408 Rev. W. D. Conybeare on M. de Beaumont's Theory 



rise towards the general elevation or' the subjacent transition 

 chains, which, however, appear often unconformable : indeed 

 Mr.Murchison has informed me that even the old red sandstone 

 near Castle Carregkennon is unconformable, being Hearty 

 vertical, while the incumbent carboniferous lime is not inclined 

 above 35°. 



The north edge of the coal-basin is affected by consider- 

 able faults ranging E. and W. : one throws up the carboni- 

 ferous limestone 4 or 5 miles within its general outcrop from 

 Penderyn to the arched strata of Bwa Main near PontNedd 

 Vechon at the head of Cwm Neath. Similar to this, but on a 

 smaller scale, is the fault at Cribborth lime rock in the upper 

 part of Cwn Tawe, where an interval of three quarters of a 

 mile takes place between the two outcrops of the limestone. 



The line of elevation of the Malvern Hills, also N. and S., 

 may, I apprehend, be certainly referred to this same aera, being 

 evidently anterior to the deposition of the new red sandstone 

 which skirts its base horizontally. Its main mass is a protrusion 

 of sienitic rocks, which apparently have been the agents in ef- 

 fecting this disturbance, which throws up at a high inclina- 

 tion the transition limestone covering its western slope. The 

 transition limestone of the Abberley Hills in the prolongation 

 of this line has apparently been elevated by the same con- 

 vulsion ; but I am at present unable to state in what manner 

 the coal-fields of Pensax and Billingsley, at the north end of 

 this line, are affected. 



The coal-field of Coalbrook Dale and the subjacent transi- 

 tion limestone of Wenlock Edge appear in like manner to have 

 been elevated by the protrusion of the trap rocks of the Wre- 

 kin chain, and at the same period, that is, anterior to the a?ra 

 of the new red sandstone : the line of direction is N.E.and S. W. 



The Flintshire coal-field and its subjacent carboniferous 

 lime repose conformably on the exterior chains of the North 

 Welsh transition slates, so that the same forces of eleva- 

 tion must have affected all the members of these exterior 

 chains ; but, as before, anteriorly to the a?ra of the new red 

 sandstone, the line of direction again differs from the Wrekin 

 chain, being N.W. and S.E. 



If we pass to the central coal-fields, we find that of Dudley 

 reposing on the transition limestone elevated by a high 

 anticlinal line ranging N. and S., with a slight tendency to 

 N.E. We naturally incline to refer this convulsion to the 

 eruptions which have left the overlying mass of trap on the 

 south. Dykes of the same rock have been found intersecting 

 the coal in Tividale. The elevated quartz rock at the foot ot 

 the Bromsgrove Lickey, which is in the continuation of this 



