﻿514 MR. J. T. STOBBS ON" THE MARINE BEDS [Allg. I905, 



It will be observed that, while these collieries lie all around the 

 Coalfield, they are noticeably absent from the very heart of the 

 district, the simple reason being that the more valuable coal-seams in 

 the area exist at depths so great that no shafts have as yet been 

 sunk to them. 



Another striking feature is the strong representation of collieries 

 in the vicinity of Longton ; this is largely due to the work of 

 Mr. John "Ward, and may be regarded as his ' mark ' on the map. 



Y. Description oe the Deposits. 



(a) Physical characters. — The marine bands, in every case, 

 occur in shales, of various colour — sometimes dark, sometimes pale- 

 grey. In the horizon below the Twist Coal at Nettlebank an impure 

 limestone (2 feet 9 inches thick) was met with. As previously 

 stated (p. 503), there is physically nothing to distinguish these marine 

 shales from any other Coal-Measure shales. To test this point, I 

 have repeatedly taken practical miners (who are exceedingly quick 

 to uotice slight differences in the rocks themselves) to examine 

 spoil-heaps where a large amount of debris, containing a marine 

 fauna, had been tipped. In every instance, they were unanimously 

 of opinion that no points of difference were to be observed, save in 

 the character of the contained fossils. The shales were more or 

 less fissile, and in some cases were what miners call ' grewn ' to the 

 coal, that is, devoid of parting-plane : there was a total absence of 

 anything of the nature of current-bedding, or any sensible break in 

 the deposition of the measures contiguous to the marine horizons. 

 Nodules and ' bullions ' were found in two of the beds described, 

 namely, the bed below the Twist Coal at JSTettlebank and the Seven- 

 Peet Banbury bed. Their abundance, however, varied considerably 

 from place to place ; and in the latter instance, on the west side of 

 the Coalfield, they constitute quite a feature of the deposit, while 

 on the east side they are comparatively rare. The bullions are 

 invariably fossiliferous, and are especially worthy of the notice of 

 collectors. 



(6) Occurrence of the fossils. — The fossils are usually in a 

 good state of preservation, and especially so in the bullions, where 

 they are generally uncompressed ; they were distributed throughout 

 the shales, and not confined to any one layer or bedding-plane. In 

 every band the individuals were numerous, and this in itself is a 

 valuable feature for practical geologists, while for mining-engineers 

 it is inestimable, since so much of their prospecting- work is done 

 by drilling; and, where the core varies from 1 to 3 inches in 

 diameter, if the fossils were at all rare, the bed would probably 

 escape notice altogether. In this connection, it may be observed 

 that the upper marine bed in the Cheadle Coalfield was first 

 discovered in a 3-inch core. 



Respecting the fossils, with the exception of Lingula mytiloides, 

 brachiopods are comparatively rare. The most abundant forms 



