Map 253

Map 253

MAP 253

Drift Thickness of Peerless Lake Area, Alberta (NTS 84B)

Author(s) Pawlowicz, J.G. Fenton, M.M. Date 2005-10-17

The drift thickness map of the Peerless Lake area (NTS 84B) shows the variation in thickness of unconsolidated sediment lying between the bedrock surface and the present-day land surface, and complements the Drift Thickness of Alberta map. The thickness of the drift varies from locally less than 2 metres in Buffalo Head Hills to over 200 metres in the Loon River Lowland in the central part of the map area. Thick drift fills the major paleovalleys, which are the Muskwa Valley, the Red Earth Valley and Gods Valley. The drift is thinnest on the Peerless Lake Upland, the Utikuma Uplands and the Buffalo Head Hills Upland. In general the areas of thin drift correspond to areas where the bedrock topography is high. Exceptions are the hills composed of thick drift, such as the ones located south of Muskwa Lake and southwest of Peerless Lake. These features are likely hill-hole pairs produced by glaciotectonism with lakes occupying the source depressions (holes). The drift also thickens in the southwestern part of the Utikuma Uplands. Experience from more detailed investigations in eastern Alberta have shown that unmapped, narrow, deep drift-filled channels are to be expected.