284: AT WHAT PERIODS [Cn. XIX. 



share in the movement, and some parts at least of the island before 

 spoken of (fig. 330, p. 282) would become submerged. 



Fourthly. After the London clay and the overlying Bagshot sands had 

 been deposited, they appear to have been upraised in the London basin, 

 during the Eocene period, and their conversion into land in the north 

 seems to have preceded the upheaval of beds of corresponding age in the 

 south, or in the Hampshire basin ; because none of the fluvio-marine 

 Eocene strata of Hordwell and the Isle of Wight (described in Ch. XVL) 

 are found in any part of the London area. 



Fifthly. The fossils of the alternating marine, brackish, and freshwater 

 beds of Hampshire, of Middle and Upper Eocene date, bear testimony to 

 rivers draining adjacent lands, and to the existence of numerous quadru- 

 peds in those lauds. Instead of these phenomena, the signs of an open 

 sea might naturally have been expected, as ■ a consequence of the vast 

 subsidence of the Middle Eocene beds befoi'e mentioned, had not some 

 local upheaval taken place at the same time in the Isle of Wight or in 

 regions immediately adjacent. Whatever hypothesis be adopted, we are 

 entitled to assume that during the Middle and Upper Eocene periods 

 there were risings and sinkings of land, and changes of level in the bed of 

 the sea in the southeast of England, and that the movements were by no 

 means uniform over the whole area during these periods. The extent and 

 thickness of the missing beds in the Weald should of itself lead us to look 

 for proofs of that area having by repeated oscillations changed its level 

 frequentl}^, and, oftener than any adjoining area, been turned from sea into 

 land ; for the submergence and emei'gence of land augment, beyond any 

 other cause, the wasting and removing power of water, whether of the 

 waves or of rivers and land-floods. 



Sixthly. As yet we have discovered no Marine Miocene (or faluniaii) 

 formations in any part of the British Isles, nor any of older Pliocene 

 date south of the Thames ; but the Upper Eocene strata of the Isle 

 of Wight (the Hempstead beds before described) have been upraised 

 above the level of the sea in which they were originally formed, and 

 some of them have been thrown into a vertical position, as seen in 

 Alum and WhiteclifF Bays, attesting great movements since the origin 

 of the newest tertiaries of that district. Such movements may have 

 occurred, in great part at least, during the Miocene period, when a 

 large part of Europe is supposed to have become land as before sug- 

 gested (p. 180). Hence we are entitled to speculate on the probability 

 of revolutions in the physical geography of the Weald in times inter- 

 mediate between the deposition of the Hempstead beds and the origin of 

 the Suffolk crag. 



Seventhly. But we have still to consider another vast interval of time 

 — that which separated the beginning of the older Pliocene from the be- 

 ginning of the Pleistocene era, — a lapse of ages which, if measured by the 

 fluctuations experienced in the marine fauna, may have sufficed to uplift 

 yc sink whole continents by a process as slow as that which is now opera 

 tinof in Sweden and in Greenland. 



