Rocky Mountain Trench

a system of narrow meridional depressions occupied by the valleys of the Pelly, Kechika, Finlay, Parsnip, Fräser, and Columbia rivers in the Canadian Cordilleras. It is associated with an abyssal fault that separates the Rocky Mountains from the belt of the Interior Plains. The Rocky Mountain Trench is about 2,000 km long, with a relative depth of 1,000–1,500 m. The valley slopes were formed by reverse over-thrust faults, along which Precambrian rocks overlie Lower Paleozoic rocks.