GENERAL PHENOMENA OF ALPINE GLACIERS. 239 



Darwin. Sir James Clark Ross, in his antarctic voyage, has 

 described and represented by admirable views the stupendous 

 icy barriers which fringe the coast of the inhospitable southern 

 continent. 



After reviewing the descriptions of glaciers in all regions of 

 the world, we recur to those of the Alps as presenting all the 

 characteristic features of glaciers in perfect development, and 

 under circumstances the most convenient for study. 



General Phenomena of Alpine Glaciers. The manner in 

 which a glacier protrudes itself into a valley, far below the level 

 of perpetual snow, has been already mentioned. The inference 

 being obvious, that since it is continually melting (during sum- 

 mer) in all its parts, yet retains its general form and place, the 

 waste below must be supplied by the continual advance of the 

 glacier forwards and downwards, we shall consider in the mean- 

 time the motion of the glacier as an established fact to which 

 we shall afterwards devote a separate and special discussion. 

 It very frequently happens that the termination of the greater 

 glaciers takes place in an alluvial flat in the bottom of a large 

 alpine valley (as in the glaciers of the Mer de Glace, Brenva, 

 Rhone, Lower Aar, and those of Grindelwald). From a vault 

 in the green-blue ice, more or less perfectly formed each summer, 

 the torrent issues, which represents the natural drainage of the 

 valley, derived partly from land-springs, partly from the fusion 

 of the ice. That of the Arveiron, near Chamouni, is perhaps 

 the best known, but almost every glacier possesses such a vault. 



Most usually the glacier terminates amidst a wilderness of 

 stones borne down upon its surface and deposited by its fusion. 

 Sometimes these blocks are heaped up in mounds called moraines, 

 which, when in front of the lower end of a glacier, are called 

 its terminal moraines, and mark in a characteristic and certain 

 manner the greatest limit of extension which the glacier has at 

 any one time attained. Sometimes a glacier is seen to have 

 withdrawn very far within its old limits, leaving a prodigious 

 barren waste of stones in advance of it, which, being devoid of 

 soil, nourishes not one blade of grass. At other times the 



