OF THE HIGHLANDS. 419 



The two sections (page 420) will perhaps show more clearly the comparative 

 physical structure of the area the one in Perthshire typical of the structure 

 of the eastern, and the other in Cowal of the western part. The eastern 

 section runs from Comrie to Ben Lawers, and in the neighbourhood of 

 Comrie the foliation-planes of the clay-slates, the representative rocks of 

 the Lower Argillaceous zone, dip at high angles towards the northwest. 

 These rocks are also well exposed on the eastern shore of Loch Lubnaig. 

 Further west where the foliation has the same dip, the bedding-planes 

 have at places undergone considerable folding, but generally dip in the 

 same direction as the foliation. Above this zone, and succeeding it to the 

 N.W., conies the Lower Arenaceous zone with its characteristic beds of 

 grit and greywacke, which are all well exposed in the gorge of the Led- 

 nock N. of Comrie, and strike to the S.W. across the summits of Ben 

 Yorlich and Ben Ledi. Tracing the section to the N. it will be found 

 that these rocks continue up Glen Lednock with a gradually decreasing dip 

 from the high angles along the Highland frontier, till near the watershed they 

 become almost flat. On the summit of Meal Na Creige, a mountain overlook- 

 ing Loch Tay, we find an outlier of the Loch Tay limestone zone, consisting 

 of calcareous mica-schist with accompanying sills of epidiorite. To the W. 

 of this the powerful Glen Ample fault truncates the schist, throwing down 

 the Loch Tay limestone, and ushering in the shallow trough of limestones 

 and schists stretching from Glen Beich westward across the Braes of 

 Balquhidder towards the shores of Loch Katrine. 



Descending Meal Na Creig to the other side of Loch Tay we find the 

 Loch Tay limestone and its associated basic rocks dipping N.W. below Ben 

 Lawers. Ascending the sides of the Ben these are succeeded by the 

 garnetiferous schist-zone, and at about 2500 feet are in turn overlaid by 

 the highly contorted phyllites, schistose quartzites, and black graphitic 

 schists of the Upper Argillaceous zone. Down the northern side of the 

 mountain towards Glen Lyon, the Loch Tay limestone with its associated 

 epidiorites again rises to the surface, thus showing that the mountain has 

 been carved out of a syncline of schists. At this point the quartzites of the 

 Upper Argillaceous zone are seen to be cut off by a fault, but elsewhere the 

 passage of the graphite-schists into the quartzite is clearly seen. 



In the western portion of the area the section is taken across Cowal, from 

 Dunoon to Inverary. At Dunoon on the Firth of Clyde the lower argillaceous 

 .zone is exposed along the shore from Hunter's Quay to Innellan, where the 

 dip of the principal foliation is southeast at an angle of 53. In many places, 

 as already observed, the bedding shows evidence of being much folded. Up 

 the Holy Loch towards the north, the phyllites are succeeded by a group 

 of green beds, mica-schists, schistose-grits, and greywackes, the represen- 

 tatives of the Lower Arenaceous zone, dipping southeast at about 53. 



From the head of the Holy Loch they begin to undulate, till at the foot of 

 Loch Eck they give evidence of having been subjected to most violent 

 twisting and contorting. This belt of highly contorted schists extends 

 northwards towards the head of Loch Eck, when again the twisting 

 diminishes and the dip is reversed, being now northwest at much gentler 

 angles. At Ballimore the Loch Tay limestone, with its associated hornblende- 

 schists, is exposed, dipping also northwest, and above it comes the 

 garnetiferous schist-zone, seen in several of the stream-sections. On the 

 shores of Loch Fyne the Upper Argillaceous zone is met with, with its 

 characteristic phyllites and quartz-schists which cross to the north side of 

 the loch and are well exposed near Inveraray. In Glen Aray these rocks are 

 succeeded by the more massive quartzite beds, and limestones, so well 

 developed along the shores of Loch Awe, which belong to the Upper 

 Arenaceous zone, and below which the Loch Fyne phyllites pass in a shallow 

 syncline or trough. 



