Bedrock Topography of the Gleichen Map-Area, Alberta

This report isolates two primary geologic divisions, bedrock and the overlying unconsolidated material, by superimposing a topographic map of the present land surface for the Gleichen map area (NTS 82I) upon a topographic map of the bedrock surface. An interpretation of the preglacial topography shows that a major preglacial drainage divide trends roughly east-west through this map area. It separates tributaries of the two major preglacial valley systems in southern Alberta, the Calgary Valley system to the north and the Lethbridge Valley system to the south. The main Calgary Valley trends across the northern part of the map area; a major tributary of the Lethbridge system, the Teepee Valley, trends across the southern part. The mainly buried alluvial gravels of these ancient valleys range up to 50 feet in thickness; the thickness of the surficial deposits ranges from a few feet up to 200 feet or more.