200 THE RIVER VALLEYS OF 



on the chalk, forming a continuous escarpment of 

 that rock, but leaving behind it prominent masses 

 of greensand, to mark, but in places only, the site of 

 the ancient sea-cliff. From this it is apparent, that 

 although the escarpment is now being gradually 

 worked back by meteoric abrasion, yet it may have 

 been due originally to sea-work. The accompanying 

 sketch maps (figs. 25, 26, PL IV.) will explain how 

 this may happen. Fig. 25 represents a marine cliff in 

 one place cut entirely in chalk, and in another part 

 formed of chalk and greensand ; while fig. 26 repre- 

 sents the present chalk and greensand escarpments, 

 part of the latter being the base of the old sea-cliff, 

 while the sea-cliff that was entirely chalk has been 

 totally denuded away. If the Weald valley was solely 

 due to subserial denudation, there ought to be de- 

 posits of chalk flints over the whole area, and not 

 only on the newer beds. If, however, the sea formed 

 the original valley, it would have been capable of 

 carrying the flints out of it, and consequently flints 

 would only be found on the beds exposed by meteoric 

 abrasion, since the sea ceased to act. Furthermore, 

 when the sea retreated, the forest grew, and occupied 

 the "Weald clay and Hastings beds areas, protecting 

 them ; but meteoric abrasion was still working on the 

 chalk, denuding it backwards, and exposing the green- 

 sands and gault. 



It must be allowed that, at one time, there was 



