Glacigenic deposits at the Edmonton Convention Centre, Edmonton, Alberta

Abstract

Four main stratigraphic units are present at the Edmonton Convention Centre site in downtown Edmonton. The lowermost sediment exposed is Cretaceous sandstone of the Horseshoe Canyon Formation. This is overlain by preglacial sands and gravels of uncertain age, which contain recumbent drag folds developed by glacial overriding of previously existing periglacial involutions. These sediments are surmounted by a glacigenic complex, consisting of subglacially modified sand and four till facies formed through passive melt out. The uppermost Quaternary sediment present is a proglacial lacustrine unit dominated by silts and clays with interbedded diamictons.A single glacial episode is recorded in the sediments. Stratigraphic relationships with other exposures throughout the Edmonton region indicate that the glacigenic complex formed during the final ice advance. Variation in the orientation of glacially induced deformations in the preglacial sands and gravels and the basal glacigenic sand indicate that the direction of ice advance was not consistent throughout the final glacial event.