274 



CHALK ESCARPMENTS. 



[Ch. XIX. 



Mr. Martin has suggested that the great cross fractures of the chalk, 

 which have become river channels, have a remarkable correspondence 

 on each side of the valley of the Weald ; in several instances the gorges 

 in the North and South Downs appearing to be directly opposed to each 

 other. Thus, for example, the defiles of the Wey in the North Downs, 

 and of the Aran in the South, seemed to coincide in direction ; and in 



like manner, the Ouse corre- 

 sponds to the Darent, and the 

 Cuckmere to the Medway.* 



Although these coincidences 

 may, perhaps, be accidental, it 

 is by no means improbable, as 

 hinted by the author above 

 mentioned, that great amount 

 of elevation towards the centre 

 of the Weald district gave rise 

 to transverse fissures. And as 

 the longitudinal valleys were 

 connected with that linear move- 

 ment which caused the anti- 

 clinal lines running east and 

 west, so the cross fissures migh 

 have been occasioned by the 

 intensity of the upheaving force 

 towards the centre of the line. 



But before treating of the 

 manner in which the upheaving 

 movement may have acted, T 

 shall endeavor to make the 

 reader more intimately acquaint- 

 ed with the leading geographi- 

 cal features of the district, so 

 far as they are of geological in- 

 terest. 



In whatever direction we travel 

 from the tertiary strata of the 

 basins of London and Hamp- 

 shire towards the valley of the 

 Weald, we first ascend a slope 

 of white chalk, with flints, and 

 then find ourselves on the sum- 

 mit of a declivity consisting, for 

 the most part, of different mem- 

 bers of the chalk formation ; 

 below which the upper green- 



Geol. of Western Sussex, p. 61. 



