A HISTORY OF WARWICKSHIRE 



neighbourhood of Nuneaton. They consist of a lower sandy division, 

 the Hartshill Quartzite, and an upper shaly division known as the 

 Stockingford Shales. 



In 1829 they were classed by Yates ' as of Silurian age, on account 

 of the resemblance of the quartzite to that of the Lickey Hills near 

 Bromsgrove. Subsequently however they were put into the Carboni- 

 ferous system; 1 the Stockingford Shales, which seemed to be perfectly 

 conformable with the overlying Coal Measures, were thought to be an 

 unproductive group of that formation, while the Hartshill Quartzite 

 was held to be a metamorphosed representative of the Millstone Grit. 

 No fossils had then been obtained from either of the two divisions, 

 and some of the shales have a decided coal-measure aspect. It is 

 evident however that Jukes 3 recognized their Silurian or even pre- 

 Silurian age. 



But the discovery in 1882 by Professor Lapworth * of a number of 

 fossils in the Stockingford Shales characteristic of the Lingula Flags of 

 the Upper Cambrian (then classed as Lower Silurian by the Geological 

 Survey) finally settled the age of the higher of the two sub-divisions ; 

 and in confirmation of these discoveries the revised issue of the Survey 

 map in 1886 represented the Shales and with them the Quartzite as 

 Lower Silurian. 



It still remained desirable to determine on independent evidence 

 the age of the Quartzite. This has since been rendered clear by the 

 recent discovery in its higher beds of a fauna highly suggestive of the 

 O/ene//us-zone of the Lower Cambrian of other regions ; and as Professor 

 Lapworth points out, ' it now appears exceedingly probable that the 

 whole of the Cambrian system is represented here in an attenuated 

 form.' 6 



The Cambrian outcrop of Nuneaton extends from near Bedworth 

 on the south-east to Merevale on the north-west, a distance of about 

 eight miles, the greatest width being about a mile. The beds dip 

 generally in a south-west direction at angles varying from 20 to 45, 

 having been tilted up by crumpling of the earth-crust at some time 

 subsequent to their deposition. The upper beds pass unconformably 

 under the Coal Measures of the adjacent coalfield, while the lowest beds 

 rest unconformably on the Archaean rocks already described. 



From base to summit the beds are pierced by dykes and sills of 

 intrusive diorite (camptonite), and the whole outcrop on account of the 

 relative durability of the rocks forms a low ridge of picturesque and 

 wooded country. 



The rocks are divisible in the following manner, in descending 

 order: 



1 Tram. Geol. Soc. ser. t, ii. 237. 



* Geol Survey map, 63 S.W. (1855); also Howell, The Warwickshire Coalfield,' Mem. Geol. 

 Surrey (1859), p. 8. 



'The South Staffordshire Coalfield,' Mem. Geol. Survey, ed. 2 (1850), p. 134.. 



* Geol. Mag. (1882), p. 563. 



8 Pnc. Geol. Atioc. xv. (1898), 338. 



6 



