EVIDENCE FROM GLACIAL PHENOMENA 31 



transporting power is greater, mile for mile, but in equal time the river 

 carries many times more material. Like the river, the glacier is not 

 burdened by the product of its own corrasion, but by the material which 

 other agents have given it. It is certainly true that rivers are the only 

 valley makers. We have no evidence that any glacier has ever carved 

 its own valley ; nor have we any proof that any glacier has greatly 

 deepened the valley it has occupied, notwithstanding the many asser- 

 tions, even in the text books. 



The above positive and rather dogmatic statement is confirmed by all 

 the observations on the phenomena of both living and extinct glaciers. 

 The Pleistocene glaciers have recently abandoned their channels and 

 have left us hundreds of examples of their work. Most living glaciers 

 are waning rapidly and exposing their recent work. In no case has 

 there been found any conclusive proof of valley making or. of basin 

 making in rock; but, on the other hand, there is a wealth of positive 

 and incontrovertible evidence that the ice has not seriously eroded its 

 bed. The quite unanimous testimony of geologists who are most 

 familiar with living glaciers is to the effect that they do almost no 

 erosional work, or scarcely more than sufficient to attest the fact of 

 their presence. Yet the glaciers of the Alps were at work during all the 

 life of the Pleistocene glaciers, which are assumed to have cut valleys 

 " thousands of feet " deep in granitic rocks, and the} 7, have continued to 

 work for some thousands of years longer and should show proportion- 

 ately better results. They show very little erosive effects. Plates 12-15 

 illustrate obstructions and irregularities in the beds of what have been 

 vigorous glaciers of the Alps, and similar examples can be indefinitely 

 multiplied, and doubtless from other fields. But wherein do the stronger 

 glaciers of the Alps differ in size or principle or function or effect from 

 those of the Sierras or Cascades or Alaska or Norway ? 



COX CRETE ILLUSTRATIONS 



Alps. — Apart from a group of eminent physiographers, the geologists 

 and alpinists who are familiar with the glacial phenomena of central 

 Europe are practically unanimous that glaciers are not effective agents 

 of erosion. The argument was traversed by Albrecht Heim in his 

 " Handbuch der Gletscherkunde." 



The continued retreat of the Alpine glaciers is now exposing sections 

 of their beds which have never been visible before and which are perti- 

 nent evidence in this discussion. If any valleys in Switzerland, Norway, 

 or elsewhere could have been greatly deepened by Pleistocene ice, it is 

 very strange that active glaciers, working thousands of years longer, 



