178 STcetch of the Geology of the Neighbourhood of Shaftesbury . 



buried beneath the oolitesj the central part of England was a plain, 

 bounded by the hills of the north. How far to the west the land 

 extended we cannot say, to the east it stretched right away to the 

 continent. 



This period is known as the Wealden from the Weald of Kent 

 and Sussex, where these estuarine deposits are exposed by the removal 

 by denudation of the cretaceous strata, which were subsequently 

 deposited on them. The wealden system consists of: — 

 Weald clay. 



Hastings sands and clay. 

 Purbeck limestone. 

 Slow submergence now set in, and the sea gradually occupied the 

 wealden area, the fresh water weald clay almost imperceptibly 

 passing into the marine Atherfield clay of the Isle of Wight, which 

 also encircles the Weald of Kent and Sussex. 



Next the lower greensand was deposited, in seas still shallow. 

 After its deposition it was elevated, denuded, and then again sank 

 beneath the sea ; and as the land sank the gault — a stiff bluish 

 micaceous clay — was deposited uncomformably on the edges of the 

 older and slightly-tilted strata. This gault underlies the hill on 

 which our town is built, and its exposed edge is marked on the map 

 by the dark blue band which runs round this hill and skirts b(>th 

 sides of the Vale of War dour. The sinking still continued near the 

 western shore of the sea ; the coarse-grained greensand was de- 

 posited, while, at a greater distance from the shore, towards the 

 east, finer particles were laid down, forming fine-grained calcareous 

 rock, akin to chalk, for it is always noticed that the heavier particles 

 borne down by streams to the sea settle near the shore, while the 

 finer ones are often carried by the force of the current far out to sea. 

 As the sinking still continued the greensand deposits followed the 

 shore, retreating westward, and outlying patches of this formation 

 in Devon show how far to the west the sea flowed in these ages ; in 

 the east, where the water was much deeper, calcareous ooze, composed 

 of the remains of tiny organisms which sank to the bottom of the 

 deep sea, somewhat resembling, though not identical with, the ooze 

 which is now forming on the floor of the Atlantic, was deposited; 



