part 2] THE SOUTH-WEST HI&HLANDS OE SCOTLAND. 83 



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.^ 



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 & PI. I) :— 



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 Balla- 

 chulish, Appin, and Loch Eilde. 



Each great division has its particular stratigraphical facies, 

 although there are certain correspondences which suggest strati- 

 graphical correlations from one to another. 



The Loch -A we 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 & PI. I). The Ballappel Foundation is a structural complex, 

 with the Ballachulish and Appin Nappes among its component 

 parts. During the development of these various structures, move- 

 ment took place persistently towards the south-east. 



Little would be known of all the nappes and recumbent folds 

 just mentioned, were they not bent and buckled by what we may 

 term secondary folding. The secondary folds of the South - 

 West Highlands are picked out in fig. 1. They include such 

 conspicuous examples as the Cowal Anticline, Loch- Awe Syncline, 

 Islay Anticline, etc. In regard to a large part of the region, it 

 may be stated that the secondary movements were directed out- 

 wards in both directions from the axis of the Loch- Awe Syncline. 

 The Loch-Skerrols ^ Thrust of Islay belongs to the epoch of 

 secondary movement which developed the Islay Anticline. It is 

 probably a continuation of the Moine Thrust, so well known farther 

 north. 



Two important tracts of the South- West Highlands are not 

 dealt with in this paper : — 



(1) The narrow belt of volcanic and fossiliferous rocks commonly styled 



the Highland Border-Rocks; and 



(2) The foreland of the Loch-Skerrols Thrust, as exposed in Islay and 



Colonsay. 



^ The dated references in the sequel are amplified in the Bibliography, 

 App. I, p. 126. 



^ Scottish localities not shown in PI. I are catalogued in the Locality- 

 Index, App. II, p. 127. 



g2 



