﻿Vol. 6 1.] BLEA WYKE BEDS IN NOKTH-EAST YORKSHIKE. 443 



[Blea Wyke Section (continued).'] 



Thickness in feet. 



M m f Grey sandstone, weathering into nodules 4 



fc> p J Brown ferruginous band, with a layer of belemnites at its base. 1 

 «! pq j Grey, false-bedded, very micaceous sandstone, with a band of 

 cq [_ Serpula and casts of belemnites at the base 5| 



^ . f Grey sandstone and sandy shale, with fossils in nests, Lingula, 

 |{jN etc 25 



^ ^ I Grey shale, with Lingula Beanii, etc. 7 



Below this comes a thick mass of shale with ironstone-nodules, 

 the Striatulus-Shales. Their thickness is doubtful: Tate & Blake 

 say 70 feet, but this is possibly an exaggeration. Farther west this 

 can be seen to rest on Alum-Shale, with Ammonites communis and 

 Leda ovum. 



The classification of these beds adopted in the foregoing section is 

 a slight modification of that proposed by Mr. Fox Strang ways in 

 the Survey Memoir. 1 The most important difference is that the 

 base of the Dogger proper has been drawn just below the Nerincea- 

 Bed, instead of some 25 feet lower down, as usual. The reason for 

 this will be discussed later. 



The base of the Blea Wyke Series is never clearly seen ; but it is 

 quite evident that between the undoubted Upper Lias with Ammo- 

 nites communis and Leda ovum (the Alum- Shale) and the sandy 

 Lingula-Be&s there occurs a considerable thickness of shale, litho- 

 logically very similar to the Alum-Shale, but containing fossils 

 which belong to a higher horizon; Tate & Blake ' 2 give the follow- 

 ing list of fossils (as quoted by Mr. Eox Strangways) : — 



Discina rejlexa. 

 Rhynchonellajitrensis (?) . 

 Waldheimia Lycetti. 



A vicula incequivalvis. 

 Avicula substriata. 

 Lima toarcensis. 

 Ostrea subauricularis. 

 Pecten disciformis. 

 JPecten pumilus. 

 Cardium substriatulum. 

 Gresslya abducta. 

 Gresslya donaciformis. 

 Leda cequilatera. 

 Trigonia literata. 

 Venus tenuis. 



Bentalium elongatum. 

 Actceon Sedgvici var. pulliis. 

 Cerithium armatum. 



Ammonites comensis. 

 Ammonites conipactilis. 

 Ammonites hircinus. 

 Ammonites insignis 0). 

 Ammonites jurensis. 

 Ammonites lectus. 

 Ammonites rudis (?). 

 Ammonites striatulus. 

 Amnion ites variabilis. 

 Belemnites athleticus. 

 Belemnites Icevis. 



The ammonites show that we have here a representative of the 

 jurensis-zone, while the other forms indicate a mixture of Liassic 

 and Oolitic organisms, the former being most abundant. Owing to 

 the poorness of the exposures, I have not attempted to verify the 



1 C. Fox Strangways & G. Barrow, ' The Geology of the Country between 

 Whitby & Scarborough' (Expl. Quarter Sheet 95 N.W.) Mem. Geol. Surv. 

 1882, p. 26. 



2 'The Yorkshire Lias' 1876, pp. 190-91; & 0. Fox Strangways, 'The 

 Jurassic Kocks of Britain : vol. i — Yorkshire ' Mem. Geol. Surv. 1892, p. 136. 



