The Thick Coal of South Staffordshire. 



413 



day-light round a dome- shaped mass of Silurian (Wenlock) 

 limestone. 



To understand the nature of this out-crop, it must be stated 

 that the South Staffordshire coal-measures repose immediately 

 upon the Silurian beds, no Old Red Sandstone or Mountain Lime- 

 stone intervening, from which it is inferred that the area under 

 notice was dry land during the deposition of the absent members 

 of the geological series'. When the coal was in course of forma- 

 tion it would seem the underlying Silurian rocks had, to some 

 extent, assumed their present position; but, towards the close 

 of the Carboniferous era, the igneous action, which had in this 

 locality been a disturbing element from the commencement, 

 became more intense, and in one place especially it found a 

 ready vent through which the mass of molten material, forming 

 the Rowley ridge of hills, was ejected. It is probable that, at 

 this period, the three existing dome-shaped bosses of Silurian 

 rocks, extending northwards in the line of the Rowley Hills, 

 were elevated very considerably above their former level, 

 throwing out the coal-measures which at that time more or less 

 completely covered them. Thus it is that we now find the thick 

 coal and other seams almost horizontal at a short distance from 

 the Silurian eminences ; but all round the flanks of these hills 

 the coal is highly inclined, and at its out-crop is only overlaid 

 by about ten feet of superficial deposits, consisting of drift- 

 sand and clay, containing water-worn fossils from the adjacent 

 Limestone beds. 



The thick coal, in its line of out-crop, has been nearly all 

 extracted; and as the quality of the fuel is not so good as 

 at greater depths below the surface, where it has not been 

 " weathered," faint hopes were entertained that geologists 

 would again be able to feast their eyes on an open-air section 

 of this, the most stupendous seam of coal which the country 

 possesses. Owing to the circumstance before mentioned, how- 

 ever, the thick coal open workings have been cleared, and 

 large quantities of what coal remained have been dug out. 

 The position of this seam is towards the top of the series of 

 principal deposits occurring in this coal-field. The workable 

 coal-measures in the typical part of the district consist of : — 



1. 



2. 

 3. 

 4. 

 5. 

 6. 



Brooch coal, about 

 Thick coal 

 Heathen coal 

 New Mine coal 

 Fire-clay coal 

 Bottom coal 



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The total thickness of the deposits below the thick coal is about 

 350 feet, containing upwards of 30 feet of valuable coal, while 



