O. Dowker — On the Chalk of Kent. 471 



Lyme Ebgis. Grbnelle, Paris. 



Chalk, numerous flints 50 Chalk, with flints 1148 



Do. flints not so numerous 50 Lower Chalk 246 



Without flint 40 



Ditto, green grains 25 1394 



165 



And the section at Harwich — Chalk, with flints 690 



„ „ Chalk, without flints 198 



888 



It will be seen from the foregoing sections that the Upper Chalk 

 prevails at Norwich, Isle of Wight, Paris, and Harwich, while the 

 Lower Chalk at Dover, Calais, and Diss in Norfolk, which latter 

 section presents a remarkable exception to the Norfolk Chalk, and 

 appears to correspond with that of Margate. The absence of flint 

 in the Chalk, or at least flint in tabular layers, may be owing to 

 some lithological character of the Chalk, as soft Marly Chalk is 

 generally destitute of flint. Mr. Tate, in a paper read before the 

 Geological Society in 1864,^ described the Upper Cretaceous beds of Ire- 

 land as equivalents of the Norwich Chalk, though they differ so much 

 in lithological appearance that Conybeare referred them to the Lower 

 Chalk. I observed last summer, during a visit to the Isle of Wight, 

 that the Upper Beds of Chalk, at the junction with the Plastic Clay 

 at Alum and White Cliff Bay, had a more Marly and soft appearance, 

 and I obtained a few fossils corresponding with those from Margate. 

 The Chalk at Gravesend and Northfleet though possessing more 

 flints than the Upper Beds of the Isle of Thanet have many fossils in 

 common, but on the whole I should consider it more like the Upper 

 Beds of the Kamsgate Chalk- How far the Thanet beds may rest 

 conformably on the Chalk it is difficult to determine, since we have 

 no continuous sections, but the denudation of the Chalk, previous to 

 the deposition of the latter, shows such an even junction in all the 

 sections I have had the opportunity of observing, that it would seem 

 to have been more a sub-marine than a subaerial action. At Alum 

 Bay the junction of the Eeading beds with the Chalk is even, (if we 

 except the sand pipes) and marked by rounded pebbles in a ferrugi- 

 nous sand. In East Kent the fossils derived from the Chalk in the 

 sand at the junction are characteristic of the upper division, Anan- 

 chytes ovatus, yox. pyramidatus; and Galerites alhogalerus, var. tumidior 

 being very constant. 



Of the fossils from the Margate Chalk I have several specimens 

 of large Ammonites, one nearly three feet in diameter. It corre- 

 sponds nearly with the Ammonites l&ptophyllus, only it possesses 

 no ribs or undulations on the surface. Another specimen resembles 

 Ammonites Lewesiensis, figured in the Palaeontographical Monograph. 

 I have also casts in flint of two other species. 



A small Belemnite is very abundant ; also a small distorted Ostrea. 

 The fossils have been collected from the following localities : — Mar- 

 gate (I am indebted to Mr. Wetherell for several small fossils from this 

 1 Quart. Journ. Geol. Soc, vol. xxi., p. 19. 



