35 

 ADDRESS ON THE SOUTH WALES COAL FIELD. 



Bv G. PHILLIPS BE VAN, Esq., F.G.S., &c. 



Gentlemen of the "Woolliope and Cardiff Natural History Societies, — 

 From the point upon which we stand, viz., the Llanhilleth-hill, we should, if the 

 day was somewhat clearer than it is, have a view of a very considerable portion 

 of the South "Wales coal field ; and I have selected this point because it embraces 

 not only the coal basin itself, but a distant view of the hills that bound it. Such 

 a view is especially interesting to you as geologists, not merely from its scenic 

 beauty, but from tlie associations that it calls to the memory of past geological 

 etas. To the North we have the Old Red eminences of the Brecon Beacons, a 

 little to the East of which is the isolated limestone summit of Pen Carreg 

 Calch. Far to the East we see the Red Sandstone of Monmouthshire, beyond 

 which are the collieries of the Forest of Dean ; and to the North of which the 

 Silurian district of Usk just conies within the view, the prolongation (though 

 interrupted) of that district of Woolhope from which we take our name. To 

 the South, on the other side of the Bristol Channel, are the limestone ranges of 

 the Mendip Hills, fadiug away into the Old Red of the Quantock Hills of North 

 Devon. Now what do these distant views suggest ? Do they not call to mind 

 the days before denudation had canied away its thousands of feet of intervening 

 strata, and when the South Wales field was united with the Somerset, the 

 Forest of Dean, the Shropshire, the Staffordshire, the Lancashire, and the 

 Irish coalfields? Even if stratigraphical geology did not prove these facts, and 

 even if were not possible to constnict horizontal sections to prove the continuity 

 of these basins, we have the lithological and palaeontological evidence to help us, 

 as for instance in Lancashire, w^here the bottom coal beds which are nearest what 

 is there called the Canister rock, are characterised by the same peculiarity of 

 fossil shell that we have in South Wales. If for no other reason, therefore, the 

 view that we now see is a grandly suggestive one, and one can scarcely help 

 re-constructing in one's mind the original condition of those carboniferous shores 

 which we now see so broken up and isolated. 



The external shape of the South Wales coal field may be considered as 

 pear-shaped, the broad end of the pear being at the eastern or Pontypool end 

 (close to where we are standing), from whence a gradual diminution of breadth 

 takes place westward as far as Carmarthenshire, which we may consider the 

 stalk of the pear. In its long axis this distance is from 60 to 70 mUes, while 

 the greatest breadth of the field is from Hirwain to Cardiff, a distance of some 

 24 miles. The whole of the circumference, or nearly the whole, is surrounded 

 by a tolerably uniform belt of Mountain Limestone, which on all sides towards 

 the coal field is overlaid by an equally uniform bed of Millstone Grit ; but 

 away from it overlooks the Red Sandstone valleys in remarkably fine escarp- 



B 2 



