1855.] 



SHARPE — ELEVATION OF THE ALPS. 



105 



The contrast between the rounded and the rugged portions of the 

 mountains is best seen in the gneiss, where its foliation dips at a high 

 angle. Among the stratified rocks, there is often a difficulty of di- 

 stinguishing the flat surfaces of the beds from those produced by 

 subsequent abrasion. 



The accompanying woodcuts (figs. 1 and 2), taken from drawings 

 which Mr. Ruskin has had the kindness to lend me, will illustrate 

 this feature in the form of the Swiss mountains better than any de- 

 scription ; and they show us also that it attracts the notice of the 

 artist as well as of the geologist. The first drawing (fig. 1) is a view 



Fig. 1. — The Chain of Mont Blanc, as seen from the Valley of 



Chamounix. 



E, E, indicate the line of erosion. 



of the Chain of Mont Blanc looking up the valley of Chamounix. In 

 this view the definite level at which the rugged peaks all rise from 

 the lower rounded shoulders of the chain is well seen, that level 

 being at about 9000 feet above the sea. The second (fig. 2) is a 

 drawing of the Matterhorn, or Mont Cervin, taken from the Rifi*elberg, 

 in which the same contrast is most strongly marked. I have not ascer- 

 tained the exact height of the base of the Matterhorn, which is above 



worn away large portions of their sides. Prof. Forhes, on the contrary, though 

 alluding hypothetically to glaciers, really describes the erosion which I ascribe to 

 the waves of the sea. 



It will be remarked that M. Agassiz notices two lines of erosion at different 

 levels in different parts of the Alps. 



The contrast between the rugged peaks of the Alpine mountains and the rounded 

 shoulders from which they rise, had previously attracted the attention of M. Hugi, 

 who accounts for it by dividing granite into two mineral classes, — 1st, true granite, 

 which forms rounded masses ; and 2ndly, halb-granit, which forms rugged peaks 

 ('Alpenreise,' p. 55) ; but he gives no mineralogical distinction between the 

 rocks, and no subsequent observers have been able to detect a difference between 

 them. The change of outline between the upper and lower parts of the same 

 mountains is shown in Hugi's plates 8, 9, 12, and 13. 



