282 



LEAD VEINS TRAVERSING VOLCANIC GRITS. 



b. The felspar rock is overlaid and underlaid by parallel layers of indurated schist splitting into irregular prisms and 

 rhombs. 



c. Greenstone highly crystalline, very ferruginous on the exterior : it forms the cap of the indurated schist. In a few 

 yards the bedded rock (a) is repeated, having quite a subcrystalline character with crystals of felspar, yet entangling very 

 large fragments of indurated schist. This point is the south-south-western extremity of Mugglewick Hill. 



If we examine the ridges between Mugglewick and the Stiper Stones, we perceive that in the 

 short space of half a mile the inclination of the strata is completely reversed, and that they all dip 

 away from the Stiper Stones at 45° and 40°. In Pell Radeley no distinct signs of stratification can 

 be detected ; masses of hard porphyritic and other felspar rocks appearing through the turf in irre- 

 gularly columnar shapes. These rocks are within 200 or 300 paces of one of the boldest and most 

 broken points of the quartz rock of the Stiper Stones. In the Brook Hill, however, and in the 

 parallel ridge of Ritton Castle (PL 32. f. 2.), trap and shale are as clearly interstratified as any we 

 have mentioned, and both dip at rapid angles to the north-west. The Brook Hill may be considered 

 the prolongation of Cefn-Gwynlle, and in it we see various bedded felspar rocks plunging under 

 those of Ritton Castle. In the latter are thick beds of concretionary felspar rock, passing upwards 

 into felspar breccia like that so often mentioned, and these, after alternating several times with 

 sandstone and shale, are overlaid by highly ferruginous, thinly laminated schists. A vein of lead 

 ore crosses the alternating beds of felspar, breccia, and shale, but does not appear to continue to- 

 wards the mass of true trappean rock ; a gallery was formerly driven in, but is now abandoned. 

 This vein is two to three feet wide, and is directly at right angles to the strike of the strata, which 

 are at this point a little deflected from their regular bearing of N.N.E. to E.N.E. They dip 45° 

 N.N.W. To the north-east these stratified traps of Ritton Castle are lost in the low, wavy ridges 

 which only slightly diversify the arid moorlands, between the mining district of the Bog and 

 Penally on the east, and that of the grit and gravel mines on the west. 



I have thus attempted to give a sketch of the manner in which this district is tra- 

 versed by a variety of veins which are more or less productive of lead ore. In a plan of 

 Mr. More's of Linley Hall, the chief proprietor in this district, upwards of twenty-four 

 are laid down in the district of Shelve alone, excluding the tracts around the Bog and 

 Penally ; so that, comprehending the principal portion of the mining ground, we may 

 say that it contains upwards of thirty metalliferous veins which have been profitably 

 worked. Adding to these the numberless poor and small lead veins in the extremities 

 of the district, and all those which although containing only sulphate of barytes, quartz, 

 and lime, have been produced by the same causes as those which bear lead, we shall 

 find there are few tracts of given extent in any part of the world which are veined to a 

 greater extent. Whilst all the masses of trap rock, whether intrusive or interstratified, 

 range parallel to the strike of the associated strata, viz. from N.N.E. to S.S.W., the 

 metalliferous veins are in most cases transverse or oblique to such direction. In some 

 instances, indeed, they are only very slightly oblique to the strike, as in the Roman 

 vein, but in the great majority of instances they are more obtusely transverse to the 

 prevailing direction of the strata, or radiate as it were across those beds of surrounding 

 shale and sandstone which are contiguous to bosses of intrusive greenstone. In no 

 instance, however, do they continue through the latter. At the same time they occa- 



