GEOLOGY DERBYSHIRE may be divided into two main portions, each of which is marked by its own peculiarities of geological structure and external configuration. The uplands, which consist of the hill country, forming the southern spur of the Pennine Chain, occupy the greater portion of the county. The lowlands, in the southern part of the county, which border on the hilly district and extend to the valley of the Trent. The scenery of the uplands is very varied. The Mountain Limestone, with its outlines generally smooth, its well rounded grassy slopes, intersected by deep, narrow dales and ravines, presents a marked contrast to the wild moorlands and escarpments of the Millstone Grit series. The gorges of the Dove in Dovedale, of the Wye in Miller's Dale, and of the Derwent at Matlock, are examples of the erosion of narrow valleys in limestone. The dales or gorges, such as Great Rocks Dale, Deep Dale near Buxton, Monk's Dale near Miller's Dale, and the Via Gellia near Cromford, while in many respects similiar to those previously mentioned have in some cases insignificant streams of water flowing down them, whilst in others the valley is perfectly dry, the water having found its way underground. The Derwent, the Wye and the Dove illustrate the influence of different rocks in the erosion of river valleys. The Derwent, after flowing in the broad valley of shale from Darley Dale, suddenly enters the Mountain Limestone which rises across its path, instead of continuing in the shales and skirting the limestone as far as Cromford. The course of the river was determined before the valley of Darley Dale was formed, and the cutting of the gorge in the limestone and the broad valley in the shale proceeded together. The Wye from Buxton to Bakewell runs in a narrow gorge, but in the shales near Haddon pursues a serpentine course in the broad valley which it has excavated in the softer rocks. The Dove, after flowing in the shales near Hartington, enters the limestone near Beresford Hall, pursues a course for several miles through Dovedale, and enters the shales again near Thorpe, where the valley becomes broader and less rugged. In the Gritstone country some valleys run parallel to the strike of the rocks. They often lie between two escarpments of grit which are separated by a bed of shale. The south side of the valley of Ashop Clough is formed of an escarpment of grit resting on a thick bed of
