Physical Geography. 231 



of a great continent, and that, during the formation of 

 the Lower Greensand, this land suffered partial sub- 

 mergence, but by no means to such an extent that the 

 Oolitic strata, which then extended far to the west, 

 round Wales, were entirely sunk beneath the sea in 

 which our Lower Greensand was deposited. 



As a whole, the Lower Grreensand, being a coarse 

 and sandy formation, was deposited in shallow water, 

 and great part of it was in the long run tranquilly 

 heaved out of the sea, to undergo terrestrial waste 

 and denudation before the deposition of the Gault 

 began. 



The deposition of the Grault in our area, first took 

 place on a surface of country that was being gradually 

 submerged, and part of the sediment was laid on the 

 Lower Greensand, and part on various members of the 

 Oolitic strata, from which the Lower Greensand had 

 been removed by denudation. This Gault Clay is, 

 however, so difficult to separate from the Upper Grreen- 

 sand in the eastern part of England, and the Upper 

 Greensand is so difficult to separate by any clear line from 

 the Chalk, that it now becomes necessary to consider 

 the question of the mode of deposition of all three, if, 

 indeed, except as local developments of different sedi- 

 mentary character, they ought not to be considered, on 

 a broad scale, as only one formation. Right or wrong, 

 the origin of this idea was first declared by Mr. Godwin- 

 Austen, whose large giasp of questions in physical 

 geology, (to be found only in scattered memoirs, and un- 

 fortunately often only spoken in accidental remarks,) is 

 by no means so well known as it would have been, had 

 he printed all his stores of geological knowledge in 

 consecutive form. All that I know of this subject with 

 respect to these Cretaceous formations, is in the first 



