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Knockan Crag

Ross-Shire & Sutherland border, Scotland

""Spectacular Scenery

The Assynt area in the Northern Highlands is an area that has posed controversy since the early days of James Nicol (1810 – 1879) and Sir Roderick Murchison.


Geologically, the area has undergone complex structural deformation and it was these complexities that were the cause of the problems. It was not until Benjamin Peach and John Horne toured the area that the area’s structural evolution was first interpreted properly.

Knockan Crag was one of the sites where Peach and Horne first understood the nature of thrust tectonics. Here rocks from the Moine Supergroup have been thrust on top of younger Cambrian rocks. Their understanding of this led to crucial, early developments in the field of structural geology.

Knockan CragThe Moine Thrust Zone consists of a series of easterly dipping thrusts that separate the Moine rocks of the Northwest Highlands from the predominantly Lewisian rocks of the Hebridean Craton. The Moine Thrust itself is the oldest and highest of these thrusts and runs from Loch Eriboll on the north coast, SSE along the west coast of the Northern Highlands, before continuing along the southeast coast of the Isle of Skye and the west coast of the Isle of Mull.

Ascending Knockan Crag, Cambrian rocks are found overlain by the older Moine rocks. The Cambrian rocks consist of Pipe Rock, Fucoid Beds, Salterella Grits and Durness limestone – all in stratigraphic sequence. Overlying the Durness limestone are the dark schists of the Moine. These rocks are Precambrian in age.

Knockan Visitor Centre

At the thrust plane, the Durness limestone shows evidence of crushing, and the Moine rocks have been altered to mylonites. This is perhaps the simplest exposure of the Moine Thrust to be found in the region

Text: Scottish Geology

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Images (top to bottom):

  • Knockan Crag © Rob Butler
  • Assynt Mountains from Knockan © John Bryant
  • The Moine Thrust © W.L.Tarbert (Source Wikimedia Commons) Public Domain
  • Pupils from Kinlochbervie High School enjoy a day of discovery at the Knockan Crag visitor centre. At Knockan Crag Scotland's story of ancient oceans, vast deserts and ice sheets, crashing continents and epic journey from pole to pole is told through poetry, sculpture and interactive exhibitions. (© North West Highlands Geopark)
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