184: THE GEOLOGIST. 



of Shrewsbury, or, trending southward, water the country between 

 Bishop's Castle and Ludlow. 



The lowest strata of the Longmynds range along the western side 

 of the Stretton valley, and consist of thin, fragile, glossy schists, or 

 clay-slate, with two or three minute layers of siliceous limestone, of 

 scarcely more than an inch in thickness. These beds, partially inter- 

 fered with by bosses of eruptive trap-rock^ dip to the west-north-west, 

 and are overlaid by a vast and regular series of hard purple or plum- 

 coloured, greenish, and grey schistose flagstones and siliceous grits. 

 Quartz-veins occur here and there, but on the whole the mass 

 consists of schistose and gritty sandstone, often finely laminated, and 

 scarcely at all affected by slaty cleavage. These highly inclined beds 

 are overlaid in the direction of their dip by other masses of purple 

 sandstone, conglomerates, and schists, of very considerable dimensions, 

 the highest of which pass conformably under the Stiper-stones and 

 other Lower Silurian strata. The thickness of these Longmynd rocks, 

 as taken at the out-crop of their highly-inclined edges, is stated by 

 the Government surveyors at 26,000 feet. 



Fossils were first discovered in these beds* in 1856, by Mr. Salter, 

 Palssoutologist of the Geological Survey, in nearly vertical beds of 

 hard flaggy sandstone, occurring along the strike of the Longmynds 

 about a mile and a half east from the principal ridge, and which form 

 part of a series of bluish-grey sandstones, alternating with purplish 

 slaty beds, lying below the conglomerates and red-sandstones of the 

 Portway, and above the thick series of dark-olive schists exposed at 

 Church Stretton. 



From the upper olive shales (Lign. 1, Stratum 2) to the hard grey 

 grits of the Portway (Stratum 8), through a series of beds of more 

 than a mile in thickness, the ripple- and worm-marks are conspicuous. 



The time was when men wondered at the strange forms which 

 nature produced in the quarries and in the rocks, and assigned super- 

 stitious tales and qualities to such natural phenomena. The past 



* The Oldhamire, found in 1847 by Dr. Kinalianin the Carabrian rocks of Bray 

 Head, were the first relics found in the Cambrian rocks. Of these we shall speak 

 presently. Bnrrows of Annelides have also been obtained at Bray Head by Br. 

 Knialian : one trnmpct-shaped form of which from thence has been named by that 

 .uontloman Ilisdodcrma Hihcrnica. 



