CGRG Bibliography of Canadian Geomorphology
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Author : Karrow, P.F.; Anderson, T.W.; Delorme, L.D.; Miller, B.B.; and Chapman, L.J.
Date : 1994
Title : Glacial Lake Algonquin biota, radiocarbon dates, and paleoenvironmental near Clarksburg, Ontario
Publication : NWRI Contribution
Issue : 94-120
Page(s) :
Abstract
Excavation below the Lake Algonquin gravel beach bar near Clarksburg, Ontario exposed mollusc-bearing clay over a lens of plant debris. This is the northernmost and most deeply buried Lake Algonquin fossil site thus far found in Ontario. Two radiocarbon dates of about 11 200 years confirm the age of transgressing Lake Algonquin. Plant macrofossils (21 taxa), pollen (39 taxa), molluscs (12 taxa), and ostracodes (18 taxa) indicate that the climate was colder than present and the forest-tundra ecotone was nearby initially but retreated northward rather quickly. Upward increases in abundances of molluscs and ostracodes suggest it was a time of rapid migration and colonization of species. Pond and lake sediments deposited 11 200 year B.P. have been found to have had a rich plant and animal life. The life forms indicate that Lake Algonquin water levels fluctuated substantially such that a large lagoon existed behind beach sands and gravels. These sediments were subsequently buried when the lake levels rose. The benthic ostracodes indicate that there was a tundra environment at the time. The mean annual temperature at Clarksburg, Ontario was -8%C compared to 2%C today and annual precipitation of 360 to 495 mm compared to 1088 mm today.
Bibliography of Canadian Geomorphology