320 JURASSIC. 



feet in thickness, and it contains many plant-remains, ironstone- 

 nodules, thin seams of coal, and sometimes impure jet. 



It includes the main seams of Moorland coal, developed on 

 Grimston JNIoor, which vary from a few inches to eighteen inches 

 in thickness. Mr. Hudleston observes that the thickest seam is 

 of little economic value, but it is remarkable for its persistency 

 over a large area, extending from the coast inland as far as 

 Castleton and Coxwold. The coal rests on the soils which sup- 

 ported the plants from which it was formed. (See Fig. 47.) 



At Gristhorpe the plant-bed has yielded many cycads, including 

 the cycadean fruit Bcania, and ferns such as Sphenopteris, Pecopteris, 

 Ncuroptcris, etc., also Equisetitcs columnaris, Zamia, Otozainites, etc. 

 Plant-remains have also been found at Cloughton Wyke.^ Casts of 

 Pteroperna and Oslrea have been noticed, also Esthcria cojicentrica. 



Hard and siliceous sandstone near the top of the series is quarried for road-stone 

 at Harwood-dale. Soft jet was formerly worked at Gate Holm Wood, and High 

 Normanby, in the Hawsker district. 



Scarborough Limestone. 



This formation comprises a series of blue and grey shaly lime- 

 stones ('Grey limestone' of Phillips), with occasional ironstones, 

 shales and mudstones, 3 to 100 feet in thickness. The beds are not 

 oolitic, although they have been termed the ' Oolite of Gristhorpe.' 



The fossils include Belcmnites elongatus, B. giga7itais, Ammonites 

 Humphritsmnus, A. Blagdcni, Avicida Braamhuriensis, Gervillia aaita, 

 Perna rugosa, Pecien lens. Pinna cuneata, Trigonia costata, T. signata, 

 Gresslya peregrina, etc. INIany species have been obtained at 

 Hundale. 



According to INIr. Hudleston the beds are feebly developed at 

 Gristhorpe Bay (8 feet), but make a better show at White Nab and 

 in Scarborough Bay. They are best developed at Cloughton Wyke 

 (Hundale). These beds represent part of the Inferior Oolite ; 

 Phillips originally placed them with the Great Oolite.^ They are 

 not recognized in the southern part of Yorkshire, where the entire 

 series above the Cave Oolite consists of sands and clays. (See 



Fig- 47-) 



Sioneeliff Wood Scries. — This series, named by Mr. Hudleston, 

 consists of sands containing towards the base and upper part 

 intercalated beds and lenticular masses (pot-lids) of arenaceous and 

 siliceous limestone ; it is altogether about thirty feet in thickness.^ 

 The beds form a sort of escarpment on the steep bank of Stonecliff 

 Wood, facing the Derwcnt Valley. Some of the stone-beds are 

 used for building-purposes. The fossil remains link the beds with 

 the Scarborough Limestone. 



1 C. J. F. Bunbury, Q. J- vii. 179; J. Leckenby, Q. J. xx. 76; W. H. 

 Hudleston, P. Geol. Assoc, iii. 310. 



2 Q. J. xiv. 85. 



3 P. Geol. Assoc, iii. 329, 292 ; se6 also Strangways, Explan. Sheet 93 N.E. 

 (Geol. Survey), p. 17. 



