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ON A COAL-SEAM IN THE BERNICIAN SERIES 



OF NORTHUMBERLAND, AND ITS BEARING 



ON THE THEORY OF THE FORMATION 



OF COAL. 



G. W. BULMAN, M.A., B.Sc, 



Corbridge-on ■ Tyne. 



The Bernician series of Northumberland corresponds with the 

 Mountain Limestone of Derbyshire and the Carboniferous Lime- 

 stone series of Scotland. In it several coal-seams of minor im- 

 portance occur. Some of these are worked in the south-west and 

 north of the county. Among the best known is the Little Lime- 

 stone Coal, so called from its position in relation to that limestone. 



The coal-seam in question occurs lower down in the series, and 

 is one of the two known as Beadnell coals, from the name of the 

 place near which they are met with. The coast section where the 

 seam outcrops is a most interesting one, and has been carefully and 

 minutely described by Prof Lebour in the 'Transactions of the 

 North of England Mining Institute.' It is the position of this 

 seam with regard to the other rocks, and the bearing of this on the 

 theory of the formation of coal, to which I now wish to call attention. 



It has — like many of the coals in the Bernician series — its under- 

 clay, and is directly overlain by a limestone. On the theory of the 

 terrestrial growth of coal, and subsidence of the land, the gradually 

 sinking area on which the bed of vegetable matter had accumulated 

 would necessarily pass through a shallow-water stage, when sand 

 and mud would be deposited on the coal, before it reached the 

 stage of deeper and clearer water required for the limestone. 



A section not far from the one which contains the coal-seam shows 

 the typical transition. A bed of sand, coarse in the lower part and 

 becoming finer upwards, is succeeded by a thin clayey band with 

 carbonaceous matter — an old mud, partly of vegetable origin — and 

 then a limestone. 



The presumable interpretation of this is as follows : a coarse 

 sand-bed is accumulated near shore and in shallow water ; the area 

 sinks, and finer sand is deposited ; it sinks still more, and fine mud 

 only reaches it ; finally it becomes deep and clear enough for lime- 

 stone. The coal-seam and fire-clay occupy the same relative position 

 as this clayey band with carbonaceous matter ; they both overlie a 

 sandstone, and are overlain by a limestone. 



Nov. 1890. w 



