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Amphibolite bodies attributed to the Scourie dyke suite are abundant within the Scourian gneiss complex of the Gairloch district. Several sill-like amphibolite sheets of doubtful affinity occur within the Loch Maree Group; however, these are chemically distinct from the Scourie dykes (see Section 4.9.2) and no bodies that can be identified as Scourie dykes cut the rocks of the LMG.
The dykes weather dark grey to almost black and contrast sharply with the much paler acid gneisses. They are generally sheetlike in form, although many show considerable irregularity of shape. The igneous origin and intrusive relationship of these bodies to the host gneisses can be widely demonstrated, and are particularly clearly displayed in the eastern part of the Tollie area, for example on Creag Mhor Thollaidh, and in the southwestern part of the district, around Loch Braigh Horrisdale. In both these areas, the dykes are grossly discordant to the banding of the host gneisses (see map). However, in the two belts of gneisses adjoining the
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