1008 DR R. KIDSTON, MR T. C. CANTR1LL, AND MR E. E. L. DIXON. . 



would be found to deteriorate in quality and thickness, to become unworkable, and 

 finally to die out altogether. This remains to be proved. But that the pre- 

 Carboniferous floor did actually rise rapidly to the south and south-west is shown by 

 the fact that in the Mamble region the Sulphur Coal Group rests directly on the 

 Old Red Sandstone, there being no evidence that the Sweet Coal Group was ever 

 deposited (text-fig. 3). 



Certain other results followed from investigations in the type district of the 

 " Salopian Permian " at Upper Alley, .Highley, and Alveley. The discovery of a band 

 of Spirorbis-limestone and a thin coal-seam between 200 and 300 feet above the 

 base of these* red rocks led me to advocate their inclusion in the Upper Coal Measures.* 

 The almost complete absence of plant-remains was not a serious obstacle to this 

 proposal, as the fossil flora collected from the same group of rocks in South Stafford- 

 shire during the sinking of the Hamstead shafts had already led Dr Kidston to 

 determine the same beds at Hamstead to be of Upper Coal Measure age. This view 

 of the systematic affinities of the Lower Permian rocks of Salopian type has since 

 been adopted by the officers of the Geological Survey, who found that the same beds 

 in North Staffordshire are characterised by bands of Spirorbis-limestone, thin coals, 

 and Carboniferous plant-remains ; and under the name of Keele Series they are now 

 included in the Upper Coal Measures. 



Since that date, now twenty years ago, few additions to our knowledge have been 

 made. In 1901, while the aqueduct of the Birmingham Corporation Waterworks 

 (Elan supply) was under construction across the Wyre Forest Coal Field, I was deputed 

 to note the sections exposed along the pipe-trench. The result t showed that the 

 Coal Measures, where crossed by the pipe-track, " appear to consist of two groups : 

 a lower, of variegated marls with yellow and green sandstone . . . and a higher group 

 of grey and yellow sandstones with thin pyritous coals and one or more bands of 

 Spirorbis-limestone. The lower group has some likeness to the Old Hill Marls of 

 South Staffordshire and the Etruria Marls of North Staffordshire ; while the higher, 

 as seen at Win woods and Kingswood, and again at Woodhouse Farm near Button 

 Oak, may represent the Halesowen Sandstones of the former district and the New- 

 castle-under-Lyme beds of the latter." It followed from this that the lower group, 

 which rests directly on the Old Red Sandstone, if not the equivalent of the Etruria 

 Marls, must be Middle Coal Measures that have assumed the barren condition and 

 lithological peculiarities of the Etruria Marls. The plant-remains from the Cooper's 

 Mill exposure in the Dowles Valley had, however, already shown that there at least 

 the surface-beds are of Middle Coal Measure age. I felt, therefore, that of the two 

 alternatives the second was the more probable, though I did not feel justified in 

 putting this opinion into print, as to do so without further confirmation would have 

 run counter to the experience of my colleagues in North Staffordshire, who had found 



* Quart. Joum. Geol. Soc, vol. li (1895), p. 528 ; Colliery Guardian, vol. lxxiii, 1897, p. 581. 

 t Summary of Progress of the Geol. Survey for 1901, p. 63 (1902). 



