Page:VCH Staffordshire 1.djvu/37

 GEOLOGY were of brief duration and of sparse recurrence, for the series consists essentially of clays, shales, muds and sandstones of a united thickness of many hundreds of feet. Occasionally the quantity of vegetable matter floated down was in excess of any other material, and a mass of decaying vegetable debris accumulated, to be ultimately converted into a seam of coal, or it may be the carbonaceous matter collected in swamps lying at or near sea level. The Pendleside Series occurs in two areas to the east and west of Leek, being brought into this position by two major folds separated by the trough enclosing the Coal-measures of the Cheadle and Shaffalong Coal- fields with their enveloping Millstone Grits. The major folds are made up of minor convolutions, frequently of great complexity, of which a striking illustration is afforded by a section in Badgers Clough near Pye- Clough. The extensive quarries on the anticline of Gun Hill, west of Meerbrook, also forcibly illustrate, in the bent and shattered Pendleside grits and shales, the violent nature of the disturbances and the amount of compression the strata have undergone ; nor is this to be wondered at, seeing that these sections lie well within the influence of the Great Pennine uplift the dominant structural feature of mid-England. With the exception of deep dingles or gorges like those of the Dane Valley system and Churnet Valley the scenery is tame, consisting for the most part of open grassy moorland. This is due chiefly to the preponderance of soft shales, but also in part to the frequent low inclination of the strata. Whenever ridges such as Catsedge, Gun Hill and Morridge relieve this monotony they are found to be composed of sandstone or grit, of which the harder and more siliceous varieties are known as Crowstones, when they are extensively quarried for rough road metal. Coal smuts, thin seams of coal with fireclays, occasionally underlie these grits, and were formerly worked to a limited extent. Fossils are comparatively rare and poorly preserved. They occur in certain restricted bands in the shales, but are more abundant and better preserved in some thin layers and nodules (bullions) of dark earthy lime- stones clearly exposed in the banks of the Dane south of Wincle. They include several species of Gonia fifes (Glyphioceras), Posidonomya Becheri, Pterinopecten papyraceus, Posidoniella /avis, fossils Messrs. Hind and Howe find characterizing a similar set of strata above the Mountain Limestone in adjacent counties, especially on Pendle Hill (Lancashire), from which the series derives its name. The river system which transported the sediments of the Pendleside Series is considered by Dr. Hind to have flowed from the east and north- east. He observes the series to be thickest over Lancashire, where the succeeding Millstone Grits are also at their maximum development, while from this centre the beds thin out in all directions ; thus North Staffordshire lay towards the southern margin, South Staffordshire wholly beyond it. These strata have for long been regarded as the southern equivalent of the thick bands of white limestone and interbedded shales of Yoredale,