258 FRAGMENTS OF SCIENCE 



the conclusion are not convincing. Indeed, the idea of 

 glacier erosion appears so daring to some minds that its 

 boldness alone is deemed its sufficient refutation. It is,^ 

 however, to be remembered that a precisely similar posi- 

 tion was taken up by many excellent workers when the 

 question of ancient glacier extension was first mooted. The 

 idea was considered too hardy to be entertained; and the 

 evidences of glacial action were sought to be explained by 

 reference to almost any process rather than the true one. 

 Let those who so wisely took the side of "boldness" in 

 that discussion beware lest they place themselves, with ref- 

 erence to the question of glacier erosion, in the position 

 formerly occupied by their opponents. 



Looking at the little glaciers of the present day — mere 

 pygmies as compared to the giants of the glacial epoch — 

 we find that from every one of them issues a river more 

 or less voluminous, charged with the matter which the ice 

 has rubbed from the rocks. Where the rocks are soft, the 

 amount of this finely pulverized matter suspended in the 

 water is very great. The water, for example, of the river 

 which flows from Santa Catarina to Bormio is thick with 

 it. The Khine is charged with this matter, and by it has 

 so silted up the Lake of Constance as to abolish it for a 

 large fraction of its length. The Rhone is charged with 

 it, and tens of thousands of acres of cultivable land are 

 formed by the silt above the Lake of Geneva. 



In the case of every glacier we have two agents at work 

 — the ice exerting a crushing force on every point of its 

 bed which bears its weight, and either rasping this point 

 into powder or tearing it bodily from the rock to which 

 it belongs; while the water which everywhere circulates 

 upon the bed of the glacier continually washes the detritus 



