Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/28

12 out from beneath the Millstone Grit; it caps some hills near Allenheads, and forms the summit of Middle Fell in Cumberland: it is fossiliferous, and I have found in it ', ', ', '. The third, the Great Limestone, from 54 to 66 feet in thickness, is the most important of all, being more productive of lead than all the other strata united; it forms the bed of the Aleburn for some distance, and climbs the mountain brow of Ale Fell; it bassets out on the north bank of the Tees and near Frosterley, and dips below the bed of the Wear. Its effect on the soil is conspicuous, and has been well described by Mr. Sopwith. "Its basset," he says, "forms, in many instances, the limit of cultivated land and of human habitations. Below it the hill sides, in spring and autumn, present a beautiful green surface, and in summer an abundant and flowery produce in the meadows; while on the same hill, above the limestone, bare short grass, ling, and moss, impart the brown dreary aspect which characterizes all the higher portion of the mining district, rendered in moist weather or in winter still more dreary by hanging mists on the summits, or wasting snows scattered over the wide expansive sides of the hills, but from the massive character of the scenery, rendered beautiful and even sublime by the blue shades of evening, or the subdued effect of moonlight." The Scar Limestone, which has a thickness of about 54 feet, appears in Weardale and Teesdale: for some distance it is the roof of the level into the mine at Alston, and it forms a romantic waterfall at Nent Force. The Cockle Shell Limestone, a thin bed of only 2 feet, abounds in fossils, among which is, a form distributed throughout the whole formation. Over the Tyne bottom Limestone, which is 24 feet thick, and the lowest in this district, the river runs from the Tyne head for 4 miles; and this bed, along with the strata above it, extend southward over the banks of the Tees into Westmorland. The limestones below this, among which is that of Melmerby Scar, crop out, beyond our district, in Cumberland and Westmorland.

With our present materials we cannot correlate the Mountain