The author first described, generally, the appearance of the loose materials covering the surface; and referred to some districts in the north of Scotland, especially the central one on the borders of Perth and Inverness shires, as demonstrating the effects of vast currents of water having passed over the surface. He also referred to the valleys of the river Conan and its tributaries, in Ross-shire, as presenting an epitome of all the phenomena which may be supposed to result from a vast flood gradually subsiding, and taking the direction of the valleys. He then shortly alluded to the theories proposed to account for the present condition of the surface, which appear to resolve themselves into the effects of a remote cause.