PRE-CARBONIFEROUS FLOOR OF THE MIDLANDS. 
71 
% 
difficult question, and its consideration will be better deferred 
till the mode of occurrence of the same rock in other localities 
has been described. 
The Stockingford Shales .—Resting upon the quartzite, and 
forming a region of rugged ground which lies to the west of 
the Hartshill range, we find a considerable thickness—nearly 
2,000 feet—of rubbly shales or mud-stones, which may be called 
the Stockingford Shales, because they are well exposed in the 
railway cutting of the Midland line between Stockingford and 
Nuneaton. At the base—where they rest upon the quartzite— 
these Cambrian shales vary from red to purple in colour, but 
higher up they are more commonly grey or black. Nodules 
of manganese—formerly worked in several little pits—occur 
in the red shales. The general dip of these beds is to the 
south-west, at angles of from thirty to as much as seventy 
degrees. Lying parallel to the quartzite, the shales occupy a 
much larger area, extending from beyond Atherstone in the 
north to Marston Jabet in the south, a distance of more than 
ten miles; while they occupy a surface-strip whose breadth 
varies from half a mile to rather more than a mile. At each 
extremity of this strip the beds roll over and assume an 
easterly dip, which is well seen in the old quarry near the 
Hall at Marston Jabet; and which is also indicated by the 
corresponding anticlinal of the coni measures north of Ather¬ 
stone. Thus the structure of the country is that of an 
anticlinal, broken through by a great fault about the centre 
(near Hartshill), but preserving its crest to the north and 
south of this point of maximum dislocation. The shales are 
traversed by several dykes or intrusive sheets of diorite (well 
described by Mr. S. Allport *) which run more or less parallel 
to the strike of the shales. Here and there the dioritic rock 
thickens out into a boss, such as the great mass which is 
quarried near Oldbury Hall. Further south a fine section 
showing four dykes, traversing and sending out tongues into 
the shales, can be seen in the railway cutting at Cliilvers 
Coton. 
Owing to the difference in hardness between the diorites 
and the shales, steep ravines have been eroded in the latter ; 
these form a striking feature in the scenery round Hartshill. 
In the Stockingford cutting red shales are seen at the 
Nuneaton end, and these are overlaid by purple, grey, and 
black shales which undulate considerably, but whose average dip 
is at a high angle to the west. The only fossil I obtained here 
was an Obolella. At Camp Hill the red basement shales are 
* 
Quarterly Journal Geological Society, Yol. XXXV., p. G37. 
