Beinn a' Chapuill

Also within

Ross and Cromarty County Knoydart Scenic Area 18. Kinlochhourn - Knoydart - Morar Wild Land Area

Condition (NatureScot)

Description

BEINN A’ CHAPUILL Beinn a’ Chapuill Site of Special Scientific Interest (SSSI) lies near the centre of the Glenelg peninsula, from where it overlooks the Sound of Sleat to the west and Loch Hourn to the south. Exposures of the Glenelg Inlier are found here. The Glenelg Inlier is an exposed area of ancient rocks called Lewisian gneisses, surrounded by much younger metamorphic rocks belonging to the Moine Supergroup, which are the rocks that underlie much of the Northern Highlands. A major zone of shearing runs roughly north-south through the Glenelg Inlier and because the gneisses on either side exhibit different characteristics they are termed the Eastern and Western Units. This SSSI contains rocks of the Eastern Unit which clearly demonstrate a large (kilometre) scale refolded fold. This refolded fold is one of the clearest and best-documented examples in Britain of this feature at such a scale. The site is also of international importance for its role in the development of studies of structural geology throughout the world. The rocks of the Beinn a’ Chapuill SSSI illustrate where the structure of the Beinn a’ Chapuill Fold, (affecting Lewisian and Moine rocks) has subsequently been folded by the later Beinn a’ Chaoinich – Beinn Mhialairidh Fold. There is also abundant evidence that prior to these two phases of large-scale folding, the Lewisian and overlying Moine rocks were folded intricately together, probably resulting in thin layers of the two rock types becoming interleaved. The clear demonstration of three episodes of folding and their effects makes the site important for understanding the deformation history of the Moine and Lewisian rocks, and therefore in aiding an understanding of the structural geology of the northwest Highlands.