CGRG Bibliography of Canadian Geomorphology
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Author : Clark, P.U.
Date : 1984
Title : Glacial geology of the Kangalaksiorvik-Abloviak region, northern Labrador, Canada
Publication : Unpublished Ph.D. dissertation. University of Colorado at Boulder
Issue :
Page(s) : 240 p
Abstract
A middle or early Wisconsinan advance of the Laurentide Ice Sheet deposited a regional drift sheet in the Torngat Mountains, Labrador. Weathering characteristics developed in drift suggest this Iron Strand drift sheet is equivalent to the Koroksoak weathering zone. Radiocarbon dates suggest a minimum age for this event of 32,200 years BP, and amino acid ratios suggest an age no older than 100,000 years BP. Amino acid ratios suggest a duration for this event <10,000 years. The ice sheet advanced 25-30 km onto Saglek Bak, Labrador Shelf, where an extensive submarine moraine system has been mapped. A late Wisconsinan advance of the Laurentide Ice Sheet is recorded by a regional drift sheet (Two Loon drift). Limits of Two Loon drift are defined by moraines and weathering breaks observed in drift. Morphological and weathering characteristics suggest this drift is correlative to the Saglek weathering zone. The maximum late Wisconsinan ice sheet was reconstructed in the Torngat Mountains from moraines marking the limit of Two Loon drift. Calculated basal shear stresses < 0.5 bar are interpreted to reflect significant movement by basal sliding. As it entered the Torngat Mountains, the Laurentide Ice Sheet became confined to major through-valleys and fiords, leaving substantial areas of northern Labrador ice-free. Ice terminated at the mouths of fiords, and thus did not advance onto the adjacent continental shelf. North of Kangalaksiorvik Fiord, the ice sheet thinned towards the northeast, whereas south of Kangalaksiorvik Fiord, contours on the ice surface became parallel to the coastline. Radiocarbon dates provide only minimum ages for deglaciation, and suggest ice retreat began 8700 - 9000 years BP. Ice had retreated west of the drainage divide by 8200 years BP. Local ice caps and cirque glaciers occupying plateau surfaces and cirque basins deposited Coleman drift during the late Wisconsinan. Snowline depression indicated by lateral moraines and cirque floor altitudes was 150-200 m below present snowline. Minor expansions of cirque glaciers occurred during the Holocene.
Bibliography of Canadian Geomorphology