J. S. GARDNER ON THE LOWER LONDON TERTIARIES. 



201 



Dover Kailway, and appears to be light- 

 coloured sea-sand, with considerable cohe- 

 sion, about 60 feet thick and destitute of 

 fossils. The few localities in East Kent 

 described by Prestwich and the Survey in 

 which fossils have been found do not seem 

 to differ in any important respect from the 

 section at Heme Bay and Pegwell Bay, and 

 need not, therefore, be further alluded to 

 here. The fossiliferous divisions of the 

 formation can in fact be perfectly studied 

 along the coast, which presents by far the 

 most perfect and accessible, as well as the 

 most typical sections (fig. 2). 



The Herne-Bay section terminates at the 

 Beculvers, and, as restricted by Prestwich 

 and the Survey, only exposes some 20 feet 

 of Thanet Beds — Pegwell Bay, however, for- 

 tunately supplying a continuous section 

 through the remaining thickness to the 

 Chalk (fig. 5). The position of the lowest 

 Beculver bed can be accurately determined 

 palaeontologically in the Pegwell section ; 

 but to make it quite certain, the measure 

 of its exact height above the Chalk, which 

 is about 70 feet, is given in a well sunk at 

 Reculver. 



The Thanet Beds rest conformably, as it 

 is called*, on the Chalk at Pegwell Bay, 

 with at first a dip of about 5° S. 



The base rests on a great tabular layer of 

 flint, and is full of the usual unworn green- 

 coated flints. It is now generally recognized 

 that these flints have been dissolved out of 

 the Chalk by solvent action, like that which 

 produced the piping in chalk subsequent to 

 its upheaval f ; and the present upper surface 

 of the Chalk is therefore not actually the 

 same as that on which the first Eocene mud 



* Even the highest Chalk must have been greatly 

 denuded, as it could hardly have risen to the surface 

 before it was compressed into a solid rock without 

 being covered with something capable of resisting 

 wave-action. There is at least no instance of any 

 such deposit having been preserved as a surface 

 deposit in any Atlantic isles that have been up- 

 heaved. The Thanet Sands are as little conform- 

 able, and had as little to do with the Chalk as the 

 Goodwin Sands. 



t Whitaker, Quart. Journ. Geol. Soc. I. c. pp. 

 406, 407. 



*l 



V : rill' 



bd i=- 



& 



5 "8? 



to 



i 



o 



N 





CD 



B 



1 



g 



