GATTLT AND UPPER CHALK NEAR FOLKESTONE. 433 



related with my bed VI. of Holaster subglobosus, although much 

 narrowed. 



In his " Turonien " M. Hebert makes one general " assise," sub- 

 divided into four zones ; the two lower, of Belemnites plenus and 

 Inoceramus labiatas, are equal to my zones of the same names. 



His Echinoconus-sabrotundus and Holaster -cor-avium zones equal 

 my zoue of Echinoconus subrotundus and Terebratulina gracilis, bed 

 IX., together. Prof. Hebert*, in his paper entitled " Comparaison 

 de la Craie des Cotes d'Angleterre avec celle de Prance," considers 

 the Upper Greensand, Chalk Marl, and Grey Chalk of the coast 

 section at Lydden Spout to be equivalent to the glauconitic marl of 

 the Trench coast, and the chalk without flints, beds VII., VIII., 

 and IX. of this section, to the lower and middle zone of Chalk with 

 Inoceramus labiatus (?). 



In the Pas de Calais M. Hebert divides the Chalk Marl and Grey 

 Chalk collectively into four parts, i. e. : — 



1. Niveau a Plocoscypkia mceandri7ia=my beds 1 and 2. 



2. Niveau a A. varians=my bed 3. 



3. Niveau a A. rhotomagensis—vay bed 4. 



4. Niveau a Belemnites ple7itis=my beds 5, 6, and 7. 



The lists of fossils recorded as found by himf in this area are, in the 

 main, the same as I have met with at Folkestone and Lydden Spout. 



Bed I. (Chalk Marl). 



Immediately resting upon the Upper Gault (bed XL) is a dark 

 greenish sand, calcareous and clayey, poor in organic remains. The 

 green grains become thinner and fewer about 16 feet up in the de- 

 posit, where it is less sandy and the deposit partakes more of the 

 character of marl. 



On the hill beneath the Martello Tower No. III. quantities of cream- 

 coloured concretions were met with. This formation can be seen in 

 situ near Copt Point, Folkestone, reposing more or less conformably 

 upon the gault. Short pipings of this dark green sand extend only 

 for about 3 or 4 inches into the gault beneath. 



The total thickness of this bed near Copt Point in the hill below 

 the Martello Tower III., measured from the top of bed XL of the 

 Upper Gault, where the green pipings are first observed, up to the 

 base of the whitish marly deposit sometimes called chloritic or glau- 

 conitic marl, is about 14 feet ; but it is extremely difficult to obtain 

 an accurate measurement. It has usually been roughly estimated as 

 having a thickness of 15 feet in East- Wear Bay. Mr. Topley con- 

 siders it not to be thinner than 20 feet here. 



This dark sandy marl, commonly called Upper Greensand, thins 

 out gradually to the north-west of Folkestone, where only a thin 

 seam of chloritic marl reposes on the gault. Mr. Topley statest that 

 " at the foot of Castle Hill it is exposed in a road-cutting, where it 



* Bull. Soc. Geol. France, 3 e ser. t. ii. pp. 416-428. 



t ' La zone a Belemnites plenus,' C. Barrois : Lille, 1875.. 



f ' Geology of the Weald,' W. Topley, p. 152. 



