Ch. XXI.] 
DENUDATION OF WEALD VALLE V. 
293 
of the waves; its outcrop, therefore, is marked by a valley, the 
breadth of which is often increased by the loose incoherent 
nature of the uppermost beds of the lower green-sand, which 
lie next to it, and which have often been removed with equal 
facility. 
The formation last mentioned has been sometimes entirely 
smoothed off like the gault; but in those districts where chert, 
limestone, and other solid materials enter largely into its com- 
position, it forms a range of hills parallel to the chalk, which 
sometimes rival the escarpment of the chalk itself in height, or 
even surpass it, as in Leith Hill. This ridge often presents a 
steep escarpment towards the Weald clay which crops out from 
under it. (See the strong lines in diagram No. 63, p. 288.) 
The clay last mentioned forms, for the most part, a broad 
valley, separating the lower green-sand from the Hastings 
sands, or Forest ridge ; but where subordinate beds of sand- 
stone of a firmer texture occur, the uniformity of the plain is 
broken by waving irregularities and hillocks*. 
In the central region, or Forest ridge, the strata have been 
considerably disturbed and are greatly fractured and shifted. 
One fault is known where the vertical shift of a bed of 
calcareous grit is no less than 60 fathoms -f-. It must not be 
supposed that the anticlinal axis, which we have described as 
running through the centre of the weald, is by any means 
so simple as is usually represented in geological sections. 
There are, on the contrary, a series of anticlinal and synclinal | 
* Martin, Geol. of Western Sussex. Fitton, Geol. of Hastings, p. 31. 
f Fitton, ibid., p. 55. 
I We adopt this term, first used, we believe, by Professor Sedgwick ; its signi- 
fication will best be understood by reference to the accompanying diagram. 
No. 68. 
a } Anticlinal lines. b, Synclinal lines, 
