﻿516 MR. J. T. STOBBS ON THE MARINE BEDS [Aug. 1905, 



The almost immediate succession, in order of deposition, of a 

 coal-seam by a marine shale is a circumstance that may throw light 

 on the conditions under which these seams were laid down. So far 

 as attention has been directed to the nature of the coals overlain in 

 this fashion, they do not differ in appearance or quality from the 

 other coals of the district. The following seams are associated in 

 this way with marine bands, namely : — 



The Bay Coal. 



The Priorsfield-Iroustone Coal. 



The coal below the Gin Mine at Florence Colliery. 



The Moss Cannel. 



The Seven-Feet Banbury Eider Coal. 



The coal below the Four-Feet at Draycott. 



The Crabtree Coal. 



VI. Scheme of Subdivision" op the Coal- Measures in North 

 Staffordshire by means of Marine Bands. 



Numerous attempts have been made in many of our coalfields to 

 correlate the coal-seams in different localities ; but, because palgeon- 

 tological evidence has been almost totally ignored in these efforts, 

 to that extent the results may be regarded as guesses, more or less 

 unsatisfactory. Such correlations lack anything of the nature of 

 rigid proof. In North Staffordshire, the tracing of these marine 

 horizons has placed the correlation on a different footing. This is 

 attested by the fact that, in certain operations of mining, such as 

 boring, sinking, and proving faults, these marine horizons have been 

 of actual service when otherwise there would have been doubt. 



In all Coal-Measure stratigraphy, however, it is advisable that 

 the knowledge of marine bands should be supplemented by that of 

 such other strata as satisfy the requirements of index-beds. In the 

 district in question, several bands of thin limestone crowded with 

 entomostraca have been traced ; and the subdivision of the Coal- 

 Measures, based on these palseontological 'lines' (which are not more 

 than 450 feet apart in the series) simplifies the work of identifica- 

 tion of certain seams. 



In the following synopsis are enumerated, in descending order, 

 the seams of coal and ironstone occurring between the index-beds 

 mentioned above : — 



ISpir orbis- Li mest ne . 



Bassey-Mine Ironstone and Coal. 

 Little-Bow or Gutter Coal. 



Peacock Coal. Eich plant-bed. 



Spencroft Coal. 

 Gubbin Ironstone. 

 Great-Eow Coal. 

 c ~„^rr, t r^^cm^,™ I Lower limit of the ranee of 



jSpZ-RO-EBJ-S-LIMESTONE i , ,, -ni-ji- ■ 



(_ Anthracomya Phulvpsi. 

 Cannel-Eow Coal. 



Wood-Mine Ironstone Eich fish-bed. 



Pennystone or Blackstone Ironstone. 



Deep-Mine Ironstone .., Eich fish-bed. 



