﻿276 Rev. T. G. Bonney — Formation of Cirques. 



depth, how are the excavated materials removed ? When there is 

 much pressure from the ice behind, that in front may be forced uphill 

 for a short distance, and a sort of scooping action maintained ; but 

 I fail to see how this could happen with Mr. Helland's theory. 



3. The size of some of the cirques appears to me also a fatal 

 objection. The walls of the cirques in the Alps and Pyrenees, like 

 those described by him, are often 2000' or 3000' higk Indeed one 

 might almost call those of the Creux de Champs double that; for 

 the precipices (as I well know) rise with inaccessible steepness, 

 interrupted by mere ledges, from tbe floor of the cirque to the very 

 crest of the Diablerets. Does Mr. Helland seriously mean to say 

 that " a small isolated glacier " has settled almost vertically down- 

 wards on the site of this cirque, deepening its bed by a thousand 

 yards, — and that too beneath its neve, where the erosive power is 

 weakest ? 



I am content to ask any one to replace the material removed from 

 one of these great cirques, to clap a glacier on some accidental hollow 

 on the mountain, and then to consider if the problem proposed is 

 mechanically possible. We should want the "rotatory glaciers — 

 whirlpools of ecstatic ice — like whirling dervishes," which Mr. Euskim 

 long ago suggested, to perfonn work like this. 



4. But suppose for one moment we are not staggered by this 

 feat of excavation. Suppose we imagine a thousand yards of rock 

 dug almost vertically out of the mountain- side. Are we not then 

 forced to admit one of the following alternatives ? If this energetic 

 glacier was limited to tlie immediate vicinity of the cirque, then 

 the floor of this part of the valley ought to be lower than that 

 further down ; in other words, there should always be a deep lake 

 beneath the walls of the cirque (which there is not) : or else the 

 valley must have been immensely deepened and modified, almost 

 excavated, by the glacier. It is this latter alternative which I 

 understand Mr. Helland to accept; it is this which in my first 

 paper I endeavoured to show was inevitable.; and it is exactly this 

 which is not only unsupported but even opposed by the evidence 

 of the Alps and of every mountain region which I have seen. 

 As I have endeavoured again and again to show in arguing against 

 the ai^plication of the theory of glacial excavation to the greater 

 Alpine lakes, we have in the valleys little or no indication of any 

 but the most superficial effects of glacial erosion. These valleys 

 commonly have the characteristic forms of river action. In the 

 Val Sesia, Val Bregaglia, in the valle}'- of the Dranse and many 

 more, I have traced glacial marks almost down to the present 

 torrent bed, where the valley itself exhibits the most characteristic 

 foi-ms of fluviatile erosion. The contours also of the valley below 

 Gavarnie are those of river, not of glacial erosion. If then the 

 erosive effect of glaciers is so slight that it is difficult to credit them 

 with the greater Alpine lakes, how can we attribute to them cirques, 

 which occur just at the point where they are feeblest, where the con- 

 nexion with the formation of the whole valley is most inseparable? 



Lastly, Mr. Helland objects to my theory " that the part of the 



