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 20,000 feet. 
Fossils were first discovered in these beds * in 1856, by Mr. Salter, 
Palaeontologist 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 
P'ortway, 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 wheu men wondei-ed 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 Oldlianiia', fouiKl in 1847 liy Dr. Kinahan in the Cambrian rocks of Bray 
Head, were tiie fu\st relics found in the Cambrian rocks. Of these we shall speak 
presently. Burrows of Annelides have also been obtained at Bray Head by Dr. 
Kinalian ; one trumpet-shaped form of which from thence has been named by that 
gentleman Bistiodcrma Hibernica. 
