270 THE LIFE OF JAMES I). FORBES. [CHAP. 



his mind all doubt as to the glacial -origin both of roches 

 moutonnees and striated surfaces. 



' I took a return car to Vernayaz, and ascended by 

 some slate quarries to the village of Sal van, on the 

 south side of the valley of the Pissevache. This is on 

 the junction of the slaty limestone (here quarried a.s 

 roofing slate), with the equivocal gneiss and granite rocks 

 of this district. I climbed a rock which immediately 

 commands the valley of the Pissevache, and also that of 

 the Rhone, which is itself extensively striated. From 

 this I had a glorious view. The ravine of the Pissevache 

 itself is magnificent, while the Rhone valley stretches 

 away 2,000 feet below. But I was most struck by the 

 stupendous wall of rock which forms the north side of 

 the Pissevache ravine, striated and polished nearly from 

 top to bottom, often in the most distinct and beautiful 

 manner. The striae are generally horizontal, but some 

 rise and fall a little, depending on the direction in which 

 the rock has offered least resistance. To talk of such 

 striae having been produced by water is ridiculous. The 

 whole valley of the Trient which is commanded from 

 this point, is composed of roches moutonnees ; and from 

 the direction of the stritB near the Pissevache, they seem 

 to be due to glaciers descending from the Tete Noire or 

 Dent du Midi, which swept round the Pissevache and 

 descended to St. Maurice ; not to a great glacier descend- 

 ing the valley of the Rhone. 



' On the shelves about Sal van are many blocks, a 

 considerable portion of which appear to have travelled. 

 Some of them, I think, are the Valorsine conglomerates. 

 These belong to the " moraines " of Agassiz and Char- 

 pentier, but this part of their theory is difficult to follow ; 

 we may admit it, as harmonizing with other evidence, 

 but scarcely as being a proof itself at least as far as 

 I have seen. . . .' 



Forbes had looked forward to meeting M. Charpen- 

 tier at Bex, but the latter had gone to Italy, so he went 

 on to Geneva. 



