The Structure of the SoutJi-West Highlands. 301 



in the collections of Dr. Matley and Dr. Greenly, now in the possession 

 of the Geological Survey of England and Wales. 



My best thanks are due to Mr. T. C. Nicholas, Dr. Matley, and 

 Dr. Greenly for the loan of specimens and to Dr. Flett for permission 

 to studv those in the Collection of the Geological Survey. 



The Structure of the South-West Highlands. 



Two Reports on an Excursion, 27tk August to 2nd September, 



1921. 



Report A . 



By W. B. Wright, B.A., E. M. Anderson, M.A., B.Sc, J. E. 

 RiCHEY, M.C., B.A., and H. H. Read, M.Sc, A.R.C.S. 



T AST summer we spent seven days with Mr. E. B. Bailey 

 -*-* investigating some of the evidence upon which he bases his 

 interpretation of the structure of the South-West Highlands, and 

 we feel that our experience should be at the disposal of others 

 interested in the subject. Mr. Bailey's full account of his theory 

 will shortly appear in the Quarterly Journal of the Geological Society 

 of London, and an abstract has already been printed in the 

 Proceedings of that Society, dated April, 1921. In this abstract, 

 the South-West Highlands are allotted to three great structural 

 divisions in descending order as follows : — ■ 



Loch Awe Nappe. 



Iltay Nappe. 



Ballapjiel Foundation. 

 The two lower of these divisions are claimed as structural com- 

 plexes ; for instance, the Iltay Naj)pe is stated to include two 

 major recumbent folds of which the lower may be seen closing 

 north-westwards in Ben Lui. In addition, it is pointed out that the 

 three great structural divisions are themselves involved in later, 

 or secondary, folds, among which the Loch Awe Syncline is a 

 prominent example. 



It is hoped that this outline of Mr. Bailey's position, supple- 

 mented by data presented in his already published pajoers, Avill 

 enable the reader to follow the main points of our statement as 

 given below. 



1. Inspection of the northern termhiation of the Tayvallich Lava 

 outcrop, south of Tayvallich, and of the Loch Avich Slate outcrop, 

 east of Loch Awe, has satisfied us of the reality of Mr. Bailey's 

 stratigraphical subdivision of the Loch Awe Group. ^ 



2. In spite of small-scale isoclinal folding it is easy to establish 

 a descending structural succession within the Loch Awe Group 

 downwards from the Loch Avich Slates.- 



^ Q.J.G.S., vol. lix, 1913, pp. 291, 303. 

 2 Ibid., pp. 292, 293. 



