THE GREAT ICE AGE 359 



the stones on the surface of the glacier are ever falling into 

 crevasses, and thus reach the bottom of the ice, where they are 

 further ground one against another and the floor of rock. In 

 the movement of the glacier these stones seem in some cases 

 to come again to the surface, and their remains are finally dis- 

 charged in the terminal moraine, which is the waste heap of 

 this great mill. The fine material which has been produced, 

 the flour of the mill, so to speak, becomes diffused in the water 

 which is constantly flowing from beneath the glacier, and for 

 this reason all the streams flowing from glaciers are turbid with 

 whitish sand and mud. 



' The Arve, which drains the glaciers of the north side of 

 Mont Blanc, carries its burden of mud into the Rhone, which 

 sweeps it, with the similar material of many other Alpine 

 streams, into the Mediterranean, to aid in filling up the bottom 

 of that sea, whose blue waters it discolours for miles from the 

 shore, and to increase its own ever-enlarging delta, which 

 encroaches on the sea at the rate of about half a mile per 

 century. The upper waters of the Rhone, laden with similar 

 material, are filling up the Lake of Geneva; and the great 

 deposit of " loess " in the alluvial plain of the Rhine, about 

 which Gaul and German have contended since the dawn of 

 European history, is of similar origin. The mass of material 

 which has thus been carried off from the Alps, would suffice to 

 build up a great mountain chain. Thus, by the action of ice 

 and water 



"The mountain falling comelh to naught, 

 And the rock is removed out of its place." 



Many observers who have commented on these facts have 

 taken it for granted that the mud thus sent off from glaciers, 

 and which is so much greater in amount than the matter 

 remaining in their moraines, must be ground from the bottom 

 of the glacier valleys, and hence have attributed to these 



