190 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [Feb. 10, 



Folkestone, in the limits between 30 feet and 70 feet above the top 

 of the Lower Ureensand, and still at some distance beneath the 

 Upper Greensand, can be found all the Ammonites and Nautili given 

 in the previous list, together with the Belemnites and the whole of 

 the other species mentioned as pecuhar to the Red Chalk, excepting 

 only the Amorphozoa, the Corals, Bourgueticrinus rugosus, Tory no- 

 crynus canon, Pseudodiadema Brongniarti, P. ornatum, JSalenia 

 Wiltshirei, Holaster suhorhicularis, Serpula cristata, S. rustica, Te- 

 rehratula caj^illata, Mhynchonella sulcata, and Spondylus striatus. 

 The presence of the varietal form of Inoceramus sulcatus (which I 

 have ventured to name suhsulcatus) and the extreme rarity or total 

 absence of Inoceramus concentricus are marked features in the 

 upper part of the Gault at Folkestone, define a particular zone, and 

 correspond with what is observed at Hunstanton. That a few 

 species may not be common to both localities is to be expected, 

 seeing that the two places are 150 miles apart, and that the strata 

 must have been deposited at those spots under somewhat different 

 conditions, and in a manner which might not be equally favourable 

 to certain forms of life. 



According to the statements of persons resident in the district 

 adjoining Hunstanton, and who have seen inland sections opened 

 for agricultural purposes, the blue Gault with its characteristic 

 Belemnites rests on the Cars tone at FHtcham, 10 miles south of 

 Hunstanton, but rather nearer the latter place, and still close 

 to Flitcham, a red clay occurs immediately under the white chalk, 

 thus connecting the Blue Gault with the '*Red Chalk." From 

 Sandringham, 8 miles south of Hunstanton, the outcrop of the Red 

 Chalk can be traced without difficulty and continuously to its last 

 appearance on the surface of the ground near the Lighthouse. 



The lithological difference between the Red Chalk with its stony 

 hardness and accompanying minute pebbles, and the Blue Gault 

 with its soft clay, is no argument against the two being geologically 

 equivalent ; for as great a dissimilarity exists in the Carstone. At 

 Hunstanton the Carstone stratum is dark yellow and very full of 

 pebbles ; at Sandringham, at the corresponduig portion, it is a pure 

 white sand. But the evidence which organic remains and local 

 position supply in favour of the Red Chalk being a northern equiva- 

 lent of the Gault of Kent is singularly strengthened by testimony of 

 quite another kind. Chemical analysis shows that the strong con- 

 trast in colour which exists in the case of the Red Chalk and the 

 Gault, and which apparently places them apart, is a combining link 

 between them, the upper part of the Kentish Gault being as ferru- 

 ginous (only under another aspect) as the Red Chalk itself. This 

 fact, for which I am indebted to Mr. David Forbes, is described in the 

 following extract from a letter written by that gentleman to myself, 

 referring to a comparative chemical analysis of the Gault and Red 

 Chalk, the part of the Gault selected for the experiment having 

 been taken from the Folkestone beds, about 50 or 60 feet above the 

 top of the Lower Greensand, where, for some vertical distance, the 

 deposit is very homogeneous. 



