﻿CRETACEOUS BRACHIOPODA. 



19 



the Upper Greensand, the Chalk-mar], and the lower part of the Lower Chalk of 

 England (?). 



The Red Chalk of Hunstanton has been considered by some geologists to represent 

 the Upper Gault, and at any rate it seems by its fossils to be nearly connected with that 

 formation. The Rev. T. Wiltshire, in his excellent paper on the Red Chalk of England, 

 suggests that " probably it is better to regard it as an intermediate formation between 

 the Lower Greensand and Lower Chalk which comes into being when the Gault and 

 Upper Greensand have almost thinned out." 



6. The Gault of Folkestone and Wissant, as above stated, forms the base of the 

 upper half of the Cretaceous System. 



The second or lower division, as it occurs in England, has been the subject of 

 considerable discussion and research by Messrs. Judd and Meyer. 



Mr. Judd objects entirely to the name " Lower Greensand " as applied by 

 English geologists to all the Cretaceous beds that occur under the Gault, and 

 advocates the dividing of this portion of the system into Upper Neocomian 

 ("Aptien," D'Orb.), Middle Neocomian {" Urgonien," D'Orb., " Barremien," Coquand), 

 and Lower Neocomian ; but it is not quite clear to me that we possess in England the 

 Lower Neocomian as found on the Continent. 



Mr. Judd states at p. 241 of the 'Quart. Journal Geol. Soc.,' vol. xxiv, 1868, 

 " The Speeton Clay contains at least seven divisions, well marked lithologically, still 

 better defined pala3ontologically. They are, 1st, the Upper Neocomian, having its 

 equivalent in the Lower Greensand of the South of England; 2nd, the Middle 

 Neocomian, of which the Tealby series of Lincolnshire is the equivalent ; 3rd, the Lower 

 Neocomian, now recognised for the first time in this country." The remaining five 

 divisions of the so-called Speeton Clay should be classed, according to the same author, in 

 the Portland and Kimmeridge, or upper portion of the Jurassic system. 



Mr. Meyer, in his notes on the correlation of the Cretaceous rocks of the south, 

 east, and west of England (' Geol. Mag.,' vol. iii, 1866), and Mr. Topley, in his paper 

 on "The Agricultural Geology of the Weald" (1872), follow the Geological Survey in 

 dividing the Lower Greensand (in ascending order) into Atherfield clay, Hytle beds, 

 Sandyate beds, and Folkestone beds. Mr. Meyer describes these beds as follows : 



'* 1. The lowest subdivision of the Greensand, the Atherfield Clay of Eitton, and Lower 

 Neocomian (in part) of foreign authors, is known to occur beneath the Kentish-rag series 

 of Folkestone, although unexposed in the coast section, and its continuity has been traced 

 inland past Maidstone, Sevenoaks, Redhill, and Guildford. It is visible on the shore 

 beneath Redcliffe, and still more conspicuously at Atherfield, ill the Isle of Wight, 

 westward of which it scarcely appears to have extended. The thickness and mineral 

 composition of this group is very uniform throughout its course, consisting in its 

 lowest layers of sandy clay, which, where the fossils are most abundant, has become 

 consolidated into hard, nodular concretions of shell-rock. A stiff brown or bluish clay (the 



