CGRG Bibliography of Canadian Geomorphology
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Author : Fisher, T.G.; and Smith, D.G.
Date : 1994.
Title : Glacial Lake Agassiz : its northwest outlet and paleoflood, 9900 BP
Publication : Western Division Canadian Association of Geographers Annual Meeting, University College of the Cariboo, Friday, March 11 and Saturday, March 12, 1994, Kamloops, B.C.
Issue :
Page(s) : 9.
Abstract
Valley morphology and sediment in the Fort McMurray region of Alberta, indicates that a catastrophic flood down the lower Clearwater and Athabasca River valleys 9900 BP. Bars and lower Clearwater and Athabasca River valleys 9900 BP. Bars and erosional remnants on alternate sides of the upper scoured benchlands, indicate laterally extensive erosion before the incision and formation of a straight inner spillway channel. Evidence that glacial Lake Agassiz (Emerson Phase) was the water source consists of: 1) strandlines from the head of the spillway (between 495-438 m asl) which extend southeastwards over a distance of 400 km to south of Lac La Ronge, Saskatchewan; 2) glaciolacustrine sediments at a minimum of 470 m asl (40 m higher than previously reported); 3) sedimentary evidence for a regional, short-lived transgression (e.g. cobble clasts overlying sand-dunes); and, 4) 11 radiocarbon ages from the Emerson Phase at 9896 B.P., chronologicallysimilar with the average of 6 radiocarbon ages from spillway flood and deltaic deposits at 9869 B.P. Moraine morphology, sedimentology and elevation, in association with glaciolacustrine sediments suggest that glacial Lake Agassiz was in close proximity to much of the Cree Lake Moraine when the northwest outlet first opened. The outlet opened by overtopping and subsequent incision of a drainage divide (morainal, possibly ice-cored) located 30 km east of the Alberta-Saskatchewan border, lowering glacial Lake Agassiz 57 m to a stable elevation of 438 m asl in the Lake Wasekamio area. Paleohydrological reconstructions using derivations of Manning's equation, indicate a peak discharge range from 3.7 - 5.5 x 1,000,000 cu m/sec. We propose that water from glacial Lake Agassiz entered the Arctic Ocean via glacial Lake McConnell and the Mackenzie River rather than the Gulf of Mexico via the Mississippi River, as previously thought. The additional influx offreshwater from the flood (16,000 cu km) and 400 years of annual flow (total 198,000 cu km) into the Arctic at the close of the ice age, may have had an abrupt, major influence on northern climate and ecosystems.
Bibliography of Canadian Geomorphology