Morphologic and stratigraphic evidence for Allerød and Younger Dryas age glacier fluctuations of the Cordilleran Ice Sheet, British Columbia, Canada and Northwest Washington, U.S.A. |
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| Authors: | DORI J KOVANEN |
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| Institution: | (e-mail: ), University of British Columbia, Department of Earth and Ocean Sciences, Vancouver, B.C., Canada V6T 1Z4 |
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| Abstract: | The late Wisconsin deglaciation of the Fraser Lowland is reconstructed by integrating surficial mapping, stratigraphic, palynological, oceanographic (from previous studies), radiocarbon, and shaded digital topographic data. Moraines associated with glacier fluctuations along the southwestern margin of the Cordilleran Ice Sheet are recognized for the first time and their chronology is established from 70 radiocarbon dates secured by morphologic and stratigraphic evidence. Following emergence of the lowland at c. 11.6 14 C kyr BP, three periods of glacier readvance occurred 11.6-11.4 and 10.9-10.2 14 C kyr BP during the Sumas interval. The spatial and temporal relationships of Sumas Drift indicate four recognizable phases, which unifies and extends the surficial geology across the U.S.-Canadian border. |
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