Large-scale effects of subglacial meltwater flow in the southern Slave Province, Northwest Territories, Canada

Abstract

Broad corridors in the southern Slave Province of the Northwest Territories are marked by meltwater-scoured bedrock, irregular and transverse gravel ridges, gravel bars, crag and tail features (tails formed of gravel), drumlins, boulder lags, potholes, plunge pools, meltwater-sculpted slopes (in some cases defining till plateaus), and eskers. Most of the above features can either be attributed to the subglacial erosion of till by high-velocity, turbulent meltwater under high pressures and (or) meltwater transport and deposition of the eroded material. Potholes, plunge pools, and meltwater-sculpted slopes developed in unconsolidated deposits have received little attention in the literature, although they are the equivalent of similar features in bedrock that have had their origin attributed to subglacial meltwater erosion. In the case of inverted plunge pools, eroded materials, including boulders, have been transported upwards by meltwater some tens of metres during their formation. Features and deposits owing their origin to subglacial meltwater can lead to complex dispersal patterns of minerals and metals contained within both till and glaciofluvial deposits.