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 A HISTORY OF STAFFORDSHIRE Barr and Netherton anticlines, between which lie the faulted synclines of Bilston, Corngreaves and Pensnett. The coalfield is completely surrounded by the unconformable Triassic rocks, underneath which it slopes gradually on the south and north, and against which it is faulted on the east and west by the great ' Boundary Faults.' The suc- cession consists in the main of a replica of that in North Staffordshire, but it is doubtful if the district came within reach of the Carboniferous waters until a considerable portion, if not the whole, of the Lower Coal- measures of North Staffordshire had been deposited. The Carboniferous Limestone, Pendleside Series and Millstone Grits are certainly absent, the Coal-measures being deposited on an irregular floor of Silurian rocks visible at the surface in the Dudley, Walsall and Sedgley areas, but also encountered underground between West Bromwich and Oldbury, where they constitute the so-called ' Silurian bank.' Lower or 'True Coal-measures. 1 In composition the strata (500 to 1,050 feet thick) resemble the chief coal-bearing rocks of North Staffordshire, consisting of grey and white sandstones, shales, clays, ironstones and seams of coal. The most remarkable of the seams known as the ' Ten Yard ' or ' Thick Coal,' underlies Smethwick, Dudley, Walsall and Bilston, and was formerly quarried in the open near Tipton. It is not an undivided stratum of coal, but is made up of thir- teen or fourteen distinct layers separated from each other by thin partings of shaly material or ' bat.' South of Halesowen it thins out and becomes mixed with shaly matter ; but what is more remarkable when traced northward the component seams gradually separate until at Essing- ton and Pelsall the Thick Coal is represented by fourteen seams lying in a mass of shales and sandstones between 250 and 300 feet in thickness an excellent example of the unequal rate of sedimentation under which the Coal-measures were deposited. The Thick Coal has been proved to extend beyond the visible limits of the coalfield, having been recently encountered beneath the Red Rocks to the west at Himley, while it is being worked under the same formation to the east in the Sandwell Park and Hamstead Collieries. Again, to the north of the coalfield, pits have been sunk through the ' Pebble Beds ' of Cannock Chase, and a new coalfield developed in this direction. The scenery of the South Staffordshire Coalfield is aptly described under the name ' Black Country.' The original surface features over wide areas are not only entirely obliterated by refuse heaps and grimy manufacturing towns and villages, but over all there rests, day and night, a canopy of black smoke. In past years a large quantity of local ironstone was raised, but at the present day the greater bulk of the ore for use in the iron furnaces comes from Northamptonshire, the Potteries and elsewhere ; but it was the presence of iron ores, in conjunction with large quantities of cheaply 1 The title assigned to the Coal-measures of South Staffordshire by Prof. Lapworth. Vide A Sketch of the Geology of the Birmingham District, Geologists' Association (1898). 16