328 



ABSURD TRIALS FOR COAL IN ALTERED SILURIAN ROCKS. 



inhabitants of this dingle, and galleries have been driven horizontally through these inclined beds 

 in search of coal. A transverse section from this spot to the chief focus of eruption around the 

 Gelli exhibits at least two other distinct small ridges of trap (porphyritic greenstone and felspar rocks) 

 alternating with shale. At Tin-y-coed, I found a credulous farmer ruining himself in excavating a 

 horizontal gallery in search of coal, an ignorant collier being his engineer. This case may serve 

 as a striking example of this coal-boring mania in districts which cannot by possibility contain 

 that mineral, and a few words concerning it may, therefore, prove a salutary warning to those who 

 speculate for coal in the Silurian Rocks. 



Tin-y-coed. 58. 



a. Trap. b. Black schist. b*. Schist altered in contact with trap. c. The gallery. 



The farm-house of Tin-y-coed is situated on the sloping sides of a hill of trap (a), which throws 

 off, upon its north-western flank, thin beds of black greywacke shale (b), dipping to the W.N.W. at 

 a high angle. The colour of this shale and of the water which flowed down its sides, the pyritous 

 (sulphureous) veins and other vulgar symptoms of coal-bearing strata, had long convinced the farmer 

 that he possessed a large hidden mass of coal, and unfortunately a small fragment of real anthracite 

 was discovered which burnt like the best coal. Miners were sent for, and operations commenced. 

 To sink a shaft was impracticable, both from the want of means and the large volume of water. A 

 slightly inclined gallery (c) was therefore commenced, the mouth of which was opened at the bottom 

 of the hill on the side of the little brook which waters the dell. I have already stated that in many 

 cases where the intrusive trap throws off shale, the latter preserves its natural and unaltered con- 

 dition to within a certain distance of the trap ; and so it was at Tin-y-coed, for the level proceeded 

 for 155 feet with little or no obstacle. Mounds of soft black shale (b) attested the rapid progress 

 of the adventurers, when suddenly they came to a "change of metal." They were now approaching 

 the nucleus of the little ridge, and the rock they encountered was, as the man informed me, " as 

 hard as iron," viz., of lydianized schist (b* of wood-cut), precisely analogous to that which is ex- 

 posed naturally in ravines, where all the phenomena are laid bare. The deluded people, however, 

 endeavoured to penetrate this hardened mass, but the vast expense of blasting it put a stop to the 

 undertaking, not, however, without a thorough conviction on the part of the farmer that, could 

 he but have got through that hard stuff, he would most surely have been well recompensed, for it 

 was just thereabouts that they began to find "small veins of coal " ! 



It has before been shown that portions of anthracite are not unfrequent in the altered shale 

 where it is in contact with intrusive rock. And the occurrence of the smallest portion of anthracite 

 is always sufficient to lead the Radnorshire farmer to suppose that he is very near "El Dorado V 



The western side of this longitudinal valley of Tin-y-coed or Cwm mawr is bounded by loftier 

 hills, on the flanks of which is much altered and contorted rock ; with some points of eruptive trap. 

 In the central district of Gelli, are many appearances of conformable alternation of shale with trap 

 and porphyritic flags. The north-western branch of this region ranges to the prominent rock of 



1 Amid all their failures I never met with an individual who was really disheartened; a frequent exclamation 

 being — " Ah ! if our squires were only men of spirit we should have as fine coal as any in the world." 



