12 A NEW FLOBA OF 



out from beneath the Millstone Grrit; it caps some hills near 

 AUenheads, and forms the summit of Middle Fell in Cumber- 

 land : it is fossiliferous, and I have found in it Productus senii- 

 reficulatus, Spirifer lineatm, Strophomena rhomloidalis, Orthis 

 Michelini. The third, the Great Limestone, from 54 to 66 feet 

 in thickness, is the most important of all, being more produc- 

 tive 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 Pell ; it bassets out on the north bank of the Tees and 

 near Prosterley, and dips below the bed of the Wear. Its effect 

 on the soil is conspicuous, and has been well described by Mr. 

 Sop with. "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 cha- 

 racter 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 E'ent Porce. The Cockle Shell Limestone, a thin 

 bed of only 2 feet, abounds in fossils, among which is Productus 

 giganteus, 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 south- 

 ward over the banks of the Tees into "Westmorland. The lime- 

 stones 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 



* Sopwith " On the Mining District," p. 4. 



