The Rocky Mountain Trench is a long and deep valley extending approximately 1,500 km from the Bitterroot Valley in northwest Montana through British Columbia to the Liard Plain just south of the Yukon Territory. Its predominantly flat floor is 3–20 km wide and ranges in elevation between 600 m and 1,000 m above sea level. With walls made of sedimentary, volcanic and igneous rock, the Trench is sometimes referred to as the “Valley of a Thousand Peaks” because of the towering mountain ranges on either side: the Rocky Mountains to the east and the Columbia, Omineca and Cassiar mountains to the west. Humans have relied on the rich resources provided by this distinctive landscape from pre-colonial times to the present.
A continental divide is a ridge or natural boundary of elevated terrain that separates the drainage basins of a continent. Each drainage basin contributes its water to river systems, which in turn flow into distinct larger bodies of water, such as oceans. The main continental divide in Canada follows the ridge of the Rocky Mountains.