Drumadoon cliff on the Isle of Arran is a Palaeogene quartz-feldspar-porphyry sill displaying massive columnar jointing. On the neighbouring shore there are many E-W trending dykes, members of the Palaeogene dyke swarm.
The Drumadoon sill, displaying columnar jointing. (Photo: W. Gray)
An excursion itinerary for this site, prepared by J.G. MacDonald in 2015, can be found here.