Small but spectacular Bow Falls is below the Fairmont Banff Springs, only a short walk from downtown. The waterfall is the result of a dramatic change in the course of the Bow River brought about by glaciation. At one time the river flowed north of Tunnel Mountain and out of the mountains via the valley of Lake Minnewanka. As the glaciers retreated, they left terminal moraines, forming natural dams and changing the course of the river.
Eventually the backed-up water found an outlet here between Tunnel Mountain and the northwest ridge of Mount Rundle. The falls are most spectacular in late spring when runoff from the winter snows fills every river and stream in the Bow Valley watershed.
© Andrew Hempstead, from Moon Western Canada, 3rd Edition