The sharply cut cavern seen ahead is the entrance to a long-abandoned silver mine in the cliffs to the north of Combe Martin. There are the remains of several silver mines in the area as it was extensively extracted about 200 years ago - see http://www.johnhmoore.co.uk/hele/mining.htm for much more information on these mines.
Uploaded to Geograph by Rob Farrow on 28 August 2014
Photo © Rob Farrow, 28 August 2014. Licensed for reuse under this Creative Commons licence