B. Jones — On the Carboniferous Deposits of Shropshire. 367 



Now if we turn back to the Cornbrook section, distinguished 

 as Section A, we shall find that the following relations subsist with 

 that of Harcott, or Section C, so far as the Lower and Sweet CoaP 

 deposits are concerned. We shall refer to the relationship of the 

 strata above those Coals later on : 



A 4 



= 



Cll. 



A 5 



= 



C 12. 



A 6 



■s 



C 13, 14, 15 



A 7 



= 



C16. 



A 8 



= 



C17. 



A 9 



^ 



018. 



A 10 



= 



C19. 



Considering that the sections are from points between six and 

 seven miles apart, it appears to me both pass through the same 

 geological horizon to the extent of the foregoing strata. 



How, then, does it happen that at Harcott we have no lower 

 Coal-measures and no Millstone Grit? The answer is, that previous 

 to the deposit of A 10, the Millstone Grit had been upheaved, pro- 

 bably at the same time as that of Brown Clee. It was then de- 

 nuded, not partially as at the Brown Clee, but from top to bottom, 

 leaving the Old Eed Sandstone exposed; upon this A 10 was de- 

 posited, and the others above it in order (vide Fig. 1). 



It appears to me that this upheaval was not confined to one or 

 two points, but that it extended away to the North for many miles, 

 for in the Coalbrook-dale field we see that the Little Flint Coal (the 

 equivalent of A 10), as I shall presently show, is no great distance 

 from the representation of the Grit, 



Harcott and CoalbrooTc-dale. — As a preparatory step, it becomes 

 necessary to revise the nomenclature of the Coal-seams in the 

 Southern part of the Coalbrook-dale district, and to make out a clear 

 CO- relation between them, and those in the Northern portion. 



We are led into endless confusion by new names being given to 

 old and well-defined beds, as well as to the divisions of some of the 

 thicker seams caused by " splitting up." Then an examination of 

 this kind prepares us for certain changes which we find developed 

 more and more as we proceed southward, changes which have been 

 maintained even as far south as Cornbrook, where they are so great 

 that we never could co-relate those deposits with Coalbrook-dale, 

 unless we fully established that they are in proportion to the distance 

 going south from the North of the Coalbrook-dale Field. 



The Penny-measure, though changing from 31 feet thick at Lodge- 

 wood, to 6 feet at Madeley, maintains its name all through the district. 

 The following names of Coals are constant over the whole Northern 

 district : — 



Sulphur Coal. 

 Upper Clunch Coal. 

 Clunch Coal. 

 Two-feet Coal. 



"Best Coal. 

 Handle Coal. 

 Clod Coal. 

 Little Flint Coal. 



In the Puddley Hill Pit we find the Clunch Coal for the first 

 time as we go South called Sill or Silk Coal. In the Madeley Pits 

 we find the Sulphur Coal divides, and the lower portion is called 



1 The expression Sweet Coal is commonly used to distinguish it from Sulphur 

 Coal, which prevails in the Forest of "Wyre Coal-field. 



