The rocks of Raasay have attracted a good deal of attention from geologists, despite the fact that no house of public entertainment exists on the island. That portion of it which lies to the south of Brochel Castle, exhibits a base of Torridon Sandstone, above which there may be traced, more or less completely, in two faulted areas, an ascending series from the New Red rocks to the Great Oolite group. The Jurassic strata are finely exhibited in the eastern cliffs, but westwards they are largely covered by volcanic rocks, and especially by great sheets of Granophyre which descend in that direction to the sea-level. To the south-west there is a mass of Gabbro; in other parts there are sills and countless dykes of Basalt, while the summit of Dun Caan is formed of a bedded mass of that material. Coverings of Peat, of Boulder-Clay and Gravel, serve to add variety to the geology, and to obscure the outcrops of the Jurassic and other rocks.