192 NORTH STAFFORDSHIRE COAL FOSSILS. 



overlaid by another marine deposit ; and also suggests 

 whether the phenomena cannot be accounted for by sup- 

 posing that the coal-measures were accumulated in an 

 estuary, into which flowed a large river, subject to occa- 

 sional flushes of water charged with the testacea and the 

 vegetation of the adjacent districts.* At present, the 

 facts adduced are too scanty to warrant the conclusion 

 that the marine beds of this coalfield are correlative to 

 those of other coalfields. 



The organic remains of the lower thick measures con- 

 sist chiefly of plants and mollusca ; fish remains are more 

 rare. At a short distance below the Gin mine or Golden 

 twist coal, and underlying a sandy rock, there is a bed 

 of dark shale which contains an interesting collection of 

 marine fossils. In addition to those found in the bay 

 coal, it contains a large species of Nautilus, two or more 

 of Chonetes, together with Goniatites, Nacula, Axinus, and 

 other forms. It is somewhat remarkable that these fossils 

 appear to occupy different levels in the deposit to which 

 they are confined, and are separated from each other by 

 distinct horizons. Thus, Lingula is confined to the upper 

 portion of the bed in question. This mode of occurrence 

 is interesting, and well worth further consideration. 



At a distance of about thirty yards below the Gin 

 mine, there is a third marine bed which contains fewer 

 fossils both in regard to species and individuals. They 

 are much more worn than those in the upper bed. The 

 Cockshead ironstone, at Adderley Green, occurs in irre- 

 gular bands and frequently assumes a nodular character. 



* Trans. Geol. Soc., 2nd Series, vol. v., p. 464. 



