TRANSACTIONS OF THE SECTIONS. 47 
The next Section, numbered 2, crosses Llangeinor Mountain; here the Pennant 
- Rock accumulates considerably. It is, however, broken through at Maesteg, which 
lies one mile to the west, by the central uprise of the coal-measures; the lower divi- 
sion of which is brought up to the surface, and worked extensively for the supply 
of three large iron-works. As we proceed more to the westward and approach the 
eastern confines of the Swansea Bay, the Pennant Rock becomes more extensively 
broken through, so that the whole of the lower measures are brought to view, and 
_ workings of a most extensive kind have been opened upon them for the supply of a 
_ large iron-works, rolling-mills, tin-plate-mills and copper-works. 
__ On inspecting Section No. 3, it will be observed that the Pennant Rock stands on 
the north and south side of Cwm Avon, and that the lower measures must necessarily 
_ pass under Margam Mountain and crop out towards the sea. In conformity with 
_ this theory, pits are now being sunk in the neighbourhood of Port Talbot. 
The next Section to which I shall refer is No. 5, from Caswell Bay, in Gower, to 
_ the Great Mountain, in Carmarthenshire, constructed by Mr. Logan and myself, 
_ and published in the Geological Survey. It will now be observed that the uprise has 
- completely removed the continuation of the southern portion of the coal-field which 
exists between Margam and Llantrissent, and the limestone only is to be seen torn 
_ up and contorted in the manner described in the section. Proceeding still more west- 
_ ward through Gower, the limestone is found completely broken up, and the old red 
_ sandstone protrudes through from beneath, which is illustrated in Section No, 6, con- 
structed by Mr. Logan, and which shows a small portion of the lower shales reposing 
_ on the limestone at the western side of Oxwich Bay. 
_ Section No, 4, also constructed by Mr. Logan, from Port Tennant to Castle Cerig 
_ Cennen, is introduced for the purpose of illustrating, by an addition which I have 
made to the section, the probable partiai removal of the coal-measures under 
_ Swansea Bay. 
It would appear, therefore, that the great central uprise of our coal-field, which has 
_ served so usefully to bring up the lower coal-shales in various portions of it, is merely 
_ acontinuation of what has acted with so much more violence in Gower; and that 
_ this movement may perhaps be traced back into Pembrokeshire, where, from the evi- 
_ dence afforded by Sir Henry de la Beche’s valuable surveys, it appears that a great 
disturbance in the limestone and old red sandstone has also taken place. 
I shall now close these remarks by some general observations. The annexed sec- 
tions describe, with sufficient accuracy for general purposes, the governing features 
of the South Wales coal-field; which, from the description I have given, has been 
_ shown to contain enormous mineral wealth. Section No. 1, for instance, exhibits 57 
- feet thick of workable coal; 60 inches of workable argillaceous mine ; and from 18 
_ to 36 inches of black band, all within an attainable depth, averaging a distance by the 
Taff Vale Railway of about 20 miles from the port of Cardiff. One square mile of 
such a coal-field ought to produce, according to ordinary calculations, 40,000,000 tons 
of coal, 8,000,000 tons of mine, and 3,000,000 tons of black band. 
The Swansea Section contains the coal-measures above the Pennant Rock, which 
tay be estimated at 25,000,000 tons of coal per square mile; and to this may be 
idded the last estimate for the coal and mine below the Pennant, which is avaiiable 
or Many square miles at the tops of the valleys, where they are found to crop out in 
roximity with the limestone, and on which all the great iron-works of South Wales 
_ are established. ‘ 
Z y _ The extent of coal-field, therefore, which may be considered available chiefly to the 
“ports of Swansea and Cardiff, may be estimated at about 400 square miles. The 
| South Wales Railway will pass at the foot of all the valleys, so that on its completion 
the whole extent of this country will be in a condition, with the aid of short branches, 
_ tosend its produce to either of these ports. 
___ As regards the qualities of the coals, they may be classed in the following order :— 
bituminous coal, free-burning coal, culm, anthracitic culm, anthracite: for all of 
_ Which there is an extensive consumption. The boundaries of these various qualities 
_ Ihave endeavoured to sketch out on the annexed sections. H 
_ The bituminous and free-burning coal appear to occupy the largest portion of the 
| oal-field, and the anthracite and anthracitic culm the least. The anthracite com- 
| mences slightly at Hirwain, and increases as it advances into Carmarthenshire; and 
in Pembrokeshire the whole of the coal-field partakes of that quality. The other 
