22 D. C. DAVIES ON THE UPPER CARBONIFEROUS 



the conglomerate immediately underlies the great mass of sandstones 

 of group 4, and that it is underlain in its turn by the sandstones and 

 breccias of group 2, I incline to the opinion of the older geologist, 

 and place it, with him and Prof. Sedgwick, in the middle group of 

 Permian strata. 



Section 13 is regarded by Mr. Hull* as a typical section. With 

 that of Alberbury, it has, in group 2, sandstones and marls, in 

 group 3 a somewhat similar conglomerate, with a base of trappoid 

 breccia, which perhaps belongs more properly to the top of group 2 ; 

 these are overlain by the usual mass of red and purple sandstones. 



The district lying between this point and the Bristol Channel has 

 been well described by Prof. Ramsay f, who places the Abberley 

 conglomerates on the same horizon as that of Alberbury. There is 

 a remarkable resemblance in the mineral composition of the breccias 

 described by him and 'those of group 2 in the Ifton section, com- 

 posed, as both are, of felstone, porphyry, greenstone porphyry, 

 amygdaloid slate rocks, altered sandstones, and quartz. 



It was from the occurrence of large scratched boulders in this 

 conglomerate that Prof. Ramsay inferred the prevalence of glacial 

 conditions in the climate of that period. 



Section 14 is from the pit-sinking of Coppice-Hall colliery, near 

 Walsall : I had hoped to be able to give the section of the new 

 sinking at Sandwell Park instead ; but all the attempts I have 

 made to obtain any information of it or of the promised book 

 descriptive of it have been ineffectual. Both the Walsall and 

 Tunstall sections are situated, though far apart, on the eastern side 

 of the New-Red- Sandstone plain of Shropshire and part of Stafford- 

 shire ; and they are interesting from the similarity of the strata in 

 group 2 to those of the Ifton section in the same division, pointing 

 (as this similarity does) to a continuity underground through the in- 

 tervening area. 



Section 15 is one described by Mr. Howell $ of the strata overly- 

 ing the Warwickshire coal-field. In group 1, Mr. Howell states 

 that the /S^Yorfo's-limestone occupies a position about 50 feet below 



limestones, we should naturally expect to find fragments of the coal also, which 

 we do not. There is also, as far as I am acquainted with them, an absence in 

 the limestone fragments of the characteristic fossils of the Spirorbis-limestone. 

 From what source or sources, then, were they derived ? I offer the following 

 suggestion towai'ds a solution of the question. By a reference to group 3 of 

 the vertical sections, it will be seen that a large quantity of calcareous matter 

 was deposited during the accumulation of the red marls, in the shape of concre- 

 tions and interstratified beds. If we imagine any considerable area of these, 

 which were older than the conglomerate itself, exposed to denuding agencies, it 

 is easy to conceive how in a rough shallow sea the denuded limestone boulders 

 would be rolled up along the shore-line and become cemented together by such 

 portions of the denuded red sands and marls as did not float back into still 

 water. May not the conglomerate therefore be made up of denuded Permian 

 limestones redeposited with, and cemented together by, Permian marls ? 



* Triassic and Permian Rocks of the Midland Counties, p. 13. 



t Quart. Journ. Geol. Soc. vol. xi. pp. 191-199. 



| The Geology of the Warwickshire Coal-field, p. 26. 



