THE GEOLOGIST. 
49 
On the Geology of tie Beaufort and Ehlw Vale District of the South 
Wales Coal-field. By Geokge Phillips Bevan, Esq., M.D., F.G.S. 
With the exception of the very able memoirs drawn out by Sir H. de la 
Beche, in the " Geological Survey," Vol. I, and the sections of the same 
survey, as compiled by Mr. David Williams, no coal-field has been so 
little described or worked out as that of the South Wales basin. 
Although the work of a master geologist, yet the very nature of these 
memoirs, describing the general arrangements of the rocks in the south- 
west of England, altogether precludes any attempt at minute geology, 
which, indeed, should mostly be supplied by local workers. Other 
coal-fields have been ably and intimately described, but this particular 
field only in very general terms. Why it should be so I know not, 
unless it is that only of late years its vast resources have been opened 
up, and that its many romantic vallies, teeming with beauty above and 
brimful of coal and mine beneath, have been made accessible either to 
the tourist or the mining adventurer. Every year, however, sees new 
railways opened in Monmouthshire and Glamorganshire ; and I have 
little doubt but that the completion of that magnificent work, the 
Crumlin viaduct, has done more than anything else to attract persons 
to that part of South Wales, either from a love of the beautiful, or the 
scientific interest attached to it. Eor the study of practical geology in 
its several aspects, this coal-field possesses many advantages, particu- 
larly in physical geology and the peculiar manner in which sections 
are obtained, owing to the nature of the ground. In the important 
branch of palaeontology, also, it is by no means deficient ; for, at least 
in this distiict, plants of the coal, as well as shells, fresh water and 
marine fish-remains have been discovered most abundantly. I propose, 
therefore, to give a brief sketch of this portion of the field, feeling 
assured that it is by local and minute investigation that the truths of 
the first great principles are upheld, and any new difficulties solved. 
The greatest length of the South Wales coal- basin is from east to west, 
extending from Pontypool to Kidwelly, a distance of about seventy 
miles, while the greatest breadth is about twenty-five miles from Merthyr 
or Hirv ain to Cardifi'. In this measurement I have excluded the Pem- 
