Page:VCH Staffordshire 1.djvu/35

GEOLOGY was marked by minor earth movements temporarily raising one area and depressing a closely contiguous one. Therefore, in the important search for coal underneath the red rocks, it will long remain uncertain what particular member of the Carboniferous System will be encountered or what its thickness will be. Differences in the distribution of the fossils have been taken to mark out the Carboniferous System into an Upper and a Lower portion, but authorities are at variance as to where the divisional line should be drawn. The plants and fishes indicate a change at the top of the so-called Yoredales (Pendleside Series) of Staffordshire ; the mollusca on the other hand show no such differences, but many of the marine forms con- tinue from the base of the Pendleside Series to high up in the Coal- measures. In a short sketch however it is out of place to enter into a discussion of this vexed question ; whatever floral and faunal changes may ultimately be found to differentiate the various stages, stratigraphi- cally, as Ramsay always contended, the Carboniferous System can be regarded as a unit. CARBONIFEROUS OR MOUNTAIN LIMESTONE The celebrated scenery of Dovedale and the beautiful valley of the Manifold owe their charms to the rocks of this important sub-division. Excavated into deep gorges and pinnacles of fantastic shapes, enhanced by the soft verdure of peculiar vividness and the delicacy of outline of numerous limestone-loving plants, threaded with caves and mysterious underground water channels, the Carboniferous Limestone country ever exerts a strong impression on the mind. The Carboniferous Limestone, which, as previously mentioned, only occurs in the north of the county, consists of an undivided mass of pale grey, white or blue limestone of great but undetermined thickness. The quality of the rock varies from place to place ; that at Caldon Low in the Weaver Hills is of exceptional purity, and thousands of tons are annually quarried for use as a flux in the iron furnaces of Staffordshire and for the production of alkalies and lime for various purposes. The pipes and hollows traversing the rocks have also yielded large quantities of copper and lead, the famous mines at Ecton being considered, toward rhe com- mencement of the eighteenth century, to be the richest copper mines in Europe. The outcrop of limestone in the Weaver Hills and the Manifold Valley forms a southerly extension of the large massif of the Carboniferous Lime- stone of Derbyshire, and similarily owes its existence to a strong anti- clinal uplift bringing it to the surface from under the denuded cover of the shales and grits of the Pendleside Series. The convolutions visible in the Staffordshire lobe of the Derbyshire limestone west of the Dove are doubtless continued, underneath the folded Pendleside strata, to the west of the main limestone outcrop in the Weaver Hills. This is shown to be the case by the small mass of limestone which comes to the surface 7