Remarks on Glaciers. 383 



two lines if attaining as much. They were always of a fine uni- 

 form yellow colour, the body very flexible and of variable 

 shape ; and they invested themselves with such muddy par- 

 ticles as came in contact with them. 



Remarks on Glaciers. By M. Agassiz.* 



In laying before you, gentlemen, a few details regarding 

 glaciers, and the phenomena attending them, I design to con- 

 fine myself exclusively to matter of fact. I shall submit to you 

 the principal observations which have been made on this"in- 

 teresting subject ; to these I shall add a few others which I 

 believe to be new ; and finally, bring to yoiu- recollection some 

 which have been known from the time of Saussure, but pro- 

 bably forgotten, because he did not connect them with the 

 phenomena of glaciers, on which they really depend. 



A glacier is a mass of ice hanging on the sides of an Alpine 

 ridge, or enclosed in one of its valleys, and which is moving 

 continually dow the declivity. I say continually, for the gla- 

 cier is always descending ; if the extremity should at any time 

 seem to retire, this implies nothing more than that the portion 

 of the ice, melted by the heat of summer, is more considerable 

 than that which the glacier brings along with it in its progress. 

 This movement of the ice, which many refused for a long 

 while to admit, is now known and acknowledged by every 

 observer ; but there is a great contrariety of opinion respecting 

 the cause which produces it. The opinion generaUy received 

 from the time of Saussure, is, that the descent of a glacier is 

 nothing more than a slipping upon itself, occasioned by its own 

 weight. But there are many reasons for doubting the accu- 

 racy of this explanation. The motion appears to be much 

 more properly ascribed to the expansion of the ice residting 

 from the congelation of the water which has filtered into it 

 and penetrated its cavities. The ice of glaciers, it must be ob- 

 served, has not the continuous texture of ordinary ice; it is com- 

 posed of a multitude of fragments, which have been improperly 



* Kead to a meeting of the Geological Society of France. 



