220 SEPORT— 1880. 



On the Anthracite Goal and Goal-field of South Walef>. 

 By C. H. Perkins. 



[A communication ordered by the General Committee to be printed in. c.rtensa 



among the Reports.] 



The anthracite or 'stone coal' deposit of the British Islands is confined, 

 with shght exception, to a small portion of the South Wales coal-field. 

 But, limited as it is, it possesses features of an unusually interesting and 

 attractive nature, both in respect to its geological character and the pe- 

 culiar quality of the coal itself. In considering this subject it will be 

 desirable to bear in mind some of the leading features of the coal-field 

 alluded to, of which, as stated, the anthracite deposit forms a part. 



The South Wales coal-field has its eastern boundaiy near the centre 

 of Monmouthshire, and extends from at or near Pontypool in that county, 

 in a westerly direction, until lost in the waves of the Atlantic Ocean, or, 

 more correctly speaking, the Irish Channel, in St. Bride's Bay in Pem- 

 brokeshire. It thus traverses a distance of over 90 miles. To this consider- 

 able length its breadth forms a proportion by no means commensurate, as 

 it nowhere exceeds 21 miles. We are now standing within two or three 

 miles of the southern outcrop of the coal basin, and a crow's flight north- 

 wards of 15 or 16 miles will bring us to the north outcrop in Carmai'- 

 thenshire. The sides and bottom of this great geological valley are 

 composed of mountain limestone, within whicli are piled up the various 

 carboniferous strata to a maximum depth in the centre of over 3000 

 yards. 



This valley or basin is marked by two distinct troughs. The south, 

 the smaller one of the two, extends from the Sirhowy valley on the east 

 to the neighbourhood of Aberavon on the west ; while the larger or north 

 trough reaches from Llanelly through Morriston, Neath, and Blackwood, 

 to Pontypool on the east. The south trougli passes out of the coal mea- 

 sures near Swansea, leaving to the west but one basin, a continuation, in 

 fact, of the north trough, with which, in respect to anthracite, we have 

 alone to do. From the centre of this basin, where the measures lie flat 

 or nearly so, the rise may be regarded for our present purpose as north 

 and south, though in reality nature has not followed minutely these car- 

 dinal points. ' Level course ' would thus run in the main east and west, 

 and, as a rule, the faults cut it in a transverse direction. These faults 

 are frequently of great magnitude, showing at times a displacement up 

 to 200 to 300 yards. 



The quality of the South Wales coal ranges from the pure anthi'acite 

 or ' stone coal ' to the semi-anthracite or Welsh steam coal, and onwards 

 to the highly bituminous or smith's and gas coal. There is also a con- 

 siderable quantity of coal commonly known as ' bastard anthracite,' the 

 quality of which is extremely inferior ; for while debarred of the purity 

 and strength of anthracite, it does not possess the opening or swelling 

 faculty of the steam coal, and decrepitates when burning to an unusual 

 degree. Anthracite or ' stone coal,' with the exception of the Pembroke- 

 shire portion of the coal-field, is found exclusively on the north rise. I 

 use the term ' stone coal ' advisedly, for that of anthracite has, with more 

 or less correctness, been applied to coals which, while bearing an affinity 

 to it, are yet far removed from this, the diamond of the British coal-field, 



