286 



RELATIONS AND ANALOGIES OF THE STIPER STONES. 



Stones has resulted from similar action. For, although in this case the absolute contact 

 of the sandstone with such rocks is not exposed, as at the Wrekin and the Caradoc, 

 linear eruptions of trap are seen on both sides of this massive wall, associated with 

 metalliferous veins and highly altered and contorted rocks. In short, these quartz 

 rocks are encased between two parallels of igneous action ; comprising Pontesford Hill, 

 Habberly, the Cauf Knolls, and Linley, on the east ; Corndon and the Shelve district 

 on the west. That the Stiper Stones are simply sandstones changed into quartz rock 

 is further proved by the recent workings of the Bog mines (the nearest to the mountain 

 side), the horizontal drifts from which, as already stated, when carried in towards the 

 hill, proved that the quartzose mass rises up from beneath in a mural form, cutting 

 off the mineral veins and deflecting them through the overlying schists and sandstones, 

 both to the north and to the south. 



The Stiper Stones are remarkable in another sense, as being the barrier which separates 

 two metalliferous tracts of very different characters. On the west all the veins are of 

 lead ore ; on the east they contain copper and no lead ore. (See the last chapter and 

 PI. 32. figs. 1 and 2.) Comparing small effects with great, this diversity of metalliferous 

 veins on the opposite sides of a ridge of metamorphic rock, is in accordance with a 

 phenomenon observed by Humboldt on the opposite flanks of the great chain of the 

 Ural 1 . 



1 Fragmens Asiatiques. 



