220 ICE ITS FORMS AND FUNCTIONS. 



transparent state of the glacier or ice-river. In its primary 

 stage it is technically known as neve or ice-snow; and this 

 neve", which stands intermediate between the pure unsunned 

 snow of the winter heights and the moving glacier, is re- 

 garded as the fond or fountain of all true glaciers. Ever fed 

 by new snowfalls from above, it is gradually pushed down- 

 wards by the force of gravitation, and in turn propels the 

 glacier, whose own weight and partial mobility also assist 

 the downward movement. The whole is, in fact, one great 

 motion, just as it is part of the great circulation by which 

 the water of the ocean is disseminated through the air and 

 over the land, and the water of the land returned once 

 more to the ocean. Acquiring volume and weight as it 

 descends (and some of the Alpine glaciers are from 80 to 

 600 feet in thickness), the glacier grinds and smoothes the 

 rocks over which it passes ; and this it does by the earth, 

 gravel, and rock-debris which become incorporated with its 

 mass, and which act like so many rasps and chisels on the 

 rocky surface. Slow in its motion, but persistent and irre- 

 sistible, its course is ever downwards, and marked by abra- 

 sion, rounding, smoothing, and striation of the subjacent 

 rocks. And as it descends, the blocks and debris, loosened 

 by the frost from the adjacent cliffs, fall on its surface, and 

 are borne along in long winding spits, till the mass finally 

 melts away in the lower valleys, and then this rock-debris 

 is left in mounds or moraines. These moraines some of 

 which are lateral, or on the sides ; some medial, or in the 

 middle ; and some terminal, or at the melting end bear 

 ample testimony of the destruction that has taken place 

 among the rocks above, and yet it is but a small portion 

 of what has been discharged as impalpable mud by the dis- 

 coloured stream that issues from the glacier. 



Wherever glaciers occur and they can only occur in 

 mountains above the snow-line, and in regions where there 



