80 M. Ch. Martins on the 



ward, in former times, by the glacier as far as the right bank 

 of the Arve. 



Beyond Nangy, the plain comprised between the southern 

 flank of Voirons and the eastern declivity of the Saleves 

 mountains is strewed with blocks of protogine, accumulated 

 chiefly on the plateau of Bornes, situate behind these moun- 

 tains ; but it is on the eastern side of the two Saleves that 

 we must look for the terminal moraine of the glacier of the 

 Arve. Notwithstanding an active clearing which has been 

 going on for many years, the rounded shoulder of these two 

 mountains is everywhere covered with these blocks. A great 

 number of them have penetrated into the gorge of Monetier, 

 others have remained suspended on the top of the precipice 

 which looks towards Geneva, or have been precipitated into 

 the plain the centre of which is occupied by that town. Near 

 the village of Mornex, situate on the eastern slope of the 

 smaller Saleve, we likewise find polished rocks, and consi- 

 derable collections of sand, gravel, and striated pebbles. 

 Thus all the proofs of the ancient existence of a glacier are 

 united on the eastern declivity of the Saleves, as visible, as 

 indisputable, as in the valley of Chamonix, the cradle of the 

 gigantic glacier whose traces we have followed. For it, the 

 Saleves presented no insuperable barrier; it passed their 

 summits, turned round their extremities, and threw its last 

 blocks on Mount Sion, an elevation situated on the south of 

 Geneva, and the point where the waters are divided, and flow 

 to Lake Leman or to that of Annecy. Blocks of protogine 

 occupy the most elevated parts of Mount Sion, and the last 

 group crowns the summit of U hill rising above the village of 

 Vers, near the road from Geneva to Chambery. 



On two sides of Mount Sion, the geologist finds erratic 

 blocks of a very varied nature ; and, recollecting the moun- 

 tains where these rocks form considerable masses, he be- 

 comes convinced that he is at the point where three great 

 antediluvian glaciers met, — that of the Rhone, which filled 

 the whole of the Leman basin ; that of the Isere, which de- 

 bouched by the lakes of Annecy and Bourget ; and that of the 

 Arve, which, inserting itself between them like a sharp 

 wedge, came to its termination near the village of Vers. The 



