The Canadian Rockies are quite different in appearance and geology from the American Rockies to the south of them. The Canadian Rockies are composed of layered sedimentary rock such as limestone and shale, whereas the American Rockies are made mostly of metamorphic and igneous rock such as gneiss and granite. The Canadian Rockies are overall more jagged than the American Rockies, because the Canadian Rockies have been more heavily glaciated, resulting in sharply pointed mountains separated by wide, U-shaped valleys gauged by glaciers, whereas the American Rockies are overall more rounded, with river-carved V-shaped valleys between them. The Canadian Rockies are cooler and wetter, giving them moister soil, bigger rivers, and more glaciers. The tree line is much lower in the Canadian Rockies than in the American Rockies. https://en.wikipedia.org/wiki/Canadian_Rockies