Ard Hill
Also within
Condition (NatureScot)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| F1 | Moine | Part Destroyed | — | 2009-08-14 |
Climate exposure
This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.
Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.
Geology & landscape
Landscape processes: Coastal
Description
ARD HILL Ard Hill Site of Special Scientific Interest (SSSI) is situated on the northern shore of Loch Alsh, near Balmacara. This site provides excellent exposures of the Balmacara Thrust, the overlying Balmacara Nappe, and the underlying Kishorn Nappe, within the Moine Thrust Belt. The Moine Thrust is a major fracture in the Earth’s crust, which runs along Scotland’s north-western seaboard from Loch Eriboll on the north coast of Sutherland to the Sleat peninsula. The Thrust is one of the most important features of Highland geology and was formed around 430 million years ago during a mountain-building event known as the ‘Caledonian Orogeny’. The Moine Thrust Belt extends westwards from the Moine Thrust and encompasses a number of other Thrusts. In the Lochalsh area these are the Balmacara Thrust and the Kishorn Thrust. At Ard Hill SSSI, the formation of mylonites (a fine-grained rock formed by the crushing and grinding which can occur under intense shearing pressure) is associated with the development of a large fold structure (the Lochalsh Syncline). Two subsequent fold phases can also be recognised in the mylonites. The final phase of deformation in the area was the formation of the Balmacara Thrust. Torridonian and Lewisian mylonites, of the Kishorn and Balmacara Nappes respectively, are brecciated (broken up) along the Balmacara Thrust, clearly indicating that the thrusting occurred after the mylonite formation. Ard Hill SSSI is one of the key sites in the Moine Thrust Belt which convincingly demonstrates a distinction in time between mylonite formation and thrusting.