372 G. E. Dibley— Chalk Rock in North Kent. 



thickness and altogether of smaller importance than tlie rest. The 

 following table sets forth the names which I would adopt for these 

 stages, and the zones which they comprise: — 



Stages. Zones. 



Danian ' Nautilus danicus. 



Belemnitella inucronata . 



Actinocamax quadratus. 



Off aster pilula. 



Marsu'pites. 

 Senonian \ Micraster coranguinwn. 



M. decipiens. 



Holaster planus. 



Terebratulina lata. 



Rhynchonella Cuvieri. 

 Cenomanlan ] Holaster subglohosns. 

 { Schloenbaciiia varians. 



Campanian 



TURONIAN 



I 



V. — Note on the Chalk Rock in jS'orth Kent. 



By G. E. Dibley, F.G.S. 



N the early spring of 1910, while collecting in the Chalk quarry at 

 Borstal,^ I found in a loose piece of chalk an impression of a small 

 Gasteropod shell which probably belongs to the genus Lamptisia. 

 Shortly afterwards, while at the Borstal Manor Quarry, a workman 

 brought me another small Gasteropod, which has since been identified 

 as Turho geinitzi, Woods. Both specimens were preserved as casts, 

 showing part of the external ornament from near the apex to the 

 basal whorl. Part of the zone of Holaster planus is exposed in the 

 quarry, but the locality is not included in my previous list of 

 exposures in the neighbourhood. The occurrence of these Gasteropods 

 at such an horizon was almost conclusive evidence of the presence of 

 the Reussiamim fauna, so I again visited the quarry, in company with 

 my wife, with a view to discovering the exact position at which these 

 fossils occurred. 



The lithological character of a certain bed of Chalk at Borstal is 

 exactly the same as that on the other side of the Medway, being 

 exposed in Messrs. Martin & Earl's quarry at Wickham (No. 2) - 

 and at Messrs. Trechmann's quarry at Cuxton (No. 4). A small block 

 from this bed, about the size of a cubic foot, would be found to contain 

 irregular patches deeply iron-stained and of a nodular and fibrous 

 character, the remainder being soft and gritty. I had for some time 

 been familiar with its distinctive lithological features, but until that 

 time had never succeeded in obtaining any fossils from it. A more 

 detailed search at Wickham yielded a small indeterminable Gasteropod 

 cast, and a specimen of Dentalium turoniense, Woods. 



In the spring of this year we again visited the Borstal Quarry, 

 which had been unworked since December, and during five hours' 

 search came across the rich molluscan fauna that characterizes the 

 'Chalk Rock'. This was in the bed of Chalk, about 5 feet in 



^ Proc. Geol. Assoc, vol. xvi, p. 484, 1900. 



- These numbers refer to the list of exposures m (1). 



