River Etherow - Geology

Geology

Longdendale is a steep-sided V-shaped valley that is glacial in origin. Longdendale is in the Dark Peak, where a thick blanket of peat overlies the Millstone Grit sandstone, formed on a bed of shale through which flows the Etherow. Directly beneath the upper valley lie areas of Carboniferous Millstone Grit, shales and sandstone. It is on the edge of the Peak District Dome, at the southern edge of the Pennine anticline. The Variscan uplift has caused much faulting and Glossopdale was the product of glacial action in the last glaciation period that exploited the weakened rocks. The steep-sided valleys of the cloughs cause significant erosion and deposition. The layers of sandstone, mudstones and shale in the bedrock act as an aquifer to feed the springs. The valley bottoms have a thin deposit of boulder clay. The brooks are fed by the peaty soils of the moors and are, therefore, acidic (pH5.5–7.0).