Surficial geology, southeastern portion of the Prince George map area British Columbia

Abstract

The surficial geology of the southeastern portion of the Prince George map area provides a record of the late Quaternary history of central British Columbia near the centre of the former Cordilleran Ice Sheet. The map depicts a variety of sediment units of glacial and non-glacial origin superposed on a hillshade derived from a Digital Elevation Model (DEM). From oldest to youngest, the units are bedrock, till, glaciofluvial deposits, glaciolacustrine deposits, colluvium, alluvium, and organic deposits. Till, the most aerially extensive deposit, was deposited by glacier ice and consists of boulder- to pebble-sized clasts in a matrix of sand, silt, and clay. Till underlies north-trending drumlins that indicate ice flow to the north. Glaciofluvial deposits consist of stratified, well-sorted to poorly-sorted sand and gravel. They are associated with eskers, terraces, and blankets. Some glaciofluvial deposits are kettled. Glaciolacustrine deposits comprise sand, silt, and clay deposited in a former glacial lake impounded by decaying ice masses. Colluvium is derived mainly from glaciolacustrine deposits that failed along river banks. Alluvium consists of fine silt, sand, and minor gravel deposited along modern streams after deglaciation. Organic deposits include peat and organic-rich mud that have accumulated in poorly drained depressions formed in older sediments and bedrock.