With regards to Mam Tor, and its rotational landslide...
It is known locally as "shivering mountain", due to continuous slipping of the shale slopes.
Before local government reorganisation, Chapel-en-le-Frith Rural District Council kept a road roller and workman's van parked in a layby there permanently, so that any slip could fairly quickly be repaired by rolling in yet more tarmacadam.
However, responsibility for the A625 passed to Derbyshire County Council in the mid 1970s, and the "experts" in Matlock could not see the sense of keeping valuable assets in such a location, so they were taken elsewhere. Needless to say, next time there was a significant slip, by the time they had got there, it had moved again, so they gave up on it.