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Susan Ivyochs - One of the best experts on this subject based on the ideXlab platform.
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new geomorphological and chronological constraints for glacial deposits in the rivoli avigliana end moraine system and the lower susa valley western alps nw italy
Journal of Quaternary Science, 2018Co-Authors: Susan Ivyochs, Naki Akcar, Franco Gianotti, Giovanni Monegato, Stefania Lucchesi, Paolo Baggio, Gianfranco Fioraso, Angela A Graf, Marcus Christl, F CarraroAbstract:Our new dataset from the Rivoli‐Avigliana end‐moraine system, the westernmost amphitheatre of the Italian Alps, provides an important step towards understanding foreland‐reaching glaciations before and during the Last Glacial Maximum (LGM) in the Western Alps. 10Be data from six boulders in pre‐LGM deposits gave ages between 26.8 ± 2.1 and 41.2 ± 1.9 ka. Based on morphological and pedological data, we interpret the oldest age as a minimum age for the Glacier Advance(s). 10Be results suggest that the LGM occurred in two major steps. During the first at 24.0 ± 1.5 ka, several ridges were constructed demonstrating oscillation of the Dora Riparia Glacier snout at the maximum position. Our data demonstrate a significantly larger LGM extent in the Rivoli‐Avigliana amphitheatre than shown on previous maps. The maximum Advance was followed by a short re‐Advance of the Glacier at 19.6 ± 0.9 ka, as recorded by 10Be ages from boulders in lateral positions along the lower Susa Valley. The maximum ice surface during the LGM was at 1000–920 m a.s.l. in the final reach of the valley (560–620 m of elevation above the alluvial plain) and at 620–340 m a.s.l. at the continuous moraines in the amphitheatre.
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landslide deposits as stratigraphical markers for a sequence based glacial stratigraphy a case study of a younger dryas system in the eastern alps
Boreas, 2016Co-Authors: Mathias Bichler, Marcus Christl, Martin Reindl, Jurgen M Reitner, Ruth Drescherschneider, Christian Wirsig, Irka Hajdas, Susan IvyochsAbstract:Detailed 10Be and 14C dating and supporting pollen analysis of Alpine Lateglacial glacial and landslide deposits in the Hohen Tauern Mountains (Austria) constrain a sequence-based stratigraphy comprising a major landslide (13.0±1.1 ka) overlain by till and termino-lateral moraines of an advancing (12.6±1.0 ka) and retreating (11.3±0.8 ka) Glacier in turn overlain by a minor landslide (10.8±1.1 ka). These results define Glacier activity during the Younger Dryas age Egesen stadial bracketed by landslide activities during the Bolling-Allerod interstadial and the Preboreal. In contrast to recent studies on Holocene glaciation in the Alps, no traces of any Holocene Glacier Advance bigger than during the Little Ice Age are documented. Furthermore, this study demonstrates the advantages of using an allostratigraphical approach based on unconformity-bounded sedimentary units as a tool for glacial stratigraphy in formerly glaciated mountain regions, rather than a stratigraphy based on either isolated morphological features or lithostratigraphical characteristics.
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a chronology of holocene and little ice age Glacier culminations of the steingletscher central alps switzerland based on high sensitivity beryllium 10 moraine dating
Earth and Planetary Science Letters, 2014Co-Authors: Susan Ivyochs, Naki Akcar, Joerg M Schaefer, Irene Schimmelpfennig, Tobias N B Koffman, R Schwartz, R C FinkelAbstract:Abstract The amplitude and timing of past Glacier culminations are sensitive recorders of key climate events on a regional scale. Precisely dating young moraines using cosmogenic nuclides to investigate Holocene Glacier chronologies has proven challenging, but progress in the high-sensitivity 10 Be technique has recently been shown to enable the precise dating of moraines as young as a few hundred years. In this study we use 10 Be moraine dating to reconstruct culminations of the Steingletscher, a small mountain Glacier in the central Swiss Alps, throughout the Holocene. The outermost-recorded positions of Steingletscher most likely occurred in the Early Holocene and appear nearly synchronous with Glacier culminations reported from other regions in the Alps. A Late-Holocene position corroborates the evidence for a significant Glacier Advance of similar extent to that of the Little Ice Age (LIA) ∼ 3 kyr ago. Finally, fourteen boulders from different moraines yield 10 Be ages between 580 and 140 years with analytical precisions mostly 10 % , dating Steingletscher Advances during the LIA. Because these LIA 10 Be ages are in stratigraphic order, we tentatively distinguish four LIA Glacier culminations: about 1470 CE, 1650 CE, 1750 CE and 1820 CE, which are in good agreement with existing independent records during the LIA in the Swiss Alps. These findings illustrate the high potential of the 10 Be moraine dating method to directly link paleo-Glacier-chronologies to historical records and thus present-day Glacier evolution.
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10be dating of the end of low altitude rock Glacier activity in the alps evidence for cold conditions during the early preboreal
EGUGA, 2010Co-Authors: Hanns Kerschner, Susan IvyochsAbstract:Large relict rock Glacier complexes are conspicious features in the Alps. Their occurence can roughly be subdivided into a "lower rock Glacier belt", which reaches down to about 1900 m a.s.l., an "intermediate rock Glacier belt" with rock Glacier snouts at around present-day timberline (approx. 2200 m a.s.l) in the central Alps and an "upper rock Glacier belt" at similar altitudes as presently active rock Glaciers. All these rock Glaciers indicate the former presence of discontinuous permafrost at their respective altitudes and are good indicators for the mean annual air temperature during their active period. The end of rock Glacier activity at a given altitude marks also the end of the existence of permafrost conditions. Experience from the Alps shows that it may take about a century until the surface of a rock Glacier is stabilized, Hence, if it is possible to date the surface of a relict rock Glacier with 10Be, we get a close date for the end of permafrost activity at the altitude of the rock Glacier. From the difference between the altitude of the relict rock Glacier and presently active rock Glaciers, the rise of mean annual air temperature can be calculated. Relict rock Glaciers at present-day timberline at Julierpass (Swiss Alps) and at Larstigtal (Austrian Alps) gave ages in the order of 10.5 ka BP for surface stabilization. Both rock Glaciers, which belong to the "intermediate rock Glacier belt", developed from lateral moraines and scree slopes. They started to move into former Glacier beds after ice recession from the Younger Dryas "Egesen" Advance. Their age indicates that climatic conditions favouring permafrost existence about 300 400 m below 20th century permafrost occurence prevailed during most of the Preboreal. Taken together with the Kartell Glacier Advance (10.8 ka) they show that rapid climatic warming at the Younger Dryas / Holocene boundary was followed by more unstable climatic conditions and and somewhat slower warming until full Holocene climatic conditions were reached by ca. 10.5 ka or perhaps a little earlier. Mean annual air temperatures should have been about 2.5 K lower than during the 20th century. Since then, there has been no time window long enough to allow the formation of large rock Glaciers at low altitudes.
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chronology of the last glacial cycle in the european alps
Journal of Quaternary Science, 2008Co-Authors: Susan Ivyochs, Hanns Kerschner, Peter W Kubik, Anne U Reuther, Frank Preusser, Klaus Heine, Max Maisch, Christian SchluchterAbstract:Chronological data for Glacier Advances in the European Alps between the Last Interglacial (Eemian) and the Holocene are summarised (115 to 11 ka). During this time Glaciers were most extensive, extending tens of kilometres out onto the forelands, between 30 and 18 ka, that is, synchronous with the global ice volume maximum of Marine Isotope Stage (MIS) 2. Evidence for ice expanding to just past the mountain front for an earlier major Glacier Advance comes from Swiss sites, where Advances have been luminescence dated to MIS 5d (100 ka) and MIS 4 (70 ka). Up to now no such evidence has been found in the Eastern Alps. By 18 ka, more than 80% of the Late Wurmian ice volume had gone. Subsequently Glaciers reAdvanced, reaching into the upper reaches of the main valleys during the Lateglacial Gschnitz stadial, which likely occurred around 17 ka, with final moraine stabilisation no later than 15.4 ka. The link of the Egesen stadial with the Younger Dryas climate deterioration is supported by exposure ages from four sites as well as minimum-limiting radiocarbon dates from bogs within former Glacier tongue areas. Key questions on the spatial and temporal variability of ice extents throughout the last glacial cycle have yet to be answered. Copyright © 2008 John Wiley & Sons, Ltd.
Simon L Pendleton - One of the best experts on this subject based on the ideXlab platform.
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Glacier expansion on baffin island during early holocene cold reversals
Quaternary Science Reviews, 2020Co-Authors: Sarah E Crump, Robert S. Anderson, Nicolas E Young, Gifford H Miller, Simon L Pendleton, Joseph P Tulenko, Jason P BrinerAbstract:Abstract The North Atlantic was a key locus for circulation-driven abrupt climate change in the past and could play a similar role in the future. Abrupt cold reversals, including the 8.2 ka event, punctuated the otherwise warm early Holocene in the North Atlantic region and serve as useful paleo examples of rapid climate change. In this work, we assess the cryospheric response to early Holocene climate history on Baffin Island, Arctic Canada, using cosmogenic radionuclide dating of moraines. We present 39 new 10Be ages from four sets of multi-crested early Holocene moraines deposited by cirque Glaciers and ice cap outlet Glaciers, as well as erratic boulders along adjacent fiords to constrain the timing of regional deglaciation. The age of one moraine is additionally constrained by in situ 14C measurements, which confirm 10Be inheritance in some samples. All four moraines were deposited between ∼9.2 and 8.0 ka, and their average ages coincide with abrupt coolings at 9.3 and 8.2 ka that are recorded in Greenland ice cores. Freshwater delivery to the North Atlantic that reduced the flux of warm Atlantic water into Baffin Bay may explain brief intervals of Glacier Advance, although moraine formation cannot be definitively tied to centennial-scale cold reversals. We thus explore other possible contributing factors, including ice dynamics related to retreat of Laurentide Ice Sheet outlet Glaciers. Using a numerical Glacier model, we show that the debuttressing effect of trunk valley deglaciation may have contributed to these moraine-building events. These new age constraints and process insights highlight the complex behavior of the cryosphere during regional deglaciation and suggest that multiple abrupt cold reversals—as well as deglacial ice dynamics—likely played a role in early Holocene moraine formation on Baffin Island.
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Deglaciation of the Greenland and Laurentide ice sheets interrupted by Glacier Advance during abrupt coolings
Quaternary Science Reviews, 2020Co-Authors: Nicolas E Young, Sarah E Crump, Gifford H Miller, Simon L Pendleton, Jason P Briner, Alia J. Lesnek, Elizabeth K. Thomas, Joshua K. Cuzzone, J. L. Lamp, Susan ZimmermanAbstract:Abstract Understanding patterns of ice-sheet deglaciation is key for predicting the rate of future ice-sheet melt, yet the processes underlying deglaciation remain elusive. The early Holocene (11.7 ka to 8.2 ka; Greenlandian Stage) represents the most recent period when the Laurentide and Greenland ice sheets underwent large-scale recession. Moreover, this ice-sheet recession occurred under the backdrop of regional temperatures that were similar to or warmer than today, and comparable to those projected for the upcoming centuries. Reconstructing Laurentide and Greenland ice sheet behavior during the early Holocene, and elucidating the mechanisms dictating this behavior may serve as a partial analog for future Greenland ice-sheet change in a warming world. Here, we present 123 new 10Be surface exposure ages from two sites on Baffin Island and southwestern Greenland that constrain the behavior of the Laurentide and Greenland ice sheets, and an independent alpine Glacier during the early Holocene. On Baffin Island, we focus on a unique area where moraines deposited by the Laurentide Ice Sheet rest directly adjacent to moraines deposited by an independent alpine Glacier. Sixty-one 10Be ages reveal that Advances and/or stillstands of the Laurentide Ice Sheet and an alpine Glacier occurred in unison around 11.8 ka, 10.3 ka, and 9.2 ka. Sixty-two 10Be ages from southwestern Greenland indicate that the Greenland Ice Sheet margin experienced re-Advances or stillstands around 11.6 ka, 10.4 ka, 9.1 ka, 8.1 ka, and 7.3 ka. Our results reveal that ice sheets respond to climate perturbations on the same centennial timescale as small alpine Glaciers. We hypothesize that during the warming climate of the early Holocene, freshening of the North Atlantic Ocean induced by ice-sheet melt resulted in regional cooling and brief periods of ice-sheet stabilization superimposed on net Glacier recession. These observations point to a negative feedback mechanism inherent to melting ice sheets in the Baffin Bay region that slows ice-sheet recession during intervals of otherwise rapid deglaciation.
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episodic neoglacial expansion and rapid 20th century retreat of a small ice cap on baffin island arctic canada and modeled temperature change
Climate of The Past, 2017Co-Authors: Simon L Pendleton, Sarah E Crump, Gifford H Miller, Robert A Anderson, Yafang Zhong, Alexandra Jahn, Aslaug GeirsdottirAbstract:Abstract. Records of Neoglacial Glacier activity in the Arctic constructed from moraines are often incomplete due to a preservation bias toward the most extensive Advance, often the Little Ice Age. Recent warming in the Arctic has caused extensive retreat of Glaciers over the past several decades, exposing preserved landscapes complete with in situ tundra plants previously entombed by ice. The radiocarbon ages of these plants define the timing of snowline depression and Glacier Advance across the site, in response to local summer cooling. Erosion rapidly removes most dead plants that have been recently exposed by ice retreat, but where erosive processes are unusually weak, dead plants may remain preserved on the landscape for decades. In such settings, a transect of plant radiocarbon ages can be used to construct a near-continuous chronology of past ice margin Advance. Here we present radiocarbon dates from the first such transect on Baffin Island, which directly dates the Advance of a small ice cap over the past two millennia. The nature of ice expansion between 20 BCE and ∼ 1000 CE is still uncertain, but episodic Advances at ∼ 1000 CE, ∼ 1200, and ∼ 1500 led to the maximum Neoglacial dimensions ~ 1900 CE. We employ a two-dimensional numerical Glacier model calibrated using the plant radiocarbon ages ice margin chronology to assess the sensitivity of the ice cap to temperature change. Model experiments show that at least ∼ 0.44 °C of cooling over the past 2 kyr is required for the ice cap to reach its 1900 CE margin, and that the period from ∼ 1000 to 1900 CE must have been at least 0.25° C cooler than the previous millennium, results that agree with regional temperature reconstructions and climate model simulations. However, significant warming since 1900 CE is required to explain retreat to its present position, and, at the same rate of warming, the ice cap will disappear before 2100 CE.
Hai Cheng - One of the best experts on this subject based on the ideXlab platform.
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cryogenic cave carbonates in the dolomites northern italy insights into younger dryas cooling and seasonal precipitation
Climate of The Past Discussions, 2020Co-Authors: Gabriella Koltai, Christoph Spotl, Hai ChengAbstract:Abstract. In the European Alps, the Younger Dryas (YD) was characterized by the last major Glacier Advance with equilibrium line altitudes being ~ 220 to 290 m lower than during the Little Ice Age and also by the development of rock Glaciers. Dating of these geomorphic features, however, is associated with substantial uncertainties leading to considerable ambiguities on the internal structure of this stadial, the most intensively studied one of the last glacial period. Here we provide robust physical evidence based on precise 230Th-dated cryogenic cave carbonates (CCC) coupled with thermal modelling indicating that early YD winters were only moderately cold in the Southern Alps, challenging the commonly held view of extreme YD seasonality. Our data argue for a negative temperature anomaly of ≤ 3 °C in mean annual air temperature at the Allerod-YD transition in a mountain cave (Cioccherloch, 2274 m a.s.l.) in the Dolomites of northern Italy. Our data suggest that autumns and early winters in the early part of the YD were relatively snow-rich, resulting in a stable winter snow cover. The latter insulated the shallow subsurface in winter and allowed the cave interior to remain close to the freezing point (0 °C) year-round, promoting CCC formation. The main phase of CCCs precipitation at ~ 12.2 ka BP coincides with the mid-YD transition recorded in other archives across Europe. Based on thermal modelling we propose that CCC formation at ~ 12.2 ka BP was most likely associated with a slight warming of approximately +1 °C in conjunction with drier autumns and early winters in the second half of the YD. These changes triggered CCC formation in this alpine cave as well as ice Glacier retreat and rock Glacier expansion in the Alps.
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north atlantic storm track changes during the last glacial maximum recorded by alpine speleothems
Nature Communications, 2015Co-Authors: Marc Luetscher, Ronny Boch, Harald Sodemann, Christoph Spotl, Hai Cheng, Roger Lawrence Edwards, Silvia FrisiaAbstract:Insights into Late-Pleistocene Northern Hemisphere storm track variability are hampered by a lack of well-dated proxy records. Here, the authors present a precisely dated record of meteoric precipitation between 30 and 14.7 ka, and show that obliquity may have played a vital role in Alpine Glacier Advance.
Jason P Briner - One of the best experts on this subject based on the ideXlab platform.
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Glacier expansion on baffin island during early holocene cold reversals
Quaternary Science Reviews, 2020Co-Authors: Sarah E Crump, Robert S. Anderson, Nicolas E Young, Gifford H Miller, Simon L Pendleton, Joseph P Tulenko, Jason P BrinerAbstract:Abstract The North Atlantic was a key locus for circulation-driven abrupt climate change in the past and could play a similar role in the future. Abrupt cold reversals, including the 8.2 ka event, punctuated the otherwise warm early Holocene in the North Atlantic region and serve as useful paleo examples of rapid climate change. In this work, we assess the cryospheric response to early Holocene climate history on Baffin Island, Arctic Canada, using cosmogenic radionuclide dating of moraines. We present 39 new 10Be ages from four sets of multi-crested early Holocene moraines deposited by cirque Glaciers and ice cap outlet Glaciers, as well as erratic boulders along adjacent fiords to constrain the timing of regional deglaciation. The age of one moraine is additionally constrained by in situ 14C measurements, which confirm 10Be inheritance in some samples. All four moraines were deposited between ∼9.2 and 8.0 ka, and their average ages coincide with abrupt coolings at 9.3 and 8.2 ka that are recorded in Greenland ice cores. Freshwater delivery to the North Atlantic that reduced the flux of warm Atlantic water into Baffin Bay may explain brief intervals of Glacier Advance, although moraine formation cannot be definitively tied to centennial-scale cold reversals. We thus explore other possible contributing factors, including ice dynamics related to retreat of Laurentide Ice Sheet outlet Glaciers. Using a numerical Glacier model, we show that the debuttressing effect of trunk valley deglaciation may have contributed to these moraine-building events. These new age constraints and process insights highlight the complex behavior of the cryosphere during regional deglaciation and suggest that multiple abrupt cold reversals—as well as deglacial ice dynamics—likely played a role in early Holocene moraine formation on Baffin Island.
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Deglaciation of the Greenland and Laurentide ice sheets interrupted by Glacier Advance during abrupt coolings
Quaternary Science Reviews, 2020Co-Authors: Nicolas E Young, Sarah E Crump, Gifford H Miller, Simon L Pendleton, Jason P Briner, Alia J. Lesnek, Elizabeth K. Thomas, Joshua K. Cuzzone, J. L. Lamp, Susan ZimmermanAbstract:Abstract Understanding patterns of ice-sheet deglaciation is key for predicting the rate of future ice-sheet melt, yet the processes underlying deglaciation remain elusive. The early Holocene (11.7 ka to 8.2 ka; Greenlandian Stage) represents the most recent period when the Laurentide and Greenland ice sheets underwent large-scale recession. Moreover, this ice-sheet recession occurred under the backdrop of regional temperatures that were similar to or warmer than today, and comparable to those projected for the upcoming centuries. Reconstructing Laurentide and Greenland ice sheet behavior during the early Holocene, and elucidating the mechanisms dictating this behavior may serve as a partial analog for future Greenland ice-sheet change in a warming world. Here, we present 123 new 10Be surface exposure ages from two sites on Baffin Island and southwestern Greenland that constrain the behavior of the Laurentide and Greenland ice sheets, and an independent alpine Glacier during the early Holocene. On Baffin Island, we focus on a unique area where moraines deposited by the Laurentide Ice Sheet rest directly adjacent to moraines deposited by an independent alpine Glacier. Sixty-one 10Be ages reveal that Advances and/or stillstands of the Laurentide Ice Sheet and an alpine Glacier occurred in unison around 11.8 ka, 10.3 ka, and 9.2 ka. Sixty-two 10Be ages from southwestern Greenland indicate that the Greenland Ice Sheet margin experienced re-Advances or stillstands around 11.6 ka, 10.4 ka, 9.1 ka, 8.1 ka, and 7.3 ka. Our results reveal that ice sheets respond to climate perturbations on the same centennial timescale as small alpine Glaciers. We hypothesize that during the warming climate of the early Holocene, freshening of the North Atlantic Ocean induced by ice-sheet melt resulted in regional cooling and brief periods of ice-sheet stabilization superimposed on net Glacier recession. These observations point to a negative feedback mechanism inherent to melting ice sheets in the Baffin Bay region that slows ice-sheet recession during intervals of otherwise rapid deglaciation.
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beryllium 10 chronology of early and late wisconsinan moraines in the revelation mountains alaska insights into the forcing of wisconsinan glaciation in beringia
Quaternary Science Reviews, 2018Co-Authors: Joseph P Tulenko, Nicolas E Young, Jason P Briner, Joerg M SchaeferAbstract:Abstract We present 32 new cosmogenic 10Be exposure ages from a moraine sequence deposited during the Wisconsinan glaciation in the Swift River valley, Revelation Mountains, western Alaska Range. 10Be ages from an early Wisconsinan [Marine Isotope Stage 4] moraine average 59.7 ± 3.6 ka (n = 9; excluding one outlier), and 10Be ages from a late Wisconsinan [Marine Isotope Stage 2] terminal moraine, inboard moraines, and two recessional end moraines average 21.3 ± 0.8 ka (n = 3; excluding two outliers), 20.2 ± 1.0 ka (n = 7; excluding three young outliers), 19.6 ± 1.0 ka (n = 2; excluding one outlier) and 17.7 ± 0.8 ka (n = 4; excluding two outliers), respectively. The early Wisconsinan moraine age coincides with the close of MIS 4, consistent with previous chronologies from Beringia. Whereas Southern Hemisphere Glaciers retreated prior to the onset of Heinrich Stadial 6 (64–60 ka), the MIS 4 Glacier Advance in the Swift River valley terminated at the close of Heinrich Stadial 6, possibly in response to abrupt North Atlantic warming. Our late Wisconsinan ages indicate significant initial Glacier retreat between ca. 21.3–17.7 ka (prior to any significant increase in CO2) likely in response to amplified warming from rising insolation. Preservation of MIS 4 moraines in Beringia has traditionally been ascribed to limited MIS 2 Glacier Advance modulated by low regional moisture availability, stemming from the exposed Bering Land Bridge. However, we hypothesize that atmospheric re-organization forced by the Laurentide Ice Sheet resulted in relatively higher temperatures and drier conditions in Beringia during MIS 2 than MIS 4, allowing for the preservation of early Wisconsinan moraines.
Christian Schluchter - One of the best experts on this subject based on the ideXlab platform.
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chronology of the last glacial cycle in the european alps
Journal of Quaternary Science, 2008Co-Authors: Susan Ivyochs, Hanns Kerschner, Peter W Kubik, Anne U Reuther, Frank Preusser, Klaus Heine, Max Maisch, Christian SchluchterAbstract:Chronological data for Glacier Advances in the European Alps between the Last Interglacial (Eemian) and the Holocene are summarised (115 to 11 ka). During this time Glaciers were most extensive, extending tens of kilometres out onto the forelands, between 30 and 18 ka, that is, synchronous with the global ice volume maximum of Marine Isotope Stage (MIS) 2. Evidence for ice expanding to just past the mountain front for an earlier major Glacier Advance comes from Swiss sites, where Advances have been luminescence dated to MIS 5d (100 ka) and MIS 4 (70 ka). Up to now no such evidence has been found in the Eastern Alps. By 18 ka, more than 80% of the Late Wurmian ice volume had gone. Subsequently Glaciers reAdvanced, reaching into the upper reaches of the main valleys during the Lateglacial Gschnitz stadial, which likely occurred around 17 ka, with final moraine stabilisation no later than 15.4 ka. The link of the Egesen stadial with the Younger Dryas climate deterioration is supported by exposure ages from four sites as well as minimum-limiting radiocarbon dates from bogs within former Glacier tongue areas. Key questions on the spatial and temporal variability of ice extents throughout the last glacial cycle have yet to be answered. Copyright © 2008 John Wiley & Sons, Ltd.
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a case for a downwasting mountain Glacier during termination i vercenik valley northeastern turkey
Journal of Quaternary Science, 2008Co-Authors: Naki Akcar, Susan Ivyochs, Peter W Kubik, Vural Yavuz, Mahir Vardar, Christian SchluchterAbstract:Field evidence of palaeoglacial records in the Vercenik valley in the Eastern Black Sea Mountains was examined and 19 samples for surface exposure dating with cosmogenic 10 Be were collected with the aim of increasing knowledge on the amplitude and frequency of palaeoGlacier Advances in Anatolia. Glacial erosional features were mapped and the flow directions of the palaeoGlaciers were determined. The Vercenik palaeoGlacier Advanced before 26.1 k � 1.2 k yr. The Last Glacial Maximum (LGM) Advance continued until 18.8 k � 1.0 k yr. The Vercenik palaeo- Glacier collapsed during Termination I. After 17.7 k � 0.8 k yr there was no more ice in the main valley. The Vercenik palaeoGlacier most probably then separated into five small Glaciers that were restricted to the tributary valleys. Among these, the Hemsin palaeoGlacier completed its recession around 15.7 k � 0.8 k yr. On the basis of glacial erosion features, a Lateglacial Glacier Advance can be identified. Evidence of the Little Ice Age Advance appears to be absent. The results from this valley system seem to be consistent with the first results from the adjacent Kavron valley and with the Anatolian LGM palaeoclimate, the sea surface temperature minima in the western Mediterranean, the deposition of red clay layers in the Black Sea and deposition of the Heinrich-1 layer in the North Atlantic. Copyright # 2007 John Wiley & Sons, Ltd.
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Glacier response in the european alps to heinrich event 1 cooling the gschnitz stadial
Journal of Quaternary Science, 2006Co-Authors: Susan Ivyochs, Hanns Kerschner, Peter W Kubik, Christian SchluchterAbstract:The Gschnitz stadial was a period of regionally extensive Glacier Advance in the European Alps that lies temporally between the breakdown of the Last Glacial Maximum piedmont lobes and the beginning of the Bolling warm interval. Moraines of the Gschnitz stadial are found in medium to small catchments, are steep-walled and blocky, and reflect a snowline lowering of 650- 700 m in comparison to the Little Ice Age reference snowline. 10 Be surface exposure dating of boulders from the moraine at the type locality at Trins (Gschnitz valley, Tyrol, Austria) shows that it stabilised no later than 15 400 � 1400 yr ago. The overall morphological situation and the long reaction time of the Glacier suggest that the climatic downturn lasted about 500 � 300 yr, indicating that the Gschnitz cold period began approximately 15 900 � 1400 yr ago, if not somewhat earlier. This is consistent with published radiocarbon dates that imply that the stadial occurred sometime between 15 400 14 C yr BP (18 020-19 100 cal. yr) and 13 250 14 C yr BP (15 360-16 015 cal. yr). A palaeoclimatic interpretation of the Gschnitz Glacier based on a simple Glacier flow model and statistical Glacier-climate models shows that precipitation was about one-third of modern-day precipitation and summer temperatures were about 10 K lower than today. In comparison, during the Younger Dryas, precipitation in this area was only about 10% less and Ts (summer temperature) was only 3.5-4 K lower than modern values. Based on the age of the moraine and the cold and dry climate at that time, we suggest that the Gschnitz stadial was the response of Alpine Glaciers to cooling of the North Atlantic Ocean associated with Heinrich Event 1. Copyright 2005 John Wiley & Sons, Ltd.