1016 DR R. K1DSTON, MR T. C. CANTRILL, AND MR E. E. L. DIXON. 



Taking 3 and 4 together, where is the difficulty in supposing that the 

 Sulphur Coal Group of Highley, which extends southward to the northern 

 edge of the Dowles Valley at Kingswood, was once connected and continuous 

 with the same group of Rock and Mamble, 2 miles to the south-west? The 

 erosion produced by the Dowles Brook itself is surely a sufficient cause of 

 the present want of connection. 



Again, it is not clear why a separate basin of deposition is required for 

 Claverley because of its supposed lithological peculiarities, when Dr Arber 

 lays such stress on the impersistence of lithological types (op. cit., pp. 433-4). 



It appears to me that the gradual subsidence of a landlocked basin will 

 adequately explain the phenomena. Near the land, so much coarse sediment 

 was laid down in places that beds of conglomerate and coarse "espley" 

 grits predominate, while elsewhere, or farther away, the usual types of 

 Coal Measure deposits — carbonaceous clays, shales, and coal-seams — were 

 spread out. Where the basin was shallowest, the sequence would be least 

 complete. Some parts of the floor rose so far above others that they were 

 not covered by any Coal Measure deposits till the Transition period, as in 

 the Mamble region and at Chelmarsh, where, in each case, the Sulphur 

 Coal Group, having overlapped or overstepped the Middle Measures, rests 

 directly on the Old Red Sandstone floor. The Claverley boring seems to 

 have entered one of these uprisings, for only 950 feet of Coal Measures were 

 found to intervene between the base of the Keele Beds and the floor of 

 Silurian rocks. Conversely, where the basin was deep the measures are 

 much thicker, as in the Dowles Valley, where, in the so-called Alton boring, 

 which commenced probably several hundred feet lower in the sequence than 

 the Sulphur Coal Group of the Highley region, 1102 feet of Middle Measures 

 alone were proved (op. cit., p. 376). At Shatterford there are probably at 

 least 2000 feet of measures between the base of the Keele Beds and the 

 Old Red Sandstone floor. 



With such variations in the depth of the basin of deposition, it is clear 

 that overlap would result, and the necessity of assuming more than one 

 basin is not very obvious. The lithological type of sediment would 

 necessarily vary with the character and proximity of the coast. The coal- 

 seams would be liable to thicken and thin, to disappear, and to deteriorate 

 m quality ; and a normal series of carbonaceous shales, clods, and coal-seams 

 such as we have in the Highley region might well pass horizontally in the 

 direction of the shore into a series of red marls, green grits, and useless 

 smuts like those of Shatterford and Claverley. 



We have now to consider the bearing of the fossil plants collected from the 

 Wyre Forest Coal Field by Messrs John Rhodes, John Pringle, and Robert Eckford, 



