592 ME. E. D. VEENOiJy" 0:S THE GEOLOGY AND [DeC. I912, 



Geological Survey maps, this boundary is an arbitrary one, which 

 coincides neither with any physiographic feature nor with any 

 break in the stratigraphical succession of the beds. We may thus 

 infer that the evidence for the Permian age of these rocks is 

 exceedingly vague and inconclusive. From a study of these rocks 

 in the field, I propose to show that the first important break in the 

 stratigraphical succession occurs at the Corley Conglomerates (see 

 p. 603), and that the underlying 1000 feet of rocks of so-called 

 ' Permian ' age are conformable to the Coal Measures, with which 

 they must therefore be grouped. In confirmation of this view. I 

 have been able to obtain fossil plants of Upper Coal-Measure age 

 from these supposed Permian rocks. 



The pre-Carboniferous Floor of the Coalfield. 



The Coal Measures rest upon an irregular floor of Cambrian rocks, 

 which is only known where it is exposed at the surface, or where it 

 has been proved in deep borings. This floor, together with the 

 overlying Coal Measures, has been elevated along three parallel 

 lines which trend in a north-west to south-east direction. Portions 

 of two of these old ridges are the anticlines of jS'uneaton and 

 Dosthili ; but there is a third ridge in the neighbourhood of Market 

 Bosworth, which is completely hidden beneath the Trias. The 

 occurrence of a faulted anticline of Upper Coal Measures at Arley 

 may indicate yet another fold in the pre-Carboniferous floor. 



(A) The Coal Measures. 



Basement conglomerate. — Resting unconformably on the 

 Cambrian (Stockingford Shales) is the basement bed of the Coal 

 Measures — a soft, coarse, false-bedded, ferruginous sandstone with 

 quartz-pebbles. This rock, which was first noticed by Dr. Strahan 

 (S6), is of value in mapping the boundary between the Cambrian 

 and Carboniferous formations uear Mere vale, where it makes a 

 conspicuous feature, and at Dosthili. This conglomerate, as well 

 as the succeeding strata of shales and fireclays, may be absent, 

 so that the lowest seam of coal comes to rest directly upon the 

 Cambrian. 



Where the conglomerate is absent, or where there is no section, 

 the junction is clearly indicated by the rising ground, at the points 

 at which the Cambrian comes to the surface. The base of the Coal 

 Measures has also been proved some distance away from the outcrop 

 in certain of the colliery sinkings near Bedworth. 



The grouping of the measures. — Between the basement 

 conglomerate of the Coal Measures and the Corley Conglomerate at 

 the base of the Permian, there is a vertical thickness of more than 

 2500 feet of Coal Measures. It is possible, on both lithological and 

 palaeontological evidence, to effect a twofold grouping of these 

 rocks. 



The loAver subdivision, about 700 feet in thickness, includes all 



