292 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



a much greater diversity is observable between the sections of this 

 island and those of Kent*, and still more remarkable variation in the 

 interior of France. 



The following are the divisions which I have adopted in my arrange- 

 ment of the strata : — 



A. — The lowest division, consisting only of two remarkable fos- 

 siliferous beds, Nos. 1 and 2, occurs immediately above the Wealden 

 clay. From the abundance of Ferna Mulleti in both of these beds, 

 a species not found in any other part of the section, I have named 

 this group from that fossil. 



B. — T\\e Atherfield clay, No. 3, possessing many of the properties 

 of fuller's earth. 



C. — Sand and clay, Nos. 4 to 10, including two prominent ranges 

 of fossiliferous nodules (pa and 55) which form a projection on the 

 coast called the " Crackers." 



D. — A series of sands and sandy clay — green, ferruginous, and 

 brown, comprehending several important groups of fossils, extends 

 from the Crackers group (4) to No. 45, at the top of the cascade of 

 Black-Gang Chine ; subdivided chiefly by the fossiliferous clay and 

 sands (24 and 25), which rise on the shore between Whale and 

 Walpen Chines. 



It is to this central portion of the section that the term " Green- 

 sand" may be emphatically applied, many of the beds being tinged 

 by green silicate of iron ; but a large part consists of brown and fer- 

 ruginous sand mixed with clay, for which *' indurated mud'' is pro- 

 bably the best name. This series is fossiliferous throughout, and is 

 the chief abode of the genus Gryphcea, especially G. sinuata, a species 

 which, though frequent in the lowest beds 1 and 2, and dispersed also 

 throughout the present division, is here chiefly abundant in two sub- 

 ordinate groups — 11, 13, and 36, 37t. The genera Scaphites and 

 Crioceras are likewise confined to this division, the latter appearing 

 in numerous ranges. A large portion of this part of the series con- 

 tains oolitic iron in considerable quantity : and remains of Loncho- 

 pteris Mantellii, a fossil fern hitherto found only in the Wealden 

 group, have been detected by Mr. Morris in so many different places, 

 that it may be regarded as diffused throughout the whole division. 



E. — The two great beds of clay, Nos. 46 and 48, the first 60, the 

 latter 40 feet in thickness, form a mass of such importance, — though 

 in this case destitute of fossils, — that I would place them apart with 

 the intermediate bed of sand No. 47, as a separate division, the total 

 thickness of which is not much less than 120 feet. 



F. — The uppermost division is composed of sand, frequently white, 

 alternating with some clay, some beds of the former of great thickness, 

 but on this part of the coast containing few fossils, or none. This 

 division extends from the top of the great bed of clay No. 48, to the 

 bottom of the Gault above. 



* Geol. Soc. Proceedings, vol. iv. p. 396, and Geol. Journal, vol. i. p. 1 79, &c. 



t In the corresponding section on the west of Shanklin, another site of Gry- 

 pJiaa sinuata has been discovered by Messrs. Ibbetson and Forbes, in a still higher 

 part of the series, corresponding probably to No. 41 of the section near Atherfield. 



