KIMMERIDGE CLAY. 125 



Speeton in Yorkshire is especially to be referred to the gault or blue 

 and gray marls of Cambridgeshire, Kent, and Sussex ; but that it also 

 contains some characteristic indications of the Kimmeridge clay, and 

 therefore we should expect that in Yorkshire these two strata are not 

 separated as in the South of England. This agrees exactly with all that 

 can be observed of their geological position ; for there is no evidence 

 that any other stratum divides them, but on the contrary, much probabi- 

 lity that they are in contact. Had ostrea delta been found at Speeton, 

 there could remain no doubt on the subject ; but as that fossil is known 

 to lie near the bottom of the Kimmeridge clay, its presence at Speeton 

 was not to be expected, because there the lower portion of the clay is 

 not exposed. Lastly, though no layers of green sand occur in a distinct 

 form in Yorkshire, chloritic sand accompanies most of the fossils at 

 Knapton, and many of those at Speeton. 



FOSSILS OF THE KIMMERIDGE CLAY. 



Wood, agreeing in structure with dicotyledonous plants . . . Elloughton. 



Ostrea deltoidea (Min. Conch, and Smith, Strat. ident.) ... Kirby-Moorside,near Helms- 

 ley, Elloughton dale, Wei- 

 ton, also Wilts, Berkshire, 

 and Dorset. 



Belemnites ... ... ... Brantinghanr 



Ammonites plicomphalus ? ... ... Kirby-Moorside. 



Fragments of ammonites ... ... From Settrington & North 



Grimston. 



THE fossils of the Kimmeridge clay in Yorkshire, owing to the rarity 

 of its exposure, are yet very imperfectly known. Ostrea deltoidea is 

 believed to be characteristic of the lower part. It occurs at Elloughton, 

 within a few feet of the red chalk ; proving the great unconformity of 

 strata beneath the Yorkshire wolds. (See Section No. 9.) 



