CHAP. xv. DUE TO TERRESTRIAL GLACIERS. 303 



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 Ehine, fragments of a rock of a peculiar 

 mineralogical character, commonly called the granite of Pon- 

 telyas, the natural position of which is well known near 

 Trons, a hundred miles from Trogen, on the left bank of the 

 Ehine, 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 Ehone 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 Ehine and Ehone 

 three smaller yet not inconsiderable spaces, distinguished by 

 distinct colours, indicating the peculiar detritus brought down 

 by the three great rivers, the Aar, Eeuss, 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 Eeuss has also 



