Ch. XXI.] CHALK ESCARPMENTS ONCE SEA-CLIFFS. 291 



valley excavated chiefly out of the argillaceous or marly bed, 

 termed Gault (No. 2). The escarpment is continuous along the 

 southern termination of the North Downs, and the reader may 

 trace it from the sea at Folkstone, westward to Guildford and 

 the neighbourhood of Petersfield, and from thence to the ter- 

 mination of the South Downs at Beachy Head. In this preci- 

 pice or steep slope the strata are cut off abruptly, and it is 

 evident that they must originally have extended farther. In 

 the accompanying wood-cut (No. 65), part of the escarpment 

 of the South Downs is faithfully represented, where the denu- 

 dation at the base of the declivity has been somewhat more 

 extensive than usual, in consequence of the upper and lower 

 green-sand being formed of very incoherent materials, the 

 former, indeed, being extremely thin and almost wanting. 



The geologist cannot fail to recognize in this view the exact 

 likeness of a sea-cliff, and if he turns and looks in an opposite 

 direction, or eastward, towards Beachy Head, he will see the 

 same line of height prolonged. Even those who are not 

 accustomed to speculate on the former changes which the sur- 

 face has undergone, may fancy the broad and level plain to 

 resemble the flat sands which were laid dry by the receding 

 tide, and the different projecting masses of chalk to be the 

 headlands of a coast which separated the different bays from 

 each other. 



No. 66. 



Chalk escarpment as seen from the hill above Steyning, Sussex. The castle and village of 

 Br amber in the fore-ground. 



Lower terrace offircstone. We have said that the upper 



U2 



