172 ME. E. B. BAILEY AND ME. M. MACGEEGOE ON [June I912, 



the Beinn Udlaidh Fold has been bent into a gentle secondary anti- 

 cline, which in the vicinity of Beinn Udlaidh is very clearly dome- 

 shaped. This dome is a part of the extensive anticlinal structure 

 already spoken of as the Glen Orchy Anticline. Eeaders familiar 

 with Scottish geology will not fail to realize the essential resemblance 

 between the Beinn Udlaidh Fold bent into the Glen Orchy Anticline 

 and the Carrick Castle Fold bent into the Cowal Anticline, as 

 described several years ago by Mr. Clough [5, fig. 47, p. 204, & 

 pi. X]. 



(B) The Loch Dochard Fold. 



At Loch Dochard the Eilde Flags enclose a mass of garnetiferous 

 mica-schist, with a central core of tremolite-schist representing 

 limestone. Thin quartzite locally occurs at the junction of the 

 flags and the mica-schist. Upon indirect evidence the mica-schist 

 and the limestone have been correlated with the Leven Schists and 

 the Ballachulish Limestone respectively, and it has been suggested 

 that they occupy an anticlinal fold rising up from beneath the 

 Eilde Flags [1, p. 616]. Analogy with the Beinn Udlaidh Fold 

 greatly strengthens this interpretation. At the same time, the 

 relation of the two folds cannot be very simple, for the Leven 

 Schists of Loch Dochard are exposed far to the north-west of the 

 line along which the Glen Coe Quartzite and Eilde Flags close 

 round the termination of the Leven Schists of Beinn Udlaidh. 



(C) Rocks overlying those of the Beinn Udlaidh and 

 Loch Dochard Folds. 



A glance at the map (PI. X) shows that a well-defined succession 

 of rocks follows the Eilde Flags that overlie the other groups 

 included in the Beinn Udlaidh and Loch Dochard Folds. This 

 succession, stated in downward structural sequence, is as follows : — 



{e) Unclassified schists, consisting, in their lower part, of pebbly 



quartzite and black pelitic schist. 

 (d) Thick grey pelitic schists, 

 (c) Thin limestone. 



{h) Banded pelitic schists and quartzite. 

 {a) Quartzite, locally very thick. 



(rt) On the east side of the Glen Orchy Anticline the quartzite 

 overlying the flags first puts in an appearance in Beinn Doirean. 

 When followed southwards it swells out enormously, and where 

 it crosses Glen Orchy it is fully 1000 feet thick. In most of its 

 course the whole of the deposit is somewhat impure, and of a grey 

 or pinkish tint. In Glen Orchy, however, especially in the south- 

 western slopes, there is a thick mass of pure white siliceous quartzite 

 at the top of the group. On both sides of Glen Strae, pebbles can 

 be readily detected, and in Allt a' Ghiubhais^ they are very large and 

 abundant; but elsewhere the quartzite is thoroughly fine-grained. 



1 Pronounced approximately Alt a Gyuse. It is the tributary, shown in 

 PI. X, entering Grlen Strae almost at right angles from the east. 



