322 T/ios. H. Waller — Volcanic Rocks, Nuneaton. 



as in the Malverns, to a single seam which is very difficult of 

 detection. 



This zone is the highest band of the Cambrian visible in the 

 Nuneaton District, occurring immediately to the east of the uncon- 

 formably overlying Carboniferous. Fossils have been obtained from 

 it in the quarries to the south-west of Merivale Park, and in the 

 Stockingford railway cutting. 



No recognizable fossils have been met with in the Hartshill quartz- 

 ite, but those enumerated above from the various zones of the Stock- 

 ingford shales allow us to assign the Cambrian rocks of Nuneaton 

 to their approximate position in the general succession of Cambrian 

 deposits. These Stockingford shales fall apparently into the same 

 systematic position as the well-known Upper Cambrian shales of the 

 Malvern Hills — representing the grey and black shales which there 

 lie between the Hollybush Sandstone below and the Dictyonema bed 

 above. Lingula pygmea and Obolella Salteri occur in the lowest 

 shale zones of the Malvern Hills, Sphcerophthalmus alatus and Agnostus 

 pisiformis are among the characteristic fossils of the black shales 

 above. In other words, the Stockingford beds come into the place 

 of a part of the Lingula Flags of North Wales — possibly ranging to 

 the Upper Dolgelly. With the Scandinavian succession the agree- 

 ment is even closer ; the zones of Agnostus sociale, Beyrichia Angelini 

 and Sphcerophthalmus alatus (= zone of P. scarabeoides) occurring in 

 the same order in the Midlands, in Scania and in Norway. 



Although the underlying Caldecote Volcanic Group has distinctly 

 afforded the material of which the basement bed of the Hartshill 

 Quartzite is composed, it is doubtful if the systematic break between 

 the Caldecote and Hartshill formations is of great moment. The 

 Caldecote ashes have the same general strike and amount of inclina- 

 tion as the overlying quartzite, and are equally unmetamorphosed. 



Both the Stockingford Shales and the Hartshill Quartzite are 

 pierced by intrusive dykes of Pre-Carboniferous diorite. This rock 

 has been already described by Mr. Allport, F.G-.S., in a memoir which 

 has become classic in the history of British Petrography. 



A preliminary notice of the petrographical characters of the 

 Caldecote igneous rocks by Mr. Waller will be found in the paper 

 which follows the present communication. 



VII. — Preliminary Note on the Volcanic and Associated Eocks 



op the Neighbourhood of Nuneaton. 



By Thos. H. Waller, B.A., B.Sc. 



THE relations of the various rocks of the district lying to the 

 North and South of Nuneaton have already been discussed by 

 Prof. Lapworth from the data afforded by investigation in the field. 

 He put into my hands many specimens of the different rocks for the 

 purpose of microscopical examination. I have also received specimens 

 from Mr. W. J. Harrison, and have collected some myself. Mr. J. 

 J. H. Teall has also placed at my disposal a number of slides which 

 he has had prepared from material of his own collecting. 



