321 M. Guyot oti the 



summit itself, so that tliey seem to be without a point of at- 

 tachment. 



To these details, M. Guyot has added others respecting 

 the bottom of the valleys of Torrent and Zinal, which, when 

 united, form the deep valley of Anniviers. He points out 

 many corrections to be made in the topography and nomen- 

 clature of the peaks of these I'egions, as given by Frobel. He 

 describes the appearance of the upper valley of Tourteniagne 

 and the glaciers of Weisshorn, which occupy the bottom ; 

 then, passing the difficult and elevated Col of Joung, he 

 ascends the valley of St Nicolas and Zermatt, again examin- 

 ing the glaciers and rocks, traverses that of Saas, where he 

 determines the precise situation of the euphotides, and en- 

 ters by the Monte Moro, in the Piedmontese valley of Macug- 

 naga. From this point, traversing the Turlo, he successively 

 went through all the southern valleys of Mont Rosa, which 

 he examined particularly, with a view to the erratic forma- 

 tion, and the rocks which they furnisli. 



The valley of Aoste appeai'ed to him of the highest inte- 

 rest in this point of view. 



From the height of the Col de Joux or of Amai, by whieli 

 M. Guyot entered this large and beautiful valley, the eye 

 takes in the greater part of its extent at a single glance. 

 From this view, we may conceive beforehand the part that 

 must have been performed during the period of extensive ice, 

 by this vast reservoir, comprised between the massive heights 

 of the Pennine Alps, the elevated and compound chain of the 

 mountains of Cogne, having at its head the chain of Mont 

 Blanc, by which the view is arrested in front, at the horizon. 

 Tills presentiment is speedily confirmed. On descending the 

 Col towards the baths of St Vincent, we already perceive 

 considerable masses of erratic formation, blocks and pebbles 

 of serpentine and chlorite, mingled with glacial mud. These 

 masses, suspended on the torn and abrupt flanks of the moun- 

 tain at more than 1500 feet above the valley, indicate the 

 pressure, at another era, as well as the thickness of the an- 

 cient glaciers. Farther down, in the region of the vines, the 

 blocks become more frequent and of larger size. 



From St Vincent, as far as Ivree, there is scarcely any 



