CHAP. XI 
WA R WICKSHIRE 
171 
■WARWICKSIIIEE 
Some fifty miles to the north-east of the Malvern Hills, in the heart of 
the rich Midlands, and among the coal-fields and the New Ked Sandstone to 
which these Midlands owe so much of their manufacturing industry and 
their agi'icultural fertility, another little tract of Cambrian rocks rises to 
the surface 011 the east side of the Warwickshire coal-field between 
Nuneaton and Atherstone. So unobtrusively do these ancient strata take 
their place among their younger peers, that their venerable anticpiity wms 
for a long time undetected.^ They were actually regarded as parts of the 
Carboniferous series, which at first sight they seem to underlie conformably. 
It was not until 1882 that the mistake was corrected by Professor 
Lapworth, who proved the rocks to be Cambrian by finding undoubted 
Upper Cambrian fossils in them.- Subseciuent investigation enabled him 
to work out the detailed secpience of these strata. He found that the 
supposed “Millstone Grit” is a thick-bedded cpiartzite perhaps 1000 feet 
in thickness, and resembling the well-known quartzites of the Lickey and 
Caer Caradoc. The “ Coal-shales ” proved to be a series (possibly 2000 feet 
thick) of purple, green, grey and black shales, which from their fossils 
could be paralleled with the dark shales of the Upper Cambrian series of 
the Malvern Hills.® These shales are immediately overlain by the Coal- 
For our present inquiry, however, the chief feature of interest 111 these 
discoveries is the recognition of a group of volcanic rocks underneath ^ the 
quartzite. This group was named the “ Caldecote Volcanic Kocks by 
Professor Lapworth, who first recognized its nature and relations. Its 
rocks have been studied by Mr. T. H. MAller* and Mr. P. Paitley,-' and have 
been traced upon a revised edition of the Geological Survey map by kH. 
A. Strahan.'’ They consist of a thin series of well - stratified tubs 
apparently derived from andesitic lavas. Their base is not seen owing to 
the fault which brings down the New Pmd Sandstone against them. They 
are surmounted by the quartzite, which at its base is conglomeratic an 
contains blocks of the tuff. A mass of quartz-felsite is possibly intrusive 
in these strata, and is associated with a diabase-porphyrite. In these 
rocks, but still more in the shales which overlie them, numerous sills of 
diorite and diabase occur. The total thickness of rocks from the lowest 
1 Their antiquity was recognized by Yates as far bach as 1825 {Trans. i'oc 2nd series 
vol. ii. p. 261). They had been confounded with “ Millstone Grit and Coal-shale y 
Conybeare and Phillips, and this mistake was adopted on the maps and memoirs of the Geological 
Survey. 
^ Owl. Mag. (1882), p. 563. ® <■"(«• (1886), p. 319. 
^ Op. cit. p. 323. * ^P' !'• 
« Oeol. Mag. (1886), p. 540. In this paper full references will be found to the previous papers 
on the geology of the district. Jukes had recognized that the rock,s below the coal-beaiing 
strata were “older than the Upper Silurian, perhaps older than any Siluiian, . sr/i. 
Survey, “South Staffordshire Coal-field ” (1859), p. 134. 
