CGRG Bibliography of Canadian Geomorphology
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Author : Clague, J.J.; and Menounos, B.
Date : 2005.
Title : The last days of the Cordilleran Ice Sheet.
Publication : Water, Ice, Land, And Life: The Quaternary Interface. Canadian Quaternary Association 2005 Conference June 5-8, 2005, University of Manitoba, Winnipeg, Manitoba.
Issue : Abstract Volume:
Page(s) : A16.
Abstract
Recent field studies have provided a clearer picture of the pattern and timing of disappearance of the last Cordilleran ice sheet. The ice sheet attained its maximum size 17,500 cal yr BP, but abrupt warming during the Bølling interval (~16,000-14,000 cal yr BP) caused snowline to rise, triggering top-down wasting and rapid frontal retreat. Retreat of the ice sheet across the continental shelf of western British Columbia was particularly rapid, due in part to sea-level rise. By 15,000 cal yr BP, the British Columbia continental shelf was ice-free and the large southern lobes of the ice sheet (Puget, Okanagan, Pond Oreille) terminated north of the International Boundary. The ice sheet continued to decay late in the Pleistocene as solar insolation increased, transforming the Cordillera into a mosaic of active and stagnant glaciers, ice-free ground, and ice-dammed lakes. Climatic deterioration during the Older Dryas and Younger Dryas chronozones slowed the decay. The southern margin of the ice sheet in Fraser Lowland east of Vancouver and in Howe Sound north of Vancouver advanced several times between 14,000 and 12,000 cal yr BP, and similar advances occurred at the western margin of the ice sheet near Terrace. By 11,000 cal yr BP, the Cordilleran ice sheet was dead, and most glaciers in western Canada were no more extensive than they are today. The plateaus of central and northern British Columbia were probably freed of ice later than plateaus to the south. Active glaciers persisted in high mountain valleys in British Columbia and Yukon until the end of the Pleistocene, after plateaus had become ice-free. Alpine glaciers responded to Younger Dryas cooling, but the lowering of snowline at that time was too small to trigger resurgence of remnant ice masses on the plateaus. Considerable north-south asymmetry is evident in the response of glaciers in high mountains to Younger Dryas cooling. Cirque and valley glaciers in the Omineca and Cassiar Mountains in northern British Columbia advanced up to 10 km from cirques onto or against stagnant ice in trunk valleys. In contrast, cirque glaciers in the southern Rocky Mountains advanced no more than 1 km from contemporary glacier margins during the Younger Dryas.
Bibliography of Canadian Geomorphology