108 ME. E. B. BAILEY ON THE STRUCTUEE OF [vol. Ixxviii, 



The inter-nappe correlations suggested above are treated in this 

 part as an end in themselves. They are not emploj^ed as links in 

 the chain of evidence supporting the general structural interpreta- 

 tion, except in so far as they add somewhat to the strength of the 

 conclusion that the Ballappel succession is correctly stated in 

 descending order of age on p. 104. I may add, perhaps, that a 

 visit to Blair Atholl (Perthshire) in 1920 impressed me very 

 strongly with the value of the correlations here suggested. One 

 cannot well question that the Perthshire Quartzite as exposed in 

 Ben-y-Glo belongs to the Islay Quartzite, and yet its associates 

 remind me irresistibly of Appin Limestone and Phyllites (with a 

 weak development of Portaskaig Conglomerate) followed by Cuil- 

 Bay Slates and Islay Limestone. In the Ballachulish district the 

 sequence ends with Cuil-Bay Slates — unless the tantalizingl}^ 

 isolated Lismore Limestone, restricted to island occurrences, be 

 distinct from the Ballachulish Limestone with which it has been 

 hitherto correlated. ^ 



III. Ceitical Discussion of the District beaching feom 

 Aedmucknish to Ben Lui. 



Having now clambered somewhat laboriously from the summit 

 of the Loch- Awe Nappe across the Iltay Nappe right down to 

 the Ballappel Foundation, the reader is in a position to turn 

 round, as it were, and view with comprehension the outstanding 

 features of the structural succession considered as a whole. Near 

 Dalmally, the outcrops of the Loch-Awe G-roup and Eilde Flags 

 approach unusually close, while whole assemblages, well known to 

 intervene between these two farther north-west or south-east, as 

 the case may be, are here entirely absent (fig. 5, p. 109). It is 

 miy present task to indicate how some of these discrepancies are 

 attributable to recumbent folding ^ and others to thrusting, and 

 in so doing to bring my long description to a close. Unfortunatelj^, 

 it will be impossible to avoid the introduction of considerable local 

 detail, for much of the reasoning is based on hitherto-unrecorded 

 field-observations. 



Appin and Ballachulish Folds. 



Since the Appin and Ballachulish Folds have been very fully 

 described (1910 «; 1912 & ; 1914; 1916), the following dogmatic 

 statements regarding thera must suffice : — 



(1) The two folds close quite clearly south-eastwards. 



(2) The groups enumerated in explanation of A & B, fig. 5, and with 

 them the Ballachulish Limestone, do not continue far underground in the core 

 of the Appin Fold. I once thought that a limestone exposed near Loch 

 Dochard (12 miles south-east of Ballachulish) was probably the Ballachulish 

 Limestone enclosed in the Appin Fold ; but I now regard it as occupying a 

 lower structural level (p. 94). 



^ It is coloured as Ballachulish Limestone in PI. I. 

 ^ See also 1922, Report A, par. 6. 



