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 
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 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 Catarina 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 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 away 
and leaves the rock clean for further abrasion Confining 
the action of glaciers to the simple rubbing away of the 
rocks, and allowing them sufficient time to act, it is not a 
matter of opinion, but a physical certainty, that they will 
