Vol. 70.] THE BALLACHULISH FOLD XEAR LOCH CRERAX. 323 



4'. Striped Series (where separated). 1 A . ~ , ., 

 4. Pebbly Quartzite. } Appm Q uartzite - 



3 & 2. Appin Limestones (3) and Appin Phyllites (2). 

 1. Cuil Bay Slates. 1 



When they are mapped out in detail, it is found that Groups 2 

 to 6, taken together, have a continuous curving outcrop in the 

 neighbourhood of Loch Creran, and that this outcrop separates an 

 internal area of pelitic Leven Schists from an external area of much 

 more quartzose banded rocks — also Leven Schists, but belonging 

 to a different division of this group. The explanation of this has 

 already been given, and is based upon the reading of sections at 

 Loch Leven, Glen Coe, and Glen Etive, north and east of the 

 district now described. It may be summarized as follows : — 



The schists of this region are disposed in a great recumbent fold — the 

 Ballachulish Fold — of which Groups 2 to 6 are taken as constituting the 

 core — the Ballachulish Core. The pelitic Leven Schists of the interior 

 outcrop overlie the Ballachulish Core, while the banded Leven Schists of the 

 exterior outcrop underlie the same. The absence of a belt of pelitic Leven 

 Schists immediately below the Ballachulish Core, corresponding to that 

 above, is due to the presence of the Ballachulish Slide — a powerful 

 fold-fault at the base of the Ballachulish Core. We must not, however, 

 leave out of account an original difference of facies of the Leven Schists 

 above and below the Ballachulish Core in the Loch Creran district : in the 

 upper structural layer the Leven Schists are divisible into an immensely thick 

 pelitic group, and a comparatively insignificant banded series ; in the lower 

 layer the pelitic group is still evidently thick, but the Banded Series seems 

 to have swollen greatly at its expense, and now, so far at least as outcrop is 

 concerned, is predominant. The banded part of the upper layer, and the pelitic 

 part of the lower layer, it may be mentioned, both lie beyond the limits of the 

 map (PI. XLY). 



Another fact determined on outside evidence is that the Ballachulish Fold 

 gupes towards the north-west, and closes towards the south-east. 



Two phenomena strikingly illustrated by the local evidence 

 are : — 



(i) The complexity of the slides affecting the Ballachulish Core, and the 

 correlated quite exceptional occurrence of more groups towards the close of 

 the fold, south-east of the River Creran, than towards the gape, north-west 

 of the same. 



(ii) The intense secondary refolding of the Ballachulish Fold, and the 

 resultant sinuous outcrop of the Ballachulish Core. 



These two phenomena will now be dealt with a little more in 

 detail. 



1 Groups (1) & (9) do not occur in the Loch Creran district (PI. XLY). 

 but are met with in the wider region included in the index-map (p. 322). 

 The uncertainty in regard to Group 9 does not affect the present district. 

 Mr. Carruthers has given good reason for suspecting that various mica-schists , 

 quartzites, and flags, which I have regarded as repetitions of the Leven 

 Schists, Glen Coe Quartzite, andEilde Flags, respectively, are stratigraphicallv 

 distinct. A resume of Mr. Carruthers's position has been published in the 

 ' Summary of Progress for 1912 ' Mem. Geol. Surv. 1913, p. 52. 



