[ 110 ] 



XVI. On the Sfritdure and Extent of the Smith Welsh' Coal- 

 basin. By the Rev. W. D. Conybeare, M.A. F.R.S. 

 V.P.G.S. 



To the Editors of the Philosophical Magazine and Annals. 

 Gentlemen, 

 A VERY interesting paper by Mr. Francis Forster on the 

 ■^^ Structure of the South Welsh Coal-basin, &c. has lately 

 appeared in the Transactions of the Newcastle Natural Hi- 

 story Society, a volume which throughout deserves high 

 commendation, as being most creditable to the progress of 

 provincial science; but which is more especially valuable from 

 the importance of the many geological communications which 

 it contains. My own especial object in noticing it, however, at 

 present arises from the circumstance that the author of the 

 very able paper above referred to, whose observations seem to 

 have been confined to the portion west of Swansea, appears 

 to have been unacquainted that I have been long engaged in 

 preparing materials for illustrating this coal-field on the same 

 scale which I have already applied to those of Bristol and 

 the Forest of Dean (vide Geological Transactions). The con- 

 stant accumulation of materials from a district on the border 

 of which I reside, has alone prevented my hitherto completing 

 a memoir on the subject, intended to be submitted, as a com- 

 pletion of my former essays on the South-western Coal-fields, 

 to the Geological Society. But in the summer of 1830, a letter 

 on the subject, addressed by me to my friend Mr.Warburton, 

 was laid by him before the Select Committee of the House of 

 Commons on the Coal Trade : it was printed by them in the 

 Appendix to their Report, p. 394, And as it contains a ge- 

 neral view of my observations on the structure of this district, 

 and appears from Mr. Forster's paper to have been entirely 

 unknown to him, it may perhaps be interesting to some ob- 

 servers of the same field, should it now be reprinted in the 

 pages of your Journal *. 



Truly yours, 



1, Ulster Place, Regent's Park. W. D. CoNYBEARE. 



* In addition to the points mentioned in the following letter, my most 

 important Geological observations on the district, relate to the details of 

 great dislocations affecting the northern edge of the coal-field, between the 

 upper trenches of the Taafe, Neath and Towe : these dislocations gene- 

 rally range east and west, and throw down the limestone and millstone grit 

 many hundred feet, thus occasioning a double outcrop of these formations, 

 with an interval of sometimes nearly four miles. The best example may be 

 seen in the range of highly inclined and curved limestone ranging from Bwa 

 inaen (Vale of Neath) in the direction of Penderin. 



Letter 



