TRIALS FOR LEAD ORE, ETC., GREAT ADIT. 



281 



the strike of all being persistently to the N.N.E. The most marked of these hills are Cefn-y- 

 Gwynlle, the Bank, Mugglewick, Radely, and Ritton Castle. Cefn-y-Gwynlle, which rises to a 

 height of 1100 feet, is composed of greenstone and grey felspar rock (a sort of pseudo porphyry), 

 the latter passing into what has been called volcanic breccia, large masses of which are interlaced 

 with some schistose beds, and throw off others upon their flanks. This hill is full of small and poor 

 mineral veins which traverse the strata, and numerous trials have been made in various parts. One 

 of these trials was in progress from the western flank of the hill when I first visited the district 

 (1832). A gallery had been driven across the inclined strata and passed through the following 

 rocks : 



Yards. 



1. Trap, consisting of greenstone made up of common felspar and hornblende with much carbonate of lime; 



slaty in parts , 40 



2. Brecciated rocks 20 



3. Thinly foliated black shale with white quartz veins 10 



4. Compact flaggy felspathic rock (Query, indurated shale or compact felspar rock?) 40 



5. Trap; greenstone with crystals of hornblende and felspar ; lime disseminated 12 



6. Indurated schist, with many veins of quartz, containing crystals of iron pyrites. (Here a vein of lead ore 



was met with.) 120 



7. Vein stuff, containing sulph. of barytes, calcareous spar, and a little lead ore. This vein was very thin, 



and being followed out to the north-east disappeared In a mixed shaly rock. The work proceeded again 

 in the same matrix as No. 6. but the trial entirely failed 1 . 



Near the Rynis Gate, a cut recently opened by the new road has exposed a succession of trap- 

 pean masses alternating with indurated schist in the following ascending order, and dipping E.S.E. 

 at an angle of 40° to 45°. 



a. Thick beds of felspathic breccia, containing fragments of indurated schist with crystals of iron pyrites ; some of these 

 pass into layers of grey and whitish colours so purely felspathic that no foreign ingredient can be detected : all the beds 

 cleave in the direction of the planes of lamination. 



1 The most decisive proofs of the subterranean existence of alternations of trap and shale have been met 

 with in driving a tunnel to drain this wet and upland mining tract. The tunnel opens into the low country 

 near Leigh Hall, and as its course thence is to the south it necessarily traverses in a slightly oblique direction 

 all the alternating masses of rock which are interposed between its mouth and the mining ground. These 

 alternating masses are in fact the very rocks we have been just describing, and rise to the surface in the Cal- 

 lows, Notmoor, and Lordstone Hills. In 1835 the work had proceeded upwards of a mile from its mouth, and 

 had passed through the following rocks : 



Yards. 



1. Shale, &c 120 



2. White rock (the China stone described) 4^ 



3. Trap 56 



4. White rock, as above (altered sandstone, &c.) ... 6 



5. Trap 114 



6. Shale and Sandstone 124§ 



7. Trap 297J 



Yards 



8. Shale ; 6 



9- Trap 6 i 



10. Shale j 3 



11- Trap us 



12, Shale, &c 987 



Yards 1977* 



As this level had been for some years in progress, I had not an opportunity of examining the precise nature of 

 all the different rocks which were traversed. From the external features of the intervening tract which re- 

 mained to be perforated, it is probable that most of the hard rocks have been already cut through, and that the 

 work would reach the mining ground with few additional obstacles. This adit is seven feet high, and six feet 

 wide. 



