Should the geologist desire to extend his researches along the western coast and among the islands, he will experience an additional interest, arising chiefly from the numerous junctions of the different formations or sets of rocks which the constant erosion of the Atlantic has everywhere exposed to view. Gigantic isolated portions of granite or syenite, bared all around, are to be seen on every headland. The twistings and flexures of gneiss and the schists are frequent and remarkable. Columnar basalt, similar to Staffa, fringes the base of every islet and promontory; and from appearances like these, he will invariably infer the presence of the carboniferous deposits, which, in small detached patches are of common occurrence. Here, likewise, are to be found the lias and oolites, in marginal stripes on several of the islands, easily distinguished by their characteristic fossils, and giving unequivocal indications of a far greater extension, and continuity with the main land, ere the inroads of the sea had broken up and parted so much of the aboriginal structure of the district. The _vi et sæpe cadendo_ of geological agency—the convulsions of subterranean forces, and the destroying powers of water—are exhibited in all their grandeur, where, in the face of cliffs exposed to their foundations, the hardest rocks may be observed yielding to every wave, and the whole inner machinery of granitic and basaltic dykes which upheaved them from their basis traced in their most varying forms and complicity. Out of the Ægean a finer group of islands is nowhere to be threaded—some scarcely raised above sea-level—some towering into the clouds, as in the lofty peaks of Mull, Jura, and Rum, with an altitude almost equal to their length—most of them glorying in names soft and euphonious as the choicest of classic Greece—and yet, all fragmentary and disrupted, as if but yesterday shivered by the thunder cloud. Skye exhibits an epitome not of the islands only, but nearly of our whole British geology, in which there is every variety of trap, combined with the primary series—coal, white sandstone, and limestone—the lias and oolites of secondary formation—and mountains 3,300 feet in height, composed of Labrador feldspar and hypersthene, whose crystals in the dark composite mass rival in structure, if not in beauty, the stalactitic concretions of the Spar Cave itself. Rocks, too, are here, of metamorphic texture, to which a Macculloch did not venture to assign a name or position in his list. And the serrated jagged pinnacles of the Coolin ridge, with the black Coruisk inclosed as in a crater, who will attempt to describe—unlike to everything else in bleak, naked, precipitous grandeur! The poet of the Isles has sketched the picture—