1014 DR R. KIDSTON, MR T. C. CANTRILL, AND MR B. E. L. DIXON. 



region, shows that these measures become progressively thinner from oust 

 to west, and thinks that this is best explained by assuming an unconformity. 

 But the base of the Sulphur Coal Group has not yet been either defined or 

 identified. When discussing the sections of the Billingsley Engine Pit and 

 the Billingsley Pit (p. 372) Dr Arber places it at the [Main] Sulphur Coal ; 

 but in the case of the Highley Pit (p. 373) he puts it 3 feet 4 inches below 

 that seam, and in the Kinlet Pit (p. 373) at 193 feet below. If the Sulphur 

 Coal Measures below the Sulphur Coal swell out (from north-east to south- 

 west, by the way) from 40 inches at Highley to 193 feet at Kinlet, what 

 difficulty is there in believing that a general thickening of all the measures 

 between the Main Sulphur Coal and the Sweet Coals may have taken place, 

 and that the varying distance between the two sets of coals is due to this 

 cause alone ? 



Before any argument in favour of unconformity can be founded on such 

 considerations, the base of the Sulphur Coal Group must first be defined and 

 identified. An excellent opportunity of doing this was afforded by the 

 sinking of the Kinlet Pits about 1893, when the fossil flora might have been 

 collected, the Spirorbis -limestone identified, and signs of unconformity 

 looked for. But nothing of the kind was attempted ; and little can now be 

 hoped for till the whole district is mapped in detail and fossil plants 

 collected from every available exposure. It will then perhaps be possible 

 to determine the special lithological characters and distinctive fossils of the 

 Sulphur Coal Group, to trace its base at the surface, and to ascertain its 

 relationship to the Sweet Coal Group. It may even be possible to locate 

 its base in some of the older shaft-records. 



7. This is in agreement with previously expressed opinion. 



8. Dr Arber, while recognising that the Sulphur Coal Group of Wyre Forest 



belongs to the Transition ( = Staffordian) Series, correlates it (op. cit., 

 p. 429), not with the Halesowen Sandstones, but with the Red Clay Group 

 [Etruria Marls], and remarks that, if the Halesowen Sandstones are present 

 in Wyre Forest, they must be thin. On the contrary, it seems to me that 

 to recognise in the Sulphur Coal Group the Halesowen Sandstones of South 

 Staffordshire is far easier than to recognise the Etruria Marls. Unfortu- 

 nately, the last-named subdivision of the Staffordian Series has nowhere 

 yielded sufficient plant-remains to enable its palseobotanical horizon to be 

 determined : in North Staffordshire it has been placed in the Staffordian, 

 because it overlies the Black Band Group, which, on account of its Transition 

 fauna, is placed in the Staffordian. 



If the Halesowen Sandstones are represented by the Sulphur Coal Group, 

 the Etruria Marls ought to be looked for in the uppermost of the barren 

 measures that intervene between the Sulphur Coal Group and the Sweet 



