That the fragments of the basaltic plateau preserved in each member of the group of the Small Isles were once connected as a continuous volcanic plain can hardly be doubted. Indeed, as already stated, they were not improbably united with the plateau of Skye on the north, and with that of Mull, Morven and Ardnamurchan oh the south. Taking the whole space of land and sea within which the basalt of Small Isles is now confined, we may compute it at not much less than 200 square miles. In Eigg, Muck, Canna and Sanday the basalts retain their almost horizontal position, and from underneath them the Jurassic strata emerge in the first of these islands. The central part of the plateau in the island of Rum has suffered greatly from denudation. It now consists of four small outliers of basalt, which lie at levels of 1200 feet and upwards, on the western slope. The basalt is underlain by a thick mass of red Torridon Sandstone, which, with some gneisses and schists, forms the general underlying platform of this island. These rocks are doubtless a continuation of the red sandstone and schists of Sleat, in Skye, and like them have been subjected to those post-Cambrian convolutions and metamorphism whereby the Lewisian Gneiss and Torridon Sandstone have been brought above younger rocks, and have been crushed and rolled out so as to assume a new schistose arrangement. Before the time when volcanic action began, a mass of high ground, consisting of these ancient rocks, stood where the island of Rum is now situated. The streams of basalt spread around it, not only covering the surrounding low tracts of Jurassic rocks, but gradually accumulating against the hills, and thus reducing them both in area and in height above the plain.[246] Viewed from Canna the western coast of Rum presents a striking picture of the general relations of the volcanic masses of the Inner Hebrides and of the enormous denudation which they have undergone (Fig. 267). The Torridon Sandstones are there seen to mount into ranges of hills, capped with outliers of the basalt-plateau, while behind rise the great eruptive bosses of gabbro and granophyre. The edges of the sheets that form the outliers would, if prolonged, cover the northern or lower half of the island, where pre-Cambrian rocks form the surface. In the southern half, the continuity of the basalt has been partly obscured and partly destroyed by the protrusion of the great masses of gabbro that form the singularly picturesque mountain group to which this island owes its prominence as a landmark far and wide along the West Coast of Scotland.