NORTHUMBERLAND AND DTJEHAIT. 93 



most striking feature is the basaltic dike, which in some places 

 reaches a height of 700 or 800 feet above sea-level, forming a 

 decided ridge across the moor from west to east, with an escarp- 

 ment towards the north which, in several places, consists of a 

 cliff 20 or 30 feet in depth, as at Kyloe, with great heaps of an- 

 gular slate-coloured basaltic debris scattered over the embankment 

 below it. For several miles along the top of this ridge, with 

 nothing on either side but heathery moor, the Roman wall is 

 carried, following the irregularities of the ridge with pertinaci- 

 ous adherence. Rising from the Black Burn west of Peather- 

 stone Castle, where the water, after running for some distance in 

 a deep and narrow channel is thrown over a columnar cliff in a 

 succession of falls, from which the broken sedimentary rocks dip 

 at every angle, and from the wild ravines called the Nine ISTicks 

 of Thirl well, between the Tipple and Haltwhistle Burns, the 

 ridge forms Wall Town Crags and Cockmount, and thence sweeps 

 with a slight tendency towards the north by way of Sewing 

 Shields, Black Bank, and Crag Lough, in the direction of Wall 

 and Gunnerton. Crag Lough is a tarn half a mile in length, 

 with a fine cliff of the kind just alluded to rising up from the 

 water's edge on the south side. Muckle Moss is a large swamp 

 upon the hill slope 2 miles to the south-east, which is well-known 

 as a botanical station. By means of the Newcastle and Carlisle 

 Railway this tract is all brought within the compass of a day's 

 excursion from Newcastle. Round the head of the two branches 

 of the Allen for 10 miles a continuous ridge of high heathery fell 

 forms the watershed between Tyne, Wear, and Derwent. The 

 highest points are near the centre — Kilhope Law, 2206 feet, and 

 Stangend Rigg, 2074 feet; but for the whole 10 miles the ridge 

 scarcely sinks below 1700 feet, and the spurs in a northern direc- 

 tion maintain a sufficient height for several miles to give East 

 and West Allendale more of a decided dale character than any 

 other of the Northumbrian valleys. This is well known as a 

 rich mining tract. The limestone is thrown down to the level of 

 the river in the western, and below the level in the eastern 

 hollow in the upper part, so that the higher reaches of the main 

 streams have very little to diversify them, and the hills are 



