Page:VCH Staffordshire 1.djvu/39

 GEOLOGY have exerted a powerful influence on the ancient inhabitants, appearing to them as something above the common and therefore fit burial places for their chiefs. Many of the stream-cut gorges are strikingly deep and gloomy ; while elsewhere the rocks have been opened out into curious chasms, such as the impressive cleft of Ludchurch 100 yards long, 30 to 40 feet deep, and 6 to i o feet wide south of the Castle Cliff Rocks. The Millstone Grits are arranged in lesser or greater synclinal folds completely or partially surrounding the coalfields; frequently, as in the small elongated trough of Goldsitch Moss with perfect symmetry. Denudation has removed vast masses of material, thus severing the outcrops and forming detached areas, of which the outlier of the Third or Roaches Grit on the summit of Sheen Hill is the most remote. Seams of coal which are rare in the Pendleside Series become of greater frequency and are usually present a few feet above or lying directly on the grit bands. The most persistent is a seam above the Third Grit, which was formerly worked to a considerable extent in the Roaches and Ipstones areas. Another seam, known as the Feather Edge Coal, lying above the First Grit, also proved to be workable around parts of the Goldsitch Moss Coalfield, though the seam should more properly be included in the Coal-measures. The commercial value of the sub-division however mainly consists in the fairly good quality of the building stones afforded by the First and Third Grits, both of them, but especially the latter, being extensively quarried. The fossils of the ' grits ' consist of the remains of plants Ca/amifes, Lepidodendron. Plant remains are also met with in the shales, but the most interesting fossils are the marine organisms Ptennopecten papy- raceus, Posidoniella /&vis, Goniatites which occur in abundance in certain dark bands of impure limestone lying in muddy shales between the First and Third Grits, of which the banks of the Trent to the east of Knypers- ley Reservoir afford an excellent section. COAL MEASURES The detritus-bearing currents now swift, now gentle which de- posited the grits and shales of the Pendleside Series and Millstone Grits continued to carry their burden seaward long after the First Grit was laid down. The pauses in sedimentation however became more prolonged, the sea was frequently excluded, and the floor, owing to constant deposition aided by local elevation, was even raised above sea-level. The lower portion of the Coal-measure formation, with its great thicknesses of shales, clays, sandstone and intercalated coal seams, ironstones and marine bands, demands some such varied conditions of origin. During the later stages of the period the pauses became brief and a large body of sediment was deposited, but now under new conditions. A land-locked area appears to have been formed upon whose continuously sinking floor mainly red sediments thickly accumulated. The end of the story however is not known ; the record is lost or buried deep under the overlying Triassic rocks with their history of a new order of events. ii