Glaciers. 365 



whether at the sides or in the middle of a glacier, are 

 termed moraines, and at length all this material that 

 has not fallen into crevasses floats on, and is finally 

 slowly shot into the valley at the end of the ice-stream, 

 frequently forming large mounds, known as terminal 

 moraines. 



All glacier ice, even in the depth of winter in Arctic 

 regions, is said to be at a temperature of about 32 

 Fahr. that is to say, just about the melting point, ex- 

 cepting near the surface, as far as the cold atmospheric 

 temperature can penetrate. This, it is said, is rarely 

 more than eight or ten feet. Therefore, it is a common 

 statement that, beneath every glacier, water is constantly 

 flowing, caused by the melting of the ice below all the 

 year round, and also by the summer heat on the surface 

 of the glacier, and in some cases, to a less degree, by 

 springs that rise in the rocks below the ice. 1 In parts 

 of some glaciers where crevasses are not numerous, we 

 frequently find large temporary brooks, which generally 

 disappear with the frost at night ; but in all the glaciers 

 that I have seen, long before we reach their lower end, 

 all the surface water has found its way to the bottom of 

 the ice. 



The water that runs from the end of a glacier very 

 often emerges from an ice-cavern as a ready-made muddy 

 river, charged with the flour of rocks, produced in great 

 part by the grinding power of the glacier moving over 

 its rocky floor, and this river carries away the moraine 



1 I am, however, informed by Mr. James Eccles that in the mid- 

 winter of 1875 when he was in the Valley of Chamouni no water 

 flowed from the end of the well-known Glacier de Bossons, and 

 that at the lower end of the large glacier of the Mer de Glace 

 (Glacier des Bois) the stream which is large in summer had 

 decreased to a tiny rivulet. The subject requires more systematic 

 investigation both in the Alps and Greenland. 



