406 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [April 5, 



Newbury *, Reading f, near Maidenhead J, Chesham $, Hatfield J, 

 and Northaw J, and at Charlton, besides very many other places. 



At Alum Bay there are some very large roundish flints at or near 

 the junction of the Chalk and the Eeading Beds, sometimes, indeed, 

 included in the pipes of the latter; and in the new railway- cutting 

 just south of Brading station, near the other end of the island, the 

 same thing occurs. As far as I know, the layers of flint in the Chalk 

 are for the most part more or less tabular, and where not so, the 

 nodules are not of this great size ; and I should not be surprised if in 

 these two places, some eighteen miles apart, the Eeading Beds rest 

 on the same bed of the Chalk. This notion, however, would hardly 

 have entered into my head were it not that I had already found 

 that a like thing occurs over a small area in East Kent, as shown in 

 one of the foregoing papers (p. 398). At Whitecliff Bay the junc- 

 tion was quite hidden at the time of both my visits. 



Of course I do not mean to deny that there may have been 

 very large denudation of the Chalk before the deposition of the Ter- 

 tiary beds; indeed, as far as we can tell at present, there must have 

 been (see p. 397) ; but I have never seen, in any of the great junction- 

 sections, any proof of unconformity. A shght unevenness of surface 

 of the Chalk would be almost whoUj^ destroyed by the formation of 

 the far more irregular surfaces of pipes. 



Reconstructed ChalTc. — At the foot of the northern flank of the 

 Chalk Downs there may sometimes be seen a bed, a few feet thick, 

 made up of pieces of chalk and flints cemented together into a hard 

 mass, as at the western end of Afton Down and both ends of Motte- 

 stone Down. At the foot of Bembridge Down I saw two small pits 

 in the mottled plastic clay of the Eeading Beds, which was capped 

 by chalk-rubble, compact enough to be mistaken for Chalk itself. 



Summary. --This, paper is not meant to be a full account of the 

 Chalk of the Isle of Wight, for I have simply written it as a supple- 

 ment to what others have observed before, and the points to which I 

 have drawn attention are : — 



1. Whether the Chloritic Marl does not belong to the Upper 

 Greensand rather than to the Chalk. 



2. That there is a fairly exact line of division between the Chalk- 

 with-flints and the Chalk-without-flints ; and that this division is 

 marked in the Isle of Wight, as more clearly in Oxfordshire, Berk- 

 shire, &c.§, by the occurrence of a thin and peculiar bed, of a cream- 

 colour, hard, with irregular-shaped nodules (mostly green-coated), 

 and with its top well defined, whilst beloAv it passes into ordinary 

 Chalk ; and that here there is generally a thin layer of dark clay a 

 little above it. It is to be remarked also that the lowermost part of 

 the highest member of the Chalk contains comparatively few flints. 



3. That there is no proof that the Eeading Beds rest on a worn 

 surface of the Chalk; but that the very irregular junction of the 

 two is owing rather to the formation of pipes after the deposition of 

 the former. 



■* See Geological -Sm'vey Memoirs, on Sheet 12, p. 21. 



t Ibid, Sheet 13, pp. 38-40. J Ibid. Sheet 7, pp. 44, 39, 22, 30. 



§ Geological-Survey Memoii's, on Sheet 13, pp. 20, 21, and on Sheet?, pp. 5-8. 



