172 Mr. J. Lycett on the so-called Sands 



zone. A constant mineral feature is the presence of small 

 oval grains of hydrate of iron disseminated through the rock ; 

 a structure which, however, is not peculiar, as it is present in 

 the Inferior Oolite at Dundry and in the Lias of France. 

 From 2 to 4 feet is the thickness of this bed in the Cottes- 

 wolds. 



Immediately overlying this upper Ammonitiferous bed are 

 several others of hard brown or yellowish calcareo -siliceous 

 sandstones, in which fossils are usually very sparingly distributed, 

 and, from the evidence these afford, the beds have by universal 

 consent been assigned to the Inferior Oolite. 



In Yorkshire, the lofty iron-bound coast at the Peak and at 

 Blue Wick exhibits the same remarkable deposit in considerable 

 thickness, and slightly modified in its mineral character from 

 the Cotteswold Sands. In a visit which I recently made to this 

 coast, in company with my friend Professor Morris, the identity 

 of the lower portion of the Dogger or Inferior Oolite of Phillips 

 with the Gloucestershire Sands was strongly impressed upon my 

 mind. At Blue Wick the Dogger is altogether about 80 feet in 

 thickness, and rises in successive beds in descending order from 

 the rocky beach into the face of the lofty cliff, the lower 40 feet 

 representing the sands of the Cotteswolds. Beneath these suc- 

 ceed the hard beds of the Upper Lias Shale, 200 feet thick, 

 followed by the Middle Lias, nearly equal in mass ; ultimately, 

 at the Peak, facing Robin Hood's Bay, these great deposits are 

 all exposed in one vast unbroken section, forming a lofty mural 

 cliff, nearly 400 feet in height and three miles in length, in the 

 course of which the Dogger attains the summit of the cliff. 

 Words are scarcely adequate to express my admiration of this 

 grand exposition of the lower Jurassic rocks, which for extent 

 and completeness can scarcely be paralleled. Proceeding north- 

 wards, the upper 40 feet of the Dogger loses more than half its 

 thickness, and the lower portion, or representative of the Sands, 

 thins out altogether; a great fault then succeeds, by which the 

 Middle Lias is upraised to the summit of the cliff. 



The highest bed of the Upper Lias consists of black, finely 

 laminated shale, the transition to the sandstone above being 

 abrupt and very distinctly marked. The sands are here com- 

 pacted into thick-bedded, dark grey micaceous sandstones in 

 the lower part, and into brownish or foxy-coloured micaceous 

 sandstones in the upper part, so that the whole nearly resembles 

 the Cotteswold Sands, and differs chiefly in its greater compact- 

 ness. Fossils are distributed very sparingly throughout the 

 mass of the sandstones, but they are present more abundantly, 

 as in the Cotteswolds, in two calcarco-argillaccous zones, situated 

 in like manner, the one at the top, the other near to the base of 



