On the Anticlinal Line of the London and Hampshire Basins. 127 



again bordered by anticlinal scarps of greensand^ at New Hall 

 on the south and Henfield on the north. The synclinal dispo- 

 sition is well -characterized north of Henfield. From Henfield, 

 or from the Adur, the line is carried on by a broad Weald-clay 

 valley as far as Homebush, where the escarpments of lower green- 

 sand again become confluent. A saddle of gait, another of malm 

 rock, and then the chalk of Poynings and Wolfstanbury succeed, 

 and appear to preclude all further progress to this upheaval. 

 Indeed I formerly thought that the line either terminated here, 

 or ran out through the chalk at Saddlescombe. But when 

 Mr. Lyell published his figure of the upheaved chalk at Souther- 

 ham near Lewes, with his speculations thereon*, I saw distinctly 

 that the longitudinal fissure of Greenhurst did enter the chalk, 

 and running out again eastward from Lewes, the probability 

 was that it would be found in its place, and be again instru- 

 mental in carrying back the chalk southward, as it had done west 

 of Wolfstanbury. 



These suspicions have since been verified by observation. The 

 line of elevation as it enters the chalk is the Valley of Piecomb, 

 Pangdean, and the north side of Stanmere Park. As it ap- 

 proaches the Ouse below Lewes, a deep denudation marks its 

 further progress, bounded by the strongly -marked chalk escarp- 

 ment south-west of Lewes, over Palmer, Kingstone and Iford. 

 Crossing the Ouse, the quarry in the northern escarpment of 

 this denudation, before spoken of, at Southerham cornerf^ pre- 

 sents a northerly dip of 30 or 40 degrees. The southern escarp- 

 ment becomes the line of the South Downs as they are carried on 

 towards East Bourne. Under Mount Caburn, and about a 

 quarter of a mile further east, the line is carried on in the lower 

 or gray chalk, which is there quarried. To this succeeds a saddle 

 of upper greensand stretching over from Glynde to Firle ; then 

 another of gait ; and then obscure indications of the outcrop of 

 the lower greensand. In this part of Sussex it is well known 

 that the sand in question thins out, or is in some way so lost to 

 view, that it might be passed over in a cursory survey of the 

 country, were it not known to be still certainly present J. Its 

 course appears to be this : it crops out in the usual order at 



* Principles of Geology. First edition. 



t So called at Lewes. 



X Mantell's Geology of Sussex and Geology of S.E. of England. 



I strongly suspect that the obscure outcrop of the greensands in this 

 part of our island, or rather their immersion, is mainly caused by the ope- 

 ration of this line of fissure. These beds form so prominent a feature in 

 all the country west of Lewes, and appear again in such force on the oppo- 

 site side of the Channel, in the Boulonnais, that it can hardly be supposed 

 that their obscurity in this intermediate space is the effect of a proper thin- 

 ning out. 



