﻿Vol. 66.~] SCHISTS OF THE SCOTTISH HIGHLANDS. 591 



Dr. Peach had a very brief association with the district, but with 

 Mr. Maufe and the writer he realized the separate existence of two 

 quartzites, pebbly and non-pebbly respectively [29]. Of these the 

 pebbly quartzite (Appin Quartzite) was correlated by Mr. Wilson 

 and Dr. Peach with the Schiehallion Quartzite of Perthshire [30], 

 and was regarded by them as unconformable, owing to the fact 

 that in certain sections it comes into transgressive contact with 

 several distinct rock-groups. The Appin Quartzite is not peculiar 

 in this respect, however, since all the other groups of the district 

 are, on occasion, equally transgressive in their behaviour, and the 

 present writer holds that the observed phenomena are due entirely 

 to the intervention of fold- faults. It is not clear what bearing this 

 new interpretation has upon the theory of ' the unconformable 

 quartzite ' advocated by several authors elsewhere in the Highlands, 

 but it may be recalled that this theory of unconformity, as applied 

 to Perthshire, has been opposed for many years by Mr. G. Barrow. 

 It is not only in this matter that uncertainty exists. In the 

 Summaries of Progress of the Geological Survey, correlations have 

 been suggested between the rock-groups of the district now de- 

 scribed and those of other parts of the Highlands (for instance, 

 Ardrishaig and Loch Fyne). But the views expressed are certainly 

 premature : since, until the fold-faults came to be recognized, there 

 was great confusion even in such matters as involved strictly local 

 correlation. Thus, for instance, the Appin Phyllites and the Leven 

 Schists were regarded as one and the same group, and as such 

 were correlated with the Ardrishaig Phyllites. This resulted from 

 the extraordinary complications introduced by fold-faults in what 

 was for some years regarded as the typical stream-section afforded 

 by the lower part of Gleann an Fhiodh (near Ballachulish), and the 

 tributary of this glen which lies on the north-east of Sgorr a' Choise. 



Mr. Maufe has assisted me perhaps more than anyone else ; in 

 fact, this paper is the outcome of a joint traverse which we under- 

 took last autumn to see the more important sections together. The 

 result of this trip was the clearing up of various uncertainties, thus 

 permitting a directness and confidence of description hitherto im- 

 possible. The main advance was the establishment of the anticlinal 

 nature of the fold of Ballachulish Slates separating the Beinn Bhan 

 and Gleann an Fhiodh synclines (PI. XLIV, Sections F & G). At 

 an earlier date I was indebted to Mr. Maufe for the identification 

 of the Appin Quartzite outcrop at the head of Loch Creran, and the 

 discovery of an obvious discordance along its south-eastern margin. 

 The district actually mapped by Mr. Maufe is a large one, extending 

 from Glen Etive to Glen Coe, and including the great recumbent 

 fold already mentioned as the first to be recognized in this region. 



In conclusion, I wish to thank Dr. Home and Mr. Cloughfor 

 the facilities which they have afforded during the investigation of 

 this complicated tectonic problem. 



