Correspondence — Mr. A. J. Jukes-Browne. 95: 



elevation. By referring to my letters published in September and 

 November last your readers can see for themselves whether these 

 statements are true or false. Dr. Spencer must have read my 

 remarks so hastily that he failed to understand the drift of my 

 argument, and perhaps when he succeeds in realizing that I did 

 not anywhere deny either the subsidence or elevation of the con- 

 tinental margins he will have the courtesy to acknowledge that he 

 has done me an injustice. 



He accuses me of " turning the correspondence into an academic 

 disputation of the meaning of the word 'escarpment,'" and into 

 a " flat denial of the evidence submitted by Professor Hull." I hope 

 to show that I did neither of these things. 



Ever since Mr. Whitaker carefully distinguished between the 

 features presented by a steep slope fashioned entirely by subaerial 

 agencies and those of a raised sea-margin or cliff,^ English geologists 

 have restricted the terra escarpment to the former, and have thought 

 that the primary origin of the slope was a point of some importance. 

 Dr. Spencer tells us that by American geologists the descent from 

 a tableland or plateau is termed an escarpment, and he implies that 

 they do not trouble themselves to ask whether the course of the 

 feature was determined by the sea or by subaerial agencies. Of 

 course Dr. Spencer ought to know, and I can only express surprise 

 at what he says is American usage. 



Again, Dr. Spencer asserts that I flatly denied Professor Hull's 

 evidence. Now most people reading such a statement would suppose 

 that I had flatly contradicted Professor Hull on statements of fact, 

 which is very far from being the truth. Hence I am led to ask 

 whether Dr. Spencer has any clear conception of the difference 

 between evidence and inference. 



I could wish that Professor Hull had displayed his facts more 

 fully by I'eproducing some of the actual charted records, but I did 

 not question the accuracy of his observations, nor his inference 

 that the submerged plateau was once a land-surface and that traces 

 of river-valleys may be found upon it. It was not his evidence but 

 his further and more theoretical inferences that I questioned. 



What I denied, and still deny, is that Professor Hull adduced any 

 evidence to prove that the steep declivity which forms the border 

 of the plateau was an escarpment in the English sense of the term, 

 in other words that it has been formed and fashioned entirely by 

 subaerial agencies. Not only did Professor Hull assume that it was 

 so formed, but he further assumed, without proof and without 

 consideration of other possibilities, that the platform was formed 

 first and the declivity afterwards. Further, he referred these events 

 to definite periods of geological time. I asked him to give his 

 reasons for these conclusions, but in his reply (October) he did not 

 answer the two latter questions (promising, however, to discuss one 

 of them later on), and confined himself to defending his use of the 

 term escarpment. Is it surprising that my rejoinder was similarly 



1 Geological Magazine, Vol. IV, pp. 447 and 483 (1867). 



