338 



GEOLOGY OF THE BRISTOL COAL-FIELD. 



Lower Coal Measures have an average thickness of 2000 feet ; they 

 lie an enormous depth from the surface, and can only be reached 

 where they crop up. This will be at once evident by an examination 

 of the diagrams. This remark is especially referable to the lowest 

 seams. The principal collieries working this division of the Coal 

 measures, are at Yate, Pucklechurch, Wapley, Cromhall, the north 

 side of Kingswood, Fishponds, St. George's, Bedminster, Ashton, 

 l^ailsea, Holcombe, Yobster, and Ashwick. 



At Bedminster the seam may be conveniently divided into two 

 groups, the Bedminster and Ashton, the latter underlying the 

 former. 



Fig. 19. — Bedminster Coal-field, 



Ashton 



6 7 8 



a J 1 2 34 



a Carboniferous Limestone— J Millstone Grit — c Magnesian Conglomerate — 



d Keuper 



1. Little Vein. 5. Toad Vein. 



2. Great Vein. 6. Bedminster Little Vein. 



3. Top Vein. 7. Bedminster Great Vein. 



4. Smith's Vein. 8. Bedminster Top Vein. 



At Kingswood the lower Coal measures would not be workable 

 if they had not been brought near the surface by a considerable 

 upthrow, forming an anticlinal running in a S.W. direction 

 from the "West of Wick to the South of Fishponds, Till 

 lately we supposed that all the possible seams had been reached, and 

 that the Millstone Grit, or farewell rock appeared at Kingswood 

 and of course prevented any possibility of going lower. However 

 Mr. Cossham has proved that the supposed Millstone Grit is 

 Pennant Sandstone that lies above instead of below the lower seams. 

 The result is, that there remains a veiy extensive amount of Coal 

 yet to be reached. 



