Yol. 68.] THE GLEN OKCHT ANTICLINE. 175 



garnetiferous. In Allt Coire an Easain and in the Efcive sections 

 the limestone is succeeded by a great thickness of grey pelitic mica- 

 schists, free from quartzite and locally garnetiferous; in these 

 north-eastern sections it is quite certain that we are dealing with 

 the pelitic portion of the Leven Schists. 



In one feature, the presence of thin quartzite bands between the 

 limestone and the main mass of the pelitic schists, the sections 

 round the southern rim of the Glen Orchy Anticline differ from 

 many of the Beinn Doirean exposures and also from those afforded 

 by the whole of the tj^pe-region of Ballachulish, including Allt 

 Coire an Easain and G-len Etive. In the type area the Balla- 

 chulish Limestone is, it is true, sometimes extremely siliceous near 

 its junction with the Leven Schists; but, at the same time, actual 

 bands of quartzite are not known to occur iu the mica-schist close 

 to the limestone. We emphasize this difference because the natural 

 way to read the southern sections, if we pay no regard to the Balla- 

 chulish and Glen Coe evidence, is to interpret the limestone as 

 merely marking an episode in the accumulation of the Banded 

 Series. On account of the Ballachulish and Glen Coe evidence, 

 however, we regard the local appearances as deceptive in this 

 matter, and we believe that the quartzite bands overlying the 

 limestone are quite distinct from those of the Banded Series 

 underneath. 



The assumption that a few thin beds of quartzite have locally 

 come into the Leven Schist Group near its junction with the 

 Ballachulish Limestone is, in itself, by no means startling. It is 

 much easier to accept this than to dispute the correlation of the 

 Beinn Doirean, Glen Orchy, Allt Coire an Easain, Glen Etive, Glen 

 Coe, and Ballachulish Limestones, 



(e) The Leven Schists overlying the Ballachulish Limestone east 

 and south of the Glen Orchy Anticline are succeeded by a thick 

 group of pebbly quartzites and black pelitic schists. In 

 Beinn a' Chaisteil and near the head of Loch Awe there is a strong 

 development of pebbly quartzite at the base of the group. In the 

 intervening Glen Orchy district, however, this quartzite is not very 

 recognizable. The line inserted on our map for the base of this 

 pebbly quartzite and black schist group, indexed as 'unclassi- 

 fied schists,' is strictly provisional: we have as yet merely- 

 raised the question of the relation of these schists to the Leven 

 Schists below, without having had time to carry through an investi- 

 gation of the subject. The evidence so far obtained is conflicting : 

 on the one hand, there are suggestions in some localities, especially 

 in Glen Orchy, of a transitional zone linking the Leven Schists with 

 the pebbly quartzites and black schists above ; on the other hand, 

 one cannot help suspecting that this appearance is deceptive, since 

 in the Glen Etive district the pelitic portion of the Leven Schists 

 is capped by outliers of perfectly normal Banded Series and 

 Glen Coe Quartzite. 



The Beinn Doirean range will probably supply the answer to our 



