The last glaciation of west-central Ellesmere Island, Arctic Archipelago, Canada

1985 ◽  
Vol 22 (3) ◽  
pp. 347-368 ◽  
Author(s):  
D. A. Hodgson
Keyword(s):  
Late Holocene ◽  
Ice Cover ◽  
Ellesmere Island ◽  
Distal Margin ◽  
Ice Caps ◽  
Devon Island ◽  
Last Glaciation ◽  
West Central ◽  
Reliable Evidence ◽  
Middle And Late Holocene

Locally abundant ice-marginal landforms lie in a 500 km long zone with a distal margin 10–60 km west of the margins of modern ice caps on central Ellesmere Island. Much of this drift belt, at the heads of the fiords, was deposited by the oscillating margin of a coalesced predecessor of the modern ice caps between 9000 and 7000 BP. The ice continued to retreat east of the present margin, and readvanced to its modern limit in a middle and late Holocene cooler climate. Unweathered but undated till and striations at the base of the drift suggest that the belt does not mark the western limit of central Ellesmere Island ice in the last glaciation. The limit lies an unknown distance downfiord; glaciers in the fiords may have floated. No reliable evidence was found for a complete ice cover of western Ellesmere Island and Eureka Sound in the last glaciation; nevertheless much of central and southern Ellesmere Island and Devon Island may have been glaciated by a regime that left few erosional or depositional landforms. Alternatively, emergence of an unglaciated Eureka Sound, underway by 9000 BP, may have followed combined peripheral glacioisostatic depression by encircling ice caps, whereas at the drift belt emergence was less and later, controlled only by central Ellesmere Island ice.

The late Quaternary history of Greely Fiord and its tributaries, west-central Ellesmere Island

1990 ◽  
Vol 27 (2) ◽  
pp. 255-270 ◽  
Author(s):  
John England
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Sensu Stricto ◽  
Ellesmere Island ◽  
Relative Sea Level ◽  
Ice Caps ◽  
Last Glaciation ◽  
West Central ◽  
Grounding Line ◽  
Minimum Age

Moraines and meltwater channels mark the limit of the last glaciation that interfingered with the sea around the perimeter of Greely Fiord and its tributaries. The extent of this ice advance was dictated predominantly by its proximity to the sea. Consequently, the large tidewater glaciers at the fiord heads today were so constrained by calving that they advanced only 5–10 km. Similarly, grounding-line deposits from widespread plateau ice caps also terminate just below marine limit. The most extensive outlet glaciers, which advanced 20–35 km beyond present margins, are simply those that had access to the most extensive terrain above marine limit, i.e., the northwest margin of the Agassiz Ice Cap.Forty-one new 14C dates are presented. The onset of the last ice advance must predate marine shells collected from sediments overlying a former grounding line when sea level was 122 m higher than present. At this site, the lowermost shells collected from glaciomarine silts dated 38 070 ± 410 BP, whereas a surface sample 13 m above them dated 22 900 ± 190 BP. Although both dates may be minimum estimates, they are nonetheless associated with an ice margin that retreated only a few kilometres by 7850 BP, suggesting the maintenance of the glacioisostatic loading (and relative sea level) during the interim. Nearby, shells in growth position overlying bedrock confirm that relative sea level was > 83 m asl by 38 010 ± 410 BP (minimum age). These marine deposits lie outside the last ice limit and are not overlain by glacigenic sediments.Distal to the last ice limit, Greely Fiord was occupied by the full glacial sea, whose limit is marked by discontinuous beaches and wave-cut benches. The full glacial sea rises from 116 m north of Greely Fiord to a maximum elevation of 148 m bordering its south shore from which it descends to 112 m asl near the head of Cañon Fiord. Numerous 14C dates on shells collected within 8 m of marine limit show that the full glacial sea remained stable from at least 8400 to 7400 BP. Several other shell samples collected ~20 m below marine limit are much older (> 22 000 BP). The position of relative sea level between ca. 8000 and > 22 000 BP is uncertain; however, stratigraphic evidence for an intervening regression has not been found.The modest extent of the last ice limit encircling Greely Fiord, together with its occupancy by the full glacial sea, is fully compatible with the paleogeography previously reported from northeast Ellesmere Island and northwest Greenland. Furthermore, this data base provides a reinterpretation of a 500 km transect previously reported along west-central Ellesmere Island to the south and affirms that the Innuitian Ice Sheet, defined sensu stricto for the last glaciation, is supplanted by the full glacial Innuitian Sea, which penetrated the Queen Elizabeth Islands, constraining the last ice limit.

scholarly journals The Effects of Wind on δ(18O) and Accumulation Give an Inferred Record of Seasonal δ Amplitude From the Agassiz Ice Cap, Ellesmere Island, Canada

1988 ◽  
Vol 10 ◽  
pp. 34-37 ◽  
Author(s):  
D.A. Fisher ◽  
R.M. Koerner
Keyword(s):  
Flow Line ◽  
Conductivity Measurement ◽  
Ellesmere Island ◽  
Electrical Conductivity Measurement ◽  
Ice Caps ◽  
Devon Island ◽  
Ice Cap ◽  
Annual Layer ◽  
Winter Snow ◽  
Difference Series

Wind plays an important role in determining accumulation and δ(18O) on some ice caps. Three surface-to-bed cores spaced about 1 km apart have been taken on a flow line of the Agassiz Ice Cap, Ellesmere Island. The A84 core comes from the top of a local dome. The A79 core is 1200 m down the flow line, but very close to the ridge through the local dome. The A77 core is 1100m from A79 and well away from the ridge. The ridge causes wind turbulence, which removes or scours the soft winter snow from the A84 and A79 sites. No snow is scoured from the A77 site. Because of scour the retained accumulation and average δ(l8O) are different. The accumulations are 17.5, 11.5, 9.7 cm/a (ice equivalent) at A77, A79 and A84 respectively and the corresponding surface δs are –30.40, -27.90 and –27.05‰. The core records were dated by annual layer thicknesses and by identification of electrical conductivity measurement (ECM) acid peaks. With the three cores accurately aligned we examine the (δA84-δA77) and (δA84-δA79) time series. Significant variations in these difference series are interpreted as being caused by changes in the seasonal δ amplitude, which is then explained by changes in sea-ice cover. A seasonal δ amplitude series independently obtained from the Devon Island ice cap δ noise record is consistent with that from the Agassiz Ice Cap sites.

Glacial advances and stratigraphy in Otto Fiord and adjacent areas, Ellesmere Island, Northwest Territories

1995 ◽  
Vol 32 (1) ◽  
pp. 52-64 ◽  
Author(s):  
Jan Bednarski
Keyword(s):  
Amino Acid ◽  
Ellesmere Island ◽  
Late Pliocene ◽  
Ice Caps ◽  
Quaternary Glaciation ◽  
Last Glaciation ◽  
High Amino Acid ◽  
Ice Retreat ◽  
White Point

Hvitland and Svartfjeld peninsulas have been glaciated at least two or three times since the Late Pliocene. The earliest recognized glaciation is constrained by amino acid ratios on in situ pelecypods from marine sediments stratigraphically overlying till in Otto Fiord. High amino acid ratios suggest that the shells may be Pliocene and related to recently discovered Late Pliocene Hvitland beds at White Point. The same samples yielded finite radiocarbon ages in the 30.2–34.8 ka BP range, which cautions against their acceptance. A second, mid Quaternary glaciation is suggested by intermediate amino acid ratios from in situ pelecypods and shell-bearing till covering coastal uplands along Nansen Sound. During the last glaciation the peninsula was covered by coalesced ice caps, with glacial tongues descending tributary valleys and extending into the fiords. Deglaciation of a tributary valley in outer Otto Fiord proceeded before 11.6 ka BP and before 9.1 ka BP in mid Otto Fiord, but major ice margins remained at the coast until 8–8.5 ka BP. Lateral meltwater channels record systematic ice retreat up tributary valleys into the interior of the peninsulas. The highest recognized marine limits are marked by prominent deltas at least 164 m asl on western Hvitland Peninsula. The marine limit declines eastward inside Otto, Jugeborg, and Hare fiords. The highest strandlines could not be dated; however, by ~8.3 ka BP relative sea level stood at 103 m asl.

Late Quaternary glaciation and deglaciation of the Bunger Hills, Antarctica

1992 ◽  
Vol 4 (4) ◽  
pp. 435-446 ◽  
Author(s):  
Donald A. Adamson ◽  
Eric A. Colhoun
Keyword(s):  
Late Holocene ◽  
Late Quaternary ◽  
Ice Sheet ◽  
Antarctic Ice Sheet ◽  
Quaternary Glaciation ◽  
Last Glaciation ◽  
Coastal Inlets ◽  
The Antarctic ◽  
Raised Beaches ◽  
Middle And Late Holocene

The Bunger Hills were covered by the Antarctic Ice Sheet during the last glaciation. During deglaciation the ice sheet margin collapsed into the marine inlets and the sea entered the oasis before 7.7 ka BP. Raised beaches occur widely below 8.5 m and indicate uplift at 1.4 m ka−1 during the middle and late Holocene. After the coastal inlets were formed, the Edisto Ice Tongue and Apfels Glacier still impinged on land margins in the west of the oasis. Two sets of marginal moraines were formed; the Older Edisto Moraines after 6.2 ka BP and the Younger Edisto Moraines during the last few centuries. The margins of the Antarctic Ice Sheet and Apfels Glacier in the south have maintained their present positions since at least 5.6 ka BP and probably 10 ka BP.

Studies of glacial history in Arctic Canada. I. Pumice, radiocarbon dates, and differential postglacial uplift in the eastern Queen Elizabeth Islands

1970 ◽  
Vol 7 (2) ◽  
pp. 634-664 ◽  
Author(s):  
Weston Blake Jr.
Keyword(s):  
Source Area ◽  
Ellesmere Island ◽  
Northern Europe ◽  
Baffin Island ◽  
Arctic Canada ◽  
Radiocarbon Dates ◽  
Time Line ◽  
Devon Island ◽  
Last Glaciation ◽  
Raised Beaches

Dark brown pumice has been discovered recently on raised beaches of Ellesmere and Devon Islands, and in archeological sites on Baffin Island. It is similar in appearance and chemical composition to pumice associated with raised marine features throughout northern Europe, especially along the coasts of Norway and Spitsbergen. The source area for the pumice is uncertain, but Iceland is a good possibility.Radiocarbon dates on driftwood and whale bones imbedded in beaches at the "pumice level", as well as at higher and lower elevations, indicate that the pumice arrived approximately 5000 years ago.The pumice serves as a time-line and provides a means of correlating widely-separated marine features. Because these features now occur at different elevations, the amount and direction of tilt can be calculated. Also, former ice centers can be delineated, as the areas which have undergone the greatest uplift are those where the ice cover was once thickest. In Arctic Canada the "pumice level" rises westward along Jones Sound—from 16.5 m a.s.l. at the mouth of South Cape Fiord, Ellesmere Island, to 24.0 m at the eastern tip of Colin Archer Peninsula, Devon Island, ca. 130 km away. It also rises northwestward toward the head of South Cape Fiord.The Jones Sound information, plus radiocarbon dates from elsewhere in the Queen Elizabeth Islands indicating the approximate position of the shoreline at the same time, shows that there is a region in the eastern and central part of the archipelago where >25 m of uplift has occurred during the last 5000 years. This region, including considerable areas that are now sea, is believed to have been covered by a major ice sheet during the last glaciation.

scholarly journals The Effects of Wind on δ(18O) and Accumulation Give an Inferred Record of Seasonal δ Amplitude From the Agassiz Ice Cap, Ellesmere Island, Canada

1988 ◽  
Vol 10 ◽  
pp. 34-37 ◽  
Author(s):  
D.A. Fisher ◽  
R.M. Koerner
Keyword(s):  
Flow Line ◽  
Conductivity Measurement ◽  
Ellesmere Island ◽  
Electrical Conductivity Measurement ◽  
Ice Caps ◽  
Devon Island ◽  
Ice Cap ◽  
Annual Layer ◽  
Winter Snow ◽  
Difference Series

Wind plays an important role in determining accumulation and δ(18O) on some ice caps. Three surface-to-bed cores spaced about 1 km apart have been taken on a flow line of the Agassiz Ice Cap, Ellesmere Island. The A84 core comes from the top of a local dome. The A79 core is 1200 m down the flow line, but very close to the ridge through the local dome. The A77 core is 1100m from A79 and well away from the ridge. The ridge causes wind turbulence, which removes or scours the soft winter snow from the A84 and A79 sites. No snow is scoured from the A77 site. Because of scour the retained accumulation and average δ(l8O) are different. The accumulations are 17.5, 11.5, 9.7 cm/a (ice equivalent) at A77, A79 and A84 respectively and the corresponding surface δs are –30.40, -27.90 and –27.05‰. The core records were dated by annual layer thicknesses and by identification of electrical conductivity measurement (ECM) acid peaks. With the three cores accurately aligned we examine the (δA84-δA77) and (δA84-δA79) time series. Significant variations in these difference series are interpreted as being caused by changes in the seasonal δ amplitude, which is then explained by changes in sea-ice cover. A seasonal δ amplitude series independently obtained from the Devon Island ice cap δ noise record is consistent with that from the Agassiz Ice Cap sites.

Identification and significance of late Holocene tephra from Otter Creek, southern British Columbia, and localities in west-central Alberta

1977 ◽  
Vol 14 (11) ◽  
pp. 2593-2600 ◽  
Author(s):  
J. A. Westgate
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Far North ◽  
West Central ◽  
Tephra Beds ◽  
Middle Unit ◽  
Mount St Helens

Three thin, light-coloured, ash-grade tephra beds occur within the uppermost metre of peat at Otter Creek bog in southern British Columbia. The youngest tephra is related to the ~2600 year old Bridge River tephra but is probably the product of a younger and weaker eruption that directed tephra to the southeast of the vent, believed to be located in the Meager Mountain district of southwestern British Columbia. The middle unit is ~2100 years old and is tentatively correlated with one of the upper beds of set P tephra of Mount St. Helens in Washington. The lowermost tephra is equivalent to the Yn bed of set Y, derived from an eruption of Mount St. Helens about 3400 years ago.The Yn tephra has been located as far north as Entwistle in west-central Alberta but mineralogically and chemically similar tephra elsewhere in this region is ~4300 years old and thus represents an older part of the Y set. Significant compositional differences between these two extensive members of the Y set have not yet been recognized.

Human occupation strategies and related environmental-climate during the middle and late Holocene in central Pampas of Argentina

The Holocene ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 244-261 ◽  
Author(s):  
Pablo G Messineo ◽  
Marcela S Tonello ◽  
Silvina Stutz ◽  
Alfonsina Tripaldi ◽  
Nahuel Scheifler ◽  
...  
Keyword(s):  
Late Holocene ◽  
Specific Activity ◽  
Climatic Conditions ◽  
Hard Material ◽  
Human Occupation ◽  
Climate Conditions ◽  
Lithic Assemblage ◽  
Depositional Rate ◽  
Archeological Site ◽  
Middle And Late Holocene

The main objective of this work is to generate and integrate interpretations of human occupation strategies and inferences of the environmental-climatic conditions in the central Pampas during the middle and late Holocene. We present a novel archeological–geological–paleoecological analysis in the area of the Cabeza de Buey lake, placed in an aeolian landscape. During the middle Holocene, two events of human occupations were recognized at Laguna Cabeza de Buey 2 archeological site. Both events present a small amount of lithic materials, a low diversity of tools and activities developed with them (principally hard material), and the hunting and primary processing of artiodactyls. These evidences suggest a locus of specific activity associated with an ephemeral human settlement under climate conditions drier than present and the presence of small, brackish, and shallow water bodies. For the late late Holocene, the hunter-gatherer occupation has a higher depositional rate of lithic assemblage, stones with diverse origins, presence of pottery fragments, a great lithic tool diversity, knapping techniques, and activities developed with these tools (processing wood, bone, hide, non-woody plant, and soft material). These evidences reveal an occupation with a higher degree of recurrence represented by a locus of multiple activities associated with a more stable landscape, such as an environment of dunes fixed by grass vegetation, and the establishment of a permanent water body. The different environmental characteristics for the middle and late Holocene in this area promoted that human groups develop two different patterns of mobility, settlement and use of space.

The last glaciation and sea level history of Fosheim Peninsula, Ellesmere Island, Canadian High Arctic

1996 ◽  
Vol 33 (7) ◽  
pp. 1075-1086 ◽  
Author(s):  
Trevor Bell
Keyword(s):  
High Arctic ◽  
Radiocarbon Dates ◽  
The Holocene ◽  
Ice Caps ◽  
Marine Deposits ◽  
Last Glaciation ◽  
Maximum Elevation ◽  
Glacier Runoff ◽  
History Of ◽  
Ice Conditions

The last glaciation of Fosheim Peninsula is reconstructed on the basis of landform and sediment mapping and associated radiocarbon dates. Ice growth involved the expansion of cirque glaciers and accumulation on upland surfaces that are now ice free. Limited ice buildup, despite lowering of the paleoglaciation level by 700–800 m, is attributed to the hyperaridity of the region during glacial conditions. Marine deposits in formerly submerged basins beyond the ice margins are interpreted to represent (i) sedimentation caused by local ice buildup and marine transgression by 10.6 ka BP, (ii) increased ablation and glacier runoff [Formula: see text]9.5 ka BP, and (iii) marine regression during the Holocene. Holocene marine limit reaches a maximum elevation of approximately 150 m asl along northern Eureka Sound and Greely Fiord and descends southeastwards to 139–142 m asl near the Sawtooth Mountains. A synchronous marine limit is implied where the last ice limit was inland of the sea. The magnitude and pattern of Holocene emergence cannot be fully explained by the glacioisostatic effects of the small ice load during the last glaciation of the region. Deglaciation of the peninsula was underway by 9.5 ka BP; however, local ice caps may have persisted through the wannest period of the Holocene until 6–5 ka BP. This was likely a function of reduced sea ice conditions and increased moisture availability which benefited low-lying coastal icefields, but had negligible effect on interior highland ice caps.

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