﻿644 ME. H. BUEY ON THE DENUDATION OP [Nov. I9IO, 



towards the west, at any rate as far as Parnham. Before, however, 

 we conclude that the slopes thus indicated are due to warpings of a 

 former plain, we must examine carefully the effects of the change 

 of dip, which between Guildford and Parnham is very marked ; and 

 this may conveniently he deferred to a later stage of this paper. 



If we turn next from the Chalk to the Lower Greensand escarp- 

 ment, we again fail to find confirmation of Topley's contention. 

 Here also, it is true, there is a fall from west to east on the south 

 side of the central watershed, but not in a very convincing form. 

 The highest point is Blackdown (forming part of the watershed), 

 which reaches 912 feet O.D., and is therefore higher than any part 

 either of the North or the South Downs ; but to the east of that 

 hill there is not a single point rising above the 500-foot contour, so 

 that, even if marine planation is accepted, there is nothing here 

 which is high enough to be regarded as a remnant of the plain : and 

 I submit that this fall towards the east, to which Topley was 

 inclined to attach importance (26, p. 240, note), is more closely 

 connected with the diminution in hardness and thickness of the 

 Hythe Beds than with any tilting of a former plain. 



On the north side of the watershed Hindhead rises to 895 feetO.D. ; 

 some miles farther east are Pitch Hill (844 feet) and Holmbury Hill 

 (800 feet), both higher than the adjoining Downs, and then comes 

 Leith Hill (965 feet), the highest point in the series. It is only 

 when we pass beyond the Mole that any fall towards the east can 

 "be admitted, and even there it is by no means clear that the lowness 

 of the hills is a primitive feature. Since the Lower Greensand 

 strata vary much in character, it is conceivable that they may once 

 have been planed off to a fairly uniform level and then reduced 

 unevenly ; but, as evidence of planation, the hills of these strata are 

 obviously inferior to the Chalk Downs. 



Along the central axis Blackdown and Hindhead in the west rise 

 higher than any hills farther east ; but then there are no other 

 points of observation, with the exception of Crowborough Beacon, 

 which even approximate to the level of the Downs. Now Crow- 

 borough Beacon (792 feet CD.) clearly owes its elevation in large 

 measure to the upheaval of the Hastings Beds, the dip-slope of 

 which radiates out from it in every direction. If it were as high as, 

 or higher than, the Downs, or if any definite signs of planation were 

 shown, we might perhaps accept it as a relic of a marine or sub- 

 aerial plain, but as it stands I see no reason at all for doing so ; 

 indeed, assuming that a plain even existed, I doubt whether it was 

 low enough for any part of the Hastings Beds to be uncovered. 



We come next to the transverse series. Ramsay (21, 5th ed. 

 p. 341) describes the uplifted plain as ' slightly inclined from the 

 interior,' but his diagram (21, 5th ed. fig. 73, p. 343) leads us to 

 infer that he regarded the inclination as scarcely perceptible. Topley 

 is not quite consistent on this point : in one place (26, p. 274) he 

 says that the existing dip-slope roughly represents the slope of the 

 marine plain (a very doubtful proposition, since the dip-slope of 

 the Chalk might, and sometimes does, correspond to a pre-Eocene 



