142 Correspondence — Prof. A. H, Green. 



diffidence in approaching. With a large portion of Mr. Judd's 

 remarks I am confident that a very considerable majority, if not 

 all, even of the most enthusiastic supporters of the theory of Glacial 

 Erosion and of the doctrine of the sculpturing power of Subaerial 

 Denudation, will most cordially agree ; indeed, if a few paragraphs 

 had been omitted, I doubt if any one would have been found to raise 

 a word against the paper. But in his anxiety to make his arguments 

 as clenching as possible, Mr. Judd seems to me to have resorted to 

 that easy and safe way of securing a triumph, which consists in 

 setting up a dummy adversary in order to have the satisfaction of 

 knocking him down again. 



Two classes of geologists are alluded to who appear to me to be 

 pure phantoms of the imagination. The first are those who hold 

 that "all the existing rock-basins have been produced by ice erosion." 

 Where are these exquisite specimens of the man of one idea to be 

 found ? Who ever said that Lake Balaton, Lough Neagh, the Dead 

 Sea, or the Victoria Nyanza were excavated by glaciers ? 



What I must look upon as the second dummy is the geologist who 

 asserts that '' the production of the features of the earth's surface is 

 entirely due to the action of denuding agents, and that subterranean 

 forces have played no part whatever in the matter." Here again I 

 don't know where to lay my fingers on the man ; if he ventures to 

 show his face, he will assuredly receive as little mercy at the hands 

 of geologists in general as has been accorded him by Mr. Judd. 

 Such a doctrine is too palpably inconsistent for the veriest beginner 

 to accept it for a moment. Before denuding agents can carve out 

 hill and valley, they must have something to work upon ; the 

 material they have to fashion is either a derivative rock formed 

 under water, or a crystalline rock that once lay deep down in the 

 bowels of the earth. Without subterranean forces how are we to 

 get a rock of either class within the reach of denudation to begin 

 with ? Again, what is it that has caused the main lines of drainage 

 to run in many cases in the direction of the dip and directly athwart 

 the strike of the rocks ? Is it not one of the most fundamental 

 parts of the theory, which assigns the formation of the surface to 

 subaerial denudation, that it was the prevalent direction of the dip 

 of the underljdng rocks that determined the first slope of the surface 

 and gave the initial direction to the flow of meteoric water ? So far 

 from subterranean forces being ignored, subaerialists have all along 

 maintained that it was through them that the trend of the first 

 formed rivers was decided. Further, who has been bold enough to 

 assert that great mountain chains have been wholly cut out by denu- 

 dation ? Has it not been all along maintained, that while all the lesser 

 details of their contour are due to that cause, their superior elevation 

 is very largely owing to a concentration of the energy of subterranean 

 forces along certain zones of the earth's surface ? A theory well 

 borne out by the excessive contortion which is always found in lofty 

 ranges. I might add much more in support of my point, but I think 

 I have said enough to show that the geologists who are the objects 

 of such well-founded horror on Mr. Judd's part, are not to be found 

 either among the advocates of the possibility of rock-basins having 



