CGRG Bibliography of Canadian Geomorphology
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Author : Fisher, T.G.
Date : 1998
Title : An analysis of Glacial Lake Calgary sediments to determine the Lake's Age, Cochrane, Alberta, Canada
Publication : 1998 Annual Meeting, Geological Society of America, Toronto, October 26-29. Abstracts with Program.
Issue :
Page(s) :
Abstract
Stratigraphic and sedimentologic field data in the Cochrane, Alberta area, indicate that glacial Lake Calgary is between 11.4 and 13.9 ka in age. Much of the controversy surrounding the lakes age has involved distinguishing the Calgary Formation (CF) glaciolacustrine sediments from other lake or pond sediments; and the Bighill Creek Formation (BCF) gravel from fan gravel associated with Lake Calgary or younger valley-side fans. Observations from a 200 m long exposure of BCF overlying CF in the middle of the Bow Valley indicate that the CF is older than the BCF. Calgary Formation lacustrine sediments consist of up to 87% sand, and the continuous, conformable contact with underlying till, indicates that Lake Calgary formed in a re-entrant as the Bow Valley Glacier receded from the Cordilleran/Laurentide ice complex. The lake sediment is characterized by rhythmic sediment that records continuous and high rates of sedimentation throughout the lake basin. The high sedimentation rates and lack of pollen or organic material in the valley bottom lake sediment suggests that the lake is coeval with initial deglaciation in the area (approximately 13.5 ka). Imbricate sandstone boulders on terraces incised into the Bighill delta at Cochrane indicate a large flood entered the lake via the Bighill Creek channel, truncated deltaic deposits, scoured the sandstone bedrock, formed a boulder lag and likely caused the lake level to be lowered.
Bibliography of Canadian Geomorphology