A HISTORY OF WARWICKSHIRE 



The Lower or Purley Shales are exposed in Purley Park Lane and 

 in the cutting on the Midland Railway near Nuneaton. The beds are 

 generally reddish-purple and contain manganese ores which were worked 

 by pits at various points along the outcrop. Fossils have been obtained 

 from the Purley Park Lane sections, and include among others minute 

 forms of the brachiopods Lingu/a, Obolella sagittalis, and Acrothele granu- 

 lata ; the sponge Protospongia fenestrata, and the trilobite Conocoryphe 

 exulans. 



The Middle or Oldbury Shales are best seen in the Midland Rail- 

 way cutting at Stockingford, and in quarries and cuttings at Chapel End. 

 The beds are characterized by black carbonaceous bands. They have 

 yielded remains of the trilobites Agnostus pisiformis var. soda/is, Olenus 

 nuneatonensis, Sphczrophthalmus a/atus, and Ctenopyge pecten ; together with 

 Beyricbia angelini. 



The Upper or Merevale Shales are exposed in an old quarry 200 

 yards west of Merevale Abbey. They consist of greenish-grey shales 

 and have yielded numerous examples of the hydrozoan Dictyonema 

 socials. 



A small inlier of the Stockingford Shales was detected at Dosthill, 

 south of Tamworth, by Mr. W. J. Harrison ' in 1882. The rocks are 

 pierced by a mass of diorite. Sections in the shales have been recorded* 

 as occurring in the side of the high road a quarter of a mile south of 

 Dosthill, and in a small pit near Stockall Barn. The beds dip south- 

 west at 20 to 40, and consist of highly-altered grey and olive-coloured 

 sandstones. 



The following table shows the probable relationships of the Nun- 

 eaton Cambrian beds to those of other districts : 



Nuneaton. Wales, etc. 



Merevale Shales Upper Dolgelly (Dictyonema-beds) ) TT T . 



Oldbury/ upper Lower Dolgelly ..... . / U PP er L" 1 ^ FIa g 



Shales I lower) 



II 



ga 



j| ~ [ 

 g 



,. 

 Purley t upper/ Ffestmlo g and Maentwrog beds . Lower Lingula Flags 



Shales! lower ........... Menevian 



(Paradoxides--zone) 



Camp Hill Quartzite and Limestone . . 0/enel/us-zone 



Tuttle Hill Quartzite 

 (Park Hill Quartzite 



The Cambrian rocks of Nuneaton afford evidence of having been 

 deposited in a shallow sea whose floor was gradually undergoing subsi- 

 dence. The quartzites and sandstones were perhaps to some extent shore 

 deposits laid down at no great distance from a tract of land. This must 

 have consisted in part of the Archzan volcanic ashes, for we have seen 

 that much ground-down volcanic material was incorporated in the lower 

 beds of the Hartshill Quartzite. As the sea bottom sank, the land, 

 wherever this was situated, was gradually submerged, and the coarse 



' Lapworth, Gtol. Mag. (,882) p. 563 ; Harrison, Mid. Nat. vol. viii. (.885) and vol. i*. (.886). 



' Strahan, Geol. Mag. (1886), p. 551. 

 8 



