The formation continues to the north with gigantic peaks such as An Teallach near Ullapool, and Stac Pollaidh in Sutherland. The Torridonian rocks continue south to Applecross opposite Skye, where similar massive mountains occur. The Black Cuillin are mainly composed of basalt and gabbro; the latter is a very rough rock which makes for superb grip for mountaineers. It is from the dark colour of the gabbro that the Black Cuillin receive their name. The summits of the Cuillin are bare rock, jagged in outline and with steep cliffs and deep cut corries and gullies.