Located on the Continental Divide in the upper Buchanan Creek Valley, 4.5 km southwest of Cecilia Lake. Park, Major headwater Fraser River.
Latitude 53; 54; 15 Longitude 120; 04; 00, Topo map 93H/16
Named by Interprovincial Boundary Survey in 1923. The name refers to the impregnable aspect of the feature; an extremely steep shale slope or wall extends almost 3 miles from this feature to Bastille Mountain - "a great wall of rock shaped like a cantilever span." Official name.