FIELDS OF GRANULAR SNOW. 185 



tends along the Alps of Friburg into the neighbourhood of Fri- 

 burg and Guggisberg. They are also found in the vicinity of 

 Lausanne and on the plateaus near Yverdon. 



It may naturally be asked, How have such enormous masses 

 of rock come into these regions ? what sort of force was it that 

 transported such immense blocks to a distance of fifty or sixty 

 Swiss miles ? The solution of .this problem for a long time oc- 

 cupied the attention of Swiss geologists ; and various suggestions 

 were made. 



A satisfactory explanation of the mode of transport of these 

 Alpine debris has been given by the careful investigation of the 

 glaciers of Switzerland, and of the rock-masses which are de- 

 posited on their surface and are either borne along upon them 

 or accumulated at their edges. 



To understand the transport of debris on Swiss glaciers, let a 

 person place himself on one of the gigantic Swiss mountains, 

 where, even in the summer, he will be surrounded by boundless 

 masses of snow, which fill up every hollow. On the sides of the 

 mountain and in the ravines these great fields of granular snow 

 descend and become converted into glaciers. The name of neve 

 (or firri) is given to the frozen and more or less granular snow, 

 and that of glacier to the snow which has been converted into 

 ice by being thawed and then again frozen. When the mountain 

 is high, and the fields of granular snow (or ne*ve*) are extensive, 

 the glaciers usually descend low into the valley. Most of the 

 Swiss glaciers terminate at elevations of between ] 100 and 2300 

 metres (or from 1203 to 2515 yards). The lower Grindelwald 

 glacier descends to 1039 metres (or 1136 yards) above the level 

 of the sea. In many instances the lower extremity of a glacier 

 comes down to the region of cornfields and orchard trees, where 

 from spring to autumn it must decrease by the melting of its ice. 



The glacier would therefore be constantly retiring, if its mate- 

 rials were not continually replaced by the advance downwards 

 of the mass of the glacier. The enormous masses of snow accu- 

 mulated in the fields of neve on the cold summits of Swiss moun- 

 tains are constantly being carried down to lower regions and 

 converted into water. Brooks take their source from the melted 

 ice, and, flowing from the base of the glacier, hurry down the 

 slope into the plain below. Numerous observations have proved 



