484 Whitoker — On Suhaerial Denudation. 



the winding ridge, and say how like it is to many a coast with its 

 succession of capes and coves ; even so distinguished a writer as 

 Sir C. Lyell remarking that " the geologist cannot fail to recognise 

 in this view (of part of the South Downs) the exact likeness of a 

 sea-cliff." ' And truly it is so ; but let us examine this likeness 

 more closely, and it will be seen that the argument founded on it, 

 plausible enough on the surface, is superficial only, and fails utterly 

 when rigorously tested. 



For this purpose let us place ourselves at some spot whence a 

 large extent of these hills may be seen. None perhaps can be 

 better than the hill crowned by Tottemhoe Camp, in Bedfordshire, 

 a projecting spur of the lower ridge of the Chalk (for there are two 

 escarpments in that neighbourhood, one formed by the Chalk Marl 

 and the bottom part of the flintless Chalk ; the other and larger by 

 the mass of the latter and the bottom part of the Chalk- with-flints). 

 Thence let us look eastward southward and westward along the 

 higher range, of which a long expanse unfolds itself to the view, 

 across the Thames even to the " White Horse Hill " in distant 

 Berkshire. The screen of even-topped combe-cut hills, shutting off 

 all view beyond, with its succession of swelling headlands and in- 

 curved bays, at once impresses the mind with the notion of an old 

 coast-line, and but little imagination is needed to picture the sea 

 beating furiously against the jutting capes, or rippling gently up 

 the sheltered hollows. 



But having indulged in a very pleasant day-dream, and transported 

 ourselves for the time to Dover cliffs, Beachy Head, or the great 

 Chalk buttresses of the Isle of Wight, let iis descend to sober prose 

 and our mental photograph will quickly fade, and soon be but " the 

 baseless fabric of a vision, leaving not a wreck behind." Eeason 

 asks what coast is this ridge like ? it is not enough that it should be 

 like a coast, but it should be like a Chalk-coast: "it is not a mere 

 resemblance that should correlate different things ; there should 

 be a specific character in everything that is to be generalised." ^ 

 The answer comes at once : it is like a coast along rocks of different 

 hardness (the softer yielding to form bays, the harder resisting to 

 form headlands), and not like one along a rock of much the^same 

 nature throughout — it is not like a Chalk-coast. 



Now let us examine the great escarpment more closely. Firstly, 

 we shall find that at its foot there are powerful ever-flowing springs, 

 thrown out generally at the out-crop of the Totternhoe stone,^ 

 which of course contain much carbonate of lime, as is shown by 

 the not uncommon occurrence, further down the streams, of twigs 

 thickly encrusted. Such constant taking away of matter from the 

 Chalk must wear away that rock ; and, given unlimited time, is enough 

 to get rid of any quantity of it. This is almost a mere matter of 

 multiplication ; if so many tons are carried away in a year, a 



1 Elements of Geology, Ed. 6, p. 359 (1865). Sir Charles now allows, however, 

 that the likeness is deceptive, see p. 449. 



2 Hutton, "Theory of the Earth," vol. i. p. 489. 



" The top hed of the Chalk Marl, see Quart. Journ. Geol. Soc, vol. xxii. p. 398. 



