The Structure of the South-West Highlands of Scotland

Abstract

I. Introduction. The gradual development of structural interpretation in regard to the South-West Highlands of Scotland has much in common with the long-continued building of some great cathedral. The workers have been many, each with his own individuality, and each influenced by the spirit of his time. In these circumstances, preparatory demolition has been an almost inevitable feature of every attempt at improvement. But one is emboldened to the task by the thought that restoration can be carried out if occasion proves its need: a fairly representative literature enshrines the observations and opinions of the long line of researchers. 1 Statement of the Problem. As a preliminary to discussion, the following dogmatic statement is offered. The schists of the South-West Highlands of Scotland belong to three main structural divisions, which, in descending order, are (fig. 1, p. 84 & Pl. 1):— Loch-Awe Nappe, Iltay Nappe, Ballappel Foundation. The first title is derived from Loch Awe. The second is a hybrid of Islay and Loch Tay. The third is compounded from Ballachulish, Appin, and Loch Eilde. Each great division has its particular stratigraphical facies, although there are certain correspondences which suggest stratigraphical correlations from one to another. The Loch-Awe Nappe is relatively simple in structure. The Iltay Nappe includes two important recumbent folds—the Ben-Lui Fold, a syncline closing towards the north-west, and the Carrick-Castle Fold, an anticline closing towards the south-east (fig. 4, p. 102 & Pl. 1). The Ballappel Foundation is a structural complex, with the Ballachulish and Appin Nappes among