WorldWideScience

Sample records for ancient glacial periods

  1. An Atlas of Submarine Glacial Landforms: Modern, Quaternary and Ancient

    Science.gov (United States)

    Jakobsson, M.; Dowdeswell, J. A.; Canals, M.; Todd, B. J.; Dowdeswell, E. K.; Hogan, K. A.

    2014-12-01

    In the past two decades there have been several advances that make the production of an atlas of submarine glacial landforms timely. First is the development of high-resolution imaging technologies; multi-beam echo-sounding or swath bathymetry that allows the detailed mapping of the sea floor at water depths of tens to thousands of metres across continental margins, and 3-D seismic methods that enable the visualisation of palaeo-continental shelves in Quaternary sediments and ancient palaeo-glacial rocks (e.g. Late Ordovician of Northern Africa). A second technological development is that of ice-breaking or ice-strengthened ships that can penetrate deep into the ice-infested waters of the Arctic and Antarctic, to deploy the multibeam systems. A third component is that of relevance - through both the recognition that the polar regions, and especially the Arctic, are particularly sensitive parts of the global environmental system and that these high-latitude margins (both modern and ancient) are likely to contain significant hydrocarbon resources. An enhanced understanding of the sediments and landforms of these fjord-shelf-slope systems is, therefore, of increasing importance to both academics and industry. We are editing an Atlas of Submarine Glacial Landforms that presents a series of individual contributions that describe, discuss and illustrate features on the high-latitude, glacier-influenced sea floor. Contributions are organised in two ways: first, by position on a continental margin - from fjords, through continental shelves to the continental slope and rise; secondly, by scale - as individual landforms and assemblages of landforms. A final section provides discussion of integrated fjord-shelf-slope systems. Over 100 contributions by scientists from many countries contain descriptions and interpretation of swath-bathymetric data from both Arctic and Antarctic margins and use 3D seismic data to investigate ancient glacial landforms. The Atlas will be

  2. Insights into chemical weathering of the upper continental crust from the geochemistry of ancient glacial diamictites

    Science.gov (United States)

    Li, Su; Gaschnig, Richard M.; Rudnick, Roberta L.

    2016-03-01

    Glacial diamictites, with ages ranging from ∼2900 to 0.01 Ma, record the changing composition of the upper continental crust through time (Gaschnig et al., 2014). Li concentrations and isotopic compositions, combined with Pb isotopic compositions, chemical index of alteration (CIA) values and relative Sr concentrations are used here to assess the degree of chemical weathering recorded in these deposits and the origin of this signature. The δ7Li values of most of the diamictites (ranging from -3.9 to +3.5) are lower than those of mantle-derived basalts (+3.7 ± 2, 2σ), and the low δ7Li values are generally accompanied by high CIA and low Sr/Sr∗ values (or Sr depletion factor, Sr/Sr∗ = Sr/(Ce∗Nd)0.5), reflecting a weathering signature that may have derived from pre-depositional, syn-depositional, and/or post-depositional weathering processes. Profiles through three glacial diamictites with relatively high CIA (a fresh road cut of the Neoproterozoic Nantuo Formation (CIA = 62-69), and drill cores through the Paleoproterozoic Timeball Hill (CIA = 66-75) and Duitschland Formations (CIA = 84-91)) do not show evidence of significant post-depositional weathering. High Th/U, reflecting loss of uranium during oxidative weathering, is seen in all Paleozoic and Neoproterozoic diamictites and a few Paleoproterozoic deposits. Pb isotopic systematics suggest that this signature was largely inherited from preexisting crust, although a subset of samples (the Neoproterozoic Konnarock, Paleozoic Dwyka, and several of the Paleoproterozoic Duitschland samples) appears to have experienced post-depositional U loss. Modern glaciomarine sediments record little weathering (CIA = 47, Sr/Sr∗ = 0.7, δ7Li = +1.8), consistent with the cold temperatures accompanying glacial periods, and suggesting that limited syn-depositional weathering has occurred. Thus, the chemical weathering signature observed in ancient glacial diamictites appears to be largely inherited from the upper

  3. Forest contraction in north equatorial Southeast Asia during the Last Glacial Period.

    Science.gov (United States)

    Wurster, Christopher M; Bird, Michael I; Bull, Ian D; Creed, Frances; Bryant, Charlotte; Dungait, Jennifer A J; Paz, Victor

    2010-08-31

    Today, insular Southeast Asia is important for both its remarkably rich biodiversity and globally significant roles in atmospheric and oceanic circulation. Despite the fundamental importance of environmental history for diversity and conservation, there is little primary evidence concerning the nature of vegetation in north equatorial Southeast Asia during the Last Glacial Period (LGP). As a result, even the general distribution of vegetation during the Last Glacial Maximum is debated. Here we show, using the stable carbon isotope composition of ancient cave guano profiles, that there was a substantial forest contraction during the LGP on both peninsular Malaysia and Palawan, while rainforest was maintained in northern Borneo. These results directly support rainforest "refugia" hypotheses and provide evidence that environmental barriers likely reduced genetic mixing between Borneo and Sumatra flora and fauna. Moreover, it sheds light on possible early human dispersal events.

  4. Evidence of strong ocean heating during glacial periods

    Science.gov (United States)

    Zimov, S. A.; Zimov, N.

    2013-12-01

    Numerous hypotheses have addressed glacial-interglacial climatic dynamics, but none of them explain the sharp 25C temperature increase in Greenland in the last deglaciation (Cuffey et al. 1995; Dahl-Jensen et al. 1998). These robust data were obtained through analyzing the temperature profile in the Greenland ice sheet where cold from the last glaciation is preserved in the depth of the glacial sheet. We suggest that during glaciations the ocean accumulated energy: interior ocean water heated up to ~20-30C and during deglaciation this energy is released. In the analogy with reconstructing the ice sheet temperature profiles, the most reliable proof of ocean interior warming during the last glaciation is the heat flux profiles in the bottom sediments. In the final reports based on temperature measurements conducted during the DSDP (Deep Sea Drilling Project) it is stated that heat flux in the bottom sediments doesn't vary with depth and consequently there were no substantial temperature changes in the ocean interior during the last glacial cycle, and heat flux on the surface of the ocean bottom is the geothermal heat flux (Erickson et al., 1975, Hyndman et al., 1987). However, we have critically investigated data in all initial reports of all deep sea drilling projects and have noticed that all temperature data show that heat flow decreases strongly with depth (a minimum of 40 mW/m2), i.e. most of the heat flux detected on the surface of the ocean floor is not the geothermal heat flux but remaining heat that bottom sediments release. Sharp shifts in heat flow are seen within boreholes at depths crossing gas hydrate bottom. All this means that during the last glacial period interior water temperature was on 25-30C degrees warmer. Conversely, in isolated seas heat flow in the sediments shows little change with depth.

  5. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Laxemar

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Rhen, Ingvar (SWECO Environment AB, Falun (Sweden)); Zugec, Nada (Bergab, Goeteborg (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. This report is concerned with the modelling of a repository at the Laxemar-Simpevarp site during periglacial and glacial climate conditions as a comparison to corresponding modelling carried out for Forsmark /Vidstrand et al. 2010/. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle at Laxemar. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 13,000 years. The simulation results comprise pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance and the bedrock hydraulic and transport properties

  6. Comparison of northern and central Greenland ice cores records of methanesulfonate covering the last glacial period

    DEFF Research Database (Denmark)

    Jonsell, U.; Hansson, M. E.; Siggaard-Andersen, M-L-;

    2007-01-01

    Methanesulfonate (MS-) is measured in ice cores with the objective to obtain a proxy record of marine phytoplankton production of dimethylsulfide (DMS). We present a continuous MS- record covering the last glacial period from the North Greenland Ice Core Project (NGRIP) ice core and compare...... this record with the corresponding records previously presented from Greenland and, in particular, with the GISP2 ice core located 320 km south of NGRIP. Despite that the records have similar mean concentrations, their responses to climatic changes during the last glacial period are slightly different. NGRIP...... ice cores. Udgivelsesdato: 31 July...

  7. A warm and poorly ventilated deep Arctic Mediterranean during the last glacial period

    NARCIS (Netherlands)

    Thornalley, D.J.R.; Bauch, H.A.; Gebbie, G.; Guo, W.; Ziegler, M.; Bernasconi, S.M.; Barker, S.; Skinner, L.C.; Yu, J.

    2015-01-01

    Changes in the formation of dense water in the Arctic Ocean and Nordic Seas [the "Arctic Mediterranean" (AM)] probably contributed to the altered climate of the last glacial period. We examined past changes in AM circulation by reconstructing radiocarbon ventilation ages of the deep Nordic Seas over

  8. The Carbon Cycle as the Main Determinant of Glacial-Interglacial Periods

    CERN Document Server

    de la Cuesta, Diego Jiménez; Núñez, Darío; Rumbos, Beatriz; Vergara-Cervantes, Carlos

    2013-01-01

    An intriguing problem in climate science is the existence of Earth's glacial cycle. We show that it is possible to generate these periodic changes in climate by means of the Earth's carbon cycle as the main source factor. The carbon exchange between the Ocean, the Continent and the Atmosphere is modeled by means of a Lotka-Volterra three species system and the resulting atmospheric carbon cycle is used as the unique radiative forcing mechanism. It is shown that the carbon dioxide and temperature paths that are thus obtained have the same qualitative structure as the 100 kyr glacial-interglacial cycles depicted by the Vostok ice core data, reproducing the asymmetries of rapid heating--slow cooling, and short interglacial--long glacial ages.

  9. Groundwater flow modelling of periods with periglacial and glacial climate conditions - Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik (TerraSolve AB, Floda (Sweden)); Follin, Sven (SF GeoLogic AB, Taeby (Sweden)); Zugec, Nada (Bergab, Stockholm (Sweden))

    2010-12-15

    As a part of the license application for a final repository for spent nuclear fuel at Forsmark, the Swedish Nuclear Fuel and Waste Management Company (SKB) has undertaken a series of groundwater flow modelling studies. These represent time periods with different hydraulic conditions and the simulations carried out contribute to the overall evaluation of the repository design and long-term radiological safety. The groundwater flow modelling study reported here comprises a coupled thermal-hydraulic-chemical (T-H-C) analysis of periods with periglacial and glacial climate conditions. Hydraulic-mechanical (H-M) issues are also handled but no coupled flow modelling is done. The objective of the report is to provide bounding hydrogeological estimates at different stages during glaciation and deglaciation of a glacial cycle for subsequent use in safety assessment applications within SKB's project SR-Site. Three cases with different climate conditions are analysed here: (i) Temperate case, (ii) Glacial case without permafrost, and (iii) Glacial case with permafrost. The glacial periods are transient and encompass approximately 19,000 years. The simulation results comprise residual fluid pressures, Darcy fluxes, and water salinities, as well as advective transport performance measures obtained by particle tracking such as flow path lengths, travel times and flow-related transport resistances. The modelling is accompanied by a sensitivity study that addresses the impact of the following matters: the direction of the ice sheet advance, the speed of the ice sheet margin, the bedrock hydraulic and transport properties, the temperature at the ice-subsurface interface close to the ice sheet margin, and the initial hydrochemical conditions.

  10. Tri-dimensional Model of the Radovna Glacier from the Last Glacial Period

    Directory of Open Access Journals (Sweden)

    Luka Serianz

    2016-12-01

    Full Text Available The Radovna River Valley is located in the northwest of Slovenia, in the Julian Alps, and bounded by two plateaus – Pokljuka in the south and Mežakla in the north. Typical geological and geomorphological shapes in the valley indicate several glacial stages in the Pleistocene. As a result of glacial activity and river outflw, typical glacial and river terraces can be observed throughout the valley, especially in its lower and middle regions. The paper deals with the Radovna Glacier from the last glacial period, the existence of which is evidenced by certain remaining geomorphological features in the valley. Little investigative research on the Radovna Glacier, on its activity and extent, has been done in recent decades; the little that has been done has only featured the glacier as a secondary or incidental subject of research on the neighbouring Dolinka and Bohinj Glaciers. Both numerical modelling and fild surveying were used for the reconstruction model, with work based on previous experiences and observations of hydrogeological conditions in the Radovna Valley. However, it must be emphasized that the model is only validated based on a few remaining traces of the glacier’s activity.

  11. Periodic orbits for a discontinuous vector field arising from a conceptual model of glacial cycles

    Science.gov (United States)

    Walsh, James; Widiasih, Esther; Hahn, Jonathan; McGehee, Richard

    2016-06-01

    Conceptual climate models provide an approach to understanding climate processes through a mathematical analysis of an approximation to reality. Recently, these models have also provided interesting examples of nonsmooth dynamical systems. Here we develop a new conceptual model of glacial cycles consisting of a system of three ordinary differential equations defining a discontinuous vector field. Our model provides a dynamical systems framework for a mechanism previously shown to play a crucial role in glacial cycle patterns, namely, an increased ice sheet ablation rate during deglaciations. We use ad hoc singular perturbation techniques to prove the existence of a large periodic orbit crossing the discontinuity boundary, provided the ice sheet edge moves sufficiently slowly relative to changes in the snow line and temperature. Numerical explorations reveal the periodic orbit exists when the time constant for the ice sheet edge has more moderate values.

  12. Tracing the secular evolution of the UCC using the iron isotope composition of ancient glacial diamictites

    Science.gov (United States)

    Liu, X. M.; Gaschnig, R. M.; Rudnick, R. L.; Hazen, R. M.; Shahar, A.

    2015-12-01

    Iron is the fourth most abundant element in the continental crust and influences global climate and biogeochemical cycles in the ocean1. Continental inputs, including river waters, sediments and atmospheric dust are dominant sources (>95%) of iron into the ocean2. Therefore, understanding how continental inputs may have changed through time is important in understanding the secular evolution of the marine Fe cycle. We analysed the Fe isotopic composition of twenty-four glacial diamictite composites, upper continental crust (UCC) proxies, with ages ranging from the Mesoarchean to the Paleozoic eras to characterize the secular evolution of the UCC. The diamictites all have elevated chemical index of alteration (CIA) and other characteristics of weathered regolith (e.g., strong depletion in soluble elements such as Sr), which they inherited from their upper crustal source region3. δ56Fe in the diamictite composites range from -0.59 to +0.23‰, however, most diamictites cluster with an average δ56Fe of 0.11± 0.20 (2s), overlapping juvenile continental material such as island arc basalts (IABs), which show a narrow range in δ56Fe from -0.04 to +0.14 ‰4. There is no obvious correlation between δ56Fe of the glacial diamictites and the CIA, except that the diamictite with the lowest δ56Fe at -0.59 ‰ also has the highest CIA = 89 (the Paleoproterozoic Makganyene Fm.). The data suggest that the Fe isotope compositions in the upper continental crust did not vary throughout Earth history. Interestingly, chemical weathering and sedimentary transport likely play only a minor role in producing Fe isotope variations in the upper continental crust. Anoxic weathering pre-GOE (Great Oxidation Event) does not seem to generate different Fe isotopic signatures from the post-GOE oxidative weathering environment in the upper continental crust. Therefore, large Fe isotopic fractionations observed in various marine sedimentary records are likely due to other processes occurring

  13. Onset of oxidative weathering of continents recorded in the geochemistry of ancient glacial diamictites

    Science.gov (United States)

    Gaschnig, Richard M.; Rudnick, Roberta L.; McDonough, William F.; Kaufman, Alan J.; Hu, Zhaochu; Gao, Shan

    2014-12-01

    Glacial diamictites deposited in the Mesoarchean, Paleoproterozoic, Neoproterozoic, and Paleozoic eras record temporal variations in their average compositions that reflect the changing composition of the upper continental crust (UCC). Twenty six of the 27 units studied show elevated chemical index of alternation (CIA) and low Sr abundances, regardless of their age, documenting pervasive weathering of the average UCC. Lower abundances of transition metals reflect a shift towards more felsic crustal compositions after the Archean. Superimposed on this chemical difference is the signal of the rise of oxidative weathering of the continents, recorded by changes in the absolute and relative abundances of the redox sensitive elements Mo and V. Neoproterozoic and Paleozoic diamictites show pervasive depletion in Mo and V, reflecting their loss from the continents due to increasing intensity of oxidative weathering, as also recorded in some of the Paleoproterozoic diamictites. A few of the Paleoproterozoic diamictites deposited after the Great Oxidation Event show no depletion in Mo and V (e.g., Gowganda), but such signatures could be inherited from their provenance. In contrast, the pre-GOE Duitschland diamictite (ca. 2.3-2.5 Ga) from South Africa reveals evidence of intense oxidative weathering (i.e., large depletions in Mo), supporting a growing body of observations showing the presence of measurable atmospheric oxygen prior to permanent loss of the mass independent fractionation signal in sulfur isotopes.

  14. Compositional evolution of the upper continental crust through time, as constrained by ancient glacial diamictites

    Science.gov (United States)

    Gaschnig, Richard M.; Rudnick, Roberta L.; McDonough, William F.; Kaufman, Alan J.; Valley, John W.; Hu, Zhaochu; Gao, Shan; Beck, Michelle L.

    2016-08-01

    The composition of the fine-grained matrix of glacial diamictites from the Mesoarchean, Paleoproterozoic, Neoproterozoic, and Paleozoic, collected from four modern continents, reflects the secular evolution of the average composition of the upper continental crust (UCC). The effects of localized provenance are present in some cases, but distinctive geochemical signatures exist in diamictites of the same age from different localities, suggesting that these are global signatures. Archean UCC, dominated by greenstone basalts and to a lesser extent komatiites, was more mafic, based on major elements and transition metal trace elements. Temporal changes in oxygen isotope ratios, rare earth elements, and high field strength elements indicate that the UCC became more differentiated and that tonalite-trondhjemite-granodiorite suites became less important with time, findings consistent with previous studies. We also document the concentrations of siderophile and chalcophile elements (Ga, Ge, Cd, In, Sn, Sb, W, Tl, Bi) and lithophile Be in the UCC through time, and use the data for the younger diamictites to construct a new estimate of average UCC along with associated uncertainties.

  15. Future Implications of Climate-driven Vegetation Change in North America Since the Last Glacial Period

    Science.gov (United States)

    Nolan, C.; Jackson, S. T.; Overpeck, J. T.; Betancourt, J. L.

    2013-12-01

    Climate projections for the next century include increases in average global temperature that are likely to cause changes in plant community composition and structure across the globe. Characterizing the magnitude of impending climate-driven vegetation changes is important for conservation planning and adaptation, but difficult because climate-driven vegetation change is the result of interacting processes operating on multiple spatial and temporal scales. Paleoecological records from all the vegetated continents offer a proxy record of the vegetation during the last glacial period (defined here as 14,000 to 21,000 years before present). Assessment of the degree of change between glacial-age and modern vegetation provides a metric for assessing impacts of future climate change. A global comparison is underway, in which regional experts are compiling all available pollen and plant macrofossil records with coverage during the last glacial period, and comparing glacial-age vegetation with modern (or late Holocene) vegetation, assessing the magnitude of compositional and structural change. Here we present results from North America (excepting Beringia). Nearly all sites assessed show large changes in composition and structure, all attributable to climate change associated with a sub-continental annual surface air warming of ca. 4 to 10+ °C. Current rates of atmospheric greenhouse gas emissions promise comparable magnitudes of climate change over the next one to two centuries, and at a rate much faster than over the last deglaciation. Our results thus suggest that this future climate change will drive major changes in vegetation distributions everywhere in North America.

  16. Climate change since the last glacial period in Lebanon and the persistence of Mediterranean species

    Science.gov (United States)

    Cheddadi, R.; Khater, C.

    2016-10-01

    In this study, we quantified the mean January temperature (Tjan) and both winter (Pw) and summer (Ps) precipitation from three fossil pollen records from Lebanon. Tjan showed a strong correlation with the global temperature changes retrieved in the NGRIP Greenland ice core. The amplitude of ca. 8 °C between the Younger Dryas (YD) period and the Holocene is coherent with climate reconstructions from the Eastern Mediterranean. The overall amount of precipitation was also lower during the YD than during the Holocene but the contrast between Pw and Ps was much more reduced (less than 2 times) during the YD than during the Holocene (up to 8 times). Such different seasonal contrast compare to the present day is coherent with some climate proxies from the Levant that tend to indicate the presence of moisture during the last glacial period. In effect, the low Pw during the YD reflects the replacement of the forest ecosystem by a more shrubby or herbaceous vegetation. Concomitantly, the occurrence of an amount of precipitation higher than the current one during the summer season, along with a reduced evaporation, due to lower temperature, may have contributed to some local observed high lake levels in the area. During the last glacial period, Lebanon was not under a typical Mediterranean climate such as the one we know today, i.e. with a strong precipitation and temperature contrast between summer and winter seasons, but rather under a less contrasted climate. Mediterranean species persisted in this area due to the low amplitude of temperature change between the last glacial period and the Holocene as well as to an availability of moisture throughout the year instead of an occurrence mainly during the winter season as is the case today.

  17. Molecular genetic analysis of Dongzhou-period ancient human of Helingeer in Inner Mongolia, China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The mtDNA hypervariable region I (HVR-I) of 10 ancient individuals from Dongzhou-period ancient human populations in Helingeer county of Inner Mongolia were amplified and sequenced to investigate the genetic structure. The relationships between the ancient population and related extant populations, as well as its possible origin at the molecular level, were also studied. Moreover, phylogenetic analysis and multi-dimensional scaling analysis were also performed based on the mtDNA data of the ancient population in Helingeer and the related Eurasian population. The results showed that the ancient population in Helingeer were closer to the northern Asian populations than to the other compared populations in matrilineal lineage. Combining the research results of archaeology and anthropology as well as molecular biology, we inferred that they were nomads who migrated from Mongolia plateau and cis-Baikal region to Helingeer in Inner Mongolia, China.

  18. Periodic Orbits for a Discontinuous Vector Field Arising from a Conceptual Model of Glacial Cycles

    CERN Document Server

    Walsh, James; Hahn, Jonathan; McGehee, Richard

    2015-01-01

    Conceptual climate models provide an approach to understanding climate processes through a mathematical analysis of an approximation to reality. Recently, these models have also provided interesting examples of nonsmooth dynamical systems. Here we discuss a conceptual model of glacial cycles consisting of a system of three ordinary differential equations defining a discontinuous vector field. We show that this system has a large periodic orbit crossing the discontinuity boundary. This orbit can be interpreted as an intrinsic cycling of the Earth's climate giving rise to alternating glaciations and deglaciations.

  19. The vegetation and climate during the Last Glacial Cold Period, northern South Island, New Zealand

    Science.gov (United States)

    Callard, S. Louise; Newnham, Rewi M.; Vandergoes, Marcus J.; Alloway, Brent V.; Smith, Carol

    2013-08-01

    Pollen assemblages from Howard Valley, South Island, New Zealand, were used to reconstruct the palaeovegetation and infer past climate during the period ca 38-21 cal. ka, which encompasses the Marine Isotope Stage (MIS) 3/2 transition and Last Glacial Cold Period (LGCP). A glacier occupied the upper Howard Valley during the Last Glacial, whilst extensive glaciofluvial outwash surfaces were constructed in the lower valley. Episodic periods of fluvial aggradation and incision have produced a complex sequence of terraces flanking the main Howard River and its tributaries. Sedimentary sequences from three exposed valley fills, sampled for palynological analysis and radiocarbon dating, consist of a complex vertical and lateral arrangement of coarse textured cobbly sandy gravels interbedded with organic-rich silt deposits. Palynology of these organic-rich horizons was directly compared to an existing beetle record from these same horizons. During late MIS 3 the site was dominated by marshy shrubland vegetation interspersed with mixed beech forest, indicating temperatures ˜2-3 °C cooler than present. Climate cooling began as early as 35.7 cal. ka and coincides with evidence of cooling from other sites in New Zealand, South America and with an Antarctic cooling signature. A three phase vegetation and inferred climate pattern occurs at the site during the LGCP beginning with a transition to an alpine/sub-alpine grassland comparable to communities growing near treeline today marking the change to glacial conditions before 31 cal. ka. A small increase in tree abundance between ca 25.8 and 22.7 cal. ka suggests minor climate amelioration during the mid-LGCP. During this phase, a possible volcanically induced vegetation disruption caused by the deposition of the Kawakawa Tephra at 25 cal. ka is evident in the pollen record. This is followed by a further decline in tree pollen and increase in alpine grassland and herb pollen indicating further deterioration of conditions and a

  20. The Olympic Games as reflection conditions of development Ancient Greek civilization in Hellenism period

    Directory of Open Access Journals (Sweden)

    Kasianenko Ol'ga Gennadievna

    2009-02-01

    Full Text Available The author has realized the historical analysis of the Olympic Games at consideration the conditions of Ancient Greek civilization development in Hellenism period. Had presented the division into the periodization of Greek civilization development in which had learned a major changes in the world-view of Hellenes under the A. Macedonian influence, notably: professionalization of sport and gradual fading of ideals, making basis of olympism, and also Christianity following late which results in the decline of the Olympic Games.

  1. Periodicity in a Conceptual Model of Glacial Cycles in the Absence of Milankovitch Forcing

    Science.gov (United States)

    Hahn, J.; Walsh, J.; Widiasih, E.; McGehee, R.

    2015-12-01

    Previously, McGehee and Widiasih coupled Budyko's Energy Balance Model with dynamics of a latitudinal ice-line incorporating the albedo feedback effect. They reduced this model to a two-dimensional equation of global mean temperature and a latitudinal ice-line. With this conceptual model, we now include dynamics of the ablation and accumulation of ice, to form a three-dimensional system that partitions the regions of the Earth latitudinally into an accumulation zone, ablation zone, and ice-free zone. Motivated by the findings of Abe-Ouchi et al that the fast retreat of ice-sheets is due to an increased rate of ablation via the effects of delayed isostatic rebound, we incorporate a simple switching mechanism to the model which increases the rate of ablation during periods of glacial retreat. This forms a discontinuous system of the Earth's temperature and ice-volume in which we find a stable periodic orbit. This can be interpreted as a intrinsic cycling of the Earth's climate in the absence of Milankovitch forcing.

  2. Ancient Tibetan Manuscripts of the Tubo Period Recoverd form Dunhuang: Its Historical-Material Value in the Tibetan Studies

    Institute of Scientific and Technical Information of China (English)

    KalzangGyal

    2004-01-01

    Ancient Tibetan documents of the Tubo period are amongst those discovered in the Mogao Grottoes at Dunhuang in i9oo. As handwritten documents in the ancient Tibetan language of the Tubo period, they are an important part of the international Dunhuang study and indispensable to Tibetology. Incomplete statistics

  3. Interhemispheric anti-phasing of rainfall during the last glacial period

    Science.gov (United States)

    Wang, Xianfeng; Auler, Augusto S.; Edwards, R. Lawrence; Cheng, Hai; Ito, Emi; Solheid, Maniko

    2006-12-01

    We have obtained a high-resolution oxygen isotopic record of cave calcite from Caverna Botuverá (27°13'S, 49°09'W), southern Brazil, which covers most of the last 36 thousand years (ka), with an average resolution of a few to several decades. The chronology was determined with 46 U/Th ages from two stalagmites. Tests for equilibrium conditions show that oxygen isotopic variations are primarily caused by climate change. We interpret our record in terms of meteoric precipitation changes, hence the variability of South American Monsoon (SAM) intensity. The oxygen isotopic profile broadly follows local insolation changes and shows clear millennial-scale variations during the last glacial period with amplitudes as large as 3‰ but with smaller centennial-scale shifts (<1‰) during the Holocene. The overall record is strikingly similar to, but strongly anti-correlated with, a number of records from the Northern Hemisphere. We compared our record to other precisely dated contemporaneous records from Hulu Cave eastern China. Minima in δ18O (wet periods, intense SAM) at our site are synchronous with maxima in δ18O (dry periods, weak East Asian Monsoon, EAM) in eastern China (within precise dating errors) and vice versa. This anti-phased precipitation relationship between two low-latitude locations may be interhemispheric in extent, based on comparison with records from other sites. Precipitation anti-phasing may be related to north-south shifts in the mean position of the intertropical convergence zone (ITCZ) and asymmetry in Hadley circulation in two hemispheres, associated not with seasonal changes as observed today, but with millennial-scale climate shifts. The millennial-scale atmospheric see-saw patterns that we observe could have important controls and feedbacks on climate within hemispheres because of water vapor's greenhouse properties.

  4. Palaeoenvironments of insular Southeast Asia during the Last Glacial Period: a savanna corridor in Sundaland?

    Science.gov (United States)

    Bird, Michael I.; Taylor, David; Hunt, Chris

    2005-11-01

    Consideration of a range of evidence from geomorphology, palynology, biogeography and vegetation/climate modelling suggests that a north-south 'savanna corridor' did exist through the continent of Sundaland (modern insular Indonesia and Malaysia) through the Last Glacial Period (LGP) at times of lowered sea-level, as originally proposed by Heaney [1991. Climatic Change 19, 53-61]. A minimal interpretation of the size of this corridor requires a narrow but continuous zone of open 'savanna' vegetation 50-150 km wide, running along the sand-covered divide between the modern South China and Java Seas. This area formed a land bridge between the Malaysian Peninsula and the major islands of Sumatra, Java and Borneo. The savanna corridor connected similar open vegetation types north and south of the equator, and served as a barrier to the dispersal of rainforest-dependent species between Sumatra and Borneo. A maximal interpretation of the available evidence is compatible with the existence of a broad savanna corridor, with forest restricted to refugia primarily in Sumatra, Borneo and the continental shelf beneath the modern South China Sea. This savanna corridor may have provided a convenient route for the rapid early dispersal of modern humans through the region and on into Australasia.

  5. The key role of topography in altering North Atlantic atmospheric circulation during the last glacial period

    Directory of Open Access Journals (Sweden)

    F. S. R. Pausata

    2011-10-01

    Full Text Available The Last Glacial Maximum (LGM; 21 000 yr before present was a period of low atmospheric greenhouse gas concentrations, when vast ice sheets covered large parts of North America and Europe. Paleoclimate reconstructions and modeling studies suggest that the atmospheric circulation was substantially altered compared to today, both in terms of its mean state and its variability. Here we present a suite of coupled model simulations designed to investigate both the separate and combined influences of the main LGM boundary condition changes (greenhouse gases, ice sheet topography and ice sheet albedo on the mean state and variability of the atmospheric circulation as represented by sea level pressure (SLP and 200-hPa zonal wind in the North Atlantic sector. We find that ice sheet topography accounts for most of the simulated changes during the LGM. Greenhouse gases and ice sheet albedo affect the SLP gradient in the North Atlantic, but the overall placement of high and low pressure centers is controlled by topography. Additional analysis shows that North Atlantic sea surface temperatures and sea ice edge position do not substantially influence the pattern of the climatological-mean SLP field, SLP variability or the position of the North Atlantic jet in the LGM.

  6. Release of Methane from Bering Sea Sediments During the Last Glacial Period

    Energy Technology Data Exchange (ETDEWEB)

    Mea Cook; Lloyd Keigwin

    2007-11-30

    Several lines of evidence suggest that during times of elevated methane flux the sulfate-methane transition zone (SMTZ) was positioned near the sediment-water interface. We studied two cores (from 700 m and 1457 m water depth) from the Umnak Plateau region. Anomalously low d13C and high d18O in benthic and planktonic foraminifera in these cores are the consequence of diagenetic overgrowths of authigenic carbonates. There are multiple layers of authigenic-carbonate-rich sediment in these cores, and the stable isotope compositions of the carbonates are consistent with those formed during anaerobic oxidation of methane (AOM). The carbonate-rich layers are associated with biomarkers produced by methane-oxidizing archaea, archaeol and glyceryl dibiphytanyl glyceryl tetraether (GDGT). The d13C of the archaeol and certain GDGTs are isotopically depleted. These carbonate- and AOM-biomarker-rich layers were emplaced in the SMTZ during episodes when there was a high flux of methane or methane-rich fluids upward in the sediment column. The sediment methane in the Umnak Plateau region appears to have been very dynamic during the glacial period, and interacted with the ocean-atmosphere system at millennial time scales. The upper-most carbonate-rich layers are in radiocarbon-dated sediment deposited during interstitials 2 and 3, 28-20 ka, and may be associated with the climate warming during this time.

  7. Increased dust deposition in the Pacific Southern Ocean during glacial periods

    Science.gov (United States)

    Lamy, Frank; Gersonde, Rainer; Winckler, Gisela; Esper, Oliver; Jaeschke, Andrea; Kuhn, Gerhard; Ullermann, Johannes; Martinez-Garcia, Alfredo; Lambert, Fabrice; Kilian, Rolf

    2014-05-01

    Dust deposition across the Southern Ocean plays a critical role for marine biological production through iron fertilization and is supposed to control a significant fraction of glacial-interglacial atmospheric CO2 changes. However, in the Pacific, the largest Southern Ocean sector, reliable sediment records are sparse and climate models mostly indicate low dust deposition both for modern times and the last glacial maximum. Here, we present comprehensive data-sets of dust supply based on the analysis of sediment records recently retrieved across the Pacific Southern Ocean. The shape and glacial/interglacial pattern of lithogenic sediment input records in the western and central sector reveals strong similarities to dust records from Antarctica and the South Atlantic. Though our new data document substantial sediment redistribution, glacial dust mass accumulation rates corrected for sediment focusing exceed interglacial values by a factor of ~3. The first-order changes in Subantarctic biological productivity largely follow increased dust supply during glacials. Taken together our new sediment records document a substantial glacial dust supply from Australian and New Zealand sources to the Pacific SO sector eastward to at least 125°W. Such enhancement of dust supply is consistent with stronger aridity in Australia and a glacial dust source in New Zealand. Although the most likely dust source for the South Pacific is Australia/New Zealand, the glacial/interglacial pattern and timing of lithogenic sediment deposition is similar to dust records from Antarctica and the South Atlantic dominated by Patagonian sources. These similarities imply large-scale common climate forcings such as latitudinal shifts of the southern westerlies and regionally enhanced glaciogenic dust mobilization in New Zealand and Patagonia.

  8. Analysis of the ancient river system in Loulan period in Lop Nur region

    Science.gov (United States)

    Zhu, Jianfeng; Jia, Peng; Nie, Yueping

    2010-09-01

    The Lop Nur region is located in the east of the Tarim Basin. It has served as the strategic passage and communication hub of the Silk Road since Han Dynasty. During Wei-Jin period, the river system there was well developed and the ancient city of Loulan was bred there. In this study, GIS is used to accomplish automatic extraction of the river course in the Lop Nur region at first using ArcGIS. Then the RCI index is constituted to extract ancient river course from Landsat ETM image with band 3 and band 4. It is concluded that the north river course of Peacock River conformed before the end of the 4th century AD according to the distribution of the entire river course of the Lop Nur region. Later, the Peacock River changed its way to south to Tarim River, and flowed into Lop Nur along the direction paralleling Altun Mountain from west to east. It was the change of the river system that mainly caused the decrease in water supply around ancient city of Loulan before the end of 4th century. The ancient city of Loulan has been gradually ruined in the sand because of the absence of water supply since then.

  9. Impact of Continental Ice Sheet Topography on the Pacific ITCZ During the Last Glacial Period

    Science.gov (United States)

    Lee, S.; Chiang, J. C.; Chang, P.

    2011-12-01

    The Tropical Pacific underwent profound climate change during the Pleistocene ice age variations, marked by cooler sea surface temperature (SST) and changes in hydrological cycle. Studies have shown that the meridional position of the marine Intertropical Convergence Zone (ITCZ) is sensitive to SST gradient changes, and models have demonstrated the Pacific ITCZ shift in response to surface albedo changes and high-latitude Atlantic SST cooling in a glacial climate. However, the tropical Pacific climate response to a full range Last Glacial Maximum (LGM) forcing has yet to be systematically explored. This modeling study investigates the impacts of changes in continental ice sheet topography on the position of Pacific ITCZ in a glacial climate. Simulations using an AGCM coupled to a reduced-gravity ocean where the LGM ice sheet was successively increased from zero thickness to 100% suggest that continental ice sheet growth can lead to significant changes in the tropical Pacific climate, including a reduction in the zonal SST gradient, a southward shift of the ITCZ, and a strengthening (weakening) of the mean-annual northern (southern) hemisphere Hadley circulation. We find a progressive southward displacement of the tropical Pacific rain belt in response to the topographic effect of northern hemisphere continental ice sheets growth, a mechanism distinctly different from the cooling influence by the ice sheet albedo on the ITCZ that had been previously discussed in the literature. Our results suggest that ice-sheet topographic forcing had a significant impact on the tropical Pacific coupled ocean-atmosphere climate during glacial-interglacial cycles.

  10. Periodic Glacial Lake Outburst Floods threatening the oldest Buddhist monastery in north-west Nepal

    Directory of Open Access Journals (Sweden)

    J. Kropáček

    2014-11-01

    Full Text Available Since 2004 Halji Village, home of the oldest Buddhist Monastery in north-west Nepal has suffered from recurrent Glacial Lake Outburst Floods (GLOFs. Studies of recent satellite images identified a supra-glacial lake, located at a distance of 6.5 km from the village, as a possible source of the flood. During a field survey in 2013, the finding was confirmed and several entrances to en-glacial conduits which are draining the lake were found. The topography of the lake basin was then mapped by combining Differential Global Positioning System (DGPS measurements with a Structure From Motion (SFM approach from terrestrial photographs. From this model the maximum filling capacity of the lake has been estimated as 1.06 × 106 m3 with a maximum discharge of 77.8 m3 s−1 calculated using an empirical relation. The flooded area in the valley has been estimated by employing a raster-based hydraulic model considering six scenarios of discharge volume and surface roughness. To understand the changes in glacier geometry in the last decade the thinning and retreat of Halji Glacier have been analysed by geodetic mass balance measurements and a time series of satellite images respectively. The GLOF occurrences have further been correlated with cumulative temperature and cumulative liquid precipitation calculated from the High Asia Reanalysis (HAR dataset. Finally, effective mitigation measures and adaption strategies for Halji village have been discussed.

  11. VARIATION INKINDS OF PENALTY STIPULATEDBY THE ANCIENT RUS’ LEGISLATION AND IN THE PERIOD OF FEUDAL DISUNITY

    Directory of Open Access Journals (Sweden)

    Inna Andreevna PODROYKINA

    2014-01-01

    Full Text Available The paper explored the legislation that emerged in the Ancient Rus and over the period of feudal disunity, in order to identify specifics of the system of penalty estab-lished, and factors having affected the setting up of, for probable application of the used-to-be knowhow further in law-making. The author has traced emergence of the in-public principle in punishment, as well as the principle of private responsibility, and demonstrated the range of penal measures being common for legal practices of that period, and observed penal measures that were specified for such and such crime, those put on the grounds of variation in kinds of penalty.

  12. Mössbauer studies on ancient chinese pottery of Yangshao Culture Period

    Science.gov (United States)

    Yu, Zhengfang; Zheng, Qi; Zheng, Yufang

    1988-12-01

    Eleven pieces of ancient Chinese pottery (4770 B.C. 2960 B.C.) of Yangshao Culture Period collected from the Xi'an area have been studied by means of Mössbauer spectroscopy. The samples were refired up to 1100°C in steps of 100°C for 2h in air. The highest temperature up to which the Mössbauer pattern remains basically unchanged can be identified with the original firing temperature. The result indicates that the firing temperatures for most of the sherds were between 900 1000°C. The function of the grit contained in the pottery has been discussed. The crimson and reddish painted materials on the surface of sherds have been studied, respectively. The first appearance of pottery can probably be traced back to an even earlier period.

  13. Lithostratigraphy and paleoceanography in the Chukchi Rise of the western Arctic Ocean since the last glacial period

    Science.gov (United States)

    Park, Kwangkyu; Ohkushi, Ken'ichi; Cho, Hyen Goo; Khim, Boo-Keun

    2017-03-01

    Paleoceanographic multi-proxies were investigated from two piston cores PC01 and PC04, along with two pilot cores PL01 and PL04, collected from the Chukchi Rise in the western Arctic Ocean during the R/V Mirai Cruise MR09-03. Both cores were composed of three lithologic units (Unit I: the Holocene brownish sandy mud, Unit II: the deglacial IRD layer, and Unit III: the glacial and gray thick mud with intervened IRD layers). The age estimate of the core units were decided by AMS 14C dates and confirmed by the correlation of the geochemical properties and ice-rafted debris (IRD) pattern with the well-dated core (P2) in the study area. The geochemical, isotopic, and mineralogical properties indicate different paleoceanographic conditions of three lithologic units in the Chukchi Rise: low primary production during the glacial period (Unit III), high terrigenous contribution during the deglacial period (Unit II), and increase in diatom productivity during the late Holocene (Unit I). In particular, most IRDs were specified as detrital carbonates (calcites and dolomites) by SEM-EDS examination. The sediment source from the northern North America and the transport pathway by the Beaufort Gyre were confirmed by the isotopic signature of bulk IRDs and high kaolinite content of fine-grained particles.

  14. Shifting Milestones of Natural Sciences: The Ancient Egyptian Discovery of Algol's Period Confirmed

    Science.gov (United States)

    Jetsu, Lauri; Porceddu, Sebastien

    2015-12-01

    The Ancient Egyptians wrote Calendars of Lucky and Unlucky Days that assigned astronomically influenced prognoses for each day of the year. The best preserved of these calendars is the Cairo Calendar (hereafter CC) dated to 1244-1163 B.C. We have presented evidence that the 2.85 days period in the lucky prognoses of CC is equal to that of the eclipsing binary Algol during this historical era. We wanted to find out the vocabulary that represents Algol in the mythological texts of CC. Here we show that Algol was represented as Horus and thus signified both divinity and kingship. The texts describing the actions of Horus are consistent with the course of events witnessed by any naked eye observer of Algol. These descriptions support our claim that CC is the oldest preserved historical document of the discovery of a variable star. The period of the Moon, 29.6 days, has also been discovered in CC. We show that the actions of Seth were connected to this period, which also strongly regulated the times described as lucky for Heaven and for Earth. Now, for the first time, periodicity is discovered in the descriptions of the days in CC. Unlike many previous attempts to uncover the reasoning behind the myths of individual days, we discover the actual rules in the appearance and behaviour of deities during the whole year.

  15. Shifting Milestones of Natural Sciences: The Ancient Egyptian Discovery of Algol's Period Confirmed

    CERN Document Server

    Jetsu, Lauri

    2016-01-01

    The Ancient Egyptians wrote Calendars of Lucky and Unlucky Days that assigned astronomically influenced prognoses for each day of the year. The best preserved of these calendars is the Cairo Calendar (hereafter CC) dated to 1244--1163 B.C. We have presented evidence that the 2.85 days period in the lucky prognoses of CC is equal to that of the eclipsing binary Algol during this historical era. We wanted to find out the vocabulary that represents Algol in the mythological texts of CC. Here we show that Algol was represented as Horus and thus signified both divinity and kingship. The texts describing the actions of Horus are consistent with the course of events witnessed by any naked eye observer of Algol. These descriptions support our claim that CC is the oldest preserved historical document of the discovery of a variable star. The period of the Moon, 29.6 days, has also been discovered in CC. We show that the actions of Seth were connected to this period, which also strongly regulated the times described as ...

  16. Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period

    DEFF Research Database (Denmark)

    Capron, E.; Landais, A.; Chappellaz, J.

    2010-01-01

    Since its discovery in Greenland ice cores, the millennial scale climatic variability of the last glacial period has been increasingly documented at all latitudes with studies focusing mainly on Marine Isotopic Stage 3 (MIS 3; 28–60 thousand of years before present, hereafter ka) and characterized...... a succession of abrupt events associated with long Greenland InterStadial phases (GIS) enabling us to highlight a sub-millennial scale climatic variability depicted by (i) short-lived and abrupt warming events preceding some GIS (precursor-type events) and (ii) abrupt warming events at the end of some GIS...... (rebound-type events). The occurrence of these sub-millennial scale events is suggested to be driven by the insolation at high northern latitudes together with the internal forcing of ice sheets. Thanks to a recent NorthGRIP-EPICA Dronning Maud Land (EDML) common timescale over MIS 5, the bipolar sequence...

  17. Timing and causes of North African wet phases during the last glacial period and implications for modern human migration

    Science.gov (United States)

    Hoffmann, Dirk L.; Rogerson, Mike; Spötl, Christoph; Luetscher, Marc; Vance, Derek; Osborne, Anne H.; Fello, Nuri M.; Moseley, Gina E.

    2016-11-01

    We present the first speleothem-derived central North Africa rainfall record for the last glacial period. The record reveals three main wet periods at 65-61 ka, 52.5-50.5 ka and 37.5-33 ka that lead obliquity maxima and precession minima. We find additional minor wet episodes that are synchronous with Greenland interstadials. Our results demonstrate that sub-tropical hydrology is forced by both orbital cyclicity and North Atlantic moisture sources. The record shows that after the end of a Saharan wet phase around 70 ka ago, North Africa continued to intermittently receive substantially more rainfall than today, resulting in favourable environmental conditions for modern human expansion. The encounter and subsequent mixture of Neanderthals and modern humans – which, on genetic evidence, is considered to have occurred between 60 and 50 ka – occurred synchronously with the wet phase between 52.5 and 50.5 ka. Based on genetic evidence the dispersal of modern humans into Eurasia started less than 55 ka ago. This may have been initiated by dry conditions that prevailed in North Africa after 50.5 ka. The timing of a migration reversal of modern humans from Eurasia into North Africa is suggested to be coincident with the wet period between 37.5 and 33 ka.

  18. Late Devonian glacial deposits from the eastern United States signal an end of the mid-Paleozoic warm period

    Science.gov (United States)

    Brezinski, D.K.; Cecil, C.B.; Skema, V.W.; Stamm, R.

    2008-01-01

    A Late Devonian polymictic diamictite extends for more than 400??km from northeastern Pennsylvania across western Maryland and into east-central West Virginia. The matrix-supported, unbedded, locally sheared diamictite contains subangular to rounded clasts up to 2??m in diameter. The mostly rounded clasts are both locally derived and exotic; some exhibit striations, faceting, and polish. The diamictite commonly is overlain by laminated siltstone/mudstone facies associations (laminites). The laminites contain isolated clasts ranging in size from sand and pebbles to boulders, some of which are striated. The diamictite/laminite sequence is capped by massive, coarse-grained, pebbly sandstone that is trough cross-bedded. A stratigraphic change from red, calcic paleo-Vertisols in strata below the diamictite to non-calcic paleo-Spodosols and coal beds at and above the diamictite interval suggests that the climate became much wetter during deposition of the diamictite. The diamictite deposit is contemporaneous with regressive facies that reflect fluvial incision during the Late Devonian of the Appalachian basin. These deposits record a Late Devonian episode of climatic cooling so extreme that it produced glaciation in the Appalachian basin. Evidence for this episode of climatic cooling is preserved as the interpreted glacial deposits of diamictite, overlain by glaciolacustrine varves containing dropstones, and capped by sandstone interpreted as braided stream outwash. The Appalachian glacigenic deposits are contemporaneous with glacial deposits in South America, and suggest that Late Devonian climatic cooling was global. This period of dramatic global cooling may represent the end of the mid-Paleozoic warm interval that began in the Middle Silurian. ?? 2008 Elsevier B.V. All rights reserved.

  19. Consideration the lists of winners, as reflection of changes in the Ancient Olympic Games (in archaic and classic periods

    Directory of Open Access Journals (Sweden)

    Kasianenko O.G.

    2009-10-01

    Full Text Available The author has realized the historical analysis of one of the information sources about Ancient Olympic games, namely lists of winners. Had presented the description of geographical information, characterizing the sportsmen's place of origin, and also social origin of afore-named, allows to conduct parallels in consideration of the studied information with political and cultural changes in Greek civilization in archaic and classic periods which had a direct influence on the Olympic Games.

  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

    Humans evolved in Africa, but where in Africa and by what mechanisms remain unclear. The evolution of modern humans over the last million years is associated with the onset of major global climate fluctuations, glacial to interglacial cycles, related to the build up and melting of large ice sheets in the Northern Hemisphere. During interglacial periods, such as today, warm and wet climates favored human expansion but during cold and dry glacial periods conditions were harsh and habitats fragmented. These large climate fluctuations periodically expanded and contracted African ecosystems and led to human migrations to more hospitable glacial refugia. Periodic isolation of relatively small numbers of humans may have allowed for their rapid evolutionary divergence from the rest of Africa. During climate transitions these divergent groups may have then dispersed and interbred with other groups (hybridization). Two areas at the opposite ends of Africa stand out as regions that were periodically isolated from the rest of Africa: North Africa (the Maghreb) and the southern coastal plain (SCP) of South Africa. The Maghreb is isolated by the Sahara Desert which periodically greens and is reconnected to the rest of Africa during the transition from glacial to interglacial periods. The SCP of South Africa is isolated from the rest of Africa by the rugged mountains of the Cape Fold Belt associated with inedible vegetation and dry climates to the north. The SCP is periodically opened when sea level falls by up to 130 m during glacial maxima to expose the present day submerged inner continental shelf. A five-fold expansion of the SCP receiving more rainfall in glacial periods may have served as a refuge to humans and large migratory herds. The expansive glacial SCP habitat abruptly contracts, by as much as one-third in 300 yr, during the rapid rise in sea level associated with glacial terminations. Rapid flooding may have increased population density and competition on the SCP to

  1. Character of vegetational and environmental changes in southern Europe during the last glacial period; evidence from Lesvos Island, Greece

    Science.gov (United States)

    Margari, V.; Gibbard, P. L.; Bryant, C. L.; Tzedakis, P. C.

    2009-06-01

    This paper presents high-resolution results of palynological and sedimentological analyses undertaken on two sediment cores from the Megali Limni (ML) basin, an area characterised by serpentine soils, in the southeastern part of Lesvos Island, Greece. Six tephra horizons and multiple radiocarbon dates provide independent controls towards the development of a chronological framework. The composite pollen record spans the period from 22 to 62 thousand years ago (ka) BP and shows a number of oscillations between steppe, forest-steppe and forest, in concert with North Atlantic millennial-scale variability. Vegetation during the late Marine Isotope Stage (MIS) 4 was grassland/steppe, indicating cold and arid conditions, while sediment composition suggests increased erosion rates. Arboreal populations (dominated by Pinus and to a lesser extent deciduous Quercus) expanded during MIS 3 interstadials, suggesting increases in precipitation and temperature. Within the course of the longer interstadials, changes in vegetation composition point to a trend towards increased aridity and sometimes decreasing winter temperatures. During intervening stadials, vegetation was composed mainly of Artemisia, Chenopodiaceae and Gramineae, indicating reversals to arid and cold conditions, with most extreme conditions recorded during stadials corresponding to Heinrich Events. During the course of MIS 3, the basin was progressively infilled with sediments. Only a small portion of MIS 2 is represented in the sequence, showing a short-lived expansion of arboreal populations. Comparisons with other pollen sequences from southern Europe underscore the important role of Pinus throughout the last glacial period, a reflection of the serpentine soils of the Megali Limni area, where Pinus brutia dominates today.

  2. Ecosystem responses during Late Glacial period recorded in the sediments of Lake Łukie (East Poland)

    Science.gov (United States)

    Zawiska, Izabela; Słowiński, Michał; Correa-Metrio, Alex; Obremska, Milena; Luoto, Tomi; Nevalainen, Liisa; Woszczyk, Michał; Milecka, Krystyna

    2014-05-01

    The main objectives of this study was to reconstruct climate impact on the functioning of Lake Łukie and its catchment (Łęczna Włodawa Lake District, East European Plain) during Late Glacial period. In order to reconstruct climatic fluctuations and corresponding ecosystem responses, we analysed lake sediments for pollen, subfossil Cladocera, plant macrofossils and chemical composition of the sediment. Of these, plant macrofossils and Cladocera were used to infer minimum and mean July temperatures and ordination analysis was used to examine biotic community shifts. Multiproxy analyses of late-glacial sediments of Lake Łukie clearly show that the main driver of aquatic and terrestrial ecosystems as well as geomorphological processes in the catchment was climate variation. The history of the lake initiated during the Older Dryas. In that period, Łęczna Włodawa Lake District was covered by open habitats dominated by grasses (Poaceae), humid sites were occupied by tundra plant communities with less clubmoss (Selaginella selaginoides), dry sites by dominated by steppe-like vegetation with light-demanding species such as Helianthemum, Artemisia, Chenopodiaceae, and juniper bushes (Juniperus). Cold climate limited the growth and development of organisms in the lake, Cladocera community species composition was poor, with only few species present there all the time. During this time period, permafrost was still present in the ground limiting infiltration of rainwater and causing high erosion in the catchment area. Surface runoff is confirmed by the presence of sclerotia of Cenococcum geophilum and high terrigenous silica content. The warming of the early Allerød caused a remarkable change in the natural environment of this area. This is in accordance with the temperature rise reconstructed with the use of plant macrofossils though the Cladocera reconstruction did not recorded the rise than. This temperature increase resulted in turnover of vegetation in the

  3. Palaeoclimatic Cycles,Global Environmental Changes and New Glacial Periods Induced by the Impact of Extraterrestrial Bodies

    Institute of Scientific and Technical Information of China (English)

    王世杰; 欧阳自远; 等

    1999-01-01

    In terms of Earth-Sun geometry,the Milankovitch theory has successfully explained most of the cyclie palaeoclimatic variations during the history of the Earth,especially in the Quaternary.In this paper,the authors suggest that the impact of extraterrestrial bodies on the Earth may be another mechanism to cause palaeoclimatic cycles,global environmental changes and new glacial periods,Based on geological and geochemical records in the boundary layers produced by six huge Cenozoic bolide-impact events(65,34,15,2.4,1.1,0.73Ma B.P.),including those at 34,15,1.1and 0.73MaB.P.which are represented by four famous tektite-strewn fields,the process and mechanics of palaeoclimatic cycles and global environmental eatastrophes induced by extraterrestrial impact are discussed in detail.Impact-generated dust.soot and aerosol floating in the staratosphere could result in short-term(<1year),rapid drop in tempeature immediately after impact.Through self-regulation of the Earth's climate system,the temperature at the surface slowly went up within 100a and maintained stable for a long time at 250K.If there were no other factors leading to the break-down of the nely-established equilibrium,a new glaciel peood would be initiated.Estimating from the thickess of δ13C and δ18O anomalies in sediments across the impact boundary layer and deposition rate,the duration of two stages of the palaeoclimate cycle in the form of cold weather-greenhouse effect-normal weather war 104-105a ,respectively.The conclusion deduced from the above model is supported by palaeotemperature change recorded by oxygen isotope in sediments across the impact boundary layer.

  4. Vigorous exchange between the Indian and Atlantic oceans at the end of the past five glacial periods.

    Science.gov (United States)

    Peeters, Frank J C; Acheson, Ruth; Brummer, Geert-Jan A; De Ruijter, Wilhelmus P M; Schneider, Ralph R; Ganssen, Gerald M; Ufkes, Els; Kroon, Dick

    2004-08-05

    The magnitude of heat and salt transfer between the Indian and Atlantic oceans through 'Agulhas leakage' is considered important for balancing the global thermohaline circulation. Increases or reductions of this leakage lead to strengthening or weakening of the Atlantic meridional overturning and associated variation of North Atlantic Deep Water formation. Here we show that modern Agulhas waters, which migrate into the south Atlantic Ocean in the form of an Agulhas ring, contain a characteristic assemblage of planktic foraminifera. We use this assemblage as a modern analogue to investigate the Agulhas leakage history over the past 550,000 years from a sediment record in the Cape basin. Our reconstruction indicates that Indian-Atlantic water exchange was highly variable: enhanced during present and past interglacials and largely reduced during glacial intervals. Coherent variability of Agulhas leakage with northern summer insolation suggests a teleconnection to the monsoon system. The onset of increased Agulhas leakage during late glacial conditions took place when glacial ice volume was maximal, suggesting a crucial role for Agulhas leakage in glacial terminations, timing of interhemispheric climate change and the resulting resumption of the Atlantic meridional overturning circulation.

  5. South Atlantic intermediate water advances into the North-east Atlantic with reduced Atlantic meridional overturning circulation during the last glacial period

    Science.gov (United States)

    Dubois-Dauphin, Quentin; Bonneau, Lucile; Colin, Christophe; Montero-Serrano, Jean-Carlos; Montagna, Paolo; Blamart, Dominique; Hebbeln, Dierk; Van Rooij, David; Pons-Branchu, Edwige; Hemsing, Freya; Wefing, Anne-Marie; Frank, Norbert

    2016-06-01

    The Nd isotopic composition (ɛNd) of seawater and cold-water coral (CWC) samples from the Gulf of Cádiz and the Alboran Sea, at a depth of 280-827 m were investigated in order to constrain middepth water mass dynamics within the Gulf of Cádiz over the past 40 ka. ɛNd of glacial and Holocene CWC from the Alboran Sea and the northern Gulf of Cádiz reveals relatively constant values (-8.6 to -9.0 and -9.5 to -10.4, respectively). Such values are similar to those of the surrounding present-day middepth waters from the Mediterranean Outflow Water (MOW; ɛNd ˜ -9.4) and Mediterranean Sea Water (MSW; ɛNd ˜ -9.9). In contrast, glacial ɛNd values for CWC collected at thermocline depth (550-827 m) in the southern Gulf of Cádiz display a higher average value (-8.9 ± 0.4) compared to the present-day value (-11.7 ± 0.3). This implies a higher relative contribution of water masses of Mediterranean (MSW) or South Atlantic origin (East Antarctic Intermediate Water, EAAIW). Our study has produced the first evidence of significant radiogenic ɛNd values (˜ -8) at 19, 23-24, and 27 ka, which are coeval with increasing iceberg discharges and a weakening of Atlantic Meridional Overturning Circulation (AMOC). Since MOW ɛNd values remained stable during the last glacial period, it is suggested that these radiogenic ɛNd values most likely reflect an enhanced northward propagation of glacial EAAIW into the eastern Atlantic Basin.

  6. A stratigraphic framework for naming and robust correlation of abrupt climatic changes during the last glacial period based on three synchronized Greenland ice core records

    Science.gov (United States)

    Rasmussen, Sune O.

    2014-05-01

    Due to their outstanding resolution and well-constrained chronologies, Greenland ice core records have long been used as a master record of past climatic changes during the last interglacial-glacial cycle in the North Atlantic region. As part of the INTIMATE (INtegration of Ice-core, MArine and TErrestrial records) project, protocols have been proposed to ensure consistent and robust correlation between different records of past climate. 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. This is based on a combination of isotope ratios (δ18O, reflecting mainly local temperature) and calcium concentrations (reflecting mainly atmospheric dust loading). 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. This is a key step aimed at promoting unambiguous comparison and correlation between different proxy records, as well as a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations. The work presented is under review for publication in Quaternary Science Reviews. Author team: S

  7. High-resolution climate records from two stalagmites in Qixin Cave, southern Guizhou, and Heinrich events during the last glacial period

    Institute of Scientific and Technical Information of China (English)

    ZhangMeiliang; ChengHai; YuanDaoxian; LinYushi; QinJiaming; WangHuat; FengYumei; TuLingling; ZhangHuiling

    2004-01-01

    The time sequence of high-resolution paleoclimatic changes since the last glacial period--60,500 yr B.P.--has been reconstructed with high-precision TIMS-U series dates and analyses of the oxygen isotopes from Q4 and Q6 stalagmites of the Qixin Cave in southern Guizhou. Comparative analyses of δ18O curves from the GISP2' ice core and the two stalagmites shows that the depositional records of the Dansgaard-Oeschger cycle events 1-18 and Heinrich's events H1-H5 from the records of the two stalagmites reflect rapid climate changes over a short time scale since the last glacial stage, and indicates the precise boundary lines at which the cold events occurred. The study results have shown that the records of the cold and warm events from the two stalagmites since 60,500 yr B.P. are the reflection of the paleo-monsoon circulation. Changes are clearly affected by the climate oscillation of the North Atlantic Ocean, and indicate that they have a strong teleconnection with the paleoclimate changes that occurred in the North Polar region. The records of δ18O from the Q4 and Q6 stalagmites indicate that the δ18O values from 60,590 yr B.P. to 11,290 yr B.P. changed from a more negative (or lighter)drift to a heavier or positive drift trend in the last glacial period. The data reflect the weakening of the Asian summer monsoon and the climate which generally became drier and cooler.

  8. Different climatic controls of soil δ13Corg in three mid-latitude regions of the Northern Hemisphere since the Last Glacial period

    Institute of Scientific and Technical Information of China (English)

    RAO ZhiGuo; ZHU ZhaoYu; ZHANG JiaWu

    2007-01-01

    Paleoecological records of soil δ13Corg from three regions in the middle latitudes of the Northern Hemisphere, including the Chinese Loess Plateau (CLP), the Great Plains and adjacent areas of North America and northwestern Europe, showed different variations since the Last Glacial period. An attempt was made to evaluate the causes for the difference in δ13Corg on the basis of the modern climatic data collected in these regions and of the modern C3 and C4 plant distributions. The analysis indicates that temperature, especially the growing season temperature, has a dominant control on the growth of C4 plants. When the mean annual or growing season temperatures are below the "threshold value", the growth of C4 plants is limited. When the temperature is above the "threshold value", C4 plants can grow under a wide range of precipitation. However, when the precipitation is high enough to favor the growth of trees, the proportions of C4 plants in local biomass will decline. The implicit control factor recovered by sedimentary records is consistent with the control factor on modern C3/C4 distribution. Pure C3 plants have been dominating the local biomass since the Last Glacial period in European loess region, mainly owing to the low local temperature. The increases in C4 plants from the late Pleistocene to the Holocene in the Chinese Loess Plateau, the Great Plains and adjacent areas, mainly reflect the influence of increasing temperature.

  9. INAA OF SOME ANCIENT COINS FROM POST GUPTA PERIOD AND MUGHAL SALTANAT

    Institute of Scientific and Technical Information of China (English)

    NilimaSRajurkar; AKJha; 等

    1994-01-01

    Non-destructive analysis of some electrum coins from post Gupta period and of coins from different mints of Mughal emperors,Shahjahan and Aurangzed.have been done by instrumental neutron activation analysis(INAA) using 252Cf neutron source.The elemental content of these coins are determined by comparator method by mneasuring the activities of the radioisotopes formed after(n,γ) reactions,at their corresponding photopeaks.It is found that identified electrum coins contain copper as a major component and hence can be termed as cupro-electrum coins.As regards the analysis of coins from different mints there is no much variation in silver content while copper content varies from mint to mint.Coins from both the emperore are found to contain considerable amount of gold.

  10. Sea Level Changes And Depositional Environments In The Izmit Gulf, Eastern Marmara Sea, During The Late Glacial-Holocene Period

    Science.gov (United States)

    Cagatay, M. N.; Görür, N.; Polonia, A.; Demirbag, E.; Sakinc, M.; Cormier, M. H.; Capotondi, L.; McHugh, C.; Emre, O.; Eris, K.

    2003-04-01

    Offshore and onshore stratigraphic studies, together with high-resolution shallow seismic reflection profiling and multibeam bathymetric mapping, were carried out in the western and central part of the Izmit Gulf. These studies indicate that the western Gulf Izmit was a fresh water environment as part of the Marmara "lake" during the late glaciation and early deglaciation until ~12 kyr BP, when the Marmara basin was inundated by the Mediterranean waters. Correlation of 14C-dated onshore and offshore stratigraphic units in the western Izmit Gulf indicates that generally coarse late glacial sediments overlie a marked erosion surface formed during the low water level of the Marmara "Lake". These coarse sediments are followed upwards by 10.4-7 kyr BP old transgressive and the late Holocene post-transgression mud units. The bathymetry and subbottom chirp profiles clearly show that the palaeoshoreline of this lake was located at -85 m, having been controlled by the bedrock sill depth of the Çanakkale Strait. Another palaeoshoreline observed -65 m on northern margin of the Western Izmit and Karamürsel basins was probably formed during the Younger Dryas sea-level still stand. The shelf areas during about this time were colonized by bioherms, which were drowned and disappeared after further rise of the sea level. The presence of a -65 m marine paleoshoreline in the Karamürsel basin indicate that the sill restricting this basin to the west was much deeper than its present -55 m level and placed further south. The Gölcük basin restricted by a -38 m sill to its west was not probably flooded by the marine waters until ~10 kyr BP. Onshore alluvial fan deposits include a 10-15 cm. thick layer at 18 m containing a mixture of bones, charcoal, marine shells and brick tiles. This layer, dated at 2875 +-85 yr BP (1049 +-82 BC), is believed to be a possible tsunami deposit.

  11. Medicines in ancient period

    Digital Repository Service at National Institute of Oceanography (India)

    Netravalkar, M.G.S.

    stream_size 7 stream_content_type text/plain stream_name New_Trend_Indian_Art_Archaeol_1992_387.pdf.txt stream_source_info New_Trend_Indian_Art_Archaeol_1992_387.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  12. Maternal and paternal genetic diversity of ancient sheep in Estonia from the Late Bronze Age to the post-medieval period and comparison with other regions in Eurasia.

    Science.gov (United States)

    Rannamäe, E; Lõugas, L; Niemi, M; Kantanen, J; Maldre, L; Kadõrova, N; Saarma, U

    2016-04-01

    Sheep were among the first domesticated animals to appear in Estonia in the late Neolithic and became one of the most widespread livestock species in the region from the Late Bronze Age onwards. However, the origin and historical expansion of local sheep populations in Estonia remain poorly understood. Here, we analysed fragments of the hypervariable D-loop of mitochondrial DNA (mtDNA; 213 bp) and the Y-chromosome SRY gene (130 bp) extracted from 31 archaeological sheep bones dated from approximately 800 BC to 1700 AD. The ancient DNA data of sheep from Estonia were compared with ancient sheep from Finland as well as a set of contemporary sheep breeds from across Eurasia in order to place them in a wider phylogeographical context. The analysis shows that: (i) 24 successfully amplified and analysed mtDNA sequences of ancient sheep cluster into two haplogroups, A and B, of which B is predominant; (ii) four of the ancient mtDNA haplotypes are novel; (iii) higher mtDNA haplotype diversity occurred during the Middle Ages as compared to other periods, a fact concordant with the historical context of expanding international trade during the Middle Ages; (iv) the proportion of rarer haplotypes declined during the expansion of sheep from the Near Eastern domestication centre to the northern European region; (v) three male samples showed the presence of the characteristic northern European haplotype, SNP G-oY1 of the Y-chromosome, and represent the earliest occurrence of this haplotype. Our results provide the first insight into the genetic diversity and phylogeographical background of ancient sheep in Estonia and provide basis for further studies on the temporal fluctuations of ancient sheep populations.

  13. Sediment core fossils in ancient Lake Ohrid: testing for faunal change in molluscs since the Last Interglacial period

    Directory of Open Access Journals (Sweden)

    C. Albrecht

    2010-05-01

    Full Text Available Ancient Lake Ohrid is probably of early Pleistocene or Pliocene origin and amongst the few lakes in the world harboring an outstanding degree of endemic biodiversity. Although there is a long history of evolutionary research in Lake Ohrid, particularly on molluscs, a mollusc fossil record has been missing up to date.

    For the first time, gastropod and bivalve fossils are reported from the basal, calcareous part of a 2.6 m long sediment succession (core Co1200 from the north-eastern part of Lake Ohrid. Electron spin resonance (ESR dating of mollusc shells from the same stratigraphic level yielded an age of 130±28 ka. Lithofacies III sediments, i.e. a subdivision of the stratigraphic unit comprising the basal succession of core Co1200 between 181.5–263 cm appeared solid, grayish-white, and consisted almost entirely of silt-sized endogenic calcite (CaCO3>70% and intact and broken mollusc shells. Here we compare the faunal composition of the thanatocoenosis with recent mollusc associations in Lake Ohrid. A total of 13 mollusc species (9 gastropod and 4 bivalve species could be identified within Lithofacies III sediments. The value of sediment core fossils for reconstructing palaeoenvironmental settings was evaluated. The agreement between sediment and palaeontological proxies was tested. The combined findings of the ecological study and the sediment characteristics suggest deposition in a shallow water environment during the Last Interglacial period.

    We tested for major faunal changes since the Last Interglacial period and searched for signs of extinction events. The fossil fauna exclusively included species also found in the present fauna, i.e. no extinction events are evident for this site since the Last Interglacial. The thanatocoenosis showed the highest similarity with recent Intermediate Layer (5–25 m mollusc assemblages. The demonstrated existence of a mollusc fossil record in Lake Ohrid sediment cores also

  14. 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...

  15. Indian monsoon variations during three contrasting climatic periods: the Holocene, Heinrich Stadial 2 and the last interglacial-glacial transition

    Science.gov (United States)

    Zorzi, Coralie; Fernanda Sanchez Goñi, Maria; Anupama, Krishnamurthy; Prasad, Srinivasan; Hanquiez, Vincent; Johnson, Joel; Giosan, Liviu

    2016-04-01

    In contrast to the East Asian and African monsoons the Indian monsoon is still poorly documented throughout the last climatic cycle (last 135,000 years). Pollen analysis from two marine sediment cores (NGHP-01-16A and NGHP-01-19B) collected from the offshore Godavari and Mahanadi basins, both located in the Core Monsoon Zone (CMZ) reveals changes in Indian summer monsoon variability and intensity during three contrasting climatic periods: the Holocene, the Heinrich Stadial (HS) 2 and the Marine Isotopic Stage (MIS) 5/4 during the ice sheet growth transition. During the first part of the Holocene between 11,300 and 4,200 cal years BP, characterized by high insolation (minimum precession, maximum obliquity), the maximum extension of the coastal forest and mangrove reflects high monsoon rainfall. This climatic regime contrasts with that of the second phase of the Holocene, from 4,200 cal years BP to the present, marked by the development of drier vegetation in a context of low insolation (maximum precession, minimum obliquity). The historical period in India is characterized by an alternation of strong and weak monsoon centennial phases that may reflect the Medieval Climate Anomaly and the Little Ice Age, respectively. During the HS 2, a period of low insolation and extensive iceberg discharge in the North Atlantic Ocean, vegetation was dominated by grassland and dry flora indicating pronounced aridity as the result of a weak Indian summer monsoon. The MIS 5/4 glaciation, also associated with low insolation but moderate freshwater fluxes, was characterized by a weaker reduction of the Indian summer monsoon and a decrease of seasonal contrast as recorded by the expansion of dry vegetation and the development of Artemisia, respectively. Our results support model predictions suggesting that insolation changes control the long term trend of the Indian monsoon precipitation, but its millennial scale variability and intensity are instead modulated by atmospheric

  16. Glacial cycles

    DEFF Research Database (Denmark)

    Kaufmann, R. K.; Juselius, Katarina

    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...

  17. The period from the Last Interglacial to the Last Glacial Maximum (MIS 5 - 2) in different archives of southern Italy

    Science.gov (United States)

    Sauer, Daniela; Wagner, Stephen; Al-Sharif, Riyad; Brückner, Helmut; Scarciglia, Fabio; Mastronuzzi, Giuseppe; Stahr, Karl

    2010-05-01

    Sediment cores from S Italy provide excellent archives of Late Pleistocene climate and vegetation changes, particularly from the Lago Grande di Monticchio (Allen et al., 2000; Brauer et al., 2007), the crater lakes of the central West coast of Italy, Valle di Castiglione, Lagaccione, Lago di Vico, Stracciacappa (Follieri et al., 1998) and the marine core GNS84-C106 in the Gulf of Salerno (Di Donato et al., 2008). These records show that woody Mediterranean vegetation covered the region during most of the Last Interglacial (from 129-127 ka BP until 115-116 ka BP). In the last phase of the interglacial (from 115-116 ka BP until about 110 ka BP), the forest composition changed, showing an increase in Abies and Alnus and a decrease in Mediterranean taxa. The interglacial was terminated by the Melisey I Stadial, during which grasses and Betula predominated. Forests spread again during St. Germain I, but they consisted mainly of Fagus, Abies and various deciduous trees. A steppe phase (Melisey II) followed, in which Chenopodiaceae prevailed, before St. Germain II set in, with forests dominated by Abies, Ulmus and Carpinus. From the end of St. Germain II until the Lateglacial, steppe, composed of Artemisia, Gramineae and Chenopodiaceae, predominated, with week expansions of trees (mainly Pinus and Juniperus) during several periods. What information can be obtained from terrestrial geo-archives for the same region and time? Sea level highstands, corresponding to interglacial and interstadial periods, created marine terraces along the coasts of S Italy. We are currently carrying out a geomorphological, sedimentological and pedological study on a flight of 11 uplifted marine terraces in the central Gulf of Taranto, the lowermost of them falling into the time span of interest. The terraces generally comprise a gravel body, deposited in a littoral environment, covered by a layer of fine sediments of varying thickness. The latter were deposited when the terrace was still close

  18. Evidence of reworking and resuspension of carbonates during last glacial maximum and early deglacial period along the southwest coast of India

    Indian Academy of Sciences (India)

    Kamlesh Verma; M Sudhakar

    2006-12-01

    A gravity core collected from the upper slope of southwest of Quilon at a water depth of 776m (Lat: 8° 12′ 263′′N, Long: 76° 28′ 281′′E) was analysed for texture (carbonate free), calcium carbonate and organic carbon. Variation in silicic fraction seems to be controlled by silt, i.e., enrichment from 15 ka BP to 10 ka BP and then constant in Holocene. Below 15 ka BP, the silicic fraction gets depleted compared to the Holocene section with a minimum around 21 ka BP. Clay content remains nearly constant except in the Holocene where it shows an enrichment. Carbonate content of less than 63 micron when computed by subtracting coarse fraction content from the total carbonate suggests that the total carbonates are mainly concentrated in the finer fraction. All these carbonate phases show an inverse relationship with silicic fraction except in Holocene. Below 15 ka BP, CaCO3 dominates in sediments comprising more than 65%, such an increase is also seen in the coarse fraction. Coarse fraction from these sections contains abundant nodular type aggregates encrusting small forams. This period is marked by a high sedimentation rate comparable to Holocene. These parameters suggest that the productivity and precipitation have increased in the Holocene due to the intensification of the southwest monsoon. During the last glacial maximum and early deglacial period the high sedimentation rate indicates redeposition of the carbonates from the existing carbonate lithofacies situated between Quilon and Cape Comorin probably due to the slope instability.

  19. Ancient DNA

    DEFF Research Database (Denmark)

    Willerslev, Eske; Cooper, Alan

    2004-01-01

    ancient DNA, palaeontology, palaeoecology, archaeology, population genetics, DNA damage and repair......ancient DNA, palaeontology, palaeoecology, archaeology, population genetics, DNA damage and repair...

  20. PALEOCLIMATE: Glacial Climate Instability.

    Science.gov (United States)

    Labeyrie, L

    2000-12-08

    Throughout the last glacial period, rapid climatic changes called Dansgaard-Oeschger (D-O) events occurred in the Northern Hemisphere. As Labeyrie discusses in his Perspective, these events are ideal targets for testing our understanding of climate change and developing climatic change models. Important steps toward understanding D-O events, particularly regarding the role of the low latitudes, are now reported by Hughen et al. and Peterson et al.

  1. Review of the studies on climate change since the last inter-glacial period on the Tibetan Plateau%青藏高原不同时段气候变化的研究综述

    Institute of Scientific and Technical Information of China (English)

    李潮流; 康世昌

    2006-01-01

    As the "Third Pole" of the world, the Tibetan Plateau has important effects on climate of its surrounding areas and even the whole world. Many results have been achieved on climate change since the last inter-glacial period in recent decades from ice core, tree-ring and lake sediment records over the Tibetan Plateau. In this paper, we review these achievements, especially those in the special periods.During the last inter-glacial period, temperature went down rapidly and went up slowly. The temperature record of the last glacial period is consistent with Greenland ice core records, also having own features over the Tibetan Plateau. Younger Dryas event agrees with the records from Europe and Greenland.Generally speaking, it is warm in the Holocene, and temperature has been rising gradually in the last 2000 years and gone up rapidly in recent decades. Climate changes on different time scales on the Tibetan Plateau occurred earlier and the change amplitude is larger than those in other parts of China.

  2. Periodic jökulhlaups from Pleistocene glacial Lake Missoula-New evidence from varved sediment in northern Idaho and Washington

    Science.gov (United States)

    Waitt, Richard B.

    1984-01-01

    Newly examined exposures in northern Idaho and Washington show that catastrophic floods from glacial Lake Missoula during late Wisconsin time were repeated, brief jökulhlaups separated by decades of quiet glaciolacustrine and subaerial conditions. Glacial Priest Lake, dammed in the Priest River valley by a tongue of the Purcell trench lobe of the Cordilleran ice sheet, generally accumulated varved mud; the varved mud is sharply interrupted by 14 sand beds deposited by upvalley-running currents. The sand beds are texturally and structurally similar to slackwater sediment in valleys in southern Washington that were backflooded by outbursts from glacial Lake Missoula. Beds of varved mud also accumulated in glacial Lake Spokane (or Columbia?) in Latah Creek valley and elsewhere in northeastern Washington; the mud beds were disrupted, in places violently, during emplacement of each of 16 or more thick flood-gravel beds. This history corroborates evidence from southern Washington that only one graded bed is deposited per flood, refuting a conventional idea that many beds accumulated per flood. The total number of such floodlaid beds in stratigraphic succession near Spokane is at least 28. The mud beds between most of the floodlaid beds in these valleys each consist of between 20 and 55 silt-to-clay varves. Lacustrine environments in northern Idaho and Washington therefore persisted for two to six decades between regularly recurring, colossal floods from glacial Lake Missoula.

  3. Ancient Egypt

    Science.gov (United States)

    Swamy, Ashwin Balegar

    This thesis involves development of an interactive GIS (Geographic Information System) based application, which gives information about the ancient history of Egypt. The astonishing architecture, the strange burial rituals and their civilization were some of the intriguing questions that motivated me towards developing this application. The application is a historical timeline starting from 3100 BC, leading up to 664 BC, focusing on the evolution of the Egyptian dynasties. The tool holds information regarding some of the famous monuments which were constructed during that era and also about the civilizations that co-existed. It also provides details about the religions followed by their kings. It also includes the languages spoken during those periods. The tool is developed using JAVA, a programing language and MOJO (Map Objects Java Objects) a product of ESRI (Environmental Science Research Institute) to create map objects, to provide geographic information. JAVA Swing is used for designing the user interface. HTML (Hyper Text Markup Language) pages are created to provide the user with more information related to the historic period. CSS (Cascade Style Sheets) and JAVA Scripts are used with HTML5 to achieve creative display of content. The tool is kept simple and easy for the user to interact with. The tool also includes pictures and videos for the user to get a feel of the historic period. The application is built to motivate people to know more about one of the prominent and ancient civilization of the Mediterranean world.

  4. The Impacts of Glacial Recession on Riverine Nutrient Fluxes and the Age and Bioavailability of Riverine DOM in Gulf of Alaska Watersheds

    Science.gov (United States)

    Hood, E.; Fellman, J.; Spencer, R.; Scott, D.

    2009-05-01

    Watersheds draining into the Gulf of Alaska (GOA) contain 75,300 km2 of glacier ice and are experiencing some of the highest rates of glacial erosion on earth, with thinning rates exceeding 5 meters of water equivalent at low elevations. This ongoing loss of glacial ice is rapidly altering landcover in GOA watersheds and has important implications for the physical and biogeochemical properties of rivers as well as the delivery of freshwater and nutrients to near-shore marine ecosystems along the GOA. We are studying the effects of changing glacial coverage on watershed biogeochemistry in eleven coastal watersheds along the GOA that vary markedly in watershed glacial coverage (range = 0-64%, mean = 36%). Our results indicate that decreased glacial coverage is strongly correlated with the temperature (r2=0.92, p<0.01) and turbidity (r2=0.87, p<0.01) of streamwater during the summer runoff season. In addition, flux modeling from three of the rivers with continuous gages suggests that riverine yields of dissolved organic carbon (DOC) and dissolved inorganic nitrogen (DIN) will increase with decreasing glacial coverage. In contrast, riverine fluxes of dissolved organic nitrogen (DON) appear to be decoupled from DOC fluxes and do not change with glacial coverage, while yields of soluble reactive phosphorus decrease with glacial coverage. Characterization of riverine dissolved organic matter (DOM) from our study watersheds using spectroscopic and isotopic analyses (13C and 14C) has shown that DOM is older and relatively rich in protein in watersheds with high glacial coverage. Moreover, the 14C age of DOM from these heavily glaciated watersheds exceeds 3500 years. Together these findings are consistent with the idea that glacial DOM is derived in large part from sub- and pro- glacial microbial populations that are supported by ancient carbon buried during the re-advance of glaciers along the GOA after the hypsothermal warm period ( ˜3,000-5,000 yrs bp). Interestingly

  5. Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period

    Science.gov (United States)

    Kobayashi, Daisuke; Yamamoto, Masanobu; Irino, Tomohisa; Nam, Seung-Il; Park, Yu-Hyeon; Harada, Naomi; Nagashima, Kana; Chikita, Kazuhisa; Saitoh, Sei-Ichi

    2016-12-01

    This paper describes the distribution of detrital minerals and sediment color in the surface sediments of the western Arctic Ocean and the northern Bering Sea and investigates the relationship between mineral composition and sediment provenance. This relationship was used to determine the provenance of western Arctic Ocean sediments deposited during the last glacial period. Sediment color is governed by water depth, diagenesis, and mineral composition. An a*-b* diagram was used to trace color change during diagenesis in the Arctic Ocean sediments. The mineral composition of surface sediments is governed by grain size and provenance. The feldspar/quartz ratio of the sediments studied was higher on the Siberian side than on the North American side of the western Arctic Ocean. The (chlorite + kaolinite)/illite and chlorite/illite ratios were high in the Bering Sea but decrease northwards in the Chukchi Sea. Thus, these ratios are useful for provenance studies in the Chukchi Sea area as indices of the Beaufort Gyre circulation and the Bering Strait inflow. The sediments deposited during the last glacial period have a lower feldspar/quartz ratio and a higher dolomite intensity than Holocene sediments on the Chukchi Plateau, suggesting a greater contribution of North American grains during the last glacial period.

  6. Influences of glacial melt and permafrost thaw on the age of dissolved organic carbon in the Yukon River basin

    Science.gov (United States)

    Aiken, George R.; Spencer, Robert G.M.; Striegl, Rob; Schuster, Paul F.; Raymond, Peter A.

    2016-01-01

    Responses of near-surface permafrost and glacial ice to climate change are of particular significance for understanding long-term effects on global carbon cycling and carbon export by high-latitude northern rivers. Here we report Δ14C-dissolved organic carbon (DOC) values and dissolved organic matter optical data for the Yukon River, 15 tributaries of the Yukon River, glacial meltwater, and groundwater and soil water end-member sources draining to the Yukon River, with the goal of assessing mobilization of aged DOC within the watershed. Ancient DOC was associated with glacial meltwater and groundwater sources. In contrast, DOC from watersheds dominated by peat soils and underlain by permafrost was typically enriched in Δ14C indicating that degradation of ancient carbon stores is currently not occurring at large enough scales to quantitatively influence bulk DOC exports from those landscapes. On an annual basis, DOC exported was predominantly modern during the spring period throughout the Yukon River basin and became older through summer-fall and winter periods, suggesting that contributions of older DOC from soils, glacial meltwaters, and groundwater are significant during these months. Our data indicate that rapidly receding glaciers and increasing groundwater inputs will likely result in greater contributions of older DOC in the Yukon River and its tributaries in coming decades.

  7. Glacial atmospheric phosphorus deposition

    Science.gov (United States)

    Kjær, Helle Astrid; Dallmayr, Remi; Gabrieli, Jacopo; Goto-Azuma, Kumiko; Hirabayashi, Motohiro; Svensson, Anders; Vallelonga, Paul

    2016-04-01

    Phosphorus in the atmosphere is poorly studied and thus not much is known about atmospheric phosphorus and phosphate transport and deposition changes over time, though it is well known that phosphorus can be a source of long-range nutrient transport, e.g. Saharan dust transported to the tropical forests of Brazil. In glacial times it has been speculated that transport of phosphorus from exposed shelves would increase the ocean productivity by wash out. However whether the exposed shelf would also increase the atmospheric load to more remote places has not been investigated. Polar ice cores offer a unique opportunity to study the atmospheric transport of aerosols on various timescales, from glacial-interglacial periods to recent anthropogenic influences. We have for the first time determined the atmospheric transport of phosphorus to the Arctic by means of ice core analysis. Both total and dissolved reactive phosphorus were measured to investigate current and past atmospheric transport of phosphorus to the Arctic. Results show that glacial cold stadials had increased atmospheric total phosphorus mass loads of 70 times higher than in the past century, while DRP was only increased by a factor of 14. In the recent period we find evidence of a phosphorus increase over the past 50 yrs in ice cores close to human occupation likely correlated to forest fires. References: Kjær, Helle Astrid, et al. "Continuous flow analysis method for determination of dissolved reactive phosphorus in ice cores." Environmental science & technology 47.21 (2013): 12325-12332. Kjær, Helle Astrid, et al. "Greenland ice cores constrain glacial atmospheric fluxes of phosphorus." Journal of Geophysical Research: Atmospheres120.20 (2015).

  8. The Prevalence of Vitamin D Deficiency in Ancient Egyptian Population from Baharia Oasis, the Greco Roman Period

    Directory of Open Access Journals (Sweden)

    Rokia Abd ElShafy Soliman El-Banna*, , Azza Mohamed Sarry El-Din*, Fatma Ahmed Eid**, Walaa Yousef Mohamed Ali

    2014-04-01

    Full Text Available Background: Vitamin D deficiency is considered to be the most common nutritional deficiency and also one of the most common undiagnosed medical conditions in the world. Vitamin D is naturally present only in minor amounts in most foods; the great majority is synthesized by the action of ultraviolet light on chemical precursors in the skin. The manifestation of vitamin D deficiency in sub adults is referred to as rickets, and in adults, osteomalacia . Rickets and osteomalacia are the sub adult and adult expressions of a disease in which the underlying problem is a failure to mineralize bone protein (osteoid. The most common cause of this disease is a physiological deficiency in vitamin D. The associated problems include deformed bones. Material and Methods: This study aimed to investigate the skeletal remains of ancient Egyptians from Baharia Oasis population for lesions indicative of vitamin D deficiency (rickets and osteomalacia. The material consisted of 1075 commingled bones (38 sub adults and1037 adults. They were recovered from Baharia oasis. Results: The results showed that, there was no evidence of rickets in sub adult group. The prevalence of osteomalacia in adult Baharia populations was 7.4% ; all were adult males. This result could indicate that this population was subjected to sunlight all over the year and their diet was rich of calcium and phosphorus. Conclusion: These few cases that were found may be due to mechanical stress during wine and textile production.

  9. Groundwater flow modeling of periods with periglacial and glacial climate conditions for the safety assessment of the proposed high-level nuclear waste repository site at Forsmark, Sweden

    Science.gov (United States)

    Vidstrand, Patrik; Follin, Sven; Selroos, Jan-Olof; Näslund, Jens-Ove

    2014-09-01

    The impact of periglacial and glacial climate conditions on groundwater flow in fractured crystalline rock is studied by means of groundwater flow modeling of the Forsmark site, which was recently proposed as a repository site for the disposal of spent high-level nuclear fuel in Sweden. The employed model uses a thermal-hydraulically coupled approach for permafrost modeling and discusses changes in groundwater flow implied by the climate conditions found over northern Europe at different times during the last glacial cycle (Weichselian glaciation). It is concluded that discharge of particles released at repository depth occurs very close to the ice-sheet margin in the absence of permafrost. If permafrost is included, the greater part discharges into taliks in the periglacial area. During a glacial cycle, hydraulic gradients at repository depth reach their maximum values when the ice-sheet margin passes over the site; at this time, also, the interface between fresh and saline waters is distorted the most. The combined effect of advances and retreats during several glaciations has not been studied in the present work; however, the results indicate that hydrochemical conditions at depth in the groundwater flow model are almost restored after a single event of ice-sheet advance and retreat.

  10. [The campaign of returning to the ancient in sphygmology in the Republican Period as viewed from Mai xue cong shu (Series of Pulse Taking)].

    Science.gov (United States)

    Han, Sujie; Hu, Xiaofeng

    2015-01-01

    From the Southern and Northern Dynasties to the beginning of the Northern Song Dynasty, the models of "master and apprentice" and "physician of long family tradition for generations" were the main ways for teaching medical knowledge. With the rapid amassment of medical books in the Due to the rapid transmission of western science and technology into China in the Republican period, the art of pulse taking had been treated as unscientific. Yao Xinyuan advocated the recovery of ancient pulse taking of the three-portion approach, i.e., taking the pulses at the neck, hands, and feet for comparison. To spread this idea, Yao and Zhang Ziying compiled the Mai xue cong shu (Series of Pulse Taking) in 1937-1947. Altogether 4 issues were published carrying 29 articles concerning the theoretical exploration, experimental research, and clinical practice. Their thinking and approaches were influential to the study and development of modern sphygmology.

  11. Long-period seismic response of ancient timber buildings%古建筑木构架长周期地震响应分析

    Institute of Scientific and Technical Information of China (English)

    张风亮; 赵鸿铁; 薛建阳; 隋龑

    2012-01-01

    In present research fields of ancient building, the seismic analysis of a timber structure is most under common earthquake, but studies on dynamic response of a timber structure under long-period earthquake are relatively few. Here, two typical long-period seismic waves and two common seismic ones were chosen, and the dynamic respones of the whole structure of an ancient timber building under the two types of waves were studied. Results showed that Chi-Chi and Loma-Prieta waves have much more components of leng period than El-Centro and LAN Zhou waves do; the two long-period seismic waves have far less higher frequency components than the two common seismic waves do; under light earthquake, the dynamic response of the structure to long-period and common seismic waves is probably the same, while under the moderate and heavy earthquakes, the dynamic response of the structure to long-period seismic waves is much larger than that to common seismic waves; the anti-vibration effect of the semi-rigid connection building Sun-Mao under heavy earthquake (400gal) is better than that under moderate (220gal)and light earthquakes (110gal).%在目前古建筑研究领域中,对木构架的抗震分析绝大多数都是在普通地震动作用下,而对长周期地震动作用下的木构架动力研究相对较少.主要选择了两条典型的长周期地震波和两条普通的地震波,对古建筑木构架整体结构在两类地震波作用下的动力响应进行比较研究.研究表明,台湾集集地震波和Loma-Prieta地震波的长周期成分要比E1 - Centro地震波和兰州波的长周期成分丰富的多;两条长周期地震波的高频成分远远少于两条普通地震波;在小震时,古建筑木构架对长周期地震动的动力响应值与普通地震动相差不大,而在中震和大震时,对长周期地震动的动力响应值要远远高于普通地震动;大震(400 gal)时木构架的减震效果比中震(220 gal)、小震(110 gal)时的减震效果要好.

  12. Ancient Egypt.

    Science.gov (United States)

    Evers, Virginia

    This four-week fourth grade social studies unit dealing with religious dimensions in ancient Egyptian culture was developed by the Public Education Religion Studies Center at Wright State University. It seeks to help students understand ancient Egypt by looking at the people, the culture, and the people's world view. The unit begins with outlines…

  13. 论魏晋经学与文学复古之风%Classical Scholarship in Wei-Jin Period and Restoration of Ancient Literary Tradition

    Institute of Scientific and Technical Information of China (English)

    刘运好; 程平

    2013-01-01

    Confucian classics,especially the Book of Songs,were one of the leading forces shaping the literature of the Wei-Jin Period. In terms of the poetic style,Wei-Jin literature mimicked the Book of Songs,with siyan poems (the poems with each line composed of four Chinese characters)as its major pattern. In terms of the subject matter and theme,Wei-Jin literature directly mimicked the Book of Songs,and created three types of poems:the poems depicting Confucian Classics;the poems supple-menting the missing part of the Book of Songs;the poems parodying the Book of Songs. The fervor of restoring ancient literary tradition reached its peak in that period. In terms of the artistic style,Wei-Jin literature gave priority to ya (odes)and song (hymns),and transformed feng into ya,making a bold exploration of how to inherit the literary tradition of the Book of Songs. Wei-Jin literature forms a key link in the long history of Chinese literature.%经学尤其《诗经》仍然是支撑魏晋文学的主流意识之一。在诗歌体式上,魏晋文学大量摹拟《诗经》,以四言为主;在诗歌题材和主旨上,直接摹拟《诗经》,创造出拟经诗、补亡诗、拟《诗》诗三种类型,复古之风达到了空前炽烈的局面;在艺术风格上,以雅颂为主、又以风入雅,从而对如何继承《诗经》的文学传统提供一次集大成式的探索,在中国文学史上具有承上启下的重要意义。

  14. FT-IR spectroscopy, scanning electron microscopy and porosity measurements to determine the firing temperature of ancient megalithic period potteries excavated at Adichanallur in Tamilnadu, South India

    Science.gov (United States)

    Velraj, G.; Ramya, R.; Hemamalini, R.

    2012-11-01

    Scientific examination of archaeological pottery mainly aims to determine the style of production and the techniques involved in its manufacture. Technological characterization includes the evaluation of the original firing conditions. Maximum firing temperatures may be evaluated by firing clays of compositions similar to those used for the production of the ancient objects. In the present work, some of the ancient pottery samples were collected from recently excavated site at Adichanallur, Tirunelveli District, Tamilnadu, India to estimate the firing temperature of the pottery samples and atmosphere prevailed at the time of manufacturing those potteries by the ancient artisans. From the Fourier transform infrared spectra of the samples the lower limit of firing temperature have been determined. The upper limit of firing temperature was evaluated by porosimetry method. The scanning electron microscopic analysis is used to narrow down the range of firing temperature and the results are consistent with the results obtained from FT-IR spectroscopic study and porosimetry method.

  15. Hunting for Ancient Rocky Shores.

    Science.gov (United States)

    Johnson, Markes E.

    1988-01-01

    Promotes the study of ancient rocky shores by showing how they can be recognized and what directions future research may follow. A bibliography of previous research articles, arranged by geologic period, is provided in the appendix to this paper. (CW)

  16. Dentistry in ancient mesopotamia.

    Science.gov (United States)

    Neiburger, E J

    2000-01-01

    Sumer, an empire in ancient Mesopotamia (southern Iraq), is well known as the cradle of our modern civilization and the home of biblical Abraham. An analysis of skeletal remains from cemeteries at the ancient cities of Ur and Kish (circa 2000 B.C.), show a genetically homogeneous, diseased, and short-lived population. These ancient Mesopotamians suffered severe dental attrition (95 percent), periodontal disease (42 percent), and caries (2 percent). Many oral congenital and neoplastic lesions were noted. During this period, the "local dentists" knew only a few modern dental techniques. Skeletal (dental) evidence indicates that the population suffered from chronic malnutrition. Malnutrition was probably caused by famine, which is substantiated in historic cuneiform and biblical writings, geologic strata samples, and analysis of skeletal and forensic dental pathology. These people had modern dentition but relatively poor dental health. The population's lack of malocclusions, caries, and TMJ problems appear to be due to flat plane occlusion.

  17. Ancient genomics

    DEFF Research Database (Denmark)

    Der Sarkissian, Clio; Allentoft, Morten Erik; Avila Arcos, Maria del Carmen

    2015-01-01

    by increasing the number of sequence reads to billions effectively means that contamination issues that have haunted aDNA research for decades, particularly in human studies, can now be efficiently and confidently quantified. At present, whole genomes have been sequenced from ancient anatomically modern humans......, archaic hominins, ancient pathogens and megafaunal species. Those have revealed important functional and phenotypic information, as well as unexpected adaptation, migration and admixture patterns. As such, the field of aDNA has entered the new era of genomics and has provided valuable information when...

  18. Ancient genomics

    DEFF Research Database (Denmark)

    Der Sarkissian, Clio; Allentoft, Morten Erik; Avila Arcos, Maria del Carmen;

    2015-01-01

    , archaic hominins, ancient pathogens and megafaunal species. Those have revealed important functional and phenotypic information, as well as unexpected adaptation, migration and admixture patterns. As such, the field of aDNA has entered the new era of genomics and has provided valuable information when...

  19. Dwarfs in ancient Egypt.

    Science.gov (United States)

    Kozma, Chahira

    2006-02-15

    Ancient Egypt was one of the most advanced and productive civilizations in antiquity, spanning 3000 years before the "Christian" era. Ancient Egyptians built colossal temples and magnificent tombs to honor their gods and religious leaders. Their hieroglyphic language, system of organization, and recording of events give contemporary researchers insights into their daily activities. Based on the record left by their art, the ancient Egyptians documented the presence of dwarfs in almost every facet of life. Due to the hot dry climate and natural and artificial mummification, Egypt is a major source of information on achondroplasia in the old world. The remains of dwarfs are abundant and include complete and partial skeletons. Dwarfs were employed as personal attendants, animal tenders, jewelers, and entertainers. Several high-ranking dwarfs especially from the Old Kingdom (2700-2190 BCE) achieved important status and had lavish burial places close to the pyramids. Their costly tombs in the royal cemeteries and the inscriptions on their statutes indicate their high-ranking position in Egyptian society and their close relation to the king. Some of them were Seneb, Pereniankh, Khnumhotpe, and Djeder. There were at least two dwarf gods, Ptah and Bes. The god Ptah was associated with regeneration and rejuvenation. The god Bes was a protector of sexuality, childbirth, women, and children. He was a favored deity particularly during the Greco-Roman period. His temple was recently excavated in the Baharia oasis in the middle of Egypt. The burial sites and artistic sources provide glimpses of the positions of dwarfs in daily life in ancient Egypt. Dwarfs were accepted in ancient Egypt; their recorded daily activities suggest assimilation into daily life, and their disorder was not shown as a physical handicap. Wisdom writings and moral teachings in ancient Egypt commanded respect for dwarfs and other individuals with disabilities.

  20. Glacial morphology of Komovi

    Directory of Open Access Journals (Sweden)

    Milivojević Milovan M.

    2004-01-01

    Full Text Available The paper presents the glacial relief on Mt. Komovi in Montenegro. The most common are the macro-glacial forms, which are the best preserved - cirques and moraines. By the analysis of topographic maps and survey in the field the situation, orientation and morphometric data on these forms are given. The analysis of impact of exposures on the cirque bottom elevation is given. Furthermore, the level of preservation of glacial relief forms, depending on geological settings, is analyzed. Finally, there is the reconstruction of Pleistocene snow line elevation and spread of glaciations.

  1. High-resolution Geophysical Mapping of Submarine Glacial Landforms

    Science.gov (United States)

    Jakobsson, M.; Dowdeswell, J. A.; Canals, M.; Todd, B. J.; Dowdeswell, E. K.; Hogan, K. A.; Mayer, L. A.

    2014-12-01

    Glacial landforms are generated from the activity of glaciers and display spatial dimensions ranging from below one meter up to tens of kilometers. Glacial landforms are used as diagnostic features of past activity of ice sheets and glaciers; they are specifically important in the field of palaeoglaciology. Mapping of submarine glacial landforms is largely dependent on geophysical survey methods capable of imaging the seafloor and sub-bottom through the water column. Full "global" seafloor mapping coverage, equivalent to what exists for land elevation, is to-date only achieved by the powerful method of deriving bathymetry from altimeters on satellites like GEOSAT and ERS-1. The lateral resolution of satellite derived bathymetry is, however, limited by the footprint of the satellite and the need to average out local wave and wind effects resulting in values of around 15 km. Consequently, mapping submarine glacial landforms requires for the most part higher resolution than is achievable by satellite derived bathymetry. The most widely-used methods for mapping submarine glacial landforms are based on echo-sounding principles. This presentation shows how the evolution of marine geophysical mapping techniques, in particular the advent of side-scan and multibeam bathymetric sonars, has made it possible to study submarine glacial landforms in unprecedented detail. Examples are shown from the Atlas of Submarine Glacial Landforms: Modern, Quaternary and Ancient, which will be published in late 2015 in the Memoir Series of the Geological Society of London.

  2. Halite as a Methane Sequestration Host: A Possible Explanation for Periodic Methane Release on Mars, and a Surface-accessible Source of Ancient Martian Carbon

    Science.gov (United States)

    Fries, M. D.; Steele, Andrew; Hynek, B. M.

    2015-01-01

    We present the hypothesis that halite may play a role in methane sequestration on the martian surface. In terrestrial examples, halite deposits sequester large volumes of methane and chloromethane. Also, examples of chloromethane-bearing, approximately 4.5 Ga old halite from the Monahans meteorite show that this system is very stable unless the halite is damaged. On Mars, methane may be generated from carbonaceous material trapped in ancient halite deposits and sequestered. The methane may be released by damaging its halite host; either by aqueous alteration, aeolian abrasion, heating, or impact shock. Such a scenario may help to explain the appearance of short-lived releases of methane on the martian surface. The methane may be of either biogenic or abiogenic origin. If this scenario plays a significant role on Mars, then martian halite deposits may contain samples of organic compounds dating to the ancient desiccation of the planet, accessible at the surface for future sample return missions.

  3. Volcanic and glacial evolution of Chachani-Nocarane complex (Southern Peru) deduced from the geomorphologic map.

    Science.gov (United States)

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

    2012-04-01

    The Chachani-Nocarane (16°11'S; 71°31'W; 6.057 m asl) is a large volcanic complex located in the western Central-Andean Cordillera, South of Peru. The date of the last eruption is not known and there are no registers of recent volcanic activity. The complex is shaped by glacial forms belonging to different phases, and periglacial forms (several generations of rock glaciers) which alternate with volcanic forms. The aim of this research is to establish the glacio-volcanic evolution of the volcanic complex Chachani-Nocarane. In order to do so, a detailed 1:20.000 scale geomorphological map was elaborated by integrating the following techniques: interpretation of the 1:35.000 scale aerial photographs (Instituto Geográfico Nacional de Perú, 1956) and the analysis of satellite images (Mrsid; NASA, 2000). Finally, the cartography was corrected though field work campaigns. Through the geomorphologic analysis of the landforms and their relative position, we have identified twelve phases, seven volcanic and five glacial phases. The most ancient volcanic phase is locate to the north area of the study area and correspond with Nocarane and Chingana volcanoes, alignment NW-SE. Above those ensemble the rest of the large delimited geomorphological units overlap. The most recent is located to the SW and consists of a complex series of domes, lava cones and voluminous lavas. Within the glacial phases, the most ancient one is related to the Last Glacial Maximum during the Pleistocene. Over this period, glaciers formed moraines from 3150 to 3600 m asl. The most recent glacier pulsation corresponds to the Little Ice Age (LIA). The moraines related to that event are the closest to the summits, located between 5.100 and 5.300 m asl, and they represent the last trace of glacial activity on the volcanic complex. Currently, this tropical mountain does not have glaciers. The only solid-state water reserves are found in the form of permafrost, as shown by various generations of rock

  4. Preservation of ancient ice at Pavonis and Arsia Mons: Tropical mountain glacier deposits on Mars

    Science.gov (United States)

    Head, James W.; Weiss, David K.

    2014-11-01

    Large tropical mountain glacier (TMG) deposits on the northwest flanks of the Tharsis Montes and Olympus Mons volcanoes are interpreted to be the record of ancient climates characteristic of Mars several hundred million years ago when planetary spin-axis obliquity was ~45°. During this era, polar volatiles (predominantly H2O) were mobilized and transferred equatorward, undergoing adiabatic cooling on the Tharsis volcano flanks, and precipitating snow and ice to form cold-based tropical mountain glaciers up to several kilometers in thickness. Subsequent climate change resulted in retreat, sublimation and collapse of the tropical mountain glaciers, leaving the three typical facies observed today: (1) concentric ridges, the ridged facies, interpreted as drop moraines; (2) knobby facies, interpreted as debris-dominated sublimation residue; and (3) the smooth facies, interpreted as remnant alpine glacial deposits. Ring-mold craters (RMCs) are distinctive features formed by impacts into debris-covered ice. We describe a set of relatively fresh ring-mold craters superposed on the Arsia and Pavonis Mons TMG deposits; we interpret these to indicate that the impact events penetrated a veneer of sublimation lag and excavated buried remnant glacial ice, despite the lack of detection of buried ice by orbital radar instruments. The diameter distribution of the RMCs suggest that the remnant ice lies at a depth of at least 16 m. The TMG deposit ages suggest that these ice deposits date from a period in the range of 125-220 million years before the present; the remnant ice may thus preserve records of the ancient atmospheric gas content and microbiota, as is common in terrestrial glacial ice. Preservation of this ice and the lack of any associated fluvial features suggest that the post-glacial climate has been cold, and related surface temperatures have not been sufficient to bring the buried deposits to the melting point of water.

  5. Cause of Global Climate Change and Alternation of Glacial and Interglacial Periods as well as Their Computations%全球气候变化及冰期与间冰期交替的原因及其计算

    Institute of Scientific and Technical Information of China (English)

    钟萃相

    2014-01-01

    许多科学家都怀疑温室气体的排放是全球变暖的主要因素,他们认为自然驱动才是全球气候变化的主要因素,但他们并未找出具有说服力的自然驱动力。于是作者研究了各种可能引起气候变化的自然驱动力,发现火山活动能改变地球的轨道,因而是引起气候明显变化的关键因素。其中主要推导了火山喷发改变地球转速的公式以及地球变速引起地球变轨的公式。根据这些公式,通过计算机的高精度计算可以发现一定规模的火山喷发确实能使地球变轨,从而使全球变冷或变暖,甚至进入冰期或间冰期。因此,解决了气候变暖以及冰期与间冰期交替的成因问题,并找出了相应的对策。%Many scientists are skeptical about that the emission of greenhouse gases is the primary factor in global climate change, and they believe natural driving is the main factor for global climate change, but they haven’t found such a convincing natural driving force yet. So the author has researched deeply into various natural forces that could affect climate change,and found that volcanism can obviously alter the orbit of the Earth and therefore is another key factor for climate change. This research mainly includes the derivation of a formula on volcanic eruption changing the earth’s revolution speed and another formula on the earth’s revolution speed variation causing the Earth’s orbital transfer. According to these formulas, through computer’s high precision computation, the author found that volcanic eruptions at a certain scale can indeed cause the Earth’s orbital variation, thus causing global warming or cooling, even making the Earth enter an interglacial period or a glacial period. Hence, this research has solved the cause-problem of global warming as well as the cause-problem of the alternation of glacial and interglacial periods, and also found the corresponding strategies.

  6. 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...

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

    OpenAIRE

    Tao Che; Lin Xiao; Yuei-An Liou

    2014-01-01

    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...

  8. Glacial-interglacial vegetation change in the Zambezi catchment

    Science.gov (United States)

    Dupont, L. M.; Kuhlmann, H.

    2017-01-01

    Changes in the environment are thought to have had strong impact on human evolution. The pollen record of GeoB9311, retrieved offshore of the Zambezi River mouth, indicates glacial-interglacial changes in the vegetation of southern East Africa with enhanced forests in the coastal area during interglacials, more Afromontane forest and ericaceous bushland during glacials and an increase in mopane woodland during the transitional periods. C4 swamps, probably with papyrus, might have spread during the more humid phases of the glacial, while mangroves responded sensitively to changes in sea level. The spread of open ericaceous bushland and Afromontane forest during glacials is found for most of Southern Africa with the exception of the extreme south and southwest regions. In contrast to the western part of the continent, forest and woodland in East Africa did not completely disappear during the glacial. It seems that on a regional scale climatic perturbations of the vegetation are less severe than in West Africa.

  9. The influence of glacial ice sheets on Atlantic meridional overturning circulation through atmospheric circulation change under glacial climate

    Science.gov (United States)

    Sherriff-Tadano, Sam; Abe-Ouchi, Ayako; Yoshimori, Masakazu; Oka, Akira; Chan, Wing-Le

    2016-04-01

    Recent coupled modeling studies have shown that the existence of the glacial ice sheets intensifies the Atlantic meridional overturning circulation (AMOC). Since this may play an important role in maintaining a strong AMOC over the last glacial period, which is suggested by recent reconstruction study, it is very important to understand the process by which glacial ice sheets intensify the AMOC. Here, a decoupled simulation is conducted to investigate the effect of wind change due to glacial ice sheets on the AMOC, the crucial region where wind modifies the AMOC and the mechanism, which remained elusive in previous studies. First, from atmospheric general circulation model (AGCM) experiments, the effect of glacial ice sheets on the surface wind is evaluated. Second, from ocean general circulation model (OGCM) experiments, the influence of the wind stress change on the AMOC is evaluated by applying only the changes in the surface wind as a boundary condition, while leaving surface heat and freshwater fluxes unchanged. Moreover, several sensitivity experiments are conducted. Using the AGCM, glacial ice sheets are applied individually. Using the OGCM, changes in the wind are applied regionally or at different magnitudes, ranging from the full glacial to modern levels. These experiments demonstrate that glacial ice sheets intensify the AMOC through an increase in the wind stress curl mainly at the North Atlantic mid-latitudes. This intensification is caused by the increased Ekman upwelling and gyre transport of salt while the change in sea ice transport works as a negative, though minor, feedback.

  10. 战国作者的托名传播%On Authors of the Warring States Period Who Disseminate Their Own Works on the Pretext of the Ancient and Modern Celebrities

    Institute of Scientific and Technical Information of China (English)

    陈桐生

    2012-01-01

    The so-called "on the pretext of the name of others" means that authors disseminated their own works on the pretext of the ancient and modem celebrities. The practice was based on the authors' signatures. From Shang and Zhou Dynasties to Spring and Autumn Period, because the authors had no consciousness of signing their names on their works there were no problems in signa- ture. The awakening of authors' signature began in the Warring States Period, because works could bring tremendous spirit honors and material rewards to authors, and it is necessary to distinguish be- tween school, those who wants to make themselves more famous also disseminated their own works on the pretext of the ancient and modem celebrities. The practice of the so - called "on the pretext of the name of others" could be roughly divided into four categories :first ,on the pretext of the name of the real people;second, on the pretext of the name of historical figures;third, on the pretext of the name of the legendary figures ; fourth, the works of the disciples and followers were signed by others. Authors' disseminating their works on the pretext of the name of others made great achievements in the Warring States Period, and many works were handed down with the help of ancient and modem celebrity effect. Some of them have significant academic value. This practice affects the later ages, and obscures certain links of history of Chinese literature, causing a lot of problems in distinguishing authenticity of ancient works.%所谓托名,是指作者假托古今名流传播自己的作品。托名现象的产生以作品署名为前提。从商周到春秋时期,由于作者的署名意识没有觉醒,因此不存在署名问题。作者署名意识的觉醒始于战国,由于作品可以给作者带来巨大的精神荣誉和物质奖赏,同时也是出于区分学派的需要,战国作者开始在自己的作品上署名。有些作者考虑到自己声名不够,为了使自己

  11. Did the ancient Egyptians migrate to ancient Nigeria?

    Directory of Open Access Journals (Sweden)

    Jock M. Agai

    2014-01-01

    Full Text Available Literatures concerning the history of West African peoples published from 1900 to 1970 debate�the possible migrations of the Egyptians into West Africa. Writers like Samuel Johnson and�Lucas Olumide believe that the ancient Egyptians penetrated through ancient Nigeria but Leo�Frobenius and Geoffrey Parrinder frowned at this opinion. Using the works of these early�20th century writers of West African history together with a Yoruba legend which teaches�about the origin of their earliest ancestor(s, this researcher investigates the theories that the�ancient Egyptians had contact with the ancient Nigerians and particularly with the Yorubas.Intradisciplinary and/or interdisciplinary implications: There is an existing ideology�amongst the Yorubas and other writers of Yoruba history that the original ancestors of�the Yorubas originated in ancient Egypt hence there was migration between Egypt and�Yorubaland. This researcher contends that even if there was migration between Egypt and�Nigeria, such migration did not take place during the predynastic and dynastic period as�speculated by some scholars. The subject is open for further research.

  12. 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.

  13. [Paleopathology of ancient Egyptian mummies and skeletons. Investigations on the occurrence and frequency of specific diseases during various time periods in the necropolis of Thebes-West].

    Science.gov (United States)

    Nerlich, A G; Rohrbach, H; Zink, A

    2002-09-01

    The scientific investigation of mummies and skeletons provides considerable data for the reconstruction of the living conditions and diseases of past populations. We describe the data on four completely analyzed tomb complexes from the huge necropolis of Thebes-West in Upper Egypt dating to different time periods. A total of 211 individuals from the so-called "Middle Kingdom" (MK, c. 2050-1750 BC) were compared to 273 individuals from the "New Kingdom" (NK) to "Late Period" (LP, in total 1550-500 BC). The age at death and the sex ratio were comparable between both groups. There was a high rate of early death with a maximum between the 2nd and 3rd decade of life but infant/adolescent burials were comparably rare. This early death is assumed to be due to an elevated prevalence of various infectious diseases. Likewise, a high rate of tuberculosis infections was seen in those individuals regardless of which time period they came from. Metabolic disorders with osseous manifestations, such as scurvy, osteomalacia and chronic anemia (cribra orbitalia, porotic hyperostosis) were found with a high frequency in the MK populations but significantly less in the NK-LP populations. On the other hand signs of trauma were comparably high, and lesions due to degenerative joint and vertebral diseases were significantly higher in LP than in MK or NK individuals suggesting a higher mechanical load in the later populations. Cases of malignant (secondary) bone tumors and various soft tissue/organ diseases indicate that "civilization" disorders were present when the living conditions assured survival into advanced age. In summary, we provide circumstantial evidence that the systematic and concise analysis of mummy and skeletal remains can allow a reconstruction of major aspects of life and disease in historic populations, although a complete reconstruction is not possible.

  14. Sub-pluvial Saqqara and its possible impact on ancient Egyptian civilization in the Old Kingdom Period (4600 - 4100 yrs BP)

    Science.gov (United States)

    Welc, Fabian; Marks, Leszek

    2014-05-01

    Geological and geoarchaeological investigations were carried out at several archaeological sites in northern Egypt within the Memphis Necropolis (Saqqara, Abusir, and Giza). Sedimentological analysis of exposures in western Saqqara, excavated by the Polish-Egyptian archaeological team led by Professor Karol Myśliwiec (Institute of Mediterranean and Oriental Cultures, Polish Academy of Sciences), supplied with significant paleoclimatic data and enabled reconstruction of regional climate change during the Old Kingdom Period (4600 - 4100 yrs BP). Potential influence of this climate change on development of the early Egyptian civilization in this area was determined. Examined exposures indicated that during the Old Kingdom Period the area of Saqqara (at present located in a desert) has been many a time flooded with sheet floods, water of which was heavily charged with debris moving down-slope. Performed geochemical and sedimentological analyses proved that climate in the Old Kingdom time was warm and relatively wet. In 4200 - 4100 yrs BP a quick climate change from wet to extremely dry occurred, with occasional stormy winds. These unfavorable climatic conditions were accompanied by catastrophically low seasonal floods of the Nile, resulting in famine and drought recorded in archaeological data and consequently, leading to a disintegration of the Egyptian state. The authors' investigations indicated that a climate change in Egypt in the second half of the 3rd millennium BC is however not as univocal as considered previously. Well-known gradual aridification of the north-eastern Africa, initiated about 5000 yrs BP, has not been unidirectional and was varied regionally. The collected data indicate univocally that there were quasi-cyclic climatic fluctuations. In spite of a distinct trend, the dry period has been interrupted by numerous short wet episodes, occurring during the interval 4600 - 4200 yrs BP and especially at the end of the Old Kingdom Period (ca. 4200 yrs BP

  15. Mechanisms in ancient Chinese books with illustrations

    CERN Document Server

    Hsiao, Kuo-Hung

    2014-01-01

    This book presents a unique approach for studying mechanisms and machines with drawings that were depicted unclearly in ancient Chinese books. The historical, cultural and technical backgrounds of the mechanisms are explained, and various mechanisms described and illustrated in ancient books are introduced. By utilizing the idea for the conceptual design of modern mechanisms, all feasible designs of ancient mechanisms with uncertain members and joints that meet the technical standards of the subjects’ time periods are synthesized systematically. Ancient Chinese crossbows (the original crossbow and repeating crossbows), textile mechanisms (silk-reeling mechanism, spinning mechanisms, and looms), and many other artisan's tool mechanisms are used as illustrated examples.  Such an approach provides a logical method for the reconstruction designs of ancient mechanisms with uncertain structures. It also provides an innovative direction for researchers to further identify the original structures of mechanisms...

  16. Ancient buried valleys in the city of Tallinn and adjacent area

    Directory of Open Access Journals (Sweden)

    Vaher, Rein

    2010-03-01

    Full Text Available The distribution, morphology, fillings, and origin of buried valleys are discussed. The direction of the valleys varies from NW to NE. Within the Viru-Harju Plateau the valleys have a more or less symmetric profile, but asymmetric profiles are dominating in the pre-klint area. They are mainly filled with glacial (till, glaciofluvial (sand, gravel, and pebbles, glacio­lacustrine (varved clay, and marine (fine-grained sand deposits. The Tallinn valley with its tributary valleys (Saku and Sausti and fore-klint branches (Harku, Lilleküla, and Kadriorg looks like a river system. The fore-klint branches extend over 20 km in the Gulf of Finland. They are probably tributaries of the ancient river Pra-Neva. Most likely, the formation of valleys was continuous, starting from pre-Quaternary river erosion, and was sculptured by variable processes during the ice ages and influenced by flowing water during the interglacial periods.

  17. Glacial Features (Point) - Quad 184 (KINGSTON, 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,...

  18. 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,...

  19. Glacial Features (Point) - Quad 154 (BARRINGTON, 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. Glacial Features (Point) - Quad 166 (CANDIA, 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,...

  1. Glacial Features (Point) - Quad 169 (NEWMARKET, 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,...

  2. Surgical history of ancient China: Part 2.

    Science.gov (United States)

    Fu, Louis

    2010-03-01

    In this second part of ancient Chinese surgical history, the practice of bone setting in China began around 3000 years ago. Throughout this period, significant progress was made, some highlights of which are cited. These methods, comparable with Western orthopaedic technique, are still being practised today. In conclusion, the possible reasons for the lack of advancement in operative surgery are discussed, within context of the cultural, social and religious background of ancient China.

  3. Late Glacial ice advances in southeast Tibet

    Science.gov (United States)

    Strasky, Stefan; Graf, Angela A.; Zhao, Zhizhong; Kubik, Peter W.; Baur, Heinrich; Schlüchter, Christian; Wieler, Rainer

    2009-03-01

    The sensitivity of Tibetan glacial systems to North Atlantic climate forcing is a major issue in palaeoclimatology. In this study, we present surface exposure ages of erratic boulders from a valley system in the Hengduan Mountains, southeastern Tibet, showing evidence of an ice advance during Heinrich event 1. Cosmogenic nuclide analyses ( 10Be and 21Ne) revealed consistent exposure ages, indicating no major periods of burial or pre-exposure. Erosion-corrected (3 mm/ka) 10Be exposure ages range from 13.4 to 16.3 ka. This is in agreement with recalculated exposure ages from the same valley system by [Tschudi, S., Schäfer, J.M., Zhao, Z., Wu, X., Ivy-Ochs, S., Kubik, P.W., Schlüchter, C., 2003. Glacial advances in Tibet during the Younger Dryas? Evidence from cosmogenic 10Be, 26Al, and 21Ne. Journal of Asian Earth Sciences 22, 301-306.]. Thus this indicates that local glaciers advanced in the investigated area as a response to Heinrich event 1 cooling and that periglacial surface adjustments during the Younger Dryas overprinted the glacial morphology, leading to deceptively young exposure ages of certain erratic boulders.

  4. Population dynamics and genetic changes of Picea abies in the South Carpathians revealed by pollen and ancient DNA analyses

    Directory of Open Access Journals (Sweden)

    Braun Mihály

    2011-03-01

    Full Text Available Abstract Background Studies on allele length polymorphism designate several glacial refugia for Norway spruce (Picea abies in the South Carpathian Mountains, but infer only limited expansion from these refugia after the last glaciation. To better understand the genetic dynamics of a South Carpathian spruce lineage, we compared ancient DNA from 10,700 and 11,000-year-old spruce pollen and macrofossils retrieved from Holocene lake sediment in the Retezat Mountains with DNA extracted from extant material from the same site. We used eight primer pairs that amplified short and variable regions of the spruce cpDNA. In addition, from the same lake sediment we obtained a 15,000-years-long pollen accumulation rate (PAR record for spruce that helped us to infer changes in population size at this site. Results We obtained successful amplifications for Norway spruce from 17 out of 462 pollen grains tested, while the macrofossil material provided 22 DNA sequences. Two fossil sequences were found to be unique to the ancient material. Population genetic statistics showed higher genetic diversity in the ancient individuals compared to the extant ones. Similarly, statistically significant Ks and Kst values showed a considerable level of differentiation between extant and ancient populations at the same loci. Lateglacial and Holocene PAR values suggested that population size of the ancient population was small, in the range of 1/10 or 1/5 of the extant population. PAR analysis also detected two periods of rapid population growths (from ca. 11,100 and 3900 calibrated years before present (cal yr BP and three bottlenecks (around 9180, 7200 and 2200 cal yr BP, likely triggered by climatic change and human impact. Conclusion Our results suggest that the paternal lineages observed today in the Retezat Mountains persisted at this site at least since the early Holocene. Combination of the results from the genetic and the PAR analyses furthermore suggests that the higher

  5. Uncertainty in Greenland glacial isostatic adjustment

    DEFF Research Database (Denmark)

    Milne, G. A.; Lecavalier, B.; Kjeldsen, K. K.;

    changes (commonly referred to as glacial isostatic adjustment (GIA)) can be defined. Predictions based on a new model of Greenland GIA will be shown. Using these predictions as a reference, we will consider the influence of plausible variations in some key aspects of both the Earth and ice load components...... of the GIA model on predictions of land motion and gravity changes. The sensitivity of model output to plausible variations in both depth-dependent and lateral viscosity structure will be considered. With respect to the ice model, we will compare the relative contributions of loading during key periods...

  6. Ancient DNA from marine mammals

    DEFF Research Database (Denmark)

    Foote, Andrew David; Hofreiter, Michael; Morin, Philip A

    2012-01-01

    such as bone, tooth, baleen, skin, fur, whiskers and scrimshaw using ancient DNA (aDNA) approaches provide an oppor- tunity for investigating such changes over evolutionary and ecological timescales. Here, we review the application of aDNA techniques to the study of marine mammals. Most of the studies have...... focused on detecting changes in genetic diversity following periods of exploitation and environmental change. To date, these studies have shown that even small sample sizes can provide useful information on historical genetic diversity. Ancient DNA has also been used in investigations of changes...... in distribution and range of marine mammal species; we review these studies and discuss the limitations of such ‘presence only’ studies. Combining aDNA data with stable isotopes can provide further insights into changes in ecology and we review past studies and suggest future potential applications. We also...

  7. Radiocarbon dating of ancient Japanese documents

    Energy Technology Data Exchange (ETDEWEB)

    Oda, H. [Nagoya Univ., Center for Chronological Research, Nagoya, Aichi (Japan)

    2001-06-01

    History is a reconstruction of past human activity, evidence of which is remained in the form of documents or relics. For the reconstruction of historic period, the radiocarbon dating of ancient documents provides important information. Although radiocarbon age is converted into calendar age with the calibration curve, the calibrated radiocarbon age is still different from the historical age when the document was written. The difference is known as 'old wood effect' for wooden cultural property. The discrepancy becomes more serious problem for recent sample which requires more accurate age determination. Using Tandetron accelerator mass spectrometer at Nagoya University, we have measured radiocarbon ages of Japanese ancient documents, sutras and printed books written dates of which are clarified from the paleographic standpoint. The purpose is to clarify the relation between calibrated radiocarbon age and historical age of ancient Japanese document by AMS radiocarbon dating. This paper reports 23 radiocarbon ages of ancient Japanese documents, sutras and printed books. The calibrated radiocarbon ages are in good agreement with the corresponding historical ages. It was shown by radiocarbon dating of the ancient documents that Japanese paper has little gap by 'old wood effect'; accordingly, ancient Japanese paper is a suitable sample for radiocarbon dating of recent historic period. (author)

  8. Somma-Vesuvius ground deformation over the last glacial cycle

    Science.gov (United States)

    Marturano, Aldo; Aiello, Giuseppe; Barra, Diana

    2013-04-01

    Vertical ground movements at Somma-Vesuvius during the last glacial cycle have been inferred from micropalaeontological and petrochemical analyses of rock samples from boreholes drilled at the archaeological sites of Herculaneum and Pompeii as well as on the apron of the volcano and the adjacent Sebeto and Sarno Valleys. Opposing movements occurred during the periods preceding and following the Last Glacial Maximum (LGM). The uplift began 20 ka ago with marine deposits rising several tens of metres up to 25 m a.s.l., recovering previous subsidence which occurred during the Late glacial period, suggesting a strict connection between volcano-tectonic and glacial cycles. Here we present the analysis of deposits predating the LGM, which confirms subsidence of the Campanian Plain where Mt. Somma-Vesuvius is located, shows variable surface loading effects and highlights the volcano-tectonic stages experienced by the volcano. The self-balancing mechanism of the volcanic system, evolving towards an explosive, subaerial activity 60 ka ago, is testified to by a large ground oscillation in phase with sea level change during the last glacial cycle.

  9. Ancient Astronomy in Armenia

    Science.gov (United States)

    Parsamian, Elma S.

    2007-08-01

    The most important discovery, which enriched our knowledge of ancient astronomy in Armenia, was the complex of platforms for astronomical observations on the Small Hill of Metzamor, which may be called an ancient “observatory”. Investigations on that Hill show that the ancient inhabitants of the Armenian Highlands have left us not only pictures of celestial bodies, but a very ancient complex of platforms for observing the sky. Among the ancient monuments in Armenia there is a megalithic monument, probably, being connected with astronomy. 250km South-East of Yerevan there is a structure Zorats Kar (Karahunge) dating back to II millennium B.C. Vertical megaliths many of which are more than two meters high form stone rings resembling ancient stone monuments - henges in Great Britain and Brittany. Medieval observations of comets and novas by data in ancient Armenian manuscripts are found. In the collection of ancient Armenian manuscripts (Matenadaran) in Yerevan there are many manuscripts with information about observations of astronomical events as: solar and lunar eclipses, comets and novas, bolides and meteorites etc. in medieval Armenia.

  10. Effects of global warming on ancient mammalian communities and their environments.

    Directory of Open Access Journals (Sweden)

    Larisa R G DeSantis

    Full Text Available BACKGROUND: Current global warming affects the composition and dynamics of mammalian communities and can increase extinction risk; however, long-term effects of warming on mammals are less understood. Dietary reconstructions inferred from stable isotopes of fossil herbivorous mammalian tooth enamel document environmental and climatic changes in ancient ecosystems, including C(3/C(4 transitions and relative seasonality. METHODOLOGY/PRINCIPAL FINDINGS: Here, we use stable carbon and oxygen isotopes preserved in fossil teeth to document the magnitude of mammalian dietary shifts and ancient floral change during geologically documented glacial and interglacial periods during the Pliocene (approximately 1.9 million years ago and Pleistocene (approximately 1.3 million years ago in Florida. Stable isotope data demonstrate increased aridity, increased C(4 grass consumption, inter-faunal dietary partitioning, increased isotopic niche breadth of mixed feeders, niche partitioning of phylogenetically similar taxa, and differences in relative seasonality with warming. CONCLUSION/SIGNIFICANCE: Our data show that global warming resulted in dramatic vegetation and dietary changes even at lower latitudes (approximately 28 degrees N. Our results also question the use of models that predict the long term decline and extinction of species based on the assumption that niches are conserved over time. These findings have immediate relevance to clarifying possible biotic responses to current global warming in modern ecosystems.

  11. Discovery of Quaternary glacial evidence of Snow Mountain in Taiwan,China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    There are glacial remains of three different periods on the main peak of Snow Mountain in Taiwan province,including cirque lake,crosswall,polished surface,striation,moraine etc.These three different periods were called,respectively,Shanzhuang ((44.25 ± 3.72) kaBP),Shuiyuan ((18.26 ± 1.52) kaBP),and Xueshan glacial stages (the late period of last glaciation).It is characterized by the earlier glacier broad in scale.

  12. Variations in glacial and interglacial marine conditions over the last two glacial cycles off northern Greenland

    Science.gov (United States)

    Löwemark, Ludvig; Chao, Weng-Si; Gyllencreutz, Richard; Hanebuth, Till J. J.; Chiu, Pin-Yao; Yang, Tien-Nan; Su, Chih-Chieh; Chuang, Chih-Kai; León Dominguez, Dora Carolina; Jakobsson, Martin

    2016-09-01

    Five sediment cores from the Lomonosov Ridge and the Morris Jesup Rise north of Greenland show the history of sea-ice coverage and primary productivity over the last two glacial cycles. Variations in Manganese content, benthic and planktonic foraminifera, bioturbation, and trace fossil diversity are interpreted to reflect differences in sea-ice cover and sediment depositional conditions between the identified interglacials. Marine Isotope Stage (MIS) 1 and MIS 2 are represented by thin (ice conditions north of Greenland while MIS 5 appears to have been considerably warmer with more open water, higher primary productivity, and higher sedimentation rates. Strengthened flow of Atlantic water along the northern continental shelf of Greenland rather than development of local polynyas is here suggested as a likely cause for the relatively warmer marine conditions during MIS 5 compared to MIS 1. The cores also suggest distinct differences between the glacial intervals MIS 2 and MIS 6. While MIS 6 is distinguished by a relatively thick sediment unit poor in foraminifera and with low Mn values, MIS 2 is practically missing. We speculate that this could be the effect from a paleocrystic sea-ice cover north of Greenland during MIS 2 that prevented sediment delivery from sea ice and icebergs. In contrast, the thick sequence deposited during MIS 6 indicates a longer glacial period with dynamic intervals characterized by huge drifting icebergs delivering ice rafted debris (IRD). A drastic shift from thinner sedimentary cycles where interglacial sediment parameters indicate more severe sea-ice conditions gave way to larger amplitude cycles with more open water indicators was observed around the boundary between MIS 7/8. This shift is in agreement with a sedimentary regime shift previously identified in the Eurasian Basin and may be an indicator for the growth of larger ice sheets on the Eurasian landmass during the penultimate glacial period.

  13. Tectonic control on the persistence of glacially sculpted topography.

    Science.gov (United States)

    Prasicek, Günther; Larsen, Isaac J; Montgomery, David R

    2015-08-14

    One of the most fundamental insights for understanding how landscapes evolve is based on determining the extent to which topography was shaped by glaciers or by rivers. More than 10(4) years after the last major glaciation the topography of mountain ranges worldwide remains dominated by characteristic glacial landforms such as U-shaped valleys, but an understanding of the persistence of such landforms is lacking. Here we use digital topographic data to analyse valley shapes at sites worldwide to demonstrate that the persistence of U-shaped valleys is controlled by the erosional response to tectonic forcing. Our findings indicate that glacial topography in Earth's most rapidly uplifting mountain ranges is rapidly replaced by fluvial topography and hence valley forms do not reflect the cumulative action of multiple glacial periods, implying that the classic physiographic signature of glaciated landscapes is best expressed in, and indeed limited by, the extent of relatively low-uplift terrain.

  14. Damping of glacial-interglacial cycles from anthropogenic forcing

    CERN Document Server

    Haqq-Misra, Jacob

    2014-01-01

    Climate variability over the past million years shows a strong glacial-interglacial cycle of ~100,000 years as a combined result of Milankovitch orbital forcing and climatic resonance. It has been suggested that anthropogenic contributions to radiative forcing may extend the length of the present interglacial, but the effects of anthropogenic forcing on the periodicity of glacial-interglacial cycles has received little attention. Here I demonstrate that moderate anthropogenic forcing can act to damp this 100,000 year cycle and reduce climate variability from orbital forcing. Future changes in solar insolation alone will continue to drive a 100,000 year climate cycle over the next million years, but the presence of anthropogenic warming can force the climate into an ice-free state that only weakly responds to orbital forcing. Sufficiently strong anthropogenic forcing that eliminates the glacial-interglacial cycle may serve as an indication of an epoch transition from the Pleistocene to the Anthropocene.

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

    Science.gov (United States)

    Jansen, Malte F.

    2017-01-01

    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.

  16. Ancient Marital Rites

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    Clearly defined rites governing speech and actions dominated both the social and domestic activities of ancient Chinese people. Rites not only dominated the lives of men, but were also prominent in the lives of women.

  17. Ancient Chinese Architecture

    Institute of Scientific and Technical Information of China (English)

    1993-01-01

    CHINESE people have accu-mulated a great deal ofexperience in architecture,constantly improving building ma-terials and thus creating uniquebuilding styles.The history of ancient Chinesearchitechtural development can be

  18. The Ancient stellar population of Leo A.

    NARCIS (Netherlands)

    Saha, Abhijit; Fiorentino, Giuliana; Tolstoy, Eline; Cole, Andrew

    2010-01-01

    The primary goal of our proposal is the characterisation of the oldest stellar populations in Leo A using the properties of ancient RR Lyrae variable stars as tracers. Well known and long established correlations exist between the periods and luminosities of RR Lyrae variable stars and their ages an

  19. Glacial refugia and modern genetic diversity of 22 western North American tree species.

    Science.gov (United States)

    Roberts, David R; Hamann, Andreas

    2015-04-07

    North American tree species, subspecies and genetic varieties have primarily evolved in a landscape of extensive continental ice and restricted temperate climate environments. Here, we reconstruct the refugial history of western North American trees since the last glacial maximum using species distribution models, validated against 3571 palaeoecological records. We investigate how modern subspecies structure and genetic diversity corresponds to modelled glacial refugia, based on a meta-analysis of allelic richness and expected heterozygosity for 473 populations of 22 tree species. We find that species with strong genetic differentiation into subspecies had widespread and large glacial refugia, whereas species with restricted refugia show no differentiation among populations and little genetic diversity, despite being common over a wide range of environments today. In addition, a strong relationship between allelic richness and the size of modelled glacial refugia (r(2) = 0.55) suggest that population bottlenecks during glacial periods had a pronounced effect on the presence of rare alleles.

  20. Enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands: A sink for atmospheric CO2

    Science.gov (United States)

    Wan, Shiming; Clift, Peter D.; Zhao, Debo; Hovius, Niels; Munhoven, Guy; France-Lanord, Christian; Wang, Yinxi; Xiong, Zhifang; Huang, Jie; Yu, Zhaojie; Zhang, Jin; Ma, Wentao; Zhang, Guoliang; Li, Anchun; Li, Tiegang

    2017-03-01

    Atmospheric CO2 and global climate are closely coupled. Since 800 ka CO2 concentrations have been up to 50% higher during interglacial compared to glacial periods. Because of its dependence on temperature, humidity, and erosion rates, chemical weathering of exposed silicate minerals was suggested to have dampened these cyclic variations of atmospheric composition. Cooler and drier conditions and lower non-glacial erosion rates suppressed in situ chemical weathering rates during glacial periods. However, using systematic variations in major element geochemistry, Sr-Nd isotopes and clay mineral records from Ocean Drilling Program Sites 1143 and 1144 in the South China Sea spanning the last 1.1 Ma, we show that sediment deposited during glacial periods was more weathered than sediment delivered during interglacials. We attribute this to subaerial exposure and weathering of unconsolidated shelf sediments during glacial sealevel lowstands. Our estimates suggest that enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands can account for ∼9% of the carbon dioxide removed from the atmosphere during the glacial and thus represent a significant part of the observed glacial-interglacial variation of ∼80 ppmv. As a result, if similar magnitudes can be identified in other tropical shelf-slope systems, the effects of increased sediment exposure and subsequent silicate weathering during lowstands could have potentially enhanced the drawdown of atmospheric CO2 during cold stages of the Quaternary. This in turn would have caused an intensification of glacial cycles.

  1. The morphological characteristics of glacial deposits during the Last Glaciation, taking the Parlung Zangbo River Basin as an example

    Institute of Scientific and Technical Information of China (English)

    RenRong Chen; ShangZhe Zhou; YingBin Deng

    2013-01-01

    Moraine morphology is a valuable indicator of climate change. The glacial deposits of ten valleys were selected in the Parlung Zangbo River Basin, southeastern Tibetan Plateau, to study the glacial characteristics of the Last Glaciation and the climate change processes as revealed by these moraines. Investigation revealed that a huge moraine ridge was formed by ancient glacier in the Marine Isotope Stage 2 (MIS2), and this main moraine ridge indicates the longest sustained and stable climate. There are at least two smaller moraine ridges that are external extensions of or located at the bottom of the main moraine ridge, indicating that the climate of the glacial stage before MIS2 was severer but the duration was relatively shorter. This distribution may reflect the climate of MIS4 or MIS3b. The glacial valleys show multi-channel, small-scale moraine ridges between the contemporary glacial tongue and the main moraine ridge. Some of these multi-channel mo-raine ridges might be recessional moraine, indicating the significant glacial advance during the Younger Dryas or the Heinrich event. The moraine ridges of the Neoglaciation and the Little Ice Age are near the ends of the contemporary glaciers. Using high-precision system dating, we can fairly well reconstruct the pattern of climate change by studying the shape, extent, and scale characteristics of glacial deposits in southeastern Tibet. This is valuable research to understand the relationship between regional and global climate change.

  2. Mid-late Pleistocene glacial evolution in the Grove Mountains, East Antarctica, constraints from cosmogenic 10Be surface exposure dating of glacial erratic cobbles

    Science.gov (United States)

    Dong, Guocheng; Huang, Feixin; Yi, Chaolu; Liu, Xiaohan; Zhou, Weijian; Caffee, Marc W.

    2016-08-01

    Glacial histories from the East Antarctic Ice Sheet (EAIS) provide keys to understanding correlations between the EAIS and global climate. They are especially helpful in the assessment of global sea level change, and as a means of quantifying the magnitude of past glacial activity and the rate at which ice responded to climate change. Given the significance of EAIS glacial histories, it is imperative that more glacial chronologic data for this region be obtained, especially for the mid-to-late Pleistocene. We report cosmogenic 10Be surface exposure dating results from glacially transported cobbles embedded in blue-ice moraine material at Mount Harding, the Grove Mountains, EAIS. Forty exotic cobbles sampled along two profiles (A and B) on this blue-ice moraine present apparent exposure-ages ranging from 7.2 to 542.2 ka. We explore this scattered dataset by using Principal Component Analysis (PCA) to identify statistically significant trends in the data. We identify a correlation between exposure-age and distance of the cobbles from Mount Harding. In profile A, cobbles further from Mount Harding yield older exposure-ages than those that are relatively close. In profile B, cobbles closer to Mount Harding are found to have relatively older exposure-ages. In term of glacial history we suggest that the direction of ice flow changed during the period from ∼60 to 200 ka, and that multiple glacial fluctuations occurred in the mid-late Pleistocene.

  3. Glacial Cycles and Milankovitch Forcing

    CERN Document Server

    Raghuraman, Shiv Priyam

    2015-01-01

    Using a recent conceptual model of the glacial-interglacial cycles we present more evidence of Milankovitch cycles being the trigger for retreat and forming of ice sheets in the cycles. This model is based on a finite approximation of an infinite dimensional model which has three components: Budyko's energy balance model describing the annual mean temperatures at latitudes, Widiasih's ODE which describes the behavior of the edge of the ice sheet, and Walsh et al. who introduced a snow line to account for glacial accumulation and ablation zones. Certain variables in the model are made to depend on the Milankovitch cycles, in particular, the obliquity of the Earth's axis and the eccentricity of the Earth's orbit. We see as a result that deglaciation and glaciation do occur mostly due to obliquity and to some extent eccentricity.

  4. Dynamic ancient ice caps in the sub-Antarctic suggested by new mapping of submarine ice-formed landscapes

    Science.gov (United States)

    Graham, Alastair; Hodgson, Dominic; Cofaigh, Colm Ó.; Hillenbrand, Claus-Dieter; Kuhn, Gerhard

    2014-05-01

    Recent bathymetric investigations have provided hints of significant past glaciations on several Southern Ocean sub-polar islands. The extent and behaviour of ice cover in these regions is important because it provides critical limits on the evolution of refugia and marine benthic organisms, as well as unique far-field constraints for improving polar ice-sheet model sensitivity. However, despite improvements in regional mapping, sea-floor acoustic data from key shelf areas have still not been of sufficient quality, or broad enough in their coverage, to resolve the number, form or flow of past glacial episodes. Hence the history and style of sub-Antarctic glaciation remains poorly known. Here we use a compilation of multibeam bathymetry and fisheries echo-sounding data to provide evidence for dynamic, widespread ice caps on sub-Antarctic South Georgia during past glacial periods. We present a hitherto unmapped record of sea-bed glacigenic structures, including end moraines and subglacial landforms, from which the flow and form of at least three major, entirely marine-terminating configurations is resolved. The largest glaciation covered the majority of the continental shelf, and included fast-flowing outlets, possible switching of internal flow, meltwater activity, warm-based ice erosion, and substantial marginal deposition during retreat: all features of dynamic ice-cap behaviour. Existing biological evidence suggests the largest glaciation likely pre-dated the Last Glacial Maximum, which may have been restricted in extent reaching to the island's fjord mouths, while a third mid-shelf limit appears partially recorded. Work on dating the relict landscape of ancient ice cap advance and retreat is ongoing, but our preliminary age model suggests that South Georgia's history is unique from the Antarctic polar glacial record, and may be more similar to that of past ice caps on Patagonia. The glacial configurations revealed by these data will provide the basis of new

  5. 低纬西太平洋末次冰期以来海洋孢粉记录对海平面变化的不同响应%THE DIFFERENT RESPONSE OF MARINE POLLEN RECORDS TO THE SEA LEVEL CHANGE IN THE LOW LATITUDE WEST PACIFIC SINCE THE LAST GLACIAL PERIOD

    Institute of Scientific and Technical Information of China (English)

    边叶萍; 李家彪; 翦知湣; 初凤友; 翁成郁; Kuhnt Wolfgang

    2012-01-01

    between the sea-level change and the marine pollen record, mainly the mangrove pollen and fern spore record. In this study, the palynological analysis of two marine core, MD06 -3075 (06. 4762°N,125. 8322°E;1878m water depth,30. 76m in length) in the southern Philippines and MD98-2178 (03. 6200°N,118. 7000°E; 1984m water depth, 35.6m in length) in the north East Borneo, the detailed oxygen isotope records, and other marine pollen records in the West Pacific, provide the regional vegetation and climate history since the Last Glacial. Based on AMS C dating and plankton foraminifera oxygen isotope record, the core MD06-3075 covers last 52ka,and the core MD98-2178 covers last 92ka( pollen analysis includes records of the last 77 ka) . The palynological record shows low representation of mangrove pollen and fern spore during the glacial period,indicating lower sea level and drier climate condition during the glacial period than the deglacial period, especially the Last Glacial Maximum. However,through the comparison of marine pollen records in the West Pacific area,there are some different pollen records in the southern South China Sea. It shows significantly high value of mangrove pollen from a marine core in the slope area and fern spore from marine core in the Sunda Shelf. These differences may be caused by the drop of sea level change,which lead to the explosion of the Sunda Shelf and the changes of vegetation distribution and distance between vegetation source and deposition point. Therefore, the interpretation of marine pollen data should be combing with the multiple sedimentary index and the geophysical survey record, which would raise the recognition of the influence of sea level change and the corresponding sedimentary environment evolution on marine pollen transportation and deposition, enhancing the extraction of the paleoclimate and paleoenviroment information from the marine palynology.

  6. Enhanced carbon pump inferred from relaxation of nutrient limitation in the glacial ocean.

    Science.gov (United States)

    Pichevin, L E; Reynolds, B C; Ganeshram, R S; Cacho, I; Pena, L; Keefe, K; Ellam, R M

    2009-06-25

    The modern Eastern Equatorial Pacific (EEP) Ocean is a large oceanic source of carbon to the atmosphere. Primary productivity over large areas of the EEP is limited by silicic acid and iron availability, and because of this constraint the organic carbon export to the deep ocean is unable to compensate for the outgassing of carbon dioxide that occurs through upwelling of deep waters. It has been suggested that the delivery of dust-borne iron to the glacial ocean could have increased primary productivity and enhanced deep-sea carbon export in this region, lowering atmospheric carbon dioxide concentrations during glacial periods. Such a role for the EEP is supported by higher organic carbon burial rates documented in underlying glacial sediments, but lower opal accumulation rates cast doubts on the importance of the EEP as an oceanic region for significant glacial carbon dioxide drawdown. Here we present a new silicon isotope record that suggests the paradoxical decline in opal accumulation rate in the glacial EEP results from a decrease in the silicon to carbon uptake ratio of diatoms under conditions of increased iron availability from enhanced dust input. Consequently, our study supports the idea of an invigorated biological pump in this region during the last glacial period that could have contributed to glacial carbon dioxide drawdown. Additionally, using evidence from silicon and nitrogen isotope changes, we infer that, in contrast to the modern situation, the biological productivity in this region is not constrained by the availability of iron, silicon and nitrogen during the glacial period. We hypothesize that an invigorated biological carbon dioxide pump constrained perhaps only by phosphorus limitation was a more common occurrence in low-latitude areas of the glacial ocean.

  7. A 33,000-year-old incipient dog from the Altai Mountains of Siberia: evidence of the earliest domestication disrupted by the Last Glacial Maximum.

    Directory of Open Access Journals (Sweden)

    Nikolai D Ovodov

    Full Text Available BACKGROUND: Virtually all well-documented remains of early domestic dog (Canis familiaris come from the late Glacial and early Holocene periods (ca. 14,000-9000 calendar years ago, cal BP, with few putative dogs found prior to the Last Glacial Maximum (LGM, ca. 26,500-19,000 cal BP. The dearth of pre-LGM dog-like canids and incomplete state of their preservation has until now prevented an understanding of the morphological features of transitional forms between wild wolves and domesticated dogs in temporal perspective. METHODOLOGY/PRINCIPAL FINDING: We describe the well-preserved remains of a dog-like canid from the Razboinichya Cave (Altai Mountains of southern Siberia. Because of the extraordinary preservation of the material, including skull, mandibles (both sides and teeth, it was possible to conduct a complete morphological description and comparison with representative examples of pre-LGM wild wolves, modern wolves, prehistoric domesticated dogs, and early dog-like canids, using morphological criteria to distinguish between wolves and dogs. It was found that the Razboinichya Cave individual is most similar to fully domesticated dogs from Greenland (about 1000 years old, and unlike ancient and modern wolves, and putative dogs from Eliseevichi I site in central Russia. Direct AMS radiocarbon dating of the skull and mandible of the Razboinichya canid conducted in three independent laboratories resulted in highly compatible ages, with average value of ca. 33,000 cal BP. CONCLUSIONS/SIGNIFICANCE: The Razboinichya Cave specimen appears to be an incipient dog that did not give rise to late Glacial-early Holocene lineages and probably represents wolf domestication disrupted by the climatic and cultural changes associated with the LGM. The two earliest incipient dogs from Western Europe (Goyet, Belguim and Siberia (Razboinichya, separated by thousands of kilometers, show that dog domestication was multiregional, and thus had no single place of

  8. Creative Ventures: Ancient Civilizations.

    Science.gov (United States)

    Stark, Rebecca

    The open-ended activities in this book are designed to extend the imagination and creativity of students and encourage students to examine their feelings and values about historic eras. Civilizations addressed include ancient Egypt, Greece, Rome, Mayan, Stonehenge, and Mesopotamia. The activities focus upon the cognitive and affective pupil…

  9. Ancient Egypt: Personal Perspectives.

    Science.gov (United States)

    Wolinski, Arelene

    This teacher resource book provides information on ancient Egypt via short essays, photographs, maps, charts, and drawings. Egyptian social and religious life, including writing, art, architecture, and even the practice of mummification, is conveniently summarized for the teacher or other practitioner in a series of one to three page articles with…

  10. Cloning Ancient Trees

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    west of Tiananmen Square in Beijing, in Zhongshan Park, there stand several ancient cypress trees, each more than 1,000 years old. Their leafy crowns are all more than 20 meters high, while four have trunks that are 6 meters in circumference. The most unique of these

  11. Ancient ports of Kalinga

    Digital Repository Service at National Institute of Oceanography (India)

    Tripati, S.

    The ancient Kingdom of Kalinga mentioned in the Hathigumpha inscription of Kharavela (1st century B.C.) extended from the mouths of the Ganges to the estuary of Godavari river on the East Coast. Ptolemy (100 A.D.) mentions that Paluru (District...

  12. Ancient deforestation revisited.

    Science.gov (United States)

    Hughes, J Donald

    2011-01-01

    The image of the classical Mediterranean environment of the Greeks and Romans had a formative influence on the art, literature, and historical perception of modern Europe and America. How closely does is this image congruent with the ancient environment as it in reality existed? In particular, how forested was the ancient Mediterranean world, was there deforestation, and if so, what were its effects? The consensus of historians, geographers, and other scholars from the mid-nineteenth century through the first three quarters of the twentieth century was that human activities had depleted the forests to a major extent and caused severe erosion. My research confirmed this general picture. Since then, revisionist historians have questioned these conclusions, maintaining instead that little environmental damage was done to forests and soils in ancient Greco-Roman times. In a reconsideration of the question, this paper looks at recent scientific work providing proxy evidence for the condition of forests at various times in ancient history. I look at three scientific methodologies, namely anthracology, palynology, and computer modeling. Each of these avenues of research offers support for the concept of forest change, both in abundance and species composition, and episodes of deforestation and erosion, and confirms my earlier work.

  13. Printing Ancient Terracotta Warriors

    Science.gov (United States)

    Gadecki, Victoria L.

    2010-01-01

    Standing in awe in Xian, China, at the Terra Cotta warrior archaeological site, the author thought of sharing this experience and excitement with her sixth-grade students. She decided to let her students carve patterns of the ancient soldiers to understand their place in Chinese history. They would make block prints and print multiple soldiers on…

  14. Glacial advances and ESR chronology of the Pochengzi Glaciation,Tianshan Mountains,China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Pochengzi Glaciation is a typical glaciation in Quaternary in the Tianshan Mountains. The glacial landforms comprise several integrated end moraines, like a fan spreading from the north to the south at the mouth of the Muzhaerte River valley and on the piedmont on the southeastern slope of the Tumur Peak, the largest center of modern glaciation in the Tianshan Mountains. The landforms recorded a complex history of the ancient glacier change and contained considerable information of the glacial landscape evolution, and dating these landforms helps us understand the temporal and spatial shifts of the past cryosphere in this valley and reconstruct the paleoenvironment in this region. Electron spin resonance (ESR) dating of the glacial tills in the upper stratum from a well-exposed section, end moraines, and associated outwashes was carried out using Ge centers in quartz grains, which are sensitive to the sunlight and grinding. The results could be divided into three clusters, 13.6–25.3, 39.5–40.4 and 64.2–71.7 ka. Based on the principle of geomorphology and stratigraphy and the available paleoen- vironmental data from northwestern China, the end moraines were determined to deposit in the Last Glaciation. The landforms and the three clusters of ages demonstrate that at least three large glacial advances occurred during the Pochengzi Glaciation, which are corresponding to marine oxygen isotope stage 4 (MIS4), MIS3b and MIS2. The landforms also indicate that the gla- ciers were compound valley glacier in MIS2 and MIS3b and piedmont glacier in MIS4, and the ancient Muzhaerte glacier were 94, 95 and 99 km at their maximum extensions in these three glacial advances.

  15. Ancient climate change, antifreeze, and the evolutionary diversification of Antarctic fishes.

    Science.gov (United States)

    Near, Thomas J; Dornburg, Alex; Kuhn, Kristen L; Eastman, Joseph T; Pennington, Jillian N; Patarnello, Tomaso; Zane, Lorenzo; Fernández, Daniel A; Jones, Christopher D

    2012-02-28

    The Southern Ocean around Antarctica is among the most rapidly warming regions on Earth, but has experienced episodic climate change during the past 40 million years. It remains unclear how ancient periods of climate change have shaped Antarctic biodiversity. The origin of antifreeze glycoproteins (AFGPs) in Antarctic notothenioid fishes has become a classic example of how the evolution of a key innovation in response to climate change can drive adaptive radiation. By using a time-calibrated molecular phylogeny of notothenioids and reconstructed paleoclimate, we demonstrate that the origin of AFGP occurred between 42 and 22 Ma, which includes a period of global cooling approximately 35 Ma. However, the most species-rich lineages diversified and evolved significant ecological differences at least 10 million years after the origin of AFGPs, during a second cooling event in the Late Miocene (11.6-5.3 Ma). This pattern indicates that AFGP was not the sole trigger of the notothenioid adaptive radiation. Instead, the bulk of the species richness and ecological diversity originated during the Late Miocene and into the Early Pliocene, a time coincident with the origin of polar conditions and increased ice activity in the Southern Ocean. Our results challenge the current understanding of the evolution of Antarctic notothenioids suggesting that the ecological opportunity that underlies this adaptive radiation is not linked to a single trait, but rather to a combination of freeze avoidance offered by AFGPs and subsequent exploitation of new habitats and open niches created by increased glacial and ice sheet activity.

  16. Inverse correlation between ancient winter and summer monsoons in East Asia?

    Institute of Scientific and Technical Information of China (English)

    ZHOU BoTao; ZHAO Ping

    2009-01-01

    There is a scientific debate on the relationship between ancient winter and summer monsoons in East Asia. Some scholars think that East Asian winter and summer monsoons are anti-correlated, and oth-ers think not. For this reason, this study is motivated to assess their linkage from the paleoclimate simulation perspective, through analyzing the Last Glacial Maximum (LGM) and mid-Holocene (MH) climate simulated by CCSM3 model. Compared to the present climate, the Aleutian low is found to be deepened and the East Asian winter monsoon (EAWM) is stronger during the LGM winter. The Pacific high in summer is noticed to be weakened and the East Asian summer monsoon (EASM) is weaker at the LGM. During the MH, the Aleutian low and the Asian high in winter are intensified, and the Asian low and the Pacific high in summer are enhanced, indicating that the EAWM and EASM are both stronger than today. Therefore, the EAWM is not always negatively correlated to the EASM. Their relationship may be different at different geological stages. It can be obtained at least from the numerical simulation results that the EAWM and the EASM is negatively correlated during the cooling period, while positively correlated during the warming period.

  17. Glacial lakes Buni and Jezerce: Albania

    OpenAIRE

    Milivojević Milovan; Kovačević-Majkić Jelena

    2005-01-01

    The paper presents glacial lakes and glacial relief forms at the foothill of the peak Maja Jezerce in Mt. Prokletije in Albania, near the border with Montenegro. The group of lakes Buni and Jezerce, which consists of six lakes and which genetically belongs to glacial-erosional lakes, is analyzed. Lakes are situated at the cirque bottom, between the moraines and limestone ridges. Except presented morphometric characteristics of lake basins, data about cirque are given, as well as the reconstru...

  18. [Anomalous pregnancies in ancient medicine].

    Science.gov (United States)

    Gazzaniga, Valentina

    2010-01-01

    In ancient Greek medicine female physiology is determined by a particular state of non-steady equilibrium, largely based on pregnancy and lactation, presented as the only balanced and healthy periods in women's life. Nonetheless, pregnancy can be also a pathological moment, in particular referring to specific alterations of its 'normal time' ('seven-months', 'eight-months' and 'ten-months' children). The article analyzes the well-known case of myle, an abnormal pregnancy developing in three and sometimes four years, non resolving in a normal delivery, but often in a dramatic haemorrhagic flux. The author compares Hippocratic and Aristotelic testimonies about myle and abnormal pregnancies with the evidence fournished by the historical-religious recent studies about Hera and her parthenogenetic, monstrous children.

  19. Glacial-Interglacial Atmospheric CO2 Change--The Glacial Burial Hypothesis

    Institute of Scientific and Technical Information of China (English)

    Ning ZENG

    2003-01-01

    Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to bethe missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, theadvancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer pe-riods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over twoglacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced byreconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacialmaximum to interglacial, resulting in a 60-Gt (about 30-ppmv) increase in the atmospheric CO2, with theremainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrastto previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial,continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The inputof light isotope enriched terrestrial carbon causes atmospheric 513C to drop by about 0.3% at deglaciation,followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowthon land. Together with other ocean based mechanisms such as change in ocean temperature, the glacialburial hypothesis may offer a full explanation of the observed 80 100-ppmv atmospheric CO2 change.

  20. Ancient human microbiomes.

    Science.gov (United States)

    Warinner, Christina; Speller, Camilla; Collins, Matthew J; Lewis, Cecil M

    2015-02-01

    Very recently, we discovered a vast new microbial self: the human microbiome. Our native microbiota interface with our biology and culture to influence our health, behavior, and quality of life, and yet we know very little about their origin, evolution, or ecology. With the advent of industrialization, globalization, and modern sanitation, it is intuitive that we have changed our relationship with microbes, but we have little information about the ancestral state of our microbiome, and we therefore lack a foundation for characterizing this change. High-throughput sequencing has opened up new opportunities in the field of paleomicrobiology, allowing us to investigate the evolution of the complex microbial ecologies that inhabit our bodies. By focusing on recent coprolite and dental calculus research, we explore how emerging research on ancient human microbiomes is changing the way we think about ancient disease and how archaeological studies can contribute to a medical understanding of health and nutrition today.

  1. Comets in ancient India

    CERN Document Server

    Gupta, Patrick Das

    2014-01-01

    The Indo-aryans of ancient India observed stars and constellations for ascertaining auspicious times for sacrificial rites ordained by vedas. It is but natural that they would have recounted in the vedic texts about comets. In Rigveda ($\\sim $ 1700 - 1500 BC) and Atharvaveda ($\\sim $ 1150 BC), there are references to dhumaketus and ketus, which stand for comets in Sanskrit. Varahamihira in 550 AD and Ballala Sena ($\\sim $ 1100 - 1200 AD) have described a large number of comets recorded by ancient seers such as Parashara, Vriddha Garga, Narada, Garga, etc. In this article, I conjecture that an episode narrated in Mahabharata of a radiant king, Nahusha, ruling the heavens, and later turning into a serpent after he had kicked the seer Agastya (also the star Canopus), is a mythological retelling of a cometary event.

  2. Glacial effects limiting mountain height.

    Science.gov (United States)

    Egholm, D L; Nielsen, S B; Pedersen, V K; Lesemann, J-E

    2009-08-13

    The height of mountain ranges reflects the balance between tectonic rock uplift, crustal strength and surface denudation. Tectonic deformation and surface denudation are interdependent, however, and feedback mechanisms-in particular, the potential link to climate-are subjects of intense debate. Spatial variations in fluvial denudation rate caused by precipitation gradients are known to provide first-order controls on mountain range width, crustal deformation rates and rock uplift. Moreover, limits to crustal strength are thought to constrain the maximum elevation of large continental plateaus, such as those in Tibet and the central Andes. There are indications that the general height of mountain ranges is also directly influenced by the extent of glaciation through an efficient denudation mechanism known as the glacial buzzsaw. Here we use a global analysis of topography and show that variations in maximum mountain height correlate closely with climate-controlled gradients in snowline altitude for many high mountain ranges across orogenic ages and tectonic styles. With the aid of a numerical model, we further demonstrate how a combination of erosional destruction of topography above the snowline by glacier-sliding and commensurate isostatic landscape uplift caused by erosional unloading can explain observations of maximum mountain height by driving elevations towards an altitude window just below the snowline. The model thereby self-consistently produces the hypsometric signature of the glacial buzzsaw, and suggests that differences in the height of mountain ranges mainly reflect variations in local climate rather than tectonic forces.

  3. Ambrosia of Ancients

    Institute of Scientific and Technical Information of China (English)

    HUOJIANYING

    2004-01-01

    IN 196 B.C. a Chinese philosopher observedto his ruler: "A lord's to ppriority is the welfare of his subjects; to the peopie, eating is foremost." Chinese ancients perceived clearly the essentiality of grain cultivation to the survival of the population and country as a whole. This is apparent in the premillennial term for "country" -sheji literally translated as god of land and grain.

  4. Chemistry Progress and Civilization in Ancient China

    Institute of Scientific and Technical Information of China (English)

    JIANG Yu-Qian; RUAN Shu-Xiang; TANG Shan; SHUAI Zhi-Gang

    2011-01-01

    @@ During the 6,000 years of Chinese civilization, chemistry has played an essential role.The bronzed chime bells of the Warring States Period (475-221 BC) unearthed in Hubei Province shows not only the excellence in musical instruments in ancient China, but also the technological advances in metallurgy.Chinese alchemy was not originated from the quest to turn common metals to gold, instead, it was for searching medicines for longevity of human beings, mostly practised by Taoists.

  5. Ancient Human Parasites in Ethnic Chinese Populations

    Science.gov (United States)

    Yeh, Hui-Yuan; Mitchell, Piers D.

    2016-01-01

    Whilst archaeological evidence for many aspects of life in ancient China is well studied, there has been much less interest in ancient infectious diseases, such as intestinal parasites in past Chinese populations. Here, we bring together evidence from mummies, ancient latrines, and pelvic soil from burials, dating from the Neolithic Period to the Qing Dynasty, in order to better understand the health of the past inhabitants of China and the diseases endemic in the region. Seven species of intestinal parasite have been identified, namely roundworm, whipworm, Chinese liver fluke, oriental schistosome, pinworm, Taenia sp. tapeworm, and the intestinal fluke Fasciolopsis buski. It was found that in the past, roundworm, whipworm, and Chinese liver fluke appear to have been much more common than the other species. While roundworm and whipworm remained common into the late 20th century, Chinese liver fluke seems to have undergone a marked decline in its prevalence over time. The iconic transport route known as the Silk Road has been shown to have acted as a vector for the transmission of ancient diseases, highlighted by the discovery of Chinese liver fluke in a 2,000 year-old relay station in northwest China, 1,500 km outside its endemic range. PMID:27853113

  6. Defining Astrology in Ancient and Classical History

    Science.gov (United States)

    Campion, Nicholas

    2015-05-01

    Astrology in the ancient and classical worlds can be partly defined by its role, and partly by the way in which scholars spoke about it. The problem is complicated by the fact that the word is Greek - it has no Babylonian or Egyptian cognates - and even in Greece it was interchangeable with its cousin, 'astronomy'. Yet if we are to understand the role of the sky, stars and planets in culture, debates about the nature of ancient astrology, by both classical and modern scholars, must be taken into account. This talk will consider modern scholars' typologies of ancient astrology, together with ancient debates from Cicero in the 1st century BC, to Plotinus (204/5-270 AD) and Isidore of Seville (c. 560 - 4 April 636). It will consider the implications for our understanding of astronomy's role in culture, and conclude that in the classical period astrology may be best understood through its diversity and allegiance to competing philosophies, and that its functions were therefore similarly varied.

  7. Genomic correlates of atherosclerosis in ancient humans.

    Science.gov (United States)

    Zink, Albert; Wann, L Samuel; Thompson, Randall C; Keller, Andreas; Maixner, Frank; Allam, Adel H; Finch, Caleb E; Frohlich, Bruno; Kaplan, Hillard; Lombardi, Guido P; Sutherland, M Linda; Sutherland, James D; Watson, Lucia; Cox, Samantha L; Miyamoto, Michael I; Narula, Jagat; Stewart, Alexandre F R; Thomas, Gregory S; Krause, Johannes

    2014-06-01

    Paleogenetics offers a unique opportunity to study human evolution, population dynamics, and disease evolution in situ. Although histologic and computed x-ray tomographic investigations of ancient mummies have clearly shown that atherosclerosis has been present in humans for more than 5,000 years, limited data are available on the presence of genetic predisposition for cardiovascular disease in ancient human populations. In a previous whole-genome study of the Tyrolean Iceman, a 5,300-year-old glacier mummy from the Alps, an increased risk for coronary heart disease was detected. The Iceman's genome revealed several single nucleotide polymorphisms that are linked with cardiovascular disease in genome-wide association studies. Future genetic studies of ancient humans from various geographic origins and time periods have the potential to provide more insights into the presence and possible changes of genetic risk factors in our ancestors. The study of ancient humans and a better understanding of the interaction between environmental and genetic influences on the development of heart diseases may lead to a more effective prevention and treatment of the most common cause of death in the modern world.

  8. Polar Climate Connections of the Last Glacial Period

    Science.gov (United States)

    Yang, X.; Rial, J. A.

    2015-12-01

    Ever since the cross-core chronology became available, the connection between the Earth's polar regions - or the lack of such [Wunsch, 2003; 2006] - has been an on-going debate in the paleoclimate community. While the inverse relationship inferred from the bipolar seesaw model [Crowley, 1992] could not account for the difference in signal shape of the polar records, integration/differentiation (I/D) has been proposed as the linkage between them [Schmittner et al., 2003; Huybers, 2004; Roe and Steig, 2004; Schmittner et al., 2004]. Stoker and Johnsen [2003] have proposed a revised (thermal) bipolar seesaw model (TBS), demonstrating that the climate record from Antarctic is that of the Greenland convolved with an exponential decaying function, which represents the heat reservoir of the Southern Ocean. More recently, Rial [2012] has proposed phase synchronization (PS) as the polar climate connection from which polar climate records can be treated approximately as a Hilbert transform pair. All three models (I/D, TBS, and PS) have been used to reconstruct past climate of the north from the longer climate record of the south [Siddall et al., 2006; Barker et al., 2011; Oh et al., 2014]. However, no comparison has been made to test and analyze these models against one another for their performance and stabilities. Here we investigated the aforementioned models with polar climate data on the recent AICC2012 chronology to derive the similarities and differences among them in both time and frequency domains. Most importantly we discussed how such differences translate to the discrepancies in reconstructions of the northern climate and possible physical mechanism(s) of connection each model limits and allows. ReferencesBarker et al., 2011, Science, 334(6054), 347-351. Crowley, 1992, Paleoceanography, 7(4), 489-497. Huybers, 2004, QSR, 23(1-2), 207-210. Oh et al., 2014, QSR, 83, 129-142. Rial, 2012, Am J Sci, 312(4), 417-448. Roe & Steig, 2004, Journal of Climate, 17(10), 1929-1944. Schmittner et al., 2003, QSR, 22(5-7), 659-671. Schmittner et al., 2004, QSR, 23(1-2), 210-212. Siddall et al., 2006, QSR, 25(23), 3185-3197. Stocker & Johnsen, 2003, Paleoceanography, 18(4), 1087. Wunsch, 2003, QSR, 22(15-17), 1631-1646. Wunsch, 2006, Quaternary Research, 65(2), 191-203.

  9. 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

  10. An interhemispheric mechanism for glacial abrupt climate change

    Science.gov (United States)

    Banderas, Rubén; Alvarez-Solas, Jorge; Robinson, Alexander; Montoya, Marisa

    2015-05-01

    The last glacial period was punctuated by abrupt climate changes that are widely considered to result from millennial-scale variability of the Atlantic meridional overturning circulation (AMOC). However, the origin of these AMOC reorganizations remains poorly understood. The climatic connection between both hemispheres indicated by proxies suggests that the Southern Ocean (SO) could regulate this variability through changes in winds and atmospheric CO concentration. Here, we investigate this hypothesis using a coupled climate model forced by prescribed CO and SO wind-stress variations. We find that the AMOC exhibits an oscillatory behavior between weak and strong circulation regimes which is ultimately caused by changes in the meridional density gradient of the Atlantic Ocean. The evolution of the simulated climatic patterns matches the amplitude and timing of the largest events that occurred during the last glacial period and their widespread climatic impacts. Our results suggest the existence of an internal interhemispheric oscillation mediated by the bipolar seesaw that could promote glacial abrupt climate changes through variations in atmospheric CO levels, the strength of the SO winds and AMOC reorganizations, and provide an explanation for the pervasive Antarctic-like climate signal found in proxy records worldwide.

  11. Suicide in ancient Greece.

    Science.gov (United States)

    Laios, K; Tsoukalas, G; Kontaxaki, M-I; Karamanou, M; Androutsos, G

    2014-01-01

    The theme of suicide appears several times in ancient Greek literature. However, each such reference acquires special significance depending on the field from which it originates. Most of the information found in mythology, but the suicide in a mythological tale, although in terms of motivation and mental situation of heroes may be in imitation of similar incidents of real life, in fact is linked with the principles of the ancient Greek religion. In ancient drama and mainly in tragedies suicide conduces to the tragic hypostasis of the heroes and to the evolution of the plot and also is a tool in order to be presented the ideas of poets for the relations of the gods, the relation among gods and men and the relation among the men. In ancient Greek philosophy there were the deniers of suicide, who were more concerned about the impact of suicide on society and also these who accepted it, recognizing the right of the individual to put an end to his life, in order to avoid personal misfortunes. Real suicides will be found mostly from historical sources, but most of them concern leading figures of the ancient world. Closer to the problem of suicide in the everyday life of antiquity are ancient Greek medicines, who studied the phenomenon more general without references to specific incidents. Doctors did not approve in principal the suicide and dealt with it as insane behavior in the development of the mental diseases, of melancholia and mania. They considered that the discrepancy of humors in the organ of logic in the human body will cause malfunction, which will lead to the absurdity and consequently to suicide, either due to excessive concentration of black bile in melancholia or due to yellow bile in mania. They believed that greater risk to commit suicide had women, young people and the elderly. As therapy they used the drugs of their time with the intention to induce calm and repression in the ill person, therefore they mainly used mandragora. In general, we would say

  12. How can a glacial inception be predicted?

    CERN Document Server

    Crucifix, Michel

    2011-01-01

    The Early Anthropogenic Hypothesis considers that greenhouse gas concentrations should have declined during the Holocene in absence of humankind activity, leading to glacial inception around the present. It partly relies on the fact that present levels of northern summer incoming solar radiation are close to those that, in the past, preceded a glacial inception phenomenon, associated to declines in greenhouse gas concentrations. However, experiments with various numerical models of glacial cycles show that next glacial inception may still be delayed by several ten thousands of years, even with the assumption of greenhouse gas concentration declines during the Holocene. Furthermore, as we show here, conceptual models designed to capture the gross dynamics of the climate system as a whole suggest also that small disturbances may sometimes cause substantial delays in glacial events, causing a fair level of unpredictability on ice age dynamics. This suggests the need of a validated mathematical description of the...

  13. A mechanism for dust-induced destabilization of glacial climates

    Directory of Open Access Journals (Sweden)

    B. F. Farrell

    2012-05-01

    Full Text Available Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate qualitatively glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle.

  14. A mechanism for dust-induced destabilization of glacial climates

    Directory of Open Access Journals (Sweden)

    B. F. Farrell

    2012-12-01

    Full Text Available Abrupt transitions between cold/dry stadial and warm/wet interstadial states occurred during glacial periods in the absence of any known external forcing. The climate record preserved in polar glaciers, mountain glaciers, and widespread cave deposits reveals that these events were global in extent with temporal distribution implying an underlying memoryless process with millennial time scale. Here a theory is advanced implicating feedback between atmospheric dust and the hydrological cycle in producing these abrupt transitions. Calculations are performed using a radiative-convective model that includes the interaction of aerosols with radiation to reveal the mechanism of this dust/precipitation interaction feedback process and a Langevin equation is used to illustrate glacial climate destabilization by this mechanism. This theory explains the observed abrupt, bimodal, and memoryless nature of these transitions as well as their intrinsic connection with the hydrological cycle.

  15. Glacial cycles drive variations in the production of oceanic crust.

    Science.gov (United States)

    Crowley, John W; Katz, Richard F; Huybers, Peter; Langmuir, Charles H; Park, Sung-Hyun

    2015-03-13

    Glacial cycles redistribute water between oceans and continents, causing pressure changes in the upper mantle, with consequences for the melting of Earth's interior. Using Plio-Pleistocene sea-level variations as a forcing function, theoretical models of mid-ocean ridge dynamics that include melt transport predict temporal variations in crustal thickness of hundreds of meters. New bathymetry from the Australian-Antarctic ridge shows statistically significant spectral energy near the Milankovitch periods of 23, 41, and 100 thousand years, which is consistent with model predictions. These results suggest that abyssal hills, one of the most common bathymetric features on Earth, record the magmatic response to changes in sea level. The models and data support a link between glacial cycles at the surface and mantle melting at depth, recorded in the bathymetric fabric of the sea floor.

  16. Bifurcation structure and noise assisted transitions in the Pleistocene glacial cycles

    DEFF Research Database (Denmark)

    Ditlevsen, Peter

    2009-01-01

    The glacial cycles are attributed to the climatic response of the orbital changes in the irradiance to the Earth. These changes in the forcing are too small to explain the observed climate variations as simple linear responses. Nonlinear amplifications of the orbital forcing are necessary...... to account for the glacial cycles. Here an empirical model of the nonlinear response is presented. From the model it is possible to assess the role of stochastic noise in comparison to the deterministic orbital forcing of the ice ages. The model is based on the bifurcation structure derived from the climate...... glacial and interglacial climate are assisted by internal stochastic noise in the period prior to the last five glacial cycles, while the last five cycles are deterministic responses to the orbital forcing....

  17. Glacial Features (Point) - Quad 186 (HAMPTON, NH-MA)

    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,...

  18. Glacial Features (Point) - Quad 167 (MT. PAWTUCKAWAY, 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,...

  19. Glacial Features (Point) - Quad 202 (NEWBURYPORT EAST, MA-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. Glacial Features (Point) - Quad 185 (EXETER, NH-MA)

    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,...

  1. Glacial Features (Point) - Quad 170 (PORTSMOUTH, NH-ME)

    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,...

  2. Glacial Features (Point) - Quad 156 (DOVER EAST, NH-ME)

    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,...

  3. Glacial Features (Point) - Quad 155 (DOVER WEST, 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,...

  4. Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability.

    Science.gov (United States)

    Hu, Aixue; Meehl, Gerald A; Han, Weiqing; Timmermann, Axel; Otto-Bliesner, Bette; Liu, Zhengyu; Washington, Warren M; Large, William; Abe-Ouchi, Ayako; Kimoto, Masahide; Lambeck, Kurt; Wu, Bingyi

    2012-04-24

    Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80-11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the ocean conveyor belt circulation to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open.

  5. Japan: The Modernization of an Ancient Culture. Series on Public Issues No. 3.

    Science.gov (United States)

    Wolken, Lawrence C.

    This booklet, one of a series of booklets intended to apply economic principles to major social and political issues of the day, traces the modernization of the ancient culture of Japan. Four major areas are covered: (1) "An Ancient Culture" covers the period from the first settling of Japan through the Heian period, the medieval ages, the Meiji…

  6. Dance in Ancient Greek Culture

    OpenAIRE

    Spalva, Rita

    2015-01-01

    The greatness and harmony of ancient Greece has had an impact upon the development of the Western European culture to this day. The ancient Greek culture has influenced contemporary literature genres and systems of philosophy, principles of architecture, sculpture and drama and has formed basis for such sciences as astronomy and mathematics. The art of ancient Greece with its penchant for beauty and clarity has been the example of the humanity’s search for an aesthetic ideal. Despite only bei...

  7. Mathematics in ancient Greece

    CERN Document Server

    Dantzig, Tobias

    2006-01-01

    More than a history of mathematics, this lively book traces mathematical ideas and processes to their sources, stressing the methods used by the masters of the ancient world. Author Tobias Dantzig portrays the human story behind mathematics, showing how flashes of insight in the minds of certain gifted individuals helped mathematics take enormous forward strides. Dantzig demonstrates how the Greeks organized their precursors' melange of geometric maxims into an elegantly abstract deductive system. He also explains the ways in which some of the famous mathematical brainteasers of antiquity led

  8. Ancient concrete works

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    It is commonly believed that the ancient Romans were the first to create and use concrete. This is not true, as we can easily learn from the Latin literature itself. For sure, Romans were able to prepare high-quality hydraulic cements, comparable with the modern Portland cements. In this paper, we will see that the use of concrete is quite older, ranging back to the Homeric times. For instance, it was used for the floors of some courts and galleries of the Mycenaean palace at Tiryns

  9. Climate and Ancient Societies

    DEFF Research Database (Denmark)

    Climate, and human responses to it, have a strongly interconnected relationship. This when climate change occurs, the result of either natural or human causes, societies should react and adapt to these. But do they? If so, what is the nature of that change, and are the responses positive...... or negative for the long-term survival of social groups? In this volume, scholars from diverse disciplines including archaeology, geology and climate sciences explore scientific and material evidence for climate changes in the past, their causes, their effects on ancient societies and how those societies...

  10. Theory-of-mind reasoning in Ancient China

    NARCIS (Netherlands)

    van Emde Boas, P.

    2014-01-01

    Ancient Chinese literature on strategic theory goes back to ideas proposed almost 3000 years ago, but which were first written down during the late Spring and Autumn period and the Warring States period (around 500 BC). The most famous work is the Art of War from Sun Tzu. While Sun Tzu extensively r

  11. 10Be cosmic-ray exposure dating of moraines and rock avalanches in the Upper Romanche valley (French Alps): Evidence of two glacial advances during the Late Glacial/Holocene transition

    Science.gov (United States)

    Chenet, Marie; Brunstein, Daniel; Jomelli, Vincent; Roussel, Erwan; Rinterknecht, Vincent; Mokadem, Fatima; Biette, Melody; Robert, Vincent; Léanni, Laëtitia

    2016-09-01

    Cosmic-ray exposure (CRE) dating of moraines allow glacier fluctuations and past climate change reconstructions. In the French Alps, there is a lack of moraine dating for the Late Glacial/Holocene transition period. Here we present a chronology of glacier advances in the Upper Romanche valley (French Alps - Massif des Ecrins) based on 10Be CRE dating. CRE ages of moraines of 13.0 ± 1.1 ka and 12.4 ± 1.5 ka provide evidence for two stages of glacial advance or standstill at the end of the Late Glacial. The CRE dating of a rock avalanche deposit at 12.2 ± 1.5 ka is attributed to post-glacial debuttressing and reveals rapid deglaciation at the end of the Late Glacial. A CRE age of 7.1 ± 0.7 ka of a second mass-wasting, whose triggering factor is unidentified so far, indicates that up to an altitude of 2300 m a.s.l., the valley was ice-free as of ∼7 kyr at the latest. The re-evaluation of 21 moraine 10Be CRE ages from nine glacial valleys across the Alps shows multiple glacial advances occurring at the Late Glacial/Holocene transition. These results lead to a re-evaluation of the importance of cooling events during the Allerød and the Younger Dryas in the Alps.

  12. Exploring Ancient Skies A Survey of Ancient and Cultural Astronomy

    CERN Document Server

    Kelley, David H

    2011-01-01

    Exploring Ancient Skies brings together the methods of archaeology and the insights of modern astronomy to explore the science of astronomy as it was practiced in various cultures prior to the invention of the telescope. The book reviews an enormous and growing body of literature on the cultures of the ancient Mediterranean, the Far East, and the New World (particularly Mesoamerica), putting the ancient astronomical materials into their archaeological and cultural contexts. The authors begin with an overview of the field and proceed to essential aspects of naked-eye astronomy, followed by an examination of specific cultures. The book concludes by taking into account the purposes of ancient astronomy: astrology, navigation, calendar regulation, and (not least) the understanding of our place and role in the universe. Skies are recreated to display critical events as they would have appeared to ancient observers—events such as the supernova of 1054 A.D., the "lion horoscope," and the Star of Bethlehem. Explori...

  13. Uncertainty in Greenland glacial isostatic adjustment (Invited)

    Science.gov (United States)

    Milne, G. A.; Lecavalier, B.; Kjeldsen, K. K.; Kjaer, K.; Wolstencroft, M.; Wake, L. M.; Simpson, M. J.; Long, A. J.; Woodroffe, S.; Korsgaard, N. J.; Bjork, A. A.; Khan, S. A.

    2013-12-01

    It is well known that the interpretation of geodetic data in Greenland to constrain recent ice mass changes requires knowledge of isostatic land motion associated with past changes in the ice sheet. In this talk we will consider a variety of factors that limit how well the signal due to past mass changes (commonly referred to as glacial isostatic adjustment (GIA)) can be defined. Predictions based on a new model of Greenland GIA will be shown. Using these predictions as a reference, we will consider the influence of plausible variations in some key aspects of both the Earth and ice load components of the GIA model on predictions of land motion and gravity changes. The sensitivity of model output to plausible variations in both depth-dependent and lateral viscosity structure will be considered. With respect to the ice model, we will compare the relative contributions of loading during key periods of the ice history with a focus on the past few thousand years. In particular, we will show predictions of contemporary land motion and gravity changes due to loading changes following the Little Ice Age computed using a new reconstruction of ice thickness changes based largely on empirical data. A primary contribution of this work will be the identification of dominant sources of uncertainty in current models of Greenland GIA and the regions most significantly affected by this uncertainty.

  14. AMS radiocarbon dating of ancient Japanese sutras

    CERN Document Server

    Oda, H; Nakamura, T; Fujita, K

    2000-01-01

    Radiocarbon ages of ancient Japanese sutras whose historical ages were known paleographically were measured by means of accelerator mass spectrometry (AMS). Calibrated radiocarbon ages of five samples were consistent with the corresponding historical ages; the 'old wood effect' is negligible for ancient Japanese sutras. Japanese paper has been made from fresh branches grown within a few years and the interval from trimming off the branches to writing sutra on the paper is within one year. The good agreement between the calibrated radiocarbon ages and the historical ages is supported by such characteristics of Japanese paper. It is indicated in this study that Japanese sutra is a suitable sample for radiocarbon dating in the historic period because of little gap by 'old wood effect'.

  15. Putative ancient microorganisms from amber nuggets.

    Science.gov (United States)

    Veiga-Crespo, Patricia; Blasco, Lucía; Poza, Margarita; Villa, Tomás G

    2007-06-01

    Evolutionary microbiology studies based on the isolation of ancient DNA and/or microbial samples are scarce due to the difficulty of finding well preserved biological specimens. However, amber is a fossil resin with natural preserving properties for microbial cells and DNA. The visualization by transmission electron microscopy of different microorganism-like specimens found in amber nuggets from both the Miocene and the Cretaceous periods was accompanied by studies of ancient DNA obtained from the nuggets. After the design of specific primers based on the present sequences of both genes in Saccharomyces cerevisiae, the ancestral AGP2 sequence from the Miocene, as well as the 18S rRNA from the Cretaceous, were amplified.

  16. Rangifer and man: An ancient relationship

    Directory of Open Access Journals (Sweden)

    Bryan Gordon

    2003-04-01

    Full Text Available A long-term relationship between Rangifer and humans is documented in three case studies: the Canadian Barrenlands (8000 years ago to Historic period, Ice-Age France (11 000-19 000 years ago and Mesolithic Russia (7000¬10 000 years ago. Ancient human and herd migration occurred in all areas, based upon Rangifer remains and seasonal variations in tools along reconstructed migration routes, with few if any hunting camps outside the routes. An April peak of ancient human births is inferred from the historic record where we see births occurring nine months after peak nutritional states in herds and people. The origin of reindeer domestication and breeding in Eurasia is discussed.

  17. Massive remobilization of permafrost carbon during post-glacial warming

    Science.gov (United States)

    Tesi, T.; Muschitiello, F.; Smittenberg, R. H.; Jakobsson, M.; Vonk, J. E.; Hill, P.; Andersson, A.; Kirchner, N.; Noormets, R.; Dudarev, O.; Semiletov, I.; Gustafsson, Ö.

    2016-11-01

    Recent hypotheses, based on atmospheric records and models, suggest that permafrost carbon (PF-C) accumulated during the last glaciation may have been an important source for the atmospheric CO2 rise during post-glacial warming. However, direct physical indications for such PF-C release have so far been absent. Here we use the Laptev Sea (Arctic Ocean) as an archive to investigate PF-C destabilization during the last glacial-interglacial period. Our results show evidence for massive supply of PF-C from Siberian soils as a result of severe active layer deepening in response to the warming. Thawing of PF-C must also have brought about an enhanced organic matter respiration and, thus, these findings suggest that PF-C may indeed have been an important source of CO2 across the extensive permafrost domain. The results challenge current paradigms on the post-glacial CO2 rise and, at the same time, serve as a harbinger for possible consequences of the present-day warming of PF-C soils.

  18. Record of glacial Lake Missoula floods in glacial Lake Columbia, Washington

    Science.gov (United States)

    Hanson, Michelle A.; Clague, John J.

    2016-02-01

    During the last glaciation (marine oxygen isotope stage 2), outburst floods from glacial Lake Missoula deposited diagnostic sediments within glacial Lake Columbia. Two dominant outburst flood lithofacies are present within glacial Lake Columbia deposits: a flood expansion bar facies and a finer-grained hyperpycnite facies. We conclude that the flood sediments have a glacial Lake Missoula source because: (1) current indicators indicate westward flow through the lake, and upvalley flow followed by downvalley flow in tributary valleys; (2) no flood sediments are found north of a certain point; (3) there is a dominance of Belt-Purcell Supergroup clasts in a flood expansion bar; and (4) some of the finer-grained beds have a pink colour, reflective of glacial Lake Missoula lake-bottom sediments. A new radiocarbon age of 13,400 ± 100 14C BP on plant detritus found below 37 flood beds helps constrain the timing of outburst flooding from glacial Lake Missoula.

  19. Ancient and modern women in the "Woman's World".

    Science.gov (United States)

    Hurst, Isobel

    2009-01-01

    Under the editorship of Oscar Wilde, the "Woman's World" exemplified the popular dissemination of Hellenism through periodical culture. Addressing topics such as marriage, politics, and education in relation to the lives of women in the ancient world, the magazine offered an unfamiliar version of the reception of ancient Greece and Rome in late-Victorian aestheticism, one that was accessible to a wide readership because it was often based on images rather than texts. The classical scholar Jane Ellen Harrison addressed herself to this audience of women readers, discussing the similarities between modern collegiate life and the "woman's world" that enabled Sappho to flourish in ancient Greece. The "Woman's World" thus questions gender stereotypes by juxtaposing ancient and modern women, implicitly endorsing varied models of womanhood.

  20. Ancestry of modern Europeans: contributions of ancient DNA.

    Science.gov (United States)

    Lacan, Marie; Keyser, Christine; Crubézy, Eric; Ludes, Bertrand

    2013-07-01

    Understanding the peopling history of Europe is crucial to comprehend the origins of modern populations. Of course, the analysis of current genetic data offers several explanations about human migration patterns which occurred on this continent, but it fails to explain precisely the impact of each demographic event. In this context, direct access to the DNA of ancient specimens allows the overcoming of recent demographic phenomena, which probably highly modified the constitution of the current European gene pool. In recent years, several DNA studies have been successfully conducted from ancient human remains thanks to the improvement of molecular techniques. They have brought new fundamental information on the peopling of Europe and allowed us to refine our understanding of European prehistory. In this review, we will detail all the ancient DNA studies performed to date on ancient European DNA from the Middle Paleolithic to the beginning of the protohistoric period.

  1. Identifying the Practice of Tattooing in Ancient Egypt and Nubia

    Directory of Open Access Journals (Sweden)

    Geoffrey J. Tassie

    2003-11-01

    Full Text Available Tattooing was practised by many ancient societies, including the ancient Egyptians and Nubians. Egypt, for example, boasts iconographic and physical evidence for tattooing for a period spanning at least 4000 years – the longest known history of tattooing in the world. The second oldest physical evidence for tattooing worldwide was recovered from Middle Kingdom contexts in Egypt and C-Group contexts in Nubia (the Hanslabjoch ice man being the oldest. It has been suggested that tattooing was also practised in the Predynastic period as evidenced by figurines with geometric designs, however, no physical evidence for tattooing has yet been found for this early period. Strangely there is almost no mention of tattooing in ancient Egyptian written records. Historical and ethnographic records indicate that tattooing was also practised much more recently in the Coptic, Islamic and modern eras. Unlike many past societies, tattooing in Egypt appears to have been a custom practised almost exclusively on women. Tattooing tools have not yet been positively identified from ancient Egypt. Ethnographic sources suggest that bundles of metal rods were used in Egypt’s more recent history. This paper discusses physical and iconographic evidence for tattooing in ancient Egypt and investigates whether five copper rods found at Kafr Hassan Dawood, a Predynastic to Early Dynastic site in the East Delta, could be physical evidence for tattooing during this early period.

  2. The Arctic as a trigger for glacial terminations

    Energy Technology Data Exchange (ETDEWEB)

    Martinson, D.G.; Pitman, W.C. III [Lamont-Doherty Earth Observatory and Department of Earth and Environmental Sciences, Columbia University, 61 Route 9W, Palisades, NY 10964 (United States)

    2007-02-15

    We propose a hypothesis to explain the very abrupt terminations that end most of the glacial episodes. During the last glaciation, the buildup and southerly expansion of large continental ice-sheets in the Northern Hemisphere and extensive cover of sea ice in the N. Pacific and the N. Atlantic imposed a much more zonal climatic circulation system than exists today. We hypothesize that this, in combination with the frigid (dry) polar air led to a significant decrease in freshwater runoff into the Arctic Ocean. In addition the freshwater contribution of the fresher Pacific water was completely eliminated by the emergence of the Bering Strait (sill depth 50 m). As the Arctic freshwater input was depleted, regions of the Arctic Ocean lost surface stability and eventually overturned, bringing warmer deep water to the surface where it melted the overlying sea ice. This upwelled water was quickly cooled and sank as newly formed deep water. For sustained overturn events, such as might have occurred during the peak of very large glacial periods (i.e. the last glacial maximum), the voluminous deep water formed would eventually overflow into the Nordic Seas and North Atlantic necessitating an equally voluminous rate of return flow of warmer surface waters from the North Atlantic thus breaking down the Arctic's zonal isolation, melting the expansive NA sea ice cover and initiating oceanic heating of the atmosphere over the ice-sheets bordering the NA. We suggest that the combined effect of these overturn-induced events in concert with a Milankovitch warming cycle, was sufficient to drive the system to a termination. We elaborate on this proposed sequence of events, using the model for the formation of the Weddell Sea polynya as proposed by Martinson et al. (1981) and various, albeit sparse, data sets from the circum-Arctic region to apply and evaluate this hypothesis to the problem of glacial termination.

  3. Authenticity in ancient DNA studies

    DEFF Research Database (Denmark)

    Gilbert, M Thomas P; Willerslev, Eske

    2006-01-01

    Ancient DNA studies represent a powerful tool that can be used to obtain genetic insights into the past. However, despite the publication of large numbers of apparently successful ancient DNA studies, a number of problems exist with the field that are often ignored. Therefore, questions exist as ...

  4. Short length scale mantle heterogeneity beneath Iceland probed by glacial modulation of melting

    Science.gov (United States)

    Sims, Kenneth W. W.; Maclennan, John; Blichert-Toft, Janne; Mervine, Evelyn M.; Blusztajn, Jurek; Grönvold, Karl

    2013-10-01

    Glacial modulation of melting beneath Iceland provides a unique opportunity to better understand both the nature and length scale of mantle heterogeneity. At the end of the last glacial period, ∼13 000 yr BP, eruption rates were ∼20-100 times greater than in glacial or late postglacial times and geophysical modeling posits that rapid melting of the large ice sheet covering Iceland caused a transient increase in mantle decompression melting rates. Here we present the first time-series of Sr-Nd-Hf-Pb isotopic data for a full glacial cycle from a spatially confined region of basaltic volcanism in northern Iceland. Basalts and picrites erupted during the early postglacial burst of volcanic activity are systematically offset to more depleted isotopic compositions than those of lavas erupted during glacial or recent (Iceland is heterogeneous on small (glacial unloading indicates that the isotopic composition of mantle heterogeneities can be linked to their melting behavior. The present geochemical data can be accounted for by a melting model in which a lithologically heterogeneous mantle source contains an enriched component more fusible than its companion depleted component.

  5. A permafrost glacial hypothesis to explain atmospheric CO2 and the ice ages during the Pleistocene

    Directory of Open Access Journals (Sweden)

    R. Tarozo

    2010-10-01

    Full Text Available Over the past several 100 ka glacial-interglacial cycles, the concentration of atmospheric CO2 was closely coupled to global temperature, which indicates the importance of CO2 as a greenhouse gas. The reasons for changes in atmospheric CO2 have mainly been sought in the ocean, yet proxy evidence does not support the notion of increased oceanic carbon storage during glacials. Here we present results from the first permafrost loess sequence in Siberia spanning two glacial cycles (~240 ka, which reveal that permafrost soils repeatedly sequestered huge amounts of terrestrial carbon during glacial periods. This can be explained with permafrost favouring more intensive waterlogging conditions and better preservation of soil organic matter. Terrestrial carbon stored in permafrost soils was released upon warming and provided a powerful feedback mechanism for the glacial terminations. We outline a "permafrost glacial hypothesis" building on integrated annual insolation forcing, which readily explains the observed succession of the ice ages during the Pleistocene, including the mid-Pleistocene transition.

  6. Late-glacial atmospheric CO{sub 2} reconstructions from western Norway using fossil leaves

    Energy Technology Data Exchange (ETDEWEB)

    Birks, H.H.; Birks, H.J.B. [Sheffield Univ. (United Kingdom). Dept. of Animal and Plant Sciences; Beerling, D.J.; Woodward, F.I. [Bergen Univ. (Norway). Botanical Inst.

    1995-12-31

    Analyses of air bubbles trapped in Antarctic ice-cores have shown that atmospheric CO{sub 2} concentrations are 180-200 ppmv during glacial periods, and ca. 280 ppmv during interglacials, including the Holocene. The change from glacial to Holocene concentrations occurred steadily over ca. 5000 years, slightly lagging the temperature increase inferred from {delta}{sup 18}. Antarctic ice cores lack fine time resolution over the late-glacial/early Holocene period 12-9000 {sup 14}C yr BP, that includes the Younger Dryas cold oscillation. The stomatal density on leaves is inversely proportional to the concentration of atmospheric CO{sub 2}. A late glacial sequence at Kraakenes, western Norway, contains well-preserved Salix herbacea (dwarf willow) leaves, dated from 11700-9600 {sup 14}C yr BP. If the stomatal density is measured on the fossil leaves, a calibration derived from the relationship of stomatal density of modern material of the same species to known CO{sub 2} concentrations can be used to reconstruct CO{sub 2} concentrations of the past. Because of the decadal time-resolution available at Kraakenes through the late-glacial and early Holocene, a detailed record of CO{sub 2} concentrations can be reconstructed over this period, that will complement the ice core record. (author)

  7. Tamil merchant in ancient Mesopotamia.

    Directory of Open Access Journals (Sweden)

    Malliya Gounder Palanichamy

    Full Text Available Recent analyses of ancient Mesopotamian mitochondrial genomes have suggested a genetic link between the Indian subcontinent and Mesopotamian civilization. There is no consensus on the origin of the ancient Mesopotamians. They may be descendants of migrants, who founded regional Mesopotamian groups like that of Terqa or they may be merchants who were involved in trans Mesopotamia trade. To identify the Indian source population showing linkage to the ancient Mesopotamians, we screened a total of 15,751 mitochondrial DNAs (11,432 from the literature and 4,319 from this study representing all major populations of India. Our results although suggest that south India (Tamil Nadu and northeast India served as the source of the ancient Mesopotamian mtDNA gene pool, mtDNA of these ancient Mesopotamians probably contributed by Tamil merchants who were involved in the Indo-Roman trade.

  8. Tamil merchant in ancient Mesopotamia.

    Science.gov (United States)

    Palanichamy, Malliya Gounder; Mitra, Bikash; Debnath, Monojit; Agrawal, Suraksha; Chaudhuri, Tapas Kumar; Zhang, Ya-Ping

    2014-01-01

    Recent analyses of ancient Mesopotamian mitochondrial genomes have suggested a genetic link between the Indian subcontinent and Mesopotamian civilization. There is no consensus on the origin of the ancient Mesopotamians. They may be descendants of migrants, who founded regional Mesopotamian groups like that of Terqa or they may be merchants who were involved in trans Mesopotamia trade. To identify the Indian source population showing linkage to the ancient Mesopotamians, we screened a total of 15,751 mitochondrial DNAs (11,432 from the literature and 4,319 from this study) representing all major populations of India. Our results although suggest that south India (Tamil Nadu) and northeast India served as the source of the ancient Mesopotamian mtDNA gene pool, mtDNA of these ancient Mesopotamians probably contributed by Tamil merchants who were involved in the Indo-Roman trade.

  9. Response of a Microbial Iron Cycling Ecosystem From a Glacial Meltwater Stream to Perturbations in Organic Matter Availibility.

    Science.gov (United States)

    Bush, T.; Butler, I. B.; Williamson, H.; Nixon, S. L.; Cousins, C.; Bryce, C. C.; Fox-Powell, M.; Free, A.; Allen, R.

    2014-12-01

    Microbial iron cycling plays an essential role in biogeochemistry, but iron-cycling microbial ecosystems are mainly studied in situ, making it difficult to apply well-controlled perturbations. The iron cycle is strongly coupled to other biogeochemical cycles (particularly the sulfur cycle) and thus its response to perturbations has wide significance. The microbial iron cycle in glacial environments is important as glacial runoff is thought to contribute significant concentrations of free iron to the global iron cycle annually. We have used iron-cycling sediment-water microbial microcosms (Winogradsky columns) as a controlled experimental model in which to study the response to perturbations of iron-cycling microbial ecosystems, using sediment from a high altitude glacial meltwater stream. The microbial iron cycle in glacial environments is important as glacial runoff is thought to contribute significant concentrations of free iron to the global iron cycle annually. We analyse ecosystem state by measuring detailed depth profiles of free iron and oxygen. Upon adding organic matter we observe a sudden transition to a reduced state (dominated by Fe2+) . We hypothesize that this occurs because higher concentrations of organic matter stimulate the microbial reduction of ferrihydrite (the iron source), by providing increased availability of electron donors for the reduction of iron. Using high-throughput sequencing we also analyse how the microbial community changes with the perturbation. As well as providing insight into present-day biogeochemical cycles, our results may also have implications for ancient environments, such as ferruginous Proterozoic oceans.

  10. Forceful DuetA Comparison Between "Sublimity"in Ancient Rome and "Vigor of Style" in Jianan Period%雄浑二重奏——古罗马“崇高”与建安“风骨”的比较

    Institute of Scientific and Technical Information of China (English)

    简梦莹

    2012-01-01

    中国汉末魏.初时期文学所特有的“风骨”风格与古罗马时期所崇尚的“崇高”都体现了中西方人民对雄浑的阳剐之美的崇尚。他们时代接近,风格相仿.可谓是世界文学史上早期的“雄浑”二重奏。但是在追求雄浑的道路上。中国古代文论家远没有古代西方学者们的论述严谨缜密。由于地域、文化、社会背景的不同,他们在描写内容、表现形式上都有差异,但是对文质合一的文学之美的追求却高度一致。我们发现阳刚这种雄浑之美除了是古代先民在生活中所共同向往、追求的可与自然环境相抗衡的力量外,我们还找到了在公元前后通过丝绸之路进行文化交流的实证。这无疑又为我们打开了新的思路,在探索中西文论的比较中加入二者文化互相交融、互相影响的重要因素。%The unique "Vigor of Style" in Chinese literature during the period between the late Eastern Han Dynasty and the early Wei-jin Period and "Sublimity" advocated in ancient Roman period Mike embody both Chinese people and Western people' s advocacy of forceful masculine beauty. They are close in style and age and can be described as the early "forceful" duet in the history of the world literature. But in the pursuit of forcefulness, ancient western scholars expounded their ideas more rigorously and meticulously than the ancientChinese literary critics. Due to different geographical, cultural, and social backgrounds, their descriptions differed in contents and forms, but their pursuit of the unity of literary quality and beauty was highly consistent. We have found that vigorous masculine beauty was the power which all our ancient ancestors yearned for and pursued in their lives and could compete with the natural environment. We have also got the evidence for cultural exchange that was carried out through the Silk Road around the Christian Era. It undoubtedly broadens our

  11. Understanding the glacial methane cycle

    Science.gov (United States)

    Hopcroft, Peter O.; Valdes, Paul J.; O'Connor, Fiona M.; Kaplan, Jed O.; Beerling, David J.

    2017-02-01

    Atmospheric methane (CH4) varied with climate during the Quaternary, rising from a concentration of 375 p.p.b.v. during the last glacial maximum (LGM) 21,000 years ago, to 680 p.p.b.v. at the beginning of the industrial revolution. However, the causes of this increase remain unclear; proposed hypotheses rely on fluctuations in either the magnitude of CH4 sources or CH4 atmospheric lifetime, or both. Here we use an Earth System model to provide a comprehensive assessment of these competing hypotheses, including estimates of uncertainty. We show that in this model, the global LGM CH4 source was reduced by 28-46%, and the lifetime increased by 2-8%, with a best-estimate LGM CH4 concentration of 463-480 p.p.b.v. Simulating the observed LGM concentration requires a 46-49% reduction in sources, indicating that we cannot reconcile the observed amplitude. This highlights the need for better understanding of the effects of low CO2 and cooler climate on wetlands and other natural CH4 sources.

  12. Characterization of Ancient Tripitaka

    Science.gov (United States)

    Gong, Y. X.; Geng, L.; Gong, D. C.

    2015-08-01

    Tripitaka is the world's most comprehensive version of Buddhist sutra. There are limited numbers of Tripitaka currently preserved, most of them present various patterns of degradation. As little is known about the materials and crafts used in Tripitaka, it appeared necessary to identify them, and to further define adapted conservation treatment. In this work, a study concerning the paper source and dyestuff of the Tripitaka from approximate 16th century was carried out using fiber analysis and thin-layer chromatography (TLC). The results proved that the papers were mainly made from hemp or bark of mulberry tree, and indigo was used for colorizing the paper. At the end, we provide with suggestions for protecting and restoring the ancient Tripitaka.

  13. Late Quaternary Glacial Chronology in the Cordillera de Talamanca, Costa Rica, Investigated Using Cosmogenic Cl-36 Surface Exposure Dating

    Science.gov (United States)

    Li, Y.; Potter, R.; Horn, S.; Orvis, K. H.

    2015-12-01

    The role of the tropics in past and future climate change has garnered significant attention in recent decades, but debate still exists over climate linkages between the tropics and the middle and high latitudes. Glaciers in tropical mountains are highly sensitive indicators of climate, and glacial landforms left behind by past glacier fluctuations provide key evidence of paleoclimate trends and their forcing mechanisms. We investigated late Quaternary glacial chronology from two glaciated valleys on the Chirripó massif in the Cordillera de Talamanca, Costa Rica. Previous studies in this highland have constrained the most recent deglaciation to 12.4-9.7 ka cal BP based on radiocarbon dates on basal sediments of glacial lakes within the cirque at the head of the Morrenas Valley. However, no studies have been conducted to constrain the ages of the moraines located down valley. We dated the formation ages of these moraines in the Morrenas and Talari valleys using cosmogenic Cl-36 surface exposure dating. Our results indicate a major glacial event ~21-18 ka, broadly synchronous with the global Last Glacial Maximum (LGM). Glaciers during this period advanced 3.2-3.4 km down valley on both sides of the Chirripó massif. Our ages also suggest periods of glacial retreat or standstills ~18-10 ka before complete deglaciation of this highland ~10 ka. These results provide insight into the timing and extent of glacial events in this tropical highland that is of critical importance for reconstructing regional and global climate patterns.

  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...... to sudden jumps in erosion rate and fjord formation along margins that experienced periodic ice sheet configurations in the Quaternary. Egholm, D. L. et al. Modeling the flow of glaciers in steep terrains: The integrated second-order shallow ice approximation (iSOSIA). Journal of Geophysical Research, 116...

  15. History of glacial terminations from the Tiber River, Rome: Insights into glacial forcing mechanisms

    Science.gov (United States)

    Marra, Fabrizio; Florindo, Fabio; Boschi, Enzo

    2008-06-01

    We document the aggradational history of the Tiber River delta through the last 17,000 years by means of 17 new 14C ages from peat or wood collected from the delta sediment. An abrupt change in sediment clast size, grading from gravel to clay, occurred between 13.63 (±0.20) and 12.80 (±0.15) ka, indicating that it was synchronous with the last glacial termination, with no appreciable phase lag. Knowing this phase relationship enables us to reduce the magnitudes of age uncertainties for aggradational sections corresponding to glacial terminations IX through III, which we had dated previously by 40Ar/39Ar methods. Glacial terminations VIII, VI, and IV precede beyond 95% confidence the ages predicted by Northern Hemisphere summer insolation maxima. Additionally, we find that each of these seven glacial terminations follows particularly mild insolation minima, which we suggest may be regarded as the preconditioning factor to trigger a glacial termination.

  16. Eternal Egypt: Masterworks of Ancient Art from the British Museum. Learning from Exhibitions.

    Science.gov (United States)

    Johnson, Mark M.

    2001-01-01

    Introduces the exhibition "Eternal Egypt: Masterworks of Ancient Art from the British Museum" that explores the four major periods of Egyptian history. Provides background information on ancient Egypt and describes the art that was present in each of the four kingdoms. (CMK)

  17. Extinct 244Pu in Ancient Zircons

    Science.gov (United States)

    Turner, Grenville; Harrison, T. Mark; Holland, Greg; Mojzsis, Stephen J.; Gilmour, Jamie

    2004-10-01

    We have found evidence, in the form of fissiogenic xenon isotopes, for in situ decay of 244Pu in individual 4.1- to 4.2-billion-year-old zircons from the Jack Hills region of Western Australia. Because of its short half-life, 82 million years, 244Pu was extinct within 600 million years of Earth's formation. Detrital zircons are the only known relics to have survived from this period, and a study of their Pu geochemistry will allow us to date ancient metamorphic events and determine the terrestrial Pu/U ratio for comparison with the solar ratio.

  18. Archaeological sites as indicators of ancient shorelines

    Digital Repository Service at National Institute of Oceanography (India)

    Vora, K.H.; Gaur, A.S.; Sundaresh; Tripati, S.

    -Type text/plain; charset=ISO-8859-1 Archaeological Sites as Indicators of Ancient Shorelines K H Vora, A. S. Gnur. Sundaresh and S. Tripati National Institute of Oceanogr-aplzy, Dona Paula, Goa Ernail: vora@nio.org Abstract During the late... Coastal areas of the continents have been the focal points of the emergence of the civilization. For in- stance, the Indian Ocean witnessed the rise of 3 major the Bronze Age Civilizations around it during the mid- Holocene period. Ocean has played...

  19. The Charm of An Ancient Southern City

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    AN artistic narrow bridge winds into a place of pavilions, terraces and open halls, all under the pleasant shade of green trees. This is Mist-Water Pavilion Park in Gantang Lake in the city of Jiujiang, Jiangxi Province. When you stand here in the quiet and elegant historic garden and look out over the water on all four sides, you can’t help but think of the ancient war that took place on this very spot 1,700 years ago. During the Three Kingdoms Period (220-280), this was

  20. Layout of Ancient Maya Cities

    Science.gov (United States)

    Aylesworth, Grant R.

    Although there is little doubt that the ancient Maya of Mesoamerica laid their cities out based, in part, on astronomical considerations, the proliferation of "cosmograms" in contemporary scholarly discourse has complicated matters for the acceptance of rigorous archaeoastronomical research.

  1. Astronomical Significance of Ancient Monuments

    Science.gov (United States)

    Simonia, I.

    2011-06-01

    Astronomical significance of Gokhnari megalithic monument (eastern Georgia) is considered. Possible connection of Amirani ancient legend with Gokhnari monument is discussed. Concepts of starry practicality and solar stations are proposed.

  2. The glacial relief in the Leaota Mountains

    Directory of Open Access Journals (Sweden)

    George MURĂTOREANU

    2008-05-01

    Full Text Available The presence of glacial relief in the Romanian medium height massifs is still controversial. The medium height mountains, such as theLeaota Mountains (in the Bucegi group, with maximum altitudes of almost 2000 m andmedium altitudes of approximately 1250 m, can display traces of glacial relief dating from theUpper Pleistocene. The aim of this article is to provide evidence about the presence of theglacial morphology in the northern part of the Leaota Peak, the main orographic node in themassif with the same name. Thus, on the basis of field observations, of topographical mapanalysis and by using the geographic information systems which made possible a detailedmorphometric analysis, I was able to gather evidence proving the existence of a glacial cirquein the Leaota Mountains. The arguments put forward in this article show that the glacial reliefis represented in the Leaota Mountains through a small-size suspended glacial cirque, whichdisplays all the morphologic elements proving the existence of glaciation in this massif.

  3. Sedimentology and clast fabric of subaerial debris flow facies in a glacially-influenced alluvial fan

    Science.gov (United States)

    Eyles, N.; Kocsis, S.

    1988-09-01

    A large alluvial fan (2 km 2), constructed between 11,000 and 7000 years B.P. at the mouth of Cinquefoil Creek in interior British Columbia, Canada, is identified as "glacially-influenced, debris flow-dominated". The fan was rapidly constructed during and immediately after deglaciation when large volumes of glacial debris were resedimented downslope; fans of this type are widespread in the glaciated portion of the North American Cordillera. Diamict facies, deposited as debris flows, account for 48% of the fan volume, sheetflodd gravels 37%, and other facies 15%. Diamicts show three facies types; crudely-bedded facies containing rafts of soft sediment that are attributed to downslope collapse and mixing of heterogeneous glacial deposits. These occur within the core of the fan. Massive and weakly graded (inverse to normal) diamict facies, derived from the downslope flow of weathered volcanic bedrock, occur within a well-defined bed that can be traced across the entire fan. The occurrence of weakly graded facies as lateral equivalents to massive facies within the same bed, implies the partial development of turbulent, high-velocity "streams" within a viscous debris flow moving over a slope of 6°. Clast fabrics in these facies show weakly-clustered a-axes dipping up and downslope comparable to other debris flows and lahars. The Cinquefoil fan, its internal structure and facies, provides a good "modern" analogue for ancient diamictite sequences deposited in areas of active uplift, rifting and glaciation.

  4. Interhemispheric controls on deep ocean circulation and carbon chemistry during the last two glacial cycles

    Digital Repository Service at National Institute of Oceanography (India)

    Wilson, D.J.; Galy, A; Piotrowski, A; Banakar, V.K.

    circulation changes through glacial cycles. In this study, we use neodymium (Nd) and carbon isotopes from a deep Indian Ocean sediment core to reconstruct water mass mixing and carbon cycling in Circumpolar Deep Water over the past 250 thousand years, a period...

  5. Glacial lakes Buni and Jezerce: Albania

    Directory of Open Access Journals (Sweden)

    Milivojević Milovan

    2005-01-01

    Full Text Available The paper presents glacial lakes and glacial relief forms at the foothill of the peak Maja Jezerce in Mt. Prokletije in Albania, near the border with Montenegro. The group of lakes Buni and Jezerce, which consists of six lakes and which genetically belongs to glacial-erosional lakes, is analyzed. Lakes are situated at the cirque bottom, between the moraines and limestone ridges. Except presented morphometric characteristics of lake basins, data about cirque are given, as well as the reconstruction of the glacier which was formed here. Recent erosion processes are intensive in this area and have considerably changed post-Pleistocene morphology of the lake, as well as the cirque bottom.

  6. 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.

  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. 中亚昭苏黄土剖面粒度记录的末次冰期以来气候变化历史%History of Climate Change Recorded by Grain Size at the Zhaosu Loess Section in the Central Asia since the Last Glacial Period

    Institute of Scientific and Technical Information of China (English)

    李传想; 宋友桂; 千琳勃; 王乐民

    2011-01-01

    in the Ili loess may be mainly derived from the Central Desert region,only very small part of the clay results from the role of weathering and pedogenesis or debris.Therefore,given the regional topography and circulation conditions,the dust sources may be mainly from its western desert region of Central Asia,the annually prevalent westerlies and distal dust may play an important role in the formation of the Ili loess. According to the variations of the content of the loess grain size,the Ili region's climate change can be divided into four stages since the last glaciation:(74 ~ 60.2 ka) cold period,(60.2 ~ 30.4 ka) warm period,(30.4 ~ 11 ka) cold period and 11 ka warm and dry period.The abrupt climate events reflected from changes in atmospheric circulation revealed by loess grain size at the Zhaosu section loess can be well compared with the Heinrich events and the Younger Dryas cold event as well as D-O cycles revealed by the oxygen isotope records from GISP2 since the last glaciation,suggesting that the Ili region dominated westerlies is likely to be a simultaneous change with the high latitude climate of the Northern Hemisphere since the last glacial period.

  9. Dendroclimatic trend and glacial fluctuations in the Central Italian Alps

    Science.gov (United States)

    Pelfini, M.; Santilli, M.; D Agata, C.; Diolaiuti, G.; Smiraglia, C.

    2003-04-01

    In the Alpine environment, one of the main limiting factors for tree growth is the thermal conditions of the vegetative season. The conifers at high altitude, if not subject to others disturbs, such as geomorphological processes or biological interferences, undergo a development, from which the width of annual rings depends. Five chronologies few centuries long, obtained for the species Larix decidua Mill. and Pinus cembra L. from different valleys of the Central Italian Alps (Alpisella, Valfurva, Gavia and Solda) in proximity of timberline (2000-2550 m of altitude), were analysed and their climatic signal gained; this last one was then related to the recent glacial fluctuations. The chronologies are the averages of many dendrochronological indicized curves obtained from dominant trees with regular growth and extended from 13th-17th century up to the present. The time intervals of the chronologies are the following ones: Pinus cembra: 1752-1999 for Valfurva; 1607-1999 for Gavia; 1593-1999 for Val Solda. With regard to Larix decidua: 1252-1998 for Val Solda; 1784-2001 for Alpisella. The good correspondence between the various chronologies allows to consider them representative of the climatic regional signal. In order to evidence climatic evolution, linear trends based on running mean with period of 11 years have been constructed. Those curves have been compared between them and then overlapped and mediated in order to obtain a climatic signal of regional value that excludes eventual local anomalies. Finally, the growth variations in the chronologies have been compared to known alpine climatic variations and glacial fluctuations. In particular time-distance curves (curves of cumulated frontal variations) of some glaciers from the Ortles-Cevedale Group were utilized. The periods of tree rings growth rate reduction appear well correlated to glacial advancing phases of the Little Ice Age and of the following phases. In particular, growth rate reductions are observable

  10. Should precise numerical dating overrule glacial geomorphology?

    Science.gov (United States)

    Winkler, Stefan

    2016-04-01

    Numerical age dating techniques, namely different types of terrestrial cosmogenic nuclide dating (TCND), have achieved an impressive progress in both laboratory precision and regional calibration models during the past few decades. It is now possible to apply precise TCND even to young landforms like Late Holocene moraines, a task seemed hardly achievable just about 15 years ago. An increasing number of studies provide very precise TCND ages for boulders from Late Holocene moraines enabling related reconstruction of glacier chronologies and the interpretation of these glacial landforms in a palaeoclimatological context. These studies may also solve previous controversies about different ages assigned to moraines obtained by different dating techniques, for example relative-age dating techniques or techniques combining relative-age dating with few fixed points derived from numerical age dating. There are a few cases, for example Mueller Glacier and nearby long debris-covered valley glacier in Aoraki/Mt.Cook National Park (Southern Alps, New Zealand), where the apparent "supremacy" of TCND-ages seem to overrule glacial geomorphological principles. Enabled by a comparatively high number of individual boulders precisely dated by TCND, moraine ridges on those glacier forelands have been primarily clustered on basis of these boulder ages rather than on their corresponding morphological position. To the extreme, segments of a particular moraine complex morphologically and sedimentologically proven to be formed during one event have become split and classified as two separate "moraines" on different parts of the glacier foreland. One ledge of another moraine complex contains 2 TCND-sampled boulders apparently representing two separate "moraines"-clusters of an age difference in the order of 1,500 years. Although recently criticism has been raised regarding the non-contested application of the arithmetic mean for calculation of TCND-ages for individual moraines, this

  11. Glacial stages and post-glacial environmental evolution in the Upper Garonne valley, Central Pyrenees.

    Science.gov (United States)

    Fernandes, M; Oliva, M; Palma, P; Ruiz-Fernández, J; Lopes, L

    2017-04-15

    The maximum glacial extent in the Central Pyrenees during the Last Glaciation is known to have occurred before the global Last Glacial Maximum, but the succession of cold events afterwards and their impact on the landscape are still relatively unknown. This study focuses on the environmental evolution in the upper valley of the Garonne River since the Last Glaciation. Geomorphological mapping allows analysis of the spatial distribution of inherited and current processes and landforms in the study area. The distribution of glacial records (moraines, till, erratic boulders, glacial thresholds) suggests the existence of four glacial stages, from the maximum expansion to the end of the glaciation. GIS modeling allows quantification of the Equilibrium Line Altitude, extent, thickness and volume of ice in each glacial stage. During the first stage, the Garonne glacier reached 460m in the Loures-Barousse-Barbazan basin, where it formed a piedmont glacier 88km from the head and extended over 960km(2). At a second stage of glacier stabilization during the deglaciation process, the valley glaciers were 12-23km from the head until elevations of 1000-1850m, covering an area of 157km(2). Glaciers during stage three remained isolated in the upper parts of the valley, at heights of 2050-2200m and 2.6-4.5km from the head, with a glacial surface of 16km(2). In stage four, cirque glaciers were formed between 2260m and 2590m, with a length of 0.4-2km and a glacial area of 5.7km(2). Also, the wide range of periglacial, slope, nival and alluvial landforms existing in the formerly glaciated environments allows reconstruction of the post-glacial environmental dynamics in the upper Garonne basin. Today, the highest lands are organized following three elevation belts: subnival (1500-1900m), nival (1900-2300m) and periglacial/cryonival (2300-2800m).

  12. Global glacial fluctuations in response to climatic change in the past 40 a

    Institute of Scientific and Technical Information of China (English)

    丁永建

    1996-01-01

    Analyses on glacier fluctuations for the past 40 a show that glacial fluctuations were obviously regional over the world. Amplitudes of glacier fluctuations were smaller in northern Europe and high Asia (H Asia) regions than in northern America and the Alps regions. Retreating glaciers were dominant in northern European and high Asia regions, while remarkable glacial advance emerged in different periods in northern America and the Alps regions. Sensitivity of glaciers in the varying scales to climatic change was different. Time lag for reactions to climatic change between larger glaciers (length >5 km) and smaller glaciers (length≤ 5km) has been found. In the globe, glacial fluctuations well correspond to climatic change. Fluctuation lags behind climatic change were about 8 a for larger glaciers and about 2 a for smaller glaciers.

  13. Post-Glacial Development of Western North Atlantic - Labrador Sea Oceanographic Circulation

    DEFF Research Database (Denmark)

    Sheldon, Christina

    2015-01-01

    North Atlantic. A brief stratification event was recorded in Placentia Bay, likely tied to the drainage of glacial Lake Agassiz, after which the Labrador Current strengthened. The Labrador Current remained the major influence around Newfoundland and the western North Atlantic. During the late Holocene...... impact on the Greenland margins after the end of the last glacial period and through the Holocene, are examined based on analyses of sediment cores from the Uummannaq Trough, West Greenland. Marine sediment cores were taken from the Uummannaq Trough on the continental shelf of central West Greenland....... The core sites were chosen in an effort to track the retreat of the edge of the ice sheet after the Last Glacial Maximum. Similar to the other core sites, the cores were analysed using benthic foraminiferal assemblages in addition to bathymetry, quantitative x-ray diffraction analyses, and lithological...

  14. Carbonaceous matter deposition in the high glacial regions of the Tibetan Plateau

    Science.gov (United States)

    Li, Chaoliu; Chen, Pengfei; Kang, Shichang; Yan, Fangping; Li, Xiaofei; Qu, Bin; Sillanpää, Mika

    2016-09-01

    Carbonaceous matter at glacial region plays important role in river ecosystems fed by glacier and albedo reduction of glacier surface. However, currently, limited knowledge are available on the carbonaceous matter within the glacial region of the Tibetan Plateau (TP). In this study, the data from six snowpits in the glacial region across the TP were reported. The results showed that dissolved organic carbon (DOC) concentrations of snowpit samples of the TP were comparable to those of European Alps and the Arctic. The ratio of DOC to carbonaceous matter (40.25 ± 8.98%) was lower than that of Alpine glaciers, thus indicating greater particulate carbon content in the TP glacial region. In addition, the DOC was significantly correlated with insoluble particulate carbon (IPC), indicating that IPC and DOC likely came from the same sources. Spatially, the DOC concentration decreased from the north (0.42 ± 0.29 mg-C L-1) to the south TP (0.15 ± 0.06 mg-C L-1), which was consistent with variations in the distribution of dust storm on the TP. Principal component analysis of major ions and DOC showed that mineral dust contributed the major part of DOC, followed by biogenic sources such as agriculture and livestock. Finally, based on DOC concentrations and precipitation amounts at different periods, the mean annul flux of DOC in the glacial region of the TP was calculated to be 0.11 ± 0.05 g-C m-2 yr-1.

  15. Bifurcations and strange nonchaotic attractors in a phase oscillator model of glacial-interglacial cycles

    CERN Document Server

    Mitsui, Takahito; Aihara, Kazuyuki

    2015-01-01

    Glacial-interglacial cycles are large variations in continental ice mass and greenhouse gases, which have dominated climate variability over the Quaternary. The dominant periodicity of the cycles is $\\sim $40 kyr before the so-called middle Pleistocene transition between $\\sim$1.2 and $\\sim$0.7 Myr ago, and it is $\\sim $100 kyr after the transition. In this paper, the dynamics of glacial-interglacial cycles are investigated using a phase oscillator model forced by the time-varying incoming solar radiation (insolation). We analyze the bifurcations of the system and show that strange nonchaotic attractors appear through nonsmooth saddle-node bifurcations of tori. The bifurcation analysis indicates that mode-locking is likely to occur for the 41 kyr glacial cycles but not likely for the 100 kyr glacial cycles. The sequence of mode-locked 41 kyr cycles is robust to small parameter changes. However, the sequence of 100 kyr glacial cycles can be sensitive to parameter changes when the system has a strange nonchaoti...

  16. Differentiating Hydrothermal, Pedogenic, and Glacial Weathering in a Cold Volcanic Mars-Analog Environment

    Science.gov (United States)

    Scudder, N. A.; Horgan, B.; Havig, J.; Rutledge, A.; Rampe, E. B.; Hamilton, T.

    2016-01-01

    Although the current cold, dry environment of Mars extends back through much of its history, its earliest periods experienced significant water- related surface activity. Both geomorphic features (e.g., paleolakes, deltas, and river valleys) and hydrous mineral detections (e.g., clays and salts) have historically been interpreted to imply a "warm and wet" early Mars climate. More recently, atmospheric modeling studies have struggled to produce early climate conditions with temperatures above 0degC, leading some studies to propose a "cold and icy" early Mars dominated by widespread glaciation with transient melting. However, the alteration mineralogy produced in subglacial environments is not well understood, so the extent to which cold climate glacial weathering can produce the diverse alteration mineralogy observed on Mars is unknown. This summer, we will be conducting a field campaign in a glacial weathering environment in the Cascade Range, OR in order to determine the types of minerals that these environments produce. However, we must first disentangle the effects of glacial weathering from other significant alteration processes. Here we attempt a first understanding of glacial weathering by differentiating rocks and sediments weathered by hydrothermal, pedogenic, and glacial weathering processes in the Cascades volcanic range.

  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. Critical insolation-CO2 relation for diagnosing past and future glacial inception.

    Science.gov (United States)

    Ganopolski, A; Winkelmann, R; Schellnhuber, H J

    2016-01-14

    The past rapid growth of Northern Hemisphere continental ice sheets, which terminated warm and stable climate periods, is generally attributed to reduced summer insolation in boreal latitudes. Yet such summer insolation is near to its minimum at present, and there are no signs of a new ice age. This challenges our understanding of the mechanisms driving glacial cycles and our ability to predict the next glacial inception. Here we propose a critical functional relationship between boreal summer insolation and global carbon dioxide (CO2) concentration, which explains the beginning of the past eight glacial cycles and might anticipate future periods of glacial inception. Using an ensemble of simulations generated by an Earth system model of intermediate complexity constrained by palaeoclimatic data, we suggest that glacial inception was narrowly missed before the beginning of the Industrial Revolution. The missed inception can be accounted for by the combined effect of relatively high late-Holocene CO2 concentrations and the low orbital eccentricity of the Earth. Additionally, our analysis suggests that even in the absence of human perturbations no substantial build-up of ice sheets would occur within the next several thousand years and that the current interglacial would probably last for another 50,000 years. However, moderate anthropogenic cumulative CO2 emissions of 1,000 to 1,500 gigatonnes of carbon will postpone the next glacial inception by at least 100,000 years. Our simulations demonstrate that under natural conditions alone the Earth system would be expected to remain in the present delicately balanced interglacial climate state, steering clear of both large-scale glaciation of the Northern Hemisphere and its complete deglaciation, for an unusually long time.

  19. Critical insolation-CO2 relation for diagnosing past and future glacial inception

    Science.gov (United States)

    Ganopolski, Andrey; Winkelmann, Ricarda; Schellnhuber, Hans Joachim

    2016-04-01

    Past rapid growth of Northern Hemisphere continental ice sheets, which terminated rather stable and warm climate periods, is generally attributed to reduced summer insolation in boreal latitudes (Milanković , 1941; Hays et al., 1976, Paillard, 1998). Yet pertinent summer insolation is near to its minimum at present (Berger and Loutre, 2002), and there are no signs of a new ice age (Kemp et al., 2011). This challenges our scientific understanding of the mechanisms driving glacial cycles and our ability to predict the next glacial inception (Masson-Delmotte et al., 2013). Here we propose a fundamental functional relationship between boreal summer insolation and global CO2 concentration, which explains the beginning of the past eight glacial cycles and can anticipate future periods when glacial inception may occur again. Using a simulations ensemble generated by an Earth system model of intermediate complexity constrained by paleoclimatic data, we show that glacial inception was narrowly missed before the beginning of the Industrial Revolution. This can be explained by the combined effect of relatively high late-Holocene CO2 concentration and low orbital eccentricity of the Earth (Loutre and Berger, 2003). Additionally, our analysis shows that even in the absence of human perturbations no significant buildup of ice sheets would occur within the next several thousand years and that the current interglacial would likely last for another 50,000 years. However, moderate anthropogenic cumulative CO2 emissions of 1000 to 1500 GtC may already postpone the next glacial inception by at least 100,000 years (Archer and Ganopolski, 2005; Paillard, 2006). Our simulations demonstrate that under natural conditions alone the Earth system would be expected to stay in the delicate interglacial climate state, steering clear of both large-scale glaciation of the Northern Hemisphere and its complete deglaciation, for an unusually long time.

  20. [Ancient mental healing and cognitive behavior therapy in comparison].

    Science.gov (United States)

    Hoellen, B; Laux, J

    1988-01-01

    Although cognitive-behavior therapy (CBT) is a relatively new psychotherapeutic approach, the theoretical antecedents actually date back two thousand years, to the period of the hellenistic philosophers. The Stoic Epictetus is often acknowledged as the main philosophical father of CBT and especially of rational-emotive therapy (RET). Beck and Ellis frequently noted that they have drawn upon the writings of the ancient philosophers in developing their psychotherapeutic techniques. This paper reviews some implications of hellenistic philosophy for CBT. We like to show that the teachings of the ancient 'healer of souls' are remarkably consistent with the current theoretical framework and techniques of CBT.

  1. Evidence for Ancient Mesoamerican Earthquakes

    Science.gov (United States)

    Kovach, R. L.; Garcia, B.

    2001-12-01

    Evidence for past earthquake damage at Mesoamerican ruins is often overlooked because of the invasive effects of tropical vegetation and is usually not considered as a casual factor when restoration and reconstruction of many archaeological sites are undertaken. Yet the proximity of many ruins to zones of seismic activity would argue otherwise. Clues as to the types of damage which should be soughtwere offered in September 1999 when the M = 7.5 Oaxaca earthquake struck the ruins of Monte Alban, Mexico, where archaeological renovations were underway. More than 20 structures were damaged, 5 of them seriously. Damage features noted were walls out of plumb, fractures in walls, floors, basal platforms and tableros, toppling of columns, and deformation, settling and tumbling of walls. A Modified Mercalli Intensity of VII (ground accelerations 18-34 %b) occurred at the site. Within the diffuse landward extension of the Caribbean plate boundary zone M = 7+ earthquakes occur with repeat times of hundreds of years arguing that many Maya sites were subjected to earthquakes. Damage to re-erected and reinforced stelae, walls, and buildings were witnessed at Quirigua, Guatemala, during an expedition underway when then 1976 M = 7.5 Guatemala earthquake on the Motagua fault struck. Excavations also revealed evidence (domestic pttery vessels and skeleton of a child crushed under fallen walls) of an ancient earthquake occurring about the teim of the demise and abandonment of Quirigua in the late 9th century. Striking evidence for sudden earthquake building collapse at the end of the Mayan Classic Period ~A.D. 889 was found at Benque Viejo (Xunantunich), Belize, located 210 north of Quirigua. It is argued that a M = 7.5 to 7.9 earthquake at the end of the Maya Classic period centered in the vicinity of the Chixoy-Polochic and Motagua fault zones cound have produced the contemporaneous earthquake damage to the above sites. As a consequences this earthquake may have accelerated the

  2. Head of all years astronomy and calendars at Qumran in their ancient context

    CERN Document Server

    Ben-Dov, Jonathan

    2008-01-01

    Covering a wide array of sources from ancient Mesopotamia to the Dead Sea Scrolls, this volume offers a different perspective on Jewish apocalyptic time-reckoning during the Second Temple period, based on a calendar year of 364 days.

  3. 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

  4. Late glacial aridity in southern Rocky Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Davis, O.K.; Pitblado, B.L. [Univ. of Arizona, Tucson, AZ (United States)

    1995-09-01

    While the slopes of the present-day Colorado Rocky Mountains are characterized by large stands of subalpine and montane conifers, the Rockies of the late glacial looked dramatically different. Specifically, pollen records suggest that during the late glacial, Artemisia and Gramineae predominated throughout the mountains of Colorado. At some point between 11,000 and 10,000 B.P., however, both Artemisia and grasses underwent a dramatic decline, which can be identified in virtually every pollen diagram produced for Colorado mountain sites, including Como Lake (Sangre de Cristo Mountains), Copley Lake and Splains; Gulch (near Crested Butte), Molas Lake (San Juan Mountains), and Redrock Lake (Boulder County). Moreover, the same pattern seems to hold for pollen spectra derived for areas adjacent to Colorado, including at sites in the Chuska Mountains of New Mexico and in eastern Wyoming. The implications of this consistent finding are compelling. The closest modem analogues to the Artemisia- and Gramineae-dominated late-glacial Colorado Rockies are found in the relatively arid northern Great Basin, which suggests that annual precipitation was much lower in the late-glacial southern Rocky Mountains than it was throughout the Holocene.

  5. Ancient Maya astronomical tables from Xultun, Guatemala.

    Science.gov (United States)

    Saturno, William A; Stuart, David; Aveni, Anthony F; Rossi, Franco

    2012-05-11

    Maya astronomical tables are recognized in bark-paper books from the Late Postclassic period (1300 to 1521 C.E.), but Classic period (200 to 900 C.E.) precursors have not been found. In 2011, a small painted room was excavated at the extensive ancient Maya ruins of Xultun, Guatemala, dating to the early 9th century C.E. The walls and ceiling of the room are painted with several human figures. Two walls also display a large number of delicate black, red, and incised hieroglyphs. Many of these hieroglyphs are calendrical in nature and relate astronomical computations, including at least two tables concerning the movement of the Moon, and perhaps Mars and Venus. These apparently represent early astronomical tables and may shed light on the later books.

  6. Neonatal medicine in ancient art.

    Science.gov (United States)

    Yurdakök, Murat

    2010-01-01

    There are a limited number of artistic objects from ancient times with particular importance in neonatal medicine. The best examples are figurines from ancient Egypt of Isis nursing Horus, showing the importance of breastfeeding. The earliest images of the human fetus were made by the Olmecs in Mexico around 1200- 400 BCE. One of the earliest representations of congenital anomalies is a figurine of diencephalic twins thought to be the goddess of Anatolia, dated to around 6500 BCE. In addition to these figurines, three sets of twins in the ancient world have medical importance, and Renaissance artists often used them as a subject for their paintings: "direct suckling animals" (Romulus and Remus), "heteropaternal superfecundation" (mother: Leda, fathers: Zeus, the king of the Olympian gods, and Leda's husband, Tyndareus), and "twin-to-twin transfusion" in monozygotic twins (Jacob and Esau).

  7. Ancient "Observatories" - A Relevant Concept?

    Science.gov (United States)

    Belmonte, Juan Antonio

    It is quite common, when reading popular books on astronomy, to see a place referred to as "the oldest observatory in the world". In addition, numerous books on archaeoastronomy, of various levels of quality, frequently refer to the existence of "prehistoric" or "ancient" observatories when describing or citing monuments that were certainly not built with the primary purpose of observing the skies. Internet sources are also guilty of this practice. In this chapter, the different meanings of the word observatory will be analyzed, looking at how their significances can be easily confused or even interchanged. The proclaimed "ancient observatories" are a typical result of this situation. Finally, the relevance of the concept of the ancient observatory will be evaluated.

  8. Potential flood volume of Himalayan glacial lakes

    Directory of Open Access Journals (Sweden)

    K. Fujita

    2013-07-01

    Full Text Available Glacial lakes are potentially dangerous sources of glacial lake outburst floods (GLOFs, and represent a serious natural hazard in Himalayan countries. Despite the development of various indices aimed at determining the outburst probability, an objective evaluation of the thousands of Himalayan glacial lakes has yet to be completed. In this study we propose a single index, based on the depression angle from the lakeshore, which allows the lakes to be assessed using remotely sensed digital elevation models (DEMs. We test our approach on five lakes in Nepal, Bhutan, and Tibet using images taken by the declassified Hexagon KH-9 satellite before these lakes experienced an outburst flood. All five lakes had a steep lakefront area (SLA, on which a depression angle was steeper than our proposed threshold of 10° before the GLOF event, but the SLA was no longer evident after the events. We further calculated the potential flood volume (PFV; i.e., the maximum volume of floodwater that could be released if the lake surface was lowered sufficiently to eradicate the SLA. This approach guarantees repeatability to assess the possibility of GLOF hazards because it requires no particular expertise to carry out, though the PFV does not quantify the GLOF risk. We calculated PFVs for more than 2000 Himalayan glacial lakes using visible band images and DEMs of ASTER data. The PFV distribution follows a power-law function. We found that 794 lakes did not have an SLA, and consequently had a PFV of zero, while we also identified 49 lakes with PFVs of over 10 million m3, which is a comparable volume to that of recorded major GLOFs. This PFV approach allows us to preliminarily identify and prioritize those Himalayan glacial lakes that require further detailed investigation on GLOF hazards and risk.

  9. Skeletal dysplasia in ancient Egypt.

    Science.gov (United States)

    Kozma, Chahira

    2008-12-01

    The ancient Egyptian civilization lasted for over 3000 years and ended in 30 BCE. Many aspects of ancient Egyptian culture, including the existence of skeletal dysplasias, and in particular achondroplasia, are well known through the monuments and records that survived until modern times. The hot and dry climate in Egypt allowed for the preservation of bodies and skeletal anomalies. The oldest dwarf skeleton, the Badarian skeleton (4500 BCE), possibly represents an epiphyseal disorder. Among the remains of dwarfs with achondroplasia from ancient Egypt (2686-2190 BCE), exists a skeleton of a pregnant female, believed to have died during delivery with a baby's remains in situ. British museums have partial skeletons of dwarfs with achondroplasia, humeri probably affected with mucopolysaccharidoses, and a skeleton of a child with osteogenesis imperfecta. Skeletal dysplasia is also found among royal remains. The mummy of the pharaoh Siptah (1342-1197 BCE) shows a deformity of the left leg and foot. A mummified fetus, believed to be the daughter of king Tutankhamun, has scoliosis, spina bifida, and Sprengel deformity. In 2006 I reviewed the previously existing knowledge of dwarfism in ancient Egypt. The purpose of this second historical review is to add to that knowledge with an expanded contribution. The artistic documentation of people with skeletal dysplasia from ancient Egypt is plentiful including hundreds of amulets, statues, and drawing on tomb and temple walls. Examination of artistic reliefs provides a glance of the role of people with skeletal dysplasia and the societal attitudes toward them. Both artistic evidence and moral teachings in ancient Egypt reveal wide integration of individuals with disabilities into the society.

  10. Night blindness and ancient remedy

    Directory of Open Access Journals (Sweden)

    H.A. Hajar Al Binali

    2014-01-01

    Full Text Available The aim of this article is to briefly review the history of night blindness and its treatment from ancient times until the present. The old Egyptians, the Babylonians, the Greeks and the Arabs used animal liver for treatment and successfully cured the disease. The author had the opportunity to observe the application of the old remedy to a patient. Now we know what the ancients did not know, that night blindness is caused by Vitamin A deficiency and the animal liver is the store house for Vitamin A.

  11. Tuberculosis in ancient times

    Directory of Open Access Journals (Sweden)

    Louise Cilliers

    2008-09-01

    Full Text Available In spite of an array of effective antibiotics, tuberculosis is still very common in developing countries where overcrowding, malnutrition and poor hygienic conditions prevail. Over the past 30 years associated HIV infection has worsened the situation by increasing the infection rate and mortality of tuberculosis. Of those diseases caused by a single organism only HIV causes more deaths internationally than tuberculosis. The tubercle bacillus probably first infected man in Neolithic times, and then via infected cattle, but the causative Mycobacteriacea have been in existence for 300 million years. Droplet infection is the most common way of acquiring tuberculosis, although ingestion (e.g. of infected cows’ milk may occur. Tuberculosis probably originated in Africa. The earliest path gnomonic evidence of human tuberculosis in man was found in osteo-archaeological findings of bone tuberculosis (Pott’s disease of the spine in the skeleton of anEgyptian priest from the 21st Dynasty (approximately 1 000 BC. Suggestive but not conclusiveevidence of tuberculotic lesions had been found in even earlier skeletons from Egypt and Europe. Medical hieroglyphics from ancient Egypt are silent on the disease, which could be tuberculosis,as do early Indian and Chinese writings. The Old Testament refers to the disease schachapeth, translated as phthisis in the Greek Septuagint. Although the Bible is not specific about this condition, tuberculosis is still called schachapeth in modern Hebrew. In pre-Hippocratic Greece Homer did not mention phthisis, a word meaning non-specific wasting of the body. However. Alexander of Tralles (6th century BC seemed to narrow the concept down to a specific disease, and in the Hippocratic Corpus (5th-4th centuries BC phthisis can be recognised as tuberculosis. It was predominantly a respiratory disease commonly seen and considered to be caused by an imbalance of bodily humours. It was commonest in autumn, winter and spring

  12. A conceptual model for glacial cycles and the middle Pleistocene transition

    Science.gov (United States)

    Daruka, István; Ditlevsen, Peter D.

    2016-01-01

    Milankovitch's astronomical theory of glacial cycles, attributing ice age climate oscillations to orbital changes in Northern-Hemisphere insolation, is challenged by the paleoclimatic record. The climatic response to the variations in insolation is far from trivial. In general the glacial cycles are highly asymmetric in time, with slow cooling from the interglacials to the glacials (inceptions) and very rapid warming from the glacials to the interglacials (terminations). We shall refer to this fast-slow dynamics as the "saw-tooth" shape of the paleoclimatic record. This is non-linearly related to the time-symmetric variations in the orbital forcing. However, the most pronounced challenge to the Milankovitch theory is the middle Pleistocene transition (MPT) occurring about one million years ago. During that event, the prevailing 41 kyr glacial cycles, corresponding to the almost harmonic obliquity cycle were replaced by longer saw-tooth shaped cycles with a time-scale around 100 kyr. The MPT must have been driven by internal changes in climate response, since it does not correspond to any apparent changes in the orbital forcing. In order to identify possible mechanisms causing the observed changes in glacial dynamics, it is relevant to study simplified models with the capability of generating temporal behavior similar to the observed records. We present a simple oscillator type model approach, with two variables, a temperature anomaly and a climatic memory term. The generalization of the ice albedo feedback is included in terms of an effective multiplicative coupling between this latter climatic memory term (representing the internal degrees of freedom) and the external drive. The simple model reproduces the temporal asymmetry of the late Pleistocene glacial cycles and suggests that the MPT can be explained as a regime shift, aided by climatic noise, from a period 1 frequency locking to the obliquity cycle to a period 2-3 frequency locking to the same obliquity

  13. 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

  14. Chronology and provenance of last-glacial (Peoria) loess in western Iowa and paleoclimatic implications

    Science.gov (United States)

    Muhs, Daniel R.; Bettis, E. Arthur; Roberts, Helen M.; Harlan, Stephen S.; Paces, James B.; Reynolds, Richard L.

    2013-01-01

    Geologic archives show that the Earth was dustier during the last glacial period. One model suggests that increased gustiness (stronger, more frequent winds) enhanced dustiness. We tested this at Loveland, Iowa, one of the thickest deposits of last-glacial-age (Peoria) loess in the world. Based on K/Rb and Ba/Rb, loess was derived not only from glaciogenic sources of the Missouri River, but also distal loess from non-glacial sources in Nebraska. Optically stimulated luminescence (OSL) ages provide the first detailed chronology of Peoria Loess at Loveland. Deposition began after ~ 27 ka and continued until ~ 17 ka. OSL ages also indicate that mass accumulation rates (MARs) of loess were not constant. MARs were highest and grain size was coarsest during the time of middle Peoria Loess accretion, ~ 23 ka, when ~ 10 m of loess accumulated in no more than ~ 2000 yr and possibly much less. The timing of coarsest grain size and highest MAR, indicating strongest winds, coincides with a summer-insolation minimum at high latitudes in North America and the maximum southward extent of the Laurentide ice sheet. These observations suggest that increased dustiness during the last glacial period was driven largely by enhanced gustiness, forced by a steepened meridional temperature gradient.

  15. Dominant factors controlling glacial and interglacial variations in the treeline elevation in tropical Africa.

    Science.gov (United States)

    Wu, Haibin; Guiot, Joël; Brewer, Simon; Guo, Zhengtang; Peng, Changhui

    2007-06-05

    The knowledge of tropical palaeoclimates is crucial for understanding global climate change, because it is a test bench for general circulation models that are ultimately used to predict future global warming. A longstanding issue concerning the last glacial maximum in the tropics is the discrepancy between the decrease in sea-surface temperatures reconstructed from marine proxies and the high-elevation decrease in land temperatures estimated from indicators of treeline elevation. In this study, an improved inverse vegetation modeling approach is used to quantitatively reconstruct palaeoclimate and to estimate the effects of different factors (temperature, precipitation, and atmospheric CO(2) concentration) on changes in treeline elevation based on a set of pollen data covering an altitudinal range from 100 to 3,140 m above sea level in Africa. We show that lowering of the African treeline during the last glacial maximum was primarily triggered by regional drying, especially at upper elevations, and was amplified by decreases in atmospheric CO(2) concentration and perhaps temperature. This contrasts with scenarios for the Holocene and future climates, in which the increase in treeline elevation will be dominated by temperature. Our results suggest that previous temperature changes inferred from tropical treeline shifts may have been overestimated for low-CO(2) glacial periods, because the limiting factors that control changes in treeline elevation differ between glacial and interglacial periods.

  16. Phylogenetic estimation of timescales using ancient DNA

    DEFF Research Database (Denmark)

    Molak, Martyna; Lorenzen, Eline; Shapiro, Beth;

    2013-01-01

    In recent years, ancient DNA has increasingly been used for estimating molecular timescales, particularly in studies of substitution rates and demographic histories. Molecular clocks can be calibrated using temporal information from ancient DNA sequences. This information comes from the ages...

  17. The Glacial-Interglacial Monsoon Recorded by Speleothems from Sulawesi, Indonesia

    Science.gov (United States)

    Kimbrough, A. K.; Gagan, M. K.; Dunbar, G. B.; Krause, C.; Hantoro, W. S.; Cheng, H.; Edwards, R. L.; Shen, C. C.; Sun, H.; Cai, B.; Hellstrom, J. C.; Rifai, H.

    2015-12-01

    The Indo-Pacific Warm Pool is a primary source of heat and moisture to the global atmosphere and a key player in tropical and global climate variability. There is mounting evidence that atmospheric convection and oceanic processes in the tropics can modulate global climate on orbital and sub-orbital timescales. Glacial-interglacial cycles represent the largest natural climate changes over the last 800 kyr with each cycle terminated by rapid global warming and sea level rise. Our understanding of the role and response of tropical atmospheric convection during these periods of dramatic warming is limited. We present the first speleothem paleomonsoon record for southwest Sulawesi (5ºS, 119ºE), spanning two glacial-interglacial cycles, including glacial termination IV (~340 kyr BP) and both phases of termination III (~248 and ~220 kyr BP). This unique record is constructed from multiple stalagmites from two separate caves and is based on a multi-proxy approach (δ18O, δ13C, Mg/Ca, Sr/Ca) that provides insight into the mechanisms controlling Australian-Indonesian summer monsoon variability. Speleothem δ18O and trace element data indicate a rapid increase in rainfall at glacial terminations and wet interglacials. Terminations IV, III, and I are each characterized by an abrupt 3‰ decrease in δ18O. Variability in δ18O leading-in to glacial terminations is also similar, and corresponds to October insolation. Prior to deglaciation, there is a distinct shift to higher δ18O that is synchronized with weak monsoon intervals in Chinese speleothem records. The remarkably consistent pattern among terminations implies that the response of tropical convection to changing background climates is well regulated. Furthermore, we find that speleothem δ13C leads δ18O by ~5 kyr during glacial terminations. The early decrease in speleothem δ13C may reflect the response of tropical vegetation to rising atmospheric CO2 and temperature, rather than regional changes in rainfall.

  18. Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume.

    Science.gov (United States)

    Abe-Ouchi, Ayako; Saito, Fuyuki; Kawamura, Kenji; Raymo, Maureen E; Okuno, Jun'ichi; Takahashi, Kunio; Blatter, Heinz

    2013-08-08

    The growth and reduction of Northern Hemisphere ice sheets over the past million years is dominated by an approximately 100,000-year periodicity and a sawtooth pattern (gradual growth and fast termination). Milankovitch theory proposes that summer insolation at high northern latitudes drives the glacial cycles, and statistical tests have demonstrated that the glacial cycles are indeed linked to eccentricity, obliquity and precession cycles. Yet insolation alone cannot explain the strong 100,000-year cycle, suggesting that internal climatic feedbacks may also be at work. Earlier conceptual models, for example, showed that glacial terminations are associated with the build-up of Northern Hemisphere 'excess ice', but the physical mechanisms underpinning the 100,000-year cycle remain unclear. Here we show, using comprehensive climate and ice-sheet models, that insolation and internal feedbacks between the climate, the ice sheets and the lithosphere-asthenosphere system explain the 100,000-year periodicity. The responses of equilibrium states of ice sheets to summer insolation show hysteresis, with the shape and position of the hysteresis loop playing a key part in determining the periodicities of glacial cycles. The hysteresis loop of the North American ice sheet is such that after inception of the ice sheet, its mass balance remains mostly positive through several precession cycles, whose amplitudes decrease towards an eccentricity minimum. The larger the ice sheet grows and extends towards lower latitudes, the smaller is the insolation required to make the mass balance negative. Therefore, once a large ice sheet is established, a moderate increase in insolation is sufficient to trigger a negative mass balance, leading to an almost complete retreat of the ice sheet within several thousand years. This fast retreat is governed mainly by rapid ablation due to the lowered surface elevation resulting from delayed isostatic rebound, which is the lithosphere

  19. Antikythera Mechanism and the Ancient World

    Directory of Open Access Journals (Sweden)

    A. N. Safronov

    2016-01-01

    Full Text Available In this historical review, the opinions of Ancient Greece philosophers, astronomers, and poets such as Thales Milesian, Pythagoras, Plato, Eudoxus, Aristotle, Archimedes, Cicero, Diogenes Laertius, Iamblichus, Plutarch, Homer, and Aratus about the planet position calculations and about the possibility of predictions of natural phenomena are analyzed. The planet positions were predicted before Eudoxus (probably before Philolaus by a spindle of Ananke and after Eudoxus by Antikythera mechanism. Following Pythagoras and Plato, it is established that the regular seismoacoustic observations were performed. In the Ancient World in the Mediterranean area, there was an extensive network of acoustic stations (~10 pcs, which were located in close proximity to the geologic faults. Also, it is shown that the ship that was carrying Antikythera mechanism (A-Ship was built in 244 BC in Syracuse with direct participation of Archimedes and Archias from Corinthian. Later, the A-Ship was a part of the Roman Republic safety system. The grain volumes, which were delivered to Rome city by large grain vessels, and the population of Rome city in the period 74–71 BC were estimated. Planetary calculator might be used for the chronology of the historical events as a backward prediction in addition to present Radiocarbon dating and Dendrochronology methods.

  20. The eye and its diseases in Ancient Egypt

    DEFF Research Database (Denmark)

    Andersen, S. Ry

    1997-01-01

    Ophthalmology, History of ophthalmology, eyes in the Ancient Egypt, eye disease in Ancient Egypt, porotic hyperostosis, mummification......Ophthalmology, History of ophthalmology, eyes in the Ancient Egypt, eye disease in Ancient Egypt, porotic hyperostosis, mummification...

  1. The ancient art of memory.

    Science.gov (United States)

    Hobson, Allan

    2013-12-01

    Revision of Freud's theory requires a new way of seeking dream meaning. With the idea of elaborative encoding, Sue Llewellyn has provided a method of dream interpretation that takes into account both modern sleep science and the ancient art of memory. Her synthesis is elegant and compelling. But is her hypothesis testable?

  2. Ancient medicine--a review.

    Science.gov (United States)

    Zuskin, Eugenija; Lipozencić, Jasna; Pucarin-Cvetković, Jasna; Mustajbegović, Jadranka; Schachter, Neil; Mucić-Pucić, Branka; Neralić-Meniga, Inja

    2008-01-01

    Different aspects of medicine and/or healing in several societies are presented. In the ancient times as well as today medicine has been closely related to magic, science and religion. Various ancient societies and cultures had developed different views of medicine. It was believed that a human being has two bodies: a visible body that belongs to the earth and an invisible body of heaven. In the earliest prehistoric days, a different kind of medicine was practiced in countries such as Egypt, Greece, Rome, Mesopotamia, India, Tibet, China, and others. In those countries, "medicine people" practiced medicine from the magic to modern physical practices. Medicine was magical and mythological, and diseases were attributed mostly to the supernatural forces. The foundation of modern medicine can be traced back to ancient Greeks. Tibetan culture, for instance, even today, combines spiritual and practical medicine. Chinese medicine developed as a concept of yin and yang, acupuncture and acupressure, and it has even been used in the modern medicine. During medieval Europe, major universities and medical schools were established. In the ancient time, before hospitals had developed, patients were treated mostly in temples.

  3. Ancient and modern environmental DNA

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Winther; Overballe-Petersen, Søren; Ermini, Luca

    2015-01-01

    DNA obtained from environmental samples such as sediments, ice or water (environmental DNA, eDNA), represents an important source of information on past and present biodiversity. It has revealed an ancient forest in Greenland, extended by several thousand years the survival dates for mainland woo...

  4. A Huge Ancient Schwannoma of the Epiglottis.

    Science.gov (United States)

    Lee, Dong Hoon; Kim, Jo Heon; Yoon, Tae Mi; Lee, Joon Kyoo; Lim, Sang Chul

    2016-03-01

    Ancient schwannoma of the epiglottis is extremely rare. The authors report the first case of a patient with a huge ancient schwannoma of the epiglottis. Clinicians should consider the possibility that ancient schwannoma may originate in the epiglottis mimicking the other more frequently observed lesions.

  5. Fingerprinting of glacial silt in lake sediments yields continuous records of alpine glaciation (35–15 ka), western USA

    Science.gov (United States)

    Rosenbaum, Joseph G.; Reynolds, Richard L.; Colman, Steven M.

    2012-01-01

    Fingerprinting glacial silt in last glacial-age sediments from Upper Klamath Lake (UKL) and Bear Lake (BL) provides continuous radiocarbon-dated records of glaciation for the southeastern Cascade Range and northwestern Uinta Mountains, respectively. Comparing of these records to cosmogenic exposure ages from moraines suggests that variations in glacial flour largely reflect glacial extent. The two areas are at similar latitudes and yield similar records of glacial growth and recession, even though UKL lies less than 200 km from the ocean and BL is in the continental interior. As sea level began to fall prior to the global Last Glacial Maximum (LGM), existing glaciers in the UKL area expanded. Near the beginning of the global LGM (26.5 ka), the BL record indicates onset of glaciation and UKL-area glaciers underwent further expansion. Both records indicate that local glaciers reached their maximum extents near the end of the global LGM, remained near their maxima for ~1000 yr, and underwent two stages of retreat separated by a short period of expansion.

  6. A new approach to evaluating landslide hazard in the mountain glacial environment - mass and hypsometry

    Science.gov (United States)

    Reid, Madison L.; Evans, Stephen G.

    2016-04-01

    The magnitude and frequency of glacial hazards is central to the discussion of the effect of climate change in the mountain glacial environment and has persisted as a research question since the 1990s. We propose a new approach to evaluating mass flow (including landslides) hazard in the glacier environment conditioned by temporal and elevation changes in glacier-ice loss. Using digital topographic data sets and InSAR techniques we investigate the hypsometry of ice loss in a well-defined glacial environment in the southwest Coast Mountains of SW British Columbia (the Mount Meager Volcanic Complex - MMVC). The volume and elevation of major mass movements that have taken place in the MMVC since the 1930s is established and compared to the volume and hypsometry of glacial ice loss in the same time period. In the analysis, the volumes of ice loss and landslides are converted to units of mass. The elevation of a sequence of large-scale mass movements do not suggest a close correlation with the elevation or temporal sequence of greatest ice loss. Instead, the temporal relationship between the mass of ice loss and mass lost from slopes in landslides (including ice, rock, and debris) is suggestive of a steady state. The same approach is then applied to the Cordillera Blanca (Peruvian Andes) where we show that the greatest mass moved from the glacier system by glacier-related mass flows since the 1930s, corresponded generally to the period of greatest ice loss suggesting a decay-based response to recent glacier ice loss. As in the MMVC, the elevation of mass flow events is not correlated with the estimated hypsometry of glacial ice loss; in both regions the largest landslide in the period investigated occurred from a high mountain peak defining a topographic divide and where ice loss was minimal. It thus appears that mountain glacial environments exhibit different landslide responses to glacier ice loss that may be conditioned by the rate of ice loss and strongly influenced

  7. Expanding Greenland’s Glacial Record

    DEFF Research Database (Denmark)

    Bjørk, Anders Anker

    Mass loss from the Greenland Ice Sheet and adjecent glaciers and ice caps has accelerated within the last decades, and these changes are accurately observed using a variety of different data products. However, the observational era is relatively short offering little insight into past dynamics. O...... the entire 20th century show rapid and widespread responses to climate change. On a longer time-scale is the Holocene history of Helheim Glacier reconstructed using evidence of glacial presence accumulated in lake sediments....... 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...

  8. The Post-Glacial Species Velocity of Picea glauca following the Last Glacial Maximum in Alaska.

    Science.gov (United States)

    Morrison, B. D.; Napier, J.; Kelly, R.; Li, B.; Heath, K.; Hug, B.; Hu, F.; Greenberg, J. A.

    2015-12-01

    Anthropogenic climate change is leading to dramatic fluctuations to Earth's biodiversity that has not been observed since past interglacial periods. There is rising concern that Earth's warming climate will have significant impacts to current species ranges and the ability of a species to persist in a rapidly changing environment. The paleorecord provides information on past species distributions in relation to climate change, which can illuminate the patterns of potential future distributions of species. Particularly in areas where there are multiple potential limiting factors on a species' range, e.g. temperature, radiation, and evaporative demand, the spatial patterns of species migrations may be particularly complex. In this study, we assessed the change in the distributions of white spruce (Picea glauca) from the Last Glacial Maxima (LGM) to present-day for the entire state of Alaska. To accomplish this, we created species distribution models (SDMs) calibrated from modern vegetation data and high-resolution, downscaled climate surfaces at 60m. These SDMs were applied to downscaled modern and paleoclimate surfaces to produce estimated ranges of white spruce during the LGM and today. From this, we assessed the "species velocity", the rate at which white spruce would need to migrate to keep pace with climate change, with the goal of determining whether the expansion from the LGM to today originated from microclimate refugia. Higher species velocities indicate locations where climate changed drastically and white spruce would have needed to migrate rapidly to persist and avoid local extinction. Conversely, lower species velocities indicated locations where the local climate was changing less rapidly or was within the center of the range of white spruce, and indicated locations where white spruce distributions were unlikely to have changed significantly. Our results indicate the importance of topographic complexity in buffering the effects of climate change

  9. Glacial cycles drive variations in the production of oceanic crust

    CERN Document Server

    Crowley, John W; Huybers, Peter; Langmuir, Charles H; Park, Sung-Hyun

    2014-01-01

    Glacial cycles redistribute water between the oceans and continents causing pressure changes in the upper mantle, with potential consequences for melting of Earth's interior. A numerical model of mid-ocean ridge dynamics that explicitly includes melt transport is used to calculate the melting effects that would be caused by Plio-Pleistocene sea-level variations. Model results interpreted in the context of an analytical approximation predict sea-level induced variations in crustal thickness on the order of hundreds of meters. The specifics of the response depend on rates of sea-level change, mid-ocean ridge spreading rates, and mantle permeability. Spectral analysis of the bathymetry of the Australian-Antarctic ridge shows significant spectral energy near 23, 41, and 100 ky periods, consistent with model results and with the spectral content of Pleistocene sea-level variability. These results support the hypothesis that sea-floor topography records the magmatic response to changes in sea level, reinforcing the...

  10. 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

  11. Impact of brine-induced stratification on the glacial carbon cycle

    Directory of Open Access Journals (Sweden)

    N. Bouttes

    2010-09-01

    Full Text Available During the cold period of the Last Glacial Maximum (LGM, about 21 000 years ago atmospheric CO2 was around 190 ppm, much lower than the pre-industrial concentration of 280 ppm. The causes of this substantial drop remain partially unresolved, despite intense research. Understanding the origin of reduced atmospheric CO2 during glacial times is crucial to comprehend the evolution of the different carbon reservoirs within the Earth system (atmosphere, terrestrial biosphere and ocean. In this context, the ocean is believed to play a major role as it can store large amounts of carbon, especially in the abyss, which is a carbon reservoir that is thought to have expanded during glacial times. To create this larger reservoir, one possible mechanism is to produce very dense glacial waters, thereby stratifying the deep ocean and reducing the carbon exchange between the deep and upper ocean. The existence of such very dense waters has been inferred in the LGM deep Atlantic from sediment pore water salinity and δ18O inferred temperature. Based on these observations, we study the impact of a brine mechanism on the glacial carbon cycle. This mechanism relies on the formation and rapid sinking of brines, very salty water released during sea ice formation, which brings salty dense water down to the bottom of the ocean. It provides two major features: a direct link from the surface to the deep ocean along with an efficient way of setting a strong stratification. We show with the CLIMBER-2 carbon-climate model that such a brine mechanism can account for a significant decrease in atmospheric CO2 and contribute to the glacial-interglacial change. This mechanism can be amplified by low vertical diffusion resulting from the brine-induced stratification. The modeled glacial distribution of oceanic δ13C as well as the deep ocean salinity are substantially improved and better agree with reconstructions from

  12. Impact of brine-induced stratification on the glacial carbon cycle

    Directory of Open Access Journals (Sweden)

    N. Bouttes

    2010-04-01

    Full Text Available During the cold period of the Last Glacial Maximum (LGM, about 21 000 years ago atmospheric CO2 was around 190 ppm (Monnin et al., 2001, much lower than the pre-industrial concentration of 280 ppm. The causes of this substantial drop remain partially unresolved, despite intense research. Understanding the origin of reduced atmospheric CO2 during glacial times is crucial to comprehend the evolution of the different carbon reservoirs within the Earth system (atmosphere, terrestrial biosphere and ocean. In this context, the ocean is believed to play a major role as it can store large amounts of carbon (Sigman and Boyle, 2000, especially in the abyss, which is a carbon reservoir that is thought to have expanded during glacial times. To create this larger reservoir, one possible mechanism is to produce very dense glacial waters, thereby stratifying the deep ocean and reducing the carbon exchange between the deep and surface ocean (Paillard and Parrenin, 2004. The existence of such very dense waters has been inferred in the LGM deep Atlantic from sediment pore water salinity (Adkins et al., 2002. Based on these observations, we study the impact of a brine mechanism on the glacial carbon cycle. This mechanism relies on the formation and rapid sinking of brines, very salty water released during sea ice formation, which brings salty dense water down to the bottom of the ocean. It provides two major features: a direct link from the surface to the deep ocean along with an efficient way of setting a strong stratification. We show with the CLIMBER-2 coupled carbon-climate model (Petoukhov et al., 2000 that such a brine mechanism can account for a significant decrease in atmospheric CO2 and contribute to the glacial-interglacial change. This mechanism can be amplified by low vertical diffusion resulting from the brine-induced stratification. The results obtained substantially improve the modeled glacial distribution of oceanic

  13. Towards an improved inventory of Glacial Lake Outburst Floods in the Himalayas

    Science.gov (United States)

    Veh, Georg; Walz, Ariane; Korup, Oliver; Roessner, Sigrid

    2016-04-01

    The retreat of glaciers in the Himalayas and the associated release of meltwater have prompted the formation and growth of thousands of glacial lakes in the last decades. More than 2,200 of these lakes have developed in unconsolidated moraine material. These lakes can drain in a single event, producing potentially destructive glacial lake outburst floods (GLOFs). Only 44 GLOFs in the Himalayas have been documented in more detail since the 1930s, and evidence for a change, let alone an increase, in the frequency of these flood events remains elusive. The rare occurrence of GLOFs is counterintuitive to our hypothesis that an increasing amount of glacial lakes has to be consistent with a rising amount of outburst floods. Censoring bias affects the GLOF record, such that mostly larger floods with commensurate impact have been registered. Existing glacial lake inventories are also of limited help for the identification of GLOFs, as they were created in irregular time steps using different methodological approach and covering different regional extents. We discuss the key requirements for generating a more continuous, close to yearly time series of glacial lake evolution for the Himalayan mountain range using remote sensing data. To this end, we use sudden changes in glacial lake areas as the key diagnostic of dam breaks and outburst floods, employing the full archive of cloud-free Landsat data (L5, L7 and L8) from 1988 to 2015. SRTM and ALOS World 3D topographic data further improve the automatic detection of glacial lakes in an alpine landscape that is often difficult to access otherwise. Our workflow comprises expert-based classification of water bodies using thresholds and masks from different spectral indices and band ratios. A first evaluation of our mapping approach suggests that GLOFs reported during the study period could be tracked independently by a significant reduction of lake size between two subsequent Landsat scenes. This finding supports the feasibility

  14. Hedera helix L. and damages in Tlos Ancient City

    Directory of Open Access Journals (Sweden)

    Elinç, Z.K.

    2013-03-01

    Full Text Available There are various plant types in Tlos Ancient City of Fethiye district in the Province of Mugla, a city where different residential ruins of Lycia Civilization starting from Classical Age until Byzantine Period. Tlos is an important city in West-Lycia and is situated right on the control point of Lycia Way. Hedera helix L. is one of the plants living in this area, which attracts the attention as it mostly harms the ancient ruins. One of the most important reasons why Hedera helix L. is growing commonly in this region is the perfect ecological circumstances for the growth of this plant of the location where this ancient city is situated in. Additionally the fact that the ruins of the city are left on their fate, is another perfect circumstance for the Hedera helix L. to grow. Climbing or creeping stems of Hedera helix L. stick easily to the objects it touches and encircle them. Due to this characteristic, the walls of the ancient city are covered by this plant. Nevertheless, Hedera helix L. does not only harm the ancient constructions and natural rocks but also woody plants. The harm caused by dried out or cut Hedera helix L. are more than the harm caused by them when they were untouched. The subject of this study is to prove the shape and level of the harm caused by Hedera helix L. on ancient ruins of Tlos. At the same time, this study will underline the fighting methods against Hedera helix L. by comparing similar studies in other countries. Knowledge collected after this study will offer an insight into the excavation and restoration studies undertaken in all Mediterranean countries.

  15. The ancient tropical rainforest tree Symphonia globulifera L. f. (Clusiaceae) was not restricted to postulated Pleistocene refugia in Atlantic Equatorial Africa.

    Science.gov (United States)

    Budde, K B; González-Martínez, S C; Hardy, O J; Heuertz, M

    2013-07-01

    Understanding the history of forests and their species' demographic responses to past disturbances is important for predicting impacts of future environmental changes. Tropical rainforests of the Guineo-Congolian region in Central Africa are believed to have survived the Pleistocene glacial periods in a few major refugia, essentially centred on mountainous regions close to the Atlantic Ocean. We tested this hypothesis by investigating the phylogeographic structure of a widespread, ancient rainforest tree species, Symphonia globulifera L. f. (Clusiaceae), using plastid DNA sequences (chloroplast DNA [cpDNA], psbA-trnH intergenic spacer) and nuclear microsatellites (simple sequence repeats, SSRs). SSRs identified four gene pools located in Benin, West Cameroon, South Cameroon and Gabon, and São Tomé. This structure was also apparent at cpDNA. Approximate Bayesian Computation detected recent bottlenecks approximately dated to the last glacial maximum in Benin, West Cameroon and São Tomé, and an older bottleneck in South Cameroon and Gabon, suggesting a genetic effect of Pleistocene cycles of forest contraction. CpDNA haplotype distribution indicated wide-ranging long-term persistence of S. globulifera both inside and outside of postulated forest refugia. Pollen flow was four times greater than that of seed in South Cameroon and Gabon, which probably enabled rapid population recovery after bottlenecks. Furthermore, our study suggested ecotypic differentiation-coastal or swamp vs terra firme-in S. globulifera. Comparison with other tree phylogeographic studies in Central Africa highlighted the relevance of species-specific responses to environmental change in forest trees.

  16. Ancient engineers' inventions precursors of the present

    CERN Document Server

    Rossi, Cesare

    2017-01-01

    This book describes the inventions and designs of ancient engineers who are the precursors of the present. The period ranges mainly from 300 B.C. to 1600 A.D. with several exceptions. Many of the oldest inventions are documented by archaeological finds, often very little known, mainly from Pompeii, Herculaneum and Stabiae and reveal a surprising modernity in their conception. Most of the inventions presented in the first four parts of the book were conceived up to the late Roman Empire and may be considered as milestones, each in their respective field. The fifth part concentrates on more recent centuries. The sixth part deals with some building construction techniques. Generally, for each of the presented inventions, three elements of research and reference are provided: written documents (the classics), iconic references (coins, bas-reliefs, etc.) and archaeological findings. The authors did not write this book for engineers only; hence they describe all the devices without assuming wide technical knowledge...

  17. Damage and repair of ancient DNA

    DEFF Research Database (Denmark)

    Mitchell, David; Willerslev, Eske; Hansen, Anders

    2005-01-01

    , and extensive degradation. In the course of this review, we will discuss the current aDNA literature describing the importance of aDNA studies as they relate to important biological questions and the difficulties associated with extracting useful information from highly degraded and damaged substrates derived......Under certain conditions small amounts of DNA can survive for long periods of time and can be used as polymerase chain reaction (PCR) substrates for the study of phylogenetic relationships and population genetics of extinct plants and animals, including hominids. Because of extensive DNA...... degradation, these studies are limited to species that lived within the past 10(4)-10(5) years (Late Pleistocene), although DNA sequences from 10(6) years have been reported. Ancient DNA (aDNA) has been used to study phylogenetic relationships of protists, fungi, algae, plants, and higher eukaryotes...

  18. Ancient Humans Influenced the Current Spatial Genetic Structure of Common Walnut Populations in Asia.

    Directory of Open Access Journals (Sweden)

    Paola Pollegioni

    Full Text Available Common walnut (Juglans regia L is an economically important species cultivated worldwide for its wood and nuts. It is generally accepted that J. regia survived and grew spontaneously in almost completely isolated stands in its Asian native range after the Last Glacial Maximum. Despite its natural geographic isolation, J. regia evolved over many centuries under the influence of human management and exploitation. We evaluated the hypothesis that the current distribution of natural genetic resources of common walnut in Asia is, at least in part, the product of ancient anthropogenic dispersal, human cultural interactions, and afforestation. Genetic analysis combined with ethno-linguistic and historical data indicated that ancient trade routes such as the Persian Royal Road and Silk Road enabled long-distance dispersal of J. regia from Iran and Trans-Caucasus to Central Asia, and from Western to Eastern China. Ancient commerce also disrupted the local spatial genetic structure of autochthonous walnut populations between Tashkent and Samarkand (Central-Eastern Uzbekistan, where the northern and central routes of the Northern Silk Road converged. A significant association between ancient language phyla and the genetic structure of walnut populations is reported even after adjustment for geographic distances that could have affected both walnut gene flow and human commerce over the centuries. Beyond the economic importance of common walnut, our study delineates an alternative approach for understanding how the genetic resources of long-lived perennial tree species may be affected by the interaction of geography and human history.

  19. Water quality of two glacial alpine Italian lakes.

    Science.gov (United States)

    Zelano, Vincenzo; Zambrotta, Maria; Defilippi, Albino; Torazzo, Annamaria

    2005-01-01

    The purpose of this study was to characterize, in a period of one year, two glacial lakes, Alice and Meugliano, located in an alpine reservoir on the basis of physical and chemical features. The two lakes show two periods of mixing: one in the spring and one in the autumn, so can be classified as dimictic lakes. They are characterized by pH, alkalinity, low conductivity and and quite dilute ionic concentrations. With regard to nutrients, most nitrogen occurred in the nitric form in the superficial layers. During the period of thermal stratification, in the anoxic layer NO3- decreases and NH4+ increases, confirming the activity of the anaerobic denitrificant bacteria. Total and soluble phosphorus levels show homogeneity during the cold period at different depths, while with stratification concentrations increase in the hypolimnium and metalimnium. In both lakes there is an inverse correlation between transparency and chlorophyll a. To evaluate the trophic state the conventional criteria of Nurnberg 2 and four lake trophic indices (TSIs) are used. Both evaluations suggest that the two lakes are eutrophic, with worse conditions in Alice. Deviations of the trophic states, based on the relation between TSIs, indicate that factors other than phosphorous limit the algal biomass, and that non-algal particles influence light attenuation

  20. Evidence for the assimilation of ancient glacier organic carbon in a proglacial stream food web

    Science.gov (United States)

    Fellman, Jason; Hood, Eran; Raymond, Peter A.; Hudson, J.H.; Bozeman, Maura; Arimitsu, Mayumi L.

    2015-01-01

    We used natural abundance δ13C, δ15N, and Δ14C to compare trophic linkages between potential carbon sources (leaf litter, epilithic biofilm, and particulate organic matter) and consumers (aquatic macroinvertebrates and fish) in a nonglacial stream and two reaches of the heavily glaciated Herbert River. We tested the hypothesis that proglacial stream food webs are sustained by organic carbon released from glacial ecosystems. Carbon sources and consumers in the nonglacial stream had carbon isotope values that ranged from -30‰ to -25‰ for δ13C and from -14‰ to 53‰ for Δ14C reflecting a food web sustained mainly on contemporary primary production. In contrast, biofilm in the two glacial stream sites was highly Δ14C-depleted (-215‰ to 175‰) relative to the nonglacial stream consistent with the assimilation of ancient glacier organic carbon. IsoSource modeling showed that in upper Herbert River, macroinvertebrates (Δ14C = -171‰ to 22‰) and juvenile salmonids (Δ14C = −102‰ to 17‰) reflected a feeding history of both biofilm (~ 56%) and leaf litter (~ 40%). We estimate that in upper Herbert River on average 36% of the carbon incorporated into consumer biomass is derived from the glacier ecosystem. Thus, 14C-depleted glacial organic carbon was likely transferred to higher trophic levels through a feeding history of bacterial uptake of dissolved organic carbon and subsequent consumption of 14C-depleted biofilm by invertebrates and ultimately fish. Our findings show that the metazoan food web is sustained in part by glacial organic carbon such that future changes in glacial runoff could influence the stability and trophic structure of proglacial aquatic ecosystems.

  1. [Changes of marriage age in ancient China].

    Science.gov (United States)

    Zhang, D

    1991-04-01

    The changes in age of marriage in ancient China can be classified into 3 periods. Around 680 B.C., the government set the age of marriage at 20 for men and at 15 for women. Even though it was written in the works of the Confucian school that men should marry at 30 and women at 20, it was never really followed. The Wei and Jin dynasties provided the longest periods of war and social instability. Large numbers of population died because of war or famine. Because heavy taxes were collected on each member of family, many families did not report marriage or childbirth. In order to encourage childbirth, the government reduced the age of marriage to 15 for men and 13 for women. Administrative and legislative regulation were introduced to force people to marry early, especially women. Incentives were given to families with more women. These policies was enforced due to the imbalance of the sex ratio and reduction of population size. As female infanticides were prevalent because of differential values placed on male and female children, it was difficult for men to find partners to marry. Shortage of women was also the result of the polygamy of the rich and the aristocracy. The imbalance of the sex ratio forced women to marry early. Nevertheless, women getting married too early were not fertile. Infant or child mortality was high among children of young mothers. From the Song to the Ching dynasties, the age of marriage was set at 16 for men and 14 for women. In the ancient times, the population of China was around 60-70 million before the Ching dynasty. Generally speaking, the population size was small. Early marriage was necessary and feasible. Even though fertility in ancient times was high, mortality has high also. Life expectancy ranged form 22 to 35. People needed to marry early and have children early to replace themselves. On the other hand, large land areas and inefficient production tools required a larger labor force. Large population size also represented

  2. Glacial Retreat and Associated Glacial Lake Hazards in the High Tien Shan

    Science.gov (United States)

    Smith, T. T.

    2013-12-01

    A number of studies have identified glacial retreat throughout the greater Himalayan region over the past few decades, but the Karakorum region remains an anomaly with large stagnating or advancing glaciers. The glacial behavior in the Tien Shan is still unclear, as few studies have investigated mass balances in the region. This study focuses on the highest peaks of the Tien Shan mountain range, in the region of Jengish Chokusu along the Kyrgyzstan-China-Kazakhstan border. In a first step, a 30-year time series of Landsat imagery (n=27) and ASTER imagery (n=10) was developed to track glacial growth and retreat in the region. Using a combination of spectral and topographic information, glacial outlines are automatically delineated. As several important glaciers in the study region contain medium to high levels of debris cover, our algorithm also improves upon current methods of detecting debris-covered glaciers by using topography, distance weighting methods, river networks, and additional spectral data. Linked to glacial retreat are glacial lake outburst floods (GLOFs) that have become increasingly common in High Mountain Asia over the last few decades. As glaciers retreat, their melt water is often trapped by weakly bonded moraines. These moraines have been known to fail due to overtopping caused by surge waves created by avalanches, rockslides, or glacial calving. A suite of studies throughout High Mountain Asia have used remotely-sensed data to monitor the formation and growth of glacial lakes. In a second step of the work, lake-area changes over the past 15 years were tracked monthly and seasonally using dense Landsat/ASTER coverage (n=30) with an automatic procedure based on spectral and topographic information. Previous work has identified GLOFs as a significant process for infrastructural damage in the southern Tien Shan/northern Pamir, as well as in the better studied Himalaya region. Lake identification and quantification of lake-growth rates is a valuable

  3. On the glacial and inter-glacial thermohaline circulation and the associated transports of heat and freshwater

    Directory of Open Access Journals (Sweden)

    M. Ballarotta

    2014-03-01

    Full Text Available The change of the thermohaline circulation (THC between the Last Glacial Maximum (LGM, ≈ 21 kyr ago and the present day climate are explored using an Ocean General Circulation Model and stream functions projected in various coordinates. Compared to the present day period, the LGM circulation is reorganised in the Atlantic Ocean, in the Southern Ocean and particularly in the abyssal ocean, mainly due to the different haline stratification. Due to stronger wind stress, the LGM tropical circulation is more vigorous than under modern conditions. Consequently, the maximum tropical transport of heat is slightly larger during the LGM. In the North Atlantic basin, the large sea-ice extent during the LGM constrains the Gulf Stream to propagate in a more zonal direction, reducing the transport of heat towards high latitudes and reorganising the freshwater transport. The LGM circulation is represented as a large intrusion of saline Antarctic Bottom Water into the Northern Hemisphere basins. As a result, the North Atlantic Deep Water is shallower in the LGM simulation. The stream functions in latitude-salinity coordinates and thermohaline coordinates point out the different haline regimes between the glacial and interglacial period, as well as a LGM Conveyor Belt circulation largely driven by enhanced salinity contrast between the Atlantic and the Pacific basin. The thermohaline structure in the LGM simulation is the result of an abyssal circulation that lifts and deviates the Conveyor Belt cell from the area of maximum volumetric distribution, resulting in a ventilated upper layer above a deep stagnant layer, and an Atlantic circulation more isolated from the Pacific. An estimation of the turnover times reveal a deep circulation almost sluggish during the LGM, and a Conveyor Belt cell more vigorous due to the combination of stronger wind stress and shortened circulation route.

  4. Glacial refugia, recolonization patterns and diversification forces in Alpine-endemic Megabunus harvestmen.

    Science.gov (United States)

    Wachter, Gregor A; Papadopoulou, Anna; Muster, Christoph; Arthofer, Wolfgang; Knowles, L Lacey; Steiner, Florian M; Schlick-Steiner, Birgit C

    2016-06-01

    The Pleistocene climatic fluctuations had a huge impact on all life forms, and various hypotheses regarding the survival of organisms during glacial periods have been postulated. In the European Alps, evidence has been found in support of refugia outside the ice shield (massifs de refuge) acting as sources for postglacial recolonization of inner-Alpine areas. In contrast, evidence for survival on nunataks, ice-free areas above the glacier, remains scarce. Here, we combine multivariate genetic analyses with ecological niche models (ENMs) through multiple timescales to elucidate the history of Alpine Megabunus harvestmen throughout the ice ages, a genus that comprises eight high-altitude endemics. ENMs suggest two types of refugia throughout the last glacial maximum, inner-Alpine survival on nunataks for four species and peripheral refugia for further four species. In some geographic regions, the patterns of genetic variation are consistent with long-distance dispersal out of massifs de refuge, repeatedly coupled with geographic parthenogenesis. In other regions, long-term persistence in nunataks may dominate the patterns of genetic divergence. Overall, our results suggest that glacial cycles contributed to allopatric diversification in Alpine Megabunus, both within and at the margins of the ice shield. These findings exemplify the power of ENM projections coupled with genetic analyses to identify hypotheses about the position and the number of glacial refugia and thus to evaluate the role of Pleistocene glaciations in driving species-specific responses of recolonization or persistence that may have contributed to observed patterns of biodiversity.

  5. Glacial legacies on interglacial vegetation at the Pliocene-Pleistocene transition in NE Asia

    Science.gov (United States)

    Herzschuh, Ulrike; Birks, H. John B.; Laepple, Thomas; Andreev, Andrei; Melles, Martin; Brigham-Grette, Julie

    2016-06-01

    Broad-scale climate control of vegetation is widely assumed. Vegetation-climate lags are generally thought to have lasted no more than a few centuries. Here our palaeoecological study challenges this concept over glacial-interglacial timescales. Through multivariate analyses of pollen assemblages from Lake El'gygytgyn, Russian Far East and other data we show that interglacial vegetation during the Plio-Pleistocene transition mainly reflects conditions of the preceding glacial instead of contemporary interglacial climate. Vegetation-climate disequilibrium may persist for several millennia, related to the combined effects of permafrost persistence, distant glacial refugia and fire. In contrast, no effects from the preceding interglacial on glacial vegetation are detected. We propose that disequilibrium was stronger during the Plio-Pleistocene transition than during the Mid-Pliocene Warm Period when, in addition to climate, herbivory was important. By analogy to the past, we suggest today's widespread larch ecosystem on permafrost is not in climate equilibrium. Vegetation-based reconstructions of interglacial climates used to assess atmospheric CO2-temperature relationships may thus yield misleading simulations of past global climate sensitivity.

  6. Genetic Drift. The ancient Egyptian dwarfs of the Walters Art Museum.

    Science.gov (United States)

    Kozma, Chahira

    2010-10-01

    The ancient Egyptians left an impressive artistic legacy documenting many aspects of their society including the existence of dwarfs as highly valued members. In previous publications in the Journal, I discussed dwarfs and skeletal dysplasia in ancient Egypt. In this study, I examined the ancient Egyptian representations of dwarfs of the Walters Art Museum in Baltimore, Maryland. One of the highlights of the collection is a group of five ivory figurines from Predynastic Times (pre 3500-3100 BCE) depicting a couple, a man with a child, and two females. Representations from other periods include ordinary as well as dwarf deities. The dwarf gods, Bes and Ptah, are frequently depicted holding or biting snakes or standing on crocodiles symbolizing their ability to ward off dangers. A couple of statuettes from the Greco-Roman Period that, in contrast to earlier Egyptian Periods, depict harsh physical anomalies, twisted bodies, and facial pain. The artistic impression can be interpreted as either tragic or humorous. The grotesque depiction of dwarfs during the Greco-Roman Period in ancient Egypt is believed to be due to a greater infusion of Hellenistic influence. This study provides a microcosm of the legacy of dwarfs in ancient Egypt and supports the premise that dwarfs were accepted and integrated in the ancient Egyptian society, and with a few exceptions, their disorder was not depicted as a physical handicap.

  7. Mitogenomic analyses from ancient DNA

    DEFF Research Database (Denmark)

    Paijmans, Johanna L.A.; Gilbert, M Thomas P; Hofreiter, Michael

    2013-01-01

    analyses (whether using modern or ancient DNA) were largely restricted to the analysis of short fragments of the mitochondrial genome. However, due to many technological advances during the past decade, a growing number of studies have explored the power of complete mitochondrial genome sequences...... (mitogenomes). Such studies were initially limited to analyses of extant organisms, but developments in both DNA sequencing technologies and general methodological aspects related to working with degraded DNA have resulted in complete mitogenomes becoming increasingly popular for ancient DNA studies as well....... To date, at least 124 partially or fully assembled mitogenomes from more than 20 species have been obtained, and, given the rapid progress in sequencing technology, this number is likely to dramatically increase in the future. The increased information content offered by analysing full mitogenomes has...

  8. Molecular analysis of ancient caries.

    Science.gov (United States)

    Simón, Marc; Montiel, Rafael; Smerling, Andrea; Solórzano, Eduvigis; Díaz, Nancy; Álvarez-Sandoval, Brenda A; Jiménez-Marín, Andrea R; Malgosa, Assumpció

    2014-09-01

    An 84 base pair sequence of the Streptococcus mutans virulence factor, known as dextranase, has been obtained from 10 individuals from the Bronze Age to the Modern Era in Europe and from before and after the colonization in America. Modern samples show four polymorphic sites that have not been found in the ancient samples studied so far. The nucleotide and haplotype diversity of this region have increased over time, which could be reflecting the footprint of a population expansion. While this segment has apparently evolved according to neutral evolution, we have been able to detect one site that is under positive selection pressure both in present and past populations. This study is a first step to study the evolution of this microorganism, analysed using direct evidence obtained from ancient remains.

  9. Models of ancient sound vases

    Science.gov (United States)

    Bruel, Per V.

    2002-11-01

    Models were made of vases described by Vitruvius in Rome in about the year 70 A.D. and of sound vases (lydpotter) placed in Danish churches from 1100-1300 A.D. Measurements of vase's resonant frequencies and damping (reradiation) verified that the model vases obeyed expected physical rules. It was concluded that the excellent acoustical quality of many ancient Greek and Roman theaters cannot be ascribed to the vases placed under their seats. This study also found that sound vases placed in Nordic churches could not have shortened the reverberation time because there are far too few of them. Moreover, they could not have covered a broad frequency range. It remains a mystery why vases were installed under the seats of ancient Greek theaters and why, 1000 years later, Danes placed vases in their churches.

  10. Differences between the glacial cycles of Antarctic temperature and greenhouse gases

    Directory of Open Access Journals (Sweden)

    A. W. Omta

    2012-03-01

    Full Text Available Ice-core measurements have indicated that the atmospheric concentrations of the greenhouse gases CO2 and CH4 show glacial-interglacial variations in step with Antarctic temperature. To obtain more insight into the nature of this relationship for cycles of different frequencies, measured time series of temperature, CO2, and CH4 are reanalysed. The results indicate that the temperature signal consists of a linear superposition of a component related to CO2 with a period of ~100 000 yr and a component related to variations in the obliquity of the Earth's orbital plane with a period of ~41 000 yr. This suggests that either there operate very different feedback mechanisms at the different time scales or that CO2 is not merely a~passive follower and amplifier of the glacial-interglacial variations in Antarctic temperature.

  11. Splendid Arts Fram Ancient Capitals

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    IT was in the golden autumn in Beijing, when the sky was high and the air clear, that I hurried to Zhongshan Park to witness the display of the songs and dances of the seven Chinese ancient capitals. The flower beds arranged for the celebration of National Day were still there and the colorful blooms looked especially bright in the sunshine. The seven cities which have served as capitals in Chinese history are Beijing,

  12. Psychiatric Thoughts in Ancient India

    Directory of Open Access Journals (Sweden)

    Ravi Abhyankar

    2015-01-01

    Full Text Available A review of the literature regarding psychiatric thoughts in ancient India is attempted. Besides interesting reading, many of the concepts are still relevant and can be used in day-to-day practice especially towards healthy and happy living. Certain concepts are surprisingly contemporary and valid today. They can be used in psychotherapy and counselling and for promoting mental health. However, the description and classification of mental illness is not in tune with modern psychiatry.

  13. Nanoscience of an ancient pigment.

    Science.gov (United States)

    Johnson-McDaniel, Darrah; Barrett, Christopher A; Sharafi, Asma; Salguero, Tina T

    2013-02-06

    We describe monolayer nanosheets of calcium copper tetrasilicate, CaCuSi(4)O(10), which have strong near-IR luminescence and are amenable to solution processing methods. The facile exfoliation of bulk CaCuSi(4)O(10) into nanosheets is especially surprising in view of the long history of this material as the colored component of Egyptian blue, a well-known pigment from ancient times.

  14. Glacial-interglacial vegetation dynamics in south eastern Africa depend on sea surface temperature variations in the west Indian Ocean

    Directory of Open Access Journals (Sweden)

    L. M. Dupont

    2011-07-01

    Full Text Available Glacial-interglacial fluctuations in the vegetation of South Africa might elucidate the climate system at the edge of the tropics between Indian and Atlantic Ocean. However, vegetation records covering a full glacial cycle have only been published from the eastern South Atlantic. We present a pollen record of the marine core MD96-2048 retrieved by the Marion Dufresne from the Indian Ocean ~120 km south of the Limpopo River mouth. The sedimentation at the site is slow and continuous. The upper 6 m (down till 342 ka have been analysed for pollen and spores at millennial resolution. The terrestrial pollen assemblages indicate that during interglacials the vegetation of eastern South Africa and southern Mozambique largely consisted of evergreen and deciduous forests. During glacials open mountainous scrubland dominated. Montane forest with Podocarpus extended during humid periods favoured by strong local insolation. Correlation with the sea surface temperature record of the same core indicates that the extension of mountainous scrubland primarily depends on sea surface temperatures of the Agulhas Current. Our record corroborates terrestrial evidence of the extension of open mountainous scrubland (including elements with affinity to the Cape Flora for the last glacial as well as for other glacial periods of the past 300 ka.

  15. Solar Forcing of Greenland Climate during the Last Glacial Maximum

    Science.gov (United States)

    Adolphi, Florian; Muscheler, Raimund; Svensson, Anders; Aldahan, Ala; Possnert, Göran; Beer, Juerg; Sjolte, Jesper; Björck, Svante

    2014-05-01

    The role of solar forcing in climate changes is a matter of continuous debate. Challenges arise from the short period of direct observations of total solar irradiance (TSI), which indicate minor TSI variations of approximately 1 ‰ over an 11-year cycle, and the limited understanding of possible feedback mechanisms. Opposed to this, there is evidence from paleoclimate records for a tight coupling of solar activity and regional climate (e.g., Bond et al. 2001, Martin-Puertas et al. 2012). One proposed mechanism to amplify the Sun's influence on climate involves the relatively large modulation of the solar UV output (Haigh et al. 2010). This alters the radiative balance in the stratosphere via ozone feedback processes and eventually propagates downwards causing changes in the tropospheric circulation (Inesson et al. 2011). The regional response to this forcing may, however, also depend on orbital forcing of the mean state of the atmosphere (Dietrich et al. 2012). Prior to direct observations cosmogenic radionuclides such as 10Be and 14C are the most reliable proxies of solar activity. Their atmospheric production rates depend on the flux of galactic cosmic rays into the atmosphere which in turn is modulated by the strength of the Earth's and the solar magnetic fields. However, archives of 10Be and 14C are additionally affected by changes of their respective geochemical environment. Owing to their fundamentally different geochemistry, a combined analysis of 10Be and 14C records can aid to isolate production rate variations more reliably and thus, lead to improved reconstructions of solar variability. Due to the absence of high-quality high-resolution data this approach has so far been limited to the Holocene. We will present the first solar activity reconstruction for the end of the last glacial (22.5 - 10 ka BP) based on the cosmogenic radionuclides 10Be and 14C. We will compare glacial solar activity variations to Holocene features through combined interpretation

  16. The impact of the North American glacial topography on the evolution of the Eurasian ice sheet over the last glacial cycle

    Science.gov (United States)

    Liakka, Johan; Löfverström, Marcus; Colleoni, Florence

    2016-05-01

    Modeling studies have shown that the continental-scale ice sheets in North America and Eurasia in the last glacial cycle had a large influence on the atmospheric circulation and thus yielded a climate distinctly different from the present. However, to what extent the two ice sheets influenced each others' growth trajectories remains largely unexplored. In this study we investigate how an ice sheet in North America influences the downstream evolution of the Eurasian ice sheet, using a thermomechanical ice-sheet model forced by climate data from atmospheric snapshot experiments of three distinctly different phases of the last glacial cycle: the Marine Isotope Stages 5b, 4, and 2 (Last Glacial Maximum - LGM). Owing to the large uncertainty associated with glacial changes in the Atlantic meridional overturning circulation, each atmospheric snapshot experiment was conducted using two distinctly different ocean heat transport representations. Our results suggest that changes in the North American paleo-topography may have largely controlled the zonal distribution of the Eurasian ice sheet. In the MIS4 and LGM experiments, the Eurasian ice sheet migrates westward towards the Atlantic sector - largely consistent with geological data and contemporary ice-sheet reconstructions - due to a low wave number stationary wave response, which yields a cooling in Europe and a warming in northeastern Siberia. The expansion of the North American ice sheet between MIS4 and the LGM amplifies the Siberian warm anomaly, which limits the glaciation there and may therefore help explain the progressive westward migration of the Eurasian ice sheet in this time period. The ocean heat transport only has a small influence on the stationary wave response to the North American glacial topography; however, because temperature anomalies have a smaller influence on an ice sheet's ablation in a colder climate than in a warmer one, the impact of the North American glacial topography on the Eurasian ice

  17. Late-glacial of southern South America

    Science.gov (United States)

    Heusser, C. J.

    Overall trends in late-glacial paleoenvironments of southern South America are interpretable from the pollen stratigraphy of radiocarbon dated sections of mires in Tierra del Fuego (55°S), the Chilotan archipelago (42-43°S), and the Chilean Lake District (39-41°S). In Tierra del Fuego, southern beech ( Nothofagus) and shrub and herb taxa (Gramineae, Empetrum, Acaena, Gunnera, Compositae and Cyperaceae) serve as indicators of the changing climate; in the Chilotan archipelago and in the Chilean Lake District, southern beech and other trees (species of Myrtaceae, Podocarpus, Prumnopitys, Pseudopanax and Weinmannia) suffice as indices of climatic change. Pollen records from each of these regions, although in need of greater dating control, indicate climatic sequences that are broadly similar. The records, however, are not regionally consistent in all aspects and differ in their indicator value with the implication of fossil beetle evidence. Attempts at correlation can be unsatisfactory at times and can stem inter alia from the different ecophysiological responses of both plants and beetles to environmental pressures. These differences, which affect the timing of reproduction and migration, may result in the variable occurrence of different species in the records. The broad implication of the pollen data is that following a glacial readvance culminating at about 15,000-14,500 BP, late-glacial climate was generally warmer during intervals before 13,000 and between 12,000 and 11,000 BP, and was cooler between 13,000 and 12,000 and from 11,000 to 10,000 BP.

  18. Mapping The Ancient Maya Landscape From Space

    Science.gov (United States)

    Sever, Tom; Arnold, James E. (Technical Monitor)

    2002-01-01

    The Peten region of northern Guatemala is one of the last places on earth where major archeological sites remain to be discovered. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper and IKONOS satellite and airborne Star3-I radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as cities, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the bajos, which are seasonally flooded swamps that cover over 40% of the land surface. The use of bajos for farming has been a source of debate within the professional community for many years. But the recent detection and verification of cultural features within the bajo system by our research team are providing conclusive evidence that the ancient Maya had adapted well to wetland environments from the earliest times and utilized them until the time of the Maya collapse. The use of the bajos for farming is also an important resource for the future of the current inhabitants who are experiencing rapid population growth. Remote sensing imagery is also demonstrating that in the Preclassic period (600 BC- AD 250), the Maya had already achieved a high organizational level as evidenced by the construction of massive temples and an elaborate inter-connecting roadway system. Although they experienced several setbacks such as droughts and hurricanes, the Maya nevertheless managed the delicate forest ecosystem successfully for several centuries. However, around AD 800, something happened to the Maya to cause their rapid decline and eventual disappearance from the region. The evidence indicates that at this time there was increased climatic dryness, extensive deforestation, overpopulation, and widespread warfare. This raises a question that

  19. Reconstruction of Last Glacial to early Holocene monsoon variability from relict lake sediments of the Higher Central Himalaya, Uttrakhand, India

    DEFF Research Database (Denmark)

    Juyal, N.; Pant, R.K.; Basavaiah, N.

    2009-01-01

    correspondence at the millennial scale between our data and that of continental and marine records from the Indian sub-continent suggests that Goting basin responded to periods of strengthened monsoon during the Last Glacial to early Holocene. We attribute the millennial scale monsoon variability to climatic...

  20. Use of Glacial Fronts by Narwhals (Monodon monoceros) in West Greenland

    Science.gov (United States)

    Laidre, K. L.

    2015-12-01

    Glacial fronts in Greenland are known to be important summer habitat for narwhals (Monodon monoceros), as freshwater runoff and sediment discharge may aggregate prey at the terminus. We investigated the importance of glacial habitat characteristics in determining narwhal visitation. Narwhals (n=18) were instrumented with satellite transmitters in September 1993-1994 and 2006-2007 in Melville Bay, West Greenland. Daily narwhal locations were interpolated using a correlated random walk based on observed filtered locations and associated positional error. We also compiled a database on physical features of 41 glaciers along the northwest Greenland coast. This covered the entire coastal region with narwhal activity. Parameters included glacier ice velocity (km/yr) from radar satellite data, glacier front advance and retreat, and glacier width (km) at the ice-ocean interface derived using front position data digitized from 20-100m resolution radar image mosaics and Landsat imagery. We also quantified relative volumes and extent of glacial ice discharge, thickness of the glacial ice at the terminus (m), and water depth at the terminus (m) from gravity and airborne radar data, sediment flux from satellite-based analysis, and freshwater runoff from a regional atmospheric climate model (RACMO2.3). We quantified whale visits to glaciers at three distances (5, 7, and 10 km) and conducted proximity analyses on annual and monthly time steps. We estimated 1) narwhal presence or absence, 2) the number of 24 h periods spent at glaciers, and 3) the fraction of study animals that visited each glacier. The use of glacial habitat by narwhals expanded to the north and south between the 1990s (n=9 unique glaciers visited) and the 2000s (n=30 visited), likely due to loss of summer fast ice and later fall freeze-up trends (3.5 weeks later since 1979). We used a generalized linear mixed effects framework to quantify the glacier and fjord habitat characteristics preferred by narwhals.

  1. Testing the "Mudball Earth" Hypothesis: Are Neoproterozoic Glacial Deposits Capped with Supraglacial Dust?

    Science.gov (United States)

    Goodman, J. C.; Alvim Lage, C.

    2014-12-01

    The Snowball Earth hypothesis has inspired several variants which may help to explain some of the great mysteries of the Neoproterozoic glaciations. One of these, the "Mudball Earth", proposes that as the Earth remained completely frozen for millions of years, a layer of dust accumulated on the ice surface. This dust layer would darken the planet, making it easier for the Earth to escape from the highly stable snowball climate state. This hypothesis is testable: after the ice melted at the end of a glacial era, this dust would sink to the bottom of the ocean, possibly forming a distinct clay, mud, or silt layer on the top of the glacial till deposits: this "clay drape" would then be covered by the cap carbonates that mark a return to warm climate. Sublimation and ice flow during the glacial episode should make this layer thicker at the equator and thinner or absent in the poles. Is this clay layer actually present in the rock record? Is it more prevalent at the paleoequator, as predicted? A clay drape has been noticed anecdotally, but no global survey has been done to date. We conducted a thorough literature review of all sites where Neoproterozoic glacial diamictites have been observed, identifying the type of rock that lies between the diamictite and the postglacial cap carbonate, when present, during both Sturtian and Marinoan glacial periods. Only a few publications identify a distinct clay/silt/mud layer that might represent weathered dust. These sites are not grouped by paleolatitude in any obvious way. With access only to published reports, we cannot determine whether such a layer is absent, went unreported, or was misinterpreted by us. With this work we hope to attract the attention of Neoproterozoic field geologists, inviting them to comment on the presence or absence of strata which could confirm or reject the "Mudball" hypothesis.

  2. Impact of the oceanic geothermal heat flux on a glacial ocean state

    Science.gov (United States)

    Ballarotta, M.; Roquet, F.; Falahat, S.; Zhang, Q.; Madec, G.

    2015-08-01

    The oceanic geothermal heating (OGH) has a significant impact on the present-day ocean state, but its role during glacial periods, when the ocean circulation and stratification were different from those of today, remains poorly known. In the present study, we analyzed the response of the glacial ocean to OGH, by comparing ocean simulations of the Last Glacial Maximum (LGM, ∼ 21 ka ago) including or not geothermal heating. We found that applying the OGH warmed the Antarctic Bottom Waters (AABW) by ∼ 0.4 °C and increased the abyssal circulation by 15 to 30 % north of 30° S in the deep Pacific and Atlantic basins. The geothermally heated deep waters were then advected toward the Southern Ocean where they upwelled to the surface due to the Ekman transport. The extra heat transport towards Antarctica acted to reduce the amount of sea ice contributing to the freshening of the whole AABW overturning cell. The global amount of salt being conserved, this bottom freshening induced a salinification of the North Atlantic and North Pacific surface and intermediate waters, contributing to the deepening of the North Atlantic Deep Water. This indirect mechanism is responsible for the largest observed warming, found in the North Atlantic deep western boundary current between 2000 and 3000 m (up to 2 °C). The characteristic time scale of the ocean response to the OGH corresponds to an advective time scale (associated with the overturning of the AABW cell) rather than a diffusive time scale. The OGH might facilitate the transition from a glacial to an inter-glacial state but its effect on the deep stratification seems insufficient to drive alone an abrupt climate change.

  3. Glacial geology of the Shingobee River headwaters area, north-central Minnesota

    Science.gov (United States)

    Melchior, Robert C.

    2014-01-01

    During middle and late Wisconsin time in the Shingobee River headwaters area, the Laurentide Wadena lobe, Hewitt and Itasca phases, produced terminal and ground moraine along with a variety of associated glacial features. The stratigraphic record is accessible and provides details of depositional mode as well as principal glacial events during the advance and retreat of middle and late Wisconsin ice tongues. Geomorphic features such as tunnel valleys, stream terraces, and postglacial stream cuts formed by erosional events persist to the present day. Middle Wisconsin Hewitt phase deposits are the oldest and include drumlins, ground moraine, boulder pavements, and outwash. Together, these deposits suggest a wet-based, periodically surging glacier in a subpolar thermal state. Regional permafrost and deposition from retreating ice are inferred between the end of the Hewitt phase and the advance of late Wisconsin Itasca phase ice. Itasca phase glaciation occurred as a contemporaneous pair of adjacent ice tongues whose contrasting moraine styles suggest independent flow modes. The western (Shingobee) portion of the Itasca moraine contains composite ridges, permafrost phenomena, hill-hole pairs, and debris flows. By contrast, eastern (Onigum) moraine deposits generally lack glaciotectonic features and consist almost exclusively of mud and debris flows. Near the end of the Itasca phase, large-scale hill-hole pairs developed in the Shingobee division, and debris flows from the Onigum division blocked the preexisting Shingobee tunnel valley to form glacial lake Willobee. Postglacial streams formed deep valleys as glacial lake Willobee catastrophically drained. Dates based on temperature trends in Greenland ice cores are proposed for prominent glacial events in the Shingobee area. This report proposes that Hewitt phase glaciation occurred between 27.2 and 23.6 kiloannum and Itasca phase glaciation between 22.8 and 14.7 kiloannum. Des Moines lobe (Younger Dryas) glaciation

  4. Glacial lakes in the Indian Himalayas--from an area-wide glacial lake inventory to on-site and modeling based risk assessment of critical glacial lakes.

    Science.gov (United States)

    Worni, Raphael; Huggel, Christian; Stoffel, Markus

    2013-12-01

    Glacial lake hazards and glacial lake distributions are investigated in many glaciated regions of the world, but comparably little attention has been given to these topics in the Indian Himalayas. In this study we present a first area-wide glacial lake inventory, including a qualitative classification at 251 glacial lakes >0.01 km(2). Lakes were detected in the five states spanning the Indian Himalayas, and lake distribution pattern and lake characteristics were found to differ significantly between regions. Three glacial lakes, from different geographic and climatic regions within the Indian Himalayas were then selected for a detailed risk assessment. Lake outburst probability, potential outburst magnitudes and associated damage were evaluated on the basis of high-resolution satellite imagery, field assessments and through the use of a dynamic model. The glacial lakes analyzed in the states of Jammu and Kashmir and Himachal Pradesh were found to present moderate risks to downstream villages, whereas the lake in Sikkim severely threatens downstream locations. At the study site in Sikkim, a dam breach could trigger drainage of ca. 16×10(6)m(3) water and generate maximum lake discharge of nearly 7000 m(3) s(-). The identification of critical glacial lakes in the Indian Himalayas and the detailed risk assessments at three specific sites allow prioritizing further investigations and help in the definition of risk reduction actions.

  5. [Medicine in ancient Mesopotamia - part 2].

    Science.gov (United States)

    Martins E Silva, J

    2010-01-01

    The second part embraces exclusively the main characteristics of the medicine in Ancient Mesopotamia, in its main facets: concept of disease, healers and practice. The disease was considered a divine punishment or resultant from a malign influence. Insofar, the medicine began by being preventive, by the use of appropriate amulets or by offerings or sacrifices intending to pacify those malign forces. The treatment of the generality of the diseases privileged the expulsion of those spirits and malign influences from the patient body, purifying it, which was done by the specific intervention of a approximately shipu (clergymanexorcist); not having results, the treatment was continued by the asû (practical healer) that appealed to a group of physical manipulations, limited surgical acts and the administration or application of prescriptions, resultants of the mixture of organic and inorganic substances. In case of failing, the patients (as well as common healthy individuals or rule leaders) could fall back upon a priest diviner (bârû) that, by examination of the organs of an animal especially sacrificed for, would give a final decision about the disease or the future. Besides this more occult facet, nourished in religious faiths and in the magic, the medicine of Ancient Mesopotamia included rational knowledge, certainly as the result of systematic patients observation and semiotic interpretation. From those observations and knowledge referred to the Sumerian period, carefully logged, refined and transmitted to the following generations, it was built a valuable group of texts with the description of symptoms, signs, diagnosis and prognostic of the most common diseases, still identifiable in the present.

  6. Role of Southern Ocean stratification in glacial atmospheric CO2 reduction

    Science.gov (United States)

    Kobayashi, H.; Oka, A.

    2014-12-01

    Paleoclimate proxy data at the glacial period shows high salinity of more than 37.0 psu in the deep South Atlantic. At the same time, data also indicate that the residence time of the water mass was more than 3000 years. These data implies that the stratification by salinity was stronger in the deep Southern Ocean (SO) in the Last Glacial Maximum (LGM). Previous studies using Ocean General Circulation Model (OGCM) fail to explain the low glacial atmospheric carbon dioxide (CO2) concentration at LGM. The reproducibility of salinity and water mass age is considered insufficient in these OGCMs, which may in turn affect the reproducibility of the atmospheric CO2concentration. In coarse-resolution OGCMs, The deep water is formed by unrealistic open-ocean deep convection in the SO. Considering these facts, we guessed previous studies using OGCM underestimated the salinity and water mass age at LGM. This study investigate the role of the enhanced stratification in the glacial SO on the variation of atmospheric CO2 concentration by using OGCM. In order to reproduce the recorded salinity of the deep water, relaxation of salinity toward value of recorded data is introduced in our OGCM simulations. It was found that deep water formation in East Antarctica is required for explaining the high salinity in the South Atlantic. In contrast, it is difficult to explain the glacial water mass age, even if we assume the situation vertical mixing is very weak in the SO. Contrary to previous estimate, the high salinity of the deep SO resulted in increase of Antarctic Bottom water (AABW) flow and decrease the residence time of carbon in the deep ocean, which increased atmospheric CO2 concentration. On the other hand, the weakening of the vertical mixing in the SO contributed to increase the vertical gradient of dissolved inorganic carbon (DIC), which decreased atmospheric CO2 concentration. Adding the contribution of the enhanced stratification in the glacial SO, we obtained larger

  7. Abrupt climate variability of eastern Anatolia vegetation during the last glacial

    Directory of Open Access Journals (Sweden)

    N. Pickarski

    2015-07-01

    Full Text Available Detailed analyses of the Lake Van pollen and stable oxygen isotope record allow the identification of millennial-scale vegetation and environmental changes in eastern Anatolia throughout the last glacial. The climate within the last glacial period (∼75–15 ka BP was cold and dry, with low arboreal pollen (AP levels. The driest and coldest period corresponds to Marine Isotope Stage (MIS 2 (∼28–14.5 ka BP dominated by the highest values of xerophytic steppe vegetation. Our high-resolution multi proxy record shows rapid expansions and contractions that mimic the stadial-interstadial pattern of the Dansgaard–Oeschger (DO events as recorded in the Greenland ice cores, and thus, provide a linkage to North Atlantic climate oscillations. Periods of reduced moisture availability characterized at Lake Van by enhanced xerophytic species correlates well with increase in ice-rafted debris (IRD and a decrease of sea surface temperature (SST in the North Atlantic. Furthermore, comparison with the marine realm reveals that the complex atmosphere–ocean interaction can be recognized by the strength and position of the westerlies in eastern Anatolia. Influenced by rough topography at Lake Van, the expansion of temperate species (e.g. deciduous Quercus was stronger during interstadials DO 19, 17–16, 14, 12 and 8. However, Heinrich events (HE, characterized by highest concentrations of ice-rafted debris in marine sediments, are identified in eastern Anatolia by AP values not lower and high steppe components not more abundant than during DO stadials. In addition, this work is a first attempt to establish a continuous microscopic charcoal record over the last glacial in the Near East, which documents an initial immediate response to millennial-scale climate and environmental variability and enables the shed light on the history of fire activity during the last glacial.

  8. Mount Baker lahars and debris flows, ancient, modern, and future

    Science.gov (United States)

    Tucker, David S; Scott, Kevin M.; Grossman, Eric E.; Linneman, Scott

    2014-01-01

    The Middle Fork Nooksack River drains the southwestern slopes of the active Mount Baker stratovolcano in northwest Washington State. The river enters Bellingham Bay at a growing delta 98 km to the west. Various types of debris flows have descended the river, generated by volcano collapse or eruption (lahars), glacial outburst floods, and moraine landslides. Initial deposition of sediment during debris flows occurs on the order of minutes to a few hours. Long-lasting, down-valley transport of sediment, all the way to the delta, occurs over a period of decades, and affects fish habitat, flood risk, gravel mining, and drinking water.

  9. Glacial CO2 Cycles: A Composite Scenario

    Science.gov (United States)

    Broecker, W. S.

    2015-12-01

    There are three main contributors to the glacial drawdown of atmospheric CO2 content: starvation of the supply of carbon to the ocean-atmosphere reservoir, excess CO2 storage in the deep sea, and surface-ocean cooling. In this talk, I explore a scenario in which all three play significant roles. Key to this scenario is the assumption that deep ocean storage is related to the extent of nutrient stratification of the deep Atlantic. The stronger this stratification, the larger the storage of respiration CO2. Further, it is my contention that the link between Milankovitch insolation cycles and climate is reorganizations of the ocean's thermohaline circulation leading to changes in the deep ocean's CO2 storage. If this is the case, the deep Atlantic d13C record kept in benthic foraminifera shells tells us that deep ocean CO2 storage follows Northern Hemisphere summer insolation cycles and thus lacks the downward ramp so prominent in the records of sea level, benthic 18O and CO2. Rather, the ramp is created by the damping of planetary CO2 emissions during glacial time intervals. As it is premature to present a specific scenario, I provide an example as to how these three contributors might be combined. As their magnitudes and shapes remain largely unconstrained, the intent of this exercise is to provoke creative thinking.

  10. Geothermal activity helps life survive glacial cycles.

    Science.gov (United States)

    Fraser, Ceridwen I; Terauds, Aleks; Smellie, John; Convey, Peter; Chown, Steven L

    2014-04-15

    Climate change has played a critical role in the evolution and structure of Earth's biodiversity. Geothermal activity, which can maintain ice-free terrain in glaciated regions, provides a tantalizing solution to the question of how diverse life can survive glaciations. No comprehensive assessment of this "geothermal glacial refugia" hypothesis has yet been undertaken, but Antarctica provides a unique setting for doing so. The continent has experienced repeated glaciations that most models indicate blanketed the continent in ice, yet many Antarctic species appear to have evolved in almost total isolation for millions of years, and hence must have persisted in situ throughout. How could terrestrial species have survived extreme glaciation events on the continent? Under a hypothesis of geothermal glacial refugia and subsequent recolonization of nongeothermal regions, we would expect to find greater contemporary diversity close to geothermal sites than in nongeothermal regions, and significant nestedness by distance of this diversity. We used spatial modeling approaches and the most comprehensive, validated terrestrial biodiversity dataset yet created for Antarctica to assess spatial patterns of diversity on the continent. Models clearly support our hypothesis, indicating that geothermally active regions have played a key role in structuring biodiversity patterns in Antarctica. These results provide critical insights into the evolutionary importance of geothermal refugia and the history of Antarctic species.

  11. Rapid climate variability during warm and cold periods in polar regions and Europe

    DEFF Research Database (Denmark)

    Masson-Delmotte, V.; Landais, A.; Combourieu-Nebout, N.;

    2005-01-01

    Typical rapid climate events punctuating the last glacial period in Greenland, Europe and Antarctica are compared to two rapid events occurring under warmer conditions: (i) Dansgaard-Oeschger event 25, the first abrupt warming occurring during last glacial inception; (ii) 8.2 ka BP event, the onl...

  12. From Here I Walked into Ancient China

    Institute of Scientific and Technical Information of China (English)

    Yan Manman

    2011-01-01

    @@ When I was a little girl, I had heard about the eighth world wonder - terra cotta warriors in Qin Emperor Mausoleum.I have been wishing to visit there to see those magnificent scene which were created thousands of years ago.While with my age added, I gradually learned the terra cotta warriors were lust only one of many ancient marks of Xi'an, which once was capital of 13 dynasties in ancient China.Xi'an actually is a carrier of ancient China culture, where I walked from the modern world to the ancient China.

  13. Ancient Indian Leaps into Mathematics

    CERN Document Server

    Yadav, B S

    2011-01-01

    This book presents contributions of mathematicians covering topics from ancient India, placing them in the broader context of the history of mathematics. Although the translations of some Sanskrit mathematical texts are available in the literature, Indian contributions are rarely presented in major Western historical works. Yet some of the well-known and universally-accepted discoveries from India, including the concept of zero and the decimal representation of numbers, have made lasting contributions to the foundation of modern mathematics. Through a systematic approach, this book examines th

  14. Chinese Ancient Football with Romanticism

    Institute of Scientific and Technical Information of China (English)

    江凌; 李晓勤

    2004-01-01

    Like other traditional Chinese sports, the ancient Chinese football, which used to be called “cuju”, has some differences from several sports in western countries concerning cultural and hamanist purport as well as metal aspiration, although it was similar with modern football to some extent, such as a leather-made ball with a bladder, rectangle sports ground, referee, goal and certain competitiveness. The author tries to talk about such difference in cultural and humanist purport as well as mental aspiration by making a comparison between “cuju” and modern football.

  15. Amazonian mid- to high-latitude glaciation on Mars: Supply-limited ice sources, ice accumulation patterns, and concentric crater fill glacial flow and ice sequestration

    Science.gov (United States)

    Fastook, James L.; Head, James W.

    2014-02-01

    Crater deposit thicknesses (~50 m) cannot fill the craters in a time period compatible with the interpreted formation times of the Pedestal Crater mantled ice layers. We use a representative obliquity solution to drive an ice flow model and show that a cyclical pattern of multiply recurring layers can both fill the craters with a significant volume of ice, as well as transport debris from the crater walls out into the central regions of the craters. The cyclical pattern of waxing and waning mantling layers results in a rippled pattern of surface debris extending out into the crater interiors that would manifest itself as an observable concentric pattern, comparable in appearance to concentric crater fill. In this scenario, the formation of mantling sublimation till layers seals the accumulating ice and sequesters it from significant temperature variations at diurnal, annual and spin-axis/orbital cycle time scales, to produce ancient ice records preserved today below CCF crater floors. Lack of meltwater features associated with concentric crater fill provides evidence that the Late Amazonian climate did not exceed the melting temperature in the mid- to high-latitudes for any significant period of time. Continued sequestration of ice with time in CCF and related deposits (lobate debris aprons and lineated valley fill) further reduces the already supply-limited polar ice sources, suggesting that there has been a declining reservoir of available ice with each ensuing glacial period. Together, these deposits represent a candidate library of climate chemistry and global change dating from the Late Amazonian, and a non-polar water resource for future exploration.

  16. Simulation of long-term future climate changes with the green McGill paleoclimate model. The next glacial inception

    Energy Technology Data Exchange (ETDEWEB)

    Cochelin, A.S.B.; Mysak, L.A.; Wang, Zhaomin Wang [Department of Atmospheric and Oceanic Sciences, McGill University, 805 Sherbrooke Street West, Montreal, Quebec H3A 2K6 (Canada)

    2006-12-15

    The multi-component 'green' McGill Paleoclimate Model (MPM), which includes interactive vegetation, is used to simulate the next glacial inception under orbital and prescribed atmospheric CO2 forcing. This intermediate complexity model is first run for short-term periods with an increasing atmospheric CO2 concentration; the model's response is in general agreement with the results of GCMs for CO2 doubling. The green MPM is then used to derive projections of the climate for the next 100 kyr. Under a constant CO2 level, the model produces three types of evolution for the ice volume: an imminent glacial inception (low CO2 levels), a glacial inception in 50 kyr (CO2 levels of 280 or 290 ppm), or no glacial inception during the next 100 kyr (CO2 levels of 300 ppm and higher). This high sensitivity to the CO2 level is due to the exceptionally weak future variations of the summer insolation at high northern latitudes. The changes in vegetation re-inforce the buildup of ice sheets after glacial inception. Finally, if an initial global warming episode of finite duration is included, after which the atmospheric CO2 level is assumed to stabilize at 280, 290 or 300 ppm, the impact of this warming is seen only in the first 5 kyr of the run; after this time the response is insensitive to the early warming perturbation.

  17. Light attenuation characteristics of glacially-fed lakes

    Science.gov (United States)

    Rose, Kevin C.; Hamilton, David P.; Williamson, Craig E.; McBride, Chris G.; Fischer, Janet M.; Olson, Mark H.; Saros, Jasmine E.; Allan, Mathew G.; Cabrol, Nathalie

    2014-07-01

    Transparency is a fundamental characteristic of aquatic ecosystems and is highly responsive to changes in climate and land use. The transparency of glacially-fed lakes may be a particularly sensitive sentinel characteristic of these changes. However, little is known about the relative contributions of glacial flour versus other factors affecting light attenuation in these lakes. We sampled 18 glacially-fed lakes in Chile, New Zealand, and the U.S. and Canadian Rocky Mountains to characterize how dissolved absorption, algal biomass (approximated by chlorophyll a), water, and glacial flour contributed to attenuation of ultraviolet radiation (UVR) and photosynthetically active radiation (PAR, 400-700 nm). Variation in attenuation across lakes was related to turbidity, which we used as a proxy for the concentration of glacial flour. Turbidity-specific diffuse attenuation coefficients increased with decreasing wavelength and distance from glaciers. Regional differences in turbidity-specific diffuse attenuation coefficients were observed in short UVR wavelengths (305 and 320 nm) but not at longer UVR wavelengths (380 nm) or PAR. Dissolved absorption coefficients, which are closely correlated with diffuse attenuation coefficients in most non-glacially-fed lakes, represented only about one quarter of diffuse attenuation coefficients in study lakes here, whereas glacial flour contributed about two thirds across UVR and PAR. Understanding the optical characteristics of substances that regulate light attenuation in glacially-fed lakes will help elucidate the signals that these systems provide of broader environmental changes and forecast the effects of climate change on these aquatic ecosystems.

  18. Post glacial rebounds measure the viscosity of the lithosphere

    CERN Document Server

    Garai, J

    2003-01-01

    The observed higher uplift rates before the end of deglaciation requires the existence of a low viscosity channel or layer. The uplifts observed after the end of deglaciation does not show any contribution from this low viscosity channel and a homogeneous viscosity model fits very well to the observed uplift. Most of the researchers therefore prefer the homogeneous model and suggest that the higher uplift rate before the end of deglaciation is the result of elastic contamination. It has been shown that the elastic deformation of the lithosphere is far too small to be responsible for the observed extra uplift; therefore, the homogeneous viscosity model should be discredited. The homogeneous viscosity of the postglacial period and the high uplift rate of the late glacial period can be explained with a model which has an upper layer determining the homogeneous viscosity and the layer below it which has a low viscosity. The contribution to the uplift of this low viscosity layer is indistinguishable from an instan...

  19. Astronomical forcing and mathematical theory of glacial-interglacial cycles

    Directory of Open Access Journals (Sweden)

    A. V. Kislov

    2009-02-01

    Full Text Available There are three important features of a proxy time series recorded during the Late Pleistocene. They are: 1 100 000-year cycle as a dominant control of global glacial-interglacials through the late Quaternary, 2 fluctuations with periods of about 40 and 20 thousand years (their contribution to dispersion is no more than 20%, 3 ''Red-noise'' behavior of the time series. Direct influence of the insolation change created by fluctuations of the eccentricity is too weak to cause the observed 100 000-year climate fluctuations. Therefore, other mechanisms of such a rhythm are proposed. On the basis of the equation of the heat budget, the equation describing dynamics of zonally averaged temperature is developed. Various combinations of terms of this equation are discussed. They present a linear response to the Milankovitch periodicity, the Langeven stochastic equation, the equation of delay oscillator, the stochastic equation of spontaneous transitions, and the equation of stochastic resonance.

    Orbitally-induced changes in the solar energy flux received by the Earth play an important role as a mechanism starting process of climate changes which is supported and intensified by different feedbacks within the climate system. Positive anomalies of solar radiation serve as a mechanism causing reorganization of the climate only in rare cases when inclination of Earth axis of rotation increases and, simultaneously, perihelion takes place during the summer time (for the Northern Hemisphere.

  20. Foreign Guests in Ancient Greece

    Directory of Open Access Journals (Sweden)

    Zora Žbontar

    2013-12-01

    Full Text Available Xenía was a special relationship between a foreign guest and his host in Ancient Greece. The ritual of hosting a foreigner included an exchange of objects, feasting, and the establishment of friendship between people from different social backgrounds. This relationship implied trust, loyalty, friendship, and mutual aid between the people involved. Goods and services were also exchanged without any form of payment. There were no formal laws governing xenía – it was based entirely on a moral appeal. Mutual appreciation between the host and the guest was established during the ritual, but the host did retain a certain level of superiority over the guest. Xenía was one of the most important institutions in Ancient Greece. It had a lot of features and obligations similar to kinship and marriage. In literary sources the word xénos varies in meaning from “enemy stranger”, “friendly stranger”, “foreigner”, “guest”, “host” to “ritual friend”, and it is often hard to tell which usage is appropriate in a given passage. The paper describes the emphasis on hospitality towards foreigners. It presents an example of a depiction indicating xenía is presented, as well as several objects which were traded during the ritual. The paper also addresses the importance of hospitality in Greek drama in general, especially with examples of violations of the hospitality code.

  1. [Ancient history of Indian pharmacy].

    Science.gov (United States)

    Okuda, Jun; Natsume, Yohko

    2010-01-01

    The study of the ancient history of Indian medicine has recently been revived due to the publication of polyglot translations. However, little is known of ancient Indian pharmacy. Archaeological evidence suggests the Indus people lived a settled life approximately in 2500 B.C. Their cities were enjoying the cleanest and most hygienic daily life with elaborate civic sanitation systems. The whole conception shows a remarkable concern for health. Then, the early Aryans invaded India about 1500 B.C. and the Vedic age started. The Rgveda texts contain the hymns for Soma and those for herbs. The term Ayurveda (i.e., science of life) is found in some old versions of both Ramāyana and Mahābhārata and in the Atharvaveda. Suśruta had the credit of making a breakthrough in the field of surgery. The Ayurveda, a work on internal medicine, gives the following transmission of sages: Brahmā-->Daksa-->Prajāpati-->Aśivinau-->Indra-->Caraka. On the other hand, the Suśruta-samhitā, which deals mainly with surgical medicine, explains it as follows; Indra-->Dhanvantari-->Suśruta Both Caraka and Suśruta were medical doctors as well as pharmacists, so they studied more than 1000 herbs thoroughly. The Ayurveda had been used by his devotees for medical purposes. It eventually spread over Asia with the advanced evolution of Buddhism.

  2. Variations of organic carbon isotopic composition and its environmental significance during the last glacial on western Chinese Loess Plateau

    Institute of Scientific and Technical Information of China (English)

    CHEN Fahu; RAO Zhiguo; ZHANG Jiawu; JIN Ming; MA Jianying

    2006-01-01

    A high-resolution loess section in the western Chinese Loess Plateau, Yuanbao Section,was sampled for organic carbon isotopic analyses.The soil organic carbon isotope (δ13Corg) varied between -22.6‰ and -27.5‰ during the last glacial at the section. During the last interstadial, the δ13Corg values were more negative than those in both early and late periods of the last glacial by 4‰. The isotopic composition indicates a coupled response of the pure C3 plants to the temperature, precipitation and the concentration of atmospheric CO2. Decrease in temperature and the atmospheric CO2 concentration from the last interstadial to Last Glaicial Maximum (LGM) caused the organic carbon isotopes to become positive by 1.5‰-2.0‰. The amplitude of 4‰in the δ13Corg variation during the last glacial should be mainly caused by the precipitation change.Therefore, the δ13Corg variations of the Yuanbao Section during the last glacial period documented the large-amplitude fluctuation of the monsoon precipitation, which is estimated to be 250-310 mm more during the last interstadial than that in the LGM, and 100 mm more than that during early last glacial. The rapid changes of the monsoon precipitation on millennial scale during the last glacial have also been recorded in the isotopic variations in Yuanbao loess section. As the isotopic composition varies complicatedly as shown in the Ioess-paleosol sequence, it cannot be simply attributed to the abundances of C3and C4 plants or be used as an indicator of the summer monsoon variations.

  3. 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

    Energy Technology Data Exchange (ETDEWEB)

    Landstroem, Ove [Studsvik Eco and Safety AB, Nykoeping (Sweden); Tullborg, Eva-Lena [Terralogica AB, Graabo (Sweden); Eriksson, Gunda; Sandell, Yvonne [Studsvik Nuclear AB, Nykoeping (Sweden)

    2001-08-01

    in slight dissolution of these minerals. Quartz and K-feldspar have remained almost unaltered. Besides the thin weathered surface rim, slight alteration of plagioclase and increase in porosity is indicated in the 2-3 cm zone below the surface. Decrease of U and Cs concentrations in this zone is then interpreted as being due to leaching/diffusion processes, confined to the Weichselian glaciation (< 100 ka). The 234U/238U is close to unity indicating bulk leaching of U under oxic conditions. The deposition of U in Ya 1192 and leaching of U from BAS 1 are coeval to quaternary glacial, interstadial and interglacial periods during which the hydrogeological and geochemical conditions changed significantly. A main question in performance assessment is whether oxygenated glacial meltwater can penetrate to repository depth (500 m) and modify the redox conditions. The bedrock surface at BAS 1 has certainly been in contact with glacial meltwater as well as meteoric water, resulting in oxidation/ alteration of pyrite, oxidation/mobilisation of U, and probably also desorption/ mobilisation of Cs. In contrast, no signs of oxygenated glacial meltwater influence were found in the YA 1192 core (170 m depth). In fact, the absence of Fe oxyhydroxide but presence of fresh pyrite in the fracture filling and the altered zone at YA 1192 as well as deposition of U are contradictory to interactions with oxidising glacial meltwater from the late glaciations.

  4. The breast: from Ancient Greek myths to Hippocrates and Galen.

    Science.gov (United States)

    Iavazzo, C R; Trompoukis, C; Siempos, I I; Falagas, M E

    2009-01-01

    This is a historical article about Ancient Greek literature from mythological times until the first centuries AD with regard to the female breast. We endeavoured to collect several elegant narratives on the topic as well as to explore the knowledge of Ancient Greek doctors on the role, physiology and pathology of breast and the treatment of its diseases. We identified such descriptions in myths regarding Amazons, Hercules, Zeus, Hera and Amaltheia. Furthermore, descriptions on the topic were also found in the work of Hippocrates, Aristoteles, Soranos, Alexander of Aphrodisias, Celsus, Archigenis, Leonides, Galen and Oribasius. We may conclude that some of today's medical knowledge or practice regarding the breast was also known in the historical period.

  5. Genome-wide patterns of selection in 230 ancient Eurasians

    Science.gov (United States)

    Mathieson, Iain; Lazaridis, Iosif; Rohland, Nadin; Mallick, Swapan; Patterson, Nick; Roodenberg, Songül Alpaslan; Harney, Eadaoin; Stewardson, Kristin; Fernandes, Daniel; Novak, Mario; Sirak, Kendra; Gamba, Cristina; Jones, Eppie R.; Llamas, Bastien; Dryomov, Stanislav; Pickrel, Joseph; Arsuaga, Juan Luís; de Castro, José María Bermúdez; Carbonell, Eudald; Gerritsen, Fokke; Khokhlov, Aleksandr; Kuznetsov, Pavel; Lozano, Marina; Meller, Harald; Mochalov, Oleg; Moiseyev, Vayacheslav; Rojo Guerra, Manuel A.; Roodenberg, Jacob; Vergès, Josep Maria; Krause, Johannes; Cooper, Alan; Alt, Kurt W.; Brown, Dorcas; Anthony, David; Lalueza-Fox, Carles; Haak, Wolfgang; Pinhasi, Ron; Reich, David

    2016-01-01

    Ancient DNA makes it possible to directly witness natural selection by analyzing samples from populations before, during and after adaptation events. Here we report the first scan for selection using ancient DNA, capitalizing on the largest genome-wide dataset yet assembled: 230 West Eurasians dating to between 6500 and 1000 BCE, including 163 with newly reported data. The new samples include the first genome-wide data from the Anatolian Neolithic culture whose genetic material we extracted from the DNA-rich petrous bone and who we show were members of the population that was the source of Europe’s first farmers. We also report a complete transect of the steppe region in Samara between 5500 and 1200 BCE that allows us to recognize admixture from at least two external sources into steppe populations during this period. We detect selection at loci associated with diet, pigmentation and immunity, and two independent episodes of selection on height. PMID:26595274

  6. Ideas of Physical Forces and Differential Calculus in Ancient India

    CERN Document Server

    Girish, T E

    2011-01-01

    We have studied the context and development of the ideas of physical forces and differential calculus in ancient India by studying relevant literature related to both astrology and astronomy since pre-Greek periods. The concept of Naisargika Bala (natural force) discussed in Hora texts from India is defined to be proportional to planetary size and inversely related to planetary distance. This idea developed several centuries prior to Isaac Newton resembles fundamental physical forces in nature especially gravity. We show that the studies on retrograde motion and Chesta Bala of planets like Mars in the context of astrology lead to development of differential calculus and planetary dynamics in ancient India. The idea of instantaneous velocity was first developed during the 1st millennium BC and Indians could solve first order differential equations as early as 6th cent AD. Indian contributions to astrophysics and calculus during European dark ages can be considered as a land mark in the pre-renaissance history ...

  7. Spectral analysis of pharmaceutical formulations prepared according to ancient recipes in comparison with old museum remains.

    Science.gov (United States)

    Gamberini, M Cristina; Baraldi, C; Freguglia, G; Baraldi, P

    2011-10-01

    A study of the composition of the remains of ancient ointments from museums was undertaken to enable understanding of the preparation techniques. Comparison of ancient recipes from different historical periods and spectroscopic characteristics of inorganic and/or organic remains recovered in museum vessels enabled preparation of ancient pharmaceutical-cosmetic formulations. Farmacopea Augustana by Occo was one the most important books studied for the 14 formulations prepared in the laboratory. Three formulations are discussed in detail and raw materials and new preparations were proposed for ozone ageing. The most important micro Raman results are discussed. The spectra of the raw materials lipids, beeswax, and resins are discussed; beeswax and pig suet (axŭngia) Raman spectra were found to be similar, but different from those of the aged oils. SERS was applied to ancient ointments and galbanum and the Raman spectra are reported and discussed for the first time.

  8. Dust deposition in Antarctica in glacial and interglacial climate conditions: a modelling study

    Directory of Open Access Journals (Sweden)

    N. Sudarchikova

    2014-09-01

    Full Text Available The mineral dust cycle responds to climate variations and plays an important role in the climate system by affecting the radiative balance of the atmosphere and modifying biogeochemistry. Polar ice cores provide a unique information about deposition of aeolian dust particles transported over long distance. These cores are a paleoclimate proxy archive of climate variability thousands of years ago. The current study is a first attempt to simulate past interglacial dust cycles with a global aerosol-climate model ECHAM5-HAM. The results are used to explain the dust deposition changes in Antarctica in terms of quantitative contribution of different processes, such as emission, atmospheric transport and precipitation, which will help to interpret paleodata from Antarctic ice cores. The investigated periods include four interglacial time-slices such as the pre-industrial control (CTRL, mid-Holocene (6000 yr BP, last glacial inception (115 000 yr BP and Eemian (126 000 yr BP. One glacial time interval, which is Last Glacial Maximum (LGM (21 000 yr BP was simulated as well as to be a reference test for the model. Results suggest an increase of mineral dust deposition globally, and in Antarctica, in the past interglacial periods relative to the pre-industrial CTRL simulation. Approximately two thirds of the increase in the mid-Holocene and Eemian is attributed to enhanced Southern Hemisphere dust emissions. Slightly strengthened transport efficiency causes the remaining one third of the increase in dust deposition. The moderate change of dust deposition in Antarctica in the last glacial inception period is caused by the slightly stronger poleward atmospheric transport efficiency compared to the pre-industrial. Maximum dust deposition in Antarctica was simulated for the glacial period. LGM dust deposition in Antarctica is substantially increased due to 2.6 times higher Southern Hemisphere dust emissions, two times stronger atmospheric transport towards

  9. Modelling of mineral dust for interglacial and glacial climate conditions with a focus on Antarctica

    Directory of Open Access Journals (Sweden)

    N. Sudarchikova

    2015-05-01

    Full Text Available The mineral dust cycle responds to climate variations and plays an important role in the climate system by affecting the radiative balance of the atmosphere and modifying biogeochemistry. Polar ice cores provide unique information about deposition of aeolian dust particles transported over long distances. These cores are a palaeoclimate proxy archive of climate variability thousands of years ago. The current study is a first attempt to simulate past interglacial dust cycles with a global aerosol–climate model ECHAM5-HAM. The results are used to explain the dust deposition changes in Antarctica in terms of quantitative contribution of different processes, such as emission, atmospheric transport and precipitation, which will help to interpret palaeodata from Antarctic ice cores. The investigated periods include four interglacial time slices: the pre-industrial control (CTRL, mid-Holocene (6000 yr BP; hereafter referred to as "6 kyr", last glacial inception (115 000 yr BP; hereafter "115 kyr" and Eemian (126 000 yr BP; hereafter "126 kyr". One glacial time interval, the Last Glacial Maximum (LGM (21 000 yr BP; hereafter "21 kyr", was simulated as well to be a reference test for the model. Results suggest an increase in mineral dust deposition globally, and in Antarctica, in the past interglacial periods relative to the pre-industrial CTRL simulation. Approximately two-thirds of the increase in the mid-Holocene and Eemian is attributed to enhanced Southern Hemisphere dust emissions. Slightly strengthened transport efficiency causes the remaining one-third of the increase in dust deposition. The moderate change in dust deposition in Antarctica in the last glacial inception period is caused by the slightly stronger poleward atmospheric transport efficiency compared to the pre-industrial. Maximum dust deposition in Antarctica was simulated for the glacial period. LGM dust deposition in Antarctica is substantially increased due to 2.6 times higher

  10. Characteristics of Soil Fertility of Buried Ancient Paddy at Chuodun Site in Yangtze River Delta, China

    Institute of Scientific and Technical Information of China (English)

    LU Jia; HU Zheng-yi; CAO Zhi-hong; YANG Lin-zhang; LIN Xian-gui; DONG Yuan-hua; DING Jin-long; ZHENG Yun-fei

    2006-01-01

    Field investigation and laboratory analysis of 22 ancient paddy soils excavated at Chuodun site, Kunshan City, JiangsuProvince, China were carried out in 2003 to (1) understand the basic characteristics of ancient paddy soils, (2) compare the difference of soil fertility between ancient paddy soils and recent paddy soils, and (3) inquire into mechanisms of the sustainability of paddy soil. The oldest paddy soils at Chuodun site can be dated back to Neolithic age, around 6 000 aBP. These ancient fields were buried in about 1-m deep from the soil surface and their areas ranged from 0.32 to 12.9 m2 with an average of 5.2 m2. The paddy soils with > 5 000 pellets phytolith g-1 soil were termed intensively cultivated paddy soils (ICPS) and those with < 5 000 pellets phytolith g-1 soil were called weakly cultivated soils (WCPS). The contents of organic carbon (OC), and total N in the former were significantly higher than that in the latter. Ancient paddy soils had higher soil pH and C/N, total and available P, and lower contents of OC, DOC, total N, S, Cu, Fe, and available K, S, Fe, Mn, and Cu compared with recent paddy soils, which were attributed to application of chemical and manure fertilizers, pollution and acidification in recent paddy soils. The variation coefficients of OC and other nutrients in ancient paddy soils with higher PI were greater than that in ancient paddy soils with low PI, which indicated that human activities had a great impact on the spatial variability of soil nutrients. The contents of OC, total N, P and S in ancient paddy soils were higher than that in ancient moss of the same age, which indicated that planting rice during Majiabang culture period was beneficial to the accumulation of those life elements.

  11. Sensitivity simulations with direct shortwave radiative forcing by aeolian dust during glacial cycles

    Science.gov (United States)

    Bauer, E.; Ganopolski, A.

    2014-07-01

    Possible feedback effects between aeolian dust, climate and ice sheets are studied for the first time with an Earth system model of intermediate complexity over the late Pleistocene period. Correlations between climate and dust deposition records suggest that aeolian dust potentially plays an important role for the evolution of glacial cycles. Here climatic effects from the dust direct radiative forcing (DRF) caused by absorption and scattering of solar radiation are investigated. Key elements controlling the dust DRF are the atmospheric dust distribution and the absorption-scattering efficiency of dust aerosols. Effective physical parameters in the description of these elements are varied within uncertainty ranges known from available data and detailed model studies. Although the parameters can be reasonably constrained, the simulated dust DRF spans a~wide uncertainty range related to the strong nonlinearity of the Earth system. In our simulations, the dust DRF is highly localized. Medium-range parameters result in negative DRF of several watts per square metre in regions close to major dust sources and negligible values elsewhere. In the case of high absorption efficiency, the local dust DRF can reach positive values and the global mean DRF can be insignificantly small. In the case of low absorption efficiency, the dust DRF can produce a significant global cooling in glacial periods, which leads to a doubling of the maximum glacial ice volume relative to the case with small dust DRF. DRF-induced temperature and precipitation changes can either be attenuated or amplified through a feedback loop involving the dust cycle. The sensitivity experiments suggest that depending on dust optical parameters, dust DRF has the potential to either damp or reinforce glacial-interglacial climate changes.

  12. Sensitivity simulations with direct radiative forcing by aeolian dust during glacial cycles

    Science.gov (United States)

    Bauer, E.; Ganopolski, A.

    2014-01-01

    Possible feedback effects between aeolian dust, climate and ice sheets are studied for the first time with an Earth system model of intermediate complexity over the late Pleistocene period. Correlations between climate variables and dust deposits suggest that aeolian dust potentially plays an important role for the evolution of glacial cycles. Here climatic effects from the dust direct radiative forcing (DRF) caused by absorption and scattering of solar radiation are investigated. Key factors controlling the dust DRF are the atmospheric dust distribution and the absorption-scattering efficiency of dust aerosols. Effective physical parameters in the description of these factors are varied within uncertainty ranges known from available data and detailed model studies. Although the parameters are reasonably constrained by use of these studies, the simulated dust DRF spans a wide uncertainty range related to nonlinear dependencies. In our simulations, the dust DRF is highly localized. Medium-range parameters result in negative DRF of several W m-2 in regions close to major dust sources and negligible values elsewhere. In case of high absorption efficiency, the local dust DRF can reach positive values and the global mean DRF can be insignificantly small. In case of low absorption efficiency, the dust DRF can produce a significant global cooling in glacial periods which leads to a doubling of the maximum glacial ice volume relative to the case with small dust DRF. DRF-induced temperature and precipitation changes can either be attenuated or amplified through a feedback loop involving the dust cycle. The sensitivity experiments suggest that depending on dust optical parameters the DRF has the potential to either damp or reinforce glacial-interglacial climate changes.

  13. A simple metabolic model of glacial-interglacial energy supply to the upper ocean

    Directory of Open Access Journals (Sweden)

    J. L. Pelegrí

    2011-03-01

    Full Text Available We use a simple two-state two-box ocean to simulate the CO2 signal during the last four glacial-interglacial transitions in the earth system. The model is inspired by the similarity in spatial organization and temporal transition patterns between the earth and other complex systems, such as mammals. The comparison identifies the earth's metabolic rate with net autotrophic primary production in the upper ocean, sustained through new inorganic carbon and nutrients advected from the deep ocean and organic matter remineralized within the upper ocean. We view the glacial-interglacial transition as a switch of the upper ocean from a basal to an enhanced metabolic state, with energy supply initially relying on the remineralization of the local organic sources and the eventual steady state resulting from the increased advective supply of inorganic deep sources. During the interglacial-glacial transition the opposite occurs, with an initial excess of advective supply and primary production that allows the replenishment of the upper-ocean organic storages. We set the relative change in energy supply from the CO2 signal and use genetic algorithms to explore the sensitivity of the model output to both the basal recirculation rate and the intensity-timing of the maximum recirculation rate. The model is capable of reproducing quite well the long-term oscillations, as shown by correlations with observations typically about 0.8. The dominant time scale for each cycle ranges between about 40 and 45 kyr, close to the 41 kyr average obliquity astronomical period, and the deep-ocean recirculation rate increases between one and two orders of magnitude from glacial to interglacial periods.

  14. Enhanced North Atlantic deep convection preceding Heinrich 1 glacial ice sheet destabilization

    Science.gov (United States)

    Seidenkrantz, Marit-Solveig; Kuijpers, Antoon; Lindgreen, Holger

    2015-04-01

    The Labrador Sea is a crucial center of action for North Atlantic meridional overturning circulation. This region is characterized in winter by strong cold and dry winds from land or ice surfaces inducing large heat and moisture fluxes at the ocean-atmosphere interface. Particularly in late winter these conditions favor deep-convection processes leading to the formation of a relatively homogeneous and oxygen-rich intermediate water mass (Labrador Sea Water, LSW) spreading to other parts of the North Atlantic at water depths between about 1,000 and 2,000 m. Sedimentary records from the Labrador Sea have previously indicated here the presence of North Atlantic Deep Water during periods in between glacial ('Heinrich') ice-rafting events. The present sediment core investigation based on clay mineralogical analysis and study of the benthic foraminiferal fauna shows a significant oxygenation event at 18000 cal.yrs BP recorded both in the Labrador Sea and at the northern margin of Rockall Trough at 2381 m and 1286 m water depth, respectively. We conclude this ventilation pulse to be related to a period of enhanced deep convection and formation of glacial North Atlantic Intermediate Water occupying those parts of the water column presently affected under conditions of strong LSW formation. This ventilation event implies an early, significant re-activation of North Atlantic meridional overturning circulation after the Last Glacial Maximum immediately prior to Heinrich 1 large-scale ice-sheet destabilization. This scenario points to an oceanic trigger mechanism for large-scale glacial iceberg surges around the northern North Atlantic, which involves enhanced northward ocean (sub)surface heat transport and subsequent enhanced bottom melting of floating outlet glaciers and ice shelves.

  15. 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

  16. 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.

  17. Wind Stress Increases Glacial Atlantic Overturning

    Science.gov (United States)

    Muglia, J.; Schmittner, A.

    2015-12-01

    Previous Paleoclimate Model Intercomparison Project (PMIP) simulations of the Last Glacial Maximum (LGM) Atlantic Meridional Overturning Circulation (AMOC) showed ambiguous results on transports and structure. Here we analyze the most recent PMIP3 models, which show a consistent increase (on average by 41%) and deepening (580 m) of the AMOC for all models with respect to pre-industrial control (PIC) simulations (see Figure), in contrast to some reconstructions. Changes in wind stress alone lead to similar AMOC responses in a climate-ocean circulation model, suggesting that atmospheric circulation changes in the North Atlantic due to the presence of ice sheets are an important control in the PMIP3 models' LGM response. These results improve our understanding of the LGM AMOC's driving forces and are relevant for the evaluation of models that are used in the IPCC's Assessment Reports for future climate projections, as well as for the currently ongoing design of the next round of PMIP.

  18. δ13Ccarb and Ceanom excursions in the post-glacial Neoproterozoic and Early Cambrian interval in Guizhou,South China

    Institute of Scientific and Technical Information of China (English)

    FENG Hongzhen; LING Hongfei; JIANG Shaoyong; YANG Jinghong

    2004-01-01

    Secular δ 13Ccarb and Ceanom profiles in the post-glacial Neoproterozoic and Early Cambrian interval are reported from Guizhou on the southeasten border of the Yangtze platform, South China. Overall, the δ 13Ccarb profile drifts to negative values in the post-glacial Nantuo and lower to middle Doushantuo Formations, and then to positive values in the upper Doushantuo and Dengying Formations of Neoproterozoic, followed by negative values in the Lower Cambrian Gezhongwu and Niutitang Formations. A detailed investigation of the relationship between the δ 13Ccarb and Ceanom profiles reveals that the main anoxic and oxic episodes are coupled with negative and positive δ 13Ccarb values, respectively. This may suggest a control of alternation between ocean stratification and mixing on variations in 13C abundance in the ancient ocean of the investigated areas.

  19. Attitudes Toward Deviant Sex in Ancient Mesopotamia

    Science.gov (United States)

    Bullough, Vern L.

    1971-01-01

    The article concludes that the whole question of sexual life in ancient Mesopotamia is difficult to reconstruct and fraught with many uncertainties. Nevertheless, it seems certain that the ancient Mesopotamians had fewer prohibitions against sex than our own civilization, and regarded as acceptable many practices which later societies condemned.…

  20. Women--Sex Objects in Ancient Egypt.

    Science.gov (United States)

    Mutimer, Brian T. P.

    Although it has been said that the women in Ancient Egypt enjoyed a reasonable state of social and professional equality with men, this paper presents an alternate theory--that women were second-class citizens whose physical prowess was secondary to their role as sex objects. It appears that men and women in Ancient Egypt often participated in the…

  1. The Idea of Ancient Greek Philosophy

    Institute of Scientific and Technical Information of China (English)

    苏雪

    2016-01-01

    As the source of western philosophy, ancient Greek philosophy had a profound influence on western philosophy. Ancient philosophers were hard to reach a consensus on the existence of all the things in the world. They tried to grasp the profound understanding of the world, which is the clue of the history of philosophy.

  2. Numerical simulation of Glacial Isostatic Adjustment

    Science.gov (United States)

    Miglio, E.

    2015-12-01

    In the Earth's crust, stress can be subdivided into tectonic background stress, overburden pressure, and pore-fluid pressure. The superposition of the first two and the variation of the third part are key factors in controlling movement along faults. Furthermore, stresses due to sedimentation and erosion contribute to the total stress field. In deglaciated regions, an additional stress must be considered: the rebound stress, which is related to rebounding of the crust and mantle after deglaciation. During the growth of a continental ice sheet, the lithosphere under the iceload is deformed and the removal of the ice load during deglaciation initiates a rebound process. The uplift is well known in formerly glaciated areas, e.g.North America and Scandinavia, and in currently deglaciating areas, e.g.Alaska, Antarctica, and Greenland. The whole process of subsiding and uplifting during the growth and melting of an iceload and all related phenomena is known as glacial isostatic adjustment. During the process of glaciation, the surface of the lithosphere is depressed underneath the ice load and compressional flexural stresses are induced in the upper lithosphere, whereas the bottom of the lithosphere experiences extensional flexural stresses; an additional vertical stress due to the ice load is present and it decreases to zero during deglaciation. During rebound, flexural stresses relax slowly. These stresses are able to change the original stress directions and regime.In this work we aim to study the effect of the GIA process in the context of petroleum engineering. The main aspect we will focus on is the mathematical and numerical modeling of the GIA including thermal effects. We plan also to include a preliminary study of the effect of the glacial erosion. All these phenomena are of paramount importance in petroleum engineering: for example some reservoir have been depleted due to tilting caused by both GIA, erosion and thermal effects.

  3. Estimating the volume of Alpine glacial lakes

    Science.gov (United States)

    Cook, S. J.; Quincey, D. J.

    2015-12-01

    Supraglacial, moraine-dammed and ice-dammed lakes represent a potential glacial lake outburst flood (GLOF) threat to downstream communities in many mountain regions. This has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery. Such relationships are based on the notion that lake depth, area and volume scale predictably. We critically evaluate the performance of these existing empirical relationships by examining a global database of glacial lake depths, areas and volumes. Results show that lake area and depth are not always well correlated (r2 = 0.38) and that although lake volume and area are well correlated (r2 = 0.91), and indeed are auto-correlated, there are distinct outliers in the data set. These outliers represent situations where it may not be appropriate to apply existing empirical relationships to predict lake volume and include growing supraglacial lakes, glaciers that recede into basins with complex overdeepened morphologies or that have been deepened by intense erosion and lakes formed where glaciers advance across and block a main trunk valley. We use the compiled data set to develop a conceptual model of how the volumes of supraglacial ponds and lakes, moraine-dammed lakes and ice-dammed lakes should be expected to evolve with increasing area. Although a large amount of bathymetric data exist for moraine-dammed and ice-dammed lakes, we suggest that further measurements of growing supraglacial ponds and lakes are needed to better understand their development.

  4. Structural recognition of ancient Chinese ideographic characters

    Institute of Scientific and Technical Information of China (English)

    Li Ning; Chen Dan

    2014-01-01

    Ancient Chinese characters, typically the ideographic characters on bones and bronze before Shang Dynasty (16th—11th century B.C.), are valuable culture legacy of history. However the recognition of Ancient Chinese characters has been the task of paleography experts for long. With the help of modern computer technique, everyone can expect to be able to recognize the characters and understand the ancient inscriptions. This research is aimed to help people recognize and understand those ancient Chinese characters by combining Chinese paleography theory and computer information processing technology. Based on the analysis of ancient character features, a method for structural character recognition is proposed. The important characteristics of strokes and basic components or radicals used in recognition are introduced in detail. A system was implemented based on above method to show the effectiveness of the method.

  5. Detecting hybridization using ancient DNA.

    Science.gov (United States)

    Schaefer, Nathan K; Shapiro, Beth; Green, Richard E

    2016-06-01

    It is well established that related species hybridize and that this can have varied but significant effects on speciation and environmental adaptation. It should therefore come as no surprise that hybridization is not limited to species that are alive today. In the last several decades, advances in technologies for recovering and sequencing DNA from fossil remains have enabled the assembly of high-coverage genome sequences for a growing diversity of organisms, including many that are extinct. Thanks to the development of new statistical approaches for detecting and quantifying admixture from genomic data, genomes from extinct populations have proven useful both in revealing previously unknown hybridization events and informing the study of hybridization between living organisms. Here, we review some of the key recent statistical innovations for detecting ancient hybridization using genomewide sequence data and discuss how these innovations have revised our understanding of human evolutionary history.

  6. [Being old in ancient Hellas].

    Science.gov (United States)

    van Hooff, A J

    1983-08-01

    There is room for a more balanced view of old age among the ancient Greeks than is furnished by De Beauvoir's la Vieillesse and other more or less one-sided publications. The old body was despised by the Greeks of classical times; especially walking with three legs (tripous) was stressed as a mark of old age. The Hippocratic writings show some interest in the infirmities of elderly people. Specific psychic and intellectual qualities were not attributed to senescence: old age brought out good and bad qualities of a person more sharply than before. The share of old people in the population cannot be established with any certainty, but there was always a group of men in their sixties who had specific tasks in society. Old age was not an autonomous theme in art, it was solely accidental. The position of the elderly was challenged occasionally in democratic Athens, but it was never undermined. Old people were never marginated in classical Greece.

  7. Ancient Acupuncture Literature on Apoplexy

    Institute of Scientific and Technical Information of China (English)

    XU Yi-zeng; BI Zhen; Xiao Yuan-chun

    2003-01-01

    This paper reviews twenty-eight Chinese medicine books with complete prescriptions prior to the Qing Dynasty, and analyzes the characteristics of acupoint selection and needling manipulations from the perspective of apoplectic symptoms. It is concluded that,in ancient times, apoplexy is often treated on the basis of its symptoms and a great number of acupoints are employed; hemiplegia is mainly treated by the acupoints of the Large Intestine Meridian and Gallbladder Meridian,with two key acupoints; coma is mainly treated by first-aid acupoints and qi-supplementing acupoints, with seven key acupoints; wry mouth and convulsion are mainly treated by the local acupoints; as for needling manipulations, moxibustion with moxa cones is principally used, while needling is less used.

  8. Glacial and periglacial buzzsaws: fitting mechanisms to metaphors

    Science.gov (United States)

    Hall, Adrian M.; Kleman, Johan

    2014-03-01

    The buzzsaw hypothesis refers to the potential for glacial and periglacial processes to rapidly denude mountains at and above glacier Equilibrium Line Altitudes (ELAs), irrespective of uplift rates, rock type or pre-existing topography. Here the appropriateness of the buzzsaw metaphor is examined alongside questions of the links between glacial erosion and ELAs, and whether the glacial system can produce low-relief surfaces or limit summit heights. Plateau fragments in mountains on both active orogens and passive margins that have been cited as products of glacial and periglacial buzzsaw erosion instead generally represent dissected remnants of largely inherited, pre-glacial relief. Summit heights may correlate with ELAs but no causal link need be implied as summit erosion rates are low, cirque headwalls may not directly abut summits and, on passive margins, cirques are cut into pre-existing mountain topography. Any simple links between ELAs and glacial erosion break down on passive margins due to topographic forcing of ice-sheet growth, and to the km-scale vertical swaths through which ELAs have shifted through the Quaternary. Glaciers destroy rather than create low-relief rock surfaces through the innate tendency for ice flow to be faster, thicker and warmer along valleys. The glacial buzzsaw cuts down.

  9. Fire in Ice: Glacial-Interglacial biomass burning in the NEEM ice core

    Science.gov (United States)

    Zennaro, Piero; Kehrwald, Natalie; Zangrando, Roberta; Gambaro, Andrea; Barbante, Carlo

    2014-05-01

    shift of taiga may have reduced the levoglucosan flux over Greenland during the Glacial, thus limiting the biomass burning signatures in the glacial NEEM section. Eemian biomass burning would be expected to be greater than that of the last Glacial due to incresed temperatures and the lack of continental ice sheets. However, NEEM Eemian levoglucosan concentrations are unexpectedly low, and are lower than any other climate period including the last Glacial. We propose that microbial activity in melting ice layers is a potential explanation for the low observed Eemian levoglucosan values.

  10. Cases of Trephination in Ancient Greek Skulls

    Directory of Open Access Journals (Sweden)

    Vasiliki Ζafiri

    2012-01-01

    Full Text Available Background: Trephination, or trepanning, is considered to be one of the most ancient surgical operations with an especially extensive geographical incidence, both in the New World and in the Old. In Europe, more than 200 finds of trephination have been found, from Scandinavia to the Balkans. The technique of trephination or trepanning covers overall the last 10,000 years and exhibits great versatility and adjustability in the knowledge, technical means, therapeutic needs, prejudices and social standards of each period and of each population group. Hippocrates was the one to classify for the first time the kinds of cranial fractures and define the conditions and circumstances for carrying out a trepanning.Aim: The present research aims to investigate the Greek cranial trephinations on sculls from the collection of the Anthropological Museum of the Medical School of Athens that come from archaeological excavations.Method: Skulls were examined by macroscopic observation with reflective light. Furthermore, radiographic representation of the skulls was used.Results: The anthropological researches and the studies of anthropological skeleton remains that came out during archaeological excavations from different eras and areas have given information about the medical practices in the very important geographic area of Greece and in particular, we referred to cases of Greek trephinations.

  11. The Last Glacial Maximum experiment in PMIP4-CMIP6

    Science.gov (United States)

    Kageyama, Masa; Braconnot, Pascale; Abe-Ouchi, Ayako; Harrison, Sandy; Lambert, Fabrice; Peltier, W. Richard; Tarasov, Lev

    2016-04-01

    The Last Glacial Maximum (LGM), around 21,000 years ago, is a cold climate extreme. As such, it has been the focus of many studies on modelling and climate reconstruction, which have brought knowledge on the mechanisms explaining this climate, in terms of climate on the continents and of the ocean state, and in terms relationships between climate changes over land, ice sheets and oceans. It is still a challenge for climate or Earth System models to represent the amplitude of climate changes for this period, under the following forcings: - Ice sheets, which represent perturbations in land surface type, altitude and land/ocean distribution - Atmospheric composition - Astronomical parameters Feedbacks from the vegetation and dust are also known to have played a role in setting up the LGM climate but have not been accounted for in previous PMIP experiments. In this poster, we will present the experimental set-up of the PMIP4 LGM experiment, which is presently being discussed and will be finalized for March 2016. For more information and discussion of the PMIP4-CMIP6 experimental design, please visit: https://wiki.lsce.ipsl.fr/pmip3/doku.php/pmip3:cmip6:design:index

  12. Inland post-glacial dispersal in East Asia revealed by mitochondrial haplogroup M9a'b

    Directory of Open Access Journals (Sweden)

    Wang Wen-Zhi

    2011-01-01

    Full Text Available Abstract Background Archaeological studies have revealed a series of cultural changes around the Last Glacial Maximum in East Asia; whether these changes left any signatures in the gene pool of East Asians remains poorly indicated. To achieve deeper insights into the demographic history of modern humans in East Asia around the Last Glacial Maximum, we extensively analyzed mitochondrial DNA haplogroup M9a'b, a specific haplogroup that was suggested to have some potential for tracing the migration around the Last Glacial Maximum in East Eurasia. Results A total of 837 M9a'b mitochondrial DNAs (583 from the literature, while the remaining 254 were newly collected in this study pinpointed from over 28,000 subjects residing across East Eurasia were studied here. Fifty-nine representative samples were further selected for total mitochondrial DNA sequencing so we could better understand the phylogeny within M9a'b. Based on the updated phylogeny, an extensive phylogeographic analysis was carried out to reveal the differentiation of haplogroup M9a'b and to reconstruct the dispersal histories. Conclusions Our results indicated that southern China and/or Southeast Asia likely served as the source of some post-Last Glacial Maximum dispersal(s. The detailed dissection of haplogroup M9a'b revealed the existence of an inland dispersal in mainland East Asia during the post-glacial period. It was this dispersal that expanded not only to western China but also to northeast India and the south Himalaya region. A similar phylogeographic distribution pattern was also observed for haplogroup F1c, thus substantiating our proposition. This inland post-glacial dispersal was in agreement with the spread of the Mesolithic culture originating in South China and northern Vietnam.

  13. Mitochondrial DNA signals of late glacial recolonization of Europe from near eastern refugia.

    Science.gov (United States)

    Pala, Maria; Olivieri, Anna; Achilli, Alessandro; Accetturo, Matteo; Metspalu, Ene; Reidla, Maere; Tamm, Erika; Karmin, Monika; Reisberg, Tuuli; Hooshiar Kashani, Baharak; Perego, Ugo A; Carossa, Valeria; Gandini, Francesca; Pereira, Joana B; Soares, Pedro; Angerhofer, Norman; Rychkov, Sergei; Al-Zahery, Nadia; Carelli, Valerio; Sanati, Mohammad Hossein; Houshmand, Massoud; Hatina, Jiři; Macaulay, Vincent; Pereira, Luísa; Woodward, Scott R; Davies, William; Gamble, Clive; Baird, Douglas; Semino, Ornella; Villems, Richard; Torroni, Antonio; Richards, Martin B

    2012-05-01

    Human populations, along with those of many other species, are thought to have contracted into a number of refuge areas at the height of the last Ice Age. European populations are believed to be, to a large extent, the descendants of the inhabitants of these refugia, and some extant mtDNA lineages can be traced to refugia in Franco-Cantabria (haplogroups H1, H3, V, and U5b1), the Italian Peninsula (U5b3), and the East European Plain (U4 and U5a). Parts of the Near East, such as the Levant, were also continuously inhabited throughout the Last Glacial Maximum, but unlike western and eastern Europe, no archaeological or genetic evidence for Late Glacial expansions into Europe from the Near East has hitherto been discovered. Here we report, on the basis of an enlarged whole-genome mitochondrial database, that a substantial, perhaps predominant, signal from mitochondrial haplogroups J and T, previously thought to have spread primarily from the Near East into Europe with the Neolithic population, may in fact reflect dispersals during the Late Glacial period, ∼19-12 thousand years (ka) ago.

  14. Enhanced subarctic Pacific stratification and nutrient utilization during glacials over the last 1.2 Myr

    Science.gov (United States)

    Knudson, Karla P.; Ravelo, Ana Christina

    2015-11-01

    The relationship between climate, biological productivity, and nutrient flux is of considerable interest in the subarctic Pacific, which represents an important high-nitrate, low-chlorophyll region. While previous studies suggest that changes in iron supply and/or physical ocean stratification could hypothetically explain orbital-scale fluctuations in subarctic Pacific nutrient utilization and productivity, previous records of nutrient utilization are too short to evaluate these relationships over many glacial-interglacial cycles. We present new, high-resolution records of sedimentary δ15N, which offer the first opportunity to evaluate systematic, orbital-scale variations in subarctic Pacific nitrate utilization from 1.2 Ma. Nitrate utilization was enhanced during all glacials, varied with orbital-scale periodicity since the mid-Pleistocene transition, was strongly correlated with enhanced aeolian dust and low atmospheric CO2, but was not correlated with productivity. These results suggest that glacial stratification, rather than iron fertilization, systematically exerted an important regional control on nutrient utilization and air-sea carbon flux.

  15. The role of orbital forcing, carbon dioxide and regolith in 100 kyr glacial cycles

    Directory of Open Access Journals (Sweden)

    A. Ganopolski

    2011-12-01

    Full Text Available The origin of the 100 kyr cyclicity, which dominates ice volume variations and other climate records over the past million years, remains debatable. Here, using a comprehensive Earth system model of intermediate complexity, we demonstrate that both strong 100 kyr periodicity in the ice volume variations and the timing of glacial terminations during past 800 kyr can be successfully simulated as direct, strongly nonlinear responses of the climate-cryosphere system to orbital forcing alone, if the atmospheric CO2 concentration stays below its typical interglacial value. The existence of long glacial cycles is primarily attributed to the North American ice sheet and requires the presence of a large continental area with exposed rocks. We show that the sharp, 100 kyr peak in the power spectrum of ice volume results from the long glacial cycles being synchronized with the Earth's orbital eccentricity. Although 100 kyr cyclicity can be simulated with a constant CO2 concentration, temporal variability in the CO2 concentration plays an important role in the amplification of the 100 kyr cycles.

  16. Oxygen depletion recorded in upper waters of the glacial Southern Ocean

    Science.gov (United States)

    Lu, Zunli; Hoogakker, Babette A. A.; Hillenbrand, Claus-Dieter; Zhou, Xiaoli; Thomas, Ellen; Gutchess, Kristina M.; Lu, Wanyi; Jones, Luke; Rickaby, Rosalind E. M.

    2016-01-01

    Oxygen depletion in the upper ocean is commonly associated with poor ventilation and storage of respired carbon, potentially linked to atmospheric CO2 levels. Iodine to calcium ratios (I/Ca) in recent planktonic foraminifera suggest that values less than ∼2.5 μmol mol−1 indicate the presence of O2-depleted water. Here we apply this proxy to estimate past dissolved oxygen concentrations in the near surface waters of the currently well-oxygenated Southern Ocean, which played a critical role in carbon sequestration during glacial times. A down-core planktonic I/Ca record from south of the Antarctic Polar Front (APF) suggests that minimum O2 concentrations in the upper ocean fell below 70 μmol kg−1 during the last two glacial periods, indicating persistent glacial O2 depletion at the heart of the carbon engine of the Earth's climate system. These new estimates of past ocean oxygenation variability may assist in resolving mechanisms responsible for the much-debated ice-age atmospheric CO2 decline. PMID:27029225

  17. [Medicine in ancient Mesopotamia--part 1].

    Science.gov (United States)

    Martins E Silva, J

    2009-01-01

    , would give a final decision about the disease or the future. Separated this more occult facet, nourished in religious faiths and in the magic, the medicine of Ancient Mesopotamia included rational knowledge, certainly as the result of a systematic patients observation and semiotic interpretation. From those observations and knowledge referred to the Sumerian period, carefully logged, refined and transmitted to the following generations, a valuable collection of texts was built with the description of symptoms, signs, diagnosis and prognostic of the most common diseases, still identifiable in the present.

  18. Factors controlling variability in the oxidative capacity of the troposphere since the Last Glacial Maximum

    Directory of Open Access Journals (Sweden)

    L. T. Murray

    2013-09-01

    Full Text Available The oxidative capacity of past atmospheres is highly uncertain. We present here a new climate-biosphere-chemistry modeling framework to determine oxidant levels in the present and past troposphere. We use the GEOS-Chem chemical transport model driven by meteorological fields from the NASA Goddard Institute of Space Studies (GISS ModelE, with land cover and fire emissions from dynamic global vegetation models. We present time-slice simulations for the present day, late preindustrial (AD 1770, and the Last Glacial Maximum (LGM; 19–23 ka, and we test the sensitivity of model results to uncertainty in lightning and fire emissions. We find that most preindustrial and paleo climate simulations yield reduced oxidant levels relative to the present day. Contrary to prior studies, tropospheric mean OH in our ensemble shows little change at the LGM relative to the preindustrial (0.5 ± 12%, despite large reductions in methane concentrations. We find a simple linear relationship between tropospheric mean ozone photolysis rates, water vapor, and total emissions of NOx and reactive carbon that explains 72% of the variability in global mean OH in 11 different simulations across the last glacial-interglacial time interval and the Industrial Era. Key parameters controlling the tropospheric oxidative capacity over glacial-interglacial periods include overhead stratospheric ozone, tropospheric water vapor, and lightning NOx emissions. Variability in global mean OH since the LGM is insensitive to fire emissions. Our simulations are broadly consistent with ice-core records of Δ17O in sulfate and nitrate at the LGM, and CO, HCHO, and H2O2 in the preindustrial. Our results imply that the glacial-interglacial changes in atmospheric methane observed in ice cores are predominantly driven by changes in its sources as opposed to its sink with OH.

  19. Reconstruction of Hydrologic Variability at Lake Elsinore, California, During the Late-Glacial to Holocene Transition

    Science.gov (United States)

    Fantozzi, J. M.; Bonuso, N.; Kirby, M. E.; Zimmerman, S. R.; Hiner, C.

    2011-12-01

    A multi-proxy sedimentological study was completed on a section of a sediment core from Lake Elsinore, California, that spans the late-Glacial to Holocene transition (17,619-9,587 calendar years before present [cy BP]). The results of the study provide the first high resolution terrestrial climate record from Southern California that spans this interesting interval in Earth's climate history. The sedimentological observations and proxy results indicate that the depositional and climatic environments of Lake Elsinore changed significantly across the late-Glacial to Holocene transition. Interpretation of the results suggests that the lake was relatively deep during the last glacial period, but then became relatively shallow and less stable near the beginning of the Holocene interglacial. Interpretation of the results also suggests that the Lake Elsinore deglaciation sequence was characterized by two step-wise decreases in precipitation. Here, this two step drying trend is explained by changes in the extent of the North American ice sheet and variations in the intensity of the Atlantic Meridional Overturning Circulation. Together, the latter two forcings acted to modulate the average position of the circumpolar jet stream, the mean latitude of the Intertropical Convergence Zone, and their combined impacts on the Northern Hemisphere winter storm tracks, which determine the annual hydrologic budget of Southern California. A comparison of the Lake Elsinore deglaciation sequence with other regional paleoclimate records shows strong evidence for synchronous hydrologic change between study sites throughout southwestern North America. Additionally, a comparison of the Lake Elsinore record with the Greenland ice core record provides evidence for a coupling between changes in climate over the North Atlantic and Southern California during the late-Glacial to Holocene transition.

  20. gargammel: a sequence simulator for ancient DNA.

    Science.gov (United States)

    Renaud, Gabriel; Hanghøj, Kristian; Willerslev, Eske; Orlando, Ludovic

    2016-10-29

    Ancient DNA has emerged as a remarkable tool to infer the history of extinct species and past populations. However, many of its characteristics, such as extensive fragmentation, damage and contamination, can influence downstream analyses. To help investigators measure how these could impact their analyses in silico, we have developed gargammel, a package that simulates ancient DNA fragments given a set of known reference genomes. Our package simulates the entire molecular process from post-mortem DNA fragmentation and DNA damage to experimental sequencing errors, and reproduces most common bias observed in ancient DNA datasets.

  1. Organic structure and possible origin of ancient charred paddies at Chuodun Site in southern China

    Institute of Scientific and Technical Information of China (English)

    HU LinChao; LI Xia; LIU BenDing; GU Min; DAI JingYu

    2009-01-01

    A number of ancient charred paddies with a 14C dating of about 5900 a BP were recovered in the sixthexcavation at Chuodun Site and are assigned to the Majiabang culture (7-6 ka BP). To understand their formation mechanism, the ancient charred paddies were compared to modern paddies using FT-IR spectrum and thermaogravimetric analysis. At the same time, modern charred paddies were made in helium by the laboratory method, and the structural characteristics of them and the ancient ones were revealed using CP/MAS-13C-NMR. Our results show there are more aromatic moieties in ancient charred paddies compared to modern paddies. The aliphatic components of modern charred paddies decreasecontinuously, accompanied by the accumulation of aromatic components, when the duration and temperature of oxidation increase, and the structure buildings of modern charred paddies are more similar to ancient ones. Given the planting manner of paddies during Majiabang culture period, these ancient charred paddies might be a result of the original farming mode involving fire.

  2. Organic structure and possible origin of ancient charred paddies at Chuodun Site in southern China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A number of ancient charred paddies with a 14C dating of about 5900 a BP were recovered in the sixth excavation at Chuodun Site and are assigned to the Majiabang culture(7-6 ka BP).To understand their formation mechanism,the ancient charred paddies were compared to modern paddies using FT-IR spectrum and thermaogravimetric analysis.At the same time,modern charred paddies were made in helium by the laboratory method,and the structural characteristics of them and the ancient ones were revealed using CP/MAS-13C-NMR.Our results show there are more aromatic moieties in ancient charred paddies compared to modern paddies.The aliphatic components of modern charred paddies decrease continuously,accompanied by the accumulation of aromatic components,when the duration and temperature of oxidation increase,and the structure buildings of modern charred paddies are more similar to ancient ones.Given the planting manner of paddies during Majiabang culture period,these ancient charred paddies might be a result of the original farming mode involving fire.

  3. Glacial Ridge National Wildlife Refuge : Annual Narrative Fiscal Year 2006

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Glacial Ridge National Wildlife Refuge summarizes Refuge activities during the 2006 fiscal year. The report begins with an...

  4. Aquifers of Alluvial and Glacial Origin - Direct Download

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the alluvial and glacial aquifers north of the southern-most line of glaciation. Aquifers are shown in the States of Maine,...

  5. Glacial Ridge National Wildlife Refuge : Annual Narrative Fiscal Year 2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Glacial Ridge National Wildlife Refuge summarizes Refuge activities during the 2005 fiscal year. The report begins with an...

  6. Precipitation Isotopes Reveal Intensified Indonesian Monsoon Circulation During the Dry Last Glacial Maximum

    Science.gov (United States)

    Konecky, B. L.; Russell, J. M.; Vogel, H.; Bijaksana, S.; Huang, Y.

    2014-12-01

    The Indo-Pacific Warm Pool (IPWP) invigorates the oceanic-atmospheric circulation in the tropics, with far-reaching climate impacts that extend into the high latitudes. A growing number of deglacial proxy reconstructions from the region have revealed the importance of both high- and low-latitude climate processes to IPWP rainfall during the late Pleistocene. Many of these proxies reconstruct the oxygen and hydrogen isotopic composition of rainfall (δ18Oprecip, δDprecip), a powerful tool for understanding changes in climate. However, an increasing number of studies from the region have highlighted the tendency for δ18Oprecip and δDprecip to reflect regional and/or remote circulation processes rather than local rainfall amounts, complicating the reconstruction of IPWP hydroclimate. To better understand high- and low-latitude drivers of late Pleistocene hydroclimate in the IPWP, precipitation isotopic reconstructions must be constrained with both modern observations and independent proxies for rainfall amount. We present a reconstruction of δDprecip using leaf wax compounds preserved in the sediments of Lake Towuti, Sulawesi, from 60,000 years before present to today. We interpret our proxy record with the aid of a new precipitation isotopic dataset from our study site, with daily rainfall isotope measurements to constrain the processes controlling δDprecip. Our Lake Towuti δDwax record is strikingly similar to a speleothem δ18O record from southern Indonesia (Ayliffe et al., 2013) and shares features with other nearby records spanning the Last Glacial Maximum to present. Together, these records indicate that monsoon circulation was intensified in central and southern Indonesia during the glacial period. However, other independent rainfall proxies from Lake Towuti indicate that dry conditions accompanied the intensified monsoon. Regional-scale isotopic depletion during the dry glacial period may have arisen from dynamical and other fractionating processes that

  7. Enigmatic sediment ridges in the German Bight - glacial vs post-glacial morphologies?

    Science.gov (United States)

    Unnithan, Vikram; Pio Rossi, Angelo; Praeg, Daniel

    2014-05-01

    The German Wadden Sea extends over 1000 km from the Dutch coast to that of Sweden and consists of a long chain of barrier islands and ephemeral sand banks punctuated by estuaries and rivers. The sedimentary environment is currently shaped and characterised by storm surges, high tidal and wave energy levels. However, this part of the North Sea has been repeatedly covered by continental ice sheets, and it remains unclear how glacial to interglacial sedimentary processes may have influenced seabed morphology in the region. The study area is situated approximately 70 km north of Cuxhaven, and 5 km due east of the islands of Helgoland and Dune. It covers an approximate area of 5 km square with water depths ranging from 50 m in the south to about 20 m in the north. High resolution multibeam (Simrad EM710) and parametric echosounder (Innomar SES2000) data were acquired during graduate and undergraduate teaching excursions on the RV Heincke in Spring 2010 (HE-324) and 2011 (HE-349). The seabed swath bathymetric data reveal distinctive linear seabed ridges. The ridges trend NNW-SSE, are 1-5 m in height, have wavelengths on the order of 100 m and crest lengths ranging from 100-2500 m. The ridge crests are broadly anastomosing. They bifurcate towards the north to form more subdued structures, while they converge and disappear to the south. Profiles across the ridges show an asymmetric structure, with steeper slopes trending west in the western part of the study area but trending east in the eastern part. These enigmatic sedimentary structures have not been previously mapped in the Wadden Sea, and their origin remains uncertain. Possible interpretations to be tested include sub-crop structural control on seabed morphology, relict glacial or glaciofluvial landforms and post-glacial marine bedforms linked to processes of sediment redistribution.

  8. Systematic Uncertainties of Glacial Chronologies Based on Surface Exposure Dating

    Science.gov (United States)

    Ilgner, J.; Zech, R.; Baechtiger, C.; Kubik, P. W.; Veit, H.

    2008-12-01

    Surface exposure dating using terrestrial cosmogenic nuclides provides the opportunity to establish glacial chronologies in semi-arid high mountain regions, where the lack of organic material for radiocarbon dating has limited our knowledge about the timing and the causes of glacial advances so far. However, several scaling systems and calculation schemes exist. This can result in significant systematic uncertainties, particularly at high altitudes as e.g. in the Central Andes. We present and discuss previously published exposure ages from Bolivia and Argentina in order to illustrate the extent of the current uncertainties. It is neither possible to unambiguously determine whether the local Last Glacial Maximum (local LGM) in the tropics occurred in-phase with or predated the global LGM, nor can the subsequent Late Glacial stages be dated accurately enough to infer temperature or precipitation changes at millennial-scale timescales. We then also present new results from the Tres Lagunas in the Sierra de Santa Victoria, NW Argentina. There we can compare our glacial exposure age chronology with bracketing radiocarbon ages from lake sediments. The Tres Lagunas may thus serve as a high-altitude calibration site for 10Be dating. Paleoclimatically, we conclude that glacial deposits in NW-Argentina document glacial advances in-phase with the global LGM, but that the prominent moraines there date to the Late Glacial. This coincides with the well-documented intensification and/or southward shift of the tropical circulation and reflects the strong precipitation-sensitivity of glaciers in arid and semi-arid environments.

  9. Oceanographic gradients and seabird prey community dynamics in glacial fjords

    Science.gov (United States)

    Arimitsu, Mayumi L.; Piatt, John F.; Madison, Erica N.; Conaway, Jeff; Hillgruber, N.

    2012-01-01

    Glacial fjord habitats are undergoing rapid change as a result of contemporary global warming, yet little is known about how glaciers influence marine ecosystems. These ecosystems provide important feeding, breeding and rearing grounds for a wide variety of marine organisms, including seabirds of management concern. To characterize ocean conditions and marine food webs near tidewater glaciers, we conducted monthly surveys of oceanographic variables, plankton, fish and seabirds in Kenai Fjords, Alaska, from June to August of 2007 and 2008. We also measured tidal current velocities near glacial features. We found high sediment load from glacial river runoff played a major role in structuring the fjord marine ecosystem. Submerged moraines (sills) isolated cool, fresh, stratified and silt-laden inner fjord habitats from oceanic influence. Near tidewater glaciers, surface layers of turbid glacial runoff limited availability of light to phytoplankton, but macrozooplankton were abundant in surface waters, perhaps due to the absence of a photic cue for diel migration. Fish and zooplankton community structure varied along an increasing temperature gradient throughout the summer. Acoustic measurements indicated that low density patches of fish and zooplankton were available in the surface waters near glacial river outflows. This is the foraging habitat occupied most by Kittlitz's murrelet (Brachyramphus brevirostris), a rare seabird that appears to be specialized for life in glacially influenced environments. Kittlitz's murrelets were associated with floating glacial ice, and they were more likely to occur near glaciers, in deeper water, and in areas with high acoustic backscatter. Kittlitz's murrelet at-sea distribution was limited to areas influenced by turbid glacial outflows, and where prey was concentrated near the surface in waters with low light penetration. Tidewater glaciers impart unique hydrographic characteristics that influence marine plankton and fish

  10. Early Circum-Arctic Glacial Decay Following the Last Glacial Maximum?

    Science.gov (United States)

    Snow, T.; Alonso-Garcia, M.; Flower, B. P.; Shevenell, A.; Roehl, U.; Goddard, E.

    2012-12-01

    Recent rapid warming, glacial retreat, and sea ice reduction observed in the Arctic suggest extreme regional environmental sensitivity to ongoing anthropogenic climate change. To place these recent environmental changes in context and better understand the forcings and feedbacks involved in Arctic climate change, regional studies of past intervals of rapid warming are required. Paleoceanographic studies from the high-latitude North Atlantic indicate close relationships between meltwater discharges from circum-Arctic ice sheets, perturbations of Atlantic Meridional Overturning Circulation (AMOC), and global climate variations on sub-orbital timescales during the Late Quaternary. During the last glacial-interglacial transition (25-10 ka), when atmospheric temperatures over Greenland warmed 10-15°C and the AMOC experienced millennial-scale variability, low-resolution stable isotope studies from Fram Strait sediment cores indicate that the circum-Arctic ice sheets began to melt earlier than lower latitude Northern Hemisphere ice sheets, discharging their meltwater into the high latitude North Atlantic. Fram Strait, located at the gateway between the Atlantic and Arctic Oceans, is the only region where Arctic meltwater can exchange with the world oceans on both glacial and interglacial timescales. Thus, high-resolution paleoceanographic studies of Fram Strait sediments are critically required for understanding changes in Arctic meltwater flux to the North Atlantic on sub-orbital timescales. Here we present the first high-resolution (Arctic ice sheet decay since the Last Glacial Maximum. Foraminiferal isotopic and elemental, scanning X-Ray Fluorescence, and ice-rafted debris records are used to isolate Arctic meltwater and iceberg discharge signals. Sharp increases in productivity and changes in water mass ventilation are inferred from XRF and foraminiferal geochemical records at ~23 kyr. Planktonic foraminiferal isotope records also suggest early meltwater pulses into

  11. Technical Note: Using wavelet analyses on water depth time series to detect glacial influence in high-mountain hydrosystems

    Directory of Open Access Journals (Sweden)

    S. Cauvy-Fraunié

    2013-04-01

    Full Text Available Worldwide, the rapid shrinking of glaciers in response to ongoing climate change is currently modifying the glacial meltwater contribution to hydrosystems in glacierized catchments. Assessing the contribution of glacier run-off to stream discharge is therefore of critical importance to evaluate potential impact of glacier retreat on water quality and aquatic biota. This task has challenged both glacier hydrologists and ecologists over the last 20 yr due to both structural and functional complexity of the glacier-stream system interface. Here we propose a new methodological approach based on wavelet analyses on water depth time series to determine the glacial influence in glacierized catchments. We performed water depth measurement using water pressure loggers over ten months in 15 stream sites in two glacier-fed catchments in the Ecuadorian Andes (> 4000 m. We determined the global wavelet spectrum of each time series and defined the Wavelet Glacier Signal (WGS as the ratio between the global wavelet power spectrum value at a 24 h-scale and its corresponding significance value. To test the relevance of the WGS we compared it with the percentage of the glacier cover in the catchments, a metric of glacier influence often used in the literature. We then tested whether one month data could be sufficient to reliably determine the glacial influence. As expected we found that the WGS of glacier-fed streams decreased downstream with the increasing of non-glacial tributaries. We also found that the WGS and the percentage of the glacier cover in the catchment were significantly positively correlated and that one month data was sufficient to identify and compare the glacial influence between two sites, provided that the water level time series were acquired over the same period. Furthermore, we found that our method permits to detect glacial signal in supposedly non-glacial sites, thereby evidencing glacial meltwater infiltrations. While we specifically

  12. Glacial geomorphology of the Torres del Paine region (southern Patagonia): Implications for glaciation, deglaciation and paleolake history

    Science.gov (United States)

    García, Juan-Luis; Hall, Brenda L.; Kaplan, Michael R.; Vega, Rodrigo M.; Strelin, Jorge A.

    2014-01-01

    into the Pacific Ocean by the late-glacial period, suggesting that ice southwest of Torres del Paine may have retreated back into the mountains by this time.

  13. Aiding the Interpretation of Ancient Documents

    DEFF Research Database (Denmark)

    Roued-Cunliffe, Henriette

    How can Decision Support System (DSS) software aid the interpretation process involved in the reading of ancient documents? This paper discusses the development of a DSS prototype for the reading of ancient texts. In this context the term ‘ancient documents’ is used to describe mainly Greek...... and Latin texts and the term ‘scholars’ is used to describe readers of these documents (e.g. papyrologists, epigraphers, palaeographers). However, the results from this research can be applicable to many other texts ranging from Nordic runes to 18th Century love letters. In order to develop an appropriate...... tool it is important first to comprehend the interpretation process involved in reading ancient documents. This is not a linear process but rather a recursive process where the scholar moves between different levels of reading, such as ‘understanding the meaning of a character’ or ‘understanding...

  14. AN INTERESTING CASE OF ANCIENT SCHWANNOMA

    Directory of Open Access Journals (Sweden)

    Binu

    2015-01-01

    Full Text Available INTRODUCTION : Schwannoma is a common benign tumour of nerve sheath. Degenerating type of schwannoma is called ancient schwannoma. Ancient schwannomas of scalp are rare and are often misdiagnosed as sebaceous cyst or dermoid cyst. CASE REPORT : We present a thirty two year old male presented with scalp swel ling of eight years duration. X - ray showed no intracranial extension. He underwent excision of the tumour and histopathology was reported as ancient schwannoma. DISCUSSION : Histopathologically , ancient schwannomas charecterised by cellular Antoni type A ar eas and less cellular Antoni type - B areas. 9 th , 7 th , 11 th , 5 th and 4 th cranial nerves are often affected and may be associated with multiple neuro fibramatosis (Von - Recklinghausen’s disease. Impact : Case is presented for its rarity and possible pre - operative misdiagnosis

  15. Ancient Magnetic Reversals: Clues to the Geodynamo.

    Science.gov (United States)

    Hoffman, Kenneth A.

    1988-01-01

    Discusses the question posed by some that the earth's magnetic field may reverse. States that rocks magnetized by ancient fields may offer clues to the underlying reversal mechanism in the earth's core. (TW)

  16. Glacial magnetite dissolution in abyssal NW Pacific sediments - evidence for carbon trapping?

    Science.gov (United States)

    Korff, Lucia; von Dobeneck, Tilo; Frederichs, Thomas; Kasten, Sabine; Kuhn, Gerhard; Gersonde, Rainer; Diekmann, Bernhard

    2016-04-01

    The abyssal North Pacific Ocean's large volume, depth, and terminal position on the deep oceanic conveyor make it a candidate site for deep carbon trapping as postulated by climate theory to explain the massive glacial drawdown of atmospheric CO2. As the major basins of the North Pacific have depths of 5500-6500m, far below the modern and glacial Calcite Compensation Depths (CCD), these abyssal sediments are carbonate-free and therefore not suitable for carbonate-based paleoceanographic proxy reconstructions. Instead, paleo-, rock and environmental magnetic methods are generally well applicable to hololytic abyssal muds and clays. In 2009, the international paleoceanographic research cruise SO 202 INOPEX ('Innovative North Pacific Experiment') of the German RV SONNE collected two ocean-spanning EW sediment core transects of the North Pacific and Bering Sea recovering a total of 50 piston and gravity cores from 45 sites. Out of seven here considered abyssal Northwest Pacific piston cores collected at water depths of 5100 to 5700m with mostly coherent shipboard susceptibility logs, the 20.23m long SO202-39-3, retrieved from 5102 m water depth east of northern Shatsky Rise (38°00.70'N, 164°26.78'E), was rated as the stratigraphically most promising record of the entire core transect and selected for detailed paleo- and environmental magnetic, geochemical and sedimentological investigations. This core was dated by correlating its RPI and Ba/Ti records to well-dated reference records and obviously provides a continuous sequence of the past 940 kyrs. The most striking orck magnetic features are coherent magnetite-depleted zones corresponding to glacial periods. In the interglacial sections, detrital, volcanic and even submicron bacterial magnetite fractions are excellently preserved. These alternating magnetite preservation states seem to reflect dramatic oxygenation changes in the deep North Pacific Ocean and hint at large-scale benthic glacial carbon trapping

  17. The Paleoclimate of the Dead Sea Basin from the Last Glacial Maximum to the Holocene

    Science.gov (United States)

    2001-11-01

    The purpose of this study was to determine the late glacial paleoclimate of the Southern Levant. A study of delta 13C and delta 18O in carbonates...derived from carbon and oxygen isotopes provide insight into the paleoclimate of the Southern Levant. The period from 20-14.6 kya was dry and cool, with...organic matter into the basin. The results of this study agree with other studies based on paleolake levels, pollen levels and paleoclimate studies from the Dead Sea Basin.

  18. 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.

  19. Preformed Nitrate in the Glacial North Atlantic

    Science.gov (United States)

    Homola, K.; Spivack, A. J.; D'Hondt, S.; Estes, E. R.; Insua, T. L.; McKinley, C. C.; Murray, R. W.; Pockalny, R. A.; Robinson, R. S.; Sauvage, J.

    2015-12-01

    Atmospheric CO2 abundances are highly correlated with global temperature variations over the past 800,000 years. Consequently, understanding the feedbacks between climate and CO2 is important for predictions of future climate. Leading hypotheses to explain this feedback invoke changes in ocean biology, circulation, chemistry, and/or gas exchange rates to trap CO2 in the deep ocean, thereby reducing the greenhouse effect of CO2 in the atmosphere. To test these hypotheses, we use sediment pore water profiles of dissolved nitrate and oxygen to reconstruct paleo-preformed nitrate concentrations at two deep-water sites in the western North Atlantic (23°N 57°W, 5557 m water depth; 30°N 58°W, 5367 m water depth). Preformed nitrate increases down-core to 22.7 μM (25.6 m core depth) at the northern site, and to 28.5 μM (27.8 m core depth) at the southern site. The large preformed nitrate gradient between these sites reveals a paleo-boundary between a southern water source high in preformed nitrate and a northern water source with lower concentrations, similar to today's ocean. However, the boundary between these water masses occurs north of where their modern counterparts meet, indicating that Antarctic Bottom Water (AABW) extended farther north during the Last Glacial Maximum (LGM). In addition, the southern source had a higher preformed nitrate concentration than today's AABW (25 μM), contradicting hypotheses that nutrient utilization was more efficient in the Southern Ocean deep-water formation regions during the LGM. Comparison to our previous Pacific data reveals that the average preformed nitrate concentration of the deep ocean was slightly higher during the LGM than today. This result implies that the CO2-climate feedback was not principally due to more efficient nitrate utilization.

  20. A high-resolution climatic change since the Late Glacial Age inferred from multi-proxy of sediments in Qinghai Lake

    Institute of Scientific and Technical Information of China (English)

    SHEN Ji; LIU Xingqi; Ryo Matsumoto; WANG Sumin; YANG Xiangdong

    2005-01-01

    Based on multi-proxy analysis of pollen, carbonate, TOC, TN and δ13C of organic matters, a high-resolution climatic evolution of Qinghai Lake since the Late Glacial Age is reconstructed. The results indicate that the boundary between the Last Glacial Maximum and the Late Glacial Age is at about 18.2 cal.ka BP. The warm and wet period, which began at about 15.4 cal.ka BP, culminated at 7.4 cal.ka BP and came to its end at about 4.5 cal.ka BP. After that, the climate gradually became cold and dry. The multi-proxy analysis indicates that the climate fluctuated greatly during the transitional period from the Late glacial Age to the Holocene, and this is in good accordance with that reflected by deep sea cores of North Atlantic, ice cores of Greenland, lake sediments in Europe, loess sequences and Guliya ice core in China. The climatic evolutional characteristic of the Qinghai Lake since the Late Glacial Age shows that the driving force of the East-Asia Monsoon correlates with solar radiation on the ten-thousand-year scale.

  1. Mummies and dental health in the ancient Ilo valley, southern Peru

    Directory of Open Access Journals (Sweden)

    Simon Hillson

    2003-10-01

    Full Text Available In the very arid climate of southern Peru, archaeological remains, including many human burials, are extremely well preserved. Study of the teeth of mummified people from different cultural groups and time periods is beginning to provide evidence of diet and disease among the ancient inhabitants of the Ilo valley between the foot-hills of the Andes and the desert coast.

  2. Mysteries of Antiquity: Lessons To Engage Middle School Students in Ancient/Medieval History.

    Science.gov (United States)

    Fischer, Max W.

    This instructional packet is intended to help classroom instructors introduce fascinating quandaries rarely featured in history textbooks about the ancient and medieval eras. Most of the 13 lesson plans require only 1 or 2 class periods to complete, permitting the teacher to enhance the presentation of a particular unit without fear of devoting…

  3. Sub-glacial Origin of the Hot Springs Bay Valley hydrothermal System, Akutan, Alaska

    Science.gov (United States)

    Stelling, P. L.; Tobin, B.; Knapp, P.

    2015-12-01

    Exploration for geothermal energy in Hot Springs Bay Valley (HSBV) on Akutan Island, Alaska, has revealed a rich hydrothermal history, including what appears to be a stage of peak activity during a significant glacial period. Alteration mineralogy observed in 754 m of drill core recovered from the outflow zone is dominated by chlorite and includes minor smectite clays, a suite of zeolite species and several moderately high-temperature hydrothermal minerals (epidote/clinozoisite, prehnite, adularia and wairakite). The latter minerals each have minimum formation temperatures exceeding 200 oC, and fluid inclusion results in related calcite crystals indicate temperatures of formation to be as high as 275 oC, some 100 oC hotter than the modern boiling point with depth (BPD) curve at that depth (>62 m). In order to maintain liquid temperatures this high, the pressure during mineralization must have been substantially greater (~680 bar), a pressure change equivalent to erosion of ~280 m of rock (ρ=2.5 g/cm3). Although glacial erosion rates are too low (0.034 mm/yr; Bekele et al., 2003) for this amount of erosion to occur in a single glaciation, glacial melting and ablation are substantially more rapid (~100 mm/yr; Bekele et al., 2003; Person et al., 2012). Thus, a more probable scenario than pure erosion is that peak hydrothermal conditions occurred during a large glacial event, with the added pressure from the overlying ice allowing the high temperature minerals to form closer to the ground surface. Subsequent melting of the ice eroded upper tributary valleys and upper levels of the originally smectite-rich alteration assemblage, explaining the paucity of swelling clays in the region. We present mineralogical, fluid inclusion and geochronologic evidence to support these conclusions, and discuss the general implications of sub-glacial hydrothermal system formation and geothermal resource potential. References: Bekele, E., Rostron, B. and Person, M. (2003) Fluid pressure

  4. The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

    Science.gov (United States)

    Buchanan, Pearse J.; Matear, Richard J.; Lenton, Andrew; Phipps, Steven J.; Chase, Zanna; Etheridge, David M.

    2016-12-01

    The ocean's ability to store large quantities of carbon, combined with the millennial longevity over which this reservoir is overturned, has implicated the ocean as a key driver of glacial-interglacial climates. However, the combination of processes that cause an accumulation of carbon within the ocean during glacial periods is still under debate. Here we present simulations of the Last Glacial Maximum (LGM) using the CSIRO Mk3L-COAL (Carbon-Ocean-Atmosphere-Land) earth system model to test the contribution of physical and biogeochemical processes to ocean carbon storage. For the LGM simulation, we find a significant global cooling of the surface ocean (3.2 °C) and the expansion of both minimum and maximum sea ice cover broadly consistent with proxy reconstructions. The glacial ocean stores an additional 267 Pg C in the deep ocean relative to the pre-industrial (PI) simulation due to stronger Antarctic Bottom Water formation. However, 889 Pg C is lost from the upper ocean via equilibration with a lower atmospheric CO2 concentration and a global decrease in export production, causing a net loss of carbon relative to the PI ocean. The LGM deep ocean also experiences an oxygenation ( > 100 mmol O2 m-3) and deepening of the calcite saturation horizon (exceeds the ocean bottom) at odds with proxy reconstructions. With modifications to key biogeochemical processes, which include an increased export of organic matter due to a simulated release from iron limitation, a deepening of remineralisation and decreased inorganic carbon export driven by cooler temperatures, we find that the carbon content of the glacial ocean can be sufficiently increased (317 Pg C) to explain the reduction in atmospheric and terrestrial carbon at the LGM (194 ± 2 and 330 ± 400 Pg C, respectively). Assuming an LGM-PI difference of 95 ppm pCO2, we find that 55 ppm can be attributed to the biological pump, 28 ppm to circulation changes and the remaining 12 ppm to solubility. The biogeochemical

  5. Late Glacial climate and palaeoenvironment in the Southern Carpathian Mountains inferred by chironomid and pollen analyses

    Science.gov (United States)

    Tóth, M.; Heiri, O.; Magyari, E.; Braun, M.; Buczkó, K.; Bálint, M.; Jakab, G.

    2009-04-01

    The Southern Carpathian Mountains have several glacial lakes with their sediments extending back to the Late Glacial period (ca. 11,500-14,700 calibrated radiocarbon years BP). This area has so far missed quantitative palaeoclimate records that are however much needed in order to obtain a continental-scale picture of ecosystem reorganization in response to rapid climatic changes during the Late Glacial. High-resolution chironomid and pollen analyses can both provide such records. In this study these two methods are applied to the sediment sequence of a small sub-alpine lake, Taul dintre Brazi (Retezat Mts, 1740 m a.s.l., 0.5 ha). The lake is situated on base-poor, granite bedrock, within the Picea abies forest belt. Our aim was (1) to study changes in the chironomid fauna, (2) to obtain summer temperature estimates using a chironomid-mean July air temperature inference model, and finally (3) to compare the chironomid-inferred climate record with a pollen-based quantitative climate record (plant functional type method). Here we provide first results from this multi-proxy study. The Late Glacial and Early Holocene part of this core was analysed at 100-200 yr resolution. During the Oldest Dryas the chironomid fauna was dominated by Pseudodiamesa and Tanytarsini species; the start of the Lateglacial interstadial was marked by the diversification of Tanytarsini (Tanytarsus lugens-type, Tanytarsus pallidicornis-type, Paratanytarsus sp, Micropsectra insignilobus-type) and the disappearance of Pseudodiamesa suggesting a distinct increase in summer temperature. At the same time afforestation by Larix, Pinus cembra, Pinus mugo and Picea abies was signaled by the pollen, stomatal and plant macrofossil records. During the Younger Dryas reversal the chironomid fauna showed increasing abundance of Micropsectra insignilobus-type, a chironomid typical for cool, nutrient poor lakes whereas the pollen, plant macrofossil and stomatal records pointed to a decrease of Picea abies

  6. Glacial erosion of high-elevation low-relief summits on passive continental margins constrained by cosmogenic nuclides

    DEFF Research Database (Denmark)

    Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou;

    , indicating that warm-based ice eroded the summits during the last glacial period. From the isotope concentrations we model denudation histories using a recently developed Monte Carlo Markov Chain inversion model (Knudsen et al, 2015). The model relies on the benthic d18O curve (Lisiecki and Raymo, 2005......., and Raymo, M. E. "A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records." Paleoceanography 20.1 (2005)....

  7. 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

  8. From the Last Interglacial to the Anthropocene: Modelling a Complete Glacial Cycle (PalMod)

    Science.gov (United States)

    Brücher, Tim; Latif, Mojib; Claussen, Martin; Schulz, Michael

    2016-04-01

    We will give a short overview of the national climate modelling initiative (PalMod - Paleo Modelling, www.palmod.de) on the understanding of the climate system dynamics and its variability during the last glacial cycle. PalMod is funded by the German Federal Ministry of Education and Research (BMBF) and its specific topics are: (i) to identify and quantify the relative contributions of the fundamental processes which determined the Earth's climate trajectory and variability during the last glacial cycle, (ii) to simulate with comprehensive Earth System Models (ESMs) the climate from the peak of the last interglacial - the Eemian warm period - up to the present, including the changes in the spectrum of variability, and (iii) to assess possible future climate trajectories beyond this century during the next millennia with sophisticated ESMs tested in such a way. The research is intended to be conducted over a period of 10 years, but with shorter funding cycles. The envisioned approach is innovative in three respects. First, the consortium aims at simulating a full glacial cycle in transient mode and with comprehensive ESMs which allow full interactions between the physical and biogeochemical components of the Earth system, including ice sheets. Second, we shall address climate variability during the last glacial cycle on a large range of time scales, from interannual to multi-millennial, and attempt to quantify the relative contributions of external forcing and processes internal to the Earth system to climate variability at different time scales. Third, in order to achieve a higher level of understanding of natural climate variability at time scales of millennia, its governing processes and implications for the future climate, we bring together three different research communities: the Earth system modeling community, the proxy data community and the computational science community. The consortium consists of 18 partners including all major modelling centers within

  9. Weak oceanic heat transport as a cause of the instability of glacial climates

    Energy Technology Data Exchange (ETDEWEB)

    Colin de Verdiere, Alain [Universite de Bretagne Occidentale, Laboratoire de Physique des Oceans, Alain Colin de Verdiere, Brest 3 (France); Te Raa, L. [Utrecht University, Institute for Marine and Atmospheric Research Utrecht, Utrecht (Netherlands); Netherlands Organisation for Applied Scientific Research TNO, The Hague (Netherlands)

    2010-12-15

    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 large insulation of the ocean by the extensive sea ice cover changes the temperature boundary condition and the deepwater formation regions moves much further South. The nature of the instability is of oceanic origin, identical to that found in ocean models under mixed boundary conditions. With similar strengths of the oceanic circulation and rates of deep water formation for warm and cold climates, the loss of stability of the cold climate is due to the weak thermal stratification caused by the cooling of surface waters, the deep water temperatures being regulated by the temperature of freezing. Weaker stratification with similar overturning leads to a weakening of the meridional oceanic heat transport which is the major negative feedback stabilizing the oceanic circulation. Within the unstable regime periodic millennial oscillations occur spontaneously. The climate oscillates between a strong convective thermally driven oceanic state and a weak one driven by large salinity gradients. Both states are unstable. The atmosphere of low thermal inertia is carried along by the oceanic overturning while the variation of sea ice is out of phase with the oceanic heat content. During the abrupt warming events that punctuate the course of a millennial oscillation, sea ice variations are shown respectively to damp (amplify) the amplitude of the oceanic (atmospheric) response. This sensitivity of the oceanic circulation to a reduced concentration of greenhouse gases and to freshwater forcing adds support to the hypothesis that the millennial oscillations of the last glacial period, the so called Dansgaard - Oeschger events, may be internal instabilities of the climate system

  10. Obliquity pacing of the late Pleistocene glacial terminations.

    Science.gov (United States)

    Huybers, Peter; Wunsch, Carl

    2005-03-24

    The 100,000-year timescale in the glacial/interglacial cycles of the late Pleistocene epoch (the past approximately 700,000 years) is commonly attributed to control by variations in the Earth's orbit. This hypothesis has inspired models that depend on the Earth's obliquity (approximately 40,000 yr; approximately 40 kyr), orbital eccentricity (approximately 100 kyr) and precessional (approximately 20 kyr) fluctuations, with the emphasis usually on eccentricity and precessional forcing. According to a contrasting hypothesis, the glacial cycles arise primarily because of random internal climate variability. Taking these two perspectives together, there are currently more than thirty different models of the seven late-Pleistocene glacial cycles. Here we present a statistical test of the orbital forcing hypothesis, focusing on the rapid deglaciation events known as terminations. According to our analysis, the null hypothesis that glacial terminations are independent of obliquity can be rejected at the 5% significance level, whereas the corresponding null hypotheses for eccentricity and precession cannot be rejected. The simplest inference consistent with the test results is that the ice sheets terminated every second or third obliquity cycle at times of high obliquity, similar to the original proposal by Milankovitch. We also present simple stochastic and deterministic models that describe the timing of the late-Pleistocene glacial terminations purely in terms of obliquity forcing.

  11. Magnetic Strips Preserve Record of Ancient Mars

    Science.gov (United States)

    1999-01-01

    have the resolution to detect these features,' Acuna noted. 'We began with misfortune, and ended up winning the lottery.' The bands of magnetized crust apparently formed in the distant past when Mars had an active dynamo, or hot core of molten metal, which generated a global magnetic field. Mars was geologically active, with molten rock rising from below cooling at the surface and forming new crust. As the new crust solidified, the magnetic field that permeated the rock was 'frozen' in the crust. Periodically, conditions in the dynamo changed and the global magnetic field reversed direction. The oppositely directed magnetic field was then frozen into newer crust. [figure removed for brevity, see original site] (P50331,MRPS94770) Above: These images are an artist's concept of the process that may have generated magnetic stripes in the crust of ancient Mars. In the left image, the blue arrows and compass needle indicate the direction of the magnetic field. The yellow-orange shape represents a pool of molten rock (magma)upwelling beneath the Martian crust. The red and blue bands are magnetized crust on either side of a spreading center, or rift. 'Like a Martian tape recorder, the crust has preserved a fossil record of the magnetic field directions that prevailed at different times in the ancient past,' Connerney said. When the planet's hot core cooled, the dynamo ceased and the global magnetic field of Mars vanished. However, a record of the magnetic field was preserved in the crust and detected by the Global Surveyor instrument. The mission's map of Martian magnetic regions may help solve another mystery -- the origin of a striking difference in appearance between the smooth, sparsely cratered northern lowlands of Mars and the heavily cratered southern highlands. The map reveals that the northern regions are largely free of magnetism, indicating the northern crust formed after the dynamo died. 'The dynamo likely died a few hundred million years after Mars' formation. One

  12. Chronology of glaciations in the Cantabrian Mountains (NW Iberia) during the Last Glacial Cycle based on in situ-produced 10Be

    Science.gov (United States)

    Rodríguez-Rodríguez, Laura; Jiménez-Sánchez, Montserrat; Domínguez-Cuesta, María José; Rinterknecht, Vincent; Pallàs, Raimon; Bourlès, Didier

    2016-04-01

    The mountain ranges of the Iberian Peninsula preserve a valuable record of past glaciations that may help reconstruct past atmospheric circulation patterns in response to cooling events in the North Atlantic Ocean. Available chronologies for the glacial record of the Cantabrian Mountains, which are mainly based on radiocarbon and luminescence dating of glacial-related sediments, suggest that glaciers recorded their Glacial Maximum (GM) during MIS 3 and experienced a later Last Glacial Maximum (LGM) advance. This LGM extent is not established yet, preventing a fair correlation with available Cosmic Ray Exposure (CRE) based chronologies for the glacial record of the Pyrenees and the Sistema Central. We present a glacial reconstruction and a 10Be CRE chronology for the Porma valley, in the southern slope of the central Cantabrian Mountains. Glacial evidence at the lowest altitudes correspond to erratic boulders and composite moraines whose minimum 10Be CRE age of 113.9 ± 7.1 ka suggests that glaciers were at their maximum extent during MIS 5d, most likely in response to the minima in summertime insolation of the Last Glacial Cycle. Recessional moraines preserved within the glacial maximum limits allow the assessment of subsequent glacier advances or stagnations. The most remarkable advance took place prior to 55.7 ± 4.0 ka (probably at the end of MIS 4), consistently with minimum radiocarbon ages previously reported for lacustrine glacial-related deposits in the Cantabrian Mountains. A limited number of 10Be CRE ages from a composite moraine suggest a possible advance of the Porma glacier coeval with the global LGM; the glacier front attributed to the LGM would be placed within the margins of the previous GM like in the western Pyrenees. Erratic boulders perched on an ice-moulded bedrock surface provided a mean 10Be CRE age of 17.7 ± 1.0 ka, suggesting that part of the recessional moraine sequence corresponds to minor advances or stagnations of the glacier fronts

  13. Crevassing and calving of glacial ice

    Science.gov (United States)

    Kenneally, James Patrick

    Calving of ice is a relatively new area of research in the still young field of glaciology. In the short time that calving has been studied, it has been mainly treated as an afterthought, with the predominant mode of thinking being that it will happen so to concern oneself with why is not important. Many studies dealt with observations of calving front positions over time vs. ice velocity in an attempt to quantify the calving rate as the difference between the two, while others have attempted to deduce some empirical relationship between calving rate and variables such as water depth or temperature. This study instead addresses the question of why, where, and when ice will first become crevassed, which is an obviously necessary condition for a later calving event to occur. Previous work examining the causes of calving used ideas put forth from a variety of fields, including civil engineering, materials science, and results from basic physics and mechanics. These theories are re-examined here and presented as part of a larger whole. Important results from the field of fracture mechanics are utilized frequently, and these results can be used as a predictor of ice behavior and intrinsic properties of ice, as well as properties like back stresses induced by local pinning points and resistive shears along glacial ice boundaries. A theory of fracture for a material experiencing creep is also presented with applications to ice shelves and crevasse penetration. Finally, a speculative theory regarding large scale iceberg formation is presented. It is meant mainly as an impetus to further discussion on the topic, with the hope that a model relating crevasse geometries to flow parameters can result in crevasse spacings that could produce the tabular icebergs which are so newsworthy. The primary focus of this thesis is to move away from the "after the fact" studies that are so common in calving research, and instead devote energy to determining what creates the conditions that

  14. Genetic diversity among ancient Nordic populations.

    Science.gov (United States)

    Melchior, Linea; Lynnerup, Niels; Siegismund, Hans R; Kivisild, Toomas; Dissing, Jørgen

    2010-01-01

    Using established criteria for work with fossil DNA we have analysed mitochondrial DNA from 92 individuals from 18 locations in Denmark ranging in time from the Mesolithic to the Medieval Age. Unequivocal assignment of mtDNA haplotypes was possible for 56 of the ancient individuals; however, the success rate varied substantially between sites; the highest rates were obtained with untouched, freshly excavated material, whereas heavy handling, archeological preservation and storage for many years influenced the ability to obtain authentic endogenic DNA. While the nucleotide diversity at two locations was similar to that among extant Danes, the diversity at four sites was considerably higher. This supports previous observations for ancient Britons. The overall occurrence of haplogroups did not deviate from extant Scandinavians, however, haplogroup I was significantly more frequent among the ancient Danes (average 13%) than among extant Danes and Scandinavians (approximately 2.5%) as well as among other ancient population samples reported. Haplogroup I could therefore have been an ancient Southern Scandinavian type "diluted" by later immigration events. Interestingly, the two Neolithic samples (4,200 YBP, Bell Beaker culture) that were typed were haplogroup U4 and U5a, respectively, and the single Bronze Age sample (3,300-3,500 YBP) was haplogroup U4. These two haplogroups have been associated with the Mesolithic populations of Central and Northern Europe. Therefore, at least for Southern Scandinavia, our findings do not support a possible replacement of a haplogroup U dominated hunter-gatherer population by a more haplogroup diverse Neolithic Culture.

  15. Coastal response to simultaneous mid-Holocene climate and sea-level changes: Lessons from ancient Egypt

    Science.gov (United States)

    Hein, C. J.; FitzGerald, D. M.; Milne, G. A.; Bard, K. A.; Fattovich, R.

    2011-12-01

    Coastal evolution during the Holocene has been driven by complex interactions between changes in sea level, climate, and sedimentation processes. Along the Egyptian Red Sea coast, a post-glacial marine transgression drowned a series of wadi channels, flooding their lower reaches to create shallow lagoons. Archeological investigations at one such site, Mersa / Wadi Gawasis, have uncovered the existence of an ancient Egyptian harbor along a carbonate / conglomerate terrace located 600 m landward of the modern shoreline; this discovery documented the world's earliest (3.5 - 4.0 ka) archaeological evidence of long-distance seafaring. This site is interpreted to have been a harbor servicing trade routes along the African Red Sea coast. Sedimentological, malacological, chorological, and foraminiferal analyses indicate that this harbor was located within a low energy, 6 - 8 m deep, tidal embayment that once extended ~1 km inland of the modern shore. A buried coral-beach rock platform and tidal flat sediments are found ubiquitously along the periphery of the paleo-bay and at elevations of up to 1 m above modern mean sea level. Wave-cut notches and erosional terraces observed at 1.1 - 1.8 m above modern sea level along the modern shoreline provide additional evidence of a higher-than-present stand of sea-level during the mid-Holocene. Sea-level predictions generated using a site-specific isostatic model for the northern the Red Sea confirm the presence of 0.5 - 2 m highstand at 5 ka. Reconstructions indicate that the bay at Mersa / Wadi Gawasis reached its maximum surface area prior to the highstand. Preliminary closure was driven by sediment inputs from the adjacent wadi, enhanced by the wetter climate of the African Humid Period, combined with a slowing rate of sea-level rise, thus demonstrating the dominance of sedimentary processes during this period. Following the highstand, slowly falling sea level coincidental with climatic aridization allowed for the establishment

  16. Synchrotron radiation analysis on ancient Egyptian vitreous materials

    Energy Technology Data Exchange (ETDEWEB)

    Yamahana, Kyoko [Tokai Univ., Hiratsuka, Kanagawa (Japan). Lecture of Egyptian Archaeology

    2000-07-01

    Ancient Egyptian vitreous materials, namely faience and glass, share the same elemental composition. But they appear to have originated separately. Faience objects appear as early as the Predynastic period, and glass was introduced from Mesopotamia during the New Kingdom. These faience and glass objects were not of daily use, rather they were regarded as religious symbols or luxury status goods. Most of the products were coloured blue, but we see an increased use of other colours during the New Kingdom (c.1550-1069BC). This tendency corresponds to the period of both territorial and political expansion of Egypt. A non-destructive SR-XRF experiment at SPring-8 was conducted last winter, aiming to determine the regional trait of elemental composition by examining the pattern and ratio of rare earth elements. As a result, we could observe some distinctive rare earth elements that may indicate regional variation. (author)

  17. Ancient Egyptian chronology and the astronomical orientation of pyramids

    Science.gov (United States)

    Spence, Kate

    2000-11-01

    The ancient Egyptian pyramids at Giza have never been accurately dated, although we know that they were built approximately around the middle of the third millennium BC. The chronologies of this period have been reconstructed from surviving lists of kings and the lengths of their reigns, but the lists are rare, seldom complete and contain known inconsistencies and errors. As a result, the existing chronologies for that period (the Old Kingdom) can be considered accurate only to about +/-100 years, a figure that radiocarbon dating cannot at present improve. Here I use trends in the orientation of Old Kingdom pyramids to demonstrate that the Egyptians aligned them to north by using the simultaneous transit of two circumpolar stars. Modelling the precession of these stars yields a date for the start of construction of the Great Pyramid that is accurate to +/-5 yr, thereby providing an anchor for the Old Kingdom chronologies.

  18. Interpretation and preliminary simulation of the 40 ka periodicity of the Quaternary glaciation

    Institute of Scientific and Technical Information of China (English)

    LI Nan; CHEN Xing

    2007-01-01

    More and more proxy records approved that the periodicity of the glacial cycles is about 40 ka before MPT (middle Pleistocene transition) as early as late Tertiary from 3.0 Ma to 0.9 Ma, whereas it changes to about 100 ka after MPT.Summer insolation at high latitude in Northern Hemisphere, usually considered as the main external force for the ice age, is dominated by the 23 ka precession period, which does not match the period of the glacial cycles.In this paper, we define an energy index C and its threshold Ct that indicate the net energy supply and the overall response of the climate system.The difference between these two parameters determines whether the ice sheet melts or not, and accordingly the start and termination of the interglacial stages, as well as the periodicity of glacial oscillations.Based on the energy threshold hypothesis, the preliminary simulation experiments are made to test the period of the glacial cycles and driven factors from a conceptual model.The results indicate that energy index C and threshold Ct can interpret not only the 40 ka periodicity before MPT, but also the quasi-100 ka periodicity after MPT to some extent, and the 40 ka is the basic period of the glacial cycles, which discloses the inherent continuity of climatic change before and after MPT.

  19. Use of x-ray fluorescence and diffraction techniques in studying ancient ceramics of Sri Lanka

    Science.gov (United States)

    Karunaratne, B. S. B.

    2012-07-01

    Ceramics were produced for centuries in Sri Lanka for various purposes. Ancient ceramic articles such as pottery, bricks, tiles, sewer pipes, etc, were made from naturally occurring raw materials. Use of X-ray fluorescence (XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) in characterizing of two ancient ceramic samples from two different archaeological sites in Sri Lanka is presented. The information obtained in this manner is used to figure out the ancient ceramic technology, particularly to learn about the raw materials used, the source of raw materials, processing parameters such as firing temperature or binders used in ceramic production. This information then can be used to explore the archaeometric background such as the nature and extent of cultural and technological interaction between different periods of history in Sri Lanka.

  20. Extensive wet episodes in Late Glacial Australia resulting from high-latitude forcings

    Science.gov (United States)

    Bayon, Germain; De Deckker, Patrick; Magee, John W.; Germain, Yoan; Bermell, Sylvain; Tachikawa, Kazuyo; Norman, Marc D.

    2017-01-01

    Millennial-scale cooling events termed Heinrich Stadials punctuated Northern Hemisphere climate during the last glacial period. Latitudinal shifts of the intertropical convergence zone (ITCZ) are thought to have rapidly propagated these abrupt climatic signals southward, influencing the evolution of Southern Hemisphere climates and contributing to major reorganisation of the global ocean-atmosphere system. Here, we use neodymium isotopes from a marine sediment core to reconstruct the hydroclimatic evolution of subtropical Australia between 90 to 20 thousand years ago. We find a strong correlation between our sediment provenance proxy data and records for western Pacific tropical precipitations and Australian palaeolakes, which indicates that Northern Hemisphere cooling phases were accompanied by pronounced excursions of the ITCZ and associated rainfall as far south as about 32°S. Comparatively, however, each of these humid periods lasted substantially longer than the mean duration of Heinrich Stadials, overlapping with subsequent warming phases of the southern high-latitudes recorded in Antarctic ice cores. In addition to ITCZ-driven hydroclimate forcing, we infer that changes in Southern Ocean climate also played an important role in regulating late glacial atmospheric patterns of the Southern Hemisphere subtropical regions.

  1. Sea level and ground water table depth (WTD): A biogeochemical pacemaker for glacial-interglacial cycling

    Science.gov (United States)

    Cowling, S. A.

    2016-11-01

    The role that changes in sea level have on potential carbon-climate feedbacks are discussed as a potential contributing mechanism for terminating glacial periods. Focus will be on coastal wetlands because these systems can be substantially altered by changing sea level and ground water table depth (WTD); in addition to being important moderators of the exchange of nutrients and energy between terrestrial and marine ecosystems. A hypothesis is outlined that describes how the release of carbon from formerly anaerobic wetland soils and sediments can influence climate when sea levels begin to decline. As ground WTD deepens and eventually recedes from the surface, coastal wetland basins may become isolated from their belowground source of water. With their primary source of base flow removed, coastal wetlands likely dried up, promoting decomposition of the carbon compounds buried in their sediments. Depending on the timing of basin isolation and the timing of decomposition, glacial sea level lows could have triggered a relatively large positive carbon feedback on climate warming, just at the time when a new interglacial period is about to begin.

  2. Effects of additive noise on the stability of glacial cycles

    CERN Document Server

    Mitsui, Takahito

    2016-01-01

    It is well acknowledged that the sequence of glacial-interglacial cycles is paced by the astronomical forcing. However, how much is the sequence robust against natural fluctuations associated, for example, with the chaotic motions of atmosphere and oceans? In this article, the stability of the glacial-interglacial cycles is investigated on the basis of simple conceptual models. Specifically, we study the influence of additive white Gaussian noise on the sequence of the glacial cycles generated by stochastic versions of several low-order dynamical system models proposed in the literature. In the original deterministic case, the models exhibit different types of attractors: a quasiperiodic attractor, a piecewise continuous attractor, strange nonchaotic attractors, and a chaotic attractor. We show that the combination of the quasiperiodic astronomical forcing and additive fluctuations induce a form of temporarily quantised instability. More precisely, climate trajectories corresponding to different noise realiza...

  3. Twins in Ancient Greece: a synopsis.

    Science.gov (United States)

    Malamitsi-Puchner, Ariadne

    2016-01-01

    This brief outline associates twins with several aspects of life in Ancient Greece. In Greek mythology twins caused ambivalent reactions and were believed to have ambivalent feelings for each other. Very often, they were viewed as the representatives of the dualistic nature of the universe. Heteropaternal superfecundation, which dominates in ancient myths, explains on one hand, the god-like qualities and, on the other hand, the mortal nature of many twins. An assumption is presented that legends referring to twins might reflect the territorial expansions of Ancient Greeks in Northern Mediterranean, around the Black Sea, in Asia Minor, as well as North East Africa. In conclusion, in Greek antiquity, twins have been used as transitional figures between myth and reality.

  4. Genetic diversity among ancient Nordic populations

    DEFF Research Database (Denmark)

    Melchior, Linea Cecilie; Lynnerup, Niels; Siegismund, Hans Redlef

    2010-01-01

    the ancient Danes (average 13%) than among extant Danes and Scandinavians ( approximately 2.5%) as well as among other ancient population samples reported. Haplogroup I could therefore have been an ancient Southern Scandinavian type "diluted" by later immigration events. Interestingly, the two Neolithic...... samples (4,200 YBP, Bell Beaker culture) that were typed were haplogroup U4 and U5a, respectively, and the single Bronze Age sample (3,300-3,500 YBP) was haplogroup U4. These two haplogroups have been associated with the Mesolithic populations of Central and Northern Europe. Therefore, at least...... for Southern Scandinavia, our findings do not support a possible replacement of a haplogroup U dominated hunter-gatherer population by a more haplogroup diverse Neolithic Culture....

  5. The Vindolanda Tablets and the Ancient Economy

    DEFF Research Database (Denmark)

    Evers, Kasper Grønlund

    , a model is outlined which takes into account the different economic behaviours revealed by the tablets and attempts to fit them together into one coherent, economic system, whilst also relating the activities to questions of scale in the ancient economy; moreover, the conclusions drawn in the study......, the aim is to investigate how best to comprehend the economic system attested at Vindolanda and to consider the wider implications for studies of the ancient economy in general. This is accomplished by a three-step approach: first, the nature of the Vindolandan evidence is assessed, and the state...... of research on both studies of the ancient economy and the economy of early Roman Britain is accounted for, so as to highlight the value of the Vindolanda Tablets and lay the ground for the interpretations which follow. Secondly, the economic activities attested by the tablets are analysed in terms of market...

  6. Palaeoparasitology - Human Parasites in Ancient Material.

    Science.gov (United States)

    Araújo, Adauto; Reinhard, Karl; Ferreira, Luiz Fernando

    2015-01-01

    Parasite finds in ancient material launched a new field of science: palaeoparasitology. Ever since the pioneering studies, parasites were identified in archaeological and palaeontological remains, some preserved for millions of years by fossilization. However, the palaeoparasitological record consists mainly of parasites found specifically in human archaeological material, preserved in ancient occupation sites, from prehistory until closer to 2015. The results include some helminth intestinal parasites still commonly found in 2015, such as Ascaris lumbricoides, Trichuris trichiura and hookworms, besides others such as Amoebidae and Giardia intestinalis, as well as viruses, bacteria, fungi and arthropods. These parasites as a whole provide important data on health, diet, climate and living conditions among ancient populations. This chapter describes the principal findings and their importance for knowledge on the origin and dispersal of infectious diseases.

  7. The biochemistry of ancient DNA in bone.

    Science.gov (United States)

    Tuross, N

    1994-06-15

    The amount of DNA in ancient bone was determined by ethidium bromide staining after the removal of the potent Taq inhibitor, fulvic acid. A complete decalcification and a perfusion protocol were used to recover DNA from bone. A variety of purification techniques including molecular sieve, hydroxyapatite binding and 'Magic' preparations yielded DNA that spanned from 3.4 micrograms/g of bone to below detectable limits. Fulvic acid was shown to interfere with the quantification of DNA derived from ancient human skeletal material one hundred to over seven thousand years old. Scanning UV in the 300 to 230 nm range is a simple and sensitive technique for documenting fulvic acid contamination in ancient bone extracts.

  8. The importance of studying inherited hematological disorders in ancient Anatolian populations

    Directory of Open Access Journals (Sweden)

    Yeşim Doğan Alakoç

    2011-12-01

    Full Text Available Before analysis of DNA from ancient remains was possible, anthropologists studied evolution and migration patterns using data obtained from population genetic studies on modern populations combined with data obtained from morphological evaluations of ancient remains. Currently, DNA analysis of ancient populations is making a valuable contribution to these efforts. Researchers that perform ancient DNA analysis prefer to study polymorphisms on the Y chromosome or mitochondrial DNA because the results are easier to statistically evaluate. To evaluate polymorphisms on diploid genomes, which are more informative, only mutations that have been extensively examined in modern populations should be chosen. The most extensively evaluated mutations are those related to prevalent inherited disorders. As such, beta-thalassemia, sickle cell anemia, FVL mutation of globin and the factor V genes are good candidates for DNA studies in ancient populations. These mutations are common in Anatolia, host to many civilizations since the Paleolithic period. This history makes Anatolia a good place for conducting research that could enhance our understanding of human evolution and migration patterns.

  9. Three Thousand Years of Continuity in the Maternal Lineages of Ancient Sheep (Ovis aries) in Estonia.

    Science.gov (United States)

    Rannamäe, Eve; Lõugas, Lembi; Speller, Camilla F; Valk, Heiki; Maldre, Liina; Wilczyński, Jarosław; Mikhailov, Aleksandr; Saarma, Urmas

    2016-01-01

    Although sheep (Ovis aries) have been one of the most exploited domestic animals in Estonia since the Late Bronze Age, relatively little is known about their genetic history. Here, we explore temporal changes in Estonian sheep populations and their mitochondrial genetic diversity over the last 3000 years. We target a 558 base pair fragment of the mitochondrial hypervariable region in 115 ancient sheep from 71 sites in Estonia (c. 1200 BC-AD 1900s), 19 ancient samples from Latvia, Russia, Poland and Greece (6800 BC-AD 1700), as well as 44 samples of modern Kihnu native sheep breed. Our analyses revealed: (1) 49 mitochondrial haplotypes, associated with sheep haplogroups A and B; (2) high haplotype diversity in Estonian ancient sheep; (3) continuity in mtDNA haplotypes through time; (4) possible population expansion during the first centuries of the Middle Ages (associated with the establishment of the new power regime related to 13th century crusades); (5) significant difference in genetic diversity between ancient populations and modern native sheep, in agreement with the beginning of large-scale breeding in the 19th century and population decline in local sheep. Overall, our results suggest that in spite of the observed fluctuations in ancient sheep populations, and changes in the natural and historical conditions, the utilisation of local sheep has been constant in the territory of Estonia, displaying matrilineal continuity from the Middle Bronze Age through the Modern Period, and into modern native sheep.

  10. Geometric dependency of Tibetan lakes on glacial runoff

    Directory of Open Access Journals (Sweden)

    V. H. Phan

    2013-10-01

    Full Text Available 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, accurate quantification of glacial changes is difficult over the high-relief Tibetan Plateau. However, it has recently been shown that it is possible to directly assess water level changes of a significant number of the ~900 Tibetan lakes with an area over 1 km2. This paper exploits different remote sensing products to create drainage links between Tibetan glaciers, lakes and rivers. The results allow us to differentiate between lakes with and without outlet. In addition, we introduce the notion of geometric dependency of a lake on glacial runoff, defined as the ratio between the total area of glaciers draining into a lake and the total area of the lake catchment. We determined these dependencies for all ~900 sufficiently large Tibetan lakes. To do so, we combined three remote sensing products: the CAREERI glacier mask product, a lake mask product based on the MODIS MOD44W water product and the HydroSHEDS river network product derived from Shuttle Radar Topography Mission (SRTM elevation data. Using a drainage network analysis, we determined all drainage links between glaciers and lakes. The results show that 25.3% of the total glacier area directly drains into one of 244 Tibetan lakes. The results also give the geometric dependency of each lake on glacial runoff. For example, there are ten lakes with direct glacial runoff from at least 240 km2 of glacier. Three case studies, including one of the well-studied Nam Tso Lake, demonstrate how the geometric dependency of a lake on glacial runoff can be directly linked to hydrological processes.

  11. Geometric dependency of Tibetan lakes on glacial runoff

    Directory of Open Access Journals (Sweden)

    V. H. Phan

    2013-01-01

    Full Text Available The Tibetan plateau is an essential source of water for South-East Asia. The run-off from its ~ 34 000 glaciers, which occupy an area of ~ 50 000 km2, feed Tibetan lakes and major Asian rivers like Indus and Brahmaputra. Reported glacial shrinkage likely has its impact on the run-off. Unfortunately, accurate quantification of glacial changes is difficult over the high relief Tibetan plateau. However, it has been recently shown that it is possible to directly assess water level changes of a significant part of the ~ 900 Tibetan lakes greater than one square kilometer. This paper exploits different remote sensing products to explicitly create links between Tibetan glaciers, lakes and rivers. The results allow us first to differentiate between lakes with and without outlet. In addition, we introduce the notion of geometric dependency of a lake on glacial runoff, defined as the ratio between the total area of glaciers draining into a lake and the area of the catchment of the lake. These dependencies are determined for all ~ 900 Tibetan lakes. To obtain these results, we combine the so-called CAREERI glacier mask, a lake mask based on the MODIS MOD44W water product and the HydroSHEDS river network product derived from SRTM elevation data. Based on a drainage network analysis, all drainage links between glaciers and lakes are determined. The results show that 25.3% of the total glacier area directly drains into one of 244 Tibetan lakes. The results also give the geometric dependency of each lake on glacial runoff. For example, there are 10~lakes with direct glacial runoff from at least 240 km2 of glacier. Three case studies, including one over the well-studied Nam Tso, demonstrate how the geometric dependency of a lake on glacial runoff can be directly linked to hydrological processes.

  12. 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....... On the basis of this decay, the analysed mountain regions fall within three distinct groupsprimarily reflecting variations in average values of rock columnuplift rates.Mountain ranges affected by rapid rock column uplift display high above-snowline relief and large decay lengths, whereas inactive orogens have...

  13. Pectus excavatum in mummies from ancient Egypt.

    Science.gov (United States)

    Kwiecinski, Jakub

    2016-12-01

    Pectus excavatum is one of the common congenital anomalies, yet there seems to be a suspicious absence of any cases or descriptions of this deformity from antiquity. This could represent a real change in disease prevalence but is more likely just due to an inadequate reporting in medico-historical literature. The current study reviews reports of computed tomography (CT) scans of 217 ancient Egyptian mummies, revealing 3 presumed cases of this deformity. Therefore, pectus excavatum was in fact present already in ancient times, with prevalence roughly similar to the modern one.

  14. Symmetries in Images on Ancient Seals

    CERN Document Server

    Sparavigna, Amelia

    2008-01-01

    In this paper, we discuss the presence of symmetries in images engraved on ancient seals, in particular on stamp seals. Mainly used to secure the containers from tampering and for owner's identification, these objects appeared during the 5th millennium BC in Mesopotamia. Usually the seals were engraved with simple images, suitable to communicate an immediate information. Rotational symmetries are already displayed by the most ancient stamp seals, whose images reach a quasi-perfect symmetry in their small circular or ovoid spaces. Bilateral symmetries are quite common in Egyptian scarab seals.

  15. Automatic indexing and reformulation of ancient dictionaries

    OpenAIRE

    Belaïd, Abdel; Turcan, Isabelle; Pierrel, Jean-Marie; Belaïd, Yolande; Rangoni, Yves; Hadjamar, Hassen

    2004-01-01

    International audience; This paper is related to automatic indexing and reformu-lation of ancient dictionaries. The objective is to make easy the access to ancient printed documents from XVI to XIX century for a diversified public (historians, scien-tists, librarians, etc.). Since the facsimile mode is insuffi-cient, the aim is to look further for the use of the index-ing based on the formal structure representative of some contents in order to optimize their exploration. Starting from a firs...

  16. Mythological Emblem Glyphs of Ancient Maya Kings

    DEFF Research Database (Denmark)

    Helmke, Christophe

    2012-01-01

    Heinrich Berlin’s identification of Emblem Glyphs in 1958 has rightly been hailed as one of the major breakthroughs in the decipherment of ancient Maya writing. Although their exact function and meaning was unclear at the time, these are now recognized to serve as exalted regal titles that incorp......Heinrich Berlin’s identification of Emblem Glyphs in 1958 has rightly been hailed as one of the major breakthroughs in the decipherment of ancient Maya writing. Although their exact function and meaning was unclear at the time, these are now recognized to serve as exalted regal titles...

  17. A Modern Take on an Ancient Master

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A new English translation of The Analects gives a fresh perspective on Confucius and his philosophy by Zan Jifang Confucius(551-491 B.C.) is generally viewed as ancient China’s foremost thinker.His philosophy is probably best catalogued in The Analects,a record of the sage’s wisdom compiled after his death.This Confucian classic provides a shortcut to understanding Chinese culture. A new English edition of the ancient classic(published by the Foreign Languages Press)

  18. Evolution of medical education in ancient Greece

    Institute of Scientific and Technical Information of China (English)

    Emmanouil Pikoulis; Pavlos Msaouel; Efthimios D Avgerinos; Sofia Anagnostopoulou; Christos Tsigris

    2008-01-01

    @@ The study of ancient Greece is essential for the proper understanding of the evolution of modem Western medicine.An important innovation of classical Greek medicine was the development of a body of medical theory associated with natural philosophy,i.e.a strong secular tradition of free enquiry,or what would now be called "science" (Επιστημη).Medical education rests upon the ancient Greek foundations and its history remains a fascinating topic for modem physicians and medical teachers.

  19. Managing the effects of accelerated glacial melting on volcanic collapse and debris flows: Planchon-Peteroa Volcano, Southern Andes

    Science.gov (United States)

    Tormey, Daniel

    2010-11-01

    Glaciated mountains are among the most sensitive environments to climatic changes, and recent work has shown that large-scale glacial melting, including at the end of the Pleistocene, caused a significant increase in the incidence of large volcanic sector collapse and debris flows on then-active volcanoes. With current accelerated rates of glacial melting, glaciated active volcanoes are at an increasing risk of sector collapse, debris flow and landslide. These catastrophic events are Earth's most damaging erosion phenomenon, causing extensive property damage and loss of life. This paper illustrates these effects in well-studied settings, focusing on the end-Pleistocene to Holocene glaciovolcanic growth and destruction of the cone of the active volcano Planchon-Peteroa in the Andean Southern Volcanic Zone at latitude 35° 15' S, along the border between Chile and Argentina. The development of the volcano over the last 14,000 years illustrates how glacial melting and magmatic activity can trigger landslides and sector collapses. Planchon had a large sector collapse that produced a highly mobile and erosive debris avalanche 11,000 years BP, and other slope instabilities during the end-Pleistocene/early Holocene deglaciation. The summit amphitheater left after the sector collapse was subject to alternating periods of glaciation and melting-induced lake formation. Breaching of the moraine dams then formed lahars and landslides originating at the western edge of the summit amphitheater, and the deposits are preserved along the western flank of the volcano. Deep incision of moraine deposits further down the western slope of the volcano indicates that the lahars and landslides were water-rich and had high erosive power. As illustrated by Planchon-Peteroa, the interplay among glacial growth and melting, magmatic activity, and slope stability is complex, but must be accounted for in volcanic hazard assessment. Planchon-Peteroa currently has the southernmost temperate zone

  20. Paleoenvironmental change in central Chile as inferred from OSL dating of ancient coastal sand dunes

    Science.gov (United States)

    Andrade, Belisario; Garcia, Juan L.; Lüthgens, Christopher; Fiebig, Markus

    2013-04-01

    To present day, the climatic and geographic expression of glacials and interglacials in the semiarid coast of central Chile remains unclear. The lack of well dated paleoclimatic records has up to now precluded firm conclusions whether maximum glacials evident in the Andes mountain range probably coincide with wetter (e.g., pluvials) or drier conditions at the coast. The natural region locally known as "Norte Chico" represents a transitional semiarid area between the extreme Atacama Desert to the North and the wetter, Mediterranean-like type of climate, to the South. In this semiarid region of Chile several generations of eolian sand dunes, some of them separated by paleosoils, have been preserved. In addition to the occurrence of paleosoils, thick debris flow deposits in some places overly ancient dune bodies, likely indicating significant environmental changes during the formation of these archives. However, the exact timing of these processes within the mid to late Pleistocene and Holocene is still unclear. A key aspect is that some of the ancient dunes are recently hanging above rocky coastlines, where no supply of sand exists today, likely implying their formation during a lower than present, probably glacio-eustatically induced sea level. The location of the research area in a key mid-latitude region of the eastern Pacific in combination with the preserved landform record offers a chance to reconstruct climatic shifts during the Quaternary by studying the variability of morphogenetic conditions throughout time, in order to promote knowledge about possible forcing factors driving climatic variability. Within this pilot study, samples for optically stimulated luminescence (OSL) dating were taken from three different stratigraphic sections that denote a complex environmental variability as indicated by paleosoils and debris flow units intercalated in ancient sand dunes. First dating results inferred from OSL measurements using a post-IR IRSL (pIRIR) protocol for

  1. Environmental transformations and cultural changes: A multidisciplinary case study for the Late Glacial and Final Palaeolithic from Northern Germany

    Science.gov (United States)

    Turner, F.; Tolksdorf, J. F.; Viehberg, F.; Schwarz, A.; von Bramann, U.; Bittmann, F.; Kaiser, K.; Schwalb, A.; Staesche, U.; Breest, K.; Pott, R.; Veil, S.

    2012-04-01

    In contrast to younger periods, studies integrating archaeological and environmental records for the Palaeolithic are still rare. Especially our knowledge about interactions between the drastic climatic/environmental changes and cultural developments during the Late Glacial is very limited. This multidisciplinary case study from river Jeetzel, a western Elbe tributary in Northern Germany, combines high resolution palaeoenvironmental investigations with fine-scaled archaeological research on stratified and surface sites. Various dating methods (palynostratigraphy, radiocarbon- and OSL-dating) and analyses of environmental and climatological proxies (pollen and plant macro-remains, ostracods, diatoms and green algae) on river palaeochannel sediments allow detailed reconstruction of interactions between Late Glacial climate, vegetation and fluvial developments. Biostratigraphical analyses on stratified archaeological sites and dating of charcoal / bone fragments from artefact scatters place the Late Palaeolithic occupation of Early Federmesser groups in an environmental context. Thus the former production of hitherto unknown amber art (amongst others a figurine representing a moose) can be ascribed to the Older Dryas and Early Allerød, which are the periods of main Late Glacial afforestation. Therewith our investigations suggest that Final Palaeolithic cultural changes may have been triggered by climatic and environmental transformations.

  2. Glacial erosion dynamics in a small mountainous watershed (Southern French Alps): A source-to-sink approach

    Science.gov (United States)

    Bonneau, Lucile; Toucanne, Samuel; Bayon, Germain; Jorry, Stéphan J.; Emmanuel, Laurent; Silva Jacinto, Ricardo

    2017-01-01

    In this study we used major element composition, neodymium isotopes ratios (εNd) and concentration of REE to track and quantify the sediment routing in the Var sedimentary system from source (Southern French Alps) to sink (Ligurian Sea) over the last 50 ka. Our data reveal that changes in sediment sources over that period, associated with concomitant changes in the hyperpycnal (i.e. flood-generated turbidity currents) activity in the Var submarine canyon, were mainly driven by paleoenvironmental conditions in the upper basin and in particular by the presence of glaciers during the last glacial period. Based on this evidence, we determined when and how glacier-derived sediments were produced, then excavated and transferred to the ocean, allowing us to ultimately tune offshore sedimentary records to onshore denudation rates. In contrast to large glaciated systems, we found that sediment export from the Var River to the Mediterranean Sea directly responded to climate-induced perturbations within the basin. Finally, we estimated that sediment fluxes in the Var routing system were 2.5 times higher during the Last Glacial Maximum than today, thus confirming that glacier denudation rates exceed fluvial rates and that such a pattern also governs the interglacial-glacial sediment flux cycle in other small mountainous basins.

  3. Paleoclimate Simulations of the Mid-Holocene and Last Glacial Maximum by FGOALS

    Institute of Scientific and Technical Information of China (English)

    ZHENG Weipeng; YU Yongqiang

    2013-01-01

    Paleoclimate simulations of the mid-Holocene (MH) and Last Glacial maximum (LGM) by the latest versions of the Flexible Global Ocean-Atmosphere-Land System model,Spectral Version 2 and Grid-point Version 2 (FGOALS-s2 and g2) are evaluated in this study.The MH is characterized by changes of insolation induced by orbital parameters,and the LGM is a glacial period with large changes in greenhouse gases,sea level and ice sheets.For the MH,both versions of FGOALS simulate reasonable responses to the changes of insolation,such as the enhanced summer monsoon in African-Asian regions.Model differences can be identified at regional and seasonal scales.The global annual mean surface air temperature (TAS) shows no significant change in FGOALS-s2,while FGOALS-g2 shows a global cooling of about 0.7℃ that is related with a strong cooling during boreal winter.The amplitude of ENSO is weaker in FGOALS-g2,which agrees with proxy data.For the LGM,FGOALS-g2 captures the features of the cold and dry glacial climate,including a global cooling of 4.6℃ and a decrease in precipitation by 10%.The ENSO is weaker at the LGM,with a tendency of stronger ENSO cold events.Sensitivity analysis shows that the Equilibrium Climate Sensitivity (ECS) estimated for FGOALS ranges between 4.23℃ and 4.59℃.The sensitivity of precipitation to the changes of TAS is ~2.3% ℃-1,which agrees with previous studies.FGOALS-g2 shows better simulations of the Atlantic Meridional Overturning Circulation (AMOC) and African summer monsoon precipitation in the MH when compared with FGOALS-g1.0; however,it is hard to conclude any improvements for the LGM.

  4. Records of solar eclipse observations in ancient China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Like ancient people at other places of the world, the ancient Chinese lived in awe of the Sun. As they felt solar eclipses extremely significant events, they closely observed the occurrence of solar eclipse. Ancient astronomers further realized very early that solar eclipses were one of the important astronomical phenomena to revise and improve the ancient calendar. Interestingly, ancient emperors regarded solar eclipses as warnings from heaven that might affect the stability of their throne. Consequently, observing and recording solar eclipses became official, which dated far back to ancient China when numerous relevant descriptions were recorded in historical books. These records contribute substantially to China as an ancient civilization, as well as to the research of the long-term variation of the rotation rate of the Earth during >2000 years before the 17th century. This paper briefly reviews the perception, observations and recording of solar eclipses by ancient Chinese astronomers.

  5. Records of solar eclipse observations in ancient China

    Institute of Scientific and Technical Information of China (English)

    HAN YanBen; QIAO OiYuan

    2009-01-01

    Like ancient people at other places of the world, the ancient Chinese lived in awe of the Sun. As they felt solar eclipses extremely significant events, they closely observed the occurrence of solar eclipse. Ancient astronomers further realized very early that solar eclipses were one of the important astro-nomical phenomena to revise and improve the ancient calendar. Interestingly, ancient emperors re-garded solar eclipses as warnings from heaven that might affect the stability of their throne. Conse-quently, observing and recording solar eclipses became official, which dated far back to ancient China when numerous relevant descriptions were recorded in historical books. These records contribute substantially to China as an ancient civilization, as well as to the research of the long-term variation of the rotation rate of the Earth during >2000 years before the 17th century. This paper briefly reviews the perception, observations and recording of solar eclipses by ancient Chinese astronomers.

  6. Periodicity, the Canon and Sport

    Directory of Open Access Journals (Sweden)

    Thomas F. Scanlon

    2015-10-01

    Full Text Available The topic according to this title is admittedly a broad one, embracing two very general concepts of time and of the cultural valuation of artistic products. Both phenomena are, in the present view, largely constructed by their contemporary cultures, and given authority to a great extent from the prestige of the past. The antiquity of tradition brings with it a certain cachet. Even though there may be peripheral debates in any given society which question the specifics of periodization or canonicity, individuals generally accept the consensus designation of a sequence of historical periods and they accept a list of highly valued artistic works as canonical or authoritative. We will first examine some of the processes of periodization and of canon-formation, after which we will discuss some specific examples of how these processes have worked in the sport of two ancient cultures, namely Greece and Mesoamerica.

  7. Kame deltas provide evidence for a new glacial lake and suggest early glacial retreat from central Lower Michigan, USA

    Science.gov (United States)

    Schaetzl, Randall J.; Lepper, Kenneth; Thomas, Sarah E.; Grove, Leslie; Treiber, Emma; Farmer, Alison; Fillmore, Austin; Lee, Jordan; Dickerson, Bethany; Alme, Kayleigh

    2017-03-01

    In association with an undergraduate Honors Seminar at Michigan State University, we studied two small kame deltas in north-central Lower Michigan. These recently identified deltas provide clear evidence for a previously unknown proglacial lake (Glacial Lake Roscommon) in this large basin located in an interlobate upland. Our first goal was to document and characterize the geomorphology of these deltas. Because both deltas are tied to ice-contact ridges that mark the former position of the retreating ice margin within the lake, our second goal was to establish the age of one of the deltas, thereby constraining the timing of ice retreat in this part of Michigan, for which little information currently exists. Both deltas are composed of well-sorted fine and medium sands with little gravel, and have broad, nearly flat surfaces and comparatively steep fronts. Samples taken from the upper 1.5 m of the deltas show little spatial variation in texture, aside from a general fining toward their outer margins. Gullies on the outer margins of both deltas probably postdate the formation of the deltas proper; we suggest that they formed by runoff during a permafrost period, subsequent to lake drawdown. We named the ice lobe that once covered this area the Mackinac Lobe, because it had likely advanced into the region across the Mackinac Straits area. Five of six optically stimulated luminescence (OSL) ages from one of the deltas had minimal scatter and were within ± 1000 years of one another, with a mean age of 23.1 ± 0.4 ka. These ages suggest that the Mackinac Lobe had started to retreat from the region considerably earlier than previously thought, even while ice was near its maximum extent in Illinois and Indiana, and the remainder of Michigan was ice-covered. This early retreat, which appears to coincide with a short-lived warm period indicated from the Greenland ice core, formed an "opening" that was at least occasionally flooded. Thick and deep, fine-textured deposits

  8. Oskarshamn site investigation. Searching for evidence of late- or post-glacial faulting in the Oskarshamn region. Results from 2004

    Energy Technology Data Exchange (ETDEWEB)

    Lagerbaeck, Robert; Sundh, Martin; Svantesson, Sven-Ingemund; Svedlund, Jan-Olov [Geological Survey of Sweden (SGU), Uppsala (Sweden)

    2005-11-15

    level, they must have been raised above the ancient sea fairly soon after the deposition of sediments. Consequently, the deposits were completely waterlogged and susceptible to liquefaction only during a limited period of time. The most remarkable observation made during the stratigraphical investigations was the occurrence of slide deposits at Faarbosjoen, near Simpevarp. It was not possible to date the sliding in any of the trenches but, as the slide deposits were covered with beach sand, sliding must have occurred some time between deglaciation and the upheaval above the sea, some 11,000 years ago. It is an open question whether the sliding occurred spontaneously due solely to loading, or whether the phenomenon was triggered by an external event. Hypothetically this may have been moderately strong earthquakes in the vicinity or more distant earthquakes of greater magnitude. The frequent occurrence of periglacial features in those parts of the investigation area located above the sea during the Younger Dryas period some 12,000 years ago suggests that frost processes must be seriously considered as an alternative to seismically induced liquefaction when deformed sediments are encountered.

  9. Molecular evidence for ancient asexuality in timema stick insects.

    Science.gov (United States)

    Schwander, Tanja; Henry, Lee; Crespi, Bernard J

    2011-07-12

    Asexuality is rare in animals in spite of its apparent advantage relative to sexual reproduction, indicating that it must be associated with profound costs [1-9]. One expectation is that reproductive advantages gained by new asexual lineages will be quickly eroded over time [3, 5-7]. Ancient asexual taxa that have evolved and adapted without sex would be "scandalous" exceptions to this rule, but it is often difficult to exclude the possibility that putative asexuals deploy some form of "cryptic" sex, or have abandoned sex more recently than estimated from divergence times to sexual relatives [10]. Here we provide evidence, from high intraspecific divergence of mitochondrial sequence and nuclear allele divergence patterns, that several independently derived Timema stick-insect lineages have persisted without recombination for more than a million generations. Nuclear alleles in the asexual lineages displayed significantly higher intraindividual divergences than in related sexual species. In addition, within two asexuals, nuclear allele phylogenies suggested the presence of two clades, with sequences from the same individual appearing in both clades. These data strongly support ancient asexuality in Timema and validate the genus as an exceptional opportunity to attack the question of how asexual reproduction can be maintained over long periods of evolutionary time.

  10. Dialogue Genre Texts in Ancient Greek Prose: Linguostylistic Aspect

    OpenAIRE

    Gita Bērziņa

    2011-01-01

    Dialogue Genre Texts in Ancient Greek Prose: Linguostylistic Aspect Doctoral thesis deals with the study of essential linguistic features of the Ancient Greek dialogue as an important ancient prose genre. The goal of the thesis is to disclose the specific linguistic characteristics of the genre of Ancient Greek dialogue on the basis of comparative analysis of the linguistic structure (on all levels as well as in style) of the texts of three most prominent authors (Plato, Xenoph...

  11. Fire usage and ancient hominin detoxification genes

    NARCIS (Netherlands)

    Aarts, Jac M.M.J.G.; Alink, Gerrit M.; Scherjon, Fulco; MacDonald, Katharine; Smith, Alison C.; Nijveen, Harm; Roebroeks, Wil

    2016-01-01

    Studies of the defence capacity of ancient hominins against toxic substances may contribute importantly to the reconstruction of their niche, including their diets and use of fire. Fire usage implies frequent exposure to hazardous compounds from smoke and heated food, known to affect general heal

  12. Discovering the Ancient Maya from Space

    Science.gov (United States)

    Sever, T. L.

    2008-01-01

    The Pet6n region of northern Guatemala contains some of the most significant Mayan archeological sites in Latin America. It was in this region that the Maya civilization began, flourished, and abruptly disappeared. Remote sensing technology is helping to locate and map ancient Maya sites that are threatened today by accelerating deforestation and looting. Thematic Mapper, IKONOS, and QuickBird satellite, and airborne STAR-3i and AIRSAR radar data, combined with Global Positioning System (GPS) technology, are successfully detecting ancient Maya features such as sites, roadways, canals, and water reservoirs. Satellite imagery is also being used to map the bajos, which are seasonally flooded swamps that cover over 40% of the land surface. Through the use of various airborne and satellite sensor systems we have been able to detect and map ancient causeways, temples, reservoirs, and land forms, and locate these features on the ground through GPS technology. Recently, we have discovered that there is a strong relationship between a tropical forest vegetation signature in satellite imagery and the location of archeological sites. We believe that the use of limestone and lime plasters in ancient Maya construction affects the moisture, nutrition, and plant species of the surface vegetation. We have mapped these vegetation signatures in the imagery and verified through field survey that they are indicative of archeological sites. Through the use of remote sensing and GIS technology it is possible to identify unrecorded archeological features in a dense tropical forest environment and monitor these cultural features for their protection.

  13. Ancient bronze disks, decorations and calendars

    CERN Document Server

    Sparavigna, Amelia Carolina

    2012-01-01

    Recently, it was published that some ancient bronze disks could had been calendars, that is, that their decorations had this function. Here I am discussing an example, the disk of the Trundholm Sun Chariot, proposing a new interpretation of it, giving a calendar of 360 days. Some geometric diagrams concerning the decoration layout are also proposed.

  14. Ancient DNA analysis of dental calculus.

    Science.gov (United States)

    Weyrich, Laura S; Dobney, Keith; Cooper, Alan

    2015-02-01

    Dental calculus (calcified tartar or plaque) is today widespread on modern human teeth around the world. A combination of soft starchy foods, changing acidity of the oral environment, genetic pre-disposition, and the absence of dental hygiene all lead to the build-up of microorganisms and food debris on the tooth crown, which eventually calcifies through a complex process of mineralisation. Millions of oral microbes are trapped and preserved within this mineralised matrix, including pathogens associated with the oral cavity and airways, masticated food debris, and other types of extraneous particles that enter the mouth. As a result, archaeologists and anthropologists are increasingly using ancient human dental calculus to explore broad aspects of past human diet and health. Most recently, high-throughput DNA sequencing of ancient dental calculus has provided valuable insights into the evolution of the oral microbiome and shed new light on the impacts of some of the major biocultural transitions on human health throughout history and prehistory. Here, we provide a brief historical overview of archaeological dental calculus research, and discuss the current approaches to ancient DNA sampling and sequencing. Novel applications of ancient DNA from dental calculus are discussed, highlighting the considerable scope of this new research field for evolutionary biology and modern medicine.

  15. Tapping Ancient Roots: Plaited Paper Baskets

    Science.gov (United States)

    Patrick, Jane

    2011-01-01

    With ancient roots, basket making has been practiced since the earliest civilizations, and according to textile experts, probably pre-dates pottery. This is partly conjecture since few baskets remain. It is through evidence found in clay impressions that the earliest baskets reveal themselves. Basically, basketry construction is like flat weaving.…

  16. Ancient Pyramids Help Students Learn Math Concepts

    Science.gov (United States)

    Smith, Courtney D.; Stump, Amanda M.; Lazaros, Edward J.

    2010-01-01

    This article presents an activity that allows students to use mathematics and critical-thinking skills to emulate processes used by the ancient Egyptians to prepare the site for the Pyramids of Giza. To accomplish this, they use three different methods. First, they create a square using only simple technological tools that were available to the…

  17. Ancient whole grain gluten-free flatbreads

    Science.gov (United States)

    The USDA food guide recommends that at least ½ of all the grains eaten should be whole grains. The FDA allows food Health Claim labels for food containing 51% whole gains and 11 g of dietary fiber. This is the only report demonstrating innovative ancient whole grain gluten-free (no yeast or chemical...

  18. An ancient musical instrument returns home

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    After 300 years abroad, an ancient Chinese musical instrument returned home with its face lifted and a Japanese name. Originally a one-stringed plucker, the Daisho Modo now features a whole family of electric high-, medium-pitched and bass instruments. With crisp tone and wide range, the Daisho Modo is

  19. Fossil avian eggshell preserves ancient DNA

    DEFF Research Database (Denmark)

    Oskam, Charlotte L; Haile, James Seymour; McLay, Emma

    2010-01-01

    Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful...

  20. The Study of Women in Ancient Society.

    Science.gov (United States)

    Moscovich, M. James

    1982-01-01

    Presents ideas for teaching about the roles of women in ancient Greek and Roman societies for undergraduate history and sociology classes. The discussion covers the roots of misogyny in Western culture, parallels between mythologies and sociocultural patterns, and the legal status of women in antiquity. (AM)

  1. [Ancient tattooing from today's point of view].

    Science.gov (United States)

    Zimmermann, R; Zimmermann, K

    1981-06-01

    Both literary and arachaeological evidence indicates that, up to now, ancient tattoos can be traced with certainty in painting only among Thracians. A comparison with modern tattoos reveals differences of motivation and motifs, whereas localization, technique, and removal show similarities. The illustrations demonstrate some tattoos typical for Thracians on Greek vases.

  2. Case report 872. "Ancient" schwannoma (degenerated neurilemoma).

    Science.gov (United States)

    Schultz, E; Sapan, M R; McHeffey-Atkinson, B; Naidich, J B; Arlen, M

    1994-10-01

    A case of an ancient schwannoma was presented. The rare occurrence of this tumor has resulted in only a few reported cases with descriptions of its features on imaging. Our patient's tumor, like one previously reported case, demonstrated calcification on the plain film - a finding not associated with other histologic types of schwannomas. Angiography revealed the tumor to be hypervascular. Evaluation by MRI demonstrated a lobulated, encapsulated soft tissue mass containing several cystic areas that corresponded histologically to areas of necrosis. Hypertrophied blood vessels were seen in the periphery of the tumoral mass. Too few ancient schwannomas have been reported to conclude whether or not radiographic evidence of soft tissue calcification is characteristic of this histologically distinctive subtype of schwannoma. However, since calcification is seen histologically as part of the degenerating process, its presence on plain films could be a feature of this tumor. Furthermore, the presence of cystic areas on MRI is not surprising given the pathological changes that occur in this tumor. We suggest that a diagnosis of ancient schwannoma be considered when a patient presents with a hypervascular soft tissue mass containing amorphous calcification on plain films and cystic areas on MRI. Despite the nonspecificity of these imaging findings, this point is relevant because each of these features suggests the presence of a malignant mass. Awareness of the possibility of a benign ancient schwannoma could obviate unnecessary radical surgery.

  3. Communication Arts in the Ancient World.

    Science.gov (United States)

    Havelock, Eric A., Ed.; Hershbell, Jackson P., Ed.

    Intended for both classicists and nonclassicists, this volume explores the beginnings of literacy in ancient Greece and Rome and examines the effects of written communication on these cultures. The nine articles, written by classical scholars and educators in the field of communication, discuss the following: the superiority of the alphabet over…

  4. Paragons of Education in Ancient Times

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    MOTHERS contributed greatly to children’s education in ancient China long before schools took shape. Behind many prominent figures lay greatmothers whose personal example and verbal instruction benefited their children throughout life. There is an old sayingabout the "stern father and compassionate mother."However, you will always

  5. The Roots of Science in Ancient China.

    Science.gov (United States)

    Fisher, Arthur

    1982-01-01

    A 45-year-old research project (culminating in the multivolume "Science and Civilization in China") is examining major scientific innovations in ancient China and attempting to explain why, although the Chinese gained a technological edge in the past, they did not make the forward leap into modern science. (JN)

  6. The Challenges of Qualitatively Coding Ancient Texts

    Science.gov (United States)

    Slingerland, Edward; Chudek, Maciej

    2012-01-01

    We respond to several important and valid concerns about our study ("The Prevalence of Folk Dualism in Early China," "Cognitive Science" 35: 997-1007) by Klein and Klein, defending our interpretation of our data. We also argue that, despite the undeniable challenges involved in qualitatively coding texts from ancient cultures, the standard tools…

  7. Mitochondrial phylogenomics of modern and ancient equids

    DEFF Research Database (Denmark)

    Vilstrup, Julia T; Seguin-Orlando, Andaine; Stiller, Mathias;

    2013-01-01

    to calibrate reliable molecular clocks. Additional mitochondrial genome sequence data, including radiocarbon dated ancient equids, will be required before revisiting the exact timing of the lineage radiation leading up to modern equids, which for now were found to have possibly shared a common ancestor as far...

  8. Vulnerability assessment of Glacial Lake Outburst Floods using Remote Sensing and GIS in North Sikkim (India), Eastern Himalaya

    Science.gov (United States)

    Aggarwal, Suruchi; Probha Devi, Juna; Thakur, Praveen Kumar; Rai, Suresh Chand

    2016-04-01

    Glacial lake outburst floods (GLOFs) occur when glacier melt water dammed by a moraine is released in short time. Such floods may lead to disastrous events posing, therefore, a huge threat to human lives and infrastructure. A devastating GLOF in Uttarakhand, India, on 17 July 2013 has led to the loss of all villages in a stretch of 18 km downstream the lake and the loss of more than 5000 lives. The present study evaluates all 16 glacial lakes (with an area >0.1 km²) in the Thangu valley, northern Sikkim (India), eastern Himalaya, with respect to potential threats for the downstream areas. The hazard criteria for the study include slope, aspect and distance of the respective parent glacier, change in the lake area, dam characteristics and lake depth. For the most hazardous lakes, the socio-economic conditions in the downstream areas (settlements and infrastructure) are analysed regarding the impact of potential GLOFs. For the vulnerability analysis, we used various satellite products including LANDSAT, RESOUCESAT-1 and 2, RISAT-1 imageries and ASTER GDEM covering the period from 1977 to 2014. For lake mapping, we applied the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Snow Index (NDSI). A Land Use Land Cover (LULC) map of the study area showing in-situ observations is serving as driving factor for the vulnerability analysis. The results of the study show that almost all evaluated glacial lakes were expanding during the study period (1977-2014). Combining the hazard criteria for the lakes, 5 of the 16 studied glacial lakes are identified as highly hazardous. In the downstream area, there are two villages with 200 inhabitants and an army camp within the zone of highest vulnerability. The identified vulnerability zones may be used by the local authorities to take caution of the threatened villages and infrastructure and for risk analysis for planned future hydropower plants.

  9. Climate Change, Glacier Retreat and Sediment Waves: Evidences from Fans in the Fox Glacial valley (New Zealand) and Analogical Modeling

    Science.gov (United States)

    Gomez, C. A.; Purdie, H.

    2015-12-01

    As global climate continues warm, mountain environments are changing, and rates of glacial retreat are unprecedented. The hydrologic implications of this rapid ice retreat and changing climate conditions have been the focus of numerous studies, but the consequent effects on the sediment cascade in valleys and tributaries has received considerably less attention. In the present study, we investigated the role of glacial recession on sediment mobilization and deposition in a mountain valley catchment at Fox Glacier, New Zealand. In particular, we analyze the role of glacier recession on the formation of sediment fans in the main valley. Emphasis was put on the role of sediment, impounded by the glacier in side tributaries, becoming rapidly available for remobilization as the glacier retreats. The method is based on field observations, and measurements using high resolution GNSS (Trimble R8 survey grade differential GNSS) and photogrammetric methods using Structure from Motion based on ground-, helicopter- and UAV- photographs. Field observations were conducted in the period 2014 - 2015, and have been complimented with analogic modeling in the laboratory, in order to comprehend the processes driving rapid fan formation. The analogic model reproduced the retreat of the glacier and the response of a tributary, with simulations for both glaciated and de-glaciated conditions. For similar hydrologic and slope parameters, the fans created after glacial retreat have shown an acceleration in their formation of up to 12 times compared to fanes created without glacial influence. Field observations within the period 2013 - 2015 of Straight Creek Fan (Fox Valley, New Zealand) have confirmed laboratory simulations, with the fan growing to a radius superior to 200 m and a valley-long width superior to 450 m. As glaciers continue to retreat, it can be expected that sediment surges will occur in affected valleys, without the requirements of other forcing like earthquake or extreme

  10. Ancient Egyptian Medicine: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Samuel Adu-Gyamfi

    2015-12-01

    Full Text Available Our present day knowledge in the area of medicine in Ancient Egypt has been severally sourced from medical papyri several of which have been deduced and analyzed by different scholars. For educational purposes it is always imperative to consult different literature or sources in the teaching of ancient Egypt and medicine in particular. To avoid subjectivity the author has found the need to re-engage the efforts made by several scholars in adducing evidences from medical papyri. In the quest to re-engage the efforts of earlier writers and commentaries on the medical papyri, we are afforded the opportunity to be informed about the need to ask further questions to enable us to construct or reconstruct both past and modern views on ancient Egyptian medical knowledge. It is this vocation the author sought to pursue in the interim, through a preliminary review, to highlight, comment and reinvigorate in the reader or researcher the need for a continuous engagement of some pertinent documentary sources on Ancient Egyptian medical knowledge for educational and research purposes. The study is based on qualitative review of published literature. The selection of those articles as sources was based on the focus of the review, in order to purposively select and comment on articles that were published based either on information from a medical papyrus or focused on medical specialization among the ancient Egyptians as well as ancient Egyptian knowledge on diseases and medicine. It was found that the Egyptians developed relatively sophisticated medical practices covering significant medical fields such as herbal medicine, gynecology and obstetrics, anatomy and physiology, mummification and even the preliminary form of surgery. These practices, perhaps, were developed as remedies for the prevailing diseases and the accidents that might have occurred during the construction of their giant pyramids. It must be stated that they were not without flaws. Also, the

  11. Glacial isostatic adjustment in the static gravity field of Fennoscandia

    NARCIS (Netherlands)

    Root, B.C.; Van der Wal, W.; Novak, P.; Ebbing, J.; Vermeersen, L.L.A.

    2015-01-01

    In the central part of Fennoscandia, the crust is currently rising, because of the delayed response of the viscous mantle to melting of the Late Pleistocene ice sheet. This process, called Glacial Isostatic Adjustment (GIA), causes a negative anomaly in the present-day static gravity field as isosta

  12. Glacial sedimentation in the late precambrian bebedouro formation, Bahia, Brazil

    Science.gov (United States)

    Montes, A. S. L.; Gravenor, C. P.; Montes, M. L.

    1985-07-01

    The possibility that diamictites of the Late Precambrian Bebedouro Formation of northern Bahia, Brazil, are glacial in origin has been based on the areal extent, diversity of the lithology of the stones and the presence of outsize dropstones in rhythmites. More detailed studies on the diamictites show that some of the stones are faceted and their shapes are typical of those developed by glacial transport. Additionally, a small abraded pavement is described and garnets found in the matrix of the diamictite have chattermark trails. Taken in aggregrate, these observations suggest a glacial origin for the Bebedouro Formation. In the study area, the texture of the diamictites range from stone-rich to siltstones containing sporadic stones. The stone-rich diamictites are commonly found in layers, up to a metre in thickness, separated by poorly laminated siltstone. The Formation probably was deposited in a large lake or sea and the layered diamictites are debris flows which were derived from uneven piles of glacial debris deposited on the floor of the lake or sea.

  13. Periglacial and glacial landforms in western part of Pohorje Mountains

    Directory of Open Access Journals (Sweden)

    Jaroslav Obu

    2011-12-01

    Full Text Available Recent geomorphological research in eastern part of Pohorje Mountains has revealed new information about periglacial and glacial landforms of that area. Based on these findings, similar landforms in western part of Pohorje were studied, especially cryoplanation terraces and nivation hollows. Field research has also revealed the existence of ploughing rocks, blockstreams, blockfields and one cirque.

  14. 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 South-East Asia. The run-off from its ~ 34 000 glaciers, which occupy an area of ~ 50 000 km2, feed Tibetan lakes and major Asian rivers like Indus and Brahmaputra. Reported glacial shrinkage likely has its impact on the run-off. Unfortunately,

  15. 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,

  16. Glacial melting: an overlooked threat to Antarctic krill.

    Science.gov (United States)

    Fuentes, Verónica; Alurralde, Gastón; Meyer, Bettina; Aguirre, Gastón E; Canepa, Antonio; Wölfl, Anne-Cathrin; Hass, H Christian; Williams, Gabriela N; Schloss, Irene R

    2016-06-02

    Strandings of marine animals are relatively common in marine systems. However, the underlying mechanisms are poorly understood. We observed mass strandings of krill in Antarctica that appeared to be linked to the presence of glacial meltwater. Climate-induced glacial meltwater leads to an increased occurrence of suspended particles in the sea, which is known to affect the physiology of aquatic organisms. Here, we study the effect of suspended inorganic particles on krill in relation to krill mortality events observed in Potter Cove, Antarctica, between 2003 and 2012. The experimental results showed that large quantities of lithogenic particles affected krill feeding, absorption capacity and performance after only 24 h of exposure. Negative effects were related to both the threshold concentrations and the size of the suspended particles. Analysis of the stomach contents of stranded krill showed large quantities of large particles ( > 10(6 )μm(3)), which were most likely mobilized by glacial meltwater. Ongoing climate-induced glacial melting may impact the coastal ecosystems of Antarctica that rely on krill.

  17. 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...

  18. The journey of discovering skull base anatomy in ancient Egypt and the special influence of Alexandria.

    Science.gov (United States)

    Elhadi, Ali M; Kalb, Samuel; Perez-Orribo, Luis; Little, Andrew S; Spetzler, Robert F; Preul, Mark C

    2012-08-01

    The field of anatomy, one of the most ancient sciences, first evolved in Egypt. From the Early Dynastic Period (3100 BC) until the time of Galen at the end of the 2nd century ad, Egypt was the center of anatomical knowledge, including neuroanatomy. Knowledge of neuroanatomy first became important so that sacred rituals could be performed by ancient Egyptian embalmers during mummification procedures. Later, neuroanatomy became a science to be studied by wise men at the ancient temple of Memphis. As religious conflicts developed, the study of the human body became restricted. Myths started to replace scientific research, squelching further exploration of the human body until Alexander the Great founded the city of Alexandria. This period witnessed a revolution in the study of anatomy and functional anatomy. Herophilus of Chalcedon, Erasistratus of Chios, Rufus of Ephesus, and Galen of Pergamon were prominent physicians who studied at the medical school of Alexandria and contributed greatly to knowledge about the anatomy of the skull base. After the Royal Library of Alexandria was burned and laws were passed prohibiting human dissections based on religious and cultural factors, knowledge of human skull base anatomy plateaued for almost 1500 years. In this article the authors consider the beginning of this journey, from the earliest descriptions of skull base anatomy to the establishment of basic skull base anatomy in ancient Egypt.

  19. The Ancient Kemetic Roots of Library and Information Science.

    Science.gov (United States)

    Zulu, Itibari M.

    This paper argues that the ancient people of Kemet (Egypt), "the black land," built and operated the first major libraries and institutions of higher education in the world. Topics of discussion include the Ancient Egyptians as an African people; a chronology of Ancient Kemet; literature in Kemet; a history of Egyptian Librarianship; the…

  20. Deep sequencing of RNA from ancient maize kernels

    DEFF Research Database (Denmark)

    Fordyce, Sarah Louise; Avila Arcos, Maria del Carmen; Rasmussen, Morten;

    2013-01-01

    The characterization of biomolecules from ancient samples can shed otherwise unobtainable insights into the past. Despite the fundamental role of transcriptomal change in evolution, the potential of ancient RNA remains unexploited - perhaps due to dogma associated with the fragility of RNA. We...... maize kernels. The results suggest that ancient seed transcriptomics may offer a powerful new tool with which to study plant domestication....

  1. 76 FR 50476 - Application To Export Electric Energy; Glacial Energy of Texas, Inc.

    Science.gov (United States)

    2011-08-15

    ... Application To Export Electric Energy; Glacial Energy of Texas, Inc. AGENCY: Office of Electricity Delivery.... (Glacial) has applied for authority to transmit electric energy from the United States to Mexico pursuant...)). On July 14, 2011, DOE received an application from Glacial for authority to transmit electric...

  2. Genetic diversity among ancient Nordic populations.

    Directory of Open Access Journals (Sweden)

    Linea Melchior

    Full Text Available Using established criteria for work with fossil DNA we have analysed mitochondrial DNA from 92 individuals from 18 locations in Denmark ranging in time from the Mesolithic to the Medieval Age. Unequivocal assignment of mtDNA haplotypes was possible for 56 of the ancient individuals; however, the success rate varied substantially between sites; the highest rates were obtained with untouched, freshly excavated material, whereas heavy handling, archeological preservation and storage for many years influenced the ability to obtain authentic endogenic DNA. While the nucleotide diversity at two locations was similar to that among extant Danes, the diversity at four sites was considerably higher. This supports previous observations for ancient Britons. The overall occurrence of haplogroups did not deviate from extant Scandinavians, however, haplogroup I was significantly more frequent among the ancient Danes (average 13% than among extant Danes and Scandinavians (approximately 2.5% as well as among other ancient population samples reported. Haplogroup I could therefore have been an ancient Southern Scandinavian type "diluted" by later immigration events. Interestingly, the two Neolithic samples (4,200 YBP, Bell Beaker culture that were typed were haplogroup U4 and U5a, respectively, and the single Bronze Age sample (3,300-3,500 YBP was haplogroup U4. These two haplogroups have been associated with the Mesolithic populations of Central and Northern Europe. Therefore, at least for Southern Scandinavia, our findings do not support a possible replacement of a haplogroup U dominated hunter-gatherer population by a more haplogroup diverse Neolithic Culture.

  3. Ancient Egypt in our Cultural Heritage?

    Directory of Open Access Journals (Sweden)

    Vera Vasiljević

    2016-02-01

    Full Text Available Inspiration derived from ancient Egypt is usually expressed through the Egyptian motifs in arts and popular culture of the 19th and 20th centuries, as well as through the non-scientific interpretations of the culture, very much based upon the Renaissance ones. The number and variety of material and non-material traces of this fascination are most expressed in the countries where, along with the early support for the institutional development of Egyptology, there existed economically potent educated middle classes (Western and Central Europe, USA, but may also be traced elsewhere. The public fascination by ancient Egypt has not ceased by the times of foundation of Egyptology, marked by the decipherment of the hieroglyphic script in 1822. Until the end of the 20th century Egyptologists have rarely dealt with the prelude to their discipline, limiting their interest to the critical approach to ancient sources and to noting the attempts to interpret the hieroglyphic script and the function of pyramids. However, the rising importance of the reception studies in other disciplines raised the interest of Egyptologists for the "fascination of Egypt", thus changing the status of various modes of expressing "Egyptomania" – they have thus become a part of the cultural heritage, registered, documented, preserved and studied. The research of this kind is only beginning in Serbia. The line of inquiry enhances the knowledge of the scope, manifestations and roles of the interest in Egypt, not limited by the national or political borders. On the other hand, the existence of the cultural heritage similar to the wider European view of ancient Egypt – short remarks by Jerotej Račanin, Kandor by Atanasije Stojković, the usage of architectural motifs derived from Egypt, the emergence of small private collections, to mention several early examples – all show that the research into the reception of ancient Egypt may contribute to the knowledge about the history

  4. Ancient and Medieval Cosmology in Armenian Highland

    Science.gov (United States)

    Farmanyan, Sona V.; Mickaelian, Areg M.

    2016-12-01

    Humankind has always sought to recognize the nature of various sky related phenomena and tried to give them explanations. It is especially vivid in ancient cultures, many of which are related to the Middle East. The purpose of this study is to identify ancient Armenian's pantheistic and cosmological perceptions, world view, notions and beliefs. By this study we answer the question "How did the Universe work in Ancient Armenian Highland?" The paper focuses on the structure of the Universe and many phenomena of nature that have always had major influence on ancient Armenians thinking. Here we weave together astronomy, anthropology and mythology of Armenia, and scientific thinking revealed in local astronomy traditions. The initial review of the study covers Moses of Khoren, Yeznik of Koghb, Anania Shirakatsi and other 5th-7th centuries historians' and scientists' records about the Universe related superstitious beliefs and cosmological understanding. By discussing and comparing Universe structure in various regional traditions, myths, folk songs and phraseological units we very often came across "seven worlds", "seven earths" and "seven layers" concepts. We draw parallels between scientific and mythological Earth and Heaven and thus find similar number of layers on both of the ancient and modern thinking. In the article we also give some details about the tripartite structure of the Universe and how these parts are connected with axis. This axis is either a column or a Cosmic Tree (Kenatz Tsar). In Armenian culture the preliminary meanings of the Kenatz Tsar are more vivid in folk songs (Jan gyulums), plays, epic, and so on, which was subsequently mixed with religious and spiritual views. We conclude that the perception of the Universe structure and celestial objects had a significant impact on culture and worldview of the people of the Armenian Highland; particularly it was one of the bases of the regional cultural diversity.

  5. Letter to the editor: Genetics and the archaeology of ancient Israel.

    Science.gov (United States)

    Brody, Aaron J; King, Roy J

    2013-12-01

    This letter is a call for DNA testing on ancient skeletal materials from the southern Levant to begin a database of genetic information of the inhabitants of this crossroads region. In this region, during the Iron I period traditionally dated to circa 1200-1000 BCE, archaeologists and biblical historians view the earliest presence of a group that called itself Israel. They lived in villages in the varied hill countries of the region, contemporary with urban settlements in the coastal plains, inland valleys, and central hill country attributed to varied indigenous groups collectively called Canaanite. The remnants of Egyptian imperial presence in the region lasted until around 1150 BCE, postdating the arrival of an immigrant group from the Aegean called the Philistines circa 1175 BCE. The period that follows in the southern Levant is marked by the development of territorial states throughout the region, circa 1000-800 BCE. These patrimonial kingdoms, including the United Kingdom of Israel and the divided kingdoms of northern Israel and Judah, coalesced varied peoples under central leadership and newly founded administrative and religious bureaucracies. Ancient DNA testing will give us a further refined understanding of the individuals who peopled the region of the southern Levant throughout its varied archaeological and historic periods and provide scientific data that will support, refute, or nuance our sociohistoric reconstruction of ancient group identities. These social identities may or may not map onto genetic data, but without sampling of ancient DNA we may never know. A database of ancient DNA will also allow for comparisons with modern DNA samples collected throughout the greater region and the Mediterranean littoral, giving a more robust understanding of the long historical trajectories of regional human genetics and the genetics of varied ancestral groups of today's Jewish populations and other cultural groups in the modern Middle East and Mediterranean.

  6. Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period

    DEFF Research Database (Denmark)

    Blunier, T; Brook, E J

    2001-01-01

    in Antarctica preceded the onset of Greenland warmings by 1500 to 3000 years. In general, Antarctic temperatures increased gradually while Greenland temperatures were decreasing or constant, and the termination of Antarctic warming was apparently coincident with the onset of rapid warming in Greenland...

  7. Deposition of Mn-Cu-Ni-enriched sediments during glacial period in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.

    Two siliceous sediment cores collected from the Central Indian Basin have been analysed for organic carbon, biogenic silica, Al, Mn, Ni and Cu content. The concentrations of Mn, Cu and Ni showed one order of magnitude variation (an enrichment by a...

  8. Palaeoceanography & Palaeoclimate during the penultimate Glacial-Interglacial transition in the Black Sea - Termination II

    Science.gov (United States)

    Wegwerth, Antje; Dellwig, Olaf; Kaiser, Jérôme; Bard, Edouard; Ménot, Guillemette; Nowaczyk, Norbert; Plessen, Birgit; Schnetger, Bernhard; Shumilovskikh, Lyudmila; Arz, Helge

    2013-04-01

    The epicontinental Black Sea is very sensitive to environmental changes thus forming an ideal archive of regional climate change and teleconnective responses to the coupled North Atlantic ocean-atmosphere system. Here we focus on the climatic and hydrological evolution of the SE Black Sea during the glacial-interglacial transition of Termination II to the Eemian (~134-122 ka BP) by using different geochemical and sedimentological proxies. Long-term cold conditions during the ending penultimate glacial are provided by TEX86 derived summer sea-surface temperatures (SST) of around 9°C and are thus considerable lower than present values of about 23°C. Coastal ice formation during extreme winters accounted for huge discharge of ice rafted debris (IRD) until 130.5 ka BP. Milder more humid conditions during this period are indicated for instance by elevated Cr/Al values typical for an ultramafic Pontic Mountain source (Piper and Calvert, 2011) thereby suggesting an increased sediment load mainly from the east-Anatolian rivers Kizilirmak and Yesilirmak. The abrupt disappearance of IRD along with increasing δ18O, Mg/Ca, and Sr/Ca of benthic ostracods (Candona spp.) resulted from slightly rising temperatures (SST 11°C) until 128.8 ka BP. Thereafter, SST rapidly increased within less than 500 years to about 25°C revealing a dramatic change from glacial to interglacial conditions. First analyses of U/Ca-ratios of ostracods show sharply increasing values not before ~128.3 ka BP, synchronous to the appearance of larval Mytilus galloprovincialis shells, due to the Mediterranean transgression into the Black Sea. The simultaneous increase of TOC and Mo/Al of the bulk sediment indicates the development of oxygen-deficient bottom waters and Eemian sapropel formation favoured by the establishment of a halocline shortly after the Mediterranean-Black Sea reconnection. About 500 years after the temperature maximum, the continental environment responded to the warming by elevated

  9. Modeling the Spreading of Glacial Melt Water from the Amundsen and Bellingshausen Seas

    Science.gov (United States)

    Nakayama, Y.; Timmermann, R.; Rodehacke, C. B.; Schröder, M.; Hellmer, H. H.

    2014-12-01

    The ice shelves and glaciers of the West Antarctic Ice Sheet (WAIS) are rapidly thinning, especially in the Amundsen Sea (AS) and Bellingshausen Sea (BS). The high basal melting of these small ice shelves is caused by relatively warm Circumpolar Deep Water (CDW) that, based on observations, mainly intrudes via two submarine glacial troughs located at the eastern and central AS continental shelf break. When CDW reaches the grounding line of the fringing glaciers, it melts the glaciers and forms buoyant melt water plumes. As the glacial melt becomes part of the AS shelf circulation, it may cause a freshening of the shelf water locally as well as remotely in the Ross Sea (RS). To test whether the observed freshening of the RS is a consequence of the enhanced basal melting of AS ice shelves, we use Finite-Element Sea-ice/ice-shelf/Ocean Model (FESOM) with a horizontal resolution of 2-10 km on the AS and BS continental shelves. The model is forced with 6-hourly atmospheric data from the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP-CFSR) for the period 1979-1988. The model results show bottom temperatures in the AS and BS close to observations, and basal melt rates of AS and BS ice shelves consistent with other observation-based estimates. Using several independent virtual passive tracers to identify pathways of the glacial melt, we find that the melt water from the ice shelves in the AS flows towards the Ross Ice Shelf front. After 10 years of simulation, about half of the melt water in the Ross Sea originates from the Getz Ice Shelf. Further, we investigate the sensitivity of the melt water transport into the RS associated with the strength of the basal melt water flux. When this flux is increased by 30%, the transport of glacial melt into the RS more than doubles, supporting the idea that the basal melting of AS and BS ice shelves is one of the main reasons for the freshening of the RS continental shelf.

  10. Simulating the last glacial-interglacial transition with a coupled atmosphere-ocean-ice sheet model

    Science.gov (United States)

    Mikolajewicz, Uwe; Ziemen, Florian

    2015-04-01

    One of the major challenges in climate modeling is the simulation of glacial-interglacial transitions. A few models of intermediate complexity have been successful in simulating the last termination. Complex atmosphere-ocean general circulation models have been shown to be able to yield realistic climate changes with prescribed ice sheets. Here we presents results from a first attempt to simulate a substantial part of the last glacial cycle with an AOGCM coupled interactively with a state-of-the-art ice sheet model. The ECHAM5/MPIOM AOGCM has been interactively coupled to the dynamical ice sheet model PISM. The latter is run for most of the northern hemisphere with a horizontal resolution of 20 km. An earlier version of this model ( Ziemen et al. 2014) has been applied to a steady state simulation of the last glacial maximum (LGM). The model was integrated from the late Glacial into the Holocene using insolation and greenhouse gas concentrations as transient forcing. Land sea mask and ocean topography are fixed at LGM conditions, river routing and surface elevation for the atmospheric model component are calculated interactively depending on the simulated ice sheets. To make these long simulations feasible, the atmosphere is accelerated by a factor of 10 relative to the other model components using a periodically-synchronous coupling technique. A mini-ensemble with different initial conditions has been run. In all simulation the northern hemispheric deglaciation starts between 18 and 17 kyr BP, consistent with the onset of global warming. The model produces Heinrich event like variability as part of its internal variability. These rapid ice discharge events have a strong impact on the North Atlantic meridional overturning circulation (NAMOC). During the peak deglaciation the NAMOC is collapsed (with a few short interruptions) for several thousand years, which is longer than the estimates from reconstructions. This seems to be an artifact due to keeping ocean

  11. Progress and challenges in deciphering the glacial chronology of the Alpine Lateglacial of the Eastern Alps

    Science.gov (United States)

    Reitner, Juergen

    2015-04-01

    For more than a hundred years efforts have been undertaken to decipher the Alpine Lateglacial (appr. 20 -12 ka), i.e., the period beginning with the withdrawal of the LGM glaciers from their tongue basins until the onset of the Holocene. Since the pioneering work of Penck & Brückner many modifications and improvements of the original subdivision into glacial stadials have been put forward. Especially the application of equilibrium line altitude depressions (ΔELAs) resulted in the definition of new glacial stadials since the 1960's. In addition, previously defined stadials were re-defined using morphological criteria as well as ΔELAs but without any reference to the original type localities. Finally, modern geochronology, especially surface exposure dating with cosmogenic nuclides, helped to establish a chronological framework and enabled correlation with high-resolution marine and ice-core records and elaborated paleoclimatic consideration. However, the results of comprehensive geological mapping in combination with surface exposure dating and radiocarbon dating indicate a bias in the commonly used subdivision of the Alpine Lateglacial. This seems to be, on the one hand, the result of a rigorous application of differences in ΔELA for chronological correlations, which led to the underestimation of regional differences within one climatic phase. On the other hand, only one type-locality has been dated so far. Moreover, as no "type-valley" exists where all moraines of the proposed glacial stadials are evident, we run into the danger of using a sub-division of the Alpine Lateglacial, which contains unjustified chronostratigraphic artefacts. In other words, based on recent work an overclassification may have been established. Beyond the well-known Younger Dryas glaciation only a floating or at least poorly referenced stratigraphy prior to the Bølling/Allerød interstadial (> 14.7 ka) is in use. Examples will be presented which show the current problems and how

  12. Period Pain

    Science.gov (United States)

    ... You may also have other symptoms, such as lower back pain, nausea, diarrhea, and headaches. Period pain is not ... Taking a hot bath Doing relaxation techniques, including yoga and meditation You might also try taking over- ...

  13. Irregular Periods

    Science.gov (United States)

    ... blood become too low or too high. Some women have irregular periods because their bodies produce too much androgen, which is a hormone that causes increased muscle mass, facial hair, and deepening of the voice in males and ...

  14. Marine Isotope Stages (MIS) 96-101: Glacial induced closure of the Panamanian Gateway

    Science.gov (United States)

    Groeneveld, Jeroen; Debey, Henry; Hathorne, Ed C.; Steinke, Stephan

    2010-05-01

    We present combined Mg/Ca and δ18O measurements from ODP Site 1241 from the east Pacific and ODP Site 999 from the Caribbean. The studied time interval covers the first major glacial-interglacial cycles (MIS96-101) after intensification of Northern Hemisphere Glaciation. Analyses were performed on the planktic foraminifers Neogloboquadrina dutertrei and Globigerinoides sacculifer, representing water mass properties in the thermocline and the mixed layer respectively. Data resolution is aimed to be able to resolve millennial scale variations to constrain the changes in water mass conditions during MIS96-101. Aim of the study is to test the theory that the Panamanian Gateway temporarily closed during glacial MIS 96, 98, and 100 due to a drop in sea level of 50-80 m. This was first suggested in Groeneveld et al., (in prep.) and might have provided the necessary conditions to allow the Great American Biotic Interchange, the large scale migration of mammals from South to North America and vice versa. As this exchange would have required more arid conditions in Central America to allow the fauna, which was mainly adapted to a savannah-like environment, to cross, a glacial period would have provided the right conditions. Reconstruction of sea water temperatures can indicate if and when the gateway closed. With an open Panamanian Gateway relatively cold water flowed from the Pacific into the Caribbean. With the onset of glacial conditions sea surface temperatures (SST) expectedly would show a decrease in the east Pacific (Site 1241). But, SSTs in the Caribbean (Site 999) are expected to rise as no longer relatively cold Pacific water is entering the Caribbean, but rather the warmer waters from the Western Atlantic Warm Pool advanced from the north to the core location. Indeed, reconstructed SSTs from G. sacculifer show a decrease of 2.5° C at Site 1241 and an increase of 3° C at Site 999 suggesting that the Panamanian Gateway truly was closed during the glacial stage

  15. Glacial cycles and the growth and destruction of Alaska volcanoes

    Science.gov (United States)

    Coombs, M. L.; Calvert, A. T.; Bacon, C. R.

    2014-12-01

    Glaciers have affected profoundly the growth, collapse, preservation, and possibly, eruptive behavior of Quaternary stratovolcanoes in Alaska. Holocene alpine glaciers have acted as effective agents of erosion on volcanoes north of ~55 °N and especially north of 60 °N. Cook Inlet volcanoes are particularly vulnerable as they sit atop rugged intrusive basement as high as 3000 m asl. Holocene glaciers have swept away or covered most of the deposits and dome lavas of frequently active Redoubt (60.5 °N); carved through the flanks of Spurr's active vent, Crater Peak (61.3 °N); and all but obscured the edifice of Hayes (61.6 °N), whose Holocene eruptive history is known almost exclusively though far-traveled tephra and flowage deposits. Relationships between Pleistocene eruptive histories, determined by high-precision Ar-Ar dating of lava flows, and marine oxygen isotope stages (MIS) 2-8 (Bassinot et al., 1994, EPSL, v. 126, p. 91­-108) vary with a volcano's latitude, size, and elevation. At Spurr, 26 ages cluster in interglacial periods. At Redoubt, 28 ages show a more continual eruptive pattern from the end of MIS 8 to the present, with a slight apparent increase in output following MIS 6, and almost no preservation before 220 ka. Veniaminof (56.2 °N) and Emmons (55.5°N), large, broad volcanoes with bases near sea level, had voluminous eruptive episodes during the profound deglaciations after MIS 8 and MIS 6. At Akutan (54.1 °N), many late Pleistocene lavas show evidence for ice contact; ongoing dating will be able to pinpoint ice thicknesses. Furthest south and west, away from thick Pleistocene ice on the Alaska Peninsula and mainland, the Tanaga volcanic cluster (51.9 °N) has a relatively continuous eruptive record for the last 200 k.y. that shows no clear-cut correlation with glacial cycles, except a possible hiatus during MIS 6. Finally, significant edifice collapse features have been temporally linked with deglaciations. A ~10-km3 debris

  16. Late-glacial elevated dust deposition linked to westerly wind shifts in southern South America

    Science.gov (United States)

    Vanneste, Heleen; de Vleeschouwer, François; Martínez-Cortizas, Antonio; von Scheffer, Clemens; Piotrowska, Natalia; Coronato, Andrea; Le Roux, Gaël

    2015-07-01

    Atmospheric dust loadings play a crucial role in the global climate system. Southern South America is a key dust source, however, dust deposition rates remain poorly quantified since the last glacial termination (~17 kyr ago), an important timeframe to anticipate future climate changes. Here we use isotope and element geochemistry in a peat archive from Tierra del Fuego, to reconstruct atmospheric dust fluxes and associated environmental and westerly wind changes for the past 16.2 kyr. Dust depositions were elevated during the Antarctic Cold Reversal (ACR) and second half of the Younger Dryas (YD) stadial, originating from the glacial Beagle Channel valley. This increase was most probably associated with a strengthening of the westerlies during both periods as dust source areas were already available before the onset of the dust peaks and remained present throughout. Congruent with glacier advances across Patagonia, this dust record indicates an overall strengthening of the wind belt during the ACR. On the other hand, we argue that the YD dust peak is linked to strong and poleward shifted westerlies. The close interplay between dust fluxes and climatic changes demonstrates that atmospheric circulation was essential in generating and sustaining present-day interglacial conditions.

  17. Simulations of the last interglacial and the subsequent glacial inception with the Planet Simulator

    Directory of Open Access Journals (Sweden)

    M. Donat

    2006-12-01

    Full Text Available The Planet Simulator was used to perform equilibrium simulations of the Eemian interglacial at 125 kyBP and the glacial inception at 115 kyBP. Additionally, an accelerated transient simulation of that interval was performed. During this period the changes of Earth's orbital parameters led to a reduction of summer insolation in the northern latitudes. The model has been run in different configurations in order to evaluate the influence of the individual sub-models. The strongest reaction on the insolation change was observed when the atmosphere was coupled with all available sub-systems: a mixed-layer ocean and a sea-ice model as well as a vegetation model. In the simulations representing the interglacial, the near-surface temperature in northern latitudes is higher compared to the preindustrial reference run and almost no perennial snow cover occurs. In the run for the glacial inception, wide areas in mid and high northern latitudes show negative temperature anomalies and wide areas are covered by snow or ice. The transient simulation shows that snow volume starts to increase after summer insolation has fallen below a critical value. The main reason for the beginning glaciation is the locally reduced (summer temperature as a consequence of reduced summer insolation. Therefore, a larger fraction of precipitation falls as snow and less snow can melt. That mechanism is amplified by the snow-albedo-feedback.

  18. Debris flow sensitivity to glacial-interglacial climate change - supply vs transport

    Science.gov (United States)

    D'Arcy, Mitch; Roda Boluda, Duna C.; Whittaker, Alexander C.

    2016-04-01

    Numerical models suggest that small mountain catchment-alluvial fan systems might be sensitive to climate changes over glacial-interglacial cycles, and record these palaeoclimate signals in the sedimentology of their deposits. However, these models are still largely untested, and the propagation of climate signals through simple sediment routing systems remains contentious. Here, we present detailed sedimentological records from 8 debris flow fan systems in Owens Valley, California, that capture the past ~ 120 ka of deposition. We identify a strong and sustained relationship between deposit grain size and palaeoclimate records over a full glacial-interglacial cycle, with significantly coarser-grained deposits found in warm and dry periods. Our data show that these systems are highly sensitive to climate with a rapid response timescale of debris flows are triggered by surface runoff during intense storms, we interpret that enhanced runoff rates in warm and stormy conditions are responsible for entraining larger clasts during debris flow initiation. This implies that debris flow fans might record signals of past storm intensity. Our study utilises field sedimentology and focuses on short transport distances (~ 10 km) and climate changes over ~ 1-100 ka timespans, but could additionally have important implications for how eroding landscapes might respond to future warming scenarios. We address the importance of extreme events (such as storms and debris flows) for determining how sensitive landscapes are to climate variability.

  19. Rapid glacial retreat on the Kamchatka Peninsula during the early 21st century

    Science.gov (United States)

    Lynch, Colleen M.; Barr, Iestyn D.; Mullan, Donal; Ruffell, Alastair

    2016-08-01

    Monitoring glacier fluctuations provides insights into changing glacial environments and recent climate change. The availability of satellite imagery offers the opportunity to view these changes for remote and inaccessible regions. Gaining an understanding of the ongoing changes in such regions is vital if a complete picture of glacial fluctuations globally is to be established. Here, satellite imagery (Landsat 7, 8 and ASTER) is used to conduct a multi-annual remote sensing survey of glacier fluctuations on the Kamchatka Peninsula (eastern Russia) over the 2000-2014 period. Glacier margins were digitised manually and reveal that, in 2000, the peninsula was occupied by 673 glaciers, with a total glacier surface area of 775.7 ± 27.9 km2. By 2014, the number of glaciers had increased to 738 (reflecting the fragmentation of larger glaciers), but their surface area had decreased to 592.9 ± 20.4 km2. This represents a ˜ 24 % decline in total glacier surface area between 2000 and 2014 and a notable acceleration in the rate of area loss since the late 20th century. Analysis of possible controls indicates that these glacier fluctuations were likely governed by variations in climate (particularly rising summer temperatures), though the response of individual glaciers was modulated by other (non-climatic) factors, principally glacier size, local shading and debris cover.

  20. One-to-one coupling of glacial climate variability in Greenland and Antarctica

    Science.gov (United States)

    Epica Community Members; Barbante, C.; Barnola, J.-M.; Becagli, S.; Beer, J.; Bigler, M.; Boutron, C.; Blunier, T.; Castellano, E.; Cattani, O.; Chappellaz, J.; Dahl-Jensen, D.; Debret, M.; Delmonte, B.; Dick, D.; Falourd, S.; Faria, S.; Federer, U.; Fischer, H.; Freitag, J.; Frenzel, A.; Fritzsche, D.; Fundel, F.; Gabrielli, P.; Gaspari, V.; Gersonde, R.; Graf, W.; Grigoriev, D.; Hamann, I.; Hansson, M.; Hoffmann, G.; Hutterli, M. A.; Huybrechts, P.; Isaksson, E.; Johnsen, S.; Jouzel, J.; Kaczmarska, M.; Karlin, T.; Kaufmann, P.; Kipfstuhl, S.; Kohno, M.; Lambert, F.; Lambrecht, Anja; Lambrecht, Astrid; Landais, A.; Lawer, G.; Leuenberger, M.; Littot, G.; Loulergue, L.; Lüthi, D.; Maggi, V.; Marino, F.; Masson-Delmotte, V.; Meyer, H.; Miller, H.; Mulvaney, R.; Narcisi, B.; Oerlemans, J.; Oerter, H.; Parrenin, F.; Petit, J.-R.; Raisbeck, G.; Raynaud, D.; Röthlisberger, R.; Ruth, U.; Rybak, O.; Severi, M.; Schmitt, J.; Schwander, J.; Siegenthaler, U.; Siggaard-Andersen, M.-L.; Spahni, R.; Steffensen, J. P.; Stenni, B.; Stocker, T. F.; Tison, J.-L.; Traversi, R.; Udisti, R.; Valero-Delgado, F.; van den Broeke, M. R.; van de Wal, R. S. W.; Wagenbach, D.; Wegner, A.; Weiler, K.; Wilhelms, F.; Winther, J.-G.; Wolff, E.

    2006-11-01

    Precise knowledge of the phase relationship between climate changes in the two hemispheres is a key for understanding the Earth's climate dynamics. For the last glacial period, ice core studies have revealed strong coupling of the largest millennial-scale warm events in Antarctica with the longest Dansgaard-Oeschger events in Greenland through the Atlantic meridional overturning circulation. It has been unclear, however, whether the shorter Dansgaard-Oeschger events have counterparts in the shorter and less prominent Antarctic temperature variations, and whether these events are linked by the same mechanism. Here we present a glacial climate record derived from an ice core from Dronning Maud Land, Antarctica, which represents South Atlantic climate at a resolution comparable with the Greenland ice core records. After methane synchronization with an ice core from North Greenland, the oxygen isotope record from the Dronning Maud Land ice core shows a one-to-one coupling between all Antarctic warm events and Greenland Dansgaard-Oeschger events by the bipolar seesaw6. The amplitude of the Antarctic warm events is found to be linearly dependent on the duration of the concurrent stadial in the North, suggesting that they all result from a similar reduction in the meridional overturning circulation.

  1. A multi-proxy palaeoecological and palaeoclimatic record within full glacial lacustrine deposits, western Tennessee, USA

    Science.gov (United States)

    Grimley, D.A.; Daniel, L.; Kaplan, S.W.; Yansa, C.H.; Curry, B. Brandon; Oches, E.A.

    2009-01-01

    The Fulton Section, along the Mississippi River in western Tennessee, USA, is a 1km continuous exposure (~20m vertically) of Quaternary fluvial and lacustrine deposits, inset within Eocene sediments and buried by thick loess. Fossiliferous slackwater lake sediments record maximum aggradation during the last two major glaciations, with deposition between ca. 190-140 ka and 24-1814C ka BP, based on amino acid and radiocarbon chronology, respectively. During the onset of full glacial conditions (ca. 24-22 14C ka BP), a relatively permanent shallow lake environment is indicated by ostracods, aquatic molluscs, and both pollen and macrofossils of aquatic plants. By 21.8 14C ka BP, increasing emergent plants, amphibious gastropods (Pomatiopsis) and heavier ??18O compositions suggest marsh-like conditions in a periodically drying lake. The surrounding uplands consisted of Picea-Pinus woodlands mixed with cool-temperate hardwoods (e.g. Quercus, Populus, Carya), grasses and herbs. More open conditions ensued ca. 20 14C ka BP, with loess and slopewash gradually infilling the former lake by 18 14C ka BP. Modern analogue analyses of ostracods and palaeontological evidence imply a full glacial climate similar to today's mixed-boreal zone in central Minnesota, USA, about 98C cooler in mean annual temperature than present-day western Tennessee. Copyright ?? 2009 John Wiley & Sons, Ltd.

  2. Reconstruction of paleocoastlines for the northwestern South China Sea since the Last Glacial Maximum

    Institute of Scientific and Technical Information of China (English)

    YAO YanTao; HARFF Jan; MEYER Michael; ZHAN WenHuan

    2009-01-01

    The range of relative sea level rise in the northwestern South China Sea since the Last Glacial Maximum was over 100 m. As a result, lowland regions including the Northeast Vietnam coast, Beibu Gulf, and South China coast experienced an evolution from land to sea. Based on the principle of recon structing paleogeography and using recent digital elevation model, relative sea level curves, and sediment accumulation data, this paper presents a series of paleogeographic scenarios back to 20 cal. ka BP for the northwestern South China Sea. The scenarios demonstrate the entire process of coastline changes for the area of interest. During the late glacial period from 20 to 15 cal. ka BP, coastline slowly retreated, causing a land loss of only 1 ×104 km2, and thus the land-sea distribution remained nearly unchanged. Later in 15--10 cal. ka BP coastline rapidly retreated and area of land loss was up to 24×104 km2, causing lowlands around Northeast Vietnam and South China soon to be underwater. Coastline retreat continued quite rapidly during the early Holocene. From 10 to 6 cal. ka BP land area had decreased by 9×104 km2, and during that process the Qiongzhou Strait completely opened up. Since the mid Holocene, main controls on coastline change are from vertical crustal movements and sedimentation. Transgression was surpassed by regression, resulting in a land accretion of about 10×104 km2.

  3. Reconstruction of paleocoastlines for the northwestern South China Sea since the Last Glacial Maximum

    Institute of Scientific and Technical Information of China (English)

    HARFF; Jan; MEYER; Michael

    2009-01-01

    The range of relative sea level rise in the northwestern South China Sea since the Last Glacial Maximum was over 100 m. As a result, lowland regions including the Northeast Vietnam coast, Beibu Gulf, and South China coast experienced an evolution from land to sea. Based on the principle of reconstructing paleogeography and using recent digital elevation model, relative sea level curves, and sediment accumulation data, this paper presents a series of paleogeographic scenarios back to 20 cal. ka BP for the northwestern South China Sea. The scenarios demonstrate the entire process of coastline changes for the area of interest. During the late glacial period from 20 to 15 cal. ka BP, coastline slowly retreated, causing a land loss of only 1×104 km2, and thus the land-sea distribution remained nearly unchanged. Later in 15-10 cal. ka BP coastline rapidly retreated and area of land loss was up to 24×104 km2, causing lowlands around Northeast Vietnam and South China soon to be underwater. Coastline retreat continued quite rapidly during the early Holocene. From 10 to 6 cal. ka BP land area had decreased by 9×104 km2, and during that process the Qiongzhou Strait completely opened up. Since the mid Holocene, main controls on coastline change are from vertical crustal movements and sedimentation. Transgression was surpassed by regression, resulting in a land accretion of about 10×104 km2.

  4. Late-glacial elevated dust deposition linked to westerly wind shifts in southern South America.

    Science.gov (United States)

    Vanneste, Heleen; De Vleeschouwer, François; Martínez-Cortizas, Antonio; von Scheffer, Clemens; Piotrowska, Natalia; Coronato, Andrea; Le Roux, Gaël

    2015-01-01

    Atmospheric dust loadings play a crucial role in the global climate system. Southern South America is a key dust source, however, dust deposition rates remain poorly quantified since the last glacial termination (~17 kyr ago), an important timeframe to anticipate future climate changes. Here we use isotope and element geochemistry in a peat archive from Tierra del Fuego, to reconstruct atmospheric dust fluxes and associated environmental and westerly wind changes for the past 16.2 kyr. Dust depositions were elevated during the Antarctic Cold Reversal (ACR) and second half of the Younger Dryas (YD) stadial, originating from the glacial Beagle Channel valley. This increase was most probably associated with a strengthening of the westerlies during both periods as dust source areas were already available before the onset of the dust peaks and remained present throughout. Congruent with glacier advances across Patagonia, this dust record indicates an overall strengthening of the wind belt during the ACR. On the other hand, we argue that the YD dust peak is linked to strong and poleward shifted westerlies. The close interplay between dust fluxes and climatic changes demonstrates that atmospheric circulation was essential in generating and sustaining present-day interglacial conditions.

  5. Early and late Holocene glacial fluctuations and tephrostratigraphy, Cabin Lake, Alaska

    Science.gov (United States)

    Zander, Paul D.; Kaufman, Darrell S.; Kuehn, Stephen C.; Wallace, Kristi L.; Anderson, R. Scott

    2013-01-01

    Marked changes in sediment types deposited in Cabin Lake, near Cordova, Alaska, represent environmental shifts during the early and late Holocene, including fluctuations in the terminal position of Sheridan Glacier. Cabin Lake is situated to receive meltwater during periods when the outwash plain of the advancing Sheridan Glacier had aggraded. A brief early Holocene advance from 11.2 to 11.0 cal ka is represented by glacial rock flour near the base of the sediment core. Non-glacial lake conditions were restored for about 1000 years before the water level in Cabin Lake lowered and the core site became a fen. The fen indicates drier-than-present conditions leading up to the Holocene thermal maximum. An unconformity spanning 5400 years during the mid-Holocene is overlain by peat until 1110 CE when meltwater from Sheridan Glacier returned to the basin. Three intervals of an advanced Sheridan Glacier are recorded in the Cabin Lake sediments during the late Holocene: 1110–1180, 1260–1540 and 1610–1780 CE. The sedimentary sequence also contains the first five reported tephra deposits from the Copper River delta region, and their geochemical signatures suggest that the sources are the Cook Inlet volcanoes Redoubt, Augustine and Crater Peak, and possibly Mt Churchill in the Wrangell Volcanic field.

  6. Evidence of late glacial paleoseismicity from submarine landslide deposits within Lac Dasserat, northwestern Quebec, Canada

    Science.gov (United States)

    Brooks, Gregory R.

    2016-09-01

    An integrated seismo- and chronostratigraphic investigation at Lac Dasserat, northwestern Quebec, identified 74 separate failures within eight event horizons. Horizons E and B, and H and G have strong or moderately-strong multi-landslide signatures, respectively, composed of 11-23 failures, while horizons F, D, C, and A have minor landslide signatures consisting of a single or pair of deposit(s). Cores collected at six sites recovered glacial Lake Ojibway varve deposits that are interbedded with the event horizons. The correlation of the varves to the regional Timiskaming varve series allowed varve ages or ranges of varve ages to be determined for the event horizons. Horizons H, G, E, and B are interpreted to be evidence of paleoearthquakes with differing levels of interpretative confidence, based on the relative strength of the multi-landslide signatures, the correlation to other disturbed deposits of similar age in the region, and the lack or possibility of alternative aseismic mechanisms. The four interpreted paleoearthquakes occurred between 9770 ± 200 and 8470 ± 200 cal yr BP, when glacial Lake Ojibway was impounded behind the Laurentide Ice Sheet during deglaciation. They probably represent an elevated period of seismicity at deglaciation that was driven by crustal unloading.

  7. Population Dynamics Following the Last Glacial Maximum in Two Sympatric Lizards in Northern China

    Institute of Scientific and Technical Information of China (English)

    Yanfu QU; Qun ZHAO; Hongliang LU; Xiang JI

    2014-01-01

    Phylogeographic studies ofEremias lizards (Lacertidae) in East Asia have been limited, and the impact of major climatic events on their population dynamics remains poorly known. This study aimed to investigate population histories and refugia during the Last Glacial Maximum of two sympatricEremias lizards (E. argus andE. brenchleyi) inhabiting northern China. We sequenced partial mitochondrial DNA from theND4 gene for 128 individuals ofE. argus from nine localities, and 46 individuals ofE. brenchleyi from ifve localities. Forty-fourND4 haplotypes were determined fromE. argus samples, and 33 fromE. brenchleyi samples. Population expansion events began about 0.0044 Ma inE. argus, and 0.031 Ma inE. brenchleyi. The demographic history ofE. brenchleyi indicates a long-lasting population decline since the most recent common ancestor, while that ofE. argusindicates a continuous population growth. Among-population structure was signiifcant in both species, and there were multiple refugia across their range. Intermittent gene flow occurred among expanded populations across multiple refugia during warmer phases of the glacial period, and this may explain why the effective population size has remained relatively stable inE. brenchleyi and grown inE. argus.

  8. Climate change and evolving human diversity in Europe during the last glacial.

    Science.gov (United States)

    Gamble, Clive; Davies, William; Pettitt, Paul; Richards, Martin

    2004-02-29

    A link between climate change and human evolution during the Pleistocene has often been assumed but rarely tested. At the macro-evolutionary level Foley showed for hominids that extinction, rather than speciation, correlates with environmental change as recorded in the deep sea record. Our aim is to examine this finding at a smaller scale and with high-resolution environmental and archaeological archives. Our interest is in changing patterns of human dispersal under shifting Pleistocene climates during the last glacial period in Europe. Selecting this time frame and region allows us to observe how two hominid taxa, Neanderthals and Crô-Magnons, adapted to climatic conditions during oxygen isotope stage 3. These taxa are representative of two hominid adaptive radiations, termed terrestrial and aquatic, which exhibited different habitat preferences but similar tolerances to climatic factors. Their response to changing ecological conditions was predicated upon their ability to extend their societies in space and time. We examine this difference further using a database of all available radiocarbon determinations from western Europe in the late glacial. These data act as proxies for population history, and in particular the expansion and contraction of regional populations as climate changed rapidly. Independent assessment of these processes is obtained from the genetic history of Europeans. The results indicate that climate affects population contraction rather than expansion. We discuss the consequences for genetic and cultural diversity which led to the legacy of the Ice Age: a single hominid species, globally distributed.

  9. Erosion of the Laurentide region of North America by glacial and glaciofluvial processes

    Science.gov (United States)

    Bell, M.; Laine, E.P.

    1985-01-01

    Collection of seismic reflection data from continental margins and ocean basins surrounding North America makes it possible to estimate the amount of material eroded from the area formerly covered by Laurentide ice sheets since major glaciation began in North America. A minimum estimate is made of 1.62 ?? 106 km3, or an average 120 m of rock physically eroded from the Laurentide region. This figure is an order of magnitude higher than earlier estimates based on the volume of glacial drift, Cenozoic marine sediments, and modern sediment loads of rivers. Most of the sediment produced during Laurentide glaciation has already been transported to the oceans. The importance of continental glaciation as a geomorphic agency in North America may have to be reevaluated. Evidence from sedimentation rates in ocean basins surrounding Greenland and Antarctica suggests that sediment production, sediment transport, and possibly denudation by permanent ice caps may be substantially lower than by periodic ice caps, such as the Laurentide. Low rates of sediment survival from the time of the Permo-Carboniferous and Precambrian glaciations suggest that predominance of marine deposition during some glacial epochs results in shorter lived sediment because of preferential tectonism and cycling of oceanic crust versus continental crust. ?? 1985.

  10. QUERIES ABOUT THE GLACIAL POTHOLES OF MOUNTAIN LAOSHAN,CHINA%崂山冰臼之质疑

    Institute of Scientific and Technical Information of China (English)

    王为; 周尚哲; 李炳元; 解波; 冯小珍

    2011-01-01

    In July of 2010, the authors made a field investigation of Mountain Laoshan, which is composed of Mesozoic granite with its highest peak rising 1133 meters above sea level and is located on the shore of the Yellow Sea, China. The granite landforms of Mountain Laoshan have recently been considered as those created by the action of Quaternary glaciers in East China and well preserved. The critical evidence of the existence of the ancient Laoshan glaciers is the pits of various size apertures found on the rock surfaces of Mountain Laoshan. The pits from high altitude to low altitude of the mountain are interpreted as glacial potholes. In the investigation the features of the so-called glacial potholes were examined and the morphological parameters of them were measured as well. In this paper,a comparison of the differences in morphological features is made between the pits found in Mountain Laoshan and the true glacier potholes in other places of the world, showing that the so-called glacial potholes of Mountain Laoshan do not have the features created by subglacial fluvial erosion but have all the features a weathering pit should have, such as flat bottom, spill way, over hanging sides and so on. This paper enumerates a series of self-contradictory statements about the glacier pothole formation in Mountain Laoshan and other places of China made by the supporters of Quaternary glaciers in East China. This paper also replys to questions about weathering pit formation which are raised by the same persons and points out that the main cause for mistaking weathering pits for glacial potholes is a lack of geomorphologic knowledge to distinguish weathering and erosion processes, which includes the stream erosion and subglacial fluvial erosion. The conclusion is made that the so-called glacial potholes in Mountain Laoshan are nothing but weathering pits as generally found in other granite areas around the world and then the present landforms of Mountain Laoshan are not

  11. Luminescence dating of ancient Darhad basin, Mongolia

    Science.gov (United States)

    Cheul Kim, Jin; Yi, Sangheon; Lim, Jaesoo; Kim, Ju-Yong

    2016-04-01

    Darhad basin is located in the northern Mongolia, in the western end of the Baikal Rift Zone. In contrast to the neighboring Lake Hovsgol, Mongolia's largest and deepest lake, the Darhad is a drained lake basin. It is ~100 km long (north-south), 20-40 km wide and covered by sediments which locally exceed 500 m thickness (Zorin et al., 1989). Darhad basin is characterized by alternating episodes of expansion and desiccation that are closely related with the Pleistocene damming events. Previous studies of the Darhad Basin suggest that the last paleolake was dammed by a large glacier or the sediments (Selivanov, 1967, 1968; Krivonogov et al., 2005; Gillespie et al., 2008). Especially, recent expansion of the paleolake might be caused by the two glacial maxima during MIS 4 and 2. However, glacier-dammed lakes might be short-lived, dried up and permafrost occurred in the drained basin during the Holocene period. The uppermost paleolake sediments (13.2 m depth) are exposed following the curvature of the meandering river (called "Hodon outcrop"). It is considered the most likely site for the youngest paleolake sediments because it is distributed in the northern middle part of the paleolake. Krivonogov et al. 2012 described the Hodon outcrop with the sedimentological and chronological data. Age dating of 16 samples (11 mollusk shells, 5 wood fragments) indicated that Hodon outcrop sediments were deposited between 10.1±7 and 4.9±5 ka. However, the ages obtained on shells much older dates than the matched wood samples because of ingestion of old carbon by mollusks. The age difference between shells and wood fragments is a minimum of 1.73 ka and a maximum of 3.41 ka (average 2.5 ka). In this case, 14C ages from shells should be corrected with appropriate correction factor. However, the old carbon effects could vary temperally and spatially in the Darhad paleolake. The limited number of the 14C ages from wood fragments result in a simple linear trend in the depth-age curve

  12. 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

    The analysis of the slope-area relationship in bedrock streams is a common way for discriminating the channel from the hillslope domain and associated landscape processes. Spatial variations of these domains are important indicators of landscape change. In fluvial catchments, this relationship is a function of contributing drainage area, channel slope and the threshold drainage area for fluvial erosion. The resulting pattern is related to climate, tectonic and underlying bedrock. These factors may become secondary in catchments affected by glacial erosion, as it is the case in many mid- to high-latitude mountain belts. The perturbation (i.e. the destruction) of an initial steady state fluvial bedrock morphology (where uplift is balanced by surface lowering rates) will tend to become successively larger if the repeated action of glacial processes exceeds the potential of fluvial readjustment during deglaciated periods. Topographic change is associated with a decrease and fragmentation of the channel network and an extension of the hillslope domain. In case of glacially conditioned catchments discrimination of the two domains remains problematic and a discrimination inconsistent. A definition is therefore highly needed considering that (i) a spatial shift in the domains affect the process and rate of erosion and (ii) topographic classifications of alpine catchments often base on channel and hillslope parameters (i.e.channel or hillslope relief). Here we propose a novel numerical approach to topographically define channel heads from digital topography in glacially conditioned mountain range catchments in order to discriminate the channel from the hillslope domain. We analyzed the topography of the southern European Central Alps, a region which (i) has been glaciated multiple times during the Quaternary, shows (ii) little lithological variations, is (iii) home of very low erodible rocks and is (iv) known as a region were tectonic processes have largely ceased. The

  13. Paleomonsoonal Precipitation and Hydroclimate Variability from Glacial to Interglacial Climates in the Southwest: The Stoneman Lake, Arizona Record

    Science.gov (United States)

    Garcia, D.; Fawcett, P. J.; Anderson, R. S.; Sharp, Z. D.

    2015-12-01

    Oxygen isotope values from diatom silica have been used to determine past hydrological conditions in a variety of settings including differentiating summer monsoonal paleoprecipitation from winter frontal paleoprecipitation in the American southwest. Lacustrine cores from the Valles Caldera, New Mexico, show a distinct change in silica oxygen isotope values from glacial to interglacial as a switch from a purely winter frontal precipitation during the glacial to a mix of winter frontal and summer monsoonal precipitation during the interglacial. A relatively large (ca. 20‰) and rapid increase in δ18O following the glacial termination implies an abrupt onset of the North American monsoon. We plan to elaborate on this research to see if this is true elsewhere in the southwest. Two lacustrine sediment cores (70 m deep and 30 m deep respectively) were recovered from Stoneman Lake, northern Arizona in October of 2014. With these cores we plan to determine regional hydroclimate variability between the Pleistocene-Holocene glacial transition ca. 14 ka. Oxygen isotope analysis from diatom silica will allow us to determine past sources of precipitation to the basin (Gulf of Mexico vs North Pacific), and paleoprecipitation variability. In conjunction with other proxies, we can determine if the onset of paleomonsoonal precipitation in central Arizona occurs immediately after the glacial termination as in NM, or if there is some component of monsoonal precipitation during the late glacial period. Diatom sampling was performed at approximately every 50 cm. To purify the diatoms, the samples are chemically and physically separated. The step wise fluorination and laser ablation technique are then applied to remove water & hydroxyl groups and to extract O2 & SiF4 respectively.If results from the Stoneman Lake core are similar to that of the Valles Caldera core, we should expect to see a nearly 20‰ increase in δ18Olake water. This would suggest a: 1) collapse of the summer

  14. Miocene development of alpine glacial relief in the Patagonian Andes, as revealed by low-temperature thermochronometry

    Science.gov (United States)

    Christeleit, Elizabeth C.; Brandon, Mark T.; Shuster, David L.

    2017-02-01

    Apatite thermochronometry and synthetic maps of ages and rates for thermochronometric data are used to estimate the timing of incision of valley relief in the Andes. Central Patagonia offers a unique location to study the feedbacks between long-term climate, topography, and erosion due to the high relief and well-resolved mid-latitude glacial history. New apatite (U-Th)/He ages from two vertical transects and two 4He/3He release spectra in the fjord network around 47°S reveal fast cooling (15-30 °C/Ma) from ∼10 to 5 Ma. Samples currently at the surface cooled below ∼35 °C by ∼5 Ma, indicating slow cooling and little erosion in those regions since 5 Ma. We show that these very low-temperature thermochronometric data are useful indicators of changes in topography, and insensitive to deep thermal processes, such as migration of the Chile triple junction. Map-based predictions of the thermochronometric signatures of disparate topographic scenarios show the distribution of sample data necessary to resolve the timing of relief change. Comparisons to predicted cooling ages and rates indicate that our new apatite He data are most consistent with a pulse of early glacial incision, with much of the observed valley relief in Patagonia carved between 10 and 5 Ma. Early onset of glaciation in Patagonia is supported by glacial till with bracketing ages of 7.4 and 5 Ma. We therefore conclude that the observed thermochronometric signal of fast cooling from 10 to 5 Ma is likely due to an increase in valley relief coinciding with these early glaciations in the Andes. In other glaciated areas at lower latitudes, studies have found a dramatic increase in valley relief at ∼1 Ma. This timing has generated the idea that incision of glacial valleys may be related to the mid-Pleistocene transition, when the global glacial cycle changed from 40 to 100 ka periods. Our results from a higher latitude indicate an alternative, that glacial valleys incised rapidly after the onset of

  15. The impact of changing glacial coverage on yields of freshwater and nutrients from coastal watersheds with in southeastern Alaska

    Science.gov (United States)

    Hood, E.; Scott, D.

    2007-12-01

    Glaciers in southeastern Alaska are particularly sensitive to climate change because of their low elevation and proximity to the coast. Currently, glaciers in this region are experiencing high rates of ice loss resulting in rapid thinning and retreat. We are examining how changing glacial coverage is altering fluxes of freshwater and nutrients from coastal watersheds in southeastern Alaska. Our study includes three adjacent watersheds that range in area from 37 km2 to 230 km2 and span a range of watershed glacier coverage from 0% to 55%. Physical and hydrochemical parameters were sampled weekly to bi-monthly for the period May 2006-April 2007 in the three watersheds. Physical measurements included temperature, suspended sediment and conductivity; and hydrochemical parameters included total and inorganic nitrogen, dissolved organic carbon, sulfate, and orthophosphate. During the glacier melt season, glacial coverage within a watershed exerted a strong influence on physiochemical properties. Streamwater temperature and conductivity, as well as nutrient concentrations, were negatively correlated with glacier coverage, while suspended sediment loads were positively correlated with glacial coverage. Changing glacial coverage had a strong impact on watershed yields of carbon, nitrogen, and phosphorus. Watershed yields of dissolved organic carbon (DOC) ranged from 4246 to 7646 kg km-2 yr- 1 and were strongly negatively correlated with percent glacier coverage. Watershed yields of dissolved inorganic nitrogen ranged from 180 to 498 kg km-2 yr-1 and were highest in the watershed with intermediate glacier coverage that has a high proportion of transitional nitrogen fixing plant species. Watershed yields of orthophosphate ranged from 19 to 46 kg km-2 yr-1 and were strongly positively correlated with glacier coverage. Our findings suggest that the magnitude and timing of freshwater and nutrient fluxes from coastal watersheds to receiving marine ecosystems will be altered

  16. A first 10Be cosmogenic glacial chronology from the High Atlas, Morocco, during the last glacial cycle.

    Science.gov (United States)

    Fink, David; Hughes, Philip; Fenton, Cassie

    2014-05-01

    Glacial geomorphological mapping, 10Be cosmogenic exposure ages of 21 erratics from cirque-valley systems and paleo-glacier climate modelling in the High Atlas Mountains, Morocco (31.1° N, 7.9° W), provides new and novel insights as to the history and evolution of the largest desert region on Earth. The Atlas Mountains display evidence of extensive and multiple Late Pleistocene glaciations whose extent is significantly larger than that recognised by previous workers. The largest glaciers formed in the Toubkal massif where we find 3 distinct phases of glacial advances within the last glacial cycle. The oldest moraines occurring at the lowest elevations have yielded eight 10Be ages ranging from 30 to 88 ka. Six of eight samples from moraines at intermediate elevations gave ages of 19 to 25 ka (2 outliers) which correlates well with the global Last Glacial Maximum (ca. 26-21 ka) and the last termination during marine isotope stage 2. Five erratics from the youngest and most elevated moraines yielded a suite of normally distributed exposure ages from 11 to 13 ka which supports a correlation with the northern hemisphere Younger Dryas (12.9-11.7 ka). The glacial record of the High Atlas effectively reflects moisture supply to the north-western Sahara Desert and can provide an indication of shifts between arid and pluvial conditions. The plaeo equilibrium line altitudes (ELA) of these three glacier phases was more than 1000 m lower than the predicted ELA based on today's temperatures. Glacier-climate modelling indicates that for each of these glacier phases climate was not only significantly cooler than today, but also much wetter. The new evidence on the extent, timing and palaeoclimatic significance of glaciations in this region has major implications for understanding moisture transfer between the North Atlantic Ocean and the Sahara Desert during Pleistocene cold stages.

  17. Glacial-interglacial Variations of Molybdenum Isotopes in the Peruvian Oxygen Minimum Zone

    Science.gov (United States)

    Siebert, C.; Frank, M.; Scholz, F.

    2015-12-01

    Mo isotopes have been widely used as a tool to constrain redox-conditions during major global events such as the oxygenation of the oceans in the Precambrian and Cretaceous Ocean Anoxic Events. In addition, Mo isotopes have considerable, yet underexplored potential to quantitatively track local redox-variation at high resolution on shorter timescales. Here we present data from piston core M77/2-024-5 that was retrieved in the Peruvian oxygen minimum zone in the context of Collaborative Research Centre (SFB) 754 of the Deutsche Forschungs Gemeinschaft (DFG). The age model for this core is well constrained and the core covers the last 140 ka with a hiatus between 20 and 50 ky BP. The oxygen minimum zone along the Peru continental margin is thought to have been better ventilated and therefore less pronounced during glacial periods compared to interglacials. Concentrations of redox-sensitive trace elements show high-amplitude changes and indicate periods of strongly sulphidic conditions with high Mo fixation rate and oxygenated periods with limited Mo fixation (Scholz et al 2014). Mo isotopes do not show straightforward correlations with elemental redox tracers and are only weakly correlated with Mo/U and total organic carbon (TOC). However, Mo isotopes become significantly heavier around the last glacial maximum (Δ98Mo of 0.4 permil). The observed signatures indicate that the Mo isotope composition is dominated by changes in the operating Mo delivery mechanism, i.e. particulate transport versus molecular diffusion. Our results suggest that Mo isotopes can track local redox variation therefore adding to our understanding of this complex indicator for marine environmental change. Scholz et al., (2014), Nature Geosciences, Vol. 7, Pages 433-437

  18. Millennial-scale climate variability in response to changing glacial and orbital boundary conditions during the Mid-Pleistocene transition

    Science.gov (United States)

    Ferretti, Patrizia; Crowhurst, Simon; Drysdale, Russell; Bajo, Petra; Barbante, Carlo

    2016-04-01

    The Mid-Pleistocene transition represents perhaps the most important climate transition in the Quaternary period, yet it is one of the most poorly understood. Although the exact timing and mechanism of the onset of the "100 kyr" regime remain a matter of debate, it is well established that the overall periodicity of the glacial-interglacial cycles changed from a dominant 41 kyr obliquity periodicity prior to ~0.9 Ma to a dominant late Pleistocene 100 kyr variance. This change in the frequency domain was associated with an increase in the amplitude of global ice volume variations that, superimposed on a long-term climatic trend towards more glacial conditions over millions of years, produced some of the most extreme glaciations recorded. This interval of time has often been considered to be important in relation to long-term Milankovitch-scale climate variability. In contrast, here, special emphasis will be placed on assessing the presence and the characteristics of the suborbital-scale variability, and reconstructing the evolution of millennial-scale climate variability as the average climate state evolve toward generally colder conditions with larger ice sheets, and the spectral character of climate variability shifted from dominantly 41 kyr to 100 kyr. Appealing evidence suggests that millennial-scale climate variability is amplified during times of intense forcing changes, but this rapid variability has not been thoroughly explored yet at the time when the major changes in climate periodicity occurred. To address these questions, we have examined the record of climatic conditions from Marine Isotope Stages 25 to 16 (~970-650 ka) using high-resolution stable isotope records from benthic and planktonic foraminifera from a sedimentary sequence in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313) in order to assess millennial-scale changes in sea-surface and deep-water conditions, the dynamics of thermohaline deep-water circulation

  19. [Academic essential views on three kinds of bone-setting works published in Edo-period of Japan].

    Science.gov (United States)

    Li, Qiang

    2011-09-01

    The ancient Japanese bone-setting therapy originated from the ancient Chinese bone-setting therapy. This paper gave an introduction to three works published in Edo-period of Japan. Each of them has been regarded as the cornerstone of the Japanese bone-setting therapy: KOUSHI Houyoku Honetsugiryojichouhouki (1746), YOSHIHARA Motomune Kyoinsaiseikotsuyouketsu (1789-1800) and NINOMIYA Genka Seikotsuhan (1808). This article also discussed the academic relationship between these three works and the ancient Chinese bone-setting therapy.

  20. Pleistocene glacial evolution of Fuentes Carrionas (Cantabrian Range, NW Spain)

    Science.gov (United States)

    Pellitero, Ramon

    2014-05-01

    Fuentes Carrionas is a massif situated at the N of Spain, between Castilla y Leon and Cantabria regions. It is the second highest mountain massif of the Cantabrian Range after Picos de Europa, with peaks over 2500 m.a.s.l. and valleys well over 1000 m.a.s.l. Fuentes Carrionas was glaciated during Quaternary, and even during the Holocene and as far as Little Ice Age the presence of glaciers, or at least permafrost is controversial. Results from glacial geomorphology analysis of Fuentes Carrionas Massif are presented. Based on the interpretation of glacial landforms, glacial evolution since the Last Glacial Maximum until Pleistocene deglaciation is described. Four different glacial equilibrium phases are identified, the last one divided into two pulsations. Deglaciation process took place between 36 ka BP and 11 ka BP. Local Last Glacial Maximum is dated back to 36-38 ka. BP, therefore earlier than LGM. Glaciers reached 15 km. long and occupied valleys down to 1250 m.a.s.l. during this phase. By European LGM (20-18 ka.BP) glaciers had substantially retreated to fronts about 1700 m.a.s.l. A final stage with two marked pulsations shows only small glaciers located at cirques above 2000 m.a.s.l. and, finally, only small cirque glaciers at North and Northeast orientation above 2200 m.a.s.l. Both these phases have been correlated to Oldest and Younger Dryas, although no dates have been done yet. A palaeoenvironmental reconstruction is proposed, based on ELA (Equilibrium Line Altitude) rise. ELA has been calculated with the AAR method and 0.67 ratio. This reconstruction shows that temperatures ranged between 9°C and 10°C lower than present ones at the end of Pleistocene, depending on a precipitations variation between 30% higher and 20% lower than current ones. Further research will focus on these retreat phases, especially on Younger Dryas identification and reconstruction for this site and the rest of Cantabrian Range.

  1. Glacially induced stresses in sedimentary rocks of northern Poland

    Science.gov (United States)

    Trzeciak, Maciej; Dąbrowski, Marcin

    2016-04-01

    During the Pleistocene large continental ice sheets developed in Scandinavia and North America. Ice-loading caused bending of the lithosphere and outward flow in the mantle. Glacial loading is one of the most prominent tectono-mechanical event in the geological history of northern Poland. The Pomeranian region was subjected several times to a load equivalent of more than 1 km of rocks, which led to severe increase in both vertical and horizontal stresses in the upper crustal rocks. During deglaciation a rapid decrease in vertical stress is observed, which leads to destabilization of the crust - most recent postglacial faults scarps in northern Sweden indicate glacially induced earthquakes of magnitude ~Mw8. The presence of the ice-sheet altered as well the near-surface thermal structure - thermal gradient inversion is still observable in NW Poland. The glacially related processes might have left an important mark in the sedimentary cover of northern Poland, especially with regard to fracture reopening, changes in stress state, and damage development. In the present study, we model lithospheric bending caused by glacial load, but our point of interest lies in the overlying sediments. Typical glacial isostatic studies model the response of (visco-) elastic lithosphere over viscoelastic or viscous asthenosphere subjected to external loads. In our model, we introduce viscoelastic sedimentary layers at the top of this stack and examine the stress relaxation patterns therein. As a case study for our modelling, we used geological profiles from northern Poland, near locality of Wejherowo, which are considered to have unconventional gas potential. The Paleozoic profile of this area is dominated by almost 1 km thick Silurian-Ordovician shale deposits, which are interbedded with thin and strong limestone layers. This sequence is underlain by Cambrian shales and sandstones, and finally at ~3 km depth - Precambrian crystalline rocks. Above the Silurian there are approximately

  2. Paleo-Environmental Reconstruction Using Ancient DNA

    DEFF Research Database (Denmark)

    Pedersen, Mikkel Winther

    The aim of this thesis has been to investigate and expand the methodology and applicability for using ancient DNA deposited in lake sediments to detect and determine its genetic sources for paleo-environmental reconstruction. The aim was furthermore to put this tool into an applicable context...... solving other scientifically interesting questions. Still in its childhood, ancient environmental DNA research has a large potential for still developing, improving and discovering its possibilities and limitations in different environments and for identifying various organisms, both in terms...... of the sampling methods and strategies (taphonomic processes), the more fundamental molecular methodologies (e.g. extraction and sequencing) and eventually the bioinformatic processing. In the enclosed studies we have tried to take some principal steps towards improving this, firstly by reviewing previous...

  3. Human evolution: a tale from ancient genomes.

    Science.gov (United States)

    Llamas, Bastien; Willerslev, Eske; Orlando, Ludovic

    2017-02-05

    The field of human ancient DNA (aDNA) has moved from mitochondrial sequencing that suffered from contamination and provided limited biological insights, to become a fully genomic discipline that is changing our conception of human history. Recent successes include the sequencing of extinct hominins, and true population genomic studies of Bronze Age populations. Among the emerging areas of aDNA research, the analysis of past epigenomes is set to provide more new insights into human adaptation and disease susceptibility through time. Starting as a mere curiosity, ancient human genetics has become a major player in the understanding of our evolutionary history.This article is part of the themed issue 'Evo-devo in the genomics era, and the origins of morphological diversity'.

  4. Lipids of aquatic sediments, recent and ancient

    Science.gov (United States)

    Eglinton, G.; Hajibrahim, S. K.; Maxwell, J. R.; Quirke, J. M. E.; Shaw, G. J.; Volkman, J. K.; Wardroper, A. M. K.

    1979-01-01

    Computerized gas chromatography-mass spectrometry (GC-MS) is now an essential tool in the analysis of the complex mixtures of lipids (geolipids) encountered in aquatic sediments, both 'recent' (less than 1 million years old) and ancient. The application of MS, and particularly GC-MS, has been instrumental in the rapid development of organic geochemistry and environmental organic chemistry in recent years. The techniques used have resulted in the identification of numerous compounds of a variety of types in sediments. Most attention has been concentrated on molecules of limited size, mainly below 500 molecular mass, and of limited functionality, for examples, hydrocarbons, fatty acids and alcohols. Examples from recent studies (at Bristol) of contemporary, 'recent' and ancient sediments are presented and discussed.

  5. Segmentation of Ancient Telugu Text Documents

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao A.V

    2012-07-01

    Full Text Available OCR of ancient document images remains a challenging task till date. Scanning process itself introduces deformation of document images. Cleaning process of these document images will result in information loss. Segmentation contributes an invariance process in OCR. Complex scripts, like derivatives of Brahmi, encounter many problems in the segmentation process. Segmentation of meaningful units, (instead of isolated patterns, revealed interesting trends. A segmentation technique for the ancient Telugu document image into meaningful units is proposed. The topological features of the meaningful units within the script line are adopted as a basis, while segmenting the text line. Horizontal profile pattern is convolved with Gaussian kernel. The statistical properties of meaningful units are explored by extensively analyzing the geometrical patterns of the meaningful unit. The efficiency of the proposed algorithm involving segmentation process is found to be 73.5% for the case of uncleaned document images.

  6. Periodic behaviors

    CERN Document Server

    Napp, Diego; Shankar, Shiva

    2010-01-01

    This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R^n. These properties - in particular the Nullstellensatz describing the Willems closure - are closely related to integral and rational points on affine algebraic varieties.

  7. PERIODIC BEHAVIORS

    NARCIS (Netherlands)

    Napp, Diego; Put, Marius van der; Shankar, Shiva

    2010-01-01

    This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R(n). These properties-in particular the Nullste

  8. The ancient Greeks present: Rational Trigonometry

    CERN Document Server

    Wildberger, N J

    2008-01-01

    Pythagoras' theorem, the area of a triangle as one half the base times the height, and Heron's formula are amongst the most important and useful results of ancient Greek geometry. Here we look at all three in a new and improved light, using quadrance not distance. This leads to a simpler and more elegant trigonometry, in which angle is replaced by spread, and which extends to arbitrary fields and more general quadratic forms.

  9. Computed tomography of ancient Egyptian mummies.

    Science.gov (United States)

    Harwood-Nash, D C

    1979-12-01

    This first report of the application of computed tomography (CT) to the study of ancient mummies, the desiccated brain of a boy and the body of a young woman within her cartonnage, shows that CT is uniquely suitable for the study of such antiquities, a study that does not necessitate destruction of the mummy or its cartonnage. Exquisite images result that are of great paleoanatomical, paleopathological, and archeological significance.

  10. Volatile and Isotopic Imprints of Ancient Mars

    Science.gov (United States)

    Mahaffy, Paul R.; Conrad, Pamela G.

    2015-01-01

    The science investigations enabled by Curiosity rover's instruments focus on identifying and exploring the habitability of the Martian environment. Measurements of noble gases, organic and inorganic compounds, and the isotopes of light elements permit the study of the physical and chemical processes that have transformed Mars throughout its history. Samples of the atmosphere, volatiles released from soils, and rocks from the floor of Gale Crater have provided a wealth of new data and a window into conditions on ancient Mars.

  11. Ancient News: HMGBs are Universal Sentinels

    Institute of Scientific and Technical Information of China (English)

    Marco E. Bianchi; Barbara Celona

    2010-01-01

    @@ Yanai et al. (2009, Nature 462, 99-103) have shown that high mobility group boxs (HMGBs) are universal sensors of viral nucleic acids, and thus of cell infection. This appears to be an evolutionary ancient mechanism of virus detection, and possibly might be a facet of a more general propensity of HMGBs to act as integrators of signals that pertain to peace and stress, life and death.

  12. Glacial to Holocene climate changes in Easter Island (SE Pacific, 27

    Science.gov (United States)

    Sáez, A.; Giralt, S.; Valero-Garcés, B. L.; Moreno, A.; Bao, R.; Pueyo, J. J.; Hernández, A.

    2009-04-01

    Sedimentary architecture and paleoclimate for the last 34 000 cal years BP and human activity during the last 850 years have been reconstructed from the Raraku Lake sediments in Easter Island (SE Pacific, 27°S) using a high-resolution multiproxy study of 8 cores, 36 AMS radiocarbon dates and correlation with previous core studies. The Last Glacial period was characterized by cold and relatively humid conditions between 34 to 28 cal kyr BP. High lake levels and clastic input dominated sedimentation in Raraku Lake and a relatively open forest developed at that time. Between 28 and 17.3 cal kyr BP, including LGM period, colder conditions contributed to a reduction of the tree coverage in the island. The end of Glacial Period occurred at 17.3 cal kyr BP and was characterized by a sharp decrease in lake level conducive to the development of major floods due to the erosion of littoral sediments. The Deglaciation Period (Termination 1) occurred between 17.3 and 12.5 cal kyr BP, characterized by an increase in lake productivity, a decrease in the terrigenous input and a rapid lake level recovery inaugurating a period of intermediate lake levels. During this period, the dominance of algal lamination is interpreted as a warmer climate. The timing and duration of this warming trend in Easter Island broadly agrees with other mid- and low latitude circum South Pacific terrestrial records. The early Holocene was characterized by low lake levels. The lake level dropped during the early Holocene (ca. 9.5 cal kyr BP) and peatbog and shallow lake conditions dominated till mid Holocene, partially caused by the colmatation of the lacustrine basin. During the mid Holocene an intense drought occurred that led to a persistent low water table period, subaerial exposure and erosion of some of the sediments, generating a sedimentary gap in the Raraku sequence, from 4.2 to 0.8 cal kyr BP. The palm deforestation of the Easter Island, attributed to the human colonization at about 850 cal yr

  13. Ice stream behaviour in the western sector of the North Sea during the end of the last glacial cycle

    Science.gov (United States)

    Roberts, David; Evans, David; Clark, Chris; Bateman, Mark; Livingstone, Stephen; Medialdea, Alicia; Cofaigh, Colm O.; Grimoldi, Elena; Callard, Louise; Dove, Dayton; Stewart, Heather; Davies, Bethan; Chiverell, Richard

    2016-04-01

    During the last glacial cycle the East coast of the UK was overrun by the British-Irish Ice Sheet (BIIS) flowing eastwards and southwards. In recent years it has become evident that several ice streams including the Tweed, Tyne, and Stainmore Gap ice streams, as well as the late stage North Sea Lobe (NSL), all played a role in shaping the glacial landscape during this period, but understanding the flow phasing of these ice streams during advance and collapse has proved challenging. Here we present new data from the seafloor collected during recent work undertaken by the Britice Chrono and Glanam project teams during cruise JC123 in the North Sea. Sub-bottom seafloor data together with new swath data clearly show that the final phases of the collapse of the NSL were controlled by ice sourced from the Firth of Forth ice stream which deglaciated in a NNW trajectory. Other ice streams being fed from the west (e.g. Stainmore, Tyne, Tweed) were not influential in final phase ice retreat from the southern North Sea. The Forth ice imprint is characterised by several grounding zone/till wedges marking dynamic, oscillatory retreat of the ice as it retreated along an offshore corridor between North Yorkshire and Northumberland. Repeated packages of tills, ice marginal and glaciomarine sediments, which drape glacially scoured bedrock terrain and drumlins along this corridor, point to marine inundation accompanying ice retreat. New TCN ages suggest decoupling of the Tyne Gap ice stream and NSL between 17.8 and 16.5 ka and this coincides with rapid, regional collapse of the NSL between 17.2 and 16.0 ka along the Yorkshire and Durham coasts (new OSL ages; Britice Chrono). Hence, both the central and northern sectors of the BIIS were being strongly influenced by marine margin instability during the latter phases of the last glacial cycle.

  14. Tombs of the Yelang Period at Kele in Hezhang, Guizhou

    Institute of Scientific and Technical Information of China (English)

    梁太鹤; 亦囡; 曹楠

    2003-01-01

    In September-October 2000, the Guizhou Provincial Institute of Antiquity and Archaeology and Hezhang County Commission for Preservation of Ancient Monuments jointly excavated tombs of the Warring States period to Western Han times at Kele 可乐, Village in Kele Town, Hezhang 赫章 County, Guizhou 贵州 and reaped great fruits. Due to the tombs are of the ancient Yelang period and the burial custom and funerary objects have distinctive local ethnic features, the excavation aroused more interest in the academic circle.

  15. Geometric back-analysis of ancient rockslides in Tafjord (Norway)

    Science.gov (United States)

    Oppikofer, T.; Jaboyedoff, M.; Derron, M.-H.; Blikra, L. H.

    2009-04-01

    In the past, numerous large rockslides occurred in the Norwegian fjords and that caused catastrophic tsunamis in the narrow fjords. 12 post-glacial rockslide deposits are found in the Tafjord fjord in Western Norway. Amongst them are the deposits of the 1934 Langhammaren rockslide, which created a tsunami wave with a run-up of up to 63 m and killed 40 people in nearby villages. Since 2005 potential rock slope instabilities in the Tafjord area are investigated within the Åknes/Tafjord project. The scope of this study is the detection of past rockslides and to back-analyse these events using a high-resolution digital elevation model (HRDEM) derived from aerial laser scanning, orthophotos, and field mapping. Hillshade maps coupled with field data enabled the characterization of 17 past rockslide scars (including the 1934 event) that were mainly constituted of orthogneisses and augengneisses. The spatial orientations of major discontinuity sets and the relevant rockslide structures, i.e. the basal sliding surface, the lateral auxiliary sliding surface, the lateral release surface(s), and the back-scar(s), were calculated using Coltop3D software and the HRDEM. This analysis showed the pre-dominant role of the main foliation that dips towards the South with a dip angle of 37° to 63°. The foliation generally formed the basal sliding surface, while the other discontinuity sets controlled the orientation of other main rockslide structures. In order to compute the volume of ancient rockslides, the pre-rockslide topography was reconstructed by fitting planes on the surroundings of the scars using PolyWorks® software. The orientation of these planes was constrained by the orientation of major discontinuity sets. The rockslide volumes were computed by subtracting the present HRDEM from the pre-rockslide DEM. The volumes range from 29000 m³ up to 63.5 million m³ for Langhammaren area. The Langhammaren area led to several rockslides, including the 1934 event with a computed

  16. 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

  17. Palaeogeographic regulation of glacial events during the Cretaceous supergreenhouse

    Science.gov (United States)

    Ladant, Jean-Baptiste; Donnadieu, Yannick

    2016-09-01

    The historical view of a uniformly warm Cretaceous is being increasingly challenged by the accumulation of new data hinting at the possibility of glacial events, even during the Cenomanian-Turonian (~95 Myr ago), the warmest interval of the Cretaceous. Here we show that the palaeogeography typifying the Cenomanian-Turonian renders the Earth System resilient to glaciation with no perennial ice accumulation occurring under prescribed CO2 levels as low as 420 p.p.m. Conversely, late Aptian (~115 Myr ago) and Maastrichtian (~70 Myr ago) continental configurations set the stage for cooler climatic conditions, favouring possible inception of Antarctic ice sheets under CO2 concentrations, respectively, about 400 and 300 p.p.m. higher than for the Cenomanian-Turonian. Our simulations notably emphasize that palaeogeography can crucially impact global climate by modulating the CO2 threshold for ice sheet inception and make the possibility of glacial events during the Cenomanian-Turonian unlikely.

  18. Glacial flutings in bedrock, an observation in East Greenland

    DEFF Research Database (Denmark)

    Funder, Svend Visby

    1978-01-01

    Large scale glacial flutings cover an area of 4 x 1.5 km on the northern shore of Harefjord in the interior Scoresby Sund fjord complex. The flutings are modelled in coarse sandstone and conglomerates, a few small features are probably composed of till. The ridges measure up to' 2000 m in length...... and 5 m in height and occur between 50 and 250 m above sea level inthe gently sloping lowland area adjacent to the fjord. They were probably formed beneath the lateral part of the former Harefjord-Glacier which receded rapidly in the fjord and exposed the area at c. 7500 years BP. Large scale glacial...... flutings have not been recorded before in Greenland, but seem to be of common occurrence in parts of North America. They have probably been formed near the margin of actively moving glaciers, and secondary flow in the basal ice may have played an important role...

  19. Modeling glacial flow on and onto Pluto's Sputnik Planum

    CERN Document Server

    Umurhan, O M; Moore, J M; Earle, A M; Binzel, R P; Stern, S A; Schenk, P M; Beyer, R A; White, O L; NImmo, F; McKinnon, W B; Ennico, K; Olkin, C B; Weaver, H A; Young, L A

    2016-01-01

    Observations of Pluto's surface made by the New Horizons spacecraft indicates present-day nitrogen ice glaciation in and around the basin known as Sputnik Planum. Motivated by these observations, we have developed an evolutionary glacial flow model of solid nitrogen ice taking into account its published thermophysical and rheologies properties. This model assumes that glacial ice layers flow laminarly and have low aspect ratios which permits a vertically integrated mathematical formulation. We assess the conditions for the validity of laminar nitrogen ice motion by revisiting the problem of the onset of solid-state buoyant convection of nitrogen ice for a variety of bottom thermal boundary conditions. Subject to uncertainties in nitrogen ice rheology, nitrogen ice layers are estimated to flow laminarly for thicknesses less than 400-1000 meters. The resulting mass-flux formulation for when the nitrogen ice flows as a laminar dry glacier is characterized by an Arrhenius-Glen functional form. The flow model deve...

  20. Ancient peat and apple extracts supplementation may improve strength and power adaptations in resistance trained men

    OpenAIRE

    Joy, Jordan M; Vogel, Roxanne M.; Moon, Jordan R; Falcone, Paul H; Matt M Mosman; Pietrzkowski, Zbigniew; Reyes, Tania; Michael P. Kim

    2016-01-01

    Background Increased cellular ATP levels have the potential to enhance athletic performance. A proprietary blend of ancient peat and apple extracts has been supposed to increase ATP production. Therefore, the purpose of this investigation was to determine the effects of this supplement on athletic performance when used during 12 weeks of supervised, periodized resistance training. Methods Twenty-five healthy, resistance-trained, male subjects completed this study. Subjects supplemented once d...