The Carboniferous Limestone of the Castleton-Bradwell area, North Derbyshire

Abstract

I. Introduction The area included in the investigation forms a limestone plateau north of the line Perryfoot-Great Hucklow, generally about 1200–1400 feet above sea-level with broad valleys down to 900 feet and hills up to 1500 feet. The west side is formed by the broad valley running south from Windy Knoll; the northern edge runs along the steep slopes from Treak Cliff, behind Castleton to Bradwell; eastwards the area is confined by the valley running south from Bradwell to Hucklow. On these three sides the limestone is bounded by Edale Shales. On the south the area is bounded naturally by the broad depression in the limestone known as Perrydale. The northern edge of the limestone massif is incised by four narrow gorges: beginning on the west, the Winnats, Cavedale, Pindale, and Bradwell Dale. These display the most important profiles. Between the dales the limestone is exposed on the uplands but good continuous sections are rare, although the large quarries opened between Bradwell and Pindale help considerably in the interpretation of the structure and succession. Mining along the numerous lead veins has also exposed the limestone, but these sections are often disappointing owing to the presence of gangue minerals covering the surface of the veins or joints. The Castleton area has long been famous for its fossils, especially the brachiopod limestones of Treak Cliff and the Winnats, but, although frequently mentioned, the limestone has never been described in detail. The Geological Survey memoir on North Derbyshire (Green 1887) did not describe