Page:VCH Staffordshire 1.djvu/36

 A HISTORY OF STAFFORDSHIRE at Mixon on the crest of a long oval-shaped dome that is bent into a large number of lesser anticlines and synclines, and threaded with mineral lodes containing ores of copper and lead. The top beds are also brought up on another sharp fold in an old quarry near Congleton Edge, close to the county border, west of Biddulph. In this section the highest thin bands of limestone are intercalated with layers of tuffs, fragments of lava and ashy fossiliferous limestone, thus denoting the presence of volcanic action during the deposition of the strata. 1 Such evidences of igneous or vol- canic activity during or closely subsequent to the deposition of the limestone are abundant in Derbyshire, but do not actually occur within the county. A curious bed made up of rolled shells and fragments of waterworn limestone has been traced by Dr. Wheelton Hind in the valley of the Manifold, from Apes Tor to Ecton Bridge and Warslow. It occurs at or near the summit of the limestone, a position it occupies in several places in Derbyshire, notably near Castleton. The Carboniferous Limestone abounds in fossils, including genera and species of corals, brachiopods, lamellibranchs, gasteropods, crustaceans and cephalopods, and other invertebrates. The prolific trilobite fauna of the Silurian and Devonian seas is however represented by only three genera Bracbymetopus, Griffitbides and Pbillipsia forms distinct from those of the preceding formations. Fish remains are not abundant within the Staffordshire area, but numerous specimens have been obtained at Park Hill in Derbyshire, just across the county border, including types with pavement teeth such as would be adapted for grinding and crushing corals. Attempts have been made, but with little success, to distinguish one part of the massive limestone from another by means of the fossils. Dr. Wheelton Hind regards the limestone as one big zone, of which Productus giganteus, P. cora, Ghonetes papilionacea, Amplexus coralloides constitute the zonal forms, and have a general dis- tribution throughout the deposits of the period. PENDLESIDE SERIES The clear waters of the limestone seas became ultimately charged with silts and muds brought down by a large river which spread its deposits not only over North Staffordshire but also over a wide area in mid-England, and which possibly reached the Isle of Man. 2 With this change of conditions the varied marine fauna of the Car- boniferous Limestone seas vanished and was replaced by a few mud-loving molluscs, some of which are found attached to pieces of timber floated out into the turbid waters. Muds ceased at times to be borne seaward, enabling a marine fauna to establish itself. These periods of compara- tively clear water, of which the fauna is abundantly preserved on Congleton Edge in the strata exposed in a quarry to the east of the limestone inlier, 1 W. Gibson and W. Hind, 'On Agglomerates and Tuffs in the Carboniferous Limestone Series of Congleton Edge,' Quart. Journ. Geol. Sac. p. 548 (1899). J W. Hind, Stuart. Journ. Geol. Soc. Ivii. 374 (i9 O1 )- 8