Correspondence — Professor E. Hull. 479 



arguments I there brought forward may possibly modify his views 

 on the question of the submerged physical features of the North 

 Atlantic. 



Mr. Jukes-Browne objects to the term 'escarpment' as applied 

 to the great declivity along which the Anglo-Continental platform 

 terminates, both on the ground of its great lateral extension and 

 because of its elevation. These are only matters of degree. The 

 question is really one of form, and to my mind on the ground of 

 form the term is correct ; the declivity has a terraced upper surface, 

 has a descent, sometimes almost precipitous, and falls off in a slope, 

 sometimes gentle, at its base into the abyssal plain. Putting 

 geological structure aside, which in this case is inadmissible, this 

 is the form of the escarpments of the Oolite, New Red Sandstone, 

 Millstone Grit, and older rocks in this country and of parts of 

 Europe. I do not know on what ground the writer objects to the 

 range of the Nummulite Limestone along the south of the Nile Delta 

 being called ' technically ' an escarpment. Perhaps he has not 

 himself seen its eastern extremity of Jebel Attaka, where it over- 

 looks the Red Sea, and is one of the grandest escarpments I have 

 ever seen as viewed from Suez. 



The writer objects to the statement that I have expressed re- 

 garding these submerged physical features having been formed 

 under terrestrial conditions ; but he omits to mention the one crucial 

 test of their terrestrial formation, namely, the river channels some- 

 times traceable up to or in proximity to the existing rivers draining 

 the adjoining lands. He was probably not aware when he wrote 

 his letter to what extent I have been able to determine these 

 channels or caiions along the whole coastline from the English 

 Channel to the Tagus. Such channels, with well-defined walls 

 and ever deepening floors as we proceed outwards, cross the con- 

 tinental platform and the great escarpment opening out on the floor 

 of the ocean at depths of 1,000 to 1,500 fathoms. One of these, 

 commencing at the embouchure of the Adour, is so continuous and 

 remarkable that Elisee Eeclus, not recognizing its true nature, 

 contents himself with exclaiming " What shall we say of that deep 

 gulf?" etc., and leaves the question for answer to the future! 

 I quite admit that in the absence of this succession of great channels, 

 each one of which becomes accumulating evidence of its true nature, 

 the question of the origin of the escarpment might have remained 

 problematical, and it might have been supposed, for instance, that it 

 represented the edge of a great depression of the ocean bed. But the 

 river channels, which we cannot conceive could have been formed 

 beneath the ocean itself, are, as it seems to me, the unquestionable 

 proof of subaerial origin, both of themselves and of the physical 

 features with which they are connected. Let Mr. Jukes-Browne 

 procure the Admiralty Charts for himself and trace out the isobathio 

 contours by means of the soundings, and then state his conclusions 

 regarding the views which have been impressed on my own mind. 



As regards the geological periods during which the features were 

 elaborated, I cannot here discuss the question. I admit that I have 



