View at Bennan Head, south coast of Arran, Buteshire


Distant views of the Bennan Head composite dolerite - quartz porphyry sill intrusive in Triassic sandstone. Dolerite dykes on foreshore and raised beach in foreground.

The upper part of the cliff is formed of quartz porphyry, with dolerite near the base of the sill, which becomes lower westwards and reaches sea level near the point. At the right edge of the photo, horizontally-bedded sandstone is visible under the dolerite. North-south dolerite dykes occur on the foreshore. Note the apparent absence of dykes cutting the sill, which must post-date the dykes. The raised beach at the foot of the cliffs was formed during a period of high sea level shortly after the end of the latest glaciation.

SCRAN ID: 000-000-146-236-C; British Geological Survey