Page:Geological Evidences of the Antiquity of Man.djvu/323

Rh Neufchatel in company with M. Desor, the country round Soleure with Mr. Langen, the southern side of the great strath near Lausanne with M. Morlot, the basin of the Aar, around Berne, with M. Escher von der Linth; and having satisfied myself that all the facts which I saw north of the Alps were in accordance with M. Guyot's views, I crossed to the Italian side of the great chain, and became convinced that the same theory was equally applicable to the ancient moraines of the plains of the Po.

M. Escher pointed out to me at Trogen in Appenzel, on the left bank of the Rhine, fragments of a rock of a peculiar mineralogical character, commonly called the granite of Pontelyas, the natural position of which is well known near Trons, a hundred miles from Trogen, on the left bank of the Rhine, about thirty miles from the source of that river. All the blocks of this peculiar granite keep to the left bank, even where the valley turns almost at right angles to its former course near Mayenfeld below Chur, making a sharp bend, resembling that of the valley of the Rhone at Martigny. The granite blocks, where they are traced to the low country, still keep to the left side of the Lake of Constance. That they should not have crossed over to the opposite river-bank below Chur is quite inexplicable, if, rejecting the aid of land-ice, we appeal to floating ice as the transporting power.

In M. Morlot's map, already cited, we behold between the areas occupied by the glacial drift of the Rhine and Rhone three smaller yet not inconsiderable spaces, distinguished by distinct colours, indicating the peculiar detritus brought down by the three great rivers, the Aar, Reuss, and Limmat. The ancient glacier of the first of these, the Aar, has traversed the lakes of Brienz and Thun, and has borne angular, polished and striated blocks of limestone and other rocks as far as Berne, and somewhat below that city. The Reuss has also