1826.] which appear on the Yorkshire Coast. 345 



and below them. It is, therefore, a priori, improbable that they 

 should reappear on the Yorkshire coast. 3. In the section visi- 

 ble in the clifF near Speeton (and also at Knapton, as appears by 

 the " Geological Survey of the Yorkshire Coast," p. 58), the 

 chalk marl rests immediately on the Pickering clay without any 

 trace of the Shanklin-sand, or of the green-sand. It is, there- 

 fore, probable, that the intervening gait has also disappeared.* 

 I, therefore, conclude, on a review of the best evidence with 

 which I am acquainted, that the whole of the Pickering clay on 

 the coast is to be identified with the Kimmeridge clay; and 

 that all the formations, from No. 2 to No. 8 inclusive, are want- 

 ing in the Yorkshire section. 



Sect. 5. — Oolitic JJmestom,&)C. of the Vale of Pickering. 



The high broken tract of country, extending from the Vale of 

 Pickering through the north-eastern moorlands of Yorkshire to 

 the extremity of Huntcliff, has already been considered as one 

 physical region. It will, however, be convenient to divide the 

 strata which successively present themselves in this region into 

 three distinct groups or formations. 1. A formation of oolitic 

 limestone and calcareous grit. 2. A coal formation. 3. A great 

 argillaceous deposit (alum-shale or lias), immediately inferior to 

 the two preceding, which occupies a considerable portion of the 

 cliff between the Peak of Robin Hood's Bay and the village of 

 Saltburn, and forms the base of the hills which overlook the 

 plain of Cleveland. A short account of these groups will form 

 the subject of the three following sections. 



The calcareous grit, constituting the lower portion of the first 

 group, is finely exposed in the promontory of Filey Bridge, and 

 a little further to the west is surmounted by beds of oolitic lime- 

 stone. The whole group is thence prolonged about thirty miles, 

 in a direction nearly due west, to the escarpment which over- 

 hangs the plains of Thirsk. The formation afterwards ranges in 

 a south-easterly direction to Malton, where it crosses to the left 

 bank of the Derwent, and for some way runs nearly parallel to 

 the chalk downs. Farther to the south it disappears for many 

 miles under the chalk ; but it allervvards reappears (according to 

 the geological map of Mr. Smith) at Newbald, and is thence 

 prolonged, in a direction parallel to the general bearing of the 

 other strata, to the north bank of the Humber. 



♦ From the geological map of Mr. Greenough, as well as from Mr. Smith's geologi. 

 cal map of Yorkshire, we might suppose that soii)e of the sand beds belonging to the 

 group immediately inferior to the chalk, extended without interruption at the base of 

 Yorkshire wolds. How far the delineation is hypothetical, I am not prepared to say; 

 but I saw no trace of the group in question, and it seems to have been unknown to the 

 autiiors of the "Survey of the Yorkshire Coast." In the geological map of Yorkshire, 

 the clay of the vale of Pickering is called the Oaktree-clay, a term which conveys no 

 definite information ; for in Mr. Smith's system, the A\'eald clay and the Kimmeridge 

 clay are unfortunately confounded under the common name of Oaktrccclay. 



