Retreat dynamics of the eastern sector of the British–Irish Ice Sheet during the last glaciation

ABSTRACT Various glaciotectonic structures and landforms created by ice pushing are common in drift and interstadial sediments in a narrow belt of central Sweden. Described examples from the Lake Storsjôn vicinity demonstrate that glaciotectonic deformation took place while the area was deeply covered by the last Fennoscandian Ice Sheet. Deformation was controlled by pressure gradients related to position of the ice divide and ice movement away from the divide. As the position of the divide shifted during the last glaciation, so did the orientation of glaciotectonic structures. The regional distribution of glaciotectonic features in Fennoscandia falls into three zones: (1) inner zone of widespread, small- to moderate-sized features in older drift, (2) intermediate zone of small, isolated features in drift of the last glaciation, and (3) outer zone with all manner of large and small features in drift and soft bedrock. These zones are the cumulative results of multiple glaciations and reflect the overall distribution of deformable sediment and bedrock within the continental substratum.

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The Disappearance of the Last Ice Sheet from Central Norway

Journal of Glaciology ◽

10.3189/s0022143000025016 ◽

1956 ◽

Vol 2 (20) ◽

pp. 747-755

Author(s):

Kaare Strøm

Keyword(s):

Research Work ◽

Ice Sheet ◽

High Mountains ◽

Last Glaciation ◽

Glacier Ice ◽

Final Degree

AbstractThe lecture was a review of the research work carried out by the author and his collaborators, as well as by J. Gjessing and students working for their final degree. Attention is called to the existence of local centres in western regions even during the maximum of the last glaciation, as well as the transition from down-wasting of dead ice near the ice divide to backward melting of partly active glacier tongues in the high mountains near the sea. Regional reconstructions of the waning of the glacier ice are attempted.

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The glacial geology of northeastern Ellesmere Island, N.W.T., Canada

Canadian Journal of Earth Sciences ◽

10.1139/e78-065 ◽

1978 ◽

Vol 15 (4) ◽

pp. 603-617 ◽

Cited By ~ 39

Author(s):

John England

Keyword(s):

Ice Sheet ◽

Greenland Ice Sheet ◽

Ellesmere Island ◽

Glacial Geology ◽

Radiocarbon Dates ◽

Previous Evidence ◽

Marine Deposits ◽

Last Glaciation ◽

Distal Side ◽

Stratigraphic Boundary

Thirty-five radiocarbon dates associated with former ice sheet margins and raised marine deposits are presented from northeastern Ellesmere Island. Along the southern margin of Hazen Plateau, and in inner Archer Fiord, a prominent morpho-stratigraphic boundary is marked by the Hazen Moraines. These moraines represent a restricted ice advance during the last glaciation and date ca. 8130 ± 200 BP. On the immediate distal side of the Hazen Moraines, eastward for 100 km towards northwestern Greenland, the majority of dates on marine limits show synchronous emergence beginning ca. 7500 BP. This zone of synchronous emergence is considered to represent an ice-free corridor isostatically unloaded between the margins of the receding Greenland and Ellesmere island ice sheets.A more widespread till, above and beyond the Hazen Moraines, extends out of Archer Fiord–Lady Franklin Bay to Robeson and Kennedy channels. This maximum ice advance is considered to predate the last glaciation on the basis of 14C and amino acid dates from ice-marginal deposits; however, alternative interpretations of the data are presented. Previous evidence suggesting an older advance of the Greenland Ice Sheet onto this coastline is confirmed. Several glaciers in the area are presently at their maximum postglacial positions.

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Some aspects of the last glaciation in the Mazury Lake District (north-eastern Poland)

Acta Palaeobotanica ◽

10.2478/acpa-2013-0001 ◽

2013 ◽

Vol 53 (1) ◽

pp. 3-8 ◽

Cited By ~ 3

Author(s):

Katarzyna Pochocka-Szwarc

Keyword(s):

Ice Sheet ◽

Late Glacial ◽

Climatic Changes ◽

Lake District ◽

Last Glaciation ◽

North Eastern ◽

Melt Water ◽

History Of ◽

Organic Sediments ◽

Late Glacial And Holocene

ABSTRACT The morphology of the Mazury Lake District (north-eastern Poland) dates from 24-19 ka (main stadial of the youngest Vistulian glaciation). During this last glacial maximum (MIS 2) a belt with lacustrine basins was formed when the ice sheet retreated at the end of the Pomeranian phase. The ice-sheet retreat is morphologically also expressed by the occurrence of end moraines. The study area is situated in the Skaliska Basin, in the northern part of the Lake District (near the Polish/ Russian border), at the periphery of zone with end moraines. Originally the basin was an ice-dammed depression filled with melt water; the water flowed out into the developing Pregoła valley when the ice retreated and did no longer dam off the depression. The basin, which is surrounded by hill-shaped moraines, is filled now with Late Glacial and Holocene glaciolacustrine sediments. The organic sediments of the basin record the history of the Late Glacial and Holocene climatic changes in this region.

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Geological evidence for changes in the East Antarctica ice sheet (60°–120°E) during the last glaciation

Polar Record ◽

10.1017/s0032247400013103 ◽

1991 ◽

Vol 27 (163) ◽

pp. 345-355 ◽

Cited By ~ 11

Author(s):

Eric A. Colhoun

Keyword(s):

Steady State ◽

Continental Shelf ◽

Ice Sheet ◽

Outer Edge ◽

East Antarctica ◽

Geological Evidence ◽

Marine Transgression ◽

Last Glaciation ◽

The Hill ◽

The Antarctic

AbstractThe East Antarctica ice sheet advanced onto the continental shelf during the last glaciation but appears to have been thinner (<300 m) than previously hypothesised and probably did not everywhere extend to the edge of the continental shelf. Where the shelf is wide, the ice probably terminated against shallow banks on its outer edge. There may not have been time for the sheet to develop the maximum profile form and thickness predicted by Hollin (1962) and Hughes and others (1981) of about 1000–500 moverthe shelf. Large outlet glaciers occupied deep troughs that conveyed most of the ice towards the edge of the shelf: intervening areas were less intensely glaciated. Much of Prince Charles Mountains and Amery Oasis were not ice-covered: Vestfold, Bunger and Casey oases were glaciated. Vestfold and Bunger oases became ice-free after 10 ka BP under the influence of the Holocene marine transgression, which was complete by about 6 ka BP. During at least the last 5–6 ka these oases have been approximately their present size. Since then the margins of the Antarctic continental ice sheet have maintained almost steady state conditions against the landward edges of the hill masses.

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Extent and dynamics of the West Antarctic Ice Sheet on the outer continental shelf of Pine Island Bay during the last glaciation

Marine Geology ◽

10.1016/j.margeo.2006.04.001 ◽

2006 ◽

Vol 230 (1-2) ◽

pp. 53-72 ◽

Cited By ~ 92

Author(s):

Jeffrey Evans ◽

Julian A. Dowdeswell ◽

Colm Ó Cofaigh ◽

Toby J. Benham ◽

John B. Anderson

Keyword(s):

Continental Shelf ◽

Ice Sheet ◽

Outer Continental Shelf ◽

The West ◽

Antarctic Ice Sheet ◽

West Antarctic Ice Sheet ◽

West Antarctic ◽

Last Glaciation

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Late-Pleistocene geomorphological and geochronological history of the former Patagonian Ice Sheet in north-eastern Patagonia (43°S)

10.5194/egusphere-egu2020-2384 ◽

2020 ◽

Author(s):

Tancrede P.M Leger ◽

Andrew S. Hein ◽

Angel Rodes ◽

Robert G. Bingham ◽

Derek Fabel

Keyword(s):

Late Pleistocene ◽

Late Quaternary ◽

Ice Sheet ◽

Glacial History ◽

Climatic Fluctuations ◽

Eastern Sector ◽

North Eastern ◽

Westerly Winds ◽

Proglacial Lake ◽

Exposure Ages

<p>The former Patagonian Ice Sheet was the most extensive Quaternary ice sheet of the southern hemisphere outside of Antarctica. Against a background of Northern Hemisphere-dominated ice volumes, it is essential to document how the Patagonian Ice Sheet and its outlet glaciers &#64258;uctuated throughout the Quaternary. This information can help us investigate the climate forcing mechanisms responsible for ice sheet &#64258;uctuations and provide insight on the causes of Quaternary glacial cycles at the southern mid-latitudes. Moreover, Patagonia is part of the only continental landmass that fully intersects the precipitation-bearing southern westerly winds and is thus uniquely positioned to study past climatic fluctuations in the southern mid-latitudes. While Patagonian palaeoglaciological investigations have increased, there remains few published studies investigating glacial deposits from the north-eastern sector of the former ice sheet, between latitudes 41&#176;S and 46&#176;S. Palaeoglaciological reconstructions from this region are required to understand the timing of late-Pleistocene glacial expansion and retreat, and to understand the causes behind potential latitudinal asynchronies in the glacial records throughout Patagonia. Here, we reconstruct the glacial history and chronology of a previously unstudied region of north-eastern Patagonia that formerly hosted the Rio Huemul and Rio Corcovado (43&#176;S, 71&#176;W) palaeo ice-lobes. We present the first detailed glacial geomorphological map of the valley enabling interpretations of the region&#8217;s late Quaternary glacial history. Moreover, we present new cosmogenic 10Be exposure ages from moraine boulders, palaeolake shoreline surface cobbles and ice-moulded bedrock. This new dataset establishes a high-resolution reconstruction of the local LGM through robust dating of five distinct moraines limits of the Rio Corcovado palaeo-glacier. Our results demonstrate that, in its north-eastern sector, the Patagonian Ice Sheet reached its last maximum extent during MIS 2, thus contrasting with the MIS 3 maxima found for the southern parts of the ice sheet. We also present geomorphological evidence along with chronological data for the formation of two ice-dammed proglacial lake phases in the valley caused by LGM ice-extent fluctuations and final glacial recession. Furthermore, this dataset allows us to determine the timing and onset of glacial termination 1 in the region. Finally, our findings include the reconstruction of a proglacial lake drainage and Atlantic/Pacific drainage reversal event caused by ice sheet break-up in western Patagonia. Such findings have significant implications for climate fluctuations at the southern mid-latitudes, former Southern Westerly Winds behaviour and interhemispheric climate linkages during and following the local LGM. They provide further evidence supporting the proposed latitudinal asynchrony in the timing of expansion of the Patagonian Ice Sheet during the last glacial cycle and enable glacio-geomorphological interpretations for the studied region.</p>

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Greenland Ice Sheet History Since the Last Glaciation

Quaternary Research ◽

10.1016/0033-5894(74)90038-6 ◽

1974 ◽

Vol 4 (4) ◽

pp. 429-440 ◽

Cited By ~ 51

Author(s):

Norman W. Ten Brink ◽

Anker Weidick

Keyword(s):

Average Rate ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Cores ◽

Large Area ◽

West Greenland ◽

Last Glaciation ◽

History Of ◽

Inland Ice

The position of the Inland Ice margin during the late Wisconsin-Würm glaciation (ca. 15,000 yr BP) is probably marked by offshore banks (submarine moraines?) in the Davis Strait. The history of the Inland Ice since the late Wisconsin-Würm can be divided into four principal phases: (1) Relatively slow retreat from the offshore banks occurred at an average rate of approximately 1 km/100 yr until ca. 10,000 yr BP (Younger Dryas?) when the Taserqat moraine system was formed by a readvance. (2) At ca. 9500 yr BP, the rate of retreat increased markedly to about 3 km/100 yr, and although nearly 100 km of retreat occurred by ca. 6500 yr BP, it was punctuated by frequent regional reexpansions of the Inland Ice that formed extensive moraine systems at ca. 8800-8700 yr BP (Avatdleq-Sarfartôq moraines), 8400-8100 yr BP (Angujârtorfik-Fjord moraines), 7300 yr BP (Umîvît moraines), and 7200-6500 yr BP (Keglen-Mt, Keglen moraines). (3) Between 6500 and 700 yr BP, discontinous ice-margin deposits and ice-disintegration features were formed during retreat, which may have continued until the ice margin was near or behind its present position by ca. 6000 yr BP. Most of the discontinuous ice-margin deposits occur within 5–10 km of the present ice margin, and may have been formed by two main phases of readvance at ca. 4800-4000 yr BP and 2500-2000 yr BP. (4) Since a readvance at ca. 700 yr BP, the Inland Ice margin has undergone several minor retreats and readvances resulting in deposition of numerous closely spaced moraines within about 3 km of the present ice margin. The young moraines are difficult to correlate regionally, but several individual moraines have the following approximate ages: A.D. 1650, 1750, and 1880–1920.Inland Ice fluctuations in West Greenland were very closely paralleled by Holocene glacial events in East Greenland and the eastern Canadian Arctic. Such similarity of glacier behavior over a large area strongly suggests that widespread climatic change was the direct cause of Holocene glacial fluctuations. Moreover, historical advances of the Inland Ice margin followed slight temperature decreases by no more than a few decades, and 18O data from Greenland ice cores show that slight temperature decreases occurred frequently throughout the Holocene. Therefore, we conclude that construction of the major Holocene moraine systems in West Greenland was caused by slight temperature decreases, which decreased rates of ablation and thereby produced practically immediate advances of the ice sheet margin, but did not necessarily affect the long-term equilibrium of the ice sheet.

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Delayed maximum and recession of an East Antarctic outlet glacier

Geology ◽

10.1130/g47297.1 ◽

2020 ◽

Vol 48 (6) ◽

pp. 630-634

Author(s):

Courtney King ◽

Brenda Hall ◽

Trevor Hillebrand ◽

John Stone

Keyword(s):

Ross Sea ◽

Ice Sheet ◽

Outlet Glacier ◽

Broad Agreement ◽

Last Glaciation ◽

Radiocarbon Data ◽

Global Sea Level ◽

The Antarctic ◽

Exposure Ages ◽

Terrestrial Data

Abstract During the last glaciation, East Antarctic outlet glaciers contributed to a grounded ice sheet in the Ross Embayment. The timing of maximum ice extent, as well as of subsequent deglaciation of these outlets, has implications for the behavior of the Antarctic Ice Sheet (AIS) and its impact on global sea level. We present 45 radiocarbon ages of lacustrine cyanobacteria from the Lake Wellman region alongside Hatherton Glacier, which are the first terrestrial data to both record advance of an Antarctic glacier to its maximum position as well as document a high-resolution chronology of subsequent retreat. Seventeen new exposure ages are widely scattered, but the youngest four are in broad agreement with the radiocarbon data. Hatherton Glacier slowly thickened from 13,000 to 9500 yr B.P. and then thinned steadily until at least ca. 2800 yr B.P. Our work affords evidence of both a delayed maximum and recession of an East Antarctic outlet glacier compared to the global Last Glacial Maximum (LGM) and supports growing evidence of a time-transgressive local LGM within the Ross Sea sector of the ice sheet. Both observations are consistent with the idea that the timing of outlet glacier expansion and timing of recession are controlled by the balance between dynamic thinning from ocean forcing and increased accumulation due to atmospheric warming.

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Climatic Conditions in the Western and Northern Cordillera During the Last Glaciation: Paleoecological Evidence

Géographie physique et Quaternaire ◽

10.7202/032879ar ◽

2007 ◽

Vol 45 (3) ◽

pp. 333-339 ◽

Cited By ~ 9

Author(s):

Rolf W. Mathewes

Keyword(s):

Plant Communities ◽

Vegetation Cover ◽

Ice Sheet ◽

Climatic Conditions ◽

Large Mammals ◽

Slow Cooling ◽

Thermal Event ◽

Last Glaciation ◽

Cordilleran Ice Sheet ◽

Tentative Correlation

ABSTRACTIn the southern Cordillera, paleoecological evidence suggests that climate was variable, from cooler than present by up to 3°C, to possibly similar to modern during the Olympia non-glacial interval (> 59 TO 25-29 ka). The development of open subalpine parkland vegetation in lowlands after 25 ka reflects slow cooling to glacial conditions. Assumptions about continuously cold and dry glacial conditions are tested and disputed. Between 18-19 ka, pollen, plant macrofossil and beetle evidence suggest relatively warm and moist conditions in the Fraser/Puget Lowlands. A tentative correlation can be inferred with the recently defined "Hanging Lake thermal event" around 18-22 ka in the unglaciated Yukon. Further work should be done to test this inference. Paleobotanical data suggest that increasing moisture, rather than increased cooling, was responsible for the late Vashon ice advance in the southwestern Cordillera. The controversy regarding the nature of the vegetation cover in eastern Beringia, north of the main Cordilleran ice sheet, is not yet settled, although evidence to date favours a complex mosaic of tundra and "steppe-tundra" plant communities supporting a greater diversity of grazing large mammals than exist in the area today.

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