On the Ice-worn Rocks of Scotland

Abstract

§ 1. AT the bottom of all the Drift-beds there is in our northern latitudes a phenomenon which, if rightly understood, would dispel much of the obscurity that still envelopes the history of that period; I mean that curious scoring and polishing of the rocky bed on which the Drift is found so frequently reposing. Saussure, in his Alpine journeys, had often remarked those rounded masses which he called roches moutonn~es, and also did not omit to note the polishing of the rocky surface ; curiously enough, however, although so familiar with glaciers, he did not refer these appearances to their true cause, but attributed this scoring of the rocks to the passage over them of boulders hurried along by a rush of water. Colonel Imrie, also, and Sir James Hall, who in 1812 both described the same appearances in Scotland, sought to explain them in a similar manner. As this theory of their origin has found favour with several geologists, I am induced to describe here a ease of some interest which came under my notice, and was peculiarly fitted to test the sufficiency of a powerful torrent, carrying with it great boulders and stony debris, to affect the rocks in the manner under consideration. § 2. In the county of Argyle an artificial channel was cut, a good many years ago, between the Sound of Jura and Loch Fyne, called the Crinan Canal ; it is about 9 miles long, and lies in an E. and W. direction