Page:Transactions of the Natural History Society of Northumberland, Durham, and Newcastle-upon-Tyne (1867).djvu/49

Rh yellow sand; but it is not seen either underlying or penetrating the Magnesian Limestone, which caps the same cliff a little to the northward of the dike. It is 12 feet wide, and runs in the direction of south 40° east to north 40° west, with a slope southward of 85°. The dikes we have noticed are basalt, but this is more allied to greenstone or diorite.

The Coaly Hill Dike varies in width from 7 feet to 21 feet, and has a general direction of E.S.E. It seems to be the same as that which comes to the surface at Ouseburn, and at Simonside, in the county of Durham. Buddle has described it, and notices, that it pursues an undulating course, only occasionally appearing on the surface. In Benwell colliery it is 200 feet, and in Walker colliery 630 feet below the Tyne level. The coal in contact with it is reduced to "cinder."

Two small dikes with an east to west direction, about 13 feet apart, one being 5 feet and the other 6 feet wide, dipping north 78°, are in Walbottle Bene: these have the character of greenstone.

The Brunton Dike, on North Tyne, which cuts through the Mountain Limestone beds from north 40° east to south 40° west, is 16 feet wide, and throws down the strata on the west side above 20 feet. It crosses the South Tyne passing Warmley, and probably extends to Whitfield, where a basaltic dike is seen on the West Allen.

The Lewis Burn Dike has a long and somewhat irregular course, but with a general direction of east north-east; and it is traceable from Short Cleugh, on Lewis Burn, to Troughead and Darden, in Redesdale, a distance of 12 miles. At Short Cleugh, in the deep gullies made by water torrents, this dike is exposed at several points; it widens as it descends, and attains the width of 50 feet; a small branch comes from the main trunk, and is seen in the hill side. The Mountain Limestone strata, which it cuts through, are greatly dislocated; on its south side sandstone beds are flat, while on the other they are nearly perpendicular.

Of the two principal basaltic dikes in Durham we have some definite information.