Surficial geology, Canim Lake, British Columbia

Abstract

The Canim Lake map area (92P/15) straddles the contact of three physiographic region of south-central British Columbia: the Fraser Plateau to the west, the Shuswap Highland southeast of Canim Lake and south of Canim River and the Quesnel Highland northeast of the Canim Lake. The Fraser Plateau is a region of rolling topography with an average elevation of approximately 1200 m above sea level. The highlands represent uplifted and dissected plateaus. Most of the region drains to the east through Canim River which empties in Mahood Lake. This system is part of the North Thompson River drainage. The region is predominantly underlain by till which consists of a poorly sorted diamicton with clasts of all size. Bedrock outcrops are rare and limited in extent. In some of the valleys, till is overlain by glaciofluvial sediments which were deposited in meltwater streams at the end of the last glaciation. In places, till has been completely eroded by meltwater erosion. Glaciolacustrine sediments, deposited in glacial lakes which formed at the end of the last glaciation, were mapped in the Bridge Creek and Canim Lake valleys. Lacustrine sediments are present at the periphery of modern lakes throughout the map area. These were deposited at a time when the lakes occupied a higher level. Modern streams sediments (alluvium) are present in extent large enough to be mapped in some of the valleys. Colluvial deposits are mapped on steep slopes throughout the map area. Four large landslides have been mapped in the region: in the Canim River and Hendrix Creek valleys, two kilometres south of Hawkins Lake, and one kilometre southeast of McNeil Lake along the map boundary. During the last glaciation, probably at glacial maximum, ice was dominantly moving to the south southwest as recorded by flutings, crag-and-tails, drumlins, and striations. Only west of Roger Lake was the ice moving to the south southeast. However, an earlier phase of ice flow to the west is recorded in the northwest sector of the map area in the region of Boomerang Lake. During deglaciation, the eastward drainage through Canim River was dammed and a glacial lake developed in that valley and its tributaries.