Cuillin in colour, particularly in the shade, but when in sunlight the Black Cuillin can appear grey to brown in colour. The main ridge forms a narrow crest, with steep cliffs and scree slopes. The ridge is about 14 km long (measured from Gars-behinn in the south to Sgùrr nan Gillean in the northeast), and curves in an irregular semi-circle around Loch Coruisk, which lies at the heart of the range. The highest point of the Cuillin, and of the Isle of Skye, is Sgùrr Alasdair in the Black Cuillin at 992 m (3,255 ft). The Red Cuillin are mainly composed
Rùm Torridonian sandstone and shales resting on Lewisian gneiss. Two of the Cuillin are classified as Corbetts: Askival and Ainshval, (Old Norse for "mountain of the ash trees" and "hill of the strongholds" respectively) and Rùm is the smallest Scottish island to have a summit above . Other hills include Hallival, Trollaval ('mountain of the trolls'), Barkeval, and Sgurr nan Gillean (Gaelic: "peak of the young men") in the Cuillin and Ard Nev, Orval, Sròn an t-Saighdeir and Bloodstone Hill in the west. It is likely that only the higher peaks remained above the Pleistocene ice sheets as nunataks. Hallival and