CGRG Bibliography of Canadian Geomorphology
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Author : Dixon-Warren, A.B.; and Hickin, A.S.
Date : 2000.
Title : Evidence for a Late Wisconsinan ice divide in the Cassiar Mountains, northwestern British Columbia.
Publication : 2000 GSA Annual Meeting -- Reno, Nevada
Issue :
Page(s) :
Abstract
A reconnaissance Quaternary mapping project was undertaken to improve the understanding of Late Wisconsinan stratigraphy and the directions of paleo ice-flow movement in the Swift River area, northwestern British Columbia. Surficial mapping revealed a single till unit deposited during the Fraser Glaciation, the last advance of the Cordilleran Ice Sheet. The chronology and direction of ice-flow patterns were inferred from the orient tion of macro-scale landforms, striae, grooves and pebble fabrics. The presence of rounded arêtes and overridden cirques in the study area suggest ice may have built-up from the growth of cirque and valley glaciers in the Cassiar Mountains. Valley glaciers advanced and coalesced to form an extensive ice sheet at the glacial maximum. The positions of erratics at elevations exceeding 2000 metres above mean sea level signify that glacial ice covered the entire study area. The paleo ice-flow data suggest an ice divide over the Cassiar Mountains where ice flowed westward from the divide into the Teslin Depression and streamed northwestward into the Yukon while on the east side of the mountains, ice flowed northeast then onto the Liard Plateau and then into the Yukon. Whether the movement of the Cordilleran Ice Sheet was influenced at all times by the underlying topography or if ice flowed independently across the topography remains unclear. However, as the ice thinned during deglaciation, flow directions altered increasingly in accordance with topographic control. Lateral and recessional moraines and ice marginal meltwater channels define the location of ice pauses in the valleys during local glacier retreat. A set of older striae and bedrock stoss and lee forms, not previously documented, were recorded along the shores of Teslin Lake and the Swift River valley. These features suggest an earlier flow in the region that was northeasterly.
Bibliography of Canadian Geomorphology