HARDWICKE'S SCIENCE-GOSSIP. 



61 



sections — that is, between Compton and Blackgang 

 Chines ; between these points all the beautiful 

 Atherfield fossils have been found. Hard work is 

 indispensable for extracting organic remains from the 

 rock, some of the concretionary limestones being of 

 the hardest texture. Referring to the monograph of 

 Professor E. Forbes,* on the Atherfield series, it will 

 be found he estimates the thickness of the entire 

 formation at 843 feet, dividing the whole into sixty- 

 three substrata, on account either of their fossil 

 contents or difference in composition. Mantell 

 statesf tnat > although the sections exposed are 

 vertical, they are in an oblique direction to the plane 

 of stratification, and, from the slight angle at which 

 the strata dip to the N.E., the cliffs as far as Black- 

 gang are composed of Greensand deposits. 



For full details of the substrata we must refer the 

 reader to the monograph of Professor E. Forbes, 

 and to Dr. Fitton's memoir, "Geological Journal," 

 vol. i., p. 179. Here we can deal only with the 



(5.) Further deposit of blue clays with lobster, etc. 

 (fig. 1). 



(6.) Zone of Terebratula, full of fossils. 



(7.) Band of Gryphese and Scaphites. 



It is in these lower beds the collector must search, 

 leaving the ferruginous sands as entirely unproductive. 

 A large geological hammer and a couple of strong 

 chisels are indispensable ; even with these tools it 

 will be found hard work extracting fossils. The best 

 place for descending the cliff is a path a few paces 

 beyond the flag-staff which indicates the coast-guard 

 station ; this is indeed almost the only safe place 

 where a descent can be made. Supposing the tide to 

 be receding, it will be advisable to walk a short 

 distance round Atherfield Point to the westward ; 

 here we at once see several feet at the base of the 

 cliff of a brown colour, numerous lumps of the same 

 being strewn along the beach ; from these lumps 

 well-preserved fossils may be obtained, the section 

 corresponding to Nos. 1 and 2 of the above list. 



Fig. 46. — Grevillia anceps. 



Fig. 47. — Meyeria Vectensis, McCoy. 



'fossiliferous bands, which are, after all, those of the 

 greatest interest to the geological student. It is after 

 high tides and heavy seas that the cliffs are most 

 exposed, and it is better to fix a day so that the tide 

 shall be on the ebb during the five or six hours it is 

 is intended to study the rocks. The whole of the 

 Atherfield Greensand is divided into three main 

 divisions, in the lowest of which the fossils chiefly 

 occur. The substrata of the lower section care thus 

 given by Mantell — 



(1.) Lowest Greensand clay, brown, 3 feet thick. 

 (2.) Perna Mulleii beds, 2 feet. 

 (3.) Atherfield clay strata, 100 feet, abound in 

 fossils in lower portion, few in middle, a small 

 species of lobster in upper part. This clay 

 is blue. 

 (4.) Cracker rocks ; beds of sandy clay with two 

 bands of concretionary masses of hard calci- 

 ferous sandstone. 



Palaeont. Soc. 



f " Geology of the Isle of Wight." 



With regard to the blocks which lie on the beach, 

 I have found that the best fossils are usually visible 

 on the outside ; nevertheless, by splitting up such 

 blocks, we frequently obtain different mollusca. 

 Perna Mullet i (Desh.) is the characteristic fossil to be 

 met with, excessively difficult to extract on account 

 of the protruding valve, which, in five cases out of 

 six, snaps off. Gryphea sinuata abounds everywhere, 

 and is easily obtained ; also Terebratula sella (Sow.), 

 Rhynconella (sp.), Panopcea plicata (Sow.), Cordis 

 corrugata, Venus substriata, Pecten quinquecostatus 

 (Sow.), Trigonia caudata (Agass.), Trigonia dcedalia, 

 Area Raulini, Nucula seap/ia, A T atica rotundata, and 

 many other well-preserved shells. In one day I defy 

 anybody to collect even half these fossils ; in a fort- 

 night one might procure these and many others. The 

 loose blue clays will easily be identified as we walk 

 eastward from Atherfield Point ; here it is that the 

 small lobster, a species of Astacus, is to be found. 

 After rain I have found several specimens lying 

 washed out of the saponaceous clay. Larger Crus- 



