Round the head of Loch Torridon, an arm of the sea which penetrates for more than ten miles into the mountains of West Ross, are grouped the bare and rugged peaks of the Torridon, Coulin, and Ben Damph forests, most of which reach or exceed a height of 3000 feet above sea-level, Leagach, the highest, rising 3400 feet directly from the water’s edge. These ranges may be described as forming roughly a triangle, of which the head of the loch is the apex, Leagach and Beinn na h’ Eaglaise are respectively the northern and southern sides, while the base is represented by the western front of the hills known collectively as the ‶Grey Heads,″ and individually as Sgurr Dubh, Beinn Liath Mhor, Sgurr Ruadh, and Meall a’ Chinn Deirg. They are composed for the most part of red and purple grits and sandstones, lately proved to be of pre-Cambrian age, and to which the name of Torridonian has been given, from this region, in which they are most characteristically developed. Outliers of Cambrian Quartzite also occur, either capping the highest peaks, or in lenticular and wedge-shaped masses repeated by thrusts at various horizons in the Torridonian. This triangular area is intersected by two main valleys—Glen Torridon and the valley of the Amhainn Thraill—which converge at a point three-quarters of a mile from the head of the loch. Glen Torridon is straight, narrow, and trench-like, with rocky precipitous sides, and—except at the head—no tributary glens. Glen Thraill is wider, especially in