Border Country of Salop and North Wales ; ^c. 245 



and of a flat fan-shaped bivalve, seen also in the indurated clay of Llanvorda. 

 A few casts of nautiUtes, entrochi, and trilobites, also present themselves. 

 Veins of sulphate of barytes pass through the rock, and transparent crystals of 

 the same substance extend into many of the cavities formed by the removal of 

 the shells ; the same cavities contain portions of the black oxyd of manga- 

 nese, sometimes in minute botryoidal concretions, and sometimes diffused over 

 the surface of the quartz in dendritical delineations, and also minute fasciculi 

 of silky crystals of malachite. It ought to be remarked further, that although 

 the rock is full of cavities where it is contiguous to the seams and fissures of 

 its strata, yet the substance of the shells generally remains, and the rock is 

 perfectly solid in the inner parts of its rhomboidal distinct concretions. 



After leaving Norbury, as we proceed northwards for at least seven or eight 

 miles, we again find the slaty sandstone in regular strata : its colour is a deep 

 dull red ; it contains shining particles of mica deposited conformably to the 

 planes of stratification. It is not crystalline, but consists of minute grains of 

 sand, imbedded in a compact, hard, and very ferruginous clay ; the surfaces 

 of its fragments are irregularly triangular or trapezoidal. If the usually re- 

 ceived order of superposition be applicable to this portion of the strata of En- 

 gland, we have here in its proper place the old red sandstone. But, confining 

 ourselves to facts, we do not perceive that this rock differs essentially from the 

 micaceous slaty sandstone, or schistose grauwacke, which has been so often 

 mentioned as occurring through this region, and which geologists have also 

 called Transition Slate *. 



The Stiperstones Mountain is a long and steep ridge situated to the west 

 of the tract of the red schistose sandstone just described; its direction is N. 

 and S., and along its summit are seen large weather-worn masses of a cherty 

 sandstone and of a siliceous conglomerate. Both of these rocks have the cha- 

 racters of the strata belonging to the millstone grit formation ; the masses of 

 cherty sandsone have a distinct stratification, the planes of which are now 

 nearly vertical, proving them, notwithstanding their singular position along the 

 ridge of a lofty hill, to be the displaced fragments of a more ancient and regu- 

 lar formation. At the bottom of this mountain and near its north-western 

 extremity is situated the Snaifbach lead-mine, which is worked in the slate, 

 and is described by Mr. Arthur Aikin in the fourth volume of the Geological 

 Transactions. A few miles further north rises Pontesford Hill, terminating 



* In Scotland the strata, which are seen about Lanark, at Cartlane Craigs, and the Falls of 

 Clyde, correspond with those in the district of Shropshire described in the present paper. 



