The combined effects of geology and geomorphological development at Mam Tor in Derbyshire have produced a series of large and impressive landslips. In 1977 the A625 Castleton to Whaley Bridge road, which crosses one of these slips, was finally closed after further movement displaced parts of the carriageway, and the programme of repair and maintenance which had been undertaken for more than seventy years was ended.
Mam Tor is part of an unstable ridge of Carboniferous, Namurian shales capped by Mam Tor sandstones and there are three major landslips close to the hill. The photograph shows the nature and extent of the two landslips on the northern side of the ridge. Where there is no vegetation a blue-grey colour is recorded and vegetation is represented by red. On this false colour infra-red image there is a notable record of differential development in vegetation, highlighting areas of ground water seepage and issues. Differences in vegetation density and health are indicated by intensity of colour, and bright red areas correspond to high levels of vegetation development at, and adjacent to, surface water. Flows from the sandstones in the ridge and the landslipped materials are both indicated. Water issues from the sandstone units in the back scar of the Cold Side landslip and is re-distributed as surface run-off and flows through the landslip mass (Fig. 1). The latter re-appears from issues near the toe. Small-scale seepage can be traced along the side of the ridge; in the middle distance the prominent scar of
- © The Geological Society 1984