Geology of Durness

Tightly folded folds within Lewisian Gneiss found within one of the several sea-caves at Sangobeg. The pink rocks to either side are pegmatite intrusions, similar to granites but are exceptionally coarse grained and the large pink feldspars give the rock it's distinct pink colour.

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The gneisses belong to the Lewisian Gneiss complex. They are highly folded, metamorphic rocks and are coarse, highly crystalline banded gneisses composed of quartz, feldspar and mica (both biotite and muscovite). They are generally very dark to light grey in colour, although some bands give the rocks a pinkish look from afar. Centimetre thick, discontinuous and differing coloured bands reflect the gneissose texture where the different minerals have been grouped into bands of similar mineralogies. The coarser and shiny, biotite-mica rich bands have therefore formed the darker bands and the quartofeldspathic bands have formed light grey to pink coloured bands depending on the varying redness of the feldspars.