Correspo7idence — Mr. T. V. Holmes. 189 



most generally accepted theories in geology," is it possible to avoid 

 a smile at the very sanguine temperaments with which the promoters 

 of this theory would appear to be so happily endowed ? 



I have, however, to thank Prof. Green for so fairly raising what 

 is the real point at issue in this controversy — that of the relation 

 between the effects of subterranean and subaerial forces. He tells 

 us that he and his friends are prepared to admit that before denuding 

 agents can carve out hill and valley, the subterranean forces must 

 have brought the rock-masses within their reach ; he is moreover 

 convinced that the original lines of drainage must have been deter- 

 mined by the action of the same forces ; and, still further, that, 

 though the details of the contours of mountains are due to meteoric 

 agencies, their superior elevation is the result of the concentration 

 of subterranean energy beneath them. 



So far well ! But will my friend permit me to invite him to 

 accompany me just one step farther in the same direction. Is 

 it not certain that not only before the commencement of the slow 

 process of sculpturing by meteoric agencies (in which we are both 

 such firm believers), but actually while those forces are in operation, 

 subterranean actions, attended by more or less local surface move- 

 ments, were going on side by side with, and modifying the effects of. 

 the subaerial forces ? Does he shrink from this admission ? If 

 so, why ? Has he any grounds for the belief that all the sub- 

 terranean action took place at one period, and all the subaerial at 

 another? Such an admission as I ask him to make would never 

 have alarmed either Lyell or Scrope, who fought a good fight for the 

 Huttonian doctrines before almost any of us the younger champions 

 of the theory were born! Is there anything in it inconsistent with 

 the teachings of Hutton and Play fair themselves ? 



Have not our perceptions become just a little numbed through our 

 dwelling too long in the region of glaciers ? Geology has had its day 

 of universal deluges ; it is now passing through its " great ice age." 

 We are persuaded, however, that as it has survived the former, it 

 will emerge safely from the latter ; and even now we begin to see 

 the signs of the setting in of more temperate mental conditions. I 

 cannot help venturing to hope (for may not I too be sanguine, for 

 once ?) that at no very distant date I may have the pleasure of 

 wandering with my four opponents of to-day among Alpine or 

 Scottish lakes, all joining in a hearty laugh at the strange theory 

 that was once maintained concerning their origin. 



John W. Judd. 



GLACIAL EROSION. 



SiR: — In Mr. Judd's very interesting paper on Lake Balaton, 

 there is, besides a vindication of the claims of subterranean forces to 

 be the true originators of lakes lying in rock-basins, an attempt to 

 show that glacial erosion can never be regarded as a vera causa in 

 any case in the formation of lakes. 



I am afraid that the eminent geologists who write on behalf of 

 glacial erosion, as one of the causes producing lakes, in the current 



