100 Morris — Oolites of Northamjpton, ^c. 



out by Mr. Hull,) so that the Inferior Oolite, which attains a thick- 

 ness of 250 feet at Leckhampton, is reduced at Stonesfield, near 

 Oxford, to 15 feet. The Fullers Earth and Great Oolite are subject 

 to similar variations. The former, as well as the Bradford clay, 

 becoming thicker to the south, while the sands below the Inferior 

 Oolite also vary in thickness in the same area. 



Professor Phillips has alluded to a similar variation in the York- 

 shire area, " The great series of sandstones, shales, coal plants, and 

 ironstones lying above the Lias and below the Oolite of Gristhorpe, 

 500 feet thick in the Peak and the great range of cliffs at Stainton- 

 dale, is only 270 feet thick near Thirsk, and is further reduced near 

 Bransby, until on the banks of the Derwent it is scarcely traceable." 

 (op. cit p. 97). 



The whole thickness of the south-western formation, where fully 

 developed, is upwards of 600 feet. The marine conditions and cal- 

 careous character of the strata in this area is strongly contrasted with 

 that of Yorkshire, where the limestones are extremely thin, and are 

 intercalated with sandstones, clays, ironstones, and shales, contain- 

 ing an abundance of land-plants such as Cycads, Ferns, and Coni- 

 ferae, with beds of " Moorland Coal " accompanied with Unio 

 and Estheria : the whole series having a somewhat corresponding 

 thickness of 600 to 700 feet. Thus the difference of condition in 

 these two districts of deposition is well-marked by the abundance 

 of organic and chemically-formed deposits (limestones) in the one 

 area, and of inorganic or mechanically-formed deposits (shales and 

 sandstones) in the other. Besides which, in the latter area, the 

 geological sequence between the Lias and Cornbrash is not com- 

 plete, for the associated thin limestones contain fossils from which 

 it is inferred that the whole series should be classed with the Inferior 

 Oolite, the equivalents of the Great Oolite, Bradford Clay, and Forest 

 Marble being there wanting ; this view is taken by Dr. Lycett/ 

 and also by Dr Wright.^ Dr. Oppel, however, whilst he includes 

 the Lower Sandstone, Shale, and impure Limestone and underlying 

 Dogger with the Am. MurcMsoncB and Am. Hiimphriesianus zones 

 of the Inferior Oolite,^ appears to consider the Upper Sandstone 

 and Shale as belonging to the Bath Oolite formation.* On the other 

 hand, Dr. Oscar Fraas says, " In the north of England (Yorkshire), 

 the lowercoal or moorland sandstone consist of a great local sandstone 

 formation, with a large quantity of fragments of plants which is 

 placed between 'the Inferior Oolite and the " Grey" Limestone of 

 Phillips. But the Grey limestone of Yorkshire is merely what the 

 FuUer's-earth of the south, the Marnes a foulon and the Marnes 

 vesuliennes also are, the S of the Swabian " Brown Jura." ^ 



Professor Phillips, however, from the comparative sections given 

 in the paper before alluded to, seems to be of opinion that the Oolite 

 of Gristhorpe is the equivalent of the Bath Oolite, and that the over- 



» Pal. Soc. Suppl. to Gr. Ool. MoUusca, p. 115. The CotteswoM Hills, p. 74. 

 2 Quart. Journ. Geol. Soc. 1859. D'Orb. Prodrome, 1850. 

 s Die Jura-Formation, p. 326, 333. * Ibid, p. 439. 



5 Quart. Journ. Geol. Soc. vii. Translations, p. 60. 



