370 PERIODS OF WEALD DENUDATION. [Oh. XIX. 



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

 spoken of (fig. 365, p. 368) 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 

 Chap. XVI.) are found in any part of the London area. 



Fifthly. The fossils of the alternating marine, brackish, and fresh- 

 water beds of Hampshire, of Middle and Upper Eocene date, bear 

 testimony to rivers draining adjacent lands, and to *the existence of 

 numerous quadrupeds in those lands. 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 before 

 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 

 frequently, and, oftener than any adjoining area, been turned from 

 sea into land and land into sea ; for the submergence and emergence 

 of land augment, beyond any other cause, the wasting and removing 

 power of water, whether of the waves and tides or of rivers and 

 land-floods. 



Sixthly. The Lower Miocene strata of the Isle of Wight (or the 

 Hempstead beds before described) have been upraised several hundred 

 feet above the level of the sea in which -they were originally formed. 

 This upward movement 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 suggested (p. 242). Hence we are 

 entitled to speculate on the probability of revolutions in the physical 

 geography of the adjoining Weald in times intermediate between 

 the deposition of the Hempstead beds and the origin of the Suffolk 

 crag. 



Seventhly. We have already seen (p. 235) that certain ferruginous 

 sands lie in patches on the North Downs, some of them from 20 to 40 

 feet in thickness, and referable by their fossils to the same age as the 

 Diest sands of Belgium. They are probably somewhat older than the 

 coralline crag of Suffolk, and, as before explained, may constitute the 

 only representative in the British Isles of the Upper Miocene or 

 Falunian epoch. It is clear, from the relative position of the sands in 

 question on the North Downs to the Lower Eocene deposits of the 



