SPEETON CLAY. 9 



and sjMiies of a Cidaris occur, wliicli appear to be distinct from the Cidaris spines, ninety-four 

 feet above, in the pink band. There are, moreover, no traces of IMastcr suhyhhosm nor 

 Discoidea cylindrica in this bright-red bed ; and Ammonites cannot be seen, though so 

 numerous in the Speeton Clay, upon whicli it rests. This red band gradually becomes 

 nodular, and of a bluish cast, and gradually merges into the Speeton Clay. 



" Inland the Yorkshire beds put on a somewhat difierent appearance, for on the escarp- 

 ment of the Wolds, as at Great Givendale, the beds of Red Chalk abound in pebbles 

 and in Terehratitla bipUcafce, a feature that is absent at Speeton, though conspicuous at 

 Hunstanton, in Norfolk. 



"A careful inspection of the fossils derived from the Red Chalk series of Yorkshire and 

 Norfolk shows that the two extremities of the bed are very distinct in character, and have not 

 much in common, and that the southern stratum is a moi'e littoral deposit than the northern." 



l\Iy friend John Leckenby, Esq., E.G.S., of Scarborough, having studied critically the 

 fossils of the Speeton Clay, has kindly supplied the following note on that formation, from 

 which it appears that until now the true relations of this deposit have not been clearly 

 understood. 



" The Speeton Clay of Yorkshire, besides many minor subdivisions, presents two 

 important and well-marked sections ; well-marked lithologically, still more so by their 

 fossils. The line of separation midway, or nearly so in the series, is also distinct and clear, 

 with no passage-beds indicating a transition from one set of conditions to another. Its 

 entire thickness cannot be less than 400 feet, but in consequence of the denudation of the 

 inclined edges of its beds it nowhere presents a continuous section of more than 150 feet. 



" The lower division is characterized in its upper beds by Ammonites and Gas- 

 teropods, which I at one time felt inclined to refer to the O.xfordian system, and many 

 palaeontologists yet contend that the thick coronated Ammonites v/hich here abound 

 belong to the Oxfordian group. Without, however, doing violence to our preconceptions 

 of stratigraphical relations, we shall find that they approach much more nearly to 

 Portlandian types, as figured by d'Orbigny; &\\(\Aiii. (Jraye-w/z^^s cannot be distinguished 

 from a common, but unpublished form, in the Speeton Clay. In the lowest beds of 

 this lower division are found Am. inpUcatus, Am. cxcavatus (var. aUernatus, Von Buch), 

 with univalve and bivalve shells identical with species which I have obtained from the 

 Kimmeridge Clay of Lincolnshire, in a railway-cutting near Brigg. The line of demarcation 

 before referred to is characterized by a thickish band of pseudo-coprolites, and by many 

 remains of Saurian animals ; it would appear that here there has been a period of repose, 

 during which the Saurian dwellers upon a shallow reef disported themselves, and that we 

 have a well-marked division between the close of the Jurassic and the commencement of 

 the Cretaceous period. A large and almost perfect example was lately procured and is now 

 in the possession of Right Hon. Lord Londesborough, the lord of the manor of Speeton. 



" The habit of referring the whole of the Speeton Clay of Yorkshire to the Cretaceous 

 period, in deference to established authorities, has hitherto prevented a clear reading of 



2 



