A HISTORY OF STAFFORDSHIRE CARBONIFEROUS SYSTEM We have seen that the geological history of Staffordshire presents, in the absence of the Old Red Sandstone, one of those tantalizing breaks so frequent in the imperfect record of the rocks. The missing chapters are found in Worcestershire, Herefordshire, and in South Wales, where the lacustrine deposits of the Old Red Sandstone indicate an elevation of the Silurian sea floor and the subsequent formation of large fresh- water lakes. So great was the time represented by the missing period that the fauna of the Carboniferous strata the next group met with has a totally distinct aspect : many new orders, many new genera make their appearance, while the species differ from those of the Silurian seas ; the vertebrata have increased in numbers and are very much more highly organized. The Carboniferous system commences abruptly with the marine conditions of the richly fossiliferous Mountain Limestone of North Staffordshire, when the ocean waters were warm and clear, and coral reefs, on which flourished a prolific marine fauna, extended their fringes along the coast line. A large river then appears to have entered the sea driving away the corals and many other life forms, and laying down first the muds and grits of the Pendleside Series, and then the grits and shales of the Millstone Grit period. Ultimately a delta appears to have been formed in which, or along its margins, the muds, shales, sandstones and numerous seams of coal constituting the Coal-measures, were deposited. The Carboniferous rocks stand out boldly above the Triassic plain in the North and South Staffordshire Coalfields. Though separated from each other by the intervening red strata, it is now almost beyond dispute that these isolated coalfields are connected underground. Local inter- ruptions there may be, such as are shown at the surface in the Silurian hills of Dudley and Walsall, but recent borings and shaft-sinkings to the east and west of the present outline of the South Staffordshire Coalfield prove conclusively the extension of the Coal-measures in these directions; while the identity of the Coal-measure sequence as a whole in North and South Staffordshire is strongly in favour of the sediments having been deposited in the same basin. The exact nature of the pre-carboniferous floor has not been ascer- tained, but the thinning away and final disappearance of the individual members of the system, when traced from the north-north-west to the south-south-east, shows it to have sloped rapidly upwards to the south- south-east, and at a still greater rate due south. Thus the southern area appears to have lain above water during the long period represented by the great thicknesses of the Carboniferous Limestone, Pendleside Series and Millstone Grits of the north, and not to have been submerged until Coal-measure times. The filling up of the basin and its submergence does not appear to have been a simple process, for a study of the Carboniferous rocks of the Midlands, especially in North Staffordshire, clearly shows that the period 6
