NWHG Ref. 021 — An Fharaid Mhor — Clachtoll

Location, grid reference and photograph

The site encompasses the peninsula of An Fharaid Mhor, Achmelvich Bay and northwards to Clachtoll, on the west coast of Assynt, Grid Ref. [NC 038 270][NC 069 245].

(Figure 23) Rugged coastline north of Achmelvich. BGS Photo P 513583 — M Krabbendam.

(Figure 24) Structures in Lewisian gneiss, beach north-west of Achmelvich. BGS Photo P513591 — M Krabbendam.

GCR site reference, block, volume and notified feature of SSSI?

GCR Ref. 2444, Lewisian Block, Vol. 34. Confirmed GCR site, not SSSI notified feature.

Description and geological significance

The site is of international importance as it is the type locality for the Inverian event which occurred in the mainland Lewisian Gneiss Complex. It also encompasses part of the 1.5 km-wide Canisp Shear Zone, an exceptional example of a shear zone initiated during the Inverian event and subsequently partly reactivated during the Laxfordian. Many structures, although difficult to interpret, are visually attractive and occur in a scenic coastal area.

Accessibility

The area is accessed via the B 869 Lochinver-Drumbeg road but requires a considerable amount of walking over rough and remote terrain in order to reach most of the exposures. There is therefore no all abilities access.

Conservation

Low conservation requirement due to the scale and location of the area.

Visibility and “clarity”

Key exposures are not visible from the nearest road. Some exposures are visible on popular beaches.

Interpretation and interpretation potential

The site is of interest to geological specialists rather than the general public. The site features as a walk in the “Exploring the landscape of Assynt” guide book. There is no on-site interpretation which would be inappropriate in this situation. Nonetheless, the site area could be developed as a teaching resource for universities and students and it should certainly be included in a future Geopark guide. Guided walks would also be likely to be successful.

Key references

ATTFIELD, P. 1987. The structural history of the Canisp Shear Zone. In Park, R. G. & Tarney, J. (eds) Evolution of the Lewisian and comparable Precambrian high- grade terrains. Geological Society Special Publication 27, 165–173.

PARK, R.G. 2009. An Fharaid Mhor to Clachtoll. In Mendum, J. R., Barber, A. J., Butler, R. W. H., Flinn, D., Goodenough, K. M., Krabbendam, M., Park, R. G. & Stewart, A. D. (eds) Lewisian, Torridonian and Moine rocks of Scotland. Geological Conservation Review Series, 34, Joint Nature Conservation Committee, Peterborough, 147–151.