SECTION FROM LONDON TO BRIGHTON. 73 



Horley 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 each side the cutting. The general 

 dip of the strata hitherto passed is to the north- 

 east; but after crossing the deep wealden valley 

 beyond Balcombe, over a magnificent viaduct, the 

 line runs along alternating layers of sands and 

 clays, which dip to the south-west ; we have 

 therefore arrived on the southern side of the 

 grand anticlinal axis of the Forest ridge. The 

 Wealden strata continue with the same general 

 inclination by Hayward's Heath, which is traversed 

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

 they disappear beneath the lowermost greensand 

 beds of the chalk formation. The gait, firestone, 

 and marl succeed, and, lastly, the white chalk of 

 the South Downs, at Clayton Hill ; through the 

 base of which a long tunnel is carried, and emerges 

 on the Downs on the south. The remainder of 

 the line to the Brighton station, runs over, or 

 through, hills and valleys, of the white chalk. Thus 

 this railway passes through two ranges of chalk 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 



