Whitaker — On Subaeiial Denudation. 



489 



In Kent the Chalk escarpment and the Chalk cliff cut one another 

 obliquely, whilst at the western end ol the Isle of Wight the two 

 are for a wonder parallel ; but alas for the advocates of the marine 

 formation of escarpments ! this latter case in no way helps their 

 theory, for putting aside the consideration of the fact that the 

 cliff leaves the Chalk and turns southwards to cut through lower 

 beds, one can see at a glance that the formation of the cliff has in 

 great part destroyed the feature of the escarpment, of which only 

 the curved top remains, as shown in the section below. Moreover 



Fig. 3. — Section showing the relation of the Chalk cliff and the Chalk escarpment 

 s. in the Isle of "Wisrht. n. 



Scale ahout six inches to a mile. 



1. Lower Tertiary beds. 2. Chalk with many layers of flints. 3. Chalk with few flints. 



4. Chalk without flints. 5. Chalk Marl. 



6. Upper Greensand. 7. Gaiilt. x x. Sea-level. 



The broken lines show the form of the ground and the continuation of the beds, which must 



have existed before the sea-cliff was worn back into the escarpment, and which correspond to 



the same as they now exist in those parts away from the sea. 



The dotted lines show the further extension of the beds until cut off by the " plain of marine 

 denudation" made before the exposure of the land to subaerial actions. 



the sea has utterly destroyed the Chalk ridge between the Needles 

 and Handfast Point in Dorsetshire. Along all Chalk-coasts, indeed, 

 the antagonism of the two denuding powers is well shown, the 

 sharp cliffs cutting across the gently curved outlines of hill and 

 valley that have been caused by long continued subaerial actions, 

 the sea levelling what these have furrowed. 



Let us now turn to the Tertiary coast of Kent. The foreshore of 

 the Isle of Shejapey (and also of the greater part of the mainland 

 from Whitstable to beyond Heme Bay) consists of a plain of London 

 Clay sloping gently seawards. The cliffs are mostly sharp irregular 

 broken slopes, not altogether cut out by the sea, but formed by the 

 slipping downwards of masses of London Clay and of the overlying 

 Bagshot Sand and Drift gravel, which last two form a more vertical 

 ridge at the top of the slope. 



Now it is clear that the waves do not rush up to the top of the 

 cliff and bring down the clay sand etc., but that the fallen masses 

 owe their fall to frost, rain, and heat :. the heat of summer to dry up 

 the beds, and by shrinkage to form fissures down which the rain 

 may soak ; rain to soften and make slippery ; frost to divide mass 



