﻿1861.] 



WHITAXER — tJHAIK-ROCK OF BERKS, EXC. 



169 



flints below the rock. Of these I saw but two ; and in each the flint- 

 nodules were widely separated : it is possible that here also there 

 may be a second bed of the "rock" lower down. Besides the sections 

 that I saw, I also often heard of the occurrence of this bed in well- 

 sinking. Where it is thick, the well-sinkers are obliged to blast it, 

 on account of its hardness. 



"Where there are good clear sections, as near Henley, its upper 

 boundary will be seen to be sharply defined, the lower one not ; so 

 that I should take it to belong to the Lower rather than to the Upper 

 Chalk. The few fossils that have been found in it bear out this 

 view. 



In the parts of the chalk-country of Surrey and Kent known to 

 me, I have not noticed the Chalk-rock ; but my friend and colleague 

 Mr. Drew tells me that he has seen, in the former county, a bed 

 that seems to be like the Chalk-rock of Bucks, Berks, &c, and in 

 the same position. It may be seen on the flank of the chalk-escarp- 

 ment in the large quarries near Guildford, and in others between 

 Dorking and Beigate (north of the word " Betchworth " on the 

 Ordnance Map), where it is about 25 feet thick ; and also in the 

 valley along which the Caterham Branch-Railway runs, at the 

 Bose and Crown, about four miles north of the escarpment. The 

 following section taken at this last place has been given me by Mr. 

 Drew : — 



Reconstructed Chalk 4 or 5 ft. 



Chalk with flints about 25 „ 



Chalk with nodular structure and a few scattered 



From the above, it is clear that the bed is very thick about 

 here*. 



Prom the account of the chalk-cliffs near Dover, given by Mr. W. 

 Phillips, in the 'Transactions' of the Society f, I cannot clearly 

 make out its presence there. If it be present, it must be in great 

 thickness. 



The " Chalk-rock," should it prove to be the topmost bed of the 

 Lower Chalk, as it is in the counties of Berks, Oxon, and Bucks, must 

 have some influence on our notions as to the extent of country taken 

 up by that division of the Chalk. In the above-named counties the 

 Lower Chalk forms nearly the whole of the great escarpment, not 

 being covered by the Chalk- with-flints until within a short distance 

 from the top, except at the highest points of the range ; runs along 

 the main valleys for eight, ten, or twelve miles from the escarpment; 

 and, according to well-sections in brick-yards, is but from 40 to 80 



* Mr. Drew has lately revisited the chalk-country between Earnham and 

 Guildford, and he tells me that the Chalk-rock is about 25 feet thick in that 

 neighbourhood also. 



t 1st Series, vol. v. p. 16, &c. 



flints (Chalk-rock?) 

 Chalk without flints . . 



25 

 25 



