A. J. Jukes-Broicne — On the term Neocomian. 



311 



There are thus shown to be 215 feet of beds of various kinds 

 above the Eed Marl, but it is difficult in the absence of unconformity 

 to say where the Trias ends. Probably the 10 ft. of "greenish 

 sandy clay " belongs to the Trias. Similar beds occur in the same 

 position in the same locality. The geological age of the " white 

 sand" and the "black sand" is "not proven," but probably they are 

 Cretaceous, though there is no visible unconformity to show it. 

 The " variegated marly clay " is certainly Cretaceous, as proved by 

 the fossils quoted above. 



Eed Marl. 5. Yellow Sand. 



Greenish Sandy Clay. 6. Grey Sand. 



Black Sand. 7. Cherty Greensand. 



Dark grey marl and black clay. 8. Clay, with chert. 



* The place where the fossils were found. 



V. — On the Application op the term Neocomian. 

 By A. J. Jukes-Browne, B.A., F.G.S. 



MUCH confusion and difference of opinion appears to exist with 

 regard to the classification and nomenclature of the strata 

 which form the lower part of the Cretaceous system, and the chief 

 element of this uncertainty and confusion is the misconception which 

 prevails respecting the proper signification and application of the 

 term Neocomian. The object of the present paper is to explain the 

 continental usage of this name, and by showing its inapplicability 

 to any of our English strata, to prepare the way for a more satis- 

 factory grouping of our Cretaceous rocks. 



For many years English geologists were content with the nomen- 

 clature employed by the earlier students of the Cretaceous system — 

 Webster, Murchison, Mantell and Fitton. In 1864, however, the 

 French term Neocomian was introduced by Prof. Judd, 1 who adopted 

 it for the Cretaceous portion of the Speeton Clay, and Sir Charles 

 Lyell subsequently used it as a synonym for the whole Lower Cre- 

 taceous series in England as distinct from the Upper Cretaceous 

 series or the beds lying above the Lower Greensand. Consequently 

 in many text-books we find the following arrangement of the Cre- 

 taceous groups : — 



1 Quart. Journ. Geol. Soc. vol. xxiv. p. 218. 



