37 



PROCEEDINGS 



OF 



THE GEOLOGICAL SOCIETY. 



POSTPONED PAPER. 



On the Lines of Deepest Water around the British Isles. 

 By the Rev. R. Eterest, F.G.S. 



(Eead June 19, 1861*.) ,^ 



[Abridged.] 



FfiOii two papers by Mr. Godwin- Austen t we learn that the English 

 Channel was, in all probability, a valley of depression. If, by the 

 light thus afforded us, we examine the locality as laid down in a 

 good chart, we shall see that as there is a valley of depression, so is 

 there also an axis of depression, if the term may be used. We have 

 in common use the term '' axis of elevation " to signify the line of 

 greatest elevation in a mountain-range ; and in a similar way we 

 would employ the phrase '* axis of depression " to mean the line of 

 deepest water in a naiTow sea. 



If we take a point (see Map) nearly south of Dungeness in Kent, 

 or in north lat. about 50° 30', and east long, rather less than 1°, and 

 from this draw a straight line a little to the south of west, passing 

 through the middle of the deep water, and meeting about north lat. 

 4S° 20', and west long. 8° 20', and another line of a similar kind pass- 

 ing through the deepest water of the St. George's Channel between 

 Ireland and England, we find, tracing the course of our line, that it 

 first passes between the two pits, called " I^orth Deep " and " South 

 Deep," in the same longitudinal or axial direction as both of them ; 

 it cuts the " West Deep" in its deepest part, and nearly in the same 

 longitudinal direction ; it passes through the *' Hurds Dyke " from 

 end to end, and meets successively the projecting easternmost points 

 of the Hues of 40 to 50, 50 to 60, and 60 to 70 fathoms. Beyond 

 this last, the lines of equal depth are but triflingly affected by the 

 entrance to the Channel. See the Admiralty Charts. 



We would now wish to draw attention to the above-mentioned 

 longitudinal pits, remarkable as they are for their great length, and 

 for hnng, all of them, nearly in the same direction. 



It has, I think, been suggested that a large river once passed 



* For the other papers read at the Evening-meefing, see Qiiai't, Jouni. Geql. 

 Soc. vol. xvii. p. 53i3, &o. 

 t Quart. Joum. Geol. Soc. 1850-51 ; vol. vi. p. 60 ; vol. viii. p. 1 18. 



