502 DISLOCATIONS — COAL AND LOWER NEW RED SIMILARLY AFFECTED. 



metal. Here it was evident the speculators were sinking upon a point of eruption. This trap of 

 Pool Hays, judging from the specimens which I collected at the mouth of the old trial shaft, was 

 in parts a hard, coarse-grained, grey, granular greenstone with much white felspar ; in other parts 

 an amygdaloid, containing nests of zeolite, coatings of crystallized iron pyrites, &c. 



Principal lines of elevation and subsidence. 



To give an accurate account of all the faults by which the tract around Dudley and 

 Wolverhampton has been affected, would almost complete a detailed history of the 

 coal-field, which is incompatible with the leading objects of this work. I shall, there- 

 fore, simply point out the chief lines of dislocation, their direction and connection 

 with the elevated masses of Silurian rocks, and with the points and lines of trappean 

 eruption. It is, indeed, impossible to describe all the dislocations around the margin 

 of the field, for as yet we have little information to be relied upon. Enough, however, 

 is known to prove, that the surrounding and overlying Red Sandstone has been sub- 

 jected to the same movements as the coal measures, a fact which, being clearly seen in 

 open work at Sedgeley, is proved in other natural sections round the field, and has 

 recently been substantiated by the sinkings of the Earl of Dartmouth. This con- 

 formability of the Lower New Red Sandstone to the coal measures, a fact with which 

 the older geologists were unacquainted, is of considerable theoretical and practical 

 importance. The same phenomenon having been pointed out in the Shropshire coal- 

 fields, pp. 95 et seq., it is probably very general in the central counties, while in the 

 north of England it has been observed by Professor Sedgwick to be of partial occurrence 

 only. In Staffordshire, as in Shropshire, indeed, the mere superficial features of the 

 rocks often warrant such an inference. At the quarries in Sandwell Park, for example, 

 the strata are highly inclined and much broken, dipping to the north-west, and indi- 

 cating lines of fracture, which trending from the neighbourhood of the Bar Beacon on 

 the north-east, to the end of the Rowley Hills on the south-west, are precisely parallel to 

 those faults near West Bromwich, by which the coal measures have been thrown up 

 from beneath the red sandstone. (See Map.) That these fractures have been caused 

 by the rise, or efforts to rise, of various rocks of volcanic origin, no person acquainted 

 with the subterranean structure of this field can doubt. Lord Dartmouth's works have, 

 indeed, proved the fact as respects the eastern flank of the field 1 . 



The manner in which the coal is cut off at the edge of the field near Wolverhampton 

 is also specially worthy of notice. The bed there called the "thick coal," together 

 with the heathen coal, and the underlying ironstone measures (the gubbings and blue 



1 Mr. Dawson, whose endeavours have been before alluded to, being anxious to discover the coal measures 

 extending eastwards beneath the great mass of red sandstone, caused horizontal drifts to be made in that 

 direction ; and in following the coal till it thinned out, a boss or two of hard, unstratified, granular felspar rock 

 was cut through, as represented in PI. 37. f. 1. 



