Up until 1979, this was the main road (the A625) between Castleton and Chapel-en-le-Frith, that wound it’s way across the south eastern flank of Mam Tor. It was eventually abandoned in that year after a history of landslips. From the image you can clearly see the landslip is still active.
Mam Tor is locally known as ‘the shivering mountain’ because of this landslip. It makes for an interesting image in the low morning sun.