TIIK CKKTACEOUS SYSTKM 473 



With regard to their western range, in all prokibility the 

 Wealden and Vectian deposits did not extend much farther west 

 than tin- uin.-t westerly portions of them now existing. In Dorset 

 the Wealden i-xtnnls to Upway near Weymouth, being there 360 

 1'rrt thick^but is soon cut off by in tra- Cretaceous erosion; the 

 Vectian does not reach so far, but is cut off west of Mupe Bay ; 

 both, however, may originally have extended as far as Bridport. 

 In the Vale of Wardour near Dinton the two are less than 100 

 iVvt thick, and cannot have reached much farther west along that 

 line of latitude, for there the Vectian passes up into Gault. 



Coming now to the surface exposures of the older Cretaceous 

 Series, these are found in four separate districts (1) The Wealden 

 area, (2) The Isles of Wight and of Purbeck, (3) The Midland outcrop, 

 a long narrow one, (4) the north-east area in Norfolk, Lincoln, and 

 Yorkshire. The two southern areas may be described together as 

 they exhibit a similar succession of deposits, and are undoubtedly 

 connected beneath the Chalk of Hampshire. 



1. South of England 



The Weald is an oval-shaped area occupying portions of Kent, 

 Surrey, Hants, and Sussex (see map, Fig. 157) ; on the north-west 

 and south it is bounded by the escarpment of the Chalk, but 

 eastward it opens on to the English Channel between Eastbourne 

 and Folkestone. The district known as the Bas Boulonnais in 

 France is the eastern prolongation and termination of the Wealden 

 area, and the English and French districts are undoubtedly 

 continuous beneath the English Channel. The structure of this 

 area is generally described as that of an anticlinal ridge, but 

 in reality it more resembles that of an oval dome or inverted 

 boat. 



Fig. 158 is a diagrammatic section across the Weald from north 

 to south, showing its general structure and regarding only the 

 Cretaceous rocks ; Fig. 159 is a more complete and accurate section 

 taken along a line drawn from Beachy Head to Chatham. The 

 absence of the Lower Cretaceous below Chatham has been proved 

 by a boring there, which entered the Oxford Clay directly below the 

 Vectian sands, and this part of the section is reduced from that 

 drawn by Mr. W. Whitaker. 1 



In the Isle of Wight, and again in Sputh Dorset, from Swanage 

 to Ridgway near Weymouth, the Lower Cretaceous Series is 

 brought to the surface by a sharp anticlinal curvature. 



The following is a tabular view of the subdivisions which have 

 been made in the series as developed in these two districts : 



