186 FRAGMENTS OF SCIENCE. 



in which I ascribed the paramount influence to glaciers. 

 The facts on which that opinion was founded are, I 

 think, unassailable; but whether the conclusion then an- 

 nounced fairly follows from the facts is, I confess, an open 

 question. 



The arguments which have been thus far urged against 

 tho 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 position 

 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 " bold- 

 ness" in that discussion beware lest they place themselves, 

 with reference 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 Oatarina to Bormio is thick 

 with it. The Rhine 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 culti- 

 vable laud are formed by the silt above the Lake of 

 Geneva. 



In the case of every glackc "we na?C two agents at work 

 the ice exerting a crushing force G i every point of its 

 bed which bears its weight, and eith >r rasping this point 

 into powder or tearing it bo lily froci the rock to which it 

 belongs; while the water which everywhere circulates upon 

 the bed of the glacier continually washes the detritus away 

 and leaves the rock clean for further abrasion Confining 

 the action of glaciers to the simple rubbing awaj' of the 

 rocks, and allowing them, sufficient time to act, it 'is not a 

 matter df opinion, but a physical certainty, that they will 



