﻿Vol. 66.~] THE WESTERN END OF THE WEALD. 647 



The comparative absence of this feature from the Lower Green- 

 sand escarpment must also be taken into account: while the 

 contrast between the straight parts of the Chalk just mentioned 

 and the extremely indented region between Alton and Petersfield 

 (which must, on any hypothesis, have been subjected to much the 

 same influences) still further strengthens my conviction that 

 straightness of the escarpment, in the region under review, cannot 

 be due to planatiou alone. 



(iv) Drifts. — Several different lines of argument may be deduced 

 from the drifts, and it will be well, as far as possible, to keep them 

 distinct. 



(a) F lints. — Great stress is laid by the older writers on the 

 distribution of flints over the Wealden surface. While almost 

 entirely absent from the Hastings Beds, they are very scarce on 

 the Weald Clay, but increase rapidly in quantity as we approach the 

 Chalk escarpment: and this was taken by Ramsay (21, 5th ed. 

 p. 344) and Topley (26, p. 290) to indicate that the Chalk had 

 been removed by marine planation to within a few miles of its 

 present position. 



Prestwich (19, p. 158) rejected this inference, and although his 

 reasons for doing so appear to me inadequate, and based in part 

 on a misapprehension, yet his conclusion, that no decisive evidence 

 of planation can be drawn from these facts, must, I think, be 

 accepted. If we suppose that the present physical features are 

 the result of prolonged subaerial denudation (with or without a 

 peneplain), then probably the Chalk would be first removed from 

 the central region, and any flint debris left there during the process 

 will have had a longer time in which to disappear. Although, 

 therefore, the distribution of flints presents some very interesting 

 features, which might repay further analysis, it cannot, if taken 

 alone, be held to prove planation. 



But, while this destroys the value of Ramsay's inference, we must 

 be careful not to attach too much importance to the converse 

 argument, and infer from the occasional presence of flints close to 

 the central axis (see 26, p. 200, and 4, pp. 637-38) that the sea has 

 not touched this region since the Chalk was removed. If a marine 

 plain ever existed, it must have left some deposits besides those of 

 the North Downs ; and although these are no longer recognizable, it 

 is quite possible that the fragments of flint found at Horsham, ' 

 Slinfold, etc. are remnants of such deposits gradually washed down 

 to a lower level, and broken by atmospheric influences into angular 

 fragments since their deposition. 



(b) Pliocene beds. — As early as 1857, Prestwich (17) boldly 

 assigned a Pliocene date to certain masses of sand and ironstone, 

 difficult to separate from the Drift, which occur at intervals 

 all along the Xorth Downs from Folkestone to Dorking. Ramsay 

 preferred to regard them as Eocene, but was prepared, if they 

 should prove to belong' to the Crag, to accept a Pliocene date for 

 his marine plain (21, 5th ed. p. 345). The Pliocene (Diestian) age 



