Vol. 70.] BALLACHULISH FOLD XEAR LOCH CEERAX. 325 



•of what is now, for convenience, shown as a single limestone out- 

 crop. As a result, the mapping on the two sides of the fault would 

 be brought into closer agreement than at present. A revision, 

 effected on these lines, would probably also indicate a less dentate 

 outcrop for the slides, but the difference would merely involve 

 changes of local import. The limestone (calc-silicate-hornfels, 

 with some dark marble) in the eastern outcrops, exposed on the 

 slopes north of Allt Buidhe, certainly belongs wholly to the 

 Ballachulish Group. 



After being obliterated for a little by the Cruachan Granite, the 

 Ballachulish Slide reappears as a single structure. It swings round 

 sharply to the west for a space, and its course is somewhat ill 

 defined — owing to the difficulty of determining an exact line sepa- 

 rating the contact-altered Striped Series (4') from the Banded 

 Series (7'). The difficulty is not nearly so marked, however, as 

 would have been the case nearer Loch Creran, for the Leven Schists 

 at this point, although banded with quartzose ribs, are in large 

 measure pelitic grey mica-schists, already indicating an approach 

 to the facies of the group as developed in the structural layer 

 overlying the Ballachulish Core. Beyond this westward turn, the 

 Ballachulish Slide is very easily traced, as it separates Ballachulish 

 Slates (5) from the comparatively pelitic Banded Series (7'). For 

 a short distance, a thickness of some 40 feet of calc-silicate-hornfels, 

 representing part of the Ballachulish Limestone (6), separates 

 the two. 



Before reaching the granite margin, on the slopes of Glen Ure, 

 the Ballachulish Slates fail, and the Ballachulish Limestone of the 

 upper limb of the great fold comes directly into contact with the 

 Banded Series on the south. 



A point of very considerable importance is the occurrence of pebbly 

 Glen Coe Quartzite (8) in association with the banded Leven 

 Schists (7') which occur here between the Ballachulish Slide and 

 the Cruachan Granite. In the typical region the Glen Coe 

 Quartzite is fine-grained ; in the exposures now considered it is 

 coarsely pebbly, with large grains of quartz and felspar. In this 

 feature it resembles the Appin Quartzite (4) ; but. even so, there 

 can be no possibility of mistaking the two rocks, for the Glen Coe 

 Quartzite is interbanded with grey semipelitic material, towards 

 its margins especially, and is linked inseparably with the banded 

 Leven Schists — nor is it a case of mere mechanical intermingling, 

 for many of the semipelitic beds cany quartz- and felspar-pebbles. 

 It is interesting to recall that in Glen Strae, on the other side of the 

 Cruachan Granite, a similar pebbly quartzite, in what is believed 

 to be the same structural position with relation to the Ballachulish 

 Slide, has already been assigned to the Glen Coe horizon. 1 



Only one other slide need be mentioned specially in this summary. 

 It has been known for some years to extend about 5 miles north 



[■ » E. B. Bailey & M. Macgreg-or ' The Glen Orchy Anticline ' Q. J. G. S. 

 vol. lxviii (1912) p. 172. 



