The Lewisian geology of the area between Loch Shieldaig and Loch Bràigh Horrisdale, Gairloch, Ross-shire

Abstract

The Lewisian rocks between Loch Shieldaig and Loch Bràigh Horrisdale consist mainly of acid gneisses, hornblende schists, metadolerites and pegmatites together with quartzo-felspathic and hornblendic segregation veins, lenses and pods. The structural deformation is shown to have occurred in three phases. The dominant foliation and lineation are the result of deformation during the main phase, the N.W.-S.E. trend of the lithological banding and the present lineation pattern are the result of mid phase deformation, while the open folds, which affect both banding and foliation, are the products of late phase deformation.