413 



to be identical with that of the Abberley Hills, also mentioned in pre- 

 vious memoirs. 



5. Principal lines of dislocation. — The whole of this carboniferous tract 

 has been upcast through a cover of new red sandstone, the lower mem- 

 bers of which are frequently found to have been dislocated conform- 

 ably with the inferior carbonaceous masses, proving (as formerly ex- 

 pressed by Mr. Murchison) that some of the greatest of these move- 

 ments took \i\ace subsequently to the deposits of the red sandstone. In 

 describing the faults along the boundary of the new red sandstone, he 

 directs particular attention to that of Wolverhampton, where the coal 

 measures dip slightly inwards from the line of fissure, along which they 

 are conterminous with the overlying strata, a fact perhaps without 

 parallel in this or the adjacent coal-fields (including Coalbrook Dale), 

 the usual phenomena being that, hovvever disrupted, the carbonaceous 

 or upcast strata always incline outwards, as if they would pass even- 

 tually beneath the lower new red sandstone on their flanks. This 

 exception is supposed to have been caused by the upheaving of a 

 subjacent mass of Silurian or trap rocks close to the edge of the line 

 of fault. 



Having next described the effect of the great longitudinal faults 

 produced by the upcast of the Wenlock limestone of Walsall, he shows 

 that the subterranean mass at Dudley Port (p. 410), is upon the same 

 parallel, i. e. from N.E. to S.W., if not directly on the same line of fis- 

 sure. This line of eruption is strongly marked on both edges of the 

 northern half of the coal-field extending to Cannock Chase. 



Another great axis of elevation which affects the Dudley field, di- 

 verges at a considerable angle from the former. It is prominently 

 marked by the line of the Rowley Hills, and after concealment for a 

 certain distance beneath the red sandstone to the S. of Hales Owen, 

 reappears in the ridge of the Lickey quartz rock. The lofty trappean 

 ridge of the Clent Hills is parallel to this last-mentioned axis. It 

 is further pointed out as remarkable that at the angle formed by the 

 confluence of these divergent lines of elevation, the Silurian or fun- 

 damental rocks of the tract are raised in inflated ellipsoidal forms from 

 common centres, the strata having a quaquaversal dip, in one case 

 completing the outlines of a very perfect valley of elevation. The 

 author infers that such curvatures are exactly what might be ex- 

 pected at the point of greatest flexure in the axis of the coal-field, 

 where the volcanic matter, unable to find issue, has produced these 

 inflated masses. There are numberless faults in this coal-field to 

 which no reference is made, it being stated that much additional labour 

 is required to give a complete history of them ; but attention is called 

 to the Birch Hill, Lanesfield, and Barrow Hill faults, which are the 

 principal transverse faults, and which the author conceives may be ex- 

 plained upon the principles of the theory of Mr. Hopkins, or as cross 

 fractures which have resulted from elevation of the coaj- field en masse. 



The memoir concludes with referring to the importance of one of 

 the problems to which the author has been directing public attention 

 during the last few years, viz. the probable extension of carboniferous 

 tracts of the central counties beneath the surrounding new red sand- 

 stone j and he rejoices that the deductions which necessarily follow 



