M. Agassiz on Glaciers, Moraines, and Erratic BlocTcs. 869 



low the direction of the slope of the mountain ; on the contrary, 

 like the gibbosities, these furrows are oblique and longitudinal, 

 a direction which excludes every idea of a stream of water be- 

 ing the cause of these erosions. Another curious fact, which 

 is quite inconsistent with the action of water as their cause, 

 is, that these polished surfaces are uniform, even where the 

 rock is composed of fragments of different degrees of hardness, 

 and the shells which it contains are sliced as in an artificially 

 polished slab of marble. We likewise remark, upon the sur- 

 faces which are at all fresh, a number of fine lines or scratches, 

 similar to those produced by a diamond on glass, and which 

 in general follow the direction of the oblique furrows. 



The localities in which these appearances may most readily be 

 perceived in the environs of Neuchatel, are the Mail, on the side 

 of the lake, at the surface of the Neocomian formation, and at 

 the Plan, at the spot where the old road joins the new one. The 

 most remarkable, however, are at some distance from the town, 

 as, for example, above Landeron, on the surface of the Port- 

 land rock, at the confines of the vineyard and the forest, in 

 the neighbourhood of Saint-Aubin and above Concise. 



In some localities great excavations may be observed, and 

 even something very like walls, which could only have been 

 produced by the cascades which descend, between the fissures 

 of the ice. To any one who has examined in the Alps the 

 bottoms of the ancient glaciers, it appears manifest that it 

 is the ice which has produced these polished surfaces, as, for 

 example, those in the valley of the Rhone, to which we have 

 above alluded. It is worthy of remark, that these surfaces are 

 never found at tlie bottoms of the small longitudinal valleys 

 which are formed by the abrupt faces of the different zones of 

 beds which compose our chains, nor even upon the escarpment 

 of those of such mural walls as look towards the mountain, 

 whilst I have noticed them on many steeps which look towards 

 the Alps, as, for example, along the new road between Saint- 

 Aubin and the Castle of Vauxmarcus. 



It is of no less importance to point out the differences which 

 exist between these laves and the other polished surfaces with 

 which they may be confounded, but which resemble them only 

 in a few particulars. I allude to the polished surfaces which 



