Landslip at Mam Tor, Derbyshire

This road was closed in the 1970s after repeated landslips, following heavy rain. Sandstones higher up Mam Tor overlie weak mudctones (beneath the road). Rain water seeps through the sandstones into the mudstones, which become soft clay, allowing the slope to settle downhill. Geologists have found evidence showing that this slip has been moving for over 3000 years!