552 Aubrey Strahan — Bocks beneath the Coal-measures 



thickness of strata intervening between the coal-seams and the 

 Silurian platform, while in others the coal-seams appear to rest 

 almost directly upon this platform. The irn persistency of these 

 lower beds led Professor Lapworth to conclude that the Stockingford 

 shales were brought " in a long-curved strike fault against the Coal- 

 bearing beds of the Upper Carboniferous." 1 The same view was 

 taken by Mr. Harrison also, who writes that the line of fault between 

 the Coal-measures and the Stockingford Shales is " marked by a line 

 of brick-pits in which the rubbed- up material or 'fault-stuff' is 

 worked," and again, in reference to Dosthill, that " on the west of 

 the hill .... a line of fault runs, by which the Triassic strata are 

 placed on a level with the Cambrian shales, while on the eastern 

 side a parallel fault of less ' throw ' places the Coal-measures in a 

 similar position." 2 



The mapping of the boundary, however, about Oldbury, placed it 

 beyond doubt that in this neighbourhood it was not a fault, but an 

 unconformable superposition of the one series upon the other, while 

 the section at Chilvers Coton proves that the absence of the con- 

 glomeratic sandstone is due to attenuation and does not imply a fault. 

 Nor in the intermediate ground is there any reason to attribute the 

 varying distance of the seams from the top of the Silurian rocks to 

 a fault rather than to the known variability of the lower beds of the 

 Coal-measures, the material referred to by Mr. Harrison as ' fault- 

 stuff ' being merely such fireclays and shales as are commonly found 

 in connection with seams of coal in the Coal-measures. The relations 

 of the Coal-measures to the Silurian platform appear to be exactly 

 paralleled by those of the Coal-measures of South Staffordshire to the 

 platform of the Upper Silurian rocks, on which they rest in that 

 county. Professor Jukes writes 3 that "the Silurian rocks were 

 greatly denuded and worn away, and cliffs and hollows formed in 

 them, on, against, and over which the Coal-measures were deposited, 

 both lying in a nearly horizontal position " (p. 81) ; and again, " We 

 have already, in examining the base of the Coal-measures, seen the 

 way in which at particular spots the lower beds of that formation 

 filled up hollows in the Silurian rocks and obliterated their little 

 pre-existing cliffs, and thus formed a smooth floor for the deposition 

 of the chief mass of the Coal-measure beds " (p. 135). 



These words describe exactly the manner in which the earlier 

 beds of the Coal-measures appear to have been laid down in 

 Warwickshire. We have here a platform of rocks varying in 

 hardness, and forming in consequence such peculiarly undulating 

 ground as is found near Merevale. At the commencement of the 

 Carboniferous period they must have presented just such a surface 

 for the reception of the first deposited sediments, the igneous rocks 

 standing up, as now, in small hills above the general level of the 

 shales, and it seems to have resulted from this that a thick mass of 



1 Gbol. Mag. Dec. II. Vol. IX. p. 565. 



2 Midland Naturalist, vol. viii. p. 72, 1885. 



3 The South Staffordshire Coal-field (Memoirs of the Geological Survey), second 

 edition, 1859. 



