Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/204

 192 three or four miles above Bridgenorth, and accompanies its course to Wire forest, the extreme south-eastern point of the county. The eastern limit of this tract extends into Staffordshire, approaching within a few miles of the county-town, whence it proceeds south to the village of Tettenhall near Wolverhampton, and then passes by Kidderminster to beyond Droitwich.

This rock consists for the most part of rather fine grains of quartz with a few spangles of mica, cemented by clay and oxyd of iron. Its colour is generally brownish-red, and it has but little cohesion; on which account large tracts of loose deep sand are found in many parts of it. Sometimes it occurs nearly of a cream colour, and is then sufficiently hard to form an excellent building stone: it does not effervesce with acids, and, to the best of my knowledge, never contains shells or other organic remains. Rolled stones of quartz, of granite, of greenstone-porphyry, and of other primitive rocks, are found dispersed over its surface and imbedded in the loose sand, but are rarely, if ever, observed at any considerable depth in the solid rock. It rises at an angle of 10° or 12° between S. and S.W. At Alderley Edge in Cheshire, it is mixed with grey oxyd of cobalt, and contains veins of heavy spar with galena and yellow copper ore; and is tinged green by oxyd of copper at Hawkestone, at Pym-hill, and elsewhere in Shropshire. The salt deposit of Northwich, and the salt-springs of Droitwich, of Adderley near Drayton, and of Admaston and Kingley-wich near Wellington are subordinate to this formation. Its southern extremity in Shropshire rests upon highly elevated strata of grauwacke. It is covered in several places by thin strata of sandstone-slate, which passes into slaty marl containing shells: these beds rise in the same direction as the sandstone on which they rest, but with an angle rarely exceeding 6°. The general face of this tract is an undulated country, having usually the southern declivities