The Jurassic Rocks of Great Britain. 419 
The Upper Kimeridge consists of alternations of finely laminated, 
dark, bituminous and lighter shale, with hard brown bands, which 
have received special notice as forming the lower portion of the 
Speeton section. There is also a trace of the Upper Kimeridge at 
Settrington. All other exposures are in beds which must be referred 
to the Lower Kimeridge, which consists mainly of blue clays and 
shales with septaria. Some light has been thrown on the subject by 
boring at Irton: there are also feeble indications in the Vale of 
Pickering and the lowest slopes of the Tabular Hills. Undoubtedly 
the best section in the Lower Kimeridge was afforded by Sir C. 
Strickland’s brickyard at Hildenley, three miles west of Malton, 
which yielded a most characteristic basal Kimeridge fauna, and 
there have also been a few fossils picked up on the Wold slopes, 
which clearly belong to the Lower Kimeridge. On the whole, 
however, the fauna of the Yorkshire Kimeridge seems somewhat 
meagre, and when we find (p. 881) IEhynchonella inconstans 
quoted as a “ Portlandian”’ fossil, we can only express surprise that 
a form, which in the South of England is eminently characteristic 
of the very lowest Kimeridgian, should here be found on such a 
high horizon. 
In chapters devoted to “ Physical History” and “Scenery and 
Denudation” the author summarizes his experiences in accordance 
with his own views. Under the former heading he states his 
belief that the beds of the Yorkshire Lias were formed in a some- 
what land-locked area, having its shore-line towards the north-west, 
whilst lying open towards the east. The South Yorkshire deposits 
were formed beyond this district, and constitute the northern limits 
of a more extended area. Towards the close of the Liassic period the 
bed of the sea was elevated, or the water became shallower from 
the gradual accumulation of material. In the west the upper part 
of the lias has been subjected to considerable local denudation, 
whilst on the coast the Blea Wyke beds exhibit a considerable 
thickness of sandy shales with Serpule, Trigoniz, etc., showing 
shallow-water conditions and forming a gradual passage from the 
Lias below. The exceptional preservation of these beds constitutes 
one of the most obscure problems in the physical history of the 
Yorkshire Jurassics, and Mr. Strangways, in this chapter, rather 
favours an explanation which he has elsewhere opposed. 
The physical history of the Lower and Middle Oolites appears 
to afford evidence of a series of oscillations throughout the period, 
with sediment invading the area mainly from the west and north, 
in which direction the shore-line probably lay. The last discharge 
of mechanical sediment is recorded by the Middle Calcareous Grit, 
even after corals had begun to form in the area; but at last there 
came a cessation of mechanical impurities and a large extent of 
organic rock with corals concluded a phase in the history of the 
district. The peculiar marginal character of the Corallian lime- 
stones, forming an imperfect ring as they do round the clays of the 
Vale of Pickering, is attributed, and we think rightly, to the accidents 
of stratigraphy rather than to original deposition in that form. But 
