390 'Remarks on Glaciers. 



sel, around which all the granite is deeply striated. They 

 likewise appear throughout the whole valley of Hash, particu- 

 larly on the beautiful rounded surfaces of the Helle-Platte, he- 

 low Handeck. M. Braun, an engineer, has noticed them at 

 Leissingen, on the left bank of the lake of Thun ; M. A. Guyot, 

 at Oberwald, in the upper Valais. The whole of the lower 

 Valais is, in like manner, the bed of a glacier, of which the 

 lateral moraines maybe distinguished at a pretty considerable 

 height above the valley. I have taken care to indicate these 

 on the map (that of Keller) as I have determined them from 

 Martigny to Lausanne. Polished surfaces, striae, and all the 

 phenomena produced by the action of ice, appear more beau- 

 tiful and distinct on the Jura range than in any other place, 

 accompanied likewise with Alpine blocks disposed in two zones, 

 one above the other, the second rising to a point upwards of 

 2000 feet above the level of the plain. The identity of these 

 polished surfaces and striae with those observed among the cal- 

 careous rocks of the Alps — ^for example, below the glacier of 

 Rosenlaui in the Bernese Oberland, — the distribution of rol- 

 led blocks on the sides of this chain, and their I'elations to the 

 Alpine moraines, leave no doubt as to the former existence of 

 a layer of ice which covered all the great Swiss valley, and 

 moved towards the north-east, in the direction of the dechvity. 

 This icy covering would be no doubt circumstanced somewhat 

 differently from a glacier enclosed within a narrow Alpine val- 

 ley, but the principal characters, notwithstanding, must have 

 been the same. 



From the whole of these phenomena, and the circumstance 

 of analogous striag having been observed in Sweden by M. 

 Sefstroem, I conclude, that at a certain epoch the whole of 

 Europe was covered with ice : that this epoch marks the date 

 of the disappeai'ance of the large mammifera which have been 

 discovered among the ice of northern regions ; that it must 

 have preceded the elevation of the Alps ; but that the rece- 

 dence of the ice, the polished surfaces, the moraines, and the 

 dispersion of the boulders to the very summits of high moun- 

 tains, must all have been posterior to the elevation of the 

 Alps to their present level. 



