86 Mr, F. FoRSTEu's Observations on the South Welsh Coal Basin. 



and the Forest of Dean, but their remarks on the South Welsh 

 Coal-field do not extend beyond the observations necessary to establish 

 its connection, as resting on the same general basis of Old Red Sand- 

 stone, with the former districts ; and, a variety of remarks, accompa- 

 nied by a section from Brecon to the Bristol Channel, pointing out, in 

 a most striking manner, the relative positions of the Old Red Sandstone, 

 Limestone, and Coal Measures, and of the unconformable and overlying 

 masses of Magnesian Limestone, New Red Sandstone, and Lias, in the 

 vale of Ely, near the eastern termination of the Basin. 



The observations I am about to offer, are of a more practical nature, 

 have a diiferent object, and principally refer to a different part of the 

 Coal-field from all these, otherwise I should not have ventured upon a 

 subject which has passed through such able hands. I shall, after at- 

 tempting to convey a general idea of the extent and position of the beds 

 forming this Basin, confine my remarks to the nature and quality of its 

 various seams of Coal, and to a description of the strata in those particular 

 portions of the counties of Carmarthen and Glamorgan, across which 

 my line of section passes. 



RANGE AND EXTENT OF THE WELSH BASIN. 



On referring to Greenough's Geological Map, it will be observed, 

 that this Coal-field extends in an east and west direction in the form 

 (to use a familiar simile) of a long-necked flask, from Pontypool in 

 Monmouthshire, to the Irish Channel on the coast of Pembroke ; the 

 western end or neck (about 2i miles in width) commences at St. Bride's 

 Bay, and extends across that county to the eastward about 28 miles, 

 where it is cut off, at Pendine on its northern, and at Tenby on its 

 southern edge, by that part of the Bristol Channel forming Carmarthen 

 Bay ; its width at the point where it is thus intersected having increas- 

 ed to about 6 miles. The Coal Measures continue their range to the 

 eastward across this Bay, and on again entering the land forming its 

 N. E. side, their width from north to south is about 10 miles. About 

 10 miles to the eastward, and at a point which may be termed the 

 shoulder of the flask, in width about fifteen miles, the section 



