320 ME. E. E. EAILEY ON THE [Dec. 1914, 



of the district here described to Sgorr a' Choise, near Ballachulish, 

 and on this account may he termed the Sgorr a' Choise Slide. 

 In its northern extension it almost constantly lies some little way 

 within the Ballachulish Core ; hut, for a short distance east of Allt 

 Coire Mulrooney, it constitutes the actual boundary of the core 

 bringing Ballachulish Slates (5) into contact with Leven Schists (7). 

 South of Allt Coire Mulrooney, the Ballachulish Slates disappear on 

 the north-west side of the slide, while the pale highly-inipure portion 

 of the Ballachulish Limestone is prominently developed on the 

 south-east side. For a distance of over a mile south-west from 

 Allt Coire Mulrooney, greatly thinned-out representatives of the 

 Appin Quartzite (4) and Limestone (3) persist on the north-west 

 side of the Sgorr a' Choise Slide. The limestone is well exposed 

 in Easan Diblidh, and in the burn at Fasnacloich ; the quartzite 

 is seen both here and in intermediate exposures. South-east of 

 the .Fasnacloich burn, the quartzite and limestone both fail, but 

 a belt of Appin Phyllites (2) still continues, until it tapers out, . 

 half a mile farther on, in the heart of Ballachulish Slates (5). At 

 this point the Sgorr a' Choise Slide and the upper branch of the 

 Ballachulish Slide run together, and are no longer traceable. 



A glance at the map will show that the Ballachulish and the 

 Sgorr a' Choise Slides are complemeirtaiy. Both cut out a con- 

 siderable thickness of rock, the one in the lower, the other in the 

 upper limb of the Ballachulish Fold. Where the Appin Phyllites 

 (2) are bounded on each side by Ballachulish Slates (5), it is a 

 fair presumption that the missing Appin Limestone (3) and Appin 

 Quartzite (4) have been squeezed out to find a resting-place some- 

 where nearer the close of the fold. Even where the Ballachulish 

 Slates are continuous, owing to the Sgorr a' Choise Slide meeting 

 the upper branch of the Ballachulish Slide, it seems necessary to 

 supppose that an unknown amount of rock has been squeezed 

 through the slates, and that these have come together again, effec- 

 tually concealing the passage. It is in this manner that Ave can 

 most readily account for the presence of Appin Quartzite, Lime- 

 stones, and Phyllites in the outcrop of the Ballachulish Core west 

 of the River Creran. 



Two further observations may be recorded. By far the greater 

 part of the Ballachulish Limestone of the upper limb of the 

 Ballachulish Fold consists, in this district, of pale highly-impure 

 calcareous schist (calc-silicate-hornfels east of the River Creran). 

 This suggests that a branch of the Sgorr a' Choise Slide may con . 

 tinue at or near the base of the limestone outcrop, cutting out the 

 black pure portion which one expects to encounter next the Balla- 

 chulish Slates. 



The other point is the occurrence of a narrow phyllitic out- 

 crop, extending south from near the Post Office, for about three- 

 quarters of a mile, in the heart of Ballachulish Limestone. It 

 probably is merely a non-calcareous band interstratified in the lime- 

 stone scries, but it must be admitted that its characters recall those 

 of some parts of the Appin Phyllites — a very heterogeneous group. 



