1370.] WOOD — WEALD-YALLEr DENUDATION. 13 



gence and deaudatiou. The Glacial beds of East Anglia have un- 

 dergone a similar emergeuce and denudation ; and even those who 

 attribute the "Wealden denudation to atmospheric and fiuviatile 

 agencies admit that the Lower Tertiaries and Chalk over the south 

 of England underwent a previous denudation or planing oflf by marine 

 agency ; but where are the beds with marine fossils in East Anglia 

 or over the south of England representing such emergence and de- 

 nudation? These questions might be extended to the denudation 

 of the coal-measures and other old rocks ; but the phenomena pre- 

 sented by denuded area^ appear to me to show, uniformly, that a 

 denudation effected during upheaval* is wrarepresented by beds with 

 contemporaneous marine fossils deposited over the denuded area. 

 Upon any introduction afterwards of the sea, however, we get 

 these beds — as, for instance, the Kelsea gravel in Yorkshire, the fen- 

 gravels of East Anglia, and the brick-earth of the War in IN'orfolk : 

 but there has been no such reintroduction of the sea into the Weald 

 since its denudation, unless it be in the Lewes levels. The beds 

 with marine fossils contemporaneous with the Wealden denudation 

 are to be looked for without the "Weald, i. e. beyond the region of 

 upheaval and denudation ; and thus it is, as well as for the other 

 reasons assigned in the sequel, that I refer the fossiliferous mud-bed 

 of Selsea, lying in the depressed and wwdenuded fold between the 

 two areas of upheaval and denudation, the Isle of Wight and the 

 Weald, to the period of that upheaval and denudation. 



In the accompanying map, by means of shading in the escarpment 

 carefully reduced from the ordnance map, the very conspicuous 

 features of mouths opening towards the Weald, presented by the 

 gorges in the chalk escarpment between GuUdford and Dover, and 

 by that in the Lower-Greensand escarpment at Yalding, are made 

 apparent f. The gorges of the South Dowtis present no such feature. 



Now patches of gravel containing Tertiary pebbles occur near 

 one or other of these mouths : and it is clear that streams flowing 

 from the north through the Tertiary and Chalk area, and debouch- 

 ing through these mouths into a sea occupying the area within 

 these escarpments, would necessarily bring an abundance, both of 

 angular chalk-flint and of Lower-Tertiary pebbles into the Weald, 

 there to intermingle with fragments having their parentage within 

 the Weald itself. 



My proposition is that the violent disturbances from east to 

 west at some time subsequent to the older Tertiaries to which, it is 

 universally admitted, the Weald owes its present form % took place 



* It is the reverse with denudation during depression ; for there the advan- 

 cinc sea, as e. g. that of the Lower Tertiaries over the Chalk, planes off its floor 

 and then deposits its sediment with contemporaneous marine organisms — pre- 

 ceding this usually, however, with beds of rolled fragments. 



t To show better the physical features of the scarp, the strip of Atherfield 

 clay that forms the foot of the Lower-Greenaand escarpment has been shaded in 

 with the Weald clay, instead of, as is usual for geological grouping, with the 

 Lower Greensand. 



\ In order not to encumber the case discussed in the body of the paper, I have 



