North West Highlands Geopark (2016) North West Highlands Geopark Geodiversity Audit and Action Plan 2013–2016
Additional notes: These web pages are sourced from the PDF North West Highlands Geopark Geodiversity Audit and Action Plan 2013–2016
NWHG Ref. 042 — Allt na Cailliche
Location, grid reference and photograph
The site is located close to where the Allt na Cailliche flows into the south-east corner of Loch Ailsh, Grid Ref.
GCR site reference, block, volume and notified feature of SSSI?
GCR Ref. 1229, Caledonian Igneous Block, Vol. 17. Confirmed GCR site, not SSSI notified.
Description and geological significance
The exposure is representative of a suite of quartz-syenite (nordmarkite) sills which occur just above the plane of the Moine Thrust. It demonstrates that emplacement of the sills was controlled and localised by the thrusts themselves and that subsequent deformation and recrystallisation of the nordmarkites was caused by late movements on the thrust plane.
Accessibility
Access to the site is by driving along unsurfaced forestry roads on the north-east side of Glen Oykell, followed by a short walk, in part along and through a heavily vegetated river gorge. There is, therefore, no access for all abilities.
Conservation
Low conservation requirement due to the scale and location of the site.
Visibility and “clarity”
The site is visible within the course of the Allt na Cailliche but is difficult to find and to interpret.
Interpretation and interpretation potential
The site is of very limited interest for the general public.. The site is effectively only of interest to geology students and researchers.
Key references
PARSONS, I. 1999. Late Ordovician to mid-Silutian alkaline intrusions of the North-west Highlands of Scotland. In Stephenson, D., Bevins, R. E., Milward, D., Highton, A. J., Parsons, I., Stone, P. & Wadsworth, W. J. (eds) Caledonian Igneous rocks of Great Britain. Geological Conservation Review Series, 17, Chapman & Hall, 345–393. (site description page 391).