GEOLOGY 



Jukes, the unconformity was distinct, although the discordance was not 

 very striking. 



Of especial importance in the region is the Fire-clay, mined at 

 King's Swinford and Old Swinford, near Stourbridge, for the manufacture 

 of fire-bricks, saggers, crucibles, etc. Fire-clay is one of the kinds of 

 impure clay in the Coal Measures, and is usually regarded as an ancient 

 exhausted soil. The clay, in consequence, will bear intense heat without 

 melting, because of the small amount of lime, protoxide of iron and 

 alkalies contained in it.^ 



Many plant-remains have been obtained in the South Staffordshire 

 coalfield from the shaly beds, notably giant club-mosses {Lepidodendron 

 and Sigillaria), horse-tails {Calamites), and sundry ferns. Freshwater or 

 estuarine mollusca such as Anthracosia also occur ; and there are marine 

 fossils, such as Aviculopecten, Lingula, etc., as well as fishes, such as 

 Megalichthys, which have been found in some of the ironstone bands 

 belonging to the Lower Coal Measures. 



PERMIAN 



Throughout the greater part of the country there is a marked break 

 between the Coal Measures and the succeeding deposits of Red rocks, 

 the lowest portion of which is grouped as Permian. This unconformity 

 is conspicuous along the eastern side of the exposed coal-fields of Derby- 

 shire, Yorkshire and Durham. In the Dudley district we find that the 

 so-called Permian rocks are nowhere distinctly unconformable to the 

 Coal Measures, and at one time they generally overspread the area. 



The Permian is divided into : — 



Feet. 

 Upper Sandstones and marls (local) ..... 300 



Breccia, sandstones and marls, with beds of calcareous \ 



conglomerate | 200 to 500 



Lower Sandstones and marls 500 to 850 



The mass of the Lower Sandstones and marls and some higher beds 

 have in recent years been proved to contain not only occasional layers of 

 limestone with Spirorbis, but also thin coal-seams. They evidently con- 

 stitute a portion of the Upper Coal Measures. Mr. T. C. Cantrill 

 indeed is inclined to regard the whole series up to the Upper Sandstones 

 and marls, a series which may be 1,500 feet thick, as belonging to the 

 Upper Coal Measures.^ 



The breccia of the Clent Hills, which is reckoned to be about 450 

 feet thick, forms a bold range of hills rising to a height of 1,028 feet. 

 The breccia is overlaid by the Bunter pebble-beds and the range extends 

 by Romsley to Bromsgrove Lickey, which is about 900 feet high. At 

 Northfield the strata are well exposed. 



* See Analysis in Percy's Metallurgy, vol. i. p. 98. 



2 Quart. Journ. Geol. Soc, vol. li. pp. 530-533, and Coll. Guard., vol. Ixxiii. (1897) p. 

 581 ; see also W. W. King, Quart. Journ. Geol. Soc., vol. Iv. p. 97. 



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