Glendrian Caves lie just under a kilometre to the east of the abandoned village of Plocaig on Ardnamurchan's spectacular north coast. The main cave, shown, is a dark, angled cleft which enters the rock to some depth, and is only accessible as the tide retreats.
The Diary visited the caves recently with local geologist and businessman Rob Gill, who runs Geosec Slides from his house in Achnaha - and a fascinating expedition it was.
Some of the structures are difficult to interpret, like the large lump of layered rock which runs across the middle of this picture - it's about three metres across and up to a metre thick. It looks like a finely-layered volcanic ash deposit, but it seems out-of-place in a mess of rock which tumbled down a steep slope.
A map of the area is available here. The caves are some distance from the nearest road, and are difficult to access unless you're well equipped. The easiest approach is from Achnaha, though it can be hard going, particularly after heavy rain.
Many thanks to Rob Gill for an enjoyable and instructive experience.
Geosec Slides' website is here.