Map 215

Map 215

MAP 215

Drift thickness of the Edmonton map area

Author(s) Andriashek, L.D. Date 2005-10-17

Drift thickness in the Edmonton map area ranges from less than 10 m over flat-lying bedrock surfaces, to more than 70 m within the Cooking Lake Moraine and a number of buried valleys. Extensive areas of thin drift are found in much of the east third of the map areas, as well as within the northwest corner. Thin drift is also found in the southwest part of the map area where Glacial Lake Edmonton drained and eroded some of the existing drift cover. Extensive areas of thick drift (greater than 50 m) are found as infill of major preglacial valleys, particularly the Beverly, Onoway and Stony valleys and headwaters of the Vegreville and Whitford valleys. Stratified drift in excess of 80 m thickness is also present along the flanks of the buried Sturgeon Valley. Thick drift, mainly till, is found within the Cooking Lake Moraine where glacial thrusting eroded Cretaceous sediment along the contact of the Horseshoe Canyon and Bearpaw/Belly River formations. Glacial thrusting and deposition of material from the Vegreville Valley beneath Beaverhill Lake, likely accounts for the thick drift sequence located southwest of the lake in Tp 50, Rg 20.