

•2< 



92 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jlllie 17, 



ft. in. 



Grey shale 10 



Shale and small pale ironstone pins, with one thin layer 



of shelly sandstone 12 



Cement - stone — pale - coloured limestone in cuboidal 



blocks. (Glyphia) 3 



Dark shale, with ironstone balls. (Pecten) 12 



Iron-rock or compacted balls 3 



Shale, yellowish-grey and dark 20 



Sandstone (Pearson's quarry) 12 



Shales 20 



Cement-stone nodules 1 



Pale clay 1 



/ Sandstone, brown, yellow, &c 40 



\ The lower part sometimes very ferruginous 3 



Shale and ironstone balls 3 



Ferruginous and shelly oolite, resting on upper lias 7 



The total thickness of the Lower Oolitic Series is thus found to be 

 489 ft. in this combination. 



If we now compare these sections measured on the actual coast 

 and against the ancient sea-cliffs, we find in regard to the Middle 

 Oolite formation only differences of thickness ; the Oxford Clay- 

 being remarkably thinner near Thirsk, but the Kelloway rock thicker. 

 But in all the strata below the Cornbrash the differences between 

 the two sections are very great. 



The Cornbrash, as seen on the Yorkshire coast, is never above 

 5 feet thick. It contains several distinguishable parts — a thin part 

 at the top rather laminated, and a part at the bottom, argillaceous, 

 or actual clay ; while in the middle is one thick mass, or two beds, 

 of shelly and somewhat ferruginous limestone, hardly oolitic. It 

 contains Nucleolites orbicularis, Myacites securiformis, Ammonites 

 Herveyi, and many other shells, but hardly a trace of Belemnites. 

 Near Thirsk, and for a great breadth of the moorlands eastward of 

 Hambleton, I have not clearly seen it. It is, however, conspicuous 

 in Newton Dale, and thicker than on the coast. 



The series of sandstones and shales between the Cornbrash or 

 Kelloway rocks and the calcareous beds which first succeed below, 

 yields on the coast two bands of ironstone, and contains Cycadacece ; 

 and one band (rich brown iron-ore) appears near Thirsk. 



The calcareous shelly beds below, which occur on the coast, and 

 seem to lie in the place of the Forest Marble group of the south of 

 England, appear under Hambleton at the base of the carbonaceous 

 sandstone, and may perhaps be regarded as including the shelly 

 nests in the lower part of the sandstone. A bed of Ostrea Marshii 

 occurs in both situations, near the middle part of the shelly series ; 

 a bed of Ostrea crassa lies towards the lower part at Hambleton ; 

 but Belemnites and Terebratulce have not been seen there, as at 

 Gristhorp and Cloughton. 



Below this point there is great difficulty in tracing lines of con- 

 temporaneity across the district from the coast to the inland cliff. 

 If we suppose, in conformity with many observations, the Gristhorp 

 plant-bearing series to be merely a local deposit, not seen at any 



