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 GEOLOGY As a whole it covers a tract ot country thirty-two miles long from east to west, and averaging six miles in breadth.' To the north it runs out upon the Lower Coal Measures, to the south it dips under a narrow band of Permian sandstones and marls, the whole being faulted down beneath the Trias of the Cheshire plain, which extends into the margin of the coalfield in a few broad triangular tongues. To the east, as to the north, the measures run out upon the Lower Series, whilst to the west they are faulted down to a great depth under the Trias, which here forms a low, flat maritime plain. Although it would thus appear that the coalfield is compact, yet faulting and denudation have been so extensive that no complete correlation of the coal seams has yet been established. Whilst also some of the seams are fairly persistent, others thin or swell out, whilst hundreds of feet of shale in one place are represented by a few feet of sandstone in another. It is possible that some of the thicker and more valuable coals are persistent over a great part of the coalfield, being known under different names in different districts, and altering somewhat in their character. The extreme east of the coalfield we may define as the (A) OLDHAM AND DUKINFIELD AREA The best general section is that given by Professor Hull ^ and reproduced here. Coal Series of Oldham and Middleton Bardsley Colliery Ft. In. Ft. 45 I ' Bardsley Rock ' Sandstone. . Shale Stubb's Mine (Coal) .... Metal (Shale) 25 Fairbottom Mine 2 Shale, with three thin seams of coal 76 Park Mine (coal, with parting of clay) 3 Shale29ft.,Foxhole'srock79ft.8in. 108 Foxhole's Mine 2 Soft Metal 32 Cannel i Strata, principally shales, with a coal seam 16 inches. . . 187 Hathershaw Mine 2 Shale, with two seams of coal. . 51 Rock and rock bands, with water (Chamber rock) 88 Shale and sandstone 38 Nield or Upper Chamber Mine (sometimes absent). Shale and Sandstone .... Lower Chamber Mine : Coal, I ft. 5 in Dirt, o ft. 4 in Coal, I ft. 2 in Dirt, o ft. 8 in Coal, o ft. 8 in 2 54 Ins. 6 7 5 6 o 6 6 8 4 6 6 2 o 6 3 o 6 76 33 2 66 Blenfire Coal : Coal and cannel, i ft. 11 in. . Dirt, o ft, 6 in. (very variable) Coal, o ft. 1 1 in. . . Dirt, o ft. II in. . . Coal, o ft. 9 in. . . Sandy Shale and shale Great Mine : Top coal, I ft. 1 1 in. . Clay, o ft. 5 in. . . . Coal, 3 ft. 6 in. . . . Clay, o ft. I J in. . . Bottom coal, 4 ft. o in. Sandstone with shale, with shells. Little Coal Sandstone and shale with fish remains Black Mine (the best seam in the district) 4 Shales, sometimes strong with two coal seams 117 Stone Mine ; Top coal, o ft. II in. . . . | Stone, I ft. 2 in. (roof dark stone ') ) 3 Bottom coal, i ft. 3 in. . . ) Soapstone (sandy shale), with a band of white rock Upper Bent Mine Hard Soapstone, with ferns. . . Lower Bent Mine Strata HoUingworth Coal Strata 234 Neddy Mine 2 Strata, with several thin coals, about 441 Roy ley Mine (with a parting of shale) 4 21 2 29 2 37 I IDs 4 2 8 8 6 6 o 6 o o Glodwkk Colliery Shale and bands of sandstone. . 66 c Red sandstone, with plants (Blenfire Rock) 146 9 The two sections are practically continuous, the interval between the base of the Bardsley Colliery section and the Blenfire rock of Glodwick being occupiedby a series of shales and sandstones. 1 Hull's Coalfields of Great Britain, ed. 4 (1881), p. 197. 2 'Geology of the Country around Oldham,' Mem. Geol. Survey, p. 24, 1864. 15