5: The Dalradian rocks of Lunga, Luing and Shuna

Abstract

Introduction General description of Guide This guide describes the rocks seen on a west to east traverse across the islands of Lunga, Luing and Shuna (Fig. 1), as well as lateral facies changes recognized in Dalradian metasedimentary rocks along these and several other islands, including Belnahua, Insh Island and Kerrera. The rocks involved form part of the Argyll Group (Middle Dalradian) (Harris & Pitcher 1975) and consist of metasedimentary rocks which have suffered polyphase deformation in lowest greenschist facies. Despite the deformation the primary sedimentary features of these rocks have survived. Because the islands afford unusually good opportunities for a study of Dalradian deposition it is with this aspect of the geology that the guide is mainly concerned. Previous work published on the geology of the islands consists of mapping by the Geological Survey (Peach et al. 1909) with a revision by Bailey (1913, 1917) who established the accepted stratigraphic succession of the South-West Highlands. Because this guide describes numerous relatively isolated islands the practical problems of transport, access and timing of visits are very important. Travel details Permission Both Lunga and Shuna are privately owned and, prior to landing, permission must be sought. For Lunga contact the owner, Major B. Johnson-Ferguson, and for Shuna, the Hon. Edward Gully. The whole of Luing and Torsa are farmed by the Cadzow family and it would be courteous to ask permission of the farm manager, Mr. Mackenzie, at Toberonochy. The other islands have complete freedom of access. Transport Due to the extreme . . .