364 



THE WONDERS OF GEOLOGY. 



Lect. IV. 



are succeeded by shales, limestones, sands, and sandstones, 

 to the Crawley station. 



Passing through a long tunnel in the 

 Wealden, we arrive at Balcombe, where 

 laminated sandstone and shale are seen on 

 8 - each side the cutting. The general dip of 

 | | the strata hitherto passed is to the north- 

 i E east ; but after crossing the deep wealden 

 £• S valley beyond Balcombe, over a magnifi- 

 ! cent viaduct, the line runs along alternat- 

 es ing layers of sands and clays, which dip to 

 H the south-west ; we have therefore arrived 



BE) ' 



° on the southern side of the grand anticlinal 



| (§|<-« g axis of the Forest ridge. The wealden strata 



^ continue, with the same general inclination, 



S by Hay ward's Heath, which is traversed by 



a tunnel, to beyond St. John's Common, 

 ^ „ where they disappear beneath the lower- 

 | h most greensand beds of the chalk forma- 

 ts ° tion. The gait, firestone, and marl succeed, 



g and, lastly, the white chalk of the South 



1 Downs, at Clayton Hill ; through the 

 | base of which a long tunnel passes, and 

 t emerges on the south of the Downs. 

 g The remainder of the line to the Brighton 

 g station, runs over, or through, hills and 

 I. valleys, of the white chalk. Thus this rail- 



| ^ way passes through two ranges of chalk 

 £ 2 hills, viz. the North and South Downs, 

 ^ by tunnels ; two of greensand, viz. near 

 Red Hill in Surrey, and Hurstperpoint 

 in Sussex; and two principal ridges of 

 wealden, riz. at Balcombe, and Hayward's 

 Heath. If we take a line bearing more 

 to the west ; as, for example, from London 



