Mam Tor hill fort

Mam Tor is a hill near Castleton in the High Peak of Derbyshire, England. Its name means "mother hill", so called because frequent landslips on its eastern face have resulted in a multitude of 'mini-hills' beneath it. These landslips, which are caused by unstable lower layers of shale, also give the hill its alternative name of Shivering Mountain. In 1979 the continual battle to maintain the A625 road (Sheffield to Chapel en le Frith) on the crumbling eastern side of the hill was lost when the road officially closed as a through-route. At the base of the Tor and nearby are four show caves: Blue John Cavern, Speedwell Cavern, Peak Cavern and Treak Cliff Cavern where lead, Blue John, fluorspar and other minerals were once mined.