102 GREY CHALK MARL, 



Crystals of pyrites terminating in the quadrangular pyramid of an oc- 

 tohedron, and disposed in irregular groups, are often imbedded in the casts 

 of ammonites, and other fossU remains ; and the marl pits at Hamsey, 

 contain masses of this mineral bearing the form of a species of Eschara, 

 somewhat resembling E.foliacea. 



3. Oxide of iron, in the state of a reddish brown powder, is frequent in 

 cavities of the marl, and has probably been produced by the decomposition 

 of iron pyrites ; the greater part of the marl fossils have acquired a fer- 

 ruginous colour from this mineral. 



4. Clay slate. The occurrence of this substance in the marl is clearly 

 accidental, having been derived from some regular bed of argillaceous slate 

 of anterior formation to the chalk marl. The only examples hitherto dis- 

 covered, were imbedded in the marl at Southerham Corner ; the largest 

 is about two inches square, and nearly half an inch thick: the edges are 

 sharp, and the specimen appears to have suffered but httle from attrition. 



Organic Remains. 



The grey chalk marl in its course through Sussex, is well characterized 

 by its organic remains, which differ both in their nature, and in the mode 

 of their preservation, from those either of the superincumbent bed of lower 

 chalk, or of the blue marl upon which it reposes. 



Numerous species of ammonites, nautili, and inocerami, are the most 

 common productions of the pits near Lewes, which also contain turri- 

 lites, scaphites, hamites, &c. These remains of testacea very rarely exhibit 

 any vestige of their original sheUy covering, but consist of casts of indu- 

 rated argillaceous limestone, of an ochraceous or a ferruginous colour, 

 more or less distorted by compression. 



1. Wood. The existence of fossil wood in the chalk formation has 

 been much questioned by some geologists, but the fact is indisputable, as 

 numerous examples in my collection satisfactorily prove. It is of a dark 

 brown colour inclining to black, and when first collected, very distinctly 



