﻿640 ME. H. BUEY ON THE DENUDATION OF [Nov. 1 9 10, 



26. The Denudation of the Western End of the Weald. By 

 Henry Buey, M.A., F.L.S., F.G.S., formerly Fellow of Trinity 

 College, Cambridge. (Read June 15th, 1910.) 



Contents. 



Page 

 I. Introduction 640 



II. Be-new of Existing Hypotheses 643 



(A) General Evidence in favour of a former Plain (Marine or 



S u bae rial ) 643 



(i) Coincidence of the Highest Levels throughout the Area, 

 (ii) Even Bevelling of the Crest of the Escarpment. 



(iii) Straightness of the Escarpments. 



(iv) Drifts. ' 



(B) Hypothesis of a Subaerial Peneplain 649 



(C) Prestwich's Hypothesis 650 



(D) Warpings of the Plain 652 



III. Evidence of Rivers 658 



(A) Their Relation to the Rock-Folds 658 



(B) River Blackwater 661 



(C) River Wey 672 



(D) River Mole 676 



(E) River Arun 680 



(F) River Adur 686 



(G) General Remarks 688 



IY. Bibliography 691 



I. Inteoduction. 



The old ' sea-cliff' theory of Wealden denudation, which regarded 

 the escarpments as the direct result of marine action, has long 

 disappeared, and no one now doubts that the main physical features 

 of this district have been produced by subaerial agencies. Beyond 

 this, however, there is but little unanimity. Whether the subaerial 

 process has been continuous since early Oligocene times ; whether 

 it can be divided into two cycles, with a peneplain between; or 

 whether the removal of the top of the dome has been assisted by 

 marine planation, are questions so undecided that, except on the one 

 point already mentioned, geologists are perhaps in no closer agree- 

 ment as to the physical history of the Wealden area than they were 

 thirty years ago. 



In the second section of this paper the older lines of evidence are 

 reviewed, and in places supplemented by new arguments, tending 

 to show that the theory of marine planation is the one which, on 

 the whole best, embodies the observed facts. In the third section 

 the history of the four western rivers (Wey, Mole, Arun, and Adur) 

 is examined, and the same inference drawn. Whether this explana- 

 tion holds good for other parts of the Wealden area must be left to 

 future investigation. 



The expression ' plane of marine denudation ' is said by Foster & 



