The stratigraphy and structure of part of the Kintail district of southern Ross-shire : Its relation to the Northern Highlands

Abstract

Summary The portion of southern Ross-shire dealt with in this paper lies between the two recently redescribed districts of Fannich Forest (Sutton & Watson 1954) on the north, and Morar, Inverness-shire (Kennedy 1955), on the south. This paper provides the first detailed geological survey of the area. The district is composed essentially of crystalline schists and gneisses of the Lewisian Gneiss and Moine Series disposed in north-easterly and north-north-easterly trending major isoclinal folds. Within the most important of these, the Sgùrr an Airgid syncline, the following structural succession has been established :— The upper element is regarded as composed of exotic representatives of the lower element repeated at higher levels by thrusting ; in view of the disposition of this element as a structural outlier it is termed the Kintail klippe. The question of a root-zone is discussed. The major post-Moinian structural events in southern Ross-shire have been recognized as thrusting and the emplacement of the Kintail nappe, folding along NE.—SW. (Caledonide) axes and the development of WNW.—ESE. trending " crossfolds." These phases were followed by post-metamorphic faulting as exemplified in the Strathconon fault plexus. The regional implications of the now map area are discussed.