546 



EFFECTS OF ELEVATION UPON THE BED OF THE SEA. 



and down to widely different levels. Is it not, therefore, a fair inference, that during 

 the recent elevation of the continents and islands over which these bowlders are distri- 

 buted, there must have been movements of very different degrees of intensity, at com- 

 paratively recent dates, affecting the different portions of the tracts in question ? If 

 partial elevations at some points and depressions at others, occurred during the desicca- 

 tion of the bottom of the sea (and it is obvious such changes must have happened), 

 many of the submarine valleys and hills must have thereby been much modified. 



Adhering, therefore, to the prevalent belief of modern geologists, founded on a multi- 

 tude of well-recorded facts, that the land has been repeatedly elevated and depressed in 

 relation to the sea level, I confess my inability to imagine how such mutations can 

 have been accomplished without involving, as a necessary result, the repeated fracturing 

 of all the subjacent strata. In viewing the present surface, we are not to expect that 

 the loose materials of the bed of the sea should, when elevated, exhibit lines of fault, as 

 clearly and neatly defined as those impressed upon the solid strata which support them • 

 the only memorials we could expect to find of the dismemberment of the loose aggregate, 

 being what we now witness ; — the separation and removal to various heights of gravel 

 beds which were once continuous. For we must recollect, that under the view here 

 adopted, the space between the elevated and stationary parts, or between those elevated 

 and depressed, would always be exposed to the same action as a sea beach, and there- 

 fore such portions would be rounded off, and the final result would be the appearance 

 of a covering spread more or less equably over the whole tract. Such elevations in 

 throwing off large bodies of water must, it has been shown, have materially aided in the 

 partial transport of many of the fragments. 



Lastly, elevations to the extent we have now supposed, can hardly have affected so 

 large a portion of our western shores, without producing a great effect on the relations 

 of land and sea on the other coasts of the island ; and as from collateral evidences we 

 already know, that great part of our eastern shores was submerged at an equally modern 

 period, because the same species of sea-shells are there also found in gravel, we may 

 infer that, by whatever means accomplished, the estuaries of the Humber and the 

 Thames, and the coasts of Devonshire and Cornwall, were desiccated during the same 

 period as the plains of Shropshire and the estuaries of the Mersey and the Severn 1 , 



1 See a memoir by Professor Sedgwick and myself on the raised beaches of Devon and Cornwall, Geological 

 Proceedings, vol. ii. p. 441. Similar raised beaches, inclosing sea-shells of existing species, have been observed 

 at various points along the eastern shores. See memoirs by Mr. W. Hamilton on the shores of Fife, Geological 

 Proceedings, vol. ii. p. 180. ; by Mr. Prestwich on the shores of Banffshire, Geological Transactions, vol. v, 

 p. 139.; by Professor Phillips on the coast of Yorkshire; and by Mr. Smith, of Jordan Hill, Geol. Pro- 

 ceedings, vol. ii. p. 427., on the western shores of Scotland. The last-mentioned gentleman has very much 

 enlarged our knowledge of this subject by very extensive collections and accurate determination of the 

 speeies of shells. I may also mention a raised beach at Cranfield Point near Carlingford, Ireland, observed 

 by Professor Sedgwick and myself, in company with Mr. Hamilton and Mr. W. D. Hull, in the summer of 

 1835, as its component parts and general aspect much too closely resemble the coarse and fine accumulations 



