﻿Vol. 66.] DENUDATION OF THE WESTERN END OE THE WEALD. 643 



II. Review of Existing Hypotheses. 



(A) General Evidence in favour of a former Plain 

 (Marine or Subaerial). 



(i) The coincidence of the highest levels throughout 

 the area. — It is upon the evidence for this coincidence that 

 Ramsay and Topley mainly depend ; indeed it may safely be said 

 that, in its absence, no one would have put forward a theory of 

 planation at all : it is a different matter, however, to assert that 

 the evidence can lead to no other conclusion. Following Topley 

 (26, p. 240), I shall examine these coincidences along two lines, 

 longitudinal and transverse. In the longitudinal series the Chalk 

 Downs offer the most important evidence, and for that reason I give 

 diagrams (figs. 1, 2, & 3, p. 642) showing their principal elevations, 

 the measurements of which, taken from the most recent maps of the 

 Ordnance Survey, differ somewhat from those of the old Survey 

 used by Topley, but not to any important extent. In these diagrams- 

 a greatly exaggerated vertical scale has been used, in order to give 

 prominence to certain features which would otherwise be obscure ; 

 but in spite of this it has been found possible to join together the 

 principal summits by a line (dotted) which is almost straight. In 

 figs. 1 & 2 I have also introduced a fine line showing a smoothed 

 curve of the Downs as a whole, with their relation to the river- 

 valleys ; but, in the case of the South Downs (fig. 3), the numerous- 

 embay ments made this practically impossible. 



Topley claims that his figures (26, pp. 240-41) show a general 

 fall from west to east. This may be true of the South Downs, 

 although the fall is very small as far east as Ditchling Beacon, and 

 beyond that it is due in some measure to the curve of the escarp- 

 ment line towards the south ; but in the North Downs this fall 

 towards the east is certainly not conspicuous, even if it has any 

 existence at all. In the first place, it is noticeable that Topley goes- 

 far to the west of the Wealden area for his starting-point, and that 

 if he had done the same with the South Downs he would have 

 arrived at very different results. Inkpen Beacon, with which he 

 commences, rises to 1011 feet O.D., but the highest point in the 

 Downs bounding the Weald is Botley Hill (882 feet O.D.). Between 

 these two hills, nearly 70 miles apart, there are few points which 

 rise above 800 feet, and for a distance of 60 miles absolutely 

 none at all. Beyond Bofrley Hill (fig. 2) the fall to the east 

 is evident enough, but on its other side (fig. 1), if we confine our- 

 selves to the Wealden area, the diagrams suggest a similar fall 



[Note on figs. 1-3, p. 642. — Figs. 1 & 2 are a diagrammatic elevation of the 

 North Downs. The actual summit of the Downs, omitting minor irregularities, 

 is represented by a fine line, and the theoretical summit of the plain by a dotted 

 line. Fig. 3 is a similar elevation of the South Downs : owing to the greater 

 unevenness of the crest of the escarpment and the complications introduced 

 by the deep embayments, the actual summit-line is omitted.] 



