Geology of Coalhrook Dale. 473 



be, in some places, at no great depth from the surface. But lines of disloca- 

 tion are traced with difficulty through that formation, the different strata of 

 which are rarely characterised by fossil remains, or by any great dissimilarity 

 of lithological structure. 



Underlying the new red sandstone, these coal-measures would probably have 

 remained yet for ages unknown, had not portions of them been broken offand 

 uplifted, and this too in an order beautifully commensurate to the wants of man. 

 A few seams of coal and ironstone cropping out to day, originally led to the 

 discovery of a valuable deposit ; and though the means of working them were 

 Ihen limited, yet was the supply easily attainable. In time, as the demand in- 

 creased, so did the means multiply, and thus were successively brought into 

 use, the gradual descending downcasts of the coal-measures, from the outcrop 

 at the Steeraways, then over the Ketley fault to the Lightmoor fault, which 

 delayed further progress for some time, but was at last passed ; and now when 

 that stage of the coal is exhausted, there appears every prospect, though at still 

 greater depths, of a further supply, and probably equal to any with which we 

 are yet acquainted*. 



The third and last point claiming consideration, is the nature of the agents 

 which have modified the surface of the country. It having been shown in 

 p. 452 et seq., that the disturbances which affected this district not only de- 

 stroyed the continuity of the sedimentary deposits, but placed their fractured 

 portions on widely different levels, — it follows, that if the surface had not been 

 denuded, it would now present great irregularities, and even mountainous 

 ridges, exceeding, in some instances, 2500 feet in height. The existing surface 

 is, however, comparatively flat ; and it is therefore evident, that, in the ele- 

 vated central, western and southern districts, where only the lower divisions of 

 the coal-measures remain — all the upper strata, amounting to not less than 800 

 feet, with at least the whole of the lower new red sandstone, which was pro- 

 bably more than 1200 feet thick, have been removed; and that in the valley of 

 the Severn, as well as in that between Barrow and Shirlot Hills, not only have 

 the new red sandstone and coal-measures been completely denuded, but also 

 500 feet of Wenlock rocks in the former instance, and 600 feet of old red 

 sandstone in the latter. 



Notwithstanding, however, the extent of these effects, still the diversity of 



* The reader must not however infer, that coal and ironstone strata necessarily exist everywhere 

 beneath the new red sandstone of the surrounding districts, because it has been shown, that 

 although the coal formation, as a whole, may be extensively persistent, still from its littoral cha- 

 racter all the terms of the series are liable to rapid variations. The coal and ironstone will be 

 limited to an area, proportionate to the strength of the fluviatile currents. 



