The Geology of Coical. 87 



taken place at the time of the production of the streakiness seen on 

 the foliation planes of the adjoining phyllites, and probably both were 

 accompaniments of the production of foliation. The elongation seems 

 comparable to the distortion of fossils on the cleavage planes of slate. 



The behaviour of the several groups towards the great central 

 anticline of foliation pi-esents some very interesting features. " In 

 ' the anticline ' folds (says Mi-. Clough) with axes hading north- 

 west, it is the under limbs of anticlines that have a tendency to be 

 most thinned, whether we are on the south-east or north-west side 

 of the centre of the anticline. Hence, if we regard the early ' pre- 

 anticline' folds as having originally had axes hading north-west, the 

 same law of the greater thinning of under limbs of anticlines prevails 

 in both ; and we may conclude that th^ source of the pi'essure 

 which produced them both lay to the north-west of the area being 

 described, and that the pressure was outwards from the Highlands 

 in a south-east direction. The evidence in the north-west of Scot- 

 land is now well known to show that there were there, partly at all 

 events in Post-Cambrian times, mountain-making forces pressing 

 outwards from the Highlands in a W.N.W. direction. Hence the 

 central Highlands represent an area from which earth-moving forces 

 have pressed outwards, on the one side in a west-north-westerly and 

 on the other side in a south-easterly direction." 



The bulk of the schists are regarded as probably of sedimentary 

 origin. Chapters iii and iv are devoted to a detailed description 

 of them. The albite schists present some curious features. They 

 occur mainly towards the anticline centre, and at Lochgoilhead all 

 the more micaceous schists contain albites. The albite spots are 

 almost confined to the micaceous and chloritic beds, and it is doubtful 

 whether they occur at all in the more quartzose pebbly beds. It is 

 inferred from their never showing any appearance of stretching that 

 the albites are of later age than the mass of the movements affecting 

 the rocks in which they occur. 



The " Green Beds " present another curious group of rocks. 

 These are of a mixed and variable character ; for on the north- 

 west side of the anticline about one-half of the group consists of 

 other schists, whilst on the south-east side the different outcrops 

 are comparatively unmixed. They are described for the most part 

 as epidote-chlorite schists, and are often intersected by thin quartzose 

 veins coloured green by epidote [? the " epidosite " of Sterry HuntJ. 



Of the schistose igneous rocks, the epidiorites, hornblende schists, 

 and related chlorite schists, associated with the presumed sedimentary 

 series, are most abundant towards the side of Loch Fine. They are 

 generally harder than the schists, and thus help in working out 

 the physical structure. It is believed that they represent old 

 intrusions rather than lava-flows. There is a special danger of con- 

 fusing some of these old igneous rocks with the " green beds." In 

 the area between Stralachlan and Loch Fine, these epidiorites, etc., 

 form huge irregular masses behaving on a large scale like sills with 

 irregular protrusions, the longer axes of which coincide with the 

 strike of the main mass, and of the quartzites in which they are 



