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GEOLOGY core of the hills consists of the lower shales ; the flanks of the two beds of limestone with their intervening shales and overlying Ludlow Shales. Owing to their purity and excellence as a flux, their proximity to the blast furnaces, and to the high inclination rendering the extraction of the stone a cheap and simple process, the limestones have been quarried for many centuries. This industry was sufficiently striking to attract the attention of Dr. Plot in 1686, who also unmistakably figures some of the common fossils. At the present day the underground excavations extend for great distances and to considerable depths into the heart of the hills, beneath which they form vast gloomy caverns, through which there wanders a long canal used in the transportation of the quarried stone. Fossils abound, some thin layers of the limestone being crowded with organic remains corals, brachiopods, bryozoa. The district has become especially famous for the extremely beautiful and extensive series of crinoids (stone-lilies) and for the excellent preservation and large number of trilobites which have not only enriched several local collections, but have found their way into many cabinets abroad. Ludlow Shales and Aymestry Limestone. At Walsall the Wenlock limestones are succeeded immediately by the unconformable Coal-measures, but around Dudley Castle they pass up into bluish grey shales belonging to the Ludlow sub-division, which in turn become covered up by Coal- measure strata. In the Sedgley inlier the upward sequence is further continued. Here, at Hurst Hill, a sharp anticline brings up the Wen- lock limestones with some overlying calcareous shales 1,000 feet thick and the fossil contents indicate an horizon equivalent to the Lower Ludlow Shales. To these succeeds a bed of limestone 25 feet thick, locally known as the Sedgley Limestone. It is not so pure as the Wen- lock Limestone, and burns into a greyish variety of lime locally dis- tinguished as ' black lime,' that made from the Wenlock Limestone being termed ' white lime.' The commonest fossil is Pentamerus knightii, which stamps it at once as the equivalent of the Aymestry Limestone of Shropshire. Upper Ludlow Shales. Whenever present in full sequence the Silurian deposits indicate a piling up of sediments on an oscillating sea floor until, towards the summit, the accumulations, assisted by gentle uprisings, gradually approached the surface of the sea. The commence- ment only of these conditions is met with in Staffordshire, and this in the Sedgley area alone, where a mere fragment of the lower portion of the Upper Ludlow Shales has been preserved in the centre of a syncline under a capping of Coal-measure sandstone, which has prevented its destruction by denudation. In sinking the Manor Pits near Hales- owen, it is stated that somewhat higher beds containing fossils of the Passage beds into the Old Red Sandstone were entered beneath the Coal- measures, but nowhere has any undoubted Old Red Sandstone been met with, and the formation next succeeding is separated by a great interval of time from the highest Silurian strata exposed on Sedgley Beacon.