CHALK ESCARPMENTS.

359

Ch. XIX.]

hinted by the author above mentioned, that great amount of ele-vation towards the centre of the Weald district gave rise to trans-verse fissures. And as the longitudinal valleys were connectedwith that linear movement which caused the anticlinal lines runningeast and west, so the cross fissures might have been occasioned bythe intensity of the upheaving force towards the centre of the line.

But before treating of the manner in which the upheaving move-ment may have acted, I shall endeavour to make the reader moreintimately acquainted with the leading geographical features of thedistrict, so far as they are of geological interest.

In whatever direction we travel from the tertiary strata of thebasins of London and Hampshire towards the valley of the Weald,we first ascend a slope of white chalk, with flints, and then findourselves on the summit of a declivity consisting, for the most part,of different members of the chalk formation ; below which theUpper Greensand, and sometimes, also, the Gault, crop out. Thissteep declivity is the great escarpment of the chalk before mentioned,which overhangs a valley excavated chiefly out of the argillaceousor marly bed, termed Gault (No. 3.). The escarpment is continuousalong the southern termination of the North Downs, and may betraced from the sea, at Folkestone , westward to Guildford and theneighbourhood of Petersfield , and from thence to the termination ofthe South Downs at Beachy Head. In this precipice or steep slopethe strata are cut oif abruptly, and it is evident that they mustoriginally have extended farther. In the wood-cut (fig. 358. p. 358.)part of the escarpment of the South Downs is faithfully represented,where the denudation at the base of the declivity has been some-what more extensive than usual, in consequence of the Upper andLower Greensand being formed of very incoherent materials, theformer, indeed, being extremely thin and almost wanting.

The geologist cannot fail to recognise in this view the exactlikeness of a sea-cliff; and if he turns and looks in an oppositedirection, or eastward, towards Beachy Head (see fig. 359.), he will

Fig. 359.

Chalk escarpment, as seen from the hill above Steyning , Sussex. The castle and villageof Bramber in the foreground.

see the same line of heights prolonged. Even those who are notaccustomed to speculate on the former changes which the surface hasundergone may fancy the broad and level plain to resemble the flatsands which were laid dry by the receding tide, and the different