Late Quaternary glacial history of Lake Hazen Basin and eastern Hazen Plateau, northern Ellesmere Island, Nunavut, Canada

1999 ◽  
Vol 36 (9) ◽  
pp. 1547-1565 ◽  
Author(s):  
I Rod Smith
Keyword(s):  
Late Quaternary ◽  
Ellesmere Island ◽  
Glacial History ◽  
Glacial Geomorphology ◽  
Ice Caps ◽  
Proglacial Lakes ◽  
History Of ◽  
Ice Retreat ◽  
The Last Glacial Maximum ◽  
The Last Glacial

The glacial history of the broad interior of northeastern Ellesmere Island is first documented here. Studies of glacial geomorphology and marine and lacustrine sedimentology indicate that the region was inundated by cold-based ice emanating from the Grant Land Mountains sector of the Innuitian Ice Sheet during the last glacial maximum. Retreat of coalescent, marine-based Ellesmere and Greenland ice from Robeson Channel had started by 10.1 ka BP and reached the mouths of many fiords along southeast Hazen Plateau by 8 ka BP. Proglacial meltwater channels emanating from plateau ice caps, crosscut lateral meltwater channels marking the retreat of Grant Land Mountain ice. The crosscutting is interpreted to reflect an early Holocene growth of plateau ice caps concurrent with the retreat of marine-based margins. This suggests that initial regional ice retreat was eustatically controlled. Stabilization of glacier margins at the heads of fiords occurred by 7.5-7 ka BP, after which land-based margins retreated as little as 10 km by 6 ka BP. Across much of northeastern Hazen Plateau, however, Grant Land Mountain ice retreated more rapidly. This more rapid retreat was accentuated by the impoundment of proglacial lakes against the plateau to the south and the subsequent breakup of ice by calving. Glaciers continued to occupy much of Lake Hazen Basin at 5.3 ka BP, after which they broke up rapidly in a proto-Lake Hazen, retreating to margins at, or behind, those of the present by 5 ka BP.

scholarly journals The glacial and sea-level history of Darling Peninsula, eastern Ellesmere Island

2002 ◽  
Vol 52 (3) ◽  
pp. 349-359 ◽  
Author(s):  
Lyn Gualtieri
Keyword(s):  
Sea Level ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Ellesmere Island ◽  
Glacial History ◽  
Last Glacial ◽  
History Of ◽  
Raised Beaches ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract The glacial history of Darling Peninsula is recorded by meltwater channels and lateral moraines deposited by local ice that extended seaward of the present coast during the last glacial maximum. Above these moraines, shelly till and erratics of both Greenland and Ellesmere Island prove nance record more extensive ice of unknown age. At the time of this more extensive ice cover, Ellesmere Island ice displaced Greenland ice from many parts of this coastline, as shown by the widespread absence of Greenland erratics and shelly tills above Holocene marine limit. The chronology of deglaciation is based on 14 C dates obtained on marine shells collected from either ice-contact deltas or raised beaches close to marine limit (79-88 m asl). Deglaciation began at least 7.5 ka BP and the distribution of ice on the peninsula was similar to present conditions by 6.0 ka BP. The reconstruction of the sea level history of Darling Peninsula contributes to the reconstruction of regional isobases drawn on 7.5 ka BP shorelines which locally reach 80-90 m asl.

scholarly journals Morphology and late Cenozoic (<5 Ma) glacial history of the area between David and Mawson Glaciers, Victoria Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 55-60
Author(s):  
Anja L.L.M. Verbers ◽  
Volkmar Damm
Keyword(s):  
Ice Sheet ◽  
Field Work ◽  
Topographic Map ◽  
Glacial History ◽  
Ice Surface ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
History Of ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Glacio-geological field work and radar ice-thickness sounding were carried out in the area between David and Mawson Glaciers. A subglacial topographic map has been compiled from radio-echo-sounding data. The northern part of this map shows that the trench of David Glacier reaches a depth of more than 1000 m below sea level. The area south of David Glacier comprises a landscape of nunatak clusters dissected by glaciated valleys with ice thicknesses as much as 800 m. Subglacial cirques occur at the outer margins of the nunatak clusters. A model for the regional glacial history is proposed. It starts with a major deglaciation in the Pliocene, which results in marine transgression in basins west of the Transantarctic Mountains. During the late Pliocene, the ice advanced towards the northeast, depositing a thin layer of (Sirius Group) till containing reworked mid-Pliocene marine diatoms. Due to accelerated mountain uplift, the ice cut iIlto the pre-Pliocene peneplain, eroding broad valleys. A period of ice-sheet retreat followed to expose a landscape of large nunataks separated by wide valleys. During this period, local cirque glaciation occurred. When the ice sheet advanced again, another phase of uplift forced the glaciers to cut deeper into the valleys. Probably since the Last Glacial Maximum the ice surface has lowered by about 100 m.

scholarly journals Morphology and late Cenozoic (<5 Ma) glacial history of the area between David and Mawson Glaciers, Victoria Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 55-60
Author(s):  
Anja L.L.M. Verbers ◽  
Volkmar Damm
Keyword(s):  
Ice Sheet ◽  
Field Work ◽  
Topographic Map ◽  
Glacial History ◽  
Ice Surface ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
History Of ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Glacio-geological field work and radar ice-thickness sounding were carried out in the area between David and Mawson Glaciers. A subglacial topographic map has been compiled from radio-echo-sounding data. The northern part of this map shows that the trench of David Glacier reaches a depth of more than 1000 m below sea level. The area south of David Glacier comprises a landscape of nunatak clusters dissected by glaciated valleys with ice thicknesses as much as 800 m. Subglacial cirques occur at the outer margins of the nunatak clusters. A model for the regional glacial history is proposed. It starts with a major deglaciation in the Pliocene, which results in marine transgression in basins west of the Transantarctic Mountains. During the late Pliocene, the ice advanced towards the northeast, depositing a thin layer of (Sirius Group) till containing reworked mid-Pliocene marine diatoms. Due to accelerated mountain uplift, the ice cut iIlto the pre-Pliocene peneplain, eroding broad valleys. A period of ice-sheet retreat followed to expose a landscape of large nunataks separated by wide valleys. During this period, local cirque glaciation occurred. When the ice sheet advanced again, another phase of uplift forced the glaciers to cut deeper into the valleys. Probably since the Last Glacial Maximum the ice surface has lowered by about 100 m.

scholarly journals Underwater faunal assemblages: radiocarbon dates and late Quaternary vertebrates from Cold Lake, Alberta and Saskatchewan, Canada

2018 ◽  
Vol 55 (3) ◽  
pp. 283-294
Author(s):  
Christopher N. Jass ◽  
Devyn Caldwell ◽  
Christina I. Barrón-Ortiz ◽  
Alwynne B. Beaudoin ◽  
Jack Brink ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Faunal Remains ◽  
Radiocarbon Dates ◽  
East Central ◽  
Faunal Assemblages ◽  
History Of ◽  
Cold Lake ◽  
The Last Glacial Maximum ◽  
Insight Into ◽  
The Last Glacial

Late Quaternary faunal remains from three underwater settings in Cold Lake, Alberta and Saskatchewan, Canada, include at least 13 vertebrate taxa consistent with assemblages that postdate the Last Glacial Maximum (LGM). Seven new radiocarbon dates range from 10 350 ± 40 to 161 ± 23 years BP and provide insight into the post-LGM biotic history of east-central Alberta and west-central Saskatchewan. The presence of an essentially modern large mammal biota is suggested for the mid-Holocene, and possibly earlier, if the absence of extinct or extirpated taxa in association with Late Pleistocene Bison at the Alberta–Saskatchewan site is meaningful. Taphonomically, some of the remains suggest deposition in open environments during the Holocene, possibly when lake levels were lower. The recovery of late Quaternary faunal remains from a present-day lacustrine setting is novel, and suggests that similar records may occur in other lakes in western Canada, including those in areas with scarce Quaternary vertebrate records.

Late Quaternary glacial and sea-level events, Clements Markham Inlet, northern Ellesmere Island, Arctic Canada

1986 ◽  
Vol 23 (9) ◽  
pp. 1343-1355 ◽  
Author(s):  
Jan Bednarski
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Ellesmere Island ◽  
Glacial Retreat ◽  
Radiocarbon Dates ◽  
Ice Caps ◽  
Marine Deposits ◽  
Ice Retreat ◽  
Level Ice ◽  
Small Valley

Clements Markham Inlet cuts into the Grant Land Mountains of the northernmost coast of Ellesmere Island. The head of the inlet is bounded on three sides by mountain ice caps that surround lowlands mantled by extensive raised marine deposits. Fieldwork and mapping of late Quaternary sediments were used to determine the limits of past glaciations and the nature of ice retreat from the inlet head. Forty-five radiocarbon dates on driftwood and marine shells provide a deglacial chronology and document related sea-level adjustments.High-level ice-marginal meltwater channels and mountain summit erratics indicate that ice once inundated all of Clements Markham Inlet. During at least one of these undated glaciations, ice flowed unconstrained by the local topography. In contrast, the most recent glaciation involved confluent trunk glaciers, which terminated near the head of the inlet. Beyond this terminus, smaller glaciers entering the sides of the inlet debouched into a glacioisostatically depressed sea (full glacial sea). Retreat from the last glaciation is documented by moraines, kame terraces, and ice-contact deltas.Inside the ice limit at the head of the inlet, sections commonly show that a marine transgression occurred immediately after the retreat of the ice. Conversely, sections outside the last ice limit, along the sides of the inlet, show complex intercalations of marine and glacigenic sediments. These indicate proximal ice-front conditions where small valley glaciers locally contacted the sea.The oldest date on the last ice limit is 9845 BP. After this, slow retreat was in progress, and some glaciers were within 6 km of their current positions by ca. 9700 BP. At the head of the inlet, the mouths of the confluent valleys became ice free by 8000 BP. After 8000 BP, glacial retreat accelerated greatly, so that the entire lowland became ice free within 400 years.Relative sea-level curves from the inlet indicate ice-load changes that confirm this pattern of ice retreat. Outside the last ice limit, the full glacial sea reached 124 m asl by at least 10 000 BP. Emergence from this sea occurred slowly between at least 10 000 and 8000 BP (0.72 m 100 year−1). This period was followed by "normal" rapid postglacial emergence, which decelerated to the present.The marine limit of the full glacial sea rises from 92 m asl, at the outer coast, to 124 m asl near the last ice limit at the head of the inlet. Initial emergence from the full glacial sea occurred simultaneously throughout the inlet. On the proximal side of the last ice limit, the marine limit descends in the up-ice direction and becomes progressively younger. Individual strandlines tilt up in a southwesterly direction towards the central Grant Land Mountains, suggesting a former centre of glacio-isostatic loading in that area.

Radiocarbon Dates on Deglaciation, Cordillera Central, Northern Peruvian Andes

1989 ◽  
Vol 32 (1) ◽  
pp. 111-113 ◽  
Author(s):  
P.W. Birkeland ◽  
D.T. Rodbell ◽  
S.K. Short
Keyword(s):  
Late Glacial ◽  
Glacial Maximum ◽  
Radiocarbon Dates ◽  
Cordillera Central ◽  
Peruvian Andes ◽  
Relative Dating ◽  
History Of ◽  
Ice Retreat ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AbstractThree radiocarbon dates along with relative-dating criteria place limits on the deglaciation history of Manachaque Valley, Cordillera Central. Ice retreated from the late-glacial maximum by at least 12,100 yr B.P. During ice retreat numerous moraines were deposited throughout the valley. Glacier cover was reduced to about half that of the last glacial maximum by at least 9700 yr B.P. and to less than a tenth by at least 6450 yr B.P. Because all dates are minimum, the dates and field data are consistent with little or no ice remaining by early Holocene. No unambiguous Younger Dryas moraines are present.

The late Quaternary history of lodgepole and jack pines

1985 ◽  
Vol 15 (5) ◽  
pp. 749-772 ◽  
Author(s):  
William B. Critchfield
Keyword(s):  
Late Quaternary ◽  
Jack Pine ◽  
The North ◽  
Last Glaciation ◽  
Variation Patterns ◽  
History Of ◽  
Quaternary History ◽  
Fossil Records ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Lodgepole and jack pines (Pinuscontorta Dougl. ex. Loud. and Pinusbanksiana Lamb.), components of the North American boreal forest, have pioneering roles after major disturbances such as fire or glaciation. These species are closely related and hybridize in western Canada, but their fossil records and contemporary variation patterns suggest they had completely different late Quaternary histories. Several taxonomically recognized geographic races of lodgepole pine apparently survived the last glaciation without drastic modification, the northern races either persisting in far-northern refugia or migrating from the south. The uneven influence of jack pine on northern lodgepole populations implies repeated genetic contacts, but less marked introgression in the other direction could be of post-Pleistocene origin. Jack pine occupied its entire range after the last glacial maximum and lacks taxonomically recognized races. In the Great Lakes region, however, the presence of regionally distinct populations suggests the species had at least two Midwestern refugia. This hypothesis is contrary to the widely held view that jack pine occupied most or all of its range from a well-documented refugium in southeastern North America, but is supported by limited fossil evidence that pine persisted in the Midwest during the last glaciation.

Late Quaternary Vegetation and Climate of the Sahel

1989 ◽  
Vol 32 (3) ◽  
pp. 317-334 ◽  
Author(s):  
Anne-Marie Lézine
Keyword(s):  
Late Quaternary ◽  
Middle Holocene ◽  
Zonal Vegetation ◽  
Arid Conditions ◽  
Southward Shift ◽  
History Of ◽  
The Last Glacial Maximum ◽  
Vegetation And Climate ◽  
The Last Glacial ◽  
Semiarid Conditions

AbstractPollen and phytogeographic evidence provides a vegetational history of the Sahel for the period 0–18,000 yr B.P. The zonal vegetation fluctuated latitudinally and its most extreme positions occurred at 18,000 and 8500 yr B.P. The first involved a southward shift of the Sahelian wooded grassland to 10°N under the arid conditions of the last glacial maximum. The second change shows a rapid northward migration of humid vegetation: Guinean elements reach 16°N and Sahelo-Sudanian elements extend to the southern margin of the modern Sahara (21°N) when the Atlantic monsoon flux increased. In the middle Holocene the extensive spread of Sudanian elements into the modern Sahelian zone suggests the appearance of a markedly dry season. The modern Sahelian semiarid conditions appeared abruptly at 2000 yr B.P.

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