Arnaboll Thrust

Arnaboll Thrust

The Arnaboll Thrust on the east side of Loch Eriboll is where the term mylonite was first used. Here the much older Lewisian gneisses lie structurally above the light-coloured quartz arenites of the Lower Cambrian Pipe Rock. The mylonites are derived from both units and form a narrow zone only a few metres thick.