134 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. annexed table I recapitulate this relation of the fauna of the Coral- line Crag. Extinct. Living. Total. 1 4 5 23 126 149 2 2 ^ Grastropoda . . . 28 132 160 1 1 52 265 317 65 30 95 15 3 18 47 53 100 2 1 3 4 6 10 13 3 16 146 96 242 General Considerations. Between the period of the London Clay and that of the Coralline Crag the area now forming the Eastern Counties seems to have been dry land. Parts, however, of France and Belgium, together with parts of the south of England, had continued longer sub- merged, though successive elevations had brought much land to the surface during the later Eocene and early Miocene periods. The sea, however, still occupied the western area of Belgium and Hol- land. This sea gradually encroached in a westerly direction, and at the Pliocene period had spread over part of the eastern counties. As it spread in one direction the land rose in another ; and at the time of the formation of the Coralline Crag a portion of the Miocene and older Pliocene area of Belgium and the north- west of Erance (as, for example, the top of the chalk hills round the basin of Boulogne), and probably of Kent (Lenham and other parts of the North Chalk Downs), had been raised and exposed to the denuding action of the sea, in which the newer beds were in process of formation. As the sea extended northward, and the land rose to the south, the climate became colder, and we have evidence of ice-action even at the earliest period of the Coralline Crag ; for I do not see how other- wise than by transport by ice to account for the large block of por- phyry before mentioned in the basement-bed at Sutton. It is still a question whence this block may have been derived. I know of nothing analogous to it in the rock-specimens from the north of England and Scotland ; whether it came from Scandinavia or the Ardennes remains to be determined. The Oolitic remains were pro- bably derived from strata in Central England*. The abundance of London-clay fossils shows a great local denudation, and possibly also
- Mr. Boyd Dawkins refers the Pliosaurian vertebra to the Oxford or the
Kimmeridge Clay.
