Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/110

92 This district occupies the south-western corner of the county, and contains a greater extent of moor that rises into the Middle zone than any of the others except the first. For 12 miles on the west the Irthing forms the county boundary, with small branches that penetrate the moors on the Northumbrian side. The gritstone edge (Muckle Samuel's Crags) of the watershed between its head and the North Tyne is 1108 feet in elevation, and Whitehill, rather lower down, is 943 feet. Above Wardrew it is a mere moorland stream, but there is a waterfall called Cromel Linn, and lower down to Gilsland the banks are wooded, yielding Saxifraga aizoides, Equisetum variegatum, Galium boreale, and other plants scarcely to be expected at an altitude of between 300 and 400 feet. The pass over which the railway crosses, between the South Tyne and Irthing valleys, is little over 400 feet in elevation, and is the lowest point of the Pennine watershed, which divides the streams of the west from those of the east coast between the Cheviots and the Trent. A moorish swamp called Baron House Bog borders the railway here, and yields Lysimachia vulgaris, Ranunculus lingua, Carex limosa and filiformis, and abundance of Vaccinium uliginosum. Here the Irthing leaves the county to fall into the Eden above Carlisle. The main branch of the South Tyne rises in Cumberland not far from the head of the Tees. At Alston it is 900 feet in elevation, and in the 12 miles that it flows due north it declines on the average 45 feet per mile. Between Knaresdale and Allendale is a ridge of high moor, which reaches 1645 feet on Whitfield Common, and 975 feet over Plainmeller, 2 miles south of the railway. Below the castle and park of Featherstone the Tipple Burn, a considerable stream from the moors on the north, breaks through the basaltic ridge and flowing past the ruined castles of Blenkinsop and Thirl wall, joins the main stream, which turns suddenly due east and flows in that direction 50 miles before it falls into the sea. Between Haltwhistle and Hexham we have what is usually called South Tynedale, a hollow 15 miles in length, with the hills rising from it gradually on both sides. On the north the