The majority of the rocks at Dùn Coillich are Dalradian Schists but there are also significant outcrops of Dalradian Limestone: an ancient hard Limestone which places host to lime loving flowers such as rock rose, globe flower, wild strawberry and thyme.
The Schiehallion Boulder bed is found in various areas. It has a fascinating provenance - it is thought to have originated in Greenland where ice eroded boulders and pebbles of pink granite before carrying them in icebergs to Scotland. When the ice melted, the granite rained down onto the sea's floor and here the pebbles and boulders were then consolidated in the sediment to form the Boulder bed. It is a famous rock that outcrops in patches to the southwest as far as Port Askaig on the island of Islay.
» Read the Tayside Geodiversity Action Plan.