Complex sentence: It separates the Rocky Mountains on its east from the Columbia Mountains and the Cassiar Mountains on its west, as well as skirts part of the McGregor Plateau area of the Nechako Plateau subarea of the Interior Plateau of British Columbia.
Split into simpler sentences: It separates the Rocky Mountains on its east from the Columbia Mountains and the Cassiar Mountains on its west. It also skirts part of the McGregor Plateau area of the Nechako Plateau subarea of the Interior Plateau of British Columbia.