History of late glacial runoff along the southwestern margin of the Laurentide Ice Sheet

1994 ◽  
Vol 13 (9-10) ◽  
pp. 859-877 ◽  
Author(s):  
Alan E. Kehew ◽  
James T. Teller
Keyword(s):  
Ice Sheet ◽  
Late Glacial ◽  
Laurentide Ice Sheet ◽  
Glacial Runoff ◽  
History Of ◽  
Southwestern Margin

Volume and Routing of Late-Glacial Runoff from the Southern Laurentide Ice Sheet

1990 ◽  
Vol 34 (1) ◽  
pp. 12-23 ◽  
Author(s):  
James T. Teller
Keyword(s):  
Gulf Of Mexico ◽  
Mississippi River ◽  
North Atlantic Ocean ◽  
Ice Sheet ◽  
Late Glacial ◽  
Laurentide Ice Sheet ◽  
Last Deglaciation ◽  
The North ◽  
Glacial Runoff ◽  
Southern Side

AbstractMelting of the Laurentide Ice Sheet during the last deglaciation added large volumes of water to many rivers and lakes of North America and to the world's oceans. The volume and routing of this meltwater not only helped shape the land's surface but also played a role in the evolution of late-glacial climate. A computerized model was prepared to quantify meltwater generation from seven drainage areas along the southern side of the Laurentide Ice Sheet at 500-yr time slices between 14,000 and 8000 yr B.P. Nearly all waters reaching the oceans flowed through the St. Lawrence, Hudson, or Mississippi River valleys. Discharge through the Mississippi River to the Gulf of Mexico during late-glacial time varied by more than a factor of 5, ranging between 17,400 m3 sec−1 (550 km3 yr−1) and 98,200 m3 sec−1 (3200 km3 yr−1). Discharge entering the North Atlantic Ocean through the St. Lawrence and Hudson valleys ranged between 20,300 m3 sec−1 (640 km3 yr−1) and 65,300 m3 sec−1 (2060 km3 yr−1), with very abrupt, twofold changes at about 11,000, 10,000, and 9500 yr B.P. as a result of the rerouting of water from the Lake Agassiz basin. As the areal extent and mass of the Laurentide Ice Sheet diminished, the total volume of meltwater plus runoff due to precipitation from its southern side declined from 3800 km3 yr−1 at about 14,000 yr B.P. to 2100 to 2600 km3 yr−1 between 11,500 and 8000 yr B.P. No meltwater entered the Gulf of Mexico after 9500 yr B.P. After the demise of the ice sheet over Hudson Bay about 8000 yr B.P., the modern continental drainage network was established and flows through the St. Lawrence declined to modern values of about 320 km3 yr−1.

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

2013 ◽  
Vol 53 (1) ◽  
pp. 3-8 ◽  
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.

Late Weichselian Environmental History in Southeastern Sweden during the Deglaciation of the Scandinavian Ice Sheet

1987 ◽  
Vol 28 (1) ◽  
pp. 1-37 ◽  
Author(s):  
Svante Björck ◽  
Per Möller
Keyword(s):  
Environmental History ◽  
Vegetation Change ◽  
Time Lag ◽  
Ice Sheet ◽  
Late Glacial ◽  
Climatic Data ◽  
Basal Ice ◽  
Tundra Vegetation ◽  
History Of ◽  
Late Weichselian

AbstractLate Weichselian litho-, bio-, and chronostratigraphy (14C and varves) in southeastern Sweden provide a detailed picture of the deglaciation pattern and dynamics, shore displacement, late-glacial sedimentation, and history of the landscape, vegetation, and climate. Two plausible glacial models were tested against lithologic, chronologic, and climatic data. Permafrost at and outside the ice margin and topographic conditions beneath the ice apparently caused inward spread of frozen glacier-bed conditions. This led to a buildup of a large zone of debris-rich basal ice. A climatic amelioration about 12,700 yr B.P. changed the temperature profile in the ice sheet. Deposition of basal melt-out till began at the previously frozen glacier bed, and a rapid recession of the clean ice set in; thin exposed debris-rich basal ice which was separated from the active ice margin about 150 yr later. In this zone of stagnant ice there followed a 200– 300-yr period marked by subglacial and supraglacial melt-out and resedimentation, forming a large hummocky/transverse moraine. The mild climate favored rapid plant immigration, and a park-tundra was established. The gradual closing of the landscape was interrupted by a 100- to 150-yr period of tundra vegetation and a cool, dry climate, with local vegetational differences caused by differences in soil moisture. About 12,000 yr B.P. a second climatic amelioration set in, and during the next 1000 yr a birch (and pine) woodland gradually developed. Soils stabilized and Empetrum heaths became abundant as the climate gradually deteriorated at the end of this period. By 11,000 yr B.P. the area had become a tundra again with scattered birch stands, dominated by herbs such as Artemisia, Chenopodiaceae, grasses, and sedges. Some 500 yr later a birch/pine woodland again succeeded, and within about 500 yr the vegetation changed to a rather closed woodland as the climate ameliorated further. However, the time lag between climatic and vegetation change was considerable.

Late Deglaciation of the Central Labrador Coast and Its Implications for the Age of Glacial Lakes Naskaupi and McLean and for Prehistory

1990 ◽  
Vol 34 (3) ◽  
pp. 296-305 ◽  
Author(s):  
Peter U. Clark ◽  
William W. Fitzhugh
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Late Glacial ◽  
Time Frame ◽  
Laurentide Ice Sheet ◽  
Glacial Lakes ◽  
Central Coast ◽  
Relative Sea Level ◽  
Level Curves

AbstractThe age of the marine limit and associated deglaciation has been estimated from relative sea-level curves for the Hopedale and Nain areas of the central Labrador coast as approximately 7600 ± 200 and 8500 ± 200 yr ago, respectively. These ages indicate that the ice margin remained on the coast for up to 3000 yr longer than previously estimated. Because the central coast is due east of glacial lakes Naskaupi and McLean, the earliest the lakes could have formed was <8500 ± 200 yr ago, with their largest phases being fully established only after 7600 ± 200 yr ago. This suggests that the age of the lakes, and associated deglaciation of the central Labrador-Ungava region, is younger by at least 1500 yr than previously estimated. A late-glacial marine-based ice mass in Ungava Bay that dammed the lakes collapsed ca. 7000 yr ago. Within this time frame, therefore, the glacial lakes only existed for <500 yr. The persistence of the Laurentide Ice Sheet margin on the central Labrador coast until 7600 yr ago probably restricted the northward movement of early prehistoric people into northern Labrador.

scholarly journals Configuration and Dynamics of the Laurentide Ice Sheet During the Late Wisconsin Maximum

2007 ◽  
Vol 36 (1-2) ◽  
pp. 5-14 ◽  
Author(s):  
Arthur S. Dyke ◽  
Lynda A. Dredge ◽  
Jean-Serge Vincent
Keyword(s):  
Ice Sheet ◽  
Gravity Anomalies ◽  
Late Glacial ◽  
Laurentide Ice Sheet ◽  
Geological Evidence ◽  
Original Proposal ◽  
Field Evidence ◽  
Free Air ◽  
Free Air Gravity ◽  
Basin Region

ABSTRACT Prior to 1943 the Laurentide Ice Sheet was considered to have three major domes centered in Keewatin, Labrador, and Patricia (TYRRELL, 1898 a, b; 1913). FLINT (1943) argued that these centres were of only local and temporary importance and favoured a single-domed ice sheet. Despite the lack of supporting geological evidence, and despite the proposition of a Foxe Dome in the interim (IVES and ANDREWS, 1963), the single-dome concept was not seriously challenged until the late 1970's and, in fact, is still strenuously supported (HUGHES era/., 1977 ; DENTON and HUGHES, 1981). This paper extends and modifies recent conclusions that the Laurentide Ice Sheet had more than one dome at the Late Wisconsin maximum. We propose a model incorporating five domes (M'Clintock, Foxe, Labrador, Hudson, and (?) Caribou) based on the position of ice divides, ice flow patterns, drift composition, late-glacial features, postglacial isostatic recovery and free-air gravity anomalies. Our Labrador and Hudson domes closely correspond to Tyrrell's Labradorean and Patrician ice sheets; our Caribou and M'Clintock domes together with the Franklin Ice Complex over the Queen Elizabeth Islands north of the Laurentide Ice Sheet, correspond to Tyrrell's original Keewatin Ice Sheet. The style of glaciation of the Foxe Basin region was not known to Tyrrell, but our reconstruction of the Foxe Dome is in close agreement with the original proposal of Ives and Andrews. Like Tyrrell, our reconstruction is based on field evidence obtained through extensive mapping; the single dome model continues to be unsupported by geological data.

scholarly journals Glacial and Sea Level History of Lowther and Griffith Islands, Northwest Territories: A Hint of Tectonics

2007 ◽  
Vol 47 (2) ◽  
pp. 133-145 ◽  
Author(s):  
Arthur S. Dyke
Keyword(s):  
Northwest Territories ◽  
Sea Level ◽  
Ice Sheet ◽  
Canadian Arctic ◽  
Laurentide Ice Sheet ◽  
Structural Elements ◽  
Ice Flow ◽  
Ice Load ◽  
Last Glaciation ◽  
History Of

ABSTRACT Lowther and Griffith islands, in the centre of Parry Channel, were overrun by the Laurentide Ice Sheet early in the last glaciation. Northeastward Laurentide ice flow persisted across at least Lowther Island until early Holocene déglaciation. Well constrained postglacial emergence curves for the islands confirm a southward dip of raised shorelines, contrary to the dip expected from the ice load configuration. This and previously reported incongruities may indicate regionally extensive tectonic complications of postglacial rebound aligned with major structural elements in the central Canadian Arctic Islands.

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