The author proceeded to shew that the lake theory of the Lochaber shelves was not inconsistent with any established geological truths, but was on the contrary supported by them.

He alluded to the occurrence in the Lochaber district, as well as in other parts of Scotland, in valleys far from the sea, not only of lakes at high level, but of beach lines on hill-sides precisely analogous to those of Glen Roy, and shewing depressions of water to nearly the same extent. One of the localities referred to is a valley near Inverournan, where three parallel roads are to be seen shewing a depression first, of about 197 feet, secondly, of 94 feet, and lastly, of 184 feet. The blockage required for this ancient lake, and of which a small remnant still exists, was nearly as extensive as that required for Glen Roy.