CONNECTION OF MINERAL VEINS WITH VOLCANIC ACTION. 



283 



sionally pass through some of the stratified volcanic grits which have been shown to be 

 contemporaneous with the strata of the Lower Silurian rocks. With these facts before 

 us, there is surely nothing unreasonable in the theory which assumes, that whether these 

 veins have been formed by electricity, galvanism, or other chemical agency, they were 

 intimately connected with volcanic or igneous agency. That the intrusion of volcanic 

 rocks has been one of the principal causes in the production of these veins is, indeed, 

 strikingly apparent from the fact, that in proportion as you recede from these outbursts, 

 the veins become scarcer and finally disappear ; whilst the great mass of them occurs 

 precisely in that portion of the sandstone and shale which is most furrowed by linear 

 eruptions. Again, when we quit the western flanks of this volcanized tract, we leave 

 behind us all the veins, the great undulating Silurian masses of the Long Mountain 

 being entirely exempt from such ; but no sooner do we approach the Breidden Hills, 

 another volcanic chain, than veined stones are once more abundant in the altered and 

 contiguous strata. (PL 32. f. ] .) 



The Stiper Stones. (PI. 32. f. 1,2, and 3.) 



(See the opposite view 1 , and the vignette at the commencement of the chapter.) 



There is not, perhaps, a more singular feature in the physical geography of England 

 than the Stiper Stones. These rocks are made up of a number of broken and 

 serrated ledges, jutting out to form the summits of the hills which flank the vol- 

 canized mining district of Shelve, at heights varying from 1500 to 1600 feet above 

 the sea. They stand out on the crest of the ridge at short intervals, like rugged 

 cyclopean ruins, some of the principal of which are about 50 or 60 feet high, and 

 about 120 or 130 feet in width. The slopes of the elevated moorlands from which they 

 protrude are covered with coarse detritus of the same rock. The main range of the 

 serrated points is from N.N.E. to S.S.W., and therefore conformable to the strike of 

 the adjoining district of Shelve ; but when examined in detail, this ridge is found to be 

 intersected by a number of transverse faults, dividing it into separate masses, some 

 trending 25° and 30°, others only 10° and 15°, to the east of north and west of south. 

 Passages across the ridge are of course most easily made in the hollows between these 

 disjointed " serrse" of quartz rock, as, for example, by the mountain track to the east 

 of the Bog mine. The only fracture, however, which has produced a deep gorge is 

 that by which the river Onny escapes from the upland district of mines. The Rev. 

 John Parker has enabled me to present to the reader, the contrast between this rug- 

 ged mass of quartz rock on the north side of the gorge, and the rich woody demesne 



1 The accompanying view, for which I am indebted to Mr. A. Aikin, was drawn by Mr. Webster, 

 a perfect notion of some of the most northerly of these masses overlooking the vale of Shrewsbury. 



It gives 



