Page:VCH Herefordshire 1.djvu/46

 A HISTORY OF HEREFORDSHIRE may be classed under two heads according as their alignment is (i) north and south (Malvernian direction), or north-west and south-east (Woolhope or Charnian), or (2) at right angles to these, were produced. In the case of the folds of both sets, so intense was the crust-pressure, that frequently the anticlines were overfolded in the opposite direction to that from which the force acted. Professor Groom sees no reason for supposing that the differently orientated anticlines were produced otherwise than contemporaneously ; but this appears to be a matter that requires more investigation. Where an axis of one set of folds crossed the corresponding axis of the other the stress found reUef in causing the rocks to assume a dome-like form. Mr. T. Mellard Reade, speaking of the genesis of the Woolhope Dome, recognized in the disposition of its rocks the expression of peripheral stress. It is easy to see that crust-pressure — interpreted as forces acting from southerly and easterly directions — would induce such a stress. The beautiful scenery of this county is mainly due to the crust-pressures which effected a flexuring of its rocks near the close of Carboniferous times. If a district were composed of one kind of rock only its configuration would be tame in the extreme, because the essentials for what has been aptly described as ' differential denudation ' to produce a diversified scenery would be wanting. The more diverse the rocky composition, the more diverse will be the scenery. Crust-pressures have caused the elevation of the Malvern Hills, and the differential action of denudation upon the hard Archaean rocks amid the softer beds of sedimentary origin has produced that serrated range, which, in the words of Lord Avebury, presents ' one of the most striking features in the interior of the kingdom.' The rock-systems which are represented in part or whole older than the Old Red Sandstone, are the Silurian, Cambrian, and Pre-Cambrian or Archaean ; those which are younger, the Carboniferous, Permian, Triassic, and Pleistocene (see Table of Strata). Only very small areas are occupied by rocks younger than the Old Red, and it is very doubtful how far these beds originally extended over the county. Certainly, since the latest ' solid ' rocks were laid down over the county there has elapsed a vast period of time during which denudation has been sculpturing the surface of the shire. The River Wye, whose history is more interesting than that of perhaps any other British river, has played no small part in outlining the present configuration. As will be shown later this river is made up of portions of several rivers once distinct. Directed in the first place by the lie of the rocks it has become almost independent thereof by its continued growth, although it has lost as well as gained tributaries. By the network of streams thus evolved has been developed that undulating expanse which is the glory of Herefordshire scenery. The ' superficial ' deposits, consisting of sand, gravel, and clay, have been laid down in patches of various thickness and extent upon this much sculptured surface. During the later phases of the development of the Wye System, they have been somewhat redistributed in places or cut through by the streams and rivers. Bordering these are the most recent rocks in the form of mud, known as ' Alluvium,' and gravel, the level stretches which they make furnishing some of the richest meadow-land in the county.