Mountains and hills of Scotland near Ullapool and Stac Polly 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 being 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. The mountains exhibit many notable individual peaks and many exceed 1,000 metres (3,280 ft) in height, so qualifying
Geology of Skye Part of the magma chambers for the volcanoes are exposed at the surface as major intrusions of gabbro and granite. These coarse-grained igneous rocks are relatively resistant to erosion and now form the Cuillin hills. The Black Cuillin are formed of gabbro, which erodes to form the characteristically jagged outlines, although this is in large part due to the many minor intrusions, such as dykes and cone sheets that cut the gabbro. The Red Hills are formed of granite and have a more rounded topography. All pre-Quaternary rock types on the island are affected by a major swarm of dykes,