scale processes can be adjusted through a tuning exercise to fit the model's output to target climatologies. We present an objective tuning of a low resolution Atmosphere-Ocean General Circulation Model (GCM) called FAMOUS where ten model parameters are varied together using a Latin hypercube sampling method to create an ensemble of 100 models. The target of the tuning consists of a wide range of modern climate diagnostics and also includes glacial tropical sea surface temperature. The ensemble of models created is compared to the target using an Arcsin Mielke score. We investigate how the tuning method used and the addition of glacial constraints impact on the present day and glacial climates of the chosen models. Rather than selecting a single configuration which optimises the metric in all the diagnostics, we obtain a subset of nine 'good' models which display great differences in their climate but which, in some sense, are all better than the original configuration. In those simulations, the global temperature response to last glacial maximum forcings is enhanced compared to the control simulation and the glacial Atlantic Ocean circulation is more in agreement with observations. Our study demonstrates that selecting a single 'optimal' configuration, relying only on present day constraints may lead to misrepresenting climates different to that of today. (orig.)

  9. Glacial ocean circulation and stratification explained by reduced atmospheric temperature.

    Science.gov (United States)

    Jansen, Malte F

    2017-01-03

    Earth's climate has undergone dramatic shifts between glacial and interglacial time periods, with high-latitude temperature changes on the order of 5-10 °C. These climatic shifts have been associated with major rearrangements in the deep ocean circulation and stratification, which have likely played an important role in the observed atmospheric carbon dioxide swings by affecting the partitioning of carbon between the atmosphere and the ocean. The mechanisms by which the deep ocean circulation changed, however, are still unclear and represent a major challenge to our understanding of glacial climates. This study shows that various inferred changes in the deep ocean circulation and stratification between glacial and interglacial climates can be interpreted as a direct consequence of atmospheric temperature differences. Colder atmospheric temperatures lead to increased sea ice cover and formation rate around Antarctica. The associated enhanced brine rejection leads to a strongly increased deep ocean stratification, consistent with high abyssal salinities inferred for the last glacial maximum. The increased stratification goes together with a weakening and shoaling of the interhemispheric overturning circulation, again consistent with proxy evidence for the last glacial. The shallower interhemispheric overturning circulation makes room for slowly moving water of Antarctic origin, which explains the observed middepth radiocarbon age maximum and may play an important role in ocean carbon storage.

  10. Catastrophic flooding origin of shelf valley systems in the English Channel.

    Science.gov (United States)

    Gupta, Sanjeev; Collier, Jenny S; Palmer-Felgate, Andy; Potter, Graeme

    2007-07-19

    Megaflood events involving sudden discharges of exceptionally large volumes of water are rare, but can significantly affect landscape evolution, continental-scale drainage patterns and climate change. It has been proposed that a significant flood event eroded a network of large ancient valleys on the floor of the English Channel-the narrow seaway between England and France. This hypothesis has remained untested through lack of direct evidence, and alternative non-catastrophist ideas have been entertained for valley formation. Here we analyse a new regional bathymetric map of part of the English Channel derived from high-resolution sonar data, which shows the morphology of the valley in unprecedented detail. We observe a large bedrock-floored valley that contains a distinct assemblage of landforms, including streamlined islands and longitudinal erosional grooves, which are indicative of large-scale subaerial erosion by high-magnitude water discharges. Our observations support the megaflood model, in which breaching of a rock dam at the Dover Strait instigated catastrophic drainage of a large pro-glacial lake in the southern North Sea basin. We suggest that megaflooding provides an explanation for the permanent isolation of Britain from mainland Europe during interglacial high-sea-level stands, and consequently for patterns of early human colonisation of Britain together with the large-scale reorganization of palaeodrainage in northwest Europe.

  11. A ~20,000 year history of glacial variability in the tropical Andes recorded in lake sediments from the Cordillera Blanca, Peru

    Science.gov (United States)

    Stansell, N.; Rodbell, D. T.; Moy, C. M.

    2010-12-01

    Pro-glacial lake sediments from the Cordillera Blanca, Peru contain continuous records of climate variability spanning the Last Glacial Maximum to present day. Here we present results from two alpine lake basins in the Queshgue Valley (9.8°S, 77.3°W) that contain high-resolution records of clastic sediment deposition for the last ~20,000 years. Radiocarbon-dated sediment cores were scanned at 0.5 to 1.0 cm resolution using a profiling x-ray fluorescence scanner for major and minor element distributions. In addition, we measured down-core variations in magnetic susceptibility, organic carbon, biogenic silica and calcium carbonate. Samples of bedrock and sediments from glacial moraines in the Queshgue watershed were analyzed using an ICP-MS in order to fingerprint and trace the source of glacial sediments deposited in the lakes. The bedrock is dominated by a combination of granodiorite with high Sr concentrations and meta-sedimentary rocks with high Zr values. Because the glacial sediments proximal to the modern glacier terminus are composed mostly of the granodiorite end-member, we interpret changes in Sr and clastic sediment concentrations in the lake sediment profiles as proxies for past glacial variability. Preliminary results indicate that glaciers retreated soon after ~14,500 cal yr BP and remained less extensive during the remaining late Glacial Stage and early Holocene. Gradually increasing clastic sediments through the middle and late Holocene indicate that glaciers became progressively larger, or more erosive towards present day. However, this overall Holocene trend of increasing glacier extent was interrupted by multiple periods of centennial- to millennial-scale ice margin retreat. For example, relative peaks in clastic sediments occurred from ~14,500 to 6000, 5600 to 5000, 4600 to 4200, 3600 to 3200, 2800 to 2700, 2400 to 2200, 1750 to 1550, 1100 to 900 cal yr BP, and during the Little Ice Age (~700 to 50 cal yr BP), while periods of low clastic

  12. Selection and specification criteria for fills for cut-and-fill mining

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, E. G.

    1980-05-15

    Because of significant differences in placement and loading conditions, the ideal fill material for a cut-and-fill operation has different characteristics to those for a fill for a filled open stoping operation. The differing requirements of the two mining operations must be understood and accounted for in establishing fill selection and specification criteria. Within the paper, aspects of the particular requirements of cut-and-fill mining are analyzed and related to the specific fill tests and properties required. Emphasis is placed upon the role of fill in ground support, though this cannot be isolated from overall fill performance. Where appropriate, test data are introduced and areas requiring continuing research highlighted.

  13. The high-level marine shell-bearing deposits of Clava, Inverness-shire, and their origin as glacial rafts

    Science.gov (United States)

    Merritt, J. W.

    The enigmatic high-level, till-covered, cold water marine shell-bearing deposits at Clava, Inverness-shire, are described systematically in the light of new observations made at sites documented in the literature. The marine deposits, named here as the Clava Shelly Formation, include three members, the unfossiliferous Clava sand, the underlying Clava shelly clay and a shelly diamicton known as the Clava shelly till. The first two members form a conformable coarsening-upwards sequence containing a shallow water, high-boreal to low-Arctic fauna and flora. The Clava shelly till is essentially glacially re-sedimented glaciomarine clay containing a sparse fauna, but its stratigraphic relationship and age are not absolutely clear. The shelly clay is ascribed to a Mid-Devensian interstadial episode on the basis of amino-acid dating. It is concluded that the Clava shelly clay, and several discrete masses of Clava sand and shelly till, are glacially transported allochthons derived from the Great Glen. The rafts were probably detached as a result of high pore water pressure building up in laterally restricted aquifers beneath a confined glacier that flowed north-eastwards across the Loch Ness basin. This glacier was deflected eastwards and upwards towards Clava by ice flowing from the northern Highlands along the Beauly Firth during the build-up of the last Scottish ice-sheet. The rafts were stacked at the ice margin when the glacier entered the Nairn Valley before being overriden by the expanding ice-sheet.

  14. Overdeepening development in a glacial landscape evolution model with quarrying

    DEFF Research Database (Denmark)

    Ugelvig, Sofie Vej; Egholm, D.L.; Iverson, Neal R.

    In glacial landscape evolution models, subglacial erosion rates are often related to basal sliding or ice discharge by a power-law. This relation can be justified when considering bed abrasion, where rock debris transported in the basal ice drives erosion. However, the relation is not well...... supported when considering models for quarrying of rock blocks from the bed. Field observations indicate that the principal mechanism of glacial erosion is quarrying, which emphasize the importance of a better way of implementing erosion by quarrying in glacial landscape evolution models. Iverson (2012...... around the obstacles. The erosion rate is quantified by considering the likelihood of rock fracturing on topographic bumps. The model includes a statistical treatment of the bedrock weakness, which is neglected in previous quarrying models. Sliding rate, effective pressure, and average bedslope...

  15. Unraveling Tropical Mountain Hydroclimatology by Coupling Autonomous Sensor Observations and Climate Modeling: Llanganuco Valley, Cordillera Blanca, Peru.

    Science.gov (United States)

    Hellstrom, R. A.; Fernandez, A.; Mark, B. G.; Covert, J. M.

    2015-12-01

    Northern Peru will face critical water resource issues in the near future as permanent ice retreats. Much of current global and regional climate research neglects the meteorological forcing of lapse rates and valley wind dynamics on critical components of the Peruvian Andes' water-cycle. In 2004 and 2005 we installed an autonomous sensor network (ASN) within the glacierized Llanganuco Valley, Cordillera Blanca (9°S), consisting of discrete, cost-effective, automatic temperature loggers located along the valley axis and anchored by two automatic weather stations. Comparisons of these embedded atmospheric measurements from the ASN and climate modeling (CM) by dynamical downscaling using the Weather Research and Forecasting (WRF) model elucidate distinct diurnal and seasonal characteristics of the mountain valley winds and lapse rates. Wind, temperature, humidity, and cloud simulations by WRF suggest that thermally driven valley winds converging with easterly flow aloft enhance late afternoon and evening cloud development which helps explain detected nocturnal precipitation maxima measured by the ASN. We attribute sustained evapotranspiration (ET), as estimated by the FAO-56 Penman-Monteith model, to an abundance of glacial melt-water during the dry season and strong pre-noon solar heating during the wet season. Furthermore, the extreme diurnal variability of along-valley-axis lapse rates and valley wind detected from ground observations and confirmed by dynamical downscaling demonstrate the importance of realistic scale parameterizations of the boundary layer to improve regional CM projections in mountainous regions. Our findings portray ET as an integral yet poorly represented process in Andean hydroclimatology. We show that coupling ASN and CM can improve understanding of multi-scale atmospheric and associated hydrological processes in mountain valleys.

  16. Technology of hardening fills for mined spaces

    International Nuclear Information System (INIS)

    Simek, P.; Holas, M.; Chyla, A.; Pech, P.

    1985-01-01

    The technology is described of hardening fills for mined spaces of uranium deposits in North Bohemian chalk. A special equipment was developed for the controlled preparation of a hardening mixture. The composition of the fill is determined by the strength of the filled rock, expecially by the standard strength, i.e., the minimal strength of the filling under uniaxial pressure. The said parameter determines the consumption of binding materials and thereby the total costs of the filling. A description is presented of the filling technology, including rabbit tube transport of the mixture and quality control. (Pu)

  17. Charge balancing fill rate monitor

    International Nuclear Information System (INIS)

    Rothman, J.L.; Blum, E.B.

    1995-01-01

    A fill rate monitor has been developed for the NSLS storage rings to allow machine tuning over a very large dynamic range of beam current. Synchrotron light, focused on a photodiode, produces a signal proportional to the beam current. A charge balancing circuit processes the diode current, creating an output signal proportional to the current injected into the ring. The unit operates linearly over a dynamic range of 120 dB and can resolve pulses of injected beam as small as 1 μA

  18. ESR Dating Research of Glacial Tills in Tibetan Plateau

    Science.gov (United States)

    Bi, W.; Yi, C.

    2016-12-01

    In recent years, Quaternary Glacial-chronology has been made remarkable progress in the Tibetan Platean(TP) with the development of several numeric dating techniques, such as cosmogenic nuclides(NC), optically stimulated luminescence(OSL) and 14C. In constrast, the dating of Quaternary glacial tills in 100,000 years even more than million-year has been a challenge, just because the techniques has defects themselves and the sediments were stransformed during the geological and geomorphology progress later. Electron Spin Resonance(ESR) has been becoming one of the key methods of Quaternary Glacial-chronology with wide range of dating, expecially for the sample older than 100,000 years up to million-year scale. The accurate measurement of equivalent dose significantly impacts on accuracy and reliability of ESR dating method. Therefore, the study of the mechanisms of resetting processes is fundamental for accurate and reliable ESR dating. To understand the mechanism and characteristics of quartz ESR signal resetting of different samples, a series of laboratory simulation and field observation studies were carried out, which made lots of important breakthrough. But the research in quartz ESR signal of moraines is less and the test of ESR dating method is still in the qualitative investigation. Therefor, we use ESR dating and study on the mechanism and characteristics of quartz ESR signals in tills in the Tibetan Platean. In the adjust method of Modern, the quartz ESR signals in Modern glacial tills represent residual values which can be adjusted signals in the older glacial tills. As a consequence, ESR dating of the quartz in moraines needs to be explored in deep with building models to adjust ages which are measured by ESR dating. Therefore, ESR dating will become the trusted one of the cross dating methods in Quaternary Glacial-chronology with the adjust mothod improving the accuracy of ESR dating ages.

  19. Glacial modification of granite tors in the Cairngorms, Scotland

    Science.gov (United States)

    Hall, A.M.; Phillips, W.M.

    2006-01-01

    A range of evidence indicates that many granite tors in the Cairngorms have been modified by the flow of glacier ice during the Pleistocene. Comparisons with SW England and the use of a space-time transformation across 38 tor groups in the Cairngorms allow a model to be developed for progressive glacial modification. Tors with deeply etched surfaces and no, or limited, block removal imply an absence of significant glacial modification. The removal of superstructure and blocks, locally forming boulder trains, and the progressive reduction of tors to stumps and basal slabs represent the more advanced stages of modification. Recognition of some slabs as tor stumps from which glacial erosion has removed all superstructure allows the original distribution of tors to be reconstructed for large areas of the Cairngorms. Unmodified tors require covers of non-erosive, cold-based ice during all of the cold stages of the Middle and Late Pleistocene. Deformation beneath cold-based glacier ice is capable of the removal of blocks but advanced glacial modification requires former wet-based glacier ice. The depth of glacial erosion at former tor sites remains limited largely to the partial or total elimination of the upstanding tor form. Cosmogenic nuclide exposure ages (Phillips et al., 2006) together with data from weathering pit depths (Hall and Phillips, 2006), from the surfaces of tors and large erratic blocks require that the glacial entrainment of blocks from tors occurred in Marine Isotope Stages (MIS) 4-2, 6 and, probably, at least one earlier phase. The occurrence of glacially modified tors on or close to, the main summits of the Cairngorms requires full ice cover over the mountains during these Stages. Evidence from the Cairngorms indicates that tor morphology can be regarded as an important indicator of former ice cover in many formerly glaciated areas, particularly where other evidence of ice cover is sparse. Recognition of the glacial modification of tors is important

  20. Glacial Fluctuation in the Source Region of the Yangtze River

    International Nuclear Information System (INIS)

    Shengyi, Gao; Qingsong, Fan; Xi, Cao; Li, Ma

    2014-01-01

    Glaciers in the source region of the Yangtze River are not only water resources but also important energy and environmental resources. Glacial fluctuation is an important component of the study of changes in the natural environment, including climate change. We investigated the glaciers in the source region of the Yangtze River, and analyzed the fluctuations using multi-temporal remote sensing data. The trend in glacial fluctuation and the factors that influence it were determined. The results have implications for water resource management and environmental conservation in the Yangtze River region

  1. Late-Glacial radiocarbon- and palynostratigraphy in the Swiss Plateau

    International Nuclear Information System (INIS)

    Ammann, B.; Lotter, A.F.

    1989-01-01

    A detailed Late-Glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator 14 C dates on terrestrial plant macrofossils. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Boelling and the Younger Dryas becomes obvious. 54 refs

  2. Glacial Meltwater Contirbutions to the Bow River, Alberta, Canada

    Science.gov (United States)

    Bash, E. A.; Marshall, S. J.; White, E. C.

    2009-12-01

    Assessment of glacial melt is critical for water resource management in areas which rely on glacier-fed rivers for agricultural and municipal uses. Changes in precipitation patterns coupled with current glacial retreat are altering the glacial contribution to river flow in areas such as the Andes of South America and the high ranges of Asia, as well as the Rockies of Western Canada. Alberta’s Bow River has its headwaters in the eastern slopes of the Canadian Rockies and contributes to the Nelson drainage system feeding into Hudson Bay. The Bow River basin contains several population centers, including the City of Calgary, and is heavily taxed for agricultural use. The combined effects of rapid glacial retreat in the Canadian Rockies, higher drought frequency, and increased demand are likely to heighten water stress in Southern Alberta. However, there has been little focus to date on the extent and importance of glacial meltwater in the Bow River. The Bow River contains 74.5 km2 of glacier ice, which amounts to only 0.29% of the basin. While this number is not high compared to some glacierized areas, Hopkinson and Young (1998) report that in dry years, glacier melt can provide up to 50% of late summer flows at a station in the upper reaches of the river system. We extend this work with an assessment of monthly and annual glacial contributions to the Bow River farther downstream in Calgary. Our analysis is based on mass balance, meteorological, and hydrological data that has been collected at the Haig Glacier since 2001. This data is used in conjunction with glacier coverage and hypsometric data for the remainder of the basin to estimate seasonal snow and glacial meltwater contributions to the Bow River from the glacierized fraction of the catchment. The results of this study show the percentage of total flow attributed to glacial melt to be highly variable. Glacier runoff contributes up to an order of magnitude more water to the Bow River per unit area of

  3. A model of late quaternary landscape development in the Delaware Valley, New Jersey and Pennsylvania

    Science.gov (United States)

    Ridge, J.C.; Evenson, E.B.; Sevon, W.D.

    1992-01-01

    In the Delaware Valley of New Jersey and eastern Pennsylvania the late Quaternary history of colluviation, fluvial adjustment, and soil formation is based on the ages of pre-Wisconsinan soils and glacial deposits which are indicated by feld relationships and inferred from mid-latitude climate changes indicated by marine oxygen-isotope records. The area is divided into four terranes characterized by sandstone, gneiss, slate and carbonate rocks. Since the last pre-Wisconsinan glaciation (> 130 ka, inferred to be late Illinoian), each terrane responded differently to chemical and mechanical weathering. During the Sangamon interglacial stage (??? 130-75 ka) in situ weathering is inferred to have occurred at rates greater than transportation of material which resulted in the formation of deep, highly weathered soil and saprolite, and dissolution of carbonate rocks. Cold climatic conditions during the Wisconsinan, on the other hand, induced erosion of the landscape at rates faster than soil development. Upland erosion during the Wisconsinan removed pre-Wisconsinan soil and glacial sediment and bedrock to produce muddy to blocky colluvium, gre??zes lite??es, and alluvial fans on footslopes. Fluvial gravel and overlying colluvium in the Delaware Valley, both buried by late Wisconsinan outwash, are inferred to represent episodes of early and middle Wisconsinan (??? 75-25 ka) upland erosion and river aggradiation followed by river degradation and colluvium deposition. Early-middle Wisconsinan colluvium is more voluminous than later colluvium despite colder, possibly permafrost conditions during the late Wisconsinan ??? 25-10 ka). Extensive colluviation during the early and middle Wisconsinan resulted from a longer (50 kyr), generally cold interval of erosion with a greater availability of easily eroded pre-Wisconsinan surficial materials on uplands than during the late Wisconsinan. After recession of late Wisconsinan ice from its terminal position, soil formation and

  4. Budgets and chemical characterization of groundwater for the Diamond Valley flow system, central Nevada, 2011–12

    Science.gov (United States)

    Berger, David L.; Mayers, C. Justin; Garcia, C. Amanda; Buto, Susan G.; Huntington, Jena M.

    2016-07-29

    The Diamond Valley flow system consists of six hydraulically connected hydrographic areas in central Nevada. The general down-gradient order of the areas are southern and northern Monitor Valleys, Antelope Valley, Kobeh Valley, Stevens Basin, and Diamond Valley. Groundwater flow in the Diamond Valley flow system terminates at a large playa in the northern part of Diamond Valley. Concerns relating to continued water-resources development of the flow system resulted in a phased hydrologic investigation that began in 2005 by the U.S. Geological Survey in cooperation with Eureka County. This report presents the culmination of the phased investigation to increase understanding of the groundwater resources of the basin-fill aquifers in the Diamond Valley flow system through evaluations of groundwater chemistry and budgets. Groundwater chemistry was characterized using major ions and stable isotopes from groundwater and precipitation samples. Groundwater budgets accounted for all inflows, outflows, and changes in storage, and were developed for pre-development (pre-1950) and recent (average annual 2011–12) conditions. Major budget components include groundwater discharge by evapotranspiration and groundwater withdrawals; groundwater recharge by precipitation, and interbasin flow; and storage change.

  5. Geomorphological characteristics of increased landslide activity in the Gudbrandsdalen valley, Norway

    Science.gov (United States)

    Heyerdahl, Håkon; Høydal, Øyvind

    2016-04-01

    The Gudbrandsdalen valley in Eastern Norway lies in a region where annual precipitation is generally low (down to 300 mm/year). The landslide activity has consequently historically been low, although the lower part of the valley sides generally is draped with thick layers of Quaternary deposits, primarily of glacial or glaciofluvial origin. The perception of natural hazards in the valley was previously primarily connected to flooding in the main river in the valley bottom during early summer, due to large discharges resulting from snowmelt in the mountainous regions west and east of the valley. However, several high-intensity events have changed the image of the region. Starting with a localized, but intense, landslide event in the Northern part of the valley in year 2008, two larger events covering almost the entire valley occurred in the years 2011 and 2013. A high number of landslides was triggered in all these events, including many flash floods and debris flows/debris slides in small and steep tributary rivers along the valley slopes. Landslide triggering covers different release mechanisms: In 2008, landslides were triggered without precipitation in not-frozen soil deposits without snow cover in the lower part of the valley. Groundwater flow through the permeable bedrock ("Otta schist") resulting from snow-melt in the elevated mountainous areas caused landslide triggering due to positive pore-water pressures forming at the bedrock surface below soil deposits, or at depressions in the terrain. Subsequent rainfall resulted in even more landslides being released. In later events (years 2011 and 2013) many landslides were caused by surface water taking new paths downslope, often due to man-made changes in existing waterways (typically poorly planned drainage solutions or new roads). Relatively small discharges in slopes with unconsolidated and easily erodible glacial deposits (typically lateral moraine) in many cases lead to small initial slides that down

  6. Evidence of volcanic and glacial activity in Chryse and Acidalia Planitiae, Mars

    Science.gov (United States)

    Martinez-Alonso, Sara; Mellon, Michael T.; Banks, Maria E.; Keszthelyi, Laszlo P.; McEwen, Alfred S.

    2011-01-01

    Chryse and Acidalia Planitiae show numerous examples of enigmatic landforms previously interpreted to have been influenced by a water/ice-rich geologic history. These landforms include giant polygons bounded by kilometer-scale arcuate troughs, bright pitted mounds, and mesa-like features. To investigate the significance of the last we have analyzed in detail the region between 60°N, 290°E and 10°N, 360°E utilizing HiRISE (High Resolution Imaging Science Experiment) images as well as regional-scale data for context. The mesas may be analogous to terrestrial tuyas (emergent sub-ice volcanoes), although definitive proof has not been identified. We also report on a blocky unit and associated landforms (drumlins, eskers, inverted valleys, kettle holes) consistent with ice-emplaced volcanic or volcano-sedimentary flows. The spatial association between tuya-like mesas, ice-emplaced flows, and further possible evidence of volcanism (deflated flow fronts, volcanic vents, columnar jointing, rootless cones), and an extensive fluid-rich substratum (giant polygons, bright mounds, rampart craters), allows for the possibility of glaciovolcanic activity in the region.Landforms indicative of glacial activity on Chryse/Acidalia suggest a paleoclimatic environment remarkably different from today's. Climate changes on Mars (driven by orbital/obliquity changes) or giant outflow channel activity could have resulted in ice-sheet-related landforms far from the current polar caps.

  7. The hydrochemistry of glacial Ebba River (Petunia Bay, Central Spitsbergen): Groundwater influence on surface water chemistry

    Science.gov (United States)

    Dragon, Krzysztof; Marciniak, Marek; Szpikowski, Józef; Szpikowska, Grażyna; Wawrzyniak, Tomasz

    2015-10-01

    The article presents the investigation of surface water chemistry changes of the glacial Ebba River (Central Spitsbergen) during three melting seasons of 2008, 2009 and 2010. The twice daily water chemistry analyses allow recognition of the surface water chemistry differentiation. The surface water chemistry changes are related to the river discharge and changes in the influence of different water balance components during each melting season. One of the most important process that influence river water component concentration increase is groundwater inflow from active layer occurring on the valley area. The significance of this process is the most important at the end of the melting season when temperatures below 0 °C occur on glaciers (resulting in a slowdown of melting of ice and snow and a smaller recharge of the river by the water from the glaciers) while the flow of groundwater is still active, causing a relatively higher contribution of groundwater to the total river discharge. The findings presented in this paper show that groundwater contribution to the total polar river water balance is more important than previously thought and its recognition allow a better understanding of the hydrological processes occurring in a polar environment.

  8. Moraine preservation and boulder erosion in the tropical Andes: interpreting old surface exposure ages in glaciated valleys

    Science.gov (United States)

    Smith, Jacqueline A.; Finkel, Robert C.; Farber, Daniel L.; Rodbell, Donald T.; Seltzer, Geoffrey O.

    2005-10-01

    Cosmogenic dating provides a long-awaited means of directly dating glacial deposits that pre-date the last glacial cycle. Although the potential benefits of longer chronologies are obvious, the greater uncertainty associated with older cosmogenic ages may be less readily apparent. We illustrate the challenges of developing and interpreting a long chronology using our data from the Peruvian Andes. We used surface exposure dating with cosmogenic radionuclides (CRNs; 10Be and 26Al) to date 140 boulders on moraines in valleys bordering the Junin Plain (11° S, 76° W) in central Peru. Our chronology spans multiple glacial cycles and includes exposure ages greater than 1 million years, which indicate that long-term rates of boulder erosion have been very low. Interpreting the chronology of moraines for glaciations that predate the last glacial cycle is complicated by the need to consider boulder erosion and exhumation, surface uplift, and inheritance of CRNs from previous exposure intervals. As an example, we recalculate exposure ages using our boulder erosion rates (0.3-0.5 metres per million years) and estimated surface uplift rates to emphasise both the challenges involved in interpreting old surface exposure ages and the value of chronological data, even with large uncertainties, when reconstructing the palaeoclimate of a region.

  9. Bio-inspired dental fillings

    Science.gov (United States)

    Deyhle, Hans; Bunk, Oliver; Buser, Stefan; Krastl, Gabriel; Zitzmann, Nicola U.; Ilgenstein, Bernd; Beckmann, Felix; Pfeiffer, Franz; Weiger, Roland; Müller, Bert

    2009-08-01

    Human teeth are anisotropic composites. Dentin as the core material of the tooth consists of nanometer-sized calcium phosphate crystallites embedded in collagen fiber networks. It shows its anisotropy on the micrometer scale by its well-oriented microtubules. The detailed three-dimensional nanostructure of the hard tissues namely dentin and enamel, however, is not understood, although numerous studies on the anisotropic mechanical properties have been performed and evaluated to explain the tooth function including the enamel-dentin junction acting as effective crack barrier. Small angle X-ray scattering (SAXS) with a spatial resolution in the 10 μm range allows determining the size and orientation of the constituents on the nanometer scale with reasonable precision. So far, only some dental materials, i.e. the fiber reinforced posts exhibit anisotropic properties related to the micrometer-size glass fibers. Dental fillings, composed of nanostructures oriented similar to the natural hard tissues of teeth, however, do not exist at all. The current X-ray-based investigations of extracted human teeth provide evidence for oriented micro- and nanostructures in dentin and enamel. These fundamental quantitative findings result in profound knowledge to develop biologically inspired dental fillings with superior resistance to thermal and mechanical shocks.

  10. Late Quaternary pollen records from the Lower Cobb Valley and adjacent areas, north-west Nelson, New Zealand

    International Nuclear Information System (INIS)

    Shulmeister, J.; McLea, W.L.; Singer, C.; McKay, R.M.; Hosie, C.

    2003-01-01

    Ten pollen records from the Cobb Valley and adjacent areas in North-West Nelson are described. Collectively they provide a vegetation record extending from the Last Glacial Maximum to the present day. During the Last Glacial Maximum the uplands of North-West Nelson were glaciated. By about 17,000 radiocarbon years BP ice had retreated some distance up the Cobb River Valley and a podocarp heath and tussockland vegetation covered non-glaciated areas. By 14,000 radiocarbon years BP, the valley floor and adjacent lower ridges were occupied by montane podocarp forest dominated by Phyllocladus and Halocarpus. Beech forest expanded into some sites as early as 13,000 yr BP but the modern beech cover was not established until the Holocene. Forest cover has fluctuated in response to disturbance over the Holocene, but the most significant recent change, which is related to clearing for pastoralism in the last two centuries, has had surprisingly little impact on the pollen records. (author). 40 refs., 11 figs., 1 tab

  11. Hydrogeologic implications of increased septic-tank-soil-absorption system density, Ogden Valley, Weber County, Utah

    Science.gov (United States)

    Lowe, Mike; Miner, Michael L.; ,

    1990-01-01

    Ground water in Ogden Valley occurs in perched, confined, and unconfined aquifers in the valley fill to depths of 600 feet and more. The confined aquifer, which underlies only the western portion of the valley, is overlain by cleyey silt lacustrine sediments probably deposited during the Bonneville Basin's Little Valley lake cycle sometime between 90,000 and 150,000 years ago. The top of this cleyey silt confining layer is generally 25 to 60 feet below the ground surface. Unconfined conditions occur above and beyond the outer margin of the confining layer. The sediments overlying the confining layer are primarily Lake Bonneville deposits. Water samples from springs, streams, and wells around Pineview Reservoir, and from the reservoir itself, were collected and analyzed. These samples indicate that water quality in Ogden Valley is presently good. Average nitrate concentrations in the shallow unconfined aquifer increase toward the center of Ogden Valley. This trend was not observed in the confined aquifer. There is no evidence, however, of significant water-quality deterioration, even in the vicinity of Huntsville, a town that has been densely developed using septic-tank-soil-absorption systems for much of the time since it was founded in 1860.

  12. Vertical Scan-Conversion for Filling Purposes

    OpenAIRE

    Hersch, R. D.

    1988-01-01

    Conventional scan-conversion algorithms were developed independently of filling algorithms. They cause many problems, when used for filling purposes. However, today's raster printers and plotters require extended use of filling, especially for the generation of typographic characters and graphic line art. A new scan-conversion algorithm, called vertical scan-conversion has been specifically designed to meet the requirements of parity scan line fill algorithms. Vertical scan-conversion ensures...

  13. Geophysical Surveys of the Hydrologic Basin Underlying Yosemite Valley, California.

    Science.gov (United States)

    Maher, E. L.; Shaw, K. A.; Carey, C.; Dunn, M. E.; Whitman, S.; Bourdeau, J.; Eckert, E.; Louie, J. N.; Stock, G. M.

    2017-12-01

    UNR students in an Applied Geophysics course conducted geophysical investigations in Yosemite Valley during the months of March and August 2017. The goal of the study is to understand better the depth to bedrock, the geometry of the bedrock basin, and the properties of stratigraphy- below the valley floor. Gutenberg and others published the only prior geophysical investigation in 1956, to constrain the depth to bedrock. We employed gravity, resistivity, and refraction microtremor(ReMi) methods to investigate the interface between valley fill and bedrock, as well as shallow contrasts. Resistivity and ReMi arrays along three north-south transects investigated the top 50-60m of the basin fill. Gravity results constrained by shallow measurements suggest a maximum depth of 1000 m to bedrock. ReMi and resistivity techniques identified shallow contrasts in shear velocity and electrical resistivity that yielded information about the location of the unconfined water table, the thickness of the soil zone, and spatial variation in shallow sediment composition. The upper several meters of sediment commonly showed shear velocities below 200 m/s, while biomass-rich areas and sandy river banks could be below 150 m/s. Vs30 values consistently increased towards the edge of the basin. The general pattern for resistivity profiles was a zone of relatively high resistivity, >100 ohm-m, in the top 4 meters, followed by one or more layers with decreased resistivity. According to gravity measurements, assuming either -0.5 g/cc or -0.7 g/cc density contrast between bedrock and basin sediments, a maximum depth to bedrock is found south of El Capitan at respectively, 1145 ± 215 m or 818 ± 150 m. Longitudinal basin geometry coincides with the basin depth geometry discussed by Gutenberg in 1956. Their results describe a "double camel" shape where the deepest points are near El Capitan and the Ahwahnee Hotel and is shallowest near Yosemite Falls, in a wider part of the valley. An August Deep

  14. An Embedded Sensor Network for Measuring Elevation Effects on Temperature, Humidity, and Evapotranspiration Within a Tropical Alpine Valley

    Science.gov (United States)

    Hellstrom, R. A.; Mark, B. G.

    2006-12-01

    Conditions of glacier recession in the seasonally dry tropical Peruvian Andes motivates research to better constrain the hydrological balance in alpine valleys. Studies suggest that glaciers in the tropical Andes are particularly sensitive to seasonal humidity flux due to the migration of the Intertropical Convergence Zone. However, there is an outstanding need to better measure and model the spatiotemporal variability of energy and water budgets within pro-glacial valleys. In this context, we introduce a novel embedded network of low- cost, discrete temperature and humidity microloggers and an automatic weather station installed in the Llanganuco valley of the Cordillera Blanca. This paper presents data recorded over a full annual cycle (2004- 2005) and reports on network design and results during the dry and wet seasons. The transect of sensors ranging from about 3500 to 4700 m reveal seasonally characteristic diurnal fluctuations in up-valley lapse rate. A process-based water balance model (Brook90) examines the influence of meteorological forcing on evapotranspiration (ET) rates in the valley. The model results suggest that cloud-free daylight conditions enhances ET during the wet season. ET was insignificant throughout the dry season. In addition, we report on the effects of elevation on ET.

  15. 7 CFR 58.923 - Filling containers.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filling containers. 58.923 Section 58.923 Agriculture... Procedures § 58.923 Filling containers. (a) The filling of small containers with product shall be done in a sanitary manner. The containers shall not contaminate or detract from the quality of the product in any way...

  16. Ice flow models and glacial erosion over multiple glacial–interglacial cycles

    OpenAIRE

    Headley, R. M.; Ehlers, T. A.

    2015-01-01

    Mountain topography is constructed through a variety of interacting processes. Over glaciological timescales, even simple representations of glacial-flow physics can reproduce many of the distinctive features formed through glacial erosion. However, detailed comparisons at orogen time and length scales hold potential for quantifying the influence of glacial physics in landscape evolution models. We present a comparison using two different numerical models for glacial flow ov...

  17. Long Valley Caldera Lake and reincision of Owens River Gorge

    Science.gov (United States)

    Hildreth, Wes; Fierstein, Judy

    2016-12-16

    Owens River Gorge, today rimmed exclusively in 767-ka Bishop Tuff, was first cut during the Neogene through a ridge of Triassic granodiorite to a depth as great as its present-day floor and was then filled to its rim by a small basaltic shield at 3.3 Ma. The gorge-filling basalt, 200 m thick, blocked a 5-km-long reach of the upper gorge, diverting the Owens River southward around the shield into Rock Creek where another 200-m-deep gorge was cut through the same basement ridge. Much later, during Marine Isotope Stage (MIS) 22 (~900–866 ka), a piedmont glacier buried the diversion and deposited a thick sheet of Sherwin Till atop the basalt on both sides of the original gorge, showing that the basalt-filled reach had not, by then, been reexcavated. At 767 ka, eruption of the Bishop Tuff blanketed the landscape with welded ignimbrite, deeply covering the till, basalt, and granodiorite and completely filling all additional reaches of both Rock Creek canyon and Owens River Gorge. The ignimbrite rests directly on the basalt and till along the walls of Owens Gorge, but nowhere was it inset against either, showing that the basalt-blocked reach had still not been reexcavated. Subsidence of Long Valley Caldera at 767 ka produced a steep-walled depression at least 700 m deeper than the precaldera floor of Owens Gorge, which was beheaded at the caldera’s southeast rim. Caldera collapse reoriented proximal drainages that had formerly joined east-flowing Owens River, abruptly reversing flow westward into the caldera. It took 600,000 years of sedimentation in the 26-km-long, usually shallow, caldera lake to fill the deep basin and raise lake level to its threshold for overflow. Not until then did reestablishment of Owens River Gorge begin, by incision of the gorge-filling ignimbrite.

  18. Timing of glacier advances and climate in the High Tatra Mountains (Western Carpathians) during the Last Glacial Maximum

    Science.gov (United States)

    Makos, Michał; Dzierżek, Jan; Nitychoruk, Jerzy; Zreda, Marek

    2014-07-01

    During the Last Glacial Maximum (LGM), long valley glaciers developed on the northern and southern sides of the High Tatra Mountains, Poland and Slovakia. Chlorine-36 exposure dating of moraine boulders suggests two major phases of moraine stabilization, at 26-21 ka (LGM I - maximum) and at 18 ka (LGM II). The dates suggest a significantly earlier maximum advance on the southern side of the range. Reconstructing the geometry of four glaciers in the Sucha Woda, Pańszczyca, Mlynicka and Velicka valleys allowed determining their equilibrium-line altitudes (ELAs) at 1460, 1460, 1650 and 1700 m asl, respectively. Based on a positive degree-day model, the mass balance and climatic parameter anomaly (temperature and precipitation) has been constrained for LGM I advance. Modeling results indicate slightly different conditions between northern and southern slopes. The N-S ELA gradient finds confirmation in slightly higher temperature (at least 1 °C) or lower precipitation (15%) on the south-facing glaciers during LGM I. The precipitation distribution over the High Tatra Mountains indicates potentially different LGM atmospheric circulation than at the present day, with reduced northwesterly inflow and increased southerly and westerly inflows of moist air masses.

  19. Glacial Influences on Solar Radiation in a Subarctic Sea.

    Science.gov (United States)

    Understanding macroscale processes controlling solar radia­tion in marine systems will be important in interpreting the potential effects of global change from increasing ultraviolet radiation (UV) and glacial retreat. This study provides the first quantitative assessment of UV i...

  20. Geometric dependency of Tibetan lakes on glacial runoff

    NARCIS (Netherlands)

    Phan Hien, V.; Lindenbergh, R.C.; Menenti, M.

    2013-01-01

    The Tibetan Plateau is an essential source of water for Southeast Asia. The runoff from its ~34 000 glaciers, which occupy an area of ~50 000 km2, feeds Tibetan lakes and major Asian rivers like the Indus and Brahmaputra. Reported glacial shrinkage likely has an impact on the runoff. Unfortunately,

  1. Inherent characteristics of sawtooth cycles can explain different glacial periodicities

    NARCIS (Netherlands)

    Omta, A.W.; Kooi, B.W.; van Voorn, G.A.K.; Rickaby, R.E.M; Follows, M.J.

    2016-01-01

    At the Mid-Pleistocene Transition about 1 Ma, the dominant periodicity of the glacial-interglacial cycles shifted from ~40 to ~100 kyr. Here, we use a previously developed mathematical model to investigate the possible dynamical origin of these different periodicities. The model has two variables,

  2. Inherent characteristics of sawtooth cycles can explain different glacial periodicities

    NARCIS (Netherlands)

    Omta, Anne Willem; Kooi, Bob W.; Voorn, van G.A.K.; Rickaby, Rosalind E.M.; Follows, Michael J.

    2016-01-01

    At the Mid-Pleistocene Transition about 1 Ma, the dominant periodicity of the glacial-interglacial cycles shifted from ~40 to ~100 kyr. Here, we use a previously developed mathematical model to investigate the possible dynamical origin of these different periodicities. The model has two

  3. Testing Hypotheses About Glacial Cycles Against the Observational Record

    DEFF Research Database (Denmark)

    Kaufmann, Robert; Juselius, Katarina

    2013-01-01

    We estimate an identified cointegrated vector autoregression (CVAR) model of the climate system to test hypotheses about the physical mechanisms that may drive glacial cycles during the late Pleistocene. Results indicate that a permanent doubling of CO2 generates a 11.1oC rise in Antarctic...

  4. Glacial isostatic stress shadowing by the Antarctic ice sheet

    Science.gov (United States)

    Ivins, E. R.; James, T. S.; Klemann, V.

    2005-01-01

    Numerous examples of fault slip that offset late Quaternary glacial deposits and bedrock polish support the idea that the glacial loading cycle causes earthquakes in the upper crust. A semianalytical scheme is presented for quantifying glacial and postglacial lithospheric fault reactivation using contemporary rock fracture prediction methods. It extends previous studies by considering differential Mogi-von Mises stresses, in addition to those resulting from a Coulomb analysis. The approach utilizes gravitational viscoelastodynamic theory and explores the relationships between ice mass history and regional seismicity and faulting in a segment of East Antarctica containing the great Antarctic Plate (Balleny Island) earthquake of 25 March 1998 (Mw 8.1). Predictions of the failure stress fields within the seismogenic crust are generated for differing assumptions about background stress orientation, mantle viscosity, lithospheric thickness, and possible late Holocene deglaciation for the D91 Antarctic ice sheet history. Similar stress fracture fields are predicted by Mogi-von Mises and Coulomb theory, thus validating previous rebound Coulomb analysis. A thick lithosphere, of the order of 150-240 km, augments stress shadowing by a late melting (middle-late Holocene) coastal East Antarctic ice complex and could cause present-day earthquakes many hundreds of kilometers seaward of the former Last Glacial Maximum grounding line.

  5. Atlantic Meridional Overturning Circulation During the Last Glacial Maximum.

    NARCIS (Netherlands)

    Lynch-Stieglitz, J.; Adkins, J.F.; Curry, W.B.; Dokken, T.; Hall, I.R.; Herguera, J.C.; Hirschi, J.J.-M.; Ivanova, E.V.; Kissel, C.; Marchal, O.; Marchitto, T.M.; McCave, I.N.; McManus, J.F.; Mulitza, S.; Ninnemann, U.; Peeters, F.J.C.; Yu, E.-F.; Zahn, R.

    2007-01-01

    The circulation of the deep Atlantic Ocean during the height of the last ice age appears to have been quite different from today. We review observations implying that Atlantic meridional overturning circulation during the Last Glacial Maximum was neither extremely sluggish nor an enhanced version of

  6. 76 FR 50476 - Application To Export Electric Energy; Glacial Energy of Texas, Inc.

    Science.gov (United States)

    2011-08-15

    ... DEPARTMENT OF ENERGY [OE Docket No. EA-382] Application To Export Electric Energy; Glacial Energy... Application. SUMMARY: Glacial Energy of Texas, Inc. (Glacial) has applied for authority to transmit electric... for authority to transmit electric energy from the United States to Mexico for five years as a power...

  7. Cosmogenic 10Be ages from the Meirs and Garwood Valleys, Denton Hills, West Antarctica, suggest an absence in LGM Ice Sheet expansion.

    Science.gov (United States)

    Fink, David; Joy, Kurt; Storey, Bryan

    2014-05-01

    It has been hypothesised that during interglacials, thinning of the Ross Ice Shelf allowed a more open water environment with increased local precipitation. This resulted in outlet glaciers, which drain the Transantarctic Mountains and fed by the East Antarctic Ice Sheet, advancing during moist warmer periods, apparently out of phase with colder arid dry periods. Significantly the ice core record during these warm periods also shows increased accumulation continent wide The geomorphology of the Denton Hills in the Royal Society Range, West Antarctica, is a result of Miocene fluvial incision reworked by subsequent glacial advances throughout the Quaternary. The Garwood and Miers glacial valleys drain ice across the Denton Hills into the Shelf, and should thus show maximum extent during interstadials. To understand the chronology of late Quaternary glaciations, 15 granitic boulders from terminal moraines were sampled for 10Be and 26Al cosmogenic dating. Obtaining reliable exposure ages of erratics within moraines that represent timing of deposition (i.e. glacial advances) is problematic in polar regions, where glacial activity is principally controlled by ice sheet dynamics. Recycling of previously exposed debris, uncertainty in provenance of glacially transported boulders and a lack of a post-depositional hydrologic process to remove previously exposed material from a valley system, leads to ambiguities in multiple exposure ages from a single coeval glacial landform. More importantly, cold-based ice advance can leave a landform unmodified resulting in young erratics deposited on bedrock that shows weathering and/or inconsistent age-altitude relationships. Primarily, inheritance becomes a difficulty in qualifying exposure ages from polar regions. Preliminary results from the Garwood and Miers Valleys indicate that glaciers in the Denton Hills had begun to retreat from their last maximum positions no later than 23-37 ka, and thus the local last glacial maximum

  8. Microhardness of bulk-fill composite materials

    OpenAIRE

    Kelić, Katarina; Matić, Sanja; Marović, Danijela; Klarić, Eva; Tarle, Zrinka

    2016-01-01

    The aim of the study was to determine microhardness of high- and low-viscosity bulk-fill composite resins and compare it with conventional composite materials. Four materials of high-viscosity were tested, including three bulk-fills: QuiXfi l (QF), x-tra fil (XTF) and Tetric EvoCeram Bulk Fill (TEBCF), while nanohybrid composite GrandioSO (GSO) served as control. The other four were low-viscosity composites, three bulk-fill materials: Smart Dentin Replacement (SDR), Venus Bulk Fill (VBF) and ...

  9. The use of multibeam backscatter intensity data as a tool for mapping glacial deposits in the Central North Sea, UK

    Science.gov (United States)

    Stewart, Heather; Bradwell, Tom

    2014-05-01

    gravelly sands and sandy gravels compared to the surrounding sandy and muddy sediments. Moraines are indicated as areas of high backscatter intensity and comprise coarse grained sediments. A range of moraine sizes have been identified from large scale moraines reflecting both frontal still stands or re-advances of the ice-sheet margin, de geer moraines and smaller moraines that may represent annual variations. Meltwater channels and tunnel valleys are revealed as areas of low backscatter intensity reflecting post-glacial soft sediment infill of the depressions incised into coarser grained and higher strength glacial deposits by these features.

  10. Shifting sources and transport paths for the late Quaternary Escanaba Trough sediment fill (northeast Pacific)

    Science.gov (United States)

    Zuffa, G.G.; De Rosa, R.; Normark, W.R.

    1997-01-01

    Escanaba Trough, which forms the southernmost part of the axial valley of the actively spreading Gorda Ridge, is filled with several hundred meters of sediment of presumed late Quaternary age. Surficial sediment samples from gravity cores, deeper samples (as much as 390 m) from Site 35 of the Deep Sea Drilling Program (Leg 5), and the acoustic character of the sediment fill observed on seismic-reflection profiles indicate that much of the sediment fill is of turbidite origin. Gross composition and heavy- mineral analyses of sand samples show that two distinct petrofacies comprise the sediment fill. The lower part of the fill was derived primarily from the Klamath River source of northern California while the younger fill, including the surficial sand beds, are from the Columbia River drainage much farther north. The Escanaba Trough sediment provides an opportunity to evaluate concepts for paleogeographic and paleotectonic reconstructions that are based on facies analysis and compositional and textural data for the volcanic components because both intrabasinal and extrabasinal sources are present as well as coeval (neovolcanic) and non coeval (paleovolcanic) sourcre This study of a modern basin shows, that although the sediment sources could be identified, it was useful to have some knowledge of the sediment pathway(s), the effects of diagenesis, and the possible effects of sediment sorting as a result of long transport distances from the source area for some components. Application of these same techniques to ancient deposits without benefit of the additional parameters will face limitations.

  11. Influence of glacial meltwater on global seawater δ234U

    Science.gov (United States)

    Arendt, Carli A.; Aciego, Sarah M.; Sims, Kenneth W. W.; Das, Sarah B.; Sheik, Cody; Stevenson, Emily I.

    2018-03-01

    We present the first published uranium-series measurements from modern Greenland Ice Sheet (GrIS) runoff and proximal seawater, and investigate the influence of glacial melt on global seawater δ234U over glacial-interglacial (g-ig) timescales. Climate reconstructions based on closed-system uranium-thorium (U/Th) dating of fossil corals assume U chemistry of seawater has remained stable over time despite notable fluctuations in major elemental compositions, concentrations, and isotopic compositions of global seawater on g-ig timescales. Deglacial processes increase weathering, significantly increasing U-series concentrations and changing the δ234U of glacial meltwater. Analyses of glacial discharge from GrIS outlet glaciers indicate that meltwater runoff has elevated U concentrations and differing 222Rn concentrations and δ234U compositions, likely due to variations in subglacial residence time. Locations with high δ234U have the potential to increase proximal seawater δ234U. To better understand the impact of bulk glacial melt on global seawater δ234U over time, we use a simple box model to scale these processes to periods of extreme deglaciation. We account for U fluxes from the GrIS, Antarctica, and large Northern Hemisphere Continental Ice Sheets, and assess sensitivity by varying melt volumes, duration and U flux input rates based on modern subglacial water U concentrations and compositions. All scenarios support the hypothesis that global seawater δ234U has varied by more than 1‰ through time as a function of predictable perturbations in continental U fluxes during g-ig periods.

  12. Review of fill mining technology in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K. H.; Hedley, D. G.F.

    1980-05-15

    The Canadian mining industry has a long history of being in the fore-front in developing new technology in underground hardrock mines. Examples include the development of hydraulic and cemented fills, undercut-and-fill, mechanized cut-and-fill, post pillar, vertical retreat and blasthole mining methods. The evolution of this technology is briefly described in an historical review. Backfill serves many functions, although it is generally considered in terms of its support capabilities. These functions, mainly related to the mining method used, are evaluated in regard to regional support, pillar support, fill roof, working floor, dilution control and waste disposal. With the advent of blasthole and vertical retreat methods for pillar recovery operations, the freestanding height of backfill walls has assumed greater importance. Consequently, more attention is being given to what fill properties are required to achieve fill wall exposures up to 25 m wide by 90 m high. With the large increases in energy costs, alternatives to partially replace Portland cement in fill are being examined. The validation of mining concepts and the interaction of backfill is perhaps best evaluated by in-situ measurements. Examples are given of stress, deformation and fill pressure measurements in longitudinal cut-and-fill, post pillar mining and blasthole stoping with delayed fill which were taken in several mines in Canada. Finally, the overall design procedure used in deciding mining method, stope and pillar dimensions, sequence of extraction, fill properties and support systems at a new mine is described.

  13. Last Glacial Maximum and Lateglacial in the Polish High Tatra Mountains - Revised deglaciation chronology based on the 10Be exposure age dating

    Science.gov (United States)

    Makos, Michał; Rinterknecht, Vincent; Braucher, Régis; Tołoczko-Pasek, Anna; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim; Aster Team

    2018-05-01

    Deglaciation chronology of the Polish High Tatra Mountains has been reconstructed based on 10Be exposure age dating. Fifty-seven rock samples were collected from boulders located on the terminal and lateral moraines that limit the horizontal extent of the LGM and the Lateglacial glaciers in the Biała Woda and Sucha Woda catchments. The uncertainty-weighted mean age of 21.5 ± 2.5 ka obtained for the maximum terminal moraine in the Sucha Woda Valley indicates that the oldest preserved moraines were formed during the global LGM. The age population ranges between 15.1 ± 1.0 and 28.3 ± 2.0 ka, and suggests that glaciers reached their maximum position (LGM I) as early as 28-25 ka and the final stabilization of the form occurred much later possibly after melting of buried dead ice. The younger glacial oscillation (LGM II) occurred no later than 20.5 ka and is represented by well-preserved termino-lateral moraine systems in the Pańszczyca Valley. The first Lateglacial stage (LG1) in the study area is documented in the Rybi Potok Valley at the RP1 moraine (1300 m a.s.l.), which was stable at around 16.6 ± 0.3 ka. The younger LG2 stage has no defined absolute age, however, it is constrained between 16.5 and 15.5 ka by the timing of the LG3 stage. This cold event is represented by well-formed moraines in the Roztoka/Pięć Stawów Polskich, Rybi Potok and Pańszczyca valleys of which exposure age indicates their deposition between 15.0 ± 0.5 and 15.6 ± 0.1 ka. The LG1, LG2 and LG3 stages likely occurred during the Oldest Dryas cold stage (Greenland Stadial 2.1a) related to the North Atlantic cooling Heinrich Event 1. The youngest glacial oscillation is evidenced by moraines in the Pusta and Pańszczyca valleys. These moraines are composed of very large granitic blocks of which exposure ages often exhibit isotope inheritance. This is reflected by the youngest P3 moraine in the Pańszczyca Valley with a mean age of deposition close to the LGM. The R4 moraine system in

  14. Operation feedback of hydrogen filling station

    International Nuclear Information System (INIS)

    Pregassame, S.; Barral, K.; Allidieres, L.; Charbonneau, T.; Lacombe, Y.

    2004-01-01

    One of the technical challenges of hydrogen technology is the development of hydrogen infrastructures which satisfy either safety requirements and reliability of filling processes. AIR LIQUIDE realized an hydrogen filling station in Sassenage (France) operational since September 2003. This station is able to fill 3 buses a day up to 350bar by equilibrium with high pressure buffers. In parallel with commercial stations, the group wanted to create a testing ground in real conditions running with several objectives: validate on a full scale bench a simulation tool able to predict the temperature of both gas and cylinder's materials during filling processes; define the best filling procedures in order to reach mass, temperature and filling time targets; analyse the temperature distribution and evolution inside the cylinder; get a general knowledge about hydrogen stations from safety and reliability point of view; operate the first full scale refuelling station in France. The station is also up-graded for 700bar filling from either a liquid hydrogen source or a gas booster, with cold filling possibility. This paper presents the results concerning 350bar filling : thermal effects, optimal filling procedures and influence of parameters such as climatic conditions are discussed. (author)

  15. Dielectric-filled radiofrequency linacs

    Energy Technology Data Exchange (ETDEWEB)

    Faehl, R J; Keinigs, R K; Pogue, E W [Los Alamos National Lab., NM (United States)

    1997-12-31

    High current, high brightness electron beam accelerators promise to open up dramatic new applications. Linear induction accelerators are currently viewed as the appropriate technology for these applications. A concept by Humphries and Hwang may permit radiofrequency accelerators to fulfill the same functions with greater simplicity and enhanced flexibility. This concept involves the replacement of vacuum rf cavities with dielectric filled ones. Simple analysis indicates that the resonant frequencies are reduced by a factor of ({epsilon}{sub 0}/{epsilon}){sup 1/2} while the stored energy is increased by {epsilon}/{epsilon}{sub 0}. For a high dielectric constant like water, this factor can approach 80. A series of numerical calculations of simple pill-box cavities was performed. Eigenfunctions and resonant frequencies for a full system configuration, including dielectric material, vacuum beamline, and a ceramic window separating the two have been computed. These calculations are compared with the results of a small experimental cavity which have been constructed and operated. Low power tests show excellent agreement. (author). 4 figs., 8 refs.

  16. Sediment core and glacial environment reconstruction - a method review

    Science.gov (United States)

    Bakke, Jostein; Paasche, Øyvind

    2010-05-01

    Alpine glaciers are often located in remote and high-altitude regions of the world, areas that only rarely are covered by instrumental records. Reconstructions of glaciers has therefore proven useful for understanding past climate dynamics on both shorter and longer time-scales. One major drawback with glacier reconstructions based solely on moraine chronologies - by far the most common -, is that due to selective preservation of moraine ridges such records do not exclude the possibility of multiple Holocene glacier advances. This problem is true regardless whether cosmogenic isotopes or lichenometry have been used to date the moraines, or also radiocarbon dating of mega-fossils buried in till or underneath the moraines themselves. To overcome this problem Karlén (1976) initially suggested that glacial erosion and the associated production of rock-flour deposited in downstream lakes could provide a continuous record of glacial fluctuations, hence overcoming the problem of incomplete reconstructions. We want to discuss the methods used to reconstruct past glacier activity based on sediments deposited in distal glacier-fed lakes. By quantifying physical properties of glacial and extra-glacial sediments deposited in catchments, and in downstream lakes and fjords, it is possible to isolate and identify past glacier activity - size and production rate - that subsequently can be used to reconstruct changing environmental shifts and trends. Changes in average sediment evacuation from alpine glaciers are mainly governed by glacier size and the mass turnover gradient, determining the deformation rate at any given time. The amount of solid precipitation (mainly winter accumulation) versus loss due to melting during the ablation-season (mainly summer temperature) determines the mass turnover gradient in either positive or negative direction. A prevailing positive net balance will lead to higher sedimentation rates and vice versa, which in turn can be recorded in downstream

  17. The Glacial BuzzSaw, Isostasy, and Global Crustal Models

    Science.gov (United States)

    Levander, A.; Oncken, O.; Niu, F.

    2015-12-01

    The glacial buzzsaw hypothesis predicts that maximum elevations in orogens at high latitudes are depressed relative to temperate latitudes, as maximum elevation and hypsography of glaciated orogens are functions of the glacial equilibrium line altitude (ELA) and the modern and last glacial maximum (LGM) snowlines. As a consequence crustal thickness, density, or both must change with increasing latitude to maintain isostatic balance. For Airy compensation crustal thickness should decrease toward polar latitudes, whereas for Pratt compensation crustal densities should increase. For similar convergence rates, higher latitude orogens should have higher grade, and presumably higher density rocks in the crustal column due to more efficient glacial erosion. We have examined a number of global and regional crustal models to see if these predictions appear in the models. Crustal thickness is straightforward to examine, crustal density less so. The different crustal models generally agree with one another, but do show some major differences. We used a standard tectonic classification scheme of the crust for data selection. The globally averaged orogens show crustal thicknesses that decrease toward high latitudes, almost reflecting topography, in both the individual crustal models and the models averaged together. The most convincing is the western hemisphere cordillera, where elevations and crustal thicknesses decrease toward the poles, and also toward lower latitudes (the equatorial minimum is at ~12oN). The elevation differences and Airy prediction of crustal thickness changes are in reasonable agreement in the North American Cordillera, but in South America the observed crustal thickness change is larger than the Airy prediction. The Alpine-Himalayan chain shows similar trends, however the strike of the chain makes interpretation ambiguous. We also examined cratons with ice sheets during the last glacial period to see if continental glaciation also thins the crust toward

  18. Sediment Thickness and a WEST-EAST Geologic Cross Section in the Caracas Valley

    OpenAIRE

    KANTAK, PETER; SCHMITZ, MICHAEL; AUDEMARD, FRANCK

    2005-01-01

    Caracas is located at the Caribbean - South America plate boundary zone, with an associated strike slip fault system, which accommodates the relative movement of both plates and is responsible for the seismic hazard in the region. The damage pattern of the 1967 Caracas earthquake emphasized the existence of important site effects due to the sedimentary basin fill of the Caracas valley. A revised map of the sedimentary thickness was developed during this study, based on drill holes (mostly fro...

  19. Preliminary appraisal of ground water in and near the ancestral Missouri River Valley, northeastern Montana

    Science.gov (United States)

    Levings, G.W.

    1986-01-01

    A preliminary appraisal was conducted in and near the ancestral Missouri River valley in northeastern Montana to describe the groundwater resources and to establish a data base for the area. The data base then could be used for future evaluation of possible changes in water levels or water quality. In this area, consolidated aquifers are the Upper Cretaceous Fox Hills-lower Hell Creek aquifer and the overlying Paleocene Fort Union Formation. Unconsolidated aquifers are Pleistocene terrace gravel and glacial deposits and Holocene alluvial deposits. Aquifers are recharged by precipitation, infiltration of streamflow, and possibly leakage from lakes and potholes. Groundwater moves from topographically higher areas to the ancestral valley, then along the ancestral valley to the southwest. Water is discharged from aquifers by evapotranspiration, springs and seeps, movement directly into streams and lakes, and from pumping wells. Average well yields are greatest for irrigation wells completed in outwash gravel (886 gallons/min). Eighteen wells were completed in various aquifers to monitor potential long-term changes in water levels and water quality. Measured water levels declined about 2 ft. or less during the study (1982-85). Chemical analysis of groundwater samples indicated that concentrations of some dissolved constituents exceeded U.S. Environmental Protection Agency standards for drinking water. (USGS)

  20. Periodic isolation of the southern coastal plain of South Africa and the evolution of modern humans over late Quaternary glacial to interglacial cycles

    Science.gov (United States)

    Compton, J. S.

    2012-04-01

    select for humans who expanded their diet to include marine resources or hunted large animals. Modest expansion of the coastal plain off Morocco and more extensive expansion off Tunisia would have similarly provided potential refugia for human groups during glacial periods. Other refugia in the African interior included the Ethiopian Highlands and the East African lakes; however, most of these regions probably had more diffuse barriers connected by river valley corridors. The earliest yet reported occurrence of symbolic artifacts from both North Africa and the SCP coastal caves of South Africa suggest that human populations in these areas were under shared selection pressures to adapt to increasing population densities associated with the transition from Marine Isotope Stage (MIS) 6 to 5, 135 to 130 thousand years ago. The hypothesis that periodic expansion and contraction of the coastal plains of South Africa and North Africa contributed to the stepwise origin of our species over the last 800 thousand years is evaluated by comparing the archeological, DNA and sea-level records.

  1. The timing and cause of glacial activity during the last glacial in central Tibet based on 10Be surface exposure dating east of Mount Jaggang, the Xainza range

    Science.gov (United States)

    Dong, Guocheng; Zhou, Weijian; Yi, Chaolu; Fu, Yunchong; Zhang, Li; Li, Ming

    2018-04-01

    Mountain glaciers are sensitive to climate change, and can provide valuable information for inferring former climates on the Tibetan Plateau (TP). The increasing glacial chronologies indicate that the timing of the local Last Glacial Maximum (LGM) recorded across the TP is asynchronous, implying different local influences of the mid-latitude westerlies and Asian Summer Monsoon in triggering glacier advances. However, the well-dated sites are still too few, especially in the transition zone between regions controlled by the two climate systems. Here we present detailed last glacial chronologies for the Mount Jaggang area, in the Xainza range, central Tibet, with forty-three apparent 10Be exposure-ages ranging from 12.4 ± 0.8 ka to 61.9 ± 3.8 ka. These exposure-ages indicate that at least seven glacial episodes occurred during the last glacial cycle east of Mount Jaggang. These include: a local LGM that occurred at ∼61.9 ± 3.8 ka, possibly corresponding to Marine Isotope Stage 4 (MIS 4); subsequent glacial advances at ∼43.2 ± 2.6 ka and ∼35.1 ± 2.1 ka during MIS 3; one glacial re-advance/standstill at MIS3/2 transition (∼29.8 ± 1.8 ka); and three glacial re-advances/standstills that occurred following MIS 3 at ∼27.9 ± 1.7 ka, ∼21.8 ± 1.3 ka, and ∼15.1 ± 0.9 ka. The timing of these glacial activities is roughly in agreement with North Atlantic millennial-scale climate oscillations (Heinrich events), suggesting the potential correlations between these abrupt climate changes and glacial fluctuations in the Mount Jaggang area. The successively reduced glacial extent might have resulted from an overall decrease in Asian Summer Monsoon intensity over this timeframe.

  2. Iron filled carbon nanostructures from different precursors

    International Nuclear Information System (INIS)

    Costa, S.; Borowiak-Palen, E.; Bachmatiuk, A.; Ruemmeli, M.H.; Gemming, T.; Kalenczuk, R.J.

    2008-01-01

    Here, we present a study on the synthesis of different nanostructures with one single-step in situ filling (encapsulation) via carbon vapor deposition (CVD). Ferrocene, acetylferrocene and iron (II) nitrate as iron precursors were explored. The application of each of these compounds resulted in different carbon nanomaterials such as: iron filled multiwalled carbon nanotubes with a low filling ratio (Fe-MWCNT), iron filled nanocapsules and unfilled MWCNT. The as-produced samples were purified by high temperature annealing and acid treatment. The purified materials were characterised using transmission electron microscopy (TEM) and Raman spectroscopy

  3. Characterization of Low Density Glass Filled Epoxies

    National Research Council Canada - National Science Library

    Quesenberry, Matthew

    2003-01-01

    This report discusses the experimental determination and modeling of several thermophysical and mechanical properties of glass filled epoxy composite systems for potential use as electronic potting compounds...

  4. The distribution of glacial erratics in the Northeast Atlantic

    International Nuclear Information System (INIS)

    Huggett, Q.

    1985-01-01

    A detailed study of all the available information on glacial erratics has been carried out. This has included an examination of 288 dredge hauls, 1164 sediment cores and 176 camera runs. Sufficient data have now been collected to provide an estimate of the impact risk of a point projectile with a glacial erratic, down to oxygen isotope stage 5 (127,000 years) in three areas of the North East Atlantic. 1. Porcupine seabight (50 deg N, 14 deg W) 0.460%; 2. King's Trough Flank (42 deg N, 24 deg W) 0.502%; 3. Great Meteor East (31 deg N, 25 deg W) 0.015%. These estimates are for all erratics larger than 1.5 cm diameter and apply only down to oxygen isotope stage 5. If estimates are required at greater depths than this, it is proposed that a detailed study of a long core should be undertaken. (author)

  5. Environmental conditions of interstadial (MIS 3 and features of the last glacial maximum on the King George island (West Antarctica

    Directory of Open Access Journals (Sweden)

    S. R. Verkulich

    2013-01-01

    Full Text Available The interstadial marine deposits stratum was described in the Fildes Peninsula (King George Island due to field and laboratory investigations during 2008–2011. The stratum fragments occur in the west and north-west parts of peninsula in following forms: sections of soft sediments, containing fossil shells, marine algae, bones of marine animals and rich marine diatom complexes in situ (11 sites; fragments of shells and bones on the surface (25 sites. According to the results of radiocarbon dating, these deposits were accumulated within the period 19–50 ky BP. Geographical and altitude settings of the sites, age characteristics, taxonomy of fossil flora and fauna, and good safety of the soft deposits stratum allow to make following conclusions: during interstadial, sea water covered significant part of King George Island up to the present altitude of 40 m a.s.l., and the King George Island glaciation had smaller size then; environmental conditions for the interstadial deposit stratum accumulation were at least not colder than today; probably, the King George island territory was covered entirely by ice masses of Last glacial maximum not earlier than 19 ky BP; during Last glacial maximum, King George Island was covered by thin, «cold», not mobile glaciers, which contribute to conservation of the soft marine interstadial deposits filled with fossil flora and fauna.

  6. Distribution of anthropogenic fill material within the Y-12 plant area, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Sutton, G.E. Jr.; Field, S.M.

    1995-10-01

    Widespread groundwater contamination in the vicinity of the Oak Ridge Y-12 Plant has been documented through a variety of monitoring efforts since the late 1970s. Various contaminants, most notably volatile organic compounds (VOCs), have migrated through the subsurface and formed extensive contaminant plumes within the Knox Aquifer/Maynardville Limestone, the primary exit pathway for groundwater transport within the Bear Creek Valley. In 1991, an integrated, comprehensive effort (Upper East Fork Poplar Creek [UEFPC] Phase I monitoring network) was initiated in order to (1) identify contaminant source areas within the industrialized portions of the plant and (2) define contamination migration pathways existing between the source areas and the Knox Aquifer/Maynardville Limestone. Data obtained during previous studies have indicated that extensive zones of fill and buried utility trenches may serve as preferred migration pathways. In addition, portions of UEFPC were rerouted, with several of its tributaries being filled during the initial construction of the plant. These filled surface drainage features are also believed to serve as preferred migration pathways. The identification of preferred contaminant migration pathways within the Y-12 Plant area is essential and required to refine the current Bear Creek Valley groundwater conceptual model and to assist in the selection of technically feasible and cost effective remedial strategies. This report presents the results of an initial investigation of the occurrence of manmade (anthropogenic) fill and its effect upon groundwater movement within the plant area. These interpretations are subject to revision and improvement as further investigation of the effects of the fill upon contaminant migration progresses

  7. Impacts on the Yukon and the Mackenzie Valley

    International Nuclear Information System (INIS)

    Parker, N.; Cowan, C.

    1993-01-01

    Climate models predicting the effects of global warming due to the greenhouse effect give rough estimates of the sign and size of expected changes in temperature and precipitation. However, these models do not show what to expect from a warmer regional climate. One approach to resolve this issue is to use climate information from past years and find a year whose climate is close to what the models say will exist in the future. This approach is used to gain some understanding into what climatic warming may mean to the Yukon and Mackenzie Valley areas of Arctic Canada. The summer of 1989, one of the warmest summers on record, is studied to examine the effects of climate warming on agriculture, stream flow, glacial melting, permafrost degradation, and forest fires. Under a climate scenario in which the 1989 summer became the average, agricultural land classification would increase although moisture and soil suitability would still limit many crops. Lower-level glaciers would likely continue their rapid melt while some higher-level glaciers and snowfields might expand due to increased moisture, especially during winter. 10 refs., 5 figs., 4 tabs

  8. Discovery of a landscape-wide drape of late-glacial aeolian silt in the western Northern Calcareous Alps (Austria): First results and implications

    Science.gov (United States)

    Gild, Charlotte; Geitner, Clemens; Sanders, Diethard

    2018-01-01

    Aeolian deposits record palaeoenvironmental conditions and may coin soil properties. Whereas periglacial loess is extensively investigated for 200 years, the study of the intramontane wind-blown deposits of the Alps has just stuttered along. Herein, we describe a drape of polymictic siliciclastic silt interpreted as an aeolian deposit that veneers extensive areas in the western Northern Calcareous Alps (NCA), from kames terraces near valley floors up to last-glacial nunataks. The NCA - part of the Eastern Alps mountain range - consist mainly of Triassic carbonate rocks; these are overlain by deposits of the Last Glacial Maximum (LGM) and its deglacial-paraglacial aftermath (e.g., glacial tills, fluvio-lacustrine successions, alluvial fans, scree slopes) - and a regional drape of polymictic silt newly described herein. The drape is typically a few decimeters in thickness and slightly modified by soil formation; it consists mainly of well-sorted silt of quartz, feldspars, phyllosilicates (muscovite, chlorite, biotite), amphiboles and, rarely, calcite or dolomite. The drape is unrelated to the substrate: it overlies carbonate bedrock and - in lateral continuity - abandoned deposystems such as colluvial slopes of redeposited till, kames, alluvial fans, scree slopes, and rock avalanche deposits. The drape was spotted from near the present valley floors up to LGM nunataks, over a vertical range of some 2000 m; it is also present in catchments of the NCA that were not overridden by far-travelled ice streams and that lack metamorphic rock fragments. Two OSL quartz ages of the drape from two distinct locations (18.77 ± 1.55 ka; 17.81 ± 1.68 ka) fall into the early Alpine late-glacial interval shortly after the collapse of pleniglacial ice streams; this fits with geological and geomorphological evidence, respectively, that the drape should be of early late-glacial age, and that it accumulated during a specific interval of time. In the NCA, localized minor deposition of

  9. Glacial cycles:exogenous orbital changes vs. endogenous climate dynamics

    OpenAIRE

    Kaufmann, R. K.; Juselius, Katarina

    2010-01-01

    We use a statistical model, the cointegrated vector autoregressive model, to assess the degree to which variations in Earth's orbit and endogenous climate dynamics can be used to simulate glacial cycles during the late Quaternary (390 kyr-present). To do so, we estimate models of varying complexity and compare the accuracy of their in-sample simulations. Results indicate that strong statistical associations between endogenous climate variables are not enough for statistical models to reproduc...

  10. Uncovering the glacial history of the Irish continental shelf (Invited)

    Science.gov (United States)

    Dunlop, P.; Benetti, S.; OCofaigh, C.

    2013-12-01

    In 1999 the Irish Government initiated a €32 million survey of its territorial waters known as the Irish National Seabed Survey (INSS). The INSS is amongst the largest marine mapping programmes ever undertaken anywhere in the world and provides high-resolution multibeam, backscatter and seismic data of the seabed around Ireland. These data have been used to provide the first clear evidence for extensive glaciation of the continental shelf west and northwest of Ireland. Streamlined drumlins on the mid to outer shelf record former offshore-directed ice flow towards the shelf edge and show that the ice sheet was grounded in a zone of confluence where ice flowing onto the shelf from northwest Ireland merged with ice flowing across the Malin Shelf from southwest Scotland. The major glacial features on the shelf are well developed nested arcuate moraine systems that mark the position of the ice sheet margin and confirm that the former British Irish Ice Sheet was grounded as far as the shelf edge around 100 km offshore of west Donegal at the last glacial maximum. Distal to the moraines, on the outermost shelf, prominent zones of iceberg plough marks give way to the Barra/Donegal fan and a well developed system of gullies and canyons which incise the continental slope. Since 2008 several scientific cruises have retrieved cores from the shelf and slope to help build a more detailed understanding of glacial events in this region. This presentation will provide an overview of the glacial history of the Irish shelf and will discuss ongoing research programmes that are building on the initial research findings to produce a better understanding of the nature and timing of ice sheet events in this region.

  11. The INTIMATE event stratigraphy of the last glacial period

    Science.gov (United States)

    Olander Rasmussen, Sune; Svensson, Anders

    2015-04-01

    The North Atlantic INTIMATE (INtegration of Ice-core, MArine and TErrestrial records) group has previously recommended an Event Stratigraphy approach for the synchronisation of records of the Last Termination using the Greenland ice core records as the regional stratotypes. A key element of these protocols has been the formal definition of numbered Greenland Stadials (GS) and Greenland Interstadials (GI) within the past glacial period as the Greenland expressions of the characteristic Dansgaard-Oeschger events that represent cold and warm phases of the North Atlantic region, respectively. Using a recent synchronization of the NGRIP, GRIP, and GISP2 ice cores that allows the parallel analysis of all three records on a common time scale, we here present an extension of the GS/GI stratigraphic template to the entire glacial period. In addition to the well-known sequence of Dansgaard-Oeschger events that were first defined and numbered in the ice core records more than two decades ago, a number of short-lived climatic oscillations have been identified in the three synchronized records. Some of these events have been observed in other studies, but we here propose a consistent scheme for discriminating and naming all the significant climatic events of the last glacial period that are represented in the Greenland ice cores. In addition to presenting the updated event stratigraphy, we make a series of recommendations on how to refer to these periods in a way that promotes unambiguous comparison and correlation between different proxy records, providing a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations. The work presented is a part of a newly published paper in an INTIMATE special issue of Quaternary Science Reviews: Rasmussen et al., 'A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event

  12. Deformed glacial deposits of Passamaquoddy Bay area, New Brunswick

    International Nuclear Information System (INIS)

    Kumarapeli, S.

    1990-03-01

    The New Brunswick-Maine border area, centred around Passamaquoddy Bay, is characterized by a distinctly higher level of seismic activity compared with the very low level background activity of the region. In this same general area, post-glacial deformation including faulting, has been observed in glaciofluvial and ice contact deposits and the possibility that these structures may in some way related to neotectonic movements in the area has been suggested. A study was undertaken to document these structures and to investigate their origin. The studies show that structures related to collapse of sediments due to melting of buried ice masses are the most prominent post-depositional structures in the glacial sediments. A second group of structures includes failure phenomena such as slumping. These require the action of a mechanism leading to reduction of sediment strength which could be achieved by seismic shaking. However, such failure phenomena could also be brought about by non-seismic processes, thus a unique interpretation of the origin of these structures is difficult, if not impossible. Since seismic shaking is the most effective, regionally extensive trigger of a broad group of failure phenomena in soft sediments, the related structures are usually spread over a large area, but are restricted to a very short time gap. Although the establishment of such space and time relationships may be feasible, for example in extensive lake deposits, it is difficult to do so in patchy laterally variable deposits such as the glacial deposits in Passamaquoddy Bay area

  13. Glacially-megalineated limestone terrain of Anticosti Island, Gulf of St. Lawrence, Canada; onset zone of the Laurentian Channel Ice Stream

    Science.gov (United States)

    Eyles, Nick; Putkinen, Niko

    2014-03-01

    Anticosti is a large elongate island (240 km long, 60 km wide) in eastern Canada within the northern part of a deep water trough (Gulf of St. Lawrence) that terminates at the Atlantic continental shelf edge. The island's Pleistocene glaciological significance is that its long axis lay transverse to ice from the Quebec and Labrador sectors of the Laurentide Ice Sheet moving south from the relatively high-standing Canadian Shield. Recent glaciological reconstructions place a fast-flowing ice stream along the axis of the Gulf of St. Lawrence but supporting geologic evidence in terms of recognizing its hard-bedded onset zone and downstream streamlined soft bed is limited. Anticosti Island consists of gently southward-dipping limestone plains composed of Ordovician and Silurian limestones (Vaureal, Becscie and Jupiter formations) with north-facing escarpments transverse to regional ice flow. Glacial deposits are largely absent and limestone plains in the higher central plateau of the island retain a relict apparently ‘preglacial’ drainage system consisting of deeply-incised dendritic bedrock valleys. In contrast, the bedrock geomorphology of the lower lying western and eastern limestone plains of the island is strikingly different having been extensively modified by glacial erosion. Escarpments are glacially megalineated with a distinct ‘zig-zag’ planform reflecting northward-projecting bullet-shaped ‘noses’ (identified as rock drumlins) up to 2 km wide at their base and 4 km in length with rare megagrooved upper surfaces. Drumlins are separated by southward-closing, funnel-shaped ‘through valleys’ where former dendritic valleys have been extensively altered by the streaming of basal ice through gaps in the escarpments. Glacially-megalineated bedrock terrain such as on the western and eastern flanks of Anticosti Island is elsewhere associated with the hard-bedded onset zones of fast flowing ice streams and provides important ground truth for the

  14. AIR POLLUTION FEATURES OF THE VALLEY-BASED TOWNS IN HUNGARY

    Directory of Open Access Journals (Sweden)

    Z. UTASI

    2016-03-01

    Full Text Available There are 30 valley-based towns with >10,000 inhabitants in Hungary, filled by 1.023 million people i.e. 10 % of the population. Two criteria are used to define the valley-based town. They are: (i Vertical difference between the lowest point in the town and the highest one around it should be >100 m. At the same time, (ii the same difference on the opposite side should be >50 m. Air pollution data by the National Air Pollution Observation Network are used. Five contaminants were selected and analysed for 2007, 2010 and 2013. Due to a sharp reduction in the network, we could find data for a small part of the valley-based towns. Control towns with equal air-quality observations and similar cumulative number of inhabitants were also selected. The contaminants and the number of the settlements are: NO2 manual (14 valley-based vs. 2x14 control, NO2 automatic (8 vs. 8, SO2 automatic (7 vs. 2x6, PM10 automatic (8 vs. 2x7 and PM10 deposition manual (6 vs. 8. Average values, as well as high concentration episodes (>98%thresholds are equally analysed and evaluated. The main conclusion is that there are so big differences between the years both in absolute values and relative sequence of valley-based and control groups that the analysed there years is not enough to make any final conclusion. For step-over frequencies, however valley-based towns have some advantage, possibly due to the valley-hill wind system.

  15. From the valley floor to the peaks: Stratigraphy and landscape evolution of the Alpine Lateglacial in the Kitzbühel Alps (Tyrol, Austria)

    Science.gov (United States)

    Dippenaar, Elijah; Reitner, Jürgen

    2017-04-01

    Our understanding of Alpine landscape evolution and more specifically, chronology of glacier activity during the Alpine Lateglacial (ALG; c. 19 - 11.7 ka) i.e. the timespan between the Würmian Pleniglacial (= Alpine Last Glacial Maximum; AlpLGM) and the beginning of the Holocene, is based on the evidence of only few areas in the Alps. In order to get a better understanding of glaciation and palaeoclimate during this phase, N-S and E-W transects are needed. The Kitzbühel Alps, which are currently not glaciated, span an area of 1700km2 and have peaks that reach c. 2400m a.s.l. They lie at the center of the Eastern Alps on the northern rim, which is more humid than the relatively dry central parts. A modern geological investigation of the ALG record is missing in the Kitzbühel Alps. In order to overcome this gap of knowledge and to gain a more complete understanding of the ALG landscape development, a pioneering study has been performed in the area of Langer Grund Valley, a tributary valley of the Kelchsau Valley. This was done through detailed field mapping, thereby describing the shape and sediment composition of Quaternary morphological features, such as moraines, landslides and rock glacier deposits. Sedimentary evidence of one short glacial advance and two glacial stadials were identified. In chronological order they were named the: Frommbach advance, the Arnbach (glacier) halt and the Küharn halt. Where possible, palaeoglaciers were constructed using ArcGIS. With the palaeoglaciers, equlibrium line altitudes (ELA) were calculated and compared to ELA values of known glacial stadials in an attempt to correlate the relative local stratigraphy to the Lateglacial stratigraphy. Four methods to calculate ELAs were used; Maximum Elevation of Lateral Moraines (MELM), Toe to Headwall Altitude Ratio (THAR), Area x Altitude (AA) and Accumulation Area Ratio (AAR). Furthermore, the glacial sedimentary sequence of the study area was compared to that of the Gschnitz Valley

  16. Late Glacial and Holocene gravity deposits in the Gulf of Lions deep basin, Western Mediterranean

    Science.gov (United States)

    Dennielou, B.; Bonnel, C.; Sultan, N.; Voisset, M.; Berné, S.; Beaudouin, C.; Guichard, F.; Melki, T.; Méar, Y.; Droz, L.

    2003-04-01

    Recent investigations in the Gulf of Lions have shown that complex gravity processes and deposits occurred in the deep basin since the last Glacial period. Besides the largest western Mediterranean turbiditic system, Petit-Rhône deep-sea fan (PRDSF), whose built-up started at the end of Pliocene, several sedimentary bodies can be distinguished: (1) The turbiditic Pyreneo-Languedocian ridge (PLR), at the outlet of the Sète canyon network, whose activity is strongly connected to the sea level and the connection of the canyons with the rivers. It surface shows long wave-length sediment waves, probably in relation with the turbiditic overspill. (2) An acoustically chaotic unit, filling the topographic low between the PRDSF and the PLR, the Lower Interlobe Unit. Possible source areas are the Sète canyon and/or the Marti Canyon. (3) An acoustically transparent unit, below the neofan, filling the same topographic low, the Western Transparent Unit, interpreted as a debris-flow. Recent sediment cores have shown that this sedimentary is composed of folded, laminated mud, both in its northern and southern fringes. (4) The Petit-Rhône neofan, a channelized turbiditic lobe resulting from the last avulsion of the Petit-Rhône turbiditic channel and composed of two units. The lower, acoustically chaotic facies unit, corresponding to an initial stage of the avulsion, similar to the HARP facies found on the Amazon fan. The upper, transparent, slightly bedded, channel-levee shaped unit, corresponding to the channelized stage of the avulsion. (5) Up to ten, Deglacial to Holocene, thin, fine sand layers, probably originating from shelf-break sand accumulations, through the Sète canyon network. (6) Giant scours, in the southern, distal part of the neofan, possibly linked to turbiditic overflow from the neo-channel, probably corresponding to channel-lobe transition zone features (Wynn et al. 2002). Recent investigations have shown no evidence of bottom current features.

  17. Glacial chronology and palaeoclimate in the Bystra catchment, Western Tatra Mountains (Poland) during the Late Pleistocene

    Science.gov (United States)

    Makos, Michał; Rinterknecht, Vincent; Braucher, Régis; Żarnowski, Michał

    2016-02-01

    Deglaciation chronology of the Bystra catchment (Western Tatra Mountains) has been reconstructed based on 10Be exposure age dating. Fourteen rock samples were collected from boulders located on three moraines that limit the horizontal extent of the LGM maximum advance and the Lateglacial recessional stage. The oldest preserved, maximum moraine was dated at 15.5 ± 0.8 ka, an age that could be explained more likely by post-depositional erosion of the moraine. Such scenario is supported by geomorphologic and palaeoclimatological evidence. The younger cold stage is represented by well-preserved termino-lateral moraine systems in the Kondratowa and Sucha Kasprowa valleys. The distribution of the moraine ridges in both valleys suggest a complex history of deglaciation of the area. The first Late-glacial re-advance (LG1) was followed by a cold oscillation (LG2), that occurred at around 14.0 ± 0.7-13.7 ± 1.2 ka. Glaciers during both stages had nearly the same horizontal extent, however, their thickness and geometry changed significantly, mainly due to local climatic conditions triggered by topography, controlling the exposition to solar radiation. The LG1 stage occurred probably during the pre-Bølling cold stage (Greenland Stadial 2.1a), however, the LG2 stage can be correlated with the cooling at around 14 ka during the Greenland Interstadial 1 (GI-1d - Older Dryas). This is the first chronological evidence of the Older Dryas in the Tatra Mountains. The ELA of the maximum Bystra glacier was located at 1480 m a.s.l. in accordance with the ELA in the High Tatra Mountains during the LGM. During the LG1 and LG2 stages, the ELA in the catchment rose up to 1520-1530 m a.s.l. and was located approximately 100-150 m lower than in the eastern part of the massif. Climate modelling results show that the Bystra glacier (maximum advance) could have advanced in the catchment when mean annual temperature was lower than today by 11-12 °C and precipitation was reduced by 40-60%. This

  18. California's restless giant: the Long Valley Caldera

    Science.gov (United States)

    Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae

    2014-01-01

    Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley Caldera had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil authorities with current information on the volcanic hazard at Long Valley and is prepared to give timely warnings of any impending eruption.

  19. Ground-water hydrology and glacial geology of the Kalamazoo area, Michigan

    Science.gov (United States)

    Deutsch, Morris; Vanlier, K.E.; Giroux, P.R.

    1960-01-01

    The Kalamazoo report area includes about 150 square miles of Kalamazoo County, Mich. The area is principally one of industry and commerce, although agriculture also is of considerable importance. It has a moderate and humid climate and lies within the Lake Michigan “snow belt”. Precipitation averages about 35 inches per year. Snowfall averages about 55 inches. The surface features of the area were formed during and since the glacial epoch and are classified as outwash plain, morainal highlands, and glaciated channels or drainageways. The area is formed largely on the remnants of an extensive outwash plain, which is breached by the Kalamazoo River in the northeastern part and is dissected elsewhere by several small tributaries to the river. Most of the land drained by these tributaries lies within the report area. A small portion of the southern part drains to the St. Joseph River. The Coldwater shale, which underlies the glacial deposits throughout the area, and the deeper bedrock formations are not tapped for water by wells and they have little or no potential for future development. Deposits of glacial drift, which are the source of water to all the wells in the area, have considerable potential for future development. These deposits range in thickness from about 40 feet along the Kalamazoo River to 350 feet where valleys were eroded in the bedrock surface. Permeable outwash and channel deposits are the sources of water for wells of large capacity. The moraines are formed dominantly by till of lower permeability which generally yields small supplies of water, but included sand and gravel beds of higher permeability yield larger supplies locally. The aquifers of the Kalamazoo area are recharged by infiltration of rainfall and snowmelt and by infiltration of surface waters induced by pumping of wells near the surface sources. Water pumped from most of the municipal well fields is replenished in part by such induced infiltration. Many of the industrial wells

  20. Response of spatial vegetation distribution in China to climate changes since the Last Glacial Maximum (LGM)

    Science.gov (United States)

    Wang, Siyang; Xu, Xiaoting; Shrestha, Nawal; Zimmermann, Niklaus E.; Tang, Zhiyao; Wang, Zhiheng

    2017-01-01

    Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present. PMID:28426780

  1. 7 CFR 58.730 - Filling containers.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filling containers. 58.730 Section 58.730 Agriculture... Procedures § 58.730 Filling containers. Hot fluid cheese from the cookers may be held in hotwells or hoppers... shall effectively measure the desired amount of product into the pouch or container in a sanitary manner...

  2. Selective filling of Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Noordegraaf, Danny; Sørensen, Thorkild

    2005-01-01

    A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre...

  3. GLOFs in the WOS: bibliometrics, geographies and global trends of research on glacial lake outburst floods (Web of Science, 1979-2016)

    Science.gov (United States)

    Emmer, Adam

    2018-03-01

    Research on glacial lake outburst floods (GLOFs) - specific low-frequency, high-magnitude floods originating in glacial lakes, including jökulhlaups - is well justified in the context of glacier ice loss and glacial lake evolution in glacierized areas all over the world. Increasing GLOF research activities, which are documented by the increasing number of published research items, have been observed in the past few decades; however, comprehensive insight into the GLOF research community, its global bibliometrics, geographies and trends in research is missing. To fill this gap, a set of 892 GLOF research items published in the Web of Science database covering the period 1979-2016 was analysed. General bibliometric characteristics, citations and references were analysed, revealing a certain change in the publishing paradigm over time. Furthermore, the global geographies of research on GLOFs were studied, focusing on (i) where GLOFs are studied, (ii) who studies GLOFs, (iii) the export of research on GLOFs and (iv) international collaboration. The observed trends and links to the challenges ahead are discussed and placed in a broader context.

  4. Glacial and volcanic evolution on Nevado Coropuna (Tropical Andes) based on cosmogenic 36Cl surface exposure dating

    Science.gov (United States)

    Úbeda, J.; Palacios, D.; Vázquez-Selém, L.

    2012-04-01

    We have reconstructed the evolution of the paleo-glaciers of the volcanic complex Nevado Coropuna (15°S, 72°W; 6377 m asl) through the interpretation and dating of geomorphological evidences. Surface exposure dating (SED) based on the accumulation of 36Cl on the surface of moraine boulders, polished bedrock and lava flows allowed: 1) to confirm that the presence of ice masses in the region dates back to >80ka; 2) to produce chronologies of glacial and volcanic phases for the last ~21 ka; and 3) to obtain evidences of the reactivation of volcanic activity after the Last Glacial Maximum. Bromley et al. (2009) presented 3He SED ages of 21 ka for moraine boulders on the Mapa Mayo valley, to the North of Nevado Coropuna. Our 36Cl SED SED for moraine boulders from the valleys on the NE sector of the volcanic complex suggest a maximum initial advance between 20 and 16 ka, followed by another expansion of similar extent at 12-11 ka. On the Southern slope of Nevado Coropuna, the 36Cl ages show a maximum initial advance that reaches to the level of the Altiplano at 14 ka, and a re-advance at ~10-9 ka BP. Other data show minor re-advances at 9 ka on the Northern slope and at 6 ka to the South of the volcanic complex. These minor positive pulses interrupted a fast deglaciation process during the Holocene as shown by two series of 36Cl SED from polished rock surfaces on successively higher altitudes along the valleys of rivers Blanco and Cospanja, to the SW and SE. Despite the global warming occuring since 20 ka, deduced from the record of sea surface paleo-temperature of the Galapago Islands (Lea et al, 2006), the evolution of the fresh-water plankton from Lake Titicaca (Fritz et al, 2007) is consistent with sustained glacial conditions until 10-9 ka as suggested by the present work. Exposure ages of three lava flows indicate a reactivation of the magmatic system as the paleo-glaciers abandonned the slopes. The eruptive activity migrated from the West, where we found a lava

  5. Simulating Glacial Outburst Lake Releases for Suicide Basin, Mendenhall Glacier, Juneau, Alaska

    Science.gov (United States)

    Jacobs, A. B.; Moran, T.; Hood, E. W.

    2017-12-01

    Glacial Lake outbursts from Suicide Basin are recent phenomenon first characterized in 2011. The 2014 event resulted in record river stage and moderate flooding on the Mendenhall River in Juneau. Recognizing that these events can adversely impact residential areas of Juneau's Mendenhall Valley, the Alaska-Pacific River Forecast Center developed a real-time modeling technique capable of forecasting the timing and magnitude of the flood-wave crest due to releases from Suicide Basin. The 2014 event was estimated at about 37,000 acre feet with water levels cresting within 36 hours from the time the flood wave hit Mendenhall Lake. Given the magnitude of possible impacts to the public, accurate hydrological forecasting is essential for public safety and Emergency Managers. However, the data needed to effectively forecast magnitudes of specific jökulhlaup events are limited. Estimating this event as related to river stage depended upon three variables: 1) the timing of the lag between Suicide Basin water level declines and the related rise of Mendenhall Lake, 2) continuous monitoring of Mendenhall Lake water levels, and 3) estimating the total water volume stored in Suicide Basin. Real-time modeling of the event utilized a Time of Concentration hydrograph with independent power equations representing the rising and falling limbs of the hydrograph. The initial accuracy of the model — as forecasted about 24 hours prior to crest — resulted in an estimated crest within 0.5 feet of the actual with a timing error of about six hours later than the actual crest.

  6. Raman spectra of filled carbon nanotubes

    International Nuclear Information System (INIS)

    Bose, S.M.; Behera, S.N.; Sarangi, S.N.; Entel, P.

    2004-01-01

    The Raman spectra of a metallic carbon nanotube filled with atoms or molecules have been investigated theoretically. It is found that there will be a three way splitting of the main Raman lines due to the interaction of the nanotube phonon with the collective excitations (plasmons) of the conduction electrons of the nanotube as well as its coupling with the phonon of the filling material. The positions and relative strengths of these Raman peaks depend on the strength of the electron-phonon interaction, phonon frequency of the filling atom and the strength of interaction of the nanotube phonon and the phonon of the filling atoms. Careful experimental studies of the Raman spectra of filled nanotubes should show these three peaks. It is also shown that in a semiconducting nanotube the Raman line will split into two and should be observed experimentally

  7. Small martian valleys: Pristine and degraded morphology

    International Nuclear Information System (INIS)

    Baker, V.R.; Partridge, J.B.

    1986-01-01

    The equatorial heavily cratered uplands of Mars are dissected by two classes of small valleys that are intimately associated in compound networks. Pristine valleys with steep valley walls preferentially occupy downstream portions of compound basins. Degraded valleys with eroded walls are laterally more extensive and have higher drainage densities than pristine valleys. Morphometric and crater-counting studies indicate that relatively dense drainage networks were emplaced on Mars during the heavy bombardment about 4.0 b.y. ago. Over a period of approximately 10 8 years, these networks were degraded and subsequently invaded by headwardly extending pristine valleys. The pristine valleys locally reactivated the compound networks, probably through sapping processes dependent upon high water tables. Fluvial activity in the heavily cratered uplands generally ceased approximately 3.8--3.9 b.y. ago, coincident with the rapid decline in cratering rates. The relict compound valleys on Mars are morphometrically distinct from most terrestrial drainage systems. The differences might be caused by a Martian valley formation episode characterized by hyperaridity, by inadequate time for network growth, by very permeable rock types, or by a combination of factors

  8. EPA Region 1 - Valley Depth in Meters

    Science.gov (United States)

    Raster of the Depth in meters of EPA-delimited Valleys in Region 1.Valleys (areas that are lower than their neighbors) were extracted from a Digital Elevation Model (USGS, 30m) by finding the local average elevation, subtracting the actual elevation from the average, and selecting areas where the actual elevation was below the average. The landscape was sampled at seven scales (circles of 1, 2, 4, 7, 11, 16, and 22 km radius) to take into account the diversity of valley shapes and sizes. Areas selected in at least four scales were designated as valleys.

  9. A landscape scale valley confinement algorithm: Delineating unconfined valley bottoms for geomorphic, aquatic, and riparian applications

    Science.gov (United States)

    David E. Nagel; John M. Buffington; Sharon L. Parkes; Seth Wenger; Jaime R. Goode

    2014-01-01

    Valley confinement is an important landscape characteristic linked to aquatic habitat, riparian diversity, and geomorphic processes. This report describes a GIS program called the Valley Confinement Algorithm (VCA), which identifies unconfined valleys in montane landscapes. The algorithm uses nationally available digital elevation models (DEMs) at 10-30 m resolution to...

  10. West Valley Demonstration Project, West Valley, New York: Annual report

    International Nuclear Information System (INIS)

    1989-01-01

    Under the West Valley Demonstration Project Act, Public Law 96-368, liquid high-level radioactive waste stored at the Western New York Nuclear Services Center, West Valley, New York, that resulted from spent nuclear fuel reprocessing operations conducted between 1966 and 1972, is to be solidified in borosilicate glass and transported to a federal repository for geologic disposal. A major milestone was reached in May 1988 when the Project began reducing the volume of the liquid high-level waste. By the end of 1988, approximately 15 percent of the initial inventory had been processed into two waste streams. The decontaminated low-level liquid waste is being solidified in cement. The high-level waste stream is being stored in an underground tank pending its incorporation into borosilicate glass. Four tests of the waste glass melter system were completed. These tests confirmed equipment operability, control system reliability, and provided samples of waste glass for durability testing. In mid-1988, the Department validated an integrated cost and schedule plan for activities required to complete the production of the waste borosilicate glass. Design of the radioactive Vitrification Facility continued

  11. Middle Pleistocene infill of Hinkley Valley by Mojave River sediment and associated lake sediment: Depositional architecture and deformation by strike-slip faults

    Science.gov (United States)

    Miller, David; Haddon, Elizabeth; Langenheim, Victoria; Cyr, Andrew J.; Wan, Elmira; Walkup, Laura; Starratt, Scott W.

    2018-01-01

    Hinkley Valley in the Mojave Desert, near Barstow about 140 km northeast of Los Angeles and midway between Victorville Valley and the Lake Manix basin, contains a thick sedimentary sequence delivered by the Mojave River. Our study of sediment cores drilled in the valley indicates that Hinkley Valley was probably a closed playa basin with stream inflow from four directions prior to Mojave River inflow. The Mojave River deposited thick and laterally extensive clastic wedges originating from the southern valley that rapidly filled much of Hinkley Valley. Sedimentary facies representing braided stream, wetland, delta, and lacustrine depositional environments all are found in the basin fill; in some places, the sequence is greater than 74 m (245 ft) thick. The sediment is dated in part by the presence of the ~631 ka Lava Creek B ash bed low in the section, and thus represents sediment deposition after Victorville basin was overtopped by sediment and before the Manix basin began to be filled. Evidently, upstream Victorville basin filled with sediment by about 650 ka, causing the ancestral Mojave River to spill to the Harper and Hinkley basins, and later to Manix basin.Initial river sediment overran wetland deposits in many places in southern Hinkley Valley, indicating a rapidly encroaching river system. These sediments were succeeded by a widespread lake (“blue” clay) that includes the Lava Creek B ash bed. Above the lake sediment lies a thick section of interlayered stream sediment, delta and nearshore lake sediment, mudflat and/or playa sediment, and minor lake sediment. This stratigraphic architecture is found throughout the valley, and positions of lake sediment layers indicate a successive northward progression in the closed basin. A thin overlapping sequence at the north end of the valley contains evidence for a younger late Pleistocene lake episode. This late lake episode, and bracketing braided stream deposits of the Mojave River, indicate that the river

  12. The Pocatello Valley, Idaho, earthquake

    Science.gov (United States)

    Rogers, A. M.; Langer, C.J.; Bucknam, R.C.

    1975-01-01

    A Richter magnitude 6.3 earthquake occurred at 8:31 p.m mountain daylight time on March 27, 1975, near the Utah-Idaho border in Pocatello Valley. The epicenter of the main shock was located at 42.094° N, 112.478° W, and had a focal depth of 5.5 km. This earthquake was the largest in the continental United States since the destructive San Fernando earthquake of February 1971. The main shock was preceded by a magnitude 4.5 foreshock on March 26. 

  13. Radwaste challenge at Beaver Valley

    International Nuclear Information System (INIS)

    Anon.

    1984-01-01

    Duquesne Light Company met the problem of accumulating low-level radioactive waste at its Beaver Valley nuclear plant with an aggressive program to reduce the quantity of contaminated material and demonstrate that the plant was improving its radiological protection. There was also an economic incentive to reduce low-level wastes. The imaginative campaign involved workers in the reduction effort through training and the adoption of practical approaches to reducing the amount of material exposed to radiation that include sorting trash by radiation level and a compacting system. 4 figures

  14. The Owens Valley Millimeter Array

    International Nuclear Information System (INIS)

    Padin, S.; Scott, S.L.; Woody, D.P.; Scoville, N.Z.; Seling, T.V.

    1991-01-01

    The telescopes and signal processing systems of the Owens Valley Millimeter Array are considered, and improvements in the sensitivity and stability of the instrument are characterized. The instrument can be applied to map sources in the 85 to 115 GHz and 218 to 265 GHz bands with a resolution of about 1 arcsec in the higher frequency band. The operation of the array is fully automated. The current scientific programs for the array encompass high-resolution imaging of protoplanetary/protostellar disk structures, observations of molecular cloud complexes associated with spiral structure in nearby galaxies, and observations of molecular structures in the nuclei of spiral and luminous IRAS galaxies. 9 refs

  15. Methane emissions from a high arctic valley: findings and challenges

    DEFF Research Database (Denmark)

    Mastepanov, Mikhail; Sigsgaard, Charlotte; Ström, Lena

    2008-01-01

    Wet tundra ecosystems are well-known to be a significant source of atmospheric methane. With the predicted stronger effect of global climate change on arctic terrestrial ecosystems compared to lower-latitudes, there is a special obligation to study the natural diversity and the range of possible...... feedback effects on global climate that could arise from Arctic tundra ecosystems. One of the prime candidates for such a feedback mechanism is a potential change in the emissions of methane. Long-term datasets on methane emissions from high arctic sites are almost non-existing but badly needed...... for analyses of controls on interannual and seasonal variations in emissions. To help fill this gap we initiated a measurement program in a productive high arctic fen in the Zackenberg valley, NE Greenland. Methane flux measurements have been carried out at the same location since 1997. Compared...

  16. STEM education for teachers in the Rio Grande Valley

    Science.gov (United States)

    Ries, Judit Gyorgyey; Baguio, Margaret R.

    2015-11-01

    We have worked with elementary and middle school teachers in the Rio Grande Valley for the last 10 years bringing Earth and Space Science themed workshops to underserved areas of Texas. The Texas curriculum was also changed to include Astronomy and Space Science requirement in the tests students need to take to prove their academic preparedness. The teachers worked through a variety of inquiry-based, hands-on activities after a short presentation on the background science. In order to evaluate our effectiveness, we have asked the teachers to take pre- and post-workshop tests, and we asked them to fill out a self-reflective survey. We will report on our experiences, what works best with the teachers, and in what areas we still have a long way to go.This work was supported by various NASA education grants and Cooperative agreements, as well as grants provided by the Texas Space Grant Consortium.

  17. High-resolution three-dimensional imaging and analysis of rock falls in Yosemite valley, California

    Science.gov (United States)

    Stock, Gregory M.; Bawden, G.W.; Green, J.K.; Hanson, E.; Downing, G.; Collins, B.D.; Bond, S.; Leslar, M.

    2011-01-01

    We present quantitative analyses of recent large rock falls in Yosemite Valley, California, using integrated high-resolution imaging techniques. Rock falls commonly occur from the glacially sculpted granitic walls of Yosemite Valley, modifying this iconic landscape but also posing signifi cant potential hazards and risks. Two large rock falls occurred from the cliff beneath Glacier Point in eastern Yosemite Valley on 7 and 8 October 2008, causing minor injuries and damaging structures in a developed area. We used a combination of gigapixel photography, airborne laser scanning (ALS) data, and ground-based terrestrial laser scanning (TLS) data to characterize the rock-fall detachment surface and adjacent cliff area, quantify the rock-fall volume, evaluate the geologic structure that contributed to failure, and assess the likely failure mode. We merged the ALS and TLS data to resolve the complex, vertical to overhanging topography of the Glacier Point area in three dimensions, and integrated these data with gigapixel photographs to fully image the cliff face in high resolution. Three-dimensional analysis of repeat TLS data reveals that the cumulative failure consisted of a near-planar rock slab with a maximum length of 69.0 m, a mean thickness of 2.1 m, a detachment surface area of 2750 m2, and a volume of 5663 ?? 36 m3. Failure occurred along a surfaceparallel, vertically oriented sheeting joint in a clear example of granitic exfoliation. Stress concentration at crack tips likely propagated fractures through the partially attached slab, leading to failure. Our results demonstrate the utility of high-resolution imaging techniques for quantifying far-range (>1 km) rock falls occurring from the largely inaccessible, vertical rock faces of Yosemite Valley, and for providing highly accurate and precise data needed for rock-fall hazard assessment. ?? 2011 Geological Society of America.

  18. Integrated U-Pb zircon and palynological/palaeofloristic age determinations of a Bashkirian palaeofjord fill, Quebrada Grande (Western Argentina)

    Science.gov (United States)

    Valdez Buso, Victoria; di Pasquo, Mercedes; Milana, Juan Pablo; Kneller, Benjamin; Fallgatter, Claus; Junior, Farid Chemale; Gomes Paim, Paulo Sérgio

    2017-01-01

    This work presents a new age framework for the main Bashkirian glacio-eustatic transgression in Argentina, including the first absolute age for the Jejenes Formation, San Juan Province, based on radiometric dating of a crystal-rich tuff, supported by palynological and palaeofloristic studies, and presented within a revised palaeogeographic setting. The Jejenes Formation represents the glacial to postglacial fill of the Quebrada Grande palaeofjord carved in the Eastern Precordillera. The succession has been subdivided into five stages, the youngest of which suggests a previously unrecognised glacial event for this locality. Six productive levels for palynology were found within proglacial strata, and in the base and top of the succeeding interglacial stage. Palynoassemblages are characterized by poorly preserved trilete spores and monosaccate pollen grains along with a large amount of terrestrial phytoclasts. Main species indicating the Raistrickia densa-Convolutispora muriornata SubZone (DMa SZ) are Vallatisporites ciliaris, Cristatisporites rollerii, C. stellatus, C. chacoparanensis, C. inconstans and monosaccates such as Circumplicatipollis plicatus. This DMa SZ is estimated as Serpukhovian/Bashkirian and characterizes the glacial-related Guandacol Formation and equivalents units of the western Paganzo Basin. A tuffaceous level in the proglacial unit, bearing platyspermic seeds, plant remains and palynomorphs, yielded first-cycle volcanic zircons that were analysed by SHRIMP. An absolute age of 321.3 ± 5.3 Ma confirms a Bashkirian age for the main postglacial transgression in the Paganzo Basin, and offers a novel calibration for the palynoassemblages of DMa SZ that occurs elsewhere in Western Argentina.

  19. Numerical investigations of subglacial hydrology as a direct and indirect driver of glacial erosion

    OpenAIRE

    Beaud, Flavien

    2017-01-01

    Glaciers shape high altitude and latitude landscapes in numerous ways. Erosion associated with glacial processes can limit the average height of mountain ranges, while creating the greatest relief on Earth and shaping the highest mountain peaks, but glaciers can also shield pre-existing topography. Glacial erosion processes, though still enigmatic, are central to the evolution of landscapes, particularly since the onset of the Pleistocene. Glacial erosion comprises three fundamental processes...

  20. Holocene evolution of a drowned melt-water valley in the Danish Wadden Sea

    DEFF Research Database (Denmark)

    Pedersen, Jørn Bjarke Torp; Svinth, Steffen; Bartholdy, Jesper

    2009-01-01

    Cores from the salt marshes along the drowned melt-water valley of river Varde Å in the Danish Wadden Sea have been dated and analysed (litho- and biostratigraphically) to reconstruct the Holocene geomorphologic evolution and relative sea level history of the area. The analysed cores cover...... the total post-glacial transgression, and the reconstructed sea level curve represents the first unbroken curve of this kind from the Danish Wadden Sea, including all phases from the time where sea level first reached the Pleistocene substrate of the area. The sea level has been rising from - 12 m below...... the present level at c. 8400 cal yr BP, interrupted by two minor drops of sea level rise, and the Holocene sequence consists in most places of clay atop...

  1. Text-Filled Stacked Area Graphs

    DEFF Research Database (Denmark)

    Kraus, Martin

    2011-01-01

    -filled stacked area graphs; i.e., graphs that feature stacked areas that are filled with small-typed text. Since these graphs allow for computing the text layout automatically, it is possible to include large amounts of textual detail with very little effort. We discuss the most important challenges and some...... solutions for the design of text-filled stacked area graphs with the help of an exemplary visualization of the genres, publication years, and titles of a database of several thousand PC games....

  2. Droplet Measurement below Single-Layer Grid Fill

    Directory of Open Access Journals (Sweden)

    Vitkovic Pavol

    2016-01-01

    Full Text Available The main part of the heat transfer in a cooling tower is in a fill zone. This one is consist of a cooling fill. For the cooling tower is used a film fill or grid fill or splash fill in the generally. The grid fill has lower heat transfer performance like film fill usually. But their advantage is high resistance to blockage of the fill. The grid fill is consisted with independent layers made from plastic usually. The layers consist of several bars connected to the different shapes. For experiment was used the rhombus shape. The drops diameter was measured above and below the Grid fill.

  3. Glacial hazards: communicating the science and managing the risk

    Science.gov (United States)

    Reynolds, J. M.

    2009-04-01

    The recession of glaciers worldwide has received huge media coverage over the last few years in association with the issue of climate change. Young people at schools and colleges are increasingly aware of the environmental pressures due to ‘global warming'. Yet simultaneously, there appears to be an increasing move away from studying science both at pre-university and undergraduate levels. One of the oft cited reasons is that students cannot see the application of the subjects being taught them. Glacial hazards are one of the most obvious adverse effects of climate change, with many, often poor, communities in remote mountain areas being the most affected by frequently devastating Glacial Lake Outburst Floods (GLOFs). When students are exposed to examples of these hazards and the science behind them, many become enthused by the subject and want to study it further. There has been a huge increase in the number of students selecting projects on glacial hazards as well as a large increase in the number of institutions offering to teach modules on this subject. In an effort to provide a basic visualisation, Peter Kennett has taken the principle of GLOFs and developed a cheap but highly visual demonstration of the potentially devastating effect of melting ice within a moraine leading to subsidence and subsequent dam failure. This is available on www.earthlearningidea.com as ‘Dam burst danger - modelling the collapse of a natural dam in the mountains - and the disaster that might follow'. Furthermore, the methods by which glacial hazards are assessed provide excellent applications of geophysics, geology, geography (physical and Human), engineering, mathematics, and glaciology. By exploring the potential vulnerability of communities downstream, the applications can be extended to include sociology, economics, geopolitics and even psychology. Glacial hazards have been the subject of presentations to the Earth Science Teachers Association (ESTA) in the UK to demonstrate

  4. Valley-dependent band structure and valley polarization in periodically modulated graphene

    Science.gov (United States)

    Lu, Wei-Tao

    2016-08-01

    The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

  5. Sustainable agricultural development in inland valleys

    NARCIS (Netherlands)

    Zwart, S.J.

    2018-01-01

    The inland valley in Africa are common landscapes that have favorable conditions for agricultural production. Compared to the surrounding uplands they are characterized by a relatively high and secure water availability and high soil fertility levels. Inland valleys thus have a high agricultural

  6. Valley dependent transport in graphene L junction

    Science.gov (United States)

    Chan, K. S.

    2018-05-01

    We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

  7. Climate Stability: Pathway to understand abrupt glacial climate shifts

    Science.gov (United States)

    Zhang, X.; Knorr, G.; Barker, S.; Lohmann, G.

    2017-12-01

    Glacial climate is marked by abrupt, millennial-scale climate changes known as Dansgaard-Oeschger (DO) cycles that have been linked to variations in the Atlantic meridional overturning circulation (AMOC). The most pronounced stadial coolings, Heinrich Stadials (HSs), are associated with massive iceberg discharges to the North Atlantic. This motivates scientists to consider that the North Atlantic freshwater perturbations is a common trigger of the associated abrupt transitions between weak and strong AMOC states. However, recent studies suggest that the Heinrich ice-surging events are triggered by ocean subsurface warming associated with an AMOC slow-down. Furthermore, the duration of ice-rafting events does not systematically coincide with the beginning and end of the pronounced cold conditions during HSs. In this context, we show that both, changes in atmospheric CO2 and ice sheet configuration can provide important control on the stability of the AMOC, using a coupled atmosphere-ocean model. Our simulations reveal that gradual changes in Northern Hemisphere ice sheet height and atmospheric CO2 can act as a trigger of abrupt glacial/deglacial climate changes. The simulated global climate responses—including abrupt warming in the North Atlantic, a northward shift of the tropical rain belts, and Southern Hemisphere cooling related to the bipolar seesaw—are generally consistent with empirical evidence. We further find that under a delicate configuration of atmospheric CO2 and ice sheet height the AMOC can be characterized by a self-oscillation (resonance) feature (Hopf Bifucation) with a 1000-year cycle that is comparable with observed small DO events during the MIS 3. This provides an alternative explanation for millennial-scale DO variability during glacial periods.

  8. Predicting future glacial lakes in Austria using different modelling approaches

    Science.gov (United States)

    Otto, Jan-Christoph; Helfricht, Kay; Prasicek, Günther; Buckel, Johannes; Keuschnig, Markus

    2017-04-01

    Glacier retreat is one of the most apparent consequences of temperature rise in the 20th and 21th centuries in the European Alps. In Austria, more than 240 new lakes have formed in glacier forefields since the Little Ice Age. A similar signal is reported from many mountain areas worldwide. Glacial lakes can constitute important environmental and socio-economic impacts on high mountain systems including water resource management, sediment delivery, natural hazards, energy production and tourism. Their development significantly modifies the landscape configuration and visual appearance of high mountain areas. Knowledge on the location, number and extent of these future lakes can be used to assess potential impacts on high mountain geo-ecosystems and upland-lowland interactions. Information on new lakes is critical to appraise emerging threads and potentials for society. The recent development of regional ice thickness models and their combination with high resolution glacier surface data allows predicting the topography below current glaciers by subtracting ice thickness from glacier surface. Analyzing these modelled glacier bed surfaces reveals overdeepenings that represent potential locations for future lakes. In order to predict the location of future glacial lakes below recent glaciers in the Austrian Alps we apply different ice thickness models using high resolution terrain data and glacier outlines. The results are compared and validated with ice thickness data from geophysical surveys. Additionally, we run the models on three different glacier extents provided by the Austrian Glacier Inventories from 1969, 1998 and 2006. Results of this historical glacier extent modelling are compared to existing glacier lakes and discussed focusing on geomorphological impacts on lake evolution. We discuss model performance and observed differences in the results in order to assess the approach for a realistic prediction of future lake locations. The presentation delivers

  9. Pyrite sulfur isotopes reveal glacial-interglacial environmental changes

    Science.gov (United States)

    Pasquier, Virgil; Sansjofre, Pierre; Rabineau, Marina; Revillon, Sidonie; Houghton, Jennifer; Fike, David A.

    2017-06-01

    The sulfur biogeochemical cycle plays a key role in regulating Earth’s surface redox through diverse abiotic and biological reactions that have distinctive stable isotopic fractionations. As such, variations in the sulfur isotopic composition (δ34S) of sedimentary sulfate and sulfide phases over Earth history can be used to infer substantive changes to the Earth’s surface environment, including the rise of atmospheric oxygen. Such inferences assume that individual δ34S records reflect temporal changes in the global sulfur cycle; this assumption may be well grounded for sulfate-bearing minerals but is less well established for pyrite-based records. Here, we investigate alternative controls on the sedimentary sulfur isotopic composition of marine pyrite by examining a 300-m drill core of Mediterranean sediments deposited over the past 500,000 y and spanning the last five glacial-interglacial periods. Because this interval is far shorter than the residence time of marine sulfate, any change in the sulfur isotopic record preserved in pyrite (δ34Spyr) necessarily corresponds to local environmental changes. The stratigraphic variations (>76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level and temperature changes. In this case, the dominant control appears to be glacial-interglacial variations in sedimentation rates. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records, especially associated with intervals of substantial sea level change. This work provides an important perspective on the origin of variability in such records and suggests meaningful paleoenvironmental information can be derived from pyrite δ34S records.

  10. Greenland's glacial fjords and their role in regional biogeochemical dynamics.

    Science.gov (United States)

    Crosby, J.; Arndt, S.

    2017-12-01

    Greenland's coastal fjords serve as important pathways that connect the Greenland Ice Sheet (GrIS) and the surrounding oceans. They export seasonal glacial meltwater whilst being significant sites of primary production. These fjords are home to some of the most productive ecosystems in the world and possess high socio-economic value via fisheries. A growing number of studies have proposed the GrIS as an underappreciated yet significant source of nutrients to surrounding oceans. Acting as both transfer routes and sinks for glacial nutrient export, fjords have the potential to act as significant biogeochemical processors, yet remain underexplored. Critically, an understanding of the quantitative contribution of fjords to carbon and nutrient budgets is lacking, with large uncertainties associated with limited availability of field data and the lack of robust upscaling approaches. To close this knowledge gap we developed a coupled 2D physical-biogeochemical model of the Godthåbsfjord system, a sub-Arctic sill fjord in southwest Greenland, to quantitatively assess the impact of nutrients exported from the GrIS on fjord primary productivity and biogeochemical dynamics. Glacial meltwater is found to be a key driver of fjord-scale circulation patterns, whilst tracer simulations reveal the relative nutrient contributions from meltwater-driven upwelling and meltwater export from the GrIS. Hydrodynamic circulation patterns and freshwater transit times are explored to provide a first understanding of the glacier-fjord-ocean continuum, demonstrating the complex pattern of carbon and nutrient cycling at this critical land-ocean interface.

  11. Glacial greenhouse-gas fluctuations controlled by ocean circulation changes.

    Science.gov (United States)

    Schmittner, Andreas; Galbraith, Eric D

    2008-11-20

    Earth's climate and the concentrations of the atmospheric greenhouse gases carbon dioxide (CO(2)) and nitrous oxide (N(2)O) varied strongly on millennial timescales during past glacial periods. Large and rapid warming events in Greenland and the North Atlantic were followed by more gradual cooling, and are highly correlated with fluctuations of N(2)O as recorded in ice cores. Antarctic temperature variations, on the other hand, were smaller and more gradual, showed warming during the Greenland cold phase and cooling while the North Atlantic was warm, and were highly correlated with fluctuations in CO(2). Abrupt changes in the Atlantic meridional overturning circulation (AMOC) have often been invoked to explain the physical characteristics of these Dansgaard-Oeschger climate oscillations, but the mechanisms for the greenhouse-gas variations and their linkage to the AMOC have remained unclear. Here we present simulations with a coupled model of glacial climate and biogeochemical cycles, forced only with changes in the AMOC. The model simultaneously reproduces characteristic features of the Dansgaard-Oeschger temperature, as well as CO(2) and N(2)O fluctuations. Despite significant changes in the land carbon inventory, CO(2) variations on millennial timescales are dominated by slow changes in the deep ocean inventory of biologically sequestered carbon and are correlated with Antarctic temperature and Southern Ocean stratification. In contrast, N(2)O co-varies more rapidly with Greenland temperatures owing to fast adjustments of the thermocline oxygen budget. These results suggest that ocean circulation changes were the primary mechanism that drove glacial CO(2) and N(2)O fluctuations on millennial timescales.

  12. Beaver assisted river valley formation

    Science.gov (United States)

    Westbrook, Cherie J.; Cooper, D.J.; Baker, B.W.

    2011-01-01

    We examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in-channel beaver dams. Our data show a 1.7-m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient-rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de-watered following the dam breach by high stream flows, protecting the deposited sediment from future re-mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re-occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938. ?? 2010 John Wiley & Sons, Ltd.

  13. Denudation of the continental shelf between Britain and France at the glacial-interglacial timescale.

    Science.gov (United States)

    Mellett, Claire L; Hodgson, David M; Plater, Andrew J; Mauz, Barbara; Selby, Ian; Lang, Andreas

    2013-12-01

    palaeovalley-fills that are preserved as a strath terrace. The data presented here reveal a composite erosional and depositional record that has undergone a high degree of reworking over multiple sea-level cycles leading to the preferential preservation of sediments associated with the most recent glacial-interglacial period.

  14. CRYOGENESIS AND GEODYNAMICS OF ICING VALLEYS

    Directory of Open Access Journals (Sweden)

    V. R. Alekseyev

    2015-01-01

    Full Text Available Due to local groundwater seeping and freezing in layers that accumulate over each other and create large ice clusters on the ground surface, specific conditions of energy and mass transfer are created in the atmosphere–soil–lithosphere system. In winter, the vertical temperature distribution curve is significantly deformed due to heat emission from the water layer above the ice cover during its freezing, and a thermocline is thus formed. Deformation of the temperature curve is gradually decreasing in size downward the profile and decays at the interface of frozen and thaw rocks. Values and numbers of temperature deviations from a 'normal' value depend on heat reserves of aufeis water and the number of water seeps/discharges at a given location. The production of the thermocline alters freezing conditions for underlying ground layers and changes the mechanism of ice saturation, thus leading to formation of two-layer ice-ground complexes (IGC. IGCs are drastically different from cryogenic formations in the neighbouring sections of the river valley. Based on genetic characteristics and the ratios of components in the surface and subsurface layers, seven types of aufeis IGCs are distinguished: massive-segregation, cement-basal, layered-segregation, basal-segregation, vacuum-filtration, pressure-injection, and fissure-vein. Annual processes of surface and subsurface icing and ice ablation are accompanied by highly hazardous geodynamic phenomena, such as winter flooding, layered water freezing, soil heaving/pingo, thermokarst and thermal erosion. Combined, these processes lead to rapid and often incidental reconfigurations of the surface and subsurface runoff channels, abrupt uplifting and subsiding of the ground surface, decompaction and 'shaking-up' of seasonally freezing/thawing rocks, thereby producing exceptionally unfavourable conditions for construction and operation of engineering structures.Formation and development of river networks are

  15. Last Glacial vegetation and climate change in the southern Levant

    Science.gov (United States)

    Miebach, Andrea; Chen, Chunzhu; Litt, Thomas

    2015-04-01

    Reconstructing past climatic and environmental conditions is a key task for understanding the history of modern mankind. The interaction between environmental change and migration processes of the modern Homo sapiens from its source area in Africa into Europe is still poorly understood. The principal corridor of the first human dispersal into Europe and also later migration dynamics crossed the Middle East. Therefore, the southern Levant is a key area to investigate the paleoenvironment during times of human migration. In this sense, the Last Glacial (MIS 4-2) is particularly interesting to investigate for two reasons. Firstly, secondary expansions of the modern Homo sapiens are expected to occur during this period. Secondly, there are ongoing discussions on the environmental conditions causing the prominent lake level high stand of Lake Lisan, the precursor of the Dead Sea. This high stand even culminated in the merging of Lake Lisan and Lake Kinneret (Sea of Galilee). To provide an independent proxy for paleoenvironmental reconstructions in the southern Levant during the Last Glacial, we investigated pollen assemblages of the Dead Sea/Lake Lisan and Lake Kinneret. Located at the Dead Sea Transform, the freshwater Lake Kinneret is nowadays connected via the Jordan with the hypersaline Dead Sea, which occupies Earth's lowest elevation on land. The southern Levant is a transition area of three different vegetation types. Therefore, also small changes in the climate conditions effect the vegetation and can be registered in the pollen assemblage. In contrast to the Holocene, our preliminary results suggest another vegetation pattern during the Last Glacial. The vegetation belt of the fragile Mediterranean biome did no longer exist in the vicinity of Lake Kinneret. Moreover, the vegetation was rather similar in the whole study area. A steppe vegetation with dwarf shrubs, herbs, and grasses predominated. Thermophilous elements like oaks occurred in limited amounts. The

  16. PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

    Science.gov (United States)

    Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

  17. Geohydrology and water quality of the stratified-drift aquifers in Upper Buttermilk Creek and Danby Creek Valleys, Town of Danby, Tompkins County, New York

    Science.gov (United States)

    Miller, Todd S.

    2015-11-20

    In 2006, the U.S. Geological Survey, in cooperation with the Town of Danby and the Tompkins County Planning Department, began a study of the stratified-drift aquifers in the upper Buttermilk Creek and Danby Creek valleys in the Town of Danby, Tompkins County, New York. In the northern part of the north-draining upper Buttermilk Creek valley, there is only one sand and gravel aquifer, a confined basal unit that overlies bedrock. In the southern part of upper Buttermilk Creek valley, there are as many as four sand and gravel aquifers, two are unconfined and two are confined. In the south-draining Danby Creek valley, there is an unconfined aquifer consisting of outwash and kame sand and gravel (deposited by glacial meltwaters during the late Pleistocene Epoch) and alluvial silt, sand, and gravel (deposited by streams during the Holocene Epoch). In addition, throughout the study area, there are several small local unconfined aquifers where large tributaries deposited alluvial fans in the valley.

  18. Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

    Directory of Open Access Journals (Sweden)

    Woronko Barbara

    2015-06-01

    Full Text Available We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.

  19. Coring of Karakel’ Lake sediments (Teberda River valley and prospects for reconstruction of glaciation and Holocene climate history in the Caucasus

    Directory of Open Access Journals (Sweden)

    O. N. Solomina

    2013-01-01

    Full Text Available Lacustrine sediments represent an important data source for glacial and palaeoclimatic reconstructions. Having a number of certain advantages, they can be successfully used as a means of specification of glacier situation and age of moraine deposits, as well as a basis for detailed climatic models of the Holocene. The article focuses on the coring of sediments of Lake Kakakel (Western Caucasus that has its goal to clarify the Holocene climatic history for the region, providing the sampling methods, lithologic description of the sediment core, obtained radiocarbon dating and the element composition of the sediments. The primary outlook over the results of coring of the sediments of the Lake Karakyol helped to reconsider the conventional opinion on the glacial fluctuations in the valley of Teberda and to assume the future possibility for high-definition palaeoclimatic reconstruction for Western Caucasus.

  20. Dural sinus filling defect: intrasigmoid encephalocele

    Science.gov (United States)

    Karatag, Ozan; Cosar, Murat; Kizildag, Betul; Sen, Halil Murat

    2013-01-01

    Filling defects of dural venous sinuses are considered to be a challenging problem especially in case of symptomatic patients. Many lesions have to be ruled out such as sinus thrombosis, arachnoid granulations and tumours. Encephalocele into dural sinus is also a rare cause of these filling defects of dural sinuses. Here, we report an extremely rare case with spontaneous occult invagination of temporal brain tissue into the left sigmoid sinus and accompanying cerebellar ectopia. PMID:24311424

  1. LATE GLACIAL AND HOLOCENE ENVIRONMENTAL CHANGE INFERRED FROM THE PÁRAMO OF CAJANUMA IN THE PODOCARPUS NATIONAL PARK, SOUTHERN ECUADOR

    Directory of Open Access Journals (Sweden)

    ANDREA VILLOTA

    2014-12-01

    Full Text Available To reconstruct the environmental history including vegetation, fire and climate dynamics, from the Cajanuma valley area ( 3285 m elevation in the Podocarpus National Park, southern Ecuador , we address the following major research question: (1 How did the mountain vegetation developed during the late Glacial and Holocene? (2 Did fire played an important control on the vegetation change and was it natural or of anthropogenic origin?. Palaeoenvironmental changes were investigated using multiple proxies such as pollen, spores, charcoal analyses and radiocarbon dating. Pollen data indicated that during the late Glacial and transition to the early Holocene (ca. 16 000-10 500 cal yr BP herb páramo was the main vegetation type around the study area, while subpáramo and mountain rainforest were scarcely represented. The early and mid-Holocene (ca. 10 500 to 5600 cal yr BP is marked by high abundance of páramo during the early Holocene followed by a slight expansion of mountain forest during the mid-Holocene. During the mid- to late Holocene (ca. 5600-1200 cal yr BP there is a significant presence of páramo and subpáramo while Lower Mountain Forest decreased substantially, although, Upper Mountain Forest remained relatively stable during this period. The late Holocene, from ca. 1200 cal yr BP to present, was characterized by páramo; however, mountain forest and subpáramo presented significantly abundance compared to the previous periods. Fires became frequent since the late Holocene. The marked increased local and regional fire intensity during the wetter late Holocene strongly suggests that were of anthropogenic origin. During the late Glacial and early Holocene, the upper forest line was located at low elevations; but shifted slightly upslope to higher elevations during the mid-Holocene.

  2. Variaciones glaciales durante el Holoceno en Patagonia Central, Aisén, Chile: evidencias geomorfológicas Holocene glacial variations in Central Patagonia, Aisén, Chile: geomorphological evidences

    Directory of Open Access Journals (Sweden)

    María Mardones

    2011-07-01

    en la temperatura y precipitación atmosférica.During the Holocene, the patagonian glaciers were characterized by geomorphologically registered advances and retreats. This paper presents the geomorphological evolution and evidences of Holocene glacial advances within a segment in Central Patagonia Cordillera. This area will be used as a reference for studying the postglacial paleoclimatic evolution in the southernmost part of South America. The study area is the río Blanco basin (45°30'S, located in Central Patagonia (Aisén Region, Chile. Radiometric dating of organic sediments, within terminal moraines, provides preliminary data of two glacial advances. The first one is represented by the Lake Elizalde frontal moraine, which yielded a 14C age of 9.370±50 years BP (10,700 to 10,480 cal. yr BP. According to this chronological age, this glacial event took place in the Early Holocene. This glacial advance, being 100 to 200 years older than that observed immediately south of the study area, on the eastern edge of General Carrera Lake (or Buenos Aires Lake, in Argentina and approximately 100 years younger than the event recorded in the Puerto Banderas I moraine (Argentino Lake, 50°S. These results show that the behavior patterns of the Central Patagonia glaciers differ from that observed both in the Lake District (41°S, Chile and in the Magallanes District (54°S, Chile, where there are no traces of glacial readvancement recorded during the Early Holocene. After a major retreat to the west, a more recent glacial advance occurred in the Quetro river valley (a tributary river of the Blanco river, at an age prior to 2.250±40 BP (2.340 to 2.150 cal. yr BP, comparable to the cold stage of the Middle Neoglacial, interpreted to have occurred in different parts of Patagonia. Confronting these results with previously published pollen records, we postulate that the cause of both glacier fluctuations are regional variations in the atmospheric temperature and precipitations.

  3. Glacial sequence stratigraphy reveal the Weichselian glacial history of the SE sector of the Eurasian Ice Sheet

    Science.gov (United States)

    Räsänen, Matti

    2016-04-01

    Reconstructions of the last Weichselian glacial cycle 117,000-11,700 years (kyr) ago propose that S Finland, adjacent Russia and the Baltic countries in the SE sector of the Eurasian Ice Sheet (EIS), were glaciated during the Middle Weichselian time [marine isotope stage (MIS) 4, 71-57 kyr ago] and that this glaciation was preceded in S Finland by an Early Weichselian interstadial (MIS 5c, 105-93 kyr ago) with pine forest. Here glacial sequence stratigraphy (Powell and Cooper 2002) is applied to isolated Late Pleistocene onshore outcrop sections in S Finland. The analysed sedimentary records have traditionally been investigated, interpreted and published separately by different authors without an attempt to a methodologically more systematic survey. By putting new field data and old observations into a regional sequence stratigraphic framework it is shown how previously unnoticed regularities can be found in the lithofacies and fossil successions. It is shown that the proposed Middle Weichselian glaciation or the pine dominated interstadial did not take place at all (Räsänen et al. 2015). The one Late Weichselian glaciation (MIS 2, 29-11 kyr ago) at the SE sector of EIS was preceded in S Finland by a nearly 90 kyr long still poorly known non-glacial period, featuring tundra with permafrost and probably birch forest. The new Middle Weichselian paleoenvironmental scenario revises the configuration and hydrology of the S part of EIS and gives new setting for the evolution of Scandinavian biota. References Powell, R. D., and Cooper, J. M., 2002, A glacial sequence stratigraphic model for temperate, glaciated continental shelves, in Dowdeswell, J. A., and Cofaig, C. Ó. eds., Glacier-Influenced Sedimentation on High-Latitude Continental Margins: The Geological Society of London, London, Geological Society London, Special Publication v. 203, p. 215-244. Räsänen, M.E., Huitti, J.V., Bhattarai, S. Harvey, J. and Huttunen, S. 2015, The SE sector of the Middle

  4. Influence of system controls on the Late Quaternary geomorphic evolution of a rapidly-infilled incised-valley system: The lower Manawatu valley, North Island New Zealand

    Science.gov (United States)

    Clement, Alastair J. H.; Fuller, Ian C.

    2018-02-01

    The Manawatu incised-valley estuary was rapidly infilled between 12,000-4700 cal. yr BP. A combination of empirical measurements of sedimentation rates, a reconstruction of relative sea-level (RSL) change, and digital elevation models of key surfaces within the Holocene sedimentary fill of the valley were integrated to produce a numerical model to investigate the influence of the system controls of sea-level change, sediment flux, and accommodation space on the rapid infilling history of the palaeo-estuary. The numerical model indicates that sediment flux into the palaeo-estuary was greatest during the Holocene marine transgression between 12,000-8000 years BP. The average rate of sediment deposition in the estuary during this period was 1.0 M m3 yr- 1. This rapid rate of sedimentation was controlled by the rate of accommodation space creation, as regulated by the rate of sea-level rise and the antecedent configuration of the valley. By the time sea levels stabilised c. 7500 cal. yr BP, the palaeo-estuary had been substantively infilled. Limited accommodation space resulted in rapid infilling of the central basin, though sediment flux into the estuary between 7100 and 4500 cal. yr BP was at a lower rate of 234,000 m3 yr- 1. The limited accommodation space also influenced hydrodynamic conditions in the estuarine central basin, driving export of fine-grained sediment from the estuary. Once the accommodation space of the estuarine basin was infilled sediment bypassed the system, with a consequent reduction in the sedimentation rate in the valley. More accurate partitioning of the sources of sediment driving the infilling is necessary to quantify sediment bypassing. Post-depositional lowering of RSL index points from the valley is driven by neotectonics and sediment compaction.

  5. A hydrogeologic map of the Death Valley region, Nevada, and California, developed using GIS techniques

    International Nuclear Information System (INIS)

    Faunt, C.C.; D'Agnese, F.A.; Turner, A.K.

    1997-01-01

    In support of Yucca Mountain site characterization studies, a hydrogeologic framework was developed, and a hydrogeologic map was constructed for the Death Valley region. The region, covering approximately 100,000 km 2 along the Nevada-California border near Las Vegas, is characterized by isolated mountain ranges juxtaposed against broad, alluvium-filled valleys. Geologic conditions are typical of the Basin and Range Province; a variety of sedimentary and igneous intrusive and extrusive rocks have been subjected to both compressional and extensional deformation. The regional ground-water flow system can best be described as a series of connected intermontane basins in which ground-water flow occurs in basin-fill deposits, carbonate rocks, clastic rocks, and volcanic rocks. Previous investigations have developed more site-specific hydrogeologic relationships; however, few have described all the lithologies within the Death Valley regional ground-water flow system. Information required to characterize the hydrogeologic units in the region was obtained from regional geologic maps and reports. Map data were digitized from regional geologic maps and combined into a composite map using a geographic information system. This map was simplified to show 10 laterally extensive hydrogeologic units with distinct hydrologic properties. The hydraulic conductivity values for the hydrogeologic units range over 15 orders of magnitude due to the variability in burial depth and degree of fracturing

  6. Linking microbial diversity and functionality of arctic glacial surface habitats.

    Science.gov (United States)

    Lutz, Stefanie; Anesio, Alexandre M; Edwards, Arwyn; Benning, Liane G

    2017-02-01

    Distinct microbial habitats on glacial surfaces are dominated by snow and ice algae, which are the critical players and the dominant primary colonisers and net producers during the melt season. Here for the first time we have evaluated the role of these algae in association with the full microbial community composition (i.e., algae, bacteria, archaea) in distinct surface habitats and on 12 glaciers and permanent snow fields in Svalbard and Arctic Sweden. We cross-correlated these data with the analyses of specific metabolites such as fatty acids and pigments, and a full suite of potential critical physico-chemical parameters including major and minor nutrients, and trace metals. It has been shown that correlations between single algal species, metabolites, and specific geochemical parameters can be used to unravel mixed metabolic signals in complex communities, further assign them to single species and infer their functionality. The data also clearly show that the production of metabolites in snow and ice algae is driven mainly by nitrogen and less so by phosphorus limitation. This is especially important for the synthesis of secondary carotenoids, which cause a darkening of glacial surfaces leading to a decrease in surface albedo and eventually higher melting rates. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  7. Irrigation channels of the Upper Rhone valley (Switzerland). Geomorphological analysis of a cultural heritage

    Science.gov (United States)

    Reynard, Emmanuel

    2016-04-01

    are accentuated by high insulation and evaporation. Finally, foehn events are quite common. In a climatic point of view, the area can be divided in three main zones: (1) Upstream of Brig, the climate is characterised by cold and wet conditions, and irrigation is not necessary; (2) between Brig and Martigny, the rain shadow effect is responsible of irrigation needs in the lower altitudes, whereas at high altitudes rainfall is sufficient for plant growing without irrigation; (3) downstream of Martigny, the climate is wetter and irrigation is not necessary. In a palaeoclimatic point of view, the Rhone River catchment was characterised by numerous glaciations during the Quaternary. Quaternary glaciers have shaped the valleys (U-shaped valleys, hanged valleys) and the postglacial hydrographical network had to adapt to the glacial valleys (presence of numerous waterfalls, hanged valleys, postglacial gorges, alluvial fans). By crossing climatic and structural contexts, three groups of geomorphological contexts of irrigation channels can be highlighted: (1) In the tributary valleys situated South of the Rhone valley (Penninic Alps) the irrigation channels are simply dug in the valley slopes; several of them are affected by landslides typical of metamorphic rocks of Penninic Alps; (2) In the short tributary valleys of the crystalline Aar Massif - in the valleys North to the city of Visp -, the geomorphological context is characterised by steep slopes both in the tributary valleys and in the south-facing slopes dominating the Rhone River valley. In this area, water channels are cut into the rocks and in some parts they are built in wood pipes hanged along the rock walls; (3) In the tributary valleys of the Helvetic domain - North of the Rhone River between Leuk and Sion - the geological context highly influences the building techniques: due to geological dipping towards Southeast, the tributary valley are dissymmetric: in the dip slopes channels are simply cut in the soil

  8. Hidden Valley Search at ATLAS

    CERN Document Server

    Verducci, M

    2011-01-01

    A number of extensions of the Standard Model result in neutral and weakly-coupled particles that decay to multi hadrons or multi leptons with macroscopic decay lengths. These particles with decay paths that can be comparable with ATLAS detector dimensions represent, from an experimental point of view, a challenge both for the trigger and for the reconstruction capabilities of the ATLAS detector. We will present a set of signature driven triggers for the ATLAS detector that target such displaced decays and evaluate their performances for some benchmark models and describe analysis strategies and limits on the production of such long-lived particles. A first estimation of the Hidden Valley trigger rates has been evaluated with 6 pb-1 of data collected at ATLAS during the data taking of 2010.

  9. Assessment of periapical health, quality of root canal filling, and ...

    African Journals Online (AJOL)

    Sixty three teeth were found to have short root canal fillings, whereas 74 teeth had adequate root canal fillings, and the remaining 10 teeth had over extended root canal filling. A significant correlation was observed between the length of root filling and apical periodontitis (P = 0,023). Inadequately dense root canal filling was ...

  10. Transient electromagnetic mapping of clay units in the San Luis Valley, Colorado

    Science.gov (United States)

    Fitterman, David V.; Grauch, V.J.S.

    2010-01-01

    Transient electromagnetic soundings were used to obtain information needed to refine hydrologic models of the San Luis Valley, Colorado. The soundings were able to map an aquitard called the blue clay that separates an unconfined surface aquifer from a deeper confined aquifer. The blue clay forms a conductor with an average resistivity of 6.9 ohm‐m. Above the conductor are found a mixture of gray clay and sand. The gray clay has an average resistivity of 21 ohm‐m, while the sand has a resistivity of greater than 100 ohm‐m. The large difference in resistivity of these units makes mapping them with a surface geophysical method relatively easy. The blue clay was deposited at the bottom of Lake Alamosa which filled most of the San Luis Valley during the Pleistocene. The geometry of the blue clay is influenced by a graben on the eastern side of the valley. The depth to the blue clay is greater over the graben. Along the eastern edge of valley the blue clay appears to be truncated by faults.

  11. Glacial wetland distribution and methane emissions estimated from PMIP2 climate simulations

    NARCIS (Netherlands)

    Weber, S.L.; Drury, A.J.; Toonen, W.H.J.; Weele, M. van

    2010-01-01

    The interglacial–glacial decrease in atmospheric methane concentration is often attributed to a strong decline in the wetland source. This seems consistent with the extreme coldness and vastly expanded ice sheets. Here we analyse coupled model simulations for the last glacial maximum from the

  12. Last Glacial Maximum CO2 and d13C successfully reconciled

    NARCIS (Netherlands)

    Bouttes, N.; Paillard, D.; Roche, D.M.V.A.P.; Brovkin, V.; Bopp, L.

    2011-01-01

    During the Last Glacial Maximum (LGM, ∼21,000 years ago) the cold climate was strongly tied to low atmospheric CO2 concentration (∼190 ppm). Although it is generally assumed that this low CO2 was due to an expansion of the oceanic carbon reservoir, simulating the glacial level

  13. Weak oceanic heat transport as a cause of the instability of glacial climates

    NARCIS (Netherlands)

    Colin de Verdière, A.; Raa, L. te

    2010-01-01

    The stability of the thermohaline circulation of modern and glacial climates is compared with the help of a two dimensional ocean-atmosphere-sea ice coupled model. It turns out to be more unstable as less freshwater forcing is required to induce a polar halocline catastrophy in glacial climates. The

  14. Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment

    Science.gov (United States)

    McKnight, Diane M.; Tate, C.M.; Andrews, E.D.; Niyogi, D.K.; Cozzetto, K.; Welch, K.; Lyons, W.B.; Capone, D.G.

    2007-01-01

    The McMurdo Dry Valleys of Antarctica contain many glacial meltwater streams that flow for 6 to 12??weeks during the austral summer and link the glaciers to the lakes on the valley floors. Dry valley streams gain solutes longitudinally through weathering reactions and microbial processes occurring in the hyporheic zone. Some streams have thriving cyanobacterial mats. In streams with regular summer flow, the mats are freeze-dried through the winter and begin photosynthesizing with the onset of flow. To evaluate the longer term persistence of cyanobacterial mats, we diverted flow to an abandoned channel, which had not received substantial flow for approximately two decades. Monitoring of specific conductance showed that for the first 3??years after the diversion, the solute concentrations were greater in the reactivated channel than in most other dry valley streams. We observed that cyanobacterial mats became abundant in the reactivated channel within a week, indicating that the mats had been preserved in a cryptobiotic state in the channel. Over the next several years, these mats had high rates of productivity and nitrogen fixation compared to mats from other streams. Experiments in which mats from the reactivated channel and another stream were incubated in water from both of the streams indicated that the greater solute concentrations in the reactivated channel stimulated net primary productivity of mats from both streams. These stream-scale experimental results indicate that the cryptobiotic preservation of cyanobacterial mats in abandoned channels in the dry valleys allows for rapid response of these stream ecosystems to climatic and geomorphological change, similar to other arid zone stream ecosystems. ?? 2006 Elsevier B.V. All rights reserved.

  15. Topological materials discovery using electron filling constraints

    Science.gov (United States)

    Chen, Ru; Po, Hoi Chun; Neaton, Jeffrey B.; Vishwanath, Ashvin

    2018-01-01

    Nodal semimetals are classes of topological materials that have nodal-point or nodal-line Fermi surfaces, which give them novel transport and topological properties. Despite being highly sought after, there are currently very few experimental realizations, and identifying new materials candidates has mainly relied on exhaustive database searches. Here we show how recent studies on the interplay between electron filling and nonsymmorphic space-group symmetries can guide the search for filling-enforced nodal semimetals. We recast the previously derived constraints on the allowed band-insulator fillings in any space group into a new form, which enables effective screening of materials candidates based solely on their space group, electron count in the formula unit, and multiplicity of the formula unit. This criterion greatly reduces the computation load for discovering topological materials in a database of previously synthesized compounds. As a demonstration, we focus on a few selected nonsymmorphic space groups which are predicted to host filling-enforced Dirac semimetals. Of the more than 30,000 entires listed, our filling criterion alone eliminates 96% of the entries before they are passed on for further analysis. We discover a handful of candidates from this guided search; among them, the monoclinic crystal Ca2Pt2Ga is particularly promising.

  16. NSLS-II filling pattern measurement

    International Nuclear Information System (INIS)

    Yong Hu; Dalesio, L.B.; Kiman Ha; Pinayev, I.

    2012-01-01

    Multi-bunch injection will be deployed at NSLS-II. High bandwidth diagnostic beam monitors with high speed digitizers are used to measure bunch-by-bunch charge variation. In order to minimize intensity-correlated orbit oscillations due to uneven bunch patterns, we need to measure the filling pattern (also named bunch pattern or bunch structure). This paper focuses on filling pattern measurements: how to measure bunch structure and make this information available in EPICS-based control system. This measurement requires combination of 3 types of beam monitors (Wall Current Monitor, Fast Current Transformer and Beam Position Monitor), data acquisition and controls (fast digitizer, EPICS software, etc.) and Event Timing system. High-bandwidth filling pattern monitor requires high-speed digitizer to sample its analog output signal. The evaluation results of commercial fast digitizer Agilent Acqiris and high bandwidth detector Bergoz FCT are presented. We have also tested the algorithm software for filling pattern measurement as well as the interface to event timing system. It appears that filling pattern measurement system is well understood and the tests for control hardware and software have given good results

  17. Improving the support characteristics of hydraulic fill

    Energy Technology Data Exchange (ETDEWEB)

    Corson, D. R.; Dorman, K. R.; Sprute, R. H.

    1980-05-15

    Extensive laboratory and field testing has defined the physical properties of hydraulic fill. Effect of void ratio on percolation rate has been quantified, and tests were developed to estimate waterflow through fill material in a given state underground. Beneficial effect on fill's support capability through addition of cement alone or in conjunction with vibratory compaction has been investigated. Two separate field studies in operating cut-and-fill mines measured vein-wall deformation and loads imposed on backfilled stopes. Technology has been developed that will effectively and efficiently dewater and densify ultra-fine-grained slurries typical of metal mine hydraulic backfill. At least two operators are using this electrokinetic technique to dewater slimes collected in underground sumps or impoundments. This technique opens up the possibility of using the total unclassified tailings product as a hydraulic backfill. Theoretical enhancement of ground support and rock-burst control through improved support capability will be tested in a full-scale mine stope installation. Both a horizontal layer and a vertical column of high modulus fill will be placed in an attempt to reduce stope wall closure, support more ground pressure, and lessen rock-burst occurrence.

  18. Thermal study on the impurity effect on thermodynamic stability of the glacial phase in triphenyl phosphite-triphenyl phosphate system

    International Nuclear Information System (INIS)

    Tanabe, Ikue; Takeda, Kiyoshi; Murata, Katsuo

    2005-01-01

    To investigate the impurity effect on thermodynamic stability of the glacial phase, an apparently amorphous metastable phase observed in triphenyl phosphite (TPP), the differential scanning calorimetry (DSC) was carried out in the temperature range 120-350 K for binary mixtures between TPP and triphenyl phosphate (TPPO). Heating up from the glassy liquid, supercooled liquid phase transformed into glacial phase below the crystallization temperature for all the samples with x < 0.2, where x denotes the mole fraction of TPPO. Both transformation temperatures from liquid to glacial and from glacial to crystal increased and temperature range that glacial phase appears narrowed with the content of TPPO. The peak intensity of exothermic effect due to the transformation from liquid to glacial becomes larger whereas that from glacial to crystal reduced. The kinetic and thermodynamic stabilities were discussed for liquid and glacial phases based on the DSC results

  19. Thermal study on the impurity effect on thermodynamic stability of the glacial phase in triphenyl phosphite-triphenyl phosphate system

    Energy Technology Data Exchange (ETDEWEB)

    Tanabe, Ikue [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan); Takeda, Kiyoshi [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan)]. E-mail: takeda@naruto-u.ac.jp; Murata, Katsuo [Department of Chemistry, Naruto University of Education, Naruto, Tokushima 772-8502 (Japan)

    2005-06-15

    To investigate the impurity effect on thermodynamic stability of the glacial phase, an apparently amorphous metastable phase observed in triphenyl phosphite (TPP), the differential scanning calorimetry (DSC) was carried out in the temperature range 120-350 K for binary mixtures between TPP and triphenyl phosphate (TPPO). Heating up from the glassy liquid, supercooled liquid phase transformed into glacial phase below the crystallization temperature for all the samples with x < 0.2, where x denotes the mole fraction of TPPO. Both transformation temperatures from liquid to glacial and from glacial to crystal increased and temperature range that glacial phase appears narrowed with the content of TPPO. The peak intensity of exothermic effect due to the transformation from liquid to glacial becomes larger whereas that from glacial to crystal reduced. The kinetic and thermodynamic stabilities were discussed for liquid and glacial phases based on the DSC results.

  20. Quaternary sedimentation of the Alaskan Beaufort shelf: Influence of regional tectonics, fluctuating sea levels, and glacial sediment sources

    Science.gov (United States)

    Dinter, D.A.

    1985-01-01

    The offshore stratigraphy of the Quaternary Gubik Formation of Arctic Alaska has been studied on high-resolution seismic profiles with a maximum sub-seafloor penetration of about 100 m. In general, marine transgressive subunits of the Gubik Formation are wedge-shaped on the shelf, thickening slightly seaward to the shelf break, beyond which they are offset by landslides and slumps. Beneath the eastern third of the Alaskan Beaufort shelf, active folding has created two persistent structural depressions, the Eastern and Western Wedge Terranes, in which the wedge morphology is especially well developed. The youngest transgressive marine wedge, which was deposited in such a way as to fill these depressions, leaving a generally flat present-day shelf surface, is inferred to be late Wisconsin or younger in age because it overlies a prominent disconformity interpreted to have been formed during the late Wisconsin glacial sea-level minimum. The thickness of this youngest wedge, Unit A, locally exceeds 40 m on the outer shelf, yet apparently relict gravel deposits collected from its seabed surface indicate that the depositional rate is presently quite low on the middle and outer shelf. Lithologies of the gravels are exotic to Alaska, but similar to suites exposed in the Canadian Arctic Islands. These observations suggest a depositional scenario in which the retreating Laurentide Ice Sheet shed sediment-laden icebergs from the Canadian Arctic Islands into the Arctic Ocean following the late Wisconsin glacial maximum. These bergs were then rafted westward by the Beaufort Gyre and grounded on the Alaskan shelf by northeasterly prevailing winds. Especially large numbers of bergs accumulated in the wedge terrane embayments-created as sea level rose-and melted there, filling the embayments with their sedimentary cargo. As glacial retreat slowed, depositional rates on the shelf dwindled. This mode of deposition in the Alaskan Beaufort wedge terranes may be typical of early post-glacial

  1. Kisameet Glacial Clay: an Unexpected Source of Bacterial Diversity.

    Science.gov (United States)

    Svensson, Sarah L; Behroozian, Shekooh; Xu, Wanjing; Surette, Michael G; Li, Loretta; Davies, Julian

    2017-05-23

    Widespread antibiotic resistance among bacterial pathogens is providing the impetus to explore novel sources of antimicrobial agents. Recently, the potent antibacterial activity of certain clay minerals has stimulated scientific interest in these materials. One such example is Kisameet glacial clay (KC), an antibacterial clay from a deposit on the central coast of British Columbia, Canada. However, our understanding of the active principles of these complex natural substances is incomplete. Like soils, clays may possess complex mixtures of bacterial taxa, including the Actinobacteria , a clade known to be rich in antibiotic-producing organisms. Here, we present the first characterization of both the microbial and geochemical characteristics of a glacial clay deposit. KC harbors surprising bacterial species richness, with at least three distinct community types. We show that the deposit has clines of inorganic elements that can be leached by pH, which may be drivers of community structure. We also note the prevalence of Gallionellaceae in samples recovered near the surface, as well as taxa that include medically or economically important bacteria such as Actinomycetes and Paenibacillus These results provide insight into the microbial taxa that may be the source of KC antibacterial activity and suggest that natural clays may be rich sources of microbial and molecular diversity. IMPORTANCE Identifying and characterizing the resident microbial populations (bacteria, viruses, protozoa, and fungi) is key to understanding the ecology, chemistry, and homeostasis of virtually all sites on Earth. The Kisameet Bay deposit in British Columbia, Canada, holds a novel glacial clay with a history of medicinal use by local indigenous people. We previously showed that it has potent activity against a variety of antibiotic-resistant bacteria, suggesting it could complement our dwindling arsenal of antibiotics. Here, we have characterized the microbiome of this deposit to gain insight

  2. Evolution of high-Arctic glacial landforms during deglaciation

    Science.gov (United States)

    Midgley, N. G.; Tonkin, T. N.; Graham, D. J.; Cook, S. J.

    2018-06-01

    Glacial landsystems in the high-Arctic have been reported to undergo geomorphological transformation during deglaciation. This research evaluates moraine evolution over a decadal timescale at Midtre Lovénbreen, Svalbard. This work is of interest because glacial landforms developed in Svalbard have been used as an analogue for landforms developed during Pleistocene mid-latitude glaciation. Ground penetrating radar was used to investigate the subsurface characteristics of moraines. To determine surface change, a LiDAR topographic data set (obtained 2003) and a UAV-derived (obtained 2014) digital surface model processed using structure-from-motion (SfM) are also compared. Evaluation of these data sets together enables subsurface character and landform response to climatic amelioration to be linked. Ground penetrating radar evidence shows that the moraine substrate at Midtre Lovénbreen includes ice-rich (radar velocities of 0.17 m ns-1) and debris-rich (radar velocities of 0.1-0.13 m ns-1) zones. The ice-rich zones are demonstrated to exhibit relatively high rates of surface change (mean thresholded rate of -4.39 m over the 11-year observation period). However, the debris-rich zones show a relatively low rate of surface change (mean thresholded rate of -0.98 m over the 11-year observation period), and the morphology of the debris-rich landforms appear stable over the observation period. A complex response of proglacial landforms to climatic warming is shown to occur within and between glacier forelands as indicated by spatially variable surface lowering rates. Landform response is controlled by the ice-debris balance of the moraine substrate, along with the topographic context (such as the influence of meltwater). Site-specific characteristics such as surface debris thickness and glaciofluvial drainage are, therefore, argued to be a highly important control on surface evolution in ice-cored terrain, resulting in a diverse response of high-Arctic glacial landsystems

  3. Southern westerly winds: a pacemaker of Holocene glacial fluctuations in Patagonia?

    Science.gov (United States)

    Sagredo, E. A.; Reynhout, S.; Kaplan, M. R.; Patricio, M. I.; Aravena, J. C.; Martini, M. A.; Schaefer, J. M.

    2017-12-01

    A well-resolved glacial chronology is crucial to compare sequences of glacial/climate events within and between regions, and thus, to unravel mechanisms underlying past climate changes. Important efforts have been made towards understanding the Holocene climate evolution of the Southern Andes; however, the timing, patterns and causes of glacial fluctuations during this period still remain elusive. Recent advances in terrestrial cosmogenic nuclide surface exposure dating, together with the establishment of a Patagonian 10Be production rate, have opened new possibilities for establishing high-resolution glacial chronologies at centennial/decadal scale. Here we present a 10Be surface exposure chronology of fluctuations of a small, climate-sensitive mountain glacier at Mt. Fitz Roy area (49.3°S), spanning from the last glacial termination to the present. Thirty new 10Be ages show glacial advances and moraine building events at 17.1±0.9 ka, 13.5±0.5 ka, 10.2±0.7 ka or 9.9±0.5 ka, 6.9±0.2 ka, 6.1±0.3 ka, 4.5±0.2 ka and 0.5±0.1 ka. Similar to the pattern observed in New Zealand, this sequence features progressively less extensive glacial advances during the late-glacial and early Holocene, followed by advances of roughly similar extent during the mid- to late-Holocene. We suggest that while the magnitude of Holocene glacial fluctuations in Patagonia is modulated by SH summer insolation ("modulator"), the specific timing of these glacial events is influenced by centennial-scale shifts of the Southern Westerly Winds ("pacemaker").

  4. Fissure fillings from Finnsjoen and Studsvik Sweden

    International Nuclear Information System (INIS)

    Tullborg, E.-L.; Larsson, S.Aa.

    1982-12-01

    Samples were taken from cores and collected at different levels. The bedrock at Finnsjoen is a Svecokarelian granite-granodiorite, the most frequent mineral in the fissures being calcite. The water from boreholes have a mean S 18 O value of -12 per thousand and saturated by calcite. Isotopically three different groups of calcite have been distinguished. Ages of 29+-13x10 3 years to 79+-25x10 3 years were estimated. Two generations of quartz were recognized the minerals prehnite and lanmontite were found Most fissure filling materials have cation exchange capacities. The bedrock at Studsvik is a Svecokarelian gneiss of sedimentary type which is migmatized with calcite and chlorite as fissure filling minerals. Most fissure fillings are thin and simple Claby minerals of smectite type are also frequent. (G.B.)

  5. One-dimensional Gromov minimal filling problem

    International Nuclear Information System (INIS)

    Ivanov, Alexandr O; Tuzhilin, Alexey A

    2012-01-01

    The paper is devoted to a new branch in the theory of one-dimensional variational problems with branching extremals, the investigation of one-dimensional minimal fillings introduced by the authors. On the one hand, this problem is a one-dimensional version of a generalization of Gromov's minimal fillings problem to the case of stratified manifolds. On the other hand, this problem is interesting in itself and also can be considered as a generalization of another classical problem, the Steiner problem on the construction of a shortest network connecting a given set of terminals. Besides the statement of the problem, we discuss several properties of the minimal fillings and state several conjectures. Bibliography: 38 titles.

  6. Repeated catastrophic valley infill following medieval earthquakes in the Nepal Himalaya.

    Science.gov (United States)

    Schwanghart, Wolfgang; Bernhardt, Anne; Stolle, Amelie; Hoelzmann, Philipp; Adhikari, Basanta R; Andermann, Christoff; Tofelde, Stefanie; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

    2016-01-08

    Geomorphic footprints of past large Himalayan earthquakes are elusive, although they are urgently needed for gauging and predicting recovery times of seismically perturbed mountain landscapes. We present evidence of catastrophic valley infill following at least three medieval earthquakes in the Nepal Himalaya. Radiocarbon dates from peat beds, plant macrofossils, and humic silts in fine-grained tributary sediments near Pokhara, Nepal's second-largest city, match the timing of nearby M > 8 earthquakes in ~1100, 1255, and 1344 C.E. The upstream dip of tributary valley fills and x-ray fluorescence spectrometry of their provenance rule out local sources. Instead, geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation and debris flows that had plugged several tributaries with tens of meters of calcareous sediment from a Higher Himalayan source >60 kilometers away. Copyright © 2016, American Association for the Advancement of Science.

  7. Repeated catastrophic valley infill following medieval earthquakes in the Nepal Himalaya

    Science.gov (United States)

    Schwanghart, Wolfgang; Bernhardt, Anne; Stolle, Amelie; Hoelzmann, Philipp; Adhikari, Basanta R.; Andermann, Christoff; Tofelde, Stefanie; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

    2016-01-01

    Geomorphic footprints of past large Himalayan earthquakes are elusive, although they are urgently needed for gauging and predicting recovery times of seismically perturbed mountain landscapes. We present evidence of catastrophic valley infill following at least three medieval earthquakes in the Nepal Himalaya. Radiocarbon dates from peat beds, plant macrofossils, and humic silts in fine-grained tributary sediments near Pokhara, Nepal’s second-largest city, match the timing of nearby M > 8 earthquakes in ~1100, 1255, and 1344 C.E. The upstream dip of tributary valley fills and x-ray fluorescence spectrometry of their provenance rule out local sources. Instead, geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation and debris flows that had plugged several tributaries with tens of meters of calcareous sediment from a Higher Himalayan source >60 kilometers away.

  8. Hydro-mechanical aspects: glacial loading/erosion - the opalinus clay study

    International Nuclear Information System (INIS)

    Marschall, P.; Kupfer, T.; Kuhlmann, U.

    2004-01-01

    In Nagra's high level waste programme the future geological evolution of the investigation area in the Zurcher Weinland (NE Switzerland) is considered over a time period of around 1 Ma. Uplift, erosion and climatic changes were identified as processes that may affect the long-term performance of a repository for spent fuel (SF), vitrified high-level waste (HLW) and long-lived intermediate-level waste (ILW). The possible impact of those long-term processes on the barrier function of the host rock formation (Opalinus Clay) comprises: (i) the change of the vertical hydraulic gradient caused by changing recharge/discharge conditions in the regional aquifer systems; (ii) permeability enhancement of the host rock formation due to the uplift process; and (iii) expulsion of contaminated pore water from the disposal area as a result of repeated glacial loading. Due to the fact that the discharge level of the regional aquifer systems is defined by the Rhine valley and the regional recharge areas are characterised by moderate elevations (typically 2 are not expected within the next several million years. Hence, the topography of NE Switzerland together with the favourable hydraulic properties of the host rock formation prevent efficiently the vertical exchange of groundwater between the regional aquifer systems. Even on geological time scales of millions of years the expected vertical pore water flow through the host rock formation is in the order of 10 -14 m/s and lower. At present, the Opalinus Clay forms a perfect hydraulic barrier. The process of ongoing uplift, however, may give rise to embrittlement of the rock, entailed by permeability enhancement. Evidence for permeability enhancement of Opalinus Clay in shallow depth was observed by Hekel (1994). On the other hand, regional studies confirmed the low permeability of the Opalinus Clay formation in greater depth even when fractured (Gautschi, 2001; Marschall et al., 2003). Such evidence, together with conceptual

  9. Seismic response of the geologic structure underlying the Roman Colosseum and a 2-D resonance of a sediment valley

    OpenAIRE

    Mozco, P.; Rovelli, A.; Labak, P.; Malagnini, L.

    1995-01-01

    The seismic response of the geologic structure beneath the Colosseum is investigated using a two-dimensional modeling for a vertically incident plane SH wave. Computations indicate that the southern part of the Colosseum may be exposed to a seismic ground motion with significantly larger amplitudes, differential motion and longer duration than the northern part. because the southern part of the Colosseum is underlain by a sedimentfilled valley created by sedimentary filling of the former trib...

  10. Valley-filtered edge states and quantum valley Hall effect in gated bilayer graphene.

    Science.gov (United States)

    Zhang, Xu-Long; Xu, Lei; Zhang, Jun

    2017-05-10

    Electron edge states in gated bilayer graphene in the quantum valley Hall (QVH) effect regime can carry both charge and valley currents. We show that an interlayer potential splits the zero-energy level and opens a bulk gap, yielding counter-propagating edge modes with different valleys. A rich variety of valley current states can be obtained by tuning the applied boundary potential and lead to the QVH effect, as well as to the unbalanced QVH effect. A method to individually manipulate the edge states by the boundary potentials is proposed.

  11. Posterior bulk-filled resin composite restorations.

    DEFF Research Database (Denmark)

    van Dijken, Jan WV; Pallesen, Ulla

    2016-01-01

    up to 4mm as needed to fill the cavity 2mm short of the occlusal cavosurface. The occlusal part was completed with the nano-hybrid resin composite (Ceram X mono+). In the other cavity, the resin composite-only (Ceram X mono+) was placed in 2mm increments. The restorations were evaluated using...... Class II, 4 SDR-CeramX mono+ and 6 CeramXmono+-only restorations. The main reasons for failurewere tooth fracture (6) and secondary caries (4). The annual failure rate (AFR) for all restorations (Class I and II) was for the bulk-filled-1.1% and for the resin composite-only restorations 1...

  12. Alkaline earth filled nickel skutterudite antimonide thermoelectrics

    Science.gov (United States)

    Singh, David Joseph

    2013-07-16

    A thermoelectric material including a body centered cubic filled skutterudite having the formula A.sub.xFe.sub.yNi.sub.zSb.sub.12, where A is an alkaline earth element, x is no more than approximately 1.0, and the sum of y and z is approximately equal to 4.0. The alkaline earth element includes guest atoms selected from the group consisting of Be, Mb, Ca, Sr, Ba, Ra and combinations thereof. The filled skutterudite is shown to have properties suitable for a wide variety of thermoelectric applications.

  13. Creep of granulated loose-fill insulation

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    This report presents a proposal for a standardised method for creep tests and the necessary theoretical framework that can be used to describe creep of a granulated loose-fill material. Furthermore results from a round robin test are shown. The round robin test was carried out in collaboration...... with SP-Building Physics in Sweden and VTT Building Technology in Finland. For the round robin test a cellulosic fibre insulation material was used. The proposed standardised method for creep tests and theories are limited to cases when the granulated loose-fill material is exposed to a constant...

  14. Vegetation - San Felipe Valley [ds172

    Data.gov (United States)

    California Natural Resource Agency — This Vegetation Map of the San Felipe Valley Wildlife Area in San Diego County, California is based on vegetation samples collected in the field in 2002 and 2005 and...

  15. Babesiosis in Lower Hudson Valley, New York

    Centers for Disease Control (CDC) Podcasts

    This podcast discusses a study about an increase in babesiosis in the Lower Hudson Valley of New York state. Dr. Julie Joseph, Assistant Professor of Medicine at New York Medical College, shares details of this study.

  16. Meie mees Silicon Valleys / Kertu Ruus

    Index Scriptorium Estoniae

    Ruus, Kertu, 1977-

    2007-01-01

    Ilmunud ka: Delovõje Vedomosti 5. dets. lk. 4. Peaminister Andrus Ansip avas Eesti Ettevõtluse Sihtasutuse esinduse Silicon Valley pealinnas San Joses. Vt. samas: Ränioru kliima on tehnoloogiasõbralik; Andrus Viirg

  17. Meie ingel Silicon Valleys / Raigo Neudorf

    Index Scriptorium Estoniae

    Neudorf, Raigo

    2008-01-01

    Ettevõtluse Arendamise Sihtasutuse esinduse töölepanekust USAs Silicon Valleys räägib esinduse juht Andrus Viirg. Vt. ka: Eestlasi leidub San Franciscos omajagu; Muljetavaldav karjäär; USAga ammune tuttav

  18. Burrowing Owl - Palo Verde Valley [ds197

    Data.gov (United States)

    California Natural Resource Agency — These burrowing owl observations were collected during the spring and early summer of 1976 in the Palo Verde Valley, eastern Riverside County, California. This is an...

  19. Wetland methane emissions during the Last Glacial Maximum estimated from PMIP2 simulations: climate, vegetation and geographic controls

    NARCIS (Netherlands)

    Weber, S.L.; Drury, A.J.; Toonen, W.H.J.; Weele, M. van

    2010-01-01

    It is an open question to what extent wetlands contributed to the interglacial‐glacial decrease in atmospheric methane concentration. Here we estimate methane emissions from glacial wetlands, using newly available PMIP2 simulations of the Last Glacial Maximum (LGM) climate from coupled

  20. Inverse vertical migration and feeding in glacier lanternfish (Benthosema glaciale)

    KAUST Repository

    Dypvik, Eivind

    2011-11-08

    A bottom-mounted upward-facing 38-kHz echo sounder was deployed at ~400 m and cabled to shore in Masfjorden (~60 52?N, ~5 24?E), Norway. The scattering layers seen during autumn (September-October) 2008 were identified by trawling. Glacier lanternfish (Benthosema glaciale) were mainly distributed below ~200 m and displayed three different diel behavioral strategies: normal diel vertical migration (NDVM), inverse DVM (IDVM) and no DVM (NoDVM). The IDVM group was the focus of this study. It consisted of 2-year and older individuals migrating to ~200-270 m during the daytime, while descending back to deeper than ~270 m during the night. Stomach content analysis revealed increased feeding during the daytime on overwintering Calanus sp. We conclude that visually searching glacier lanternfish performing IDVM benefit from the faint daytime light in mid-waters when preying on overwintering Calanus sp. 2011 The Author(s).

  1. A simple conceptual model of abrupt glacial climate events

    Directory of Open Access Journals (Sweden)

    H. Braun

    2007-11-01

    Full Text Available Here we use a very simple conceptual model in an attempt to reduce essential parts of the complex nonlinearity of abrupt glacial climate changes (the so-called Dansgaard-Oeschger events to a few simple principles, namely (i the existence of two different climate states, (ii a threshold process and (iii an overshooting in the stability of the system at the start and the end of the events, which is followed by a millennial-scale relaxation. By comparison with a so-called Earth system model of intermediate complexity (CLIMBER-2, in which the events represent oscillations between two climate states corresponding to two fundamentally different modes of deep-water formation in the North Atlantic, we demonstrate that the conceptual model captures fundamental aspects of the nonlinearity of the events in that model. We use the conceptual model in order to reproduce and reanalyse nonlinear resonance mechanisms that were already suggested in order to explain the characteristic time scale of Dansgaard-Oeschger events. In doing so we identify a new form of stochastic resonance (i.e. an overshooting stochastic resonance and provide the first explicitly reported manifestation of ghost resonance in a geosystem, i.e. of a mechanism which could be relevant for other systems with thresholds and with multiple states of operation. Our work enables us to explicitly simulate realistic probability measures of Dansgaard-Oeschger events (e.g. waiting time distributions, which are a prerequisite for statistical analyses on the regularity of the events by means of Monte-Carlo simulations. We thus think that our study is an important advance in order to develop more adequate methods to test the statistical significance and the origin of the proposed glacial 1470-year climate cycle.

  2. Cosmogenic 10Be Dating of Northern Quebec-Labrador Glacial Lake Shorelines and Drainage Deposits: Implications for the Final Meltwater Discharges of the Last Deglaciation

    Science.gov (United States)

    Roy, M.; Dube-Loubert, H.; Schaefer, J. M.; Hébert, S.

    2017-12-01

    The decay of the Laurentide ice sheet played an important role in the climate variability of the last deglaciation, notably through large discharges of meltwater from glacial lakes that disturbed the Atlantic meridional overturning oceanic circulation (AMOC). These former climate-forcing events are now under focus due to growing evidence showing that the present-day increase in freshwater releases from Greenland and other Arctic glaciers may potentially lead to a slowdown of the AMOC and cause important climate feedbacks. In northern Quebec and Labrador, the end of the deglaciation led to the formation of at least 10 important glacial lakes that drained into the nearby Labrador Sea where repeated meltwater discharges could have destabilized the ocean surface conditions in this key sector of the North Atlantic Ocean. Although the drainage of these ice-dammed lakes may form a good analogue for modern processes, the lack of direct constraints on the physiographic configuration and temporal evolution of these lakes limits our understanding of the timing and climate impact of these final meltwater pulses. Here we applied cosmogenic 10Be dating to raised boulder shorelines belonging to Lake Naskaupi, one of the largest glacial lakes in northern Quebec and Labrador. We reconstructed the lake extent and meltwater volume, as well as its lake-level history by systematic mapping of geomorphic features. We sampled a total of 16 boulders at 4 sites along the valley. In addition, we dated five boulders belonging to a large-scale outburst flood deposit recording the abrupt drainage of the lake. The distribution of the 21 ages shows a remarkable consistency, yielding a mean age of 7.8 ± 0.4 ka (1 outlier excluded). The ages from the shorelines are indistinguishable from those of the outburst flood deposit, suggesting that Lake Naskaupi existed for a relatively short time span. These new chronological data constrain the timing of the lake development and attendant drainage

  3. The structure of filled skutterudites and the local vibration behavior of the filling atom

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaojuan [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Dongguan Institute of Neutron Science, Dongguan 523808 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zong, Peng-an [State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Chen, Xihong [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Tao, Juzhou, E-mail: taoj@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Dongguan Institute of Neutron Science, Dongguan 523808 (China); Lin, He, E-mail: linhe@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Science, Shanghai 201204 (China)

    2017-02-15

    Both of atomic pair distribution function (PDF) and extended x-ray absorption fine structure (EXAFS) experiments have been carried out on unfilled and Yb-filled skutterudites Yb{sub x}Co{sub 4}Sb{sub 12} (x=0, 0.15, 0.2 and 0.25) samples. The structure refinements on PDF data confirm the large amplitude vibration of Yb atom and the dependence of Yb vibration amplitude on the filling content. Temperature dependent EXAFS experiment on filled skutterudites have been carried out at Yb L{sub Ⅲ}-edge in order to explore the local vibration behavior of filled atom. EXAFS experiments show that the Einstein temperature of the filled atom is very low (70.9 K) which agrees with the rattling behavior.

  4. Stress evolution and fault stability during the Weichselian glacial cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lund, Bjoern; Schmidt, Peter; Hieronymus, Christoph (Dept. of Earth Sciences, Uppsala Univ., Uppsala (Sweden))

    2009-10-15

    In this report we examine how the waxing and waning of an ice sheet during a glacial cycle affects the state of stress in the Earth, and how those changes in stress influence the stability of faults. We focus on the stresses at repository depth in Forsmark and Oskarshamn, and on the stability field at seismogenic depth at the proposed repository sites and at the Paervie endglacial fault in northern Sweden. This study is a modelling study, where we use 3-dimensional ice and earth models to calculate the glacial isostatic adjustment (GIA), i.e. the response of the Earth to an ice load, examining both displacements and stresses. We use a flat-earth finite element approach, based on Wu with some modifications. The result presented here is a continuation of previous studies in 2 dimensions and complement those studies in assessing how the 3-dimensionality of the problem affects the conclusions. We use the Fennoscandian ice model of Naeslund, which is a dynamic ice sheet model based on climate reconstructions with constraints from geological observations. The ice model spans the entire Weichselian glaciation but we only use the last 68 kyr, which includes the 2 major periods of ice cover as depicted in this ice sheet reconstruction. For the GIA calculation we use a number of different earth models, both with flat horizontal layers and with various 3D structures of lithosphere thickness. We don't include lateral variations in the viscosity of the mantle. Comparing the current day rebound velocities predicted by our models with GPS observations from the BIFROST project, we note that in general, we can obtain a reasonable fit to the observations with our models, and that the results are rather sensitive to the assumed viscosity of the mantle. We find that the differences between data and model results, for all earth models, have common features which we interpret as due to the ice model. These observations are in agreement with numerous other GIA studies. Our flat

  5. Stress evolution and fault stability during the Weichselian glacial cycle

    International Nuclear Information System (INIS)

    Lund, Bjoern; Schmidt, Peter; Hieronymus, Christoph

    2009-01-01

    In this report we examine how the waxing and waning of an ice sheet during a glacial cycle affects the state of stress in the Earth, and how those changes in stress influence the stability of faults. We focus on the stresses at repository depth in Forsmark and Oskarshamn, and on the stability field at seismogenic depth at the proposed repository sites and at the Paervie endglacial fault in northern Sweden. This study is a modelling study, where we use three-dimensional ice and earth models to calculate the glacial isostatic adjustment (GIA), i.e. the response of the Earth to an ice load, examining both displacements and stresses. We use a flat-earth finite element approach, based on Wu with some modifications. The result presented here is a continuation of previous studies in two dimensions and complement those studies in assessing how the three-dimensionality of the problem affects the conclusions. We use the Fennoscandian ice model of Naeslund, which is a dynamic ice sheet model based on climate reconstructions with constraints from geological observations. The ice model spans the entire Weichselian glaciation but we only use the last 68 kyr, which includes the two major periods of ice cover as depicted in this ice sheet reconstruction. For the GIA calculation we use a number of different earth models, both with flat horizontal layers and with various 3D structures of lithosphere thickness. We do not include lateral variations in the viscosity of the mantle. Comparing the current day rebound velocities predicted by our models with GPS observations from the BIFROST project, we note that in general, we can obtain a reasonable fit to the observations with our models, and that the results are rather sensitive to the assumed viscosity of the mantle. We also find that the differences between data and model results, for all earth models, have common features which we interpret as due to the ice model. These observations are in agreement with numerous other GIA studies

  6. Electrical valley filtering in transition metal dichalcogenides

    Science.gov (United States)

    Hsieh, Tzu-Chi; Chou, Mei-Yin; Wu, Yu-Shu

    2018-03-01

    This work investigates the feasibility of electrical valley filtering for holes in transition metal dichalcogenides. We look specifically into the scheme that utilizes a potential barrier to produce valley-dependent tunneling rates, and perform the study with both a k .p -based analytic method and a recursive Green's function-based numerical method. The study yields the transmission coefficient as a function of incident energy and transverse wave vector, for holes going through lateral quantum barriers oriented in either armchair or zigzag directions, in both homogeneous and heterogeneous systems. The main findings are the following: (1) The tunneling current valley polarization increases with increasing barrier width or height; (2) both the valley-orbit interaction and band structure warping contribute to valley-dependent tunneling, with the former contribution being manifest in structures with asymmetric potential barriers, and the latter being orientation dependent and reaching maximum for transmission in the armchair direction; and (3) for transmission ˜0.1 , a tunneling current valley polarization of the order of 10 % can be achieved.

  7. Glacialmorphological reconstruction of glacier advances and glacial lake outburst floods at the Cachapoal glacier in the Dry Central Andes of Chile (34°S)

    Science.gov (United States)

    Iturrizaga, Lasafam; Charrier, Reynaldo

    2013-04-01

    Throughout the Andes Mountain range of South America a general trend of glacier shrinkage has taken place in the last century. Only a few glaciers have shown a rather non-continuous trend of glacier retreat and temporally advanced or even surged during the mid-19th to 20th century. One of the earliest assumed glacier surges has occurred in the upper Cachapoal catchment area at the homonymous glacier. In climatic respect the Cachapoal glacier is located in the transition zone from the most southern part of the Dry Central Andes of Chile to the more humid zone of the Wet Andes. The region is affected mainly by winter precipitation deriving from the Westerlies. The debris-covered, 12 km-long Cachapoal glacier represents one of the largest valley glaciers in the Central Andes. It is an avalanche-fed glacier with an almost 1500 m-high head wall in its upper catchment area flowing down from Picos del Barroso (5180 m) and terminates at an elevation of 2630 m a.s.l. with a bifurcated glacier tongue. A large moraine complex, almost 2 km in length and 500 m in width, separates the two glacier lobes. During times of advanced glacier tongue positions the Ríos Molina and Cachapoal may be have blocked independently at two distinct localities which are situated about 2300 m apart from each other. A blockage with temporal lake formation has occurred at least in the years 1848, 1955 and 1981 (cf. Plagemann 1887, Peña 1981), from which the rupture of the earliest glacier barrier has been the most devastating. This event is locally reminded as "la gran avenida en seco" in the historical record. Geomorphological evidence of the past historical and modern glacier expansions is given in the proglacial area by a fresh dead-ice hummocky topography and glacial trimlines at the valley flanks. More down valley broad outwash plains and boulder clusters indicate past high energy floods produced by glacier lake outbursts. Regarding the small size of the catchment area of the Río Molina

  8. Observing Seasonal and Diurnal Hydrometeorological Variability Within a Tropical Alpine Valley: Implications for Evapotranspiration

    Science.gov (United States)

    Hellstrom, R. A.; Mark, B. G.

    2007-12-01

    Conditions of glacier recession in the seasonally dry tropical Peruvian Andes motivate research to better constrain the hydrological balance in alpine valleys. There is an outstanding need to better understand the impact of the pronounced tropical hygric seasonality on energy and water budgets within pro-glacial valleys that channel glacier runoff to stream flow. This paper presents a novel embedded network installed in the glacierized Llanganuco valley of the Cordillera Blanca (9°S) comprising eight low-cost, discrete temperature and humidity microloggers ranging from 3470 to 4740 masl and an automatic weather station at 3850 masl. Data are aggregated into distinct dry and wet periods sampled from two full annual cycles (2004-2006) to explore patterns of diurnal and seasonal variability. The magnitude of diurnal solar radiation varies little within the valley between the dry and wet periods, while wet season near-surface air temperatures are cooler. Seasonally characteristic diurnal fluctuations in lapse rate partially regulate convection and humidity. Steep lapse rates during the wet season afternoon promote up-slope convection of warm, moist air and nocturnal rainfall events. Standardized grass reference evapotranspiration (ET0) was estimated using the FAO-56 algorithm of the United Nations Food and Agriculture Organization and compared with estimates of actual ET from the process-based BROOK90 model that incorporates more realistic vegetation parameters. Comparisons of composite diurnal cycles of ET for the wet and dry periods suggest about twice the daily ET0 during the dry period, attributed primarily to the 500% higher vapor pressure deficit and 20% higher daily total solar irradiance. Conversely, the near absence of rainfall during the dry season diminishes actual ET below that of the wet season by two orders of magnitude. Nearly cloud-free daylight conditions are critical for ET during the wet season. We found significant variability of ET with elevation

  9. Cataclysmic Rock Avalanche from El Capitan, Yosemite Valley, circa 3.6 ka

    Science.gov (United States)

    Stock, G. M.

    2008-12-01

    El Capitan in Yosemite Valley is one of the largest and most iconic granite faces in the world. Despite glacially steepened walls exceeding 90 degrees, a historic database shows relatively few rock falls from El Capitan in the past 150 years. However, a massive bouldery deposit beneath the southeast face suggests an earlier rock avalanche of unusually large size. Spatial analysis of airborne LiDAR data indicate that the rock avalanche deposit has a volume of ~2.70 x 106 m3, a maximum thickness of 18 m, and a runout distance of 660 m, roughly twice the horizontal extent of the adjacent talus. The deposit is very coarse on its distal edge, with individual boulder volumes up to 2500 m3. Cosmogenic 10Be exposure dates from boulders distributed across the deposit confirm this interpretation. Four 10Be samples are tightly clustered between 3.5 and 3.8 ka, with a mean age of 3.6 +/- 0.6 ka. A fifth sample gives a much older age of 22.0 ka, but a glacier occupied Yosemite Valley at this time, prohibiting deposition; thus, the older age likely results from exposure on the cliff face prior to failure. The similarity of ages and overall morphology suggest that the entire deposit formed during a single event. The mean exposure age coincides with inferred Holocene rupture of the northern Owens Valley and/or White Mountain fault(s) between 3.3 and 3.8 ka (Lee et al., 2001; Bacon and Pezzopane, 2007). This time coincidence, combined with the fact that historic rupture of the Owens Valley fault in A.D. 1872 generated numerous large rock falls in Yosemite Valley, strongly suggests that the El Capitan rock avalanche was triggered by a seismic event along the eastern margin of the Sierra Nevada circa 3.6 ka. As there is not an obvious "scar" on the expansive southeast face, the exact source area of the rock avalanche is not yet known. Detrital apatite U-Th/(He) thermochronometry can determine the elevation(s) from which rock fall boulders originate, but significant inter-sample age

  10. Provenance of radioactive placers, Big Meadow area, Valley and Boise Counties, Idaho

    International Nuclear Information System (INIS)

    Truesdell, D.; Wegrzyn, R.; Dixon, M.

    1977-02-01

    For many years, radioactive black-sand placers have been known to be present in the Bear Valley area of west-central Idaho. The largest of these is in Big Meadow, near the head of Bear Valley Creek. Presence of these placers suggests that low-grade uranium deposits might occur in rocks of the Idaho Batholith, adjacent to Bear Valley. This study was undertaken to locate the provenance of the radioactive minerals and to identify problems that need to be solved before undertaking further investigations. The principal radioactive minerals in these placers are monazite and euxenite. Other minerals include columbite, samarskite, fergusonite, xenotime, zircon, allanite, sphene, and brannerite. Only brannerite is a uranium mineral; the others contain uranium as an impurity in crystal lattices. Radiometric determinations of the concentration of uranium in stream sediments strongly indicate that the radioactive materials originate in an area drained by Casner and Howard Creeks. Equivalent uranium levels in bedrock are highest on the divide between Casner and Howard Creeks. However, this area is not known to contain low-grade uranium occurrences. Euxenite, brannerite, columbite-tantalite, samarskite, and allanite are the principal radioactive minerals that were identified in rock samples. These minerals were found in granite pegmatites, granites, and quartz monzonites. Appreciably higher equivalent uranium concentrations were also found within these rock types. The major problem encountered in this study was the difficulty in mapping bedrock because of extensive soil and glacial mantle. A partial solution to this problem might be the application of radon emanometry so that radiometric measurements would not be limited to the sparse bedrock samples

  11. Glacial lake monitoring in the Karakoram Range using historical Landsat Thematic Mapper archive (1982 - 2014)

    Science.gov (United States)

    Chan, J. Y. H.; Kelly, R. E. J.; Evans, S. G.

    2014-12-01

    Glacierized regions are one of the most dynamic land surface environments on the planet (Evans and Delaney, In Press). They are susceptible to various types of natural hazards such as landslides, glacier avalanches, and glacial lake outburst floods (GLOF). GLOF events are increasingly common and present catastrophic flood hazards, the causes of which are sensitive to climate change in complex high mountain topography (IPCC, 2013). Inundation and debris flows from GLOF events have repeatedly caused significant infrastructure damages and loss of human lives in the high mountain regions of the world (Huggel et al, 2002). The research is designed to develop methods for the consistent detection of glacier lakes formation during the Landsat Thematic Mapper (TM) era (1982 - present), to quantify the frequency of glacier lake development and estimate lake volume using Landsat imagery and digital elevation model (DEM) data. Landsat TM scenes are used to identify glacier lakes in the Shimshal and Shaksgam valley, particularly the development of Lake Virjeab in year 2000 and Kyagar Lake in 1998. A simple thresholding technique using Landsat TM infrared bands, along with object-based segmentation approaches are used to isolate lake extent. Lake volume is extracted by intersecting the lake extent with the DEM surface. Based on previous studies and DEM characterization in the region, Shuttle Radar Topography Mission (SRTM) DEM is preferred over Advanced Spaceborne Thermal Emission and Reflection (ASTER) GDEM due to higher accuracy. Calculated errors in SRTM height estimates are 5.81 m compared with 8.34 m for ASTER. SRTM data are preferred because the DEM measurements were made over short duration making the DEM internally consistent. Lake volume derived from the Landsat TM imagery and DEM are incorporated into a simple GLOF model identified by Clague and Matthews (1973) to estimate the potential peak discharge (Qmax) of a GLOF event. We compare the simple Qmax estimates with

  12. Form Filling with Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2002-01-01

    This paper describes a newly started Ph.D. project with the aim of simulating the form filling ability of Self-Compacting Concrete (SCC) taking into account the form geometry, reinforcement configuration, casting technique, and the rheological properties of the concrete. Comparative studies...

  13. Stock keeping unit fill rate specification

    NARCIS (Netherlands)

    Teunter, R. H.; Syntetos, A. A.; Babai, M. Z.

    2017-01-01

    The fill rate is the most widely applied service level measure in industry and yet there is minimal advice available on how it should be differentiated on an individual Stock Keeping Unit (SKU) basis given that there is an overall system target service level. The typical approach utilized in

  14. New Skeletal-Space-Filling Models

    Science.gov (United States)

    Clarke, Frank H.

    1977-01-01

    Describes plastic, skeletal molecular models that are color-coded and can illustrate both the conformation and overall shape of small molecules. They can also be converted to space-filling counterparts by the additions of color-coded polystyrene spheres. (MLH)

  15. Safety distances for hydrogen filling stations

    NARCIS (Netherlands)

    Matthijsen, A J C M; Kooi, E S

    2006-01-01

    In the context of spatial planning the Dutch Ministry of Housing, Spatial Planning and the Environment asked the Centre for External Safety of the National Institute for Public Health and the Environment (RIVM) to advice on safe distances pertaining to hydrogen filling stations. The RIVM made use of

  16. Banach spaces that realize minimal fillings

    International Nuclear Information System (INIS)

    Bednov, B. B.; Borodin, P. A.

    2014-01-01

    It is proved that a real Banach space realizes minimal fillings for all its finite subsets (a shortest network spanning a fixed finite subset always exists and has the minimum possible length) if and only if it is a predual of L 1 . The spaces L 1 are characterized in terms of Steiner points (medians). Bibliography: 25 titles. (paper)

  17. INS gas-filled recoil isotope separator

    International Nuclear Information System (INIS)

    Miyatake, M.; Nomura, T.; Kawakami, H.

    1986-09-01

    The characteristics and performance of a small sized gas-filled recoil isotope separator recently made at INS are described. The total efficiency and the ΔBρ/Bρ values have been measured using low velocity 16 O, 40 Ar and 68 As ions and found to be 10 and 5 %, respectively. The Z-dependence of the mean charge is discussed. (author)

  18. Stability of fruit bases and chocolate fillings

    Directory of Open Access Journals (Sweden)

    Joice Natali Miquelim

    2011-03-01

    Full Text Available Syrups with high sugar content and dehydrated fruits in its composition can be added to chocolate fillings to reduce the need of artificial flavor and dyes attributing a natural appeal to the product. Fruit bases were produced with lyophilized strawberry, passion fruit, and sliced orange peel. Rheological dynamic oscillatory tests were applied to determine the products stability and tendency of shelf life. Values of G´ G´´ were found for orange flavor during the 90 days of storage. It was observed that shear stress values did not vary significantly suggesting product stability during the studied period. For all fillings, it was found a behavior similar to the fruit base indicating that it has great influence on the filling behavior and its stability. The use of a sugar matrix in fillings provided good shelf life for the fruit base, which could be kept under room temperature conditions for a period as long as one year. The good stability and storage conditions allow the use of fruit base for handmade products as well as for industrialized products.

  19. Full-waveform inversion: Filling the gaps

    KAUST Repository

    Beydoun, Wafik B.; Alkhalifah, Tariq Ali

    2015-01-01

    After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi

  20. Safety Distances for hydrogen filling stations

    Energy Technology Data Exchange (ETDEWEB)

    Matthijsen, A. J. C. M.; Kooi, E. S.

    2005-07-01

    In the Netherlands there is a growing interest in using natural gas as a transport fuel. The most important drivers behind this development are formed by poor inner city air quality and the decision to close several LPG filling stations. Dwellings are not allowed within the safety distances of 45 or 110 meters from the tanker filling point of these LPG stations, depending on the capacity of the station. Another driver is global warming. We are carrying out a study on station supply, compression, storage and filling for natural gas stations, and a similar, simultaneous study on hydrogen as a followup to our risk analysis for the hydrogen filling station in Amsterdam. Here, three buses drive on hydrogen as part of the European CUTE project. Driving on natural gas is an important step in the transition to cars on hydrogen. This study was commissioned by the Dutch Ministry of Spatial Planning, Housing and the Environment to advise on external safety aspects of future hydrogen filling stations. According to Dutch law homes may not be built within an individual risk contour of 10-6 per year of a dangerous object, such as a plant with hazardous materials or a filling station. An individual risk contour of 10-6 is represented by a line around a dangerous object that connects locations with an individual risk level of 10-6 per year. An individual 'located' within this contour line has a chance of one per million per year or more to be killed as a result of an accident caused by this object. The longest distance between the object and such a contour is called a 'safety distance'. A study on safety distances is now in progress for different kinds of hydrogen filling stations (e. g. gaseous and liquid hydrogen) and for different capacities, such as big, medium and small stations. The focus is on different kinds of hydrogen production and the hydrogen supply of the filling station. To decide on the design and supply of the hydrogen station, we examined the

  1. Mountains, glaciers, and mines—The geological story of the Blue River valley, Colorado, and its surrounding mountains

    Science.gov (United States)

    Kellogg, Karl; Bryant, Bruce; Shroba, Ralph R.

    2016-02-10

    This report describes, in a nontechnical style, the geologic history and mining activity in the Blue River region of Colorado, which includes all of Summit County. The geologic story begins with the formation of ancient basement rocks, as old as about 1700 million years, and continues with the deposition of sedimentary rocks on a vast erosional surface beginning in the Cambrian Period (about 530 million years ago). This deposition was interrupted by uplift of the Ancestral Rocky Mountains during the late Paleozoic Era (about 300 million years ago). The present Rocky Mountains began to rise at the close of the Mesozoic Era (about 65 million years ago). A few tens of millions years ago, rifting began to form the Blue River valley; a major fault along the east side of the Gore Range dropped the east side down, forming the present valley. The valley once was filled by sediments and volcanic rocks that are now largely eroded. During the last few hundred-thousand years, at least two periods of glaciation sculpted the mountains bordering the valley and glaciers extended down the Blue River valley as far south as present Dillon Reservoir. Discovery of deposits of gold, silver, copper, and zinc in the late 1800s, particularly in the Breckenridge region, brought an influx of early settlers. The world-class molybdenum deposit at Climax, mined since the First World War, reopened in 2012 after a period of closure.

  2. The De Long Trough: a newly discovered glacial trough on the East Siberian continental margin

    Directory of Open Access Journals (Sweden)

    M. O'Regan

    2017-09-01

    Full Text Available Ice sheets extending over parts of the East Siberian continental shelf have been proposed for the last glacial period and during the larger Pleistocene glaciations. The sparse data available over this sector of the Arctic Ocean have left the timing, extent and even existence of these ice sheets largely unresolved. Here we present new geophysical mapping and sediment coring data from the East Siberian shelf and slope collected during the 2014 SWERUS-C3 expedition (SWERUS-C3: Swedish – Russian – US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions. The multibeam bathymetry and chirp sub-bottom profiles reveal a set of glacial landforms that include grounding zone formations along the outer continental shelf, seaward of which lies a  >  65 m thick sequence of glacio-genic debris flows. The glacial landforms are interpreted to lie at the seaward end of a glacial trough – the first to be reported on the East Siberian margin, here referred to as the De Long Trough because of its location due north of the De Long Islands. Stratigraphy and dating of sediment cores show that a drape of acoustically laminated sediments covering the glacial deposits is older than ∼ 50 cal kyr BP. This provides direct evidence for extensive glacial activity on the Siberian shelf that predates the Last Glacial Maximum and most likely occurred during the Saalian (Marine Isotope Stage (MIS 6.

  3. In and out of glacial extremes by way of dust‑climate feedbacks

    Science.gov (United States)

    Shaffer, Gary; Lambert, Fabrice

    2018-03-01

    Mineral dust aerosols cool Earth directly by scattering incoming solar radiation and indirectly by affecting clouds and biogeochemical cycles. Recent Earth history has featured quasi-100,000-y, glacial‑interglacial climate cycles with lower/higher temperatures and greenhouse gas concentrations during glacials/interglacials. Global average, glacial maxima dust levels were more than 3 times higher than during interglacials, thereby contributing to glacial cooling. However, the timing, strength, and overall role of dust‑climate feedbacks over these cycles remain unclear. Here we use dust deposition data and temperature reconstructions from ice sheet, ocean sediment, and land archives to construct dust‑climate relationships. Although absolute dust deposition rates vary greatly among these archives, they all exhibit striking, nonlinear increases toward coldest glacial conditions. From these relationships and reconstructed temperature time series, we diagnose glacial‑interglacial time series of dust radiative forcing and iron fertilization of ocean biota, and use these time series to force Earth system model simulations. The results of these simulations show that dust‑climate feedbacks, perhaps set off by orbital forcing, push the system in and out of extreme cold conditions such as glacial maxima. Without these dust effects, glacial temperature and atmospheric CO2 concentrations would have been much more stable at higher, intermediate glacial levels. The structure of residual anomalies over the glacial‑interglacial climate cycles after subtraction of dust effects provides constraints for the strength and timing of other processes governing these cycles.

  4. Root canal filling using Resilon: a review.

    LENUS (Irish Health Repository)

    Shanahan, D J

    2011-07-01

    Root canal treatment is achieved by chemo-mechanical debridement of the root canal system followed by filling. The filling material \\'entombs\\' residual bacteria and acts as a barrier which prevents the entrance of oral microorganisms and reinfection of the root canal system through microleakage. However, filling with contemporary root filling materials such as gutta-percha offers limited long-term resistance to microorganisms; as a result other materials such as Resilon have been investigated as alternatives. The aim of this review was to analyse the literature to consider whether Resilon is a suitable root canal filling material. A MEDLINE and Cochrane library search including various keyword searches identified several papers which investigated or discussed Resilon or RealSeal\\/Epiphany. Analysis of the literature demonstrated that the bulk of the literature is in vitro in nature, based largely on leakage-type studies, and demonstrates a wide variety of methodologies with conflicting findings; as a result meaningful conclusions are difficult. Within the limit of these in vitro studies Resilon appears to perform adequately in comparison to gutta-percha, however, as a result of the questionable merit of such studies, it cannot presently be considered an evidence-based alternative to the current gold standard gutta-percha. It is imperative that before Resilon is considered as a replacement material, a better understanding of the physical properties of the resin sealer and the reality of the adhesive \\'monoblock\\' are elucidated. The literature also demonstrates a paucity of quality long-term clinical outcome studies which will need to be addressed before firm conclusions can be reached.

  5. Phosphorus burial in the ocean over glacial-interglacial time scales

    Directory of Open Access Journals (Sweden)

    F. Tamburini

    2009-04-01

    Full Text Available The role of nutrients, such as phosphorus (P, and their impact on primary productivity and the fluctuations in atmospheric CO2 over glacial-interglacial periods are intensely debated. Suggestions as to the importance of P evolved from an earlier proposal that P actively participated in changing productivity rates and therefore climate change, to most recent ones that changes in the glacial ocean inventory of phosphorus were important but not influential if compared to other macronutrients, such as nitrate. Using new data coming from a selection of ODP sites, we analyzed the distribution of oceanic P sedimentary phases and calculate reactive P burial fluxes, and we show how P burial fluxes changed over the last glacial-interglacial period at these sites. Concentrations of reactive P are generally lower during glacial times, while mass accumulation rates (MAR of reactive P show higher variability. If we extrapolate for the analyzed sites, we may assume that in general glacial burial fluxes of reactive P are lower than those during interglacial periods by about 8%, because the lack of burial of reactive P on the glacial shelf reduced in size, was apparently not compensated by burial in other regions of the ocean. Using the calculated changes in P burial, we evaluate their possible impact on the phosphate inventory in the world oceans. Using a simple mathematical approach, we find that these changes alone could have increased the phosphate inventory of glacial ocean waters by 17–40% compared to interglacial stages. Variations in the distribution of sedimentary P phases at the investigated sites seem to indicate that at the onset of interglacial stages, shallower sites experienced an increase in reactive P concentrations, which seems to point to P-richer waters at glacial terminations. All these findings would support the Shelf-Nutrient Hypothesis, which assumes that during glacial low stands nutrients are transferred from shallow sites

  6. Topological Valley Transport in Two-dimensional Honeycomb Photonic Crystals.

    Science.gov (United States)

    Yang, Yuting; Jiang, Hua; Hang, Zhi Hong

    2018-01-25

    Two-dimensional photonic crystals, in analogy to AB/BA stacking bilayer graphene in electronic system, are studied. Inequivalent valleys in the momentum space for photons can be manipulated by simply engineering diameters of cylinders in a honeycomb lattice. The inequivalent valleys in photonic crystal are selectively excited by a designed optical chiral source and bulk valley polarizations are visualized. Unidirectional valley interface states are proved to exist on a domain wall connecting two photonic crystals with different valley Chern numbers. With the similar optical vortex index, interface states can couple with bulk valley polarizations and thus valley filter and valley coupler can be designed. Our simple dielectric PC scheme can help to exploit the valley degree of freedom for future optical devices.

  7. Magnetic Signature of Glacial Flour in Sediments From Bear Lake, Utah/Idaho

    Science.gov (United States)

    Rosenbaum, J. G.; Dean, W. E.; Colman, S. M.; Reynolds, R. L.

    2002-12-01

    Variations in magnetic properties within an interval of Bear Lake sediments correlative with oxygen isotope stage 2 (OIS 2) and OIS 3 provide a record of glacial flour production for the Uinta Mountains. Like sediments of the same age from Upper Klamath Lake (OR), these Bear Lake sediments have high magnetic susceptibilities (MS) relative to non-glacial-age sediments and contain well-defined millennial-scale variations in magnetic properties. In contrast to glacial flour derived from volcanic rocks surrounding Upper Klamath Lake, glacial flour derived from the Uinta Mountains and deposited in Bear Lake by the Bear River has low magnetite content but high hematite content. The relatively low MS values of younger and older non-glacial-age sediments are due entirely to dilution by non-magnetic endogenic carbonate and to the effects of sulfidic alteration of detrital Fe-oxides. Analysis of samples from streams entering Bear Lake and from along the course of the Bear River demonstrates that, in comparison to other areas of the catchment, sediment derived from the Uinta Mountains is rich in hematite (high HIRM) and aluminum, and poor in magnetite (low MS) and titanium. Within the glacial-age lake sediments, there are strong positive correlations among HIRM, Al/Ti, and fine sediment grain size. MS varies inversely with theses three variables. These relations indicate that the observed millennial-scale variations in magnetic and chemical properties arise from varying proportions of two detrital components: (1) very fine-grained glacial flour derived from Proterozoic metasedimentary rocks in the Uinta Mountains and characterized by high HIRM and low MS, and (2) somewhat coarser material, characterized by higher MS and lower HIRM, derived from widespread sedimentary rocks along the course of the Bear River and around Bear Lake. Measurement of glacial flour incorporated in lake sediments can provide a continuous history of alpine glaciation, because the rate of accumulation

  8. Climatic and geologic controls on suspended sediment flux in the Sutlej River Valley, western Himalaya

    Directory of Open Access Journals (Sweden)

    H. Wulf

    2012-07-01

    Full Text Available The sediment flux through Himalayan rivers directly impacts water quality and is important for sustaining agriculture as well as maintaining drinking-water and hydropower generation. Despite the recent increase in demand for these resources, little is known about the triggers and sources of extreme sediment flux events, which lower water quality and account for extensive hydropower reservoir filling and turbine abrasion. Here, we present a comprehensive analysis of the spatiotemporal trends in suspended sediment flux based on daily data during the past decade (2001–2009 from four sites along the Sutlej River and from four of its main tributaries. In conjunction with satellite data depicting rainfall and snow cover, air temperature and earthquake records, and field observations, we infer climatic and geologic controls of peak suspended sediment concentration (SSC events. Our study identifies three key findings: First, peak SSC events (≥ 99th SSC percentile coincide frequently (57–80% with heavy rainstorms and account for about 30% of the suspended sediment flux in the semi-arid to arid interior of the orogen. Second, we observe an increase of suspended sediment flux from the Tibetan Plateau to the Himalayan Front at mean annual timescales. This sediment-flux gradient suggests that averaged, modern erosion in the western Himalaya is most pronounced at frontal regions, which are characterized by high monsoonal rainfall and thick soil cover. Third, in seven of eight catchments, we find an anticlockwise hysteresis loop of annual sediment flux variations with respect to river discharge, which appears to be related to enhanced glacial sediment evacuation during late summer. Our analysis emphasizes the importance of unconsolidated sediments in the high-elevation sector that can easily be mobilized by hydrometeorological events and higher glacial-meltwater contributions. In future climate change scenarios, including continuous glacial retreat and

  9. The order and volume fill rates in inventory control systems

    DEFF Research Database (Denmark)

    Thorstenson, Anders; Larsen, Christian

    2011-01-01

    This paper differentiates between an order (line) fill rate and a volume fill rate and specifies their performance for different inventory control systems. When the focus is on filling complete customer orders rather than total quantities the order fill rate would be the preferred service level m...

  10. Summary and evaluation of existing geological and geophysical data near prospective surface facilities in Midway Valley, Yucca Mountain Project, Nye County, Nevada

    International Nuclear Information System (INIS)

    Gibson, J.D.; Swan, F.H.; Wesling, J.R.; Bullard, T.F.; Perman, R.C.; Angell, M.M.; DiSilvestro, L.A.

    1992-01-01

    Midway Valley, located at the eastern base of the Yucca Mountain in southwestern Nevada, is the preferred location of the surface facilities for the potential high-level nuclear waste repository at Yucca Mountain. One goal in siting these surface facilities is to avoid faults that could produce relative displacements in excess of 5 cm in the foundations of the waste-handling buildings. This study reviews existing geologic and geophysical data that can be used to assess the potential for surface fault rupture within Midway Valley. Dominant tectonic features in Midway Valley are north-trending, westward-dipping normal faults along the margins of the valley: the Bow Ridge fault to the west and the Paintbrush Canyon fault to the east. Published estimates of average Quaternary slip rates for these faults are very low but the age of most recent displacement and the amount of displacement per event are largely unknown. Surface mapping and interpretive cross sections, based on limited drillhole and geophysical data, suggest that additional normal faults, including the postulated Midway Valley fault, may exist beneath the Quaternary/Tertiary fill within the valley. Existing data, however, are inadequate to determine the location, recency, and geometry of this faulting. To confidently assess the potential for significant Quaternary faulting in Midway Valley, additional data are needed that define the stratigraphy and structure of the strata beneath the valley, characterize the Quaternary soils and surfaces, and establish the age of faulting. The use of new and improved geophysical techniques, combined with a drilling program, offers the greatest potential for resolving subsurface structure in the valley. Mapping of surficial geologic units and logging of soil pits and trenches within these units must be completed, using accepted state-of-the-art practices supported by multiple quantitative numerical and relative age-dating techniques

  11. Sudden disintegration of ice in the glacial-proglacial transition zone of the largest glacier in Austria

    Science.gov (United States)

    Kellerer-Pirklbauer, Andreas; Avian, Michael; Hirschmann, Simon; Lieb, Gerhard Karl; Seier, Gernot; Sulzer, Wolfgang; Wakonigg, Herwig

    2017-04-01

    Rapid deglaciation does not only reveal a landscape which is prone to rapid geomorphic changes and sediment reworking but also the glacier ice itself might be in a state of disintegration by ice melting, pressure relief, crevasse formation, ice collapse or changes in the glacier's hydrology. In this study we considered the sudden disintegration of glacier ice in the glacial-proglacial transition zone of Pasterze Glacier. Pasterze Glacier is a typical alpine valley glacier and covers currently some 16.5 km2 making it to the largest glacier in Austria. This glacier is an important site for alpine mass tourism in Austria related to a public high alpine road and a cable car which enable access to the glacier rather easily also for unexperienced mountaineers. Spatial focus in our research is given on two particular study areas where several ice-mass movement events occurred during the 2015- and 2016-melting seasons. The first study area is a crevasse field at the lower third of the glacier tongue. This lateral crevasse field has been substantially modified during the last two melting seasons particularly because of thermo-erosional effects of a glacial stream which changed at this site from subglacial (until 2015) to glacier-lateral revealing a several tens of meters high unstable ice cliff prone to ice falls of different magnitudes. The second study area is located at the proglacial area. At Pasterze Glacier the proglacial area is widely influenced by dead-ice bodies of various dimensions making this area prone to slow to sudden geomorphic changes caused by ice mass changes. A particular ice-mass movement event took place on 20.09.2016. Within less than one hour the surface of the proglacial area changed substantially by tilting, lateral shifting, and subsidence of the ground accompanied by complete ice disintegration of once-debris covered ice. To understand acting processes at both areas of interest and to quantify mass changes we used field observations, terrain

  12. Compiling geophysical and geological information into a 3-D model of the glacially-affected island of Föhr

    Directory of Open Access Journals (Sweden)

    T. Burschil

    2012-10-01

    Full Text Available Within the scope of climatic change and associated sea level rise, coastal aquifers are endangered and are becoming more a focus of research to ensure the future water supply in coastal areas. For groundwater modelling a good understanding of the geological/hydrogeological situation and the aquifer behavior is necessary. In preparation of groundwater modelling and assessment of climate change impacts on coastal water resources, we setup a geological/hydrogeological model for the North Sea Island of Föhr.

    Data from different geophysical methods applied from the air, the surface and in boreholes contribute to the 3-D model, e.g. airborne electromagnetics (SkyTEM for spatial mapping the resistivity of the entire island, seismic reflections for detailed cross-sections in the groundwater catchment area, and geophysical borehole logging for calibration of these measurements. An iterative and integrated evaluation of the results from the different geophysical methods contributes to reliable data as input for the 3-D model covering the whole island and not just the well fields.

    The complex subsurface structure of the island is revealed. The local waterworks use a freshwater body embedded in saline groundwater. Several glaciations reordered the youngest Tertiary and Quaternary sediments by glaciotectonic thrust faulting, as well as incision and refill of glacial valleys. Both subsurface structures have a strong impact on the distribution of freshwater-bearing aquifers. A digital geological 3-D model reproduces the hydrogeological structure of the island as a base for a groundwater model. In the course of the data interpretation, we deliver a basis for rock identification.

    We demonstrate that geophysical investigation provide petrophysical parameters and improve the understanding of the subsurface and the groundwater system. The main benefit of our work is that the successful combination of electromagnetic, seismic and borehole

  13. Glacial lake outburst floods and fluvial erosion in the Himalaya - insights from the 2016 Bhote Koshi GLOF

    Science.gov (United States)

    Cook, K. L.; Gimbert, F.; Andermann, C.; Hovius, N.; Adhikari, B. R.

    2017-12-01

    The Himalaya is a region of rapid erosion where fluvial processes are assumed to be driven by precipitation delivered during the annual Indian Summer Monsoon. However, the rivers in this region are also subject to catastrophic floods caused by the failure of glacial lake and landslide dams. Because these floods are rarely observed, it has been difficult to isolate their impact on the rivers and adjacent hillslopes, and their importance for the long-term evolution of Himalayan valleys is largely unknown. In July 2016, the Bhotekoshi/Sunkoshi River in central Nepal was hit by a glacial lake outburst flood (GLOF) that caused substantial changes to the channel bed, banks, and adjacent hillslopes, causing at least 26 landslides and an average of 11 m of channel widening. The flood passed through a seismic and hydrological observatory installed along the river in June 2015, and we have used the resulting data to constrain the timing, duration, and bedload transport properties of the outburst flood. The impact of the flood on the river can be further observed with hourly time-lapse photographs, daily measurements of suspended sediment load, repeat lidar surveys, and satellite imagery. The outburst flood affected the river on several timescales. In the short term, it transported large amounts of coarse sediment and restructured the river bed during the hours of the flood pulse itself. Over intermediate timescales it resulted in elevated bedload and suspended load transport for several weeks following the flood. Over longer timescales the flood undercut and destabilized the river banks and hillslopes in a number of locations, leading to bank collapses, slumps, and landslides. Our data indicate that impacts of the GLOF far exceed those driven by the annual summer monsoon, likely due to extremely coarse sediment that armors much of the channel. The relatively frequent occurrence of GLOFs and the extremely high discharges relative to monsoon floods suggest that GLOFs may

  14. Christmas Valley Renewable Energy Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Del Mar, Robert [Oregon Department of Energy, Salem, OR (United States)

    2017-05-22

    In partnership with the Oregon Military Department, the Department of Energy used the award to assess and evaluate renewable resources in a 2,622-acre location in Lake County, central Oregon, leading to future development of up to 200 MW of solar electricity. In partnership with the Oregon Military Department, the Department of Energy used the award to assess and evaluate renewable resources in a 2,622-acre location in Lake County, central Oregon, leading to future development of up to 200 MW of solar electricity. The Oregon Military Department (Military) acquired a large parcel of land located in south central Oregon. The land was previously owned by the US Air Force and developed for an Over-the-Horizon Backscatter Radar Transmitter Facility, located about 10 miles east of the town of Christmas Valley. The Military is investigating a number of uses for the site, including Research and Development (R&D) laboratory, emergency response, military operations, developing renewable energy and related educational programs. One of the key potential uses would be for a large scale solar photovoltaic power plant. This is an attractive use because the site has excellent solar exposure; an existing strong electrical interconnection to the power grid; and a secure location at a moderate cost per acre. The project objectives include: 1. Site evaluation 2. Research and Development (R&D) facility analysis 3. Utility interconnection studies and agreements 4. Additional on-site renewable energy resources analysis 5. Community education, outreach and mitigation 6. Renewable energy and emergency readiness training program for veterans

  15. Geologic Results from the Long Valley Exploratory Well

    Energy Technology Data Exchange (ETDEWEB)

    McConnell, Vicki S.; Eichelberger, John C.; Keskinen, Mary J.; Layer, Paul W.

    1992-03-24

    As a deep well in the center of a major Quaternary caldera, the Long Valley Exploratory Well (LVEW) provides a new perspective on the relationship between hydrothermal circulation and a large crustal magma chamber. It also provides an important test of models for the subsurface structure of active continental calderas. Results will impact geothermal exploration, assessment, and management of the Long Valley resource and should be applicable to other igneous-related geothermal systems. Our task is to use the cuttings and core from LVEW to interpret the evolution of the central caldera region, with emphasis on evidence of current hydrothermal conditions and circulation. LVEW has reached a depth of 2313 m, passing through post-caldera extrusives and the intracaldera Bishop Tuff to bottom in the Mt. Morrison roof pendant of the Sierran basement. The base of the section of Quaternary volcanic rocks related to Long Valley Caldera was encountered at 1800 m of which 1178 m is Bishop Tuff. The lithologies sampled generally support the classic view of large intercontinental calderas as piston-cylinder-like structures. In this model, the roof of the huge magma chamber, like an ill-fitting piston, broke and sank 2 km along a ring fracture system that simultaneously and explosively leaked magma as Bishop Tuff. Results from LVEW which support this model are the presence of intact basement at depth at the center of the caldera, the presence of a thick Bishop Tuff section, and textural evidence that the tuff encountered is not near-vent despite its central caldera location. An unexpected observation was the presence of rhyolite intrusions within the tuff with a cumulative apparent thickness in excess of 300 m. Chemical analyses indicate that these are high-silica, high-barium rhyolites. Preliminary {sup 40}Ar/{sup 39}Ar analyses determined an age of 626 {+-} 38 ka (this paper). These observations would indicate that the intrusions belong to the early post-collapse episode of

  16. 10Be exposure age chronology of the last glaciation of the Roháčská Valley in the Western Tatra Mountains, central Europe

    Science.gov (United States)

    Engel, Zbyněk; Mentlík, Pavel; Braucher, Régis; Křížek, Marek; Pluháčková, Markéta; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim; Aster Team; Arnold, Maurice; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim

    2017-09-01

    10Be exposure ages from moraines and bedrock sites in the Roháčská Valley provide chronology of the last glaciation in the largest valley of the Western Tatra Mts., the Western Carpathians. The minimum apparent exposure age of 19.4 ± 2.1 ka obtained for the oldest sampled boulder and the mean age of 18.0 ± 0.8 ka calculated for the terminal moraine indicate that the oldest preserved moraine was probably deposited at the time of the global Last Glacial Maximum (LGM). The age of this moraine coincides with the termination of the maximum glacier expansion in other central European ranges, including the adjacent High Tatra Mts. and the Alps. The equilibrium line altitude (ELA) of the LGM glacier in the Roháčská Valley, estimated at 1400-1410 m a.s.l., was 50-80 m lower than in the eastern part of the range, indicating a positive ELA gradient from west to east among the north-facing glaciers in the Tatra Mts. Lateglacial glacier expansion occurred no later than 13.4 ± 0.5 ka and 11.9 ± 0.5 ka, as indicated by the mean exposure ages calculated for re-advance moraines. This timing is consistent with the exposure age chronology of the last Lateglacial re-advance in the High Tatra Mts., Alps and lower mountain ranges in central Europe. The ELA in the Roháčská Valley estimated at 1690-1770 m a.s.l. in this period was located 130-300 m lower than in the north-facing valleys in the High Tatra Mts. 10Be exposure ages obtained for a rock glacier constrains the timing of this landform stabilization in the Salatínska Valley and provides the first chronological evidence for the Lateglacial activity of rock glaciers in the Carpathians.

  17. Numerical simulation of ground-water flow through glacial deposits and crystalline bedrock in the Mirror Lake area, Grafton County, New Hampshire

    Science.gov (United States)

    Tiedeman, Claire; Goode, Daniel J.; Hsieh, Paul A.

    1997-01-01

    This report documents the development of a computer model to simulate steady-state (long-term average) flow of ground water in the vicinity of Mirror Lake, which lies at the eastern end of the Hubbard Brook valley in central New Hampshire. The 10-km2 study area includes Mirror Lake, the three streams that flow into Mirror Lake, Leeman's Brook, Paradise Brook, and parts of Hubbard Brook and the Pemigewasset River. The topography of the area is characterized by steep hillsides and relatively flat valleys. Major hydrogeologic units include glacial deposits, composed of till containing pockets of sand and gravel, and fractured crystalline bedrock, composed of schist intruded by granite, pegmatite, and lamprophyre. Ground water occurs in both the glacial deposits and bedrock. Precipitation and snowmelt infiltrate to the water table on the hillsides, flow downslope through the saturated glacial deposits and fractured bedrock, and discharge to streams and to Mirror Lake. The model domain includes the glacial deposits, the uppermost 150m of bedrock, Mirror Lake, the layer of organic sediments on the lake bottom, and streams and rivers within the study area. A streamflow routing package was included in the model to simulate baseflow in streams and interaction between streams and ground water. Recharge from precipitation is assumed to be areally uniform, and riparian evapotranspiration along stream banks is assumed negligible. The spatial distribution of hydraulic conductivity is represented by dividing the model domain into several zones, each having uniform hydraulic properties. Local variations in recharge and hydraulic conductivities are ignored; therefore, the simulation results characterize the general ground-water system, not local details of ground-water movement. The model was calibrated using a nonlinear regression method to match hydraulic heads measured in piezometers and wells, and baseflow in three inlet streams to Mirror Lake. Model calibration indicates that

  18. Flammability of Gas-Filled Polymers

    Directory of Open Access Journals (Sweden)

    Ushkov Valentin Anatol'evich

    2017-09-01

    Full Text Available The regularities of flame propagation on the horizontal surface of gas-filled polymers are considered depending on the concentration of oxygen in the oxidizer flow. The values of the coefficients in the expression describing relationship between the rate of flame propagation on the surface of foams and oxygen concentration are obtained. It was shown that with the mass content of reactive organophosphorus compounds reaching 4.0...5.9%, non-smoldering resole foam plastics with high performance characteristics are obtained. It was found that in order to obtain moderately combustible polyurethane foams based on oxyethylated phosphorus-containing polyols, the phosphorus concentration should not exceed 3 % of mass. To obtain flame-retardant urea-formaldehyde foam cellular plastics, the concentration of phosphorus should not exceed 0.3 % of mass. Physical-mechanical properties and flammability indices of developed gas-filled polymers based on reactive oligomers are presented.

  19. Form Filling with Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2007-01-01

    to the prospects of improving the structural quality, working environment, productivity, and architectural appearance. However, especially in vertical applications there is a great unused potential. Controlling the casting process is important in many different industries such as the metal, plastic, and food...... the framework of Computational Fluid Dynamics (CFD). CFD is applied to simulate the homogeneous form filling characteristics, i.e. the form filling ability and flow patterns, taking into account the rheological properties and casting technique. It is assumed that the rheological properties of SCC follow...... dimensions. For the heterogeneous flow phenomena, this project focusses on the assessment of blocking, which is of special interest in relation to high quality and complicated structures with a dense reinforcement configuration. A phenomenological micro-mechanical model has been developed, which introduces...

  20. Rainwater drained through fully filled pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, B; Koestel, P

    1989-02-01

    The conventional rainwater drainage system according to DIN 1986 always seems to be a point of problemacy in the building services as far as the occupancy of installation shafts and ducts is at stake. The excavation work and the necessary gravity lines are considered to be expensive. The consideration of the necessary slope complicates the installation additionally. Basing on those considerations, the raindraining system with fully filled pipes has been developed. DIN 1986, edition June 1988, part 1, point 6.1.1 allows to install rainwater pipes operated as planned, fully filled without slope. An enterprise specialised in building services investigated all system laws because only by a hydraulically exact balance, the function of the rainwater drainage system operated by negative and positive pressure can be insured. The results of those investigations are integrated in a computer program developed for this purpose.

  1. Fossil Coral Records of ENSO during the Last Glacial Period

    Science.gov (United States)

    Partin, J. W.; Taylor, F. W.; Shen, C. C.; Edwards, R. L.; Quinn, T. M.; DiNezro, P.

    2017-12-01

    Only a handful of paleoclimate records exist that can resolve interannual changes, and hence El Nino/Southern Oscillation (ENSO) variability, during the last glacial period, a time of altered mean climate. The few existing data suggest reduced ENSO variability compared to the Holocene, possibly due to a weaker zonal sea surface temperature gradient across the tropical Pacific and/or a deeper thermocline in the eastern tropical Pacific. Our goal is to add crucial data to this extremely limited subset using sub-annually resolved fossil corals that grew during this time period to reconstruct ENSO. We seek to recover fossil corals from Vanuatu, SW Pacific (16°S, 167°E) with the objective of using coral δ18O to reconstruct changes in the ENSO during and near the Last Glacial Maximum (LGM). Modern δ18O coral records from Vanuatu show a high degree of skill in capturing ENSO variability, making it a suitable site for reconstructing ENSO variability. We have custom designed and are building a drill system that can rapidly core many 0-25 m holes resulting in much more meters of penetration than achieved by previous land-based reef drilling. As the new drill system is extremely portable and can be quickly relocated by workers without landing craft or vehicles, it is time and cost efficient. Because the proposed drilling sites have uplifted extremely fast, 7 mm/year, the LGM shoreline has been raised from 120-140 m depth to within a depth range of 10 below to 20 m above present sea level. This enables all the drilling to be within the time range of interest ( 15-25 ka). A last advantage is that the LGM corals either are still submersed in seawater or emerged only within the last 2000 years at the uplift rate of 7 mm/yr. This greatly reduces the chances of disruption of the original climate signal because sea water is less diagenetically damaging than meteoric water in the mixed, phreatic, or vadose zones. LGM coral records will enable us to compare the proxy variability

  2. PLANETARY PERMO-СARBONIFEROUS ICE AGE – BANK OF PALEONTOLOGICAL AND GEOLOGICAL FACTS FOR DISPROVING THE GLACIAL THEORY

    Directory of Open Access Journals (Sweden)

    V. G. Chuvardinsky

    2017-09-01

    polished and grooved “glacial bed” of the bedrock, as well as roche moutonnée (sheepbacks and fleecy rocks that are associated with the tillites, this is just a clear illustration of tectonic subsurface shear displacements of fault and thrust types. This allows closing the topic about the grand Permo-Carboniferous glaciation. Glaciology. But there is additional material in support of these conclusions – they relate to the glacial theory in the whole. By now, due to the work of glaciologists, geologists, and geophysicists, the dynamics and tendency of glacial drifts, throughout its mass, have been studied. The results of ice through drilling (to the bedrock in Antarctica and Greenland, obtained within the framework of the International Projects, are of great importance. A thorough study of many kilometers of ice columns, as well as the study of vertical ice breaks and the study of ice in tunnels broken through the base of glaciers, produced unexpected results. It turned out that instead of moraine-containing ice mass, entirely filled with huge blocks and boulders (as is customary depicted in diagrams and drawings in the textbooks on general and quaternary geology and geomorphology, only inclusions of sandy-loamy and fine-earth substance are traced in continental ice. Even in the bottom of the glaciers – where it is customary to place a wide basal moraine filled with huge blocks and iron-like boulders, only small lenses and clots of loamy and sandy-loamy substance, and rarely sand grains are fixed. These mineral inclusions are contained in hundredths of a percent and are mainly represented by volcanic ash, microcosmic particles, aeolian dust of distant deserts, rare inclusions of fine-earth terrigenous material, as well as spores and pollen. There’s no need to mention tillites with huge boulders! All that is left for the proponents of the glacial doctrine, who depict decimetric dust-like moraines without boulders. An important function of glaciers is to conserve

  3. Air filled porosity in composting processes

    Energy Technology Data Exchange (ETDEWEB)

    Ruggieri, L.; Gea, T.; Artola, A.; Sanchez, A.

    2009-07-01

    As it is widely known, the composting process consists in the aerobic decomposition of the biodegradable organic matter present in different types of solid wastes. Water and oxygen are necessary for the biological activity of microorganisms involved in the composting process and their availability is directly related to the total and the air filled porosity (AFP). Maintaining adequate AFP level satisfies the oxygen content requirement to achieve the desired composting conditions and thus, tho enhance biological activity. (Author)

  4. Moon - 'Ghost' craters formed during Mare filling.

    Science.gov (United States)

    Cruikshank, D. P.; Hartmann, W. K.; Wood, C. A.

    1973-01-01

    This paper discusses formation of 'pathological' cases of crater morphology due to interaction of craters with molten lavas. Terrestrial observations of such a process are discussed. In lunar maria, a number of small impact craters (D less than 10 km) may have been covered by thin layers of fluid lavas, or formed in molten lava. Some specific lunar examples are discussed, including unusual shallow rings resembling experimental craters deformed by isostatic filling.

  5. Mobile myelographic filling defects: Spinal cysticercosis

    Energy Technology Data Exchange (ETDEWEB)

    Savoiardo, M.; Cimino, C.; Passerini, A.; La Mantia, L.

    1986-03-01

    Cysticercosis usually affects the brain and is easily demonstrated by CT. Spinal cysticercosis is much rarer and is usually diagnosed only at surgery. Myelographic demonstration of multiple rounded filling defects, some of which were mobile, allowed diagnosis of spinal extramedullary cysticercosis in an unsuspected case. The literature on spinal cysticercosis is briefly reviewed. Diagnosis is important in view of the recent development of medical treatment.

  6. The partially filled viscous ring damper.

    Science.gov (United States)

    Alfriend, K. T.

    1973-01-01

    The problem of a spinning satellite with a partially filled viscous ring damper is investigated. It is shown that there are two distinct modes of motion, the nutation-synchronous mode and spin-synchronous mode. From an approximate solution of the equations of motion a time constant is obtained for each mode. From a consideration of the fluid dynamics several methods are developed for determining the damping constant.

  7. Pulse formation of gas-filled counter

    International Nuclear Information System (INIS)

    Iwatani, Kazuo; Teshima, Kazunori; Shizuma, Kiyoshi; Hasai, Hiromi

    1991-01-01

    The pulse formation of gas-filled counter has been calculated by simple models for the proportional and self-quenching streamer (SQS) modes. Calculated pulse shapes of counter output have accurately reproduced the observed ones for both modes. As a result, it is shown that the special density distribution of ion pairs in a streamer can be estimated with the rising part of observed pulse shape, using the model. (author)

  8. Full-waveform inversion: Filling the gaps

    KAUST Repository

    Beydoun, Wafik B.

    2015-09-01

    After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi, UAE. The workshop was organized by SEG, and its partner sponsors were Saudi Aramco (gold sponsor), ExxonMobil, and CGG. Read More: http://library.seg.org/doi/10.1190/tle34091106.1

  9. Air filled porosity in composting processes

    International Nuclear Information System (INIS)

    Ruggieri, L.; Gea, T.; Artola, A.; Sanchez, A.

    2009-01-01

    As it is widely known, the composting process consists in the aerobic decomposition of the biodegradable organic matter present in different types of solid wastes. Water and oxygen are necessary for the biological activity of microorganisms involved in the composting process and their availability is directly related to the total and the air filled porosity (AFP). Maintaining adequate AFP level satisfies the oxygen content requirement to achieve the desired composting conditions and thus, tho enhance biological activity. (Author)

  10. Boron filled siloxane polymers for radiation shielding

    Science.gov (United States)

    Labouriau, Andrea; Robison, Tom; Shonrock, Clinton; Simmonds, Steve; Cox, Brad; Pacheco, Adam; Cady, Carl

    2018-03-01

    The purpose of the present work was to evaluate changes to structure-property relationships of 10B filled siloxane-based polymers when exposed to nuclear reactor radiation. Highly filled polysiloxanes were synthesized with the intent of fabricating materials that could shield high neutron fluences. The newly formulated materials consisted of cross-linked poly-diphenyl-methylsiloxane filled with natural boron and carbon nanofibers. This polymer was chosen because of its good thermal and chemical stabilities, as well as resistance to ionizing radiation thanks to the presence of aromatic groups in the siloxane backbone. Highly isotopically enriched 10B filler was used to provide an efficient neutron radiation shield, and carbon nanofibers were added to improve mechanical strength. This novel polymeric material was exposed in the Annular Core Research Reactor (ACRR) at Sandia National Labs to five different neutron/gamma fluxes consisting of very high neutron fluences within very short time periods. Thermocouples placed on the specimens recorded in-situ temperature changes during radiation exposure, which agreed well with those obtained from our MCNP simulations. Changes in the microstructural, thermal, chemical, and mechanical properties were evaluated by SEM, DSC, TGA, FT-IR NMR, solvent swelling, and uniaxial compressive load measurements. Our results demonstrate that these newly formulated materials are well-suitable to be used in applications that require exposure to different types of ionizing conditions that take place simultaneously.

  11. MORPHOLOGICAL FILLING OF DIGITAL ELEVATION MODELS

    Directory of Open Access Journals (Sweden)

    T. Krauß

    2012-09-01

    Full Text Available In this paper a new approach for a more detailed post processing and filling of digital elevation models (DEMs in urban areas is presented. To reach the required specifications in a first step the errors in digital surface models (DSMs generated by dense stereo algorithms are analyzed and methods for detection and classification of the different types of errors are implemented. Subsequently the classified erroneous areas are handled in separate manner to eliminate outliers and fill the DSM properly. The errors which can be detected in DSMs range from outliers – single pixels or small areas containing extremely high or low values – over noise from mismatches, single small holes to occlusions, where large areas are not visible in one of the images of the stereo pair. To validate the presented method artificial DSMs are generated and superimposed with all different kinds of described errors like noise (small holes cut in, outliers (small areas moved up/down, occlusions (larger areas beneath steep walls and so on. The method is subsequently applied to the artificial DSMs and the resulting filled DSMs are compared to the original artificial DSMs without the introduced errors. Also the method is applied to stereo satellite generated DSMs from the ISPRS Comission 1 WG4 benchmark dataset and the results are checked with the also provided first pulse laser DSM data. Finally the results are discussed, strengths and weaknesses of the approach are shown and suggestions for application and optimization are given.

  12. Topographic registers of paleo-valleys on the southeastern Brazilian continental shelf

    Directory of Open Access Journals (Sweden)

    Luis Américo Conti

    2009-06-01

    Full Text Available The evolution of paleo-incised-valleys in the São Paulo State region of the southeastern Brazilian continental shelf is presented in this study in relation to the post Last Glacial Maximum (LGM sea-level rises based on the submarine topography modeled by a detailed Digital Elevation Model and evidences noted in high resolution seismic profiles. The hypothesis that has guided this study is that the set of paleo-valley characteristics (i.e. the fluvial parameters of modern coastal drainage systems, the topographical shape and dimensions of the valleys and of the subsurface channels may indicate aspects of the relation between the influence of the fluvial and the eustatic variation regime in geomorphological-stratigraphic registers. Models described in the literature sustain the view that faster marine transgressions tend to increase erosion in estuaries, which may explain the lack of registers of paleo-drainage both in topography and the sub-surface in areas with wider shelves. On the other hand, on narrower shelves, with a higher slope angle, the transgression process can preserve, or even enhance, the incised valley registers during shoreface retreat. In the area studied, we observed that the dimensions and form of the continental shelf varies from the northern to the southern part of the area, affecting aspects of the geomorphological registers of the submerged incised valleys.Este trabalho apresenta aspectos da relação entre a evolução da paleo-drenagem e evolução do nível do mar pós Último Máximo Glacial (UMG para a região da plataforma continental do Estado de São Paulo. Para tal, foram analisados modelos topográficos de detalhe da região de Plataforma Continental a partir de Modelos Digitais de Terreno além de dados de subsuperfície obtidos a partir de linhas sísmicas de alta resolução. A hipótese que guiou este trabalho é de que o conjunto de características relativas aos paleo-vales (i.e. sua relação com a rede de

  13. Millennial climatic fluctuations are key to the structure of last glacial ecosystems.

    Directory of Open Access Journals (Sweden)

    Brian Huntley

    Full Text Available Whereas fossil evidence indicates extensive treeless vegetation and diverse grazing megafauna in Europe and northern Asia during the last glacial, experiments combining vegetation models and climate models have to-date simulated widespread persistence of trees. Resolving this conflict is key to understanding both last glacial ecosystems and extinction of most of the mega-herbivores. Using a dynamic vegetation model (DVM we explored the implications of the differing climatic conditions generated by a general circulation model (GCM in "normal" and "hosing" experiments. Whilst the former approximate interstadial conditions, the latter, designed to mimic Heinrich Events, approximate stadial conditions. The "hosing" experiments gave simulated European vegetation much closer in composition to that inferred from fossil evidence than did the "normal" experiments. Given the short duration of interstadials, and the rate at which forest cover expanded during the late-glacial and early Holocene, our results demonstrate the importance of millennial variability in determining the character of last glacial ecosystems.

  14. Millennial climatic fluctuations are key to the structure of last glacial ecosystems.

    Science.gov (United States)

    Huntley, Brian; Allen, Judy R M; Collingham, Yvonne C; Hickler, Thomas; Lister, Adrian M; Singarayer, Joy; Stuart, Anthony J; Sykes, Martin T; Valdes, Paul J

    2013-01-01

    Whereas fossil evidence indicates extensive treeless vegetation and diverse grazing megafauna in Europe and northern Asia during the last glacial, experiments combining vegetation models and climate models have to-date simulated widespread persistence of trees. Resolving this conflict is key to understanding both last glacial ecosystems and extinction of most of the mega-herbivores. Using a dynamic vegetation model (DVM) we explored the implications of the differing climatic conditions generated by a general circulation model (GCM) in "normal" and "hosing" experiments. Whilst the former approximate interstadial conditions, the latter, designed to mimic Heinrich Events, approximate stadial conditions. The "hosing" experiments gave simulated European vegetation much closer in composition to that inferred from fossil evidence than did the "normal" experiments. Given the short duration of interstadials, and the rate at which forest cover expanded during the late-glacial and early Holocene, our results demonstrate the importance of millennial variability in determining the character of last glacial ecosystems.

  15. Glacially derived material in an Inner Mongolian desert lake during Marine Isotope Stage 2

    Digital Repository Service at National Institute of Oceanography (India)

    Selvaraj, K.; Chen, C-T.A; PrakashBabu, C.; Lou, J-Y.; Liu, C-L.; Hsu, K.J.

    Establishing the precise timing of continental glacial dynamics and abrupt high-latitude climate events is crucial to understanding the causes of global climate change. Multi-proxy records in a lake sediment core from arid Inner Mongolia...

  16. Simulated Impact of Glacial Runoff on CO2 Uptake in the Gulf of Alaska

    Science.gov (United States)

    Pilcher, Darren J.; Siedlecki, Samantha A.; Hermann, Albert J.; Coyle, Kenneth O.; Mathis, Jeremy T.; Evans, Wiley

    2018-01-01

    The Gulf of Alaska (GOA) receives substantial summer freshwater runoff from glacial meltwater. The alkalinity of this runoff is highly dependent on the glacial source and can modify the coastal carbon cycle. We use a regional ocean biogeochemical model to simulate CO2 uptake in the GOA under different alkalinity-loading scenarios. The GOA is identified as a current net sink of carbon, though low-alkalinity tidewater glacial runoff suppresses summer coastal carbon uptake. Our model shows that increasing the alkalinity generates an increase in annual CO2 uptake of 1.9-2.7 TgC/yr. This transition is comparable to a projected change in glacial runoff composition (i.e., from tidewater to land-terminating) due to continued climate warming. Our results demonstrate an important local carbon-climate feedback that can significantly increase coastal carbon uptake via enhanced air-sea exchange, with potential implications to the coastal ecosystems in glaciated areas around the world.

  17. Analysis of Mining-induced Valley Closure Movements

    Science.gov (United States)

    Zhang, C.; Mitra, R.; Oh, J.; Hebblewhite, B.

    2016-05-01

    Valley closure movements have been observed for decades in Australia and overseas when underground mining occurred beneath or in close proximity to valleys and other forms of irregular topographies. Valley closure is defined as the inward movements of the valley sides towards the valley centreline. Due to the complexity of the local geology and the interplay between several geological, topographical and mining factors, the underlying mechanisms that actually cause this behaviour are not completely understood. A comprehensive programme of numerical modelling investigations has been carried out to further evaluate and quantify the influence of a number of these mining and geological factors and their inter-relationships. The factors investigated in this paper include longwall positional factors, horizontal stress, panel width, depth of cover and geological structures around the valley. It is found that mining in a series passing beneath the valley dramatically increases valley closure, and mining parallel to valley induces much more closure than other mining orientations. The redistribution of horizontal stress and influence of mining activity have also been recognised as important factors promoting valley closure, and the effect of geological structure around the valley is found to be relatively small. This paper provides further insight into both the valley closure mechanisms and how these mechanisms should be considered in valley closure prediction models.

  18. Early Holocene (8.6 ka) rock avalanche deposits, Obernberg valley (Eastern Alps): Landform interpretation and kinematics of rapid mass movement.

    Science.gov (United States)

    Ostermann, Marc; Sanders, Diethard; Ivy-Ochs, Susan; Alfimov, Vasily; Rockenschaub, Manfred; Römer, Alexander

    2012-10-15

    In the Obernberg valley, the Eastern Alps, landforms recently interpreted as moraines are re-interpreted as rock avalanche deposits. The catastrophic slope failure involved an initial rock volume of about 45 million m³, with a runout of 7.2 km over a total vertical distance of 1330 m (fahrböschung 10°). 36 Cl surface-exposure dating of boulders of the avalanche mass indicates an event age of 8.6 ± 0.6 ka. A 14 C age of 7785 ± 190 cal yr BP of a palaeosoil within an alluvial fan downlapping the rock avalanche is consistent with the event age. The distal 2 km of the rock-avalanche deposit is characterized by a highly regular array of transverse ridges that were previously interpreted as terminal moraines of Late-Glacial. 'Jigsaw-puzzle structure' of gravel to boulder-size clasts in the ridges and a matrix of cataclastic gouge indicate a rock avalanche origin. For a wide altitude range the