CGRG Bibliography of Canadian Geomorphology
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Author : Duk-Rodkin, A.; Lemmen, D. S.; and Klassen, R.W.
Date : 1998
Title : Interactions of Laurentide and Cordilleran Ice during the Late Wisconsinan
Publication : 1998 Annual Meeting, Geological Society of America, Toronto, October 26-29. Abstracts with Program.
Issue :
Page(s) :
Abstract
The eastern slopes of the Cordillera, from southern Alberta to northern Yukon, record over large areas coalesence of the Laurentide and Cordilleran ice sheets (LIS and CIS, respectively) during the Late Wisconsinan. Research over the past decade has refuted previous models of an ice-free corridor for this interval, but questions of timing, dynamics and synchroniety of activity remain. In the northern Cordillera the LIS attained its last glacial maximum (LGM) ca. 30 ka BP, and was in retreat when contacted by valley glaciers advancing out of the Cordillera ca. 22 ka BP. Numerous sections document multiple montane tills recording several glaciations, capped by a single continental till demonstrating that the LIS reached this region only during the Late Wisconsinan. In the southern Cordillera the LIS did not attain its LGM until The highest Shield erratics are found in the foothills of SW Alberta at 1615 m asl, seemingly incongruous with other observations. Although tectonics may be invoked to explain these anomalously high elevations, it is extremely unlikely that >ca. 300 m of differential uplift has occurred along the foothills in the past 14 ka. Therefore these erratics may be evidence of pre-Late Wisconsinan continental glaciation of this region. Additional evidence suggesting multiple continental glaciations is the distribution of distinctive 'Manitoba' carbonates through southern Alberta, an occurrence that cannot readily be accounted for by Late Wisconsinan ice dynamics as presently reconstructed.
Bibliography of Canadian Geomorphology