AUSTEN TERTIARY DEPOSITS OF THE SUSSEX COAST. 71 



On the whole, I am disposed to consider that the fossiliferous de- 

 posits of Carentan more nearly correspond with those of Selsea than 

 they do with the Crag, and that the English Channel area was mostly 

 in the condition of dry land at the time that the area of the German 

 Ocean was occupied by the Crag-sea. 



The peculiar molluscan forms of the Selsea deposits point to a 

 limitation of a marine province in that direction, whilst their habits 

 indicate at the same time shallow water and marginal conditions ; 

 circumstances which concur in showing that for that period the 

 eastern extension of the channel may be represented by a line ex- 

 tending from the coast of Sussex to that of Lower Normandy *, and 

 that the remaining portion, or what is now the eastern end of the 

 English Channel, was in the condition of dry land. 



The connexion of our area with that of the Continent was de- 

 pendent on the continuity of those lines which connect our Wealden- 

 area with that of the Boulonnais. 



The temperature of the waters of the English Channel during the 

 period of the Elephas primigenius and its associates was such as 

 may now be met with twelve degrees further south. 



To this period there succeeded one of a much lower sea-tempera- 

 ture ; and this is indicated alike by a comparatively poor molluscous 

 fauna, and by the results of the formation of coast-ice ; but the con- 

 dition of the Channel-area, as to extent, must have been much the 

 same as during the former period, — provided the speculations as to 

 the source of the foreign materials found in the Sussex-levels be 

 correct (see p. 61). 



The old rock-masses which entered into the composition of that 

 former coast-line, and which are now traceable in 45 fathoms water, 

 imply that the depression producing the present central line of the 

 channel had at that time only extended thus far east. 



The first stage in this process of depression is that which is in- 

 dicated by the marine gravel-beds which overlie the accumulation 

 with the drifted boulders, and in which, as we have seen, we have 

 indications of only ordinary moving powers along the coast-line, and 

 a return of an assemblage of mollusca, without the peculiar forms of 

 the subjacent deposits, but very like such as we have now. 



This stage shows also that the sea then had a greater extension 

 than during the deposition of the boulder-group, as the gravels over- 

 lie and overlap it ; or, in other words, the eastern end of the channel 

 was depressed, so that its marginal line reached portions of the chalk- 

 ridge, as from near Brighton eastwards. 



The climatal conditions indicated by the brickearth-deposit are 

 excessive rain-fall and great moisture of the surface. The first 

 of these may be implied by the vast thickness to which these sub- 

 aerial beds sometimes attain, and the distances to which they have 

 been spread out ; the second is shown by the very general diffusion 

 of Succinea ohlonga. 



If the suppositions as to the equivalents of the brick- earth be 

 correct, then the depression of the remaining portion of the English 

 * See Map, PI. I. Quart. Journ. Geol. Soc. vol. xii. 



