Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/23

 thus that the Five Quarter coal seam of the mines on the Wear is divided into the Metal and Stone-Coal seams of Sheriff Hill, and that the Low-main seam of the Wear becomes the Five Quarter and Six Quarter seams of the Tyne and Gateshead Fell. Thus also in Brandling and Hebburn collieries a parting of stone first divides and afterwards usurps the place of the High Main coal seam; and thus the two upper coal seams that are well worth working (see the section of Montague colliery north) at Kenton, are no longer so in the neighbouring colliery of Killingworth. The following is an account of a similar occurrence in Montague colliery, abridged from an unpublished Memoir, by Mr. Thomas, of Denton, on the dykes found in that mine. Within the Newbiggin Stone-Coal seam, at 20 inches from the floor, there is a band of a soft clayey substance 1$$\scriptstyle \frac 12$$ inch thick: but the band increasing in thickness towards the east, the coal is divided into two distinct seams, whose aggregate thickness is less than that of the original seam. At the distance of 1000 yards to the east, and 300 yards north of the main dyke, the band is 24 feet thick; the upper coal seam 6 inches; the lower 16 inches. The band decreases towards the north at the rate of something more than 1 inch per yard; and the coal at the same time increasing, the upper and lower parts are so nearly united at the distance of 160 yards, as to form again a workable seam. The upper coal then measures 21 inches, the lower 24, and the band 15.

It is useless therefore to attempt any general section of the Coal formation; and it will be seen in the sections subjoined to this paper, how difficult it is from want of uniformity in the beds to identify the coal seams in the vicinity of Newcastle. I refer to the