MINERAL BASON IN WALES. 3gJ 



VII. 



Description of the Mineral Bason in the Counties of Mon- 

 mouth, Glamorgan, Brecon, Carmarthen, andJPembrokc. 

 By Mr. Edward Martin. Communicated by the Right 

 Hon. C. F. Grenville, F. R. S* 



1 i HE irregular oval line, delineated on the annexed Limestone ba- 

 map (Plate IX.) shows nearly the inner edge of a little- ^IfjJw^Srmof 

 stone bason, in which all the strata of coal and iron ore«>aland iron 

 (commonly called iron stone) in South Wales are deposited; \Vales 

 the length of this bason is upwards of 100 miles, and the 

 average breadth in the counties of Monmouth, Glamorgan, 

 Carmarthen, and part of Brecon, is from 18 to 20 miles, 

 and in Pembrokeshire only from 3 to 5 miles. 



2. On the north side of a line, that may be drawn in an On the north 

 east and west direction, ranging nearly through the middle ° he stn^ti^e 

 of this bason, all the strata rise gradually northward ; and to the north, 

 on the south side of this line they rise southward, till they lout j l t0 the 

 come to the surface, except at the east end, which is in the south, 

 vicinity of Pontipool, where they rise eastward. 



3. The depths from the surface to the various strata of Depths from 

 coal and iron ore depend upon their respective local situa- vary< 

 tions. 



4. The deepest part of the bason is between Neath, in Deepest part 

 Glamorganshire, and Llanelly, in Carmarthenshire; tne u ^etmott" 

 uppermost stratum of coal here does not extend a mile in stratum. 



a north and south direction, and not many miles in an east 

 and west direction, and its utmost depth is not above 50 or 

 CO fathoms. 



5. The next stratum of coal, and those likewise beneath Second and 

 it, lie deeper and expand still longer and wider, and the iower strata. 

 lowest which are attended by parallel strata of iron ore, 



of which there are in some situations about 16 accompanied 

 by irregular balls or lumps of iron ore, tfecupy the whole 

 space between Llanmaddock Hill, near the entrance of 

 Burry river, to Llanbidie, from the Mumbles to Cribbath, 

 from Newton Down to Penderryn, from Castle Coch to 

 Castle Morlais, and from Risca to Llangattock, and in 



* From the Philos. Trans, for 1806, p. 342. 



length 





