ALPINE SCULPTURE 265 



diminishing in magnitude as the order of the valley ascends, 

 carving the earth and carrying its materials to lower levels. 

 We find that the larger valleys have been filled for untold 

 ages by glaciers of enormous dimensions, always moving, 

 grinding down and tearing away the rocks over which they 

 passed. We have, moreover, on the plains at the foot of 

 the mountains, and in enormous quantities, the very matter 

 derived from the sculpture of the mountains themselves. 



The plains of Italy and Switzerland are cumbered by 

 the debris of the Alps. The lower, wider, and more level 

 valleys are also filled to unknown depths with the materials 

 derived from the higher ones. In the vast quantities of 

 moraine- matter which cumber many even of the higher val- 

 leys we have also suggestions as to the magnitude of the 

 erosion which has taken place. This moraine-matter, more- 

 over, can only in small part have been derived from the 

 falling of rocks upon the ancient glacier; it is in great part 

 derived from \he grinding and the plowing-out of the gla- 

 cier itself. This accounts for the magnitude of many of the 

 ancient moraines, which date from a period when almost 

 all the mountains were covered with ice and snow, and 

 when, consequently, the quantity of moraine-matter derived 

 from the naked crests cannot have been considerable. 



The erosion theory ascribes the formation of Alpine 

 valleys to the agencies here briefly referred to. It in- 

 vokes nothing but true causes. Its artificers are still there, 

 though, it may be, in diminished strength; and, if they are 

 granted sufficient time, it is demonstrable that they are com- 

 petent to produce the effects ascribed to them. And what 

 does the fracture theory offer in comparison ? From no 

 possible application of this theory, pure and simple, can 

 we obtain the slopes and forms of the mountains. Erosion 



SCIENCE V 12 



