TWO GLACIAL PERIODS. 193 



latter moraine spread over the Jorat, and also deposited great 

 masses of rock at Lausanne (on Montbenon), at Morges, 

 at Aubonne, &c., and consequently had a different direc- 

 tion from that of the first period. The same deviation may 

 be noticed in the central moraines, which extended over the 

 present position of the lake of Geneva, and probably deposited 

 great masses of debris and rocks in the bottom of the lake during 

 the subsequent retreat of the glacier. The intermediate moraines 

 running near the sides became afterwards lateral moraines. 

 Thus at the time of the first glacial dispersion the blocks of the 

 Val Ferret undoubtedly formed a central moraine which extended 

 as far as the Jura. But as the glacier subsequently became 

 smaller, and at the same time its level was lowered, this moraine 

 came nearer to the edges, and was deposited at 400 feet above 

 the bottom of the valley of Monthey for a distance of five 

 miles in the form of a rampart from 500 to 800 feet thick, in 

 which many blocks lay one upon the other in the most singular 

 positions, such as are only seen among rocky debris at the 

 lateral moraines of Swiss glaciers. 



It is further worthy of notice that the moraines of the first 

 period chiefly contain rocks from the highest mountain-masses, 

 and that the moraines of the second period comprise fragments 

 from lower regions from which it has been inferred that in the 

 former period the fields of granular snow reached higher up the 

 mountains, and that only the topmost peaks projected above 

 them. This circumstance, as well as the direction which the 

 moraines follow, show that in the first period there was a greater 

 extension of the glaciers. 



The glacier of the Aar filled up the valleys of the Bernese 

 Oberland, and smoothed the walls of rock up to a height of 

 2000 feet above the present valley-bottom. It covered the 

 basins of the lakes of Brienz and Thun, and stretched over the 

 ground to the north of Thun. Its northern boundary was near 

 Berthoud, where its further advance was prevented by the glacier 

 of the Rhone. 



The glacier of the Reuss united with glaciers from the valleys 

 of the Canton of Uri, the Engelberg, and the Muottathal. The 

 main glacier came from Uri;* at the Righi -and the Hochfluh it 

 must have been divided into two branches, of which the left made 



VOL. n. o 



