106 Mr. F. Forster's Observations on the South Welsh Coal Basin. 



which stands Llwchor Upper Town ; from hence the strata appear to 

 change their incHnation and dip southwards, until concealed under the 

 marsh, the western part of which is crossed by our line of section. 



Assuming that this contortion extends under the sands to the west- 

 ward and equally affects the strata in the line, the real depth between 

 the Carnarvon seams and the first of the next series, called the " Ban- 

 cog Seam," will be much less than would otherwise be inferred from 

 the distance between them, if, indeed, a down-throw Dyke to the south- 

 ward, of considerable magnitude, do not intervene ; an occurrence 

 strongly indicated by the contortion of the strata already noticed, by 

 the great inclination of the Bancog and subordinate seams, as compared 

 with those at Carnarvon and Llwchor Collieries, and by the non-exist- 

 ence of any other seams of Coal on the north side of the centre which 

 will at all correspond to the six seams cropping out on the Marsh. The 

 first and second of these seams, the " Bancog and the Fraith" are, I be- 

 lieve, of inferior quality, the next three have been proved by the sinking 

 of the Dunraven Pit, at the Adair Colliery, about one mile to the east of 

 the line. The first of these, called the " 9-Feet Seam" (although it is in 

 reality 11 feet in thickness) is a very pure Bituminous Coal, but soft and 

 friable in its texture ; it was intersected at the depth of 40 fathoms. The 

 next, the "Glo-braisc" or Big Coal Seam, Q5 fathoms below the 9-Feet, is 

 4<i feet in thickness j it is more bituminous, and approaches more nearly to 

 Newcastle Coal, both in quality and texture, than any other Welsh Coal 

 that I have seen. Ten or twelve fathoms below this the Yard Seam oc 

 curs, and a few fathoms lower a seam of inferior Coal, 2 feet in thick- 

 ness, crops out. The strata in the Dunraven Pit, to the depth of 40 

 fathoms, dip at an angle of 30°, or about 42 inches per fathom ; here the 

 9-reet Seam after being intersected by a slip 6 feet down to the north- 

 ward, dips about 22J°, or 30 inches per fathom ; the deeper seams, owing 

 to the hade or underlay of this slip to the northward, will be intersected 

 by it considerably to the dip of the Dunraven Pit, and their inclination 

 will, in all probability, undergo the same change. These seams con- 

 tinuing their range to the eastward by way of Ystrad, Mynydd-bach-y- 

 Glo {i. e. the Little Mountain of Coal), pass to the northward of the 



