Yol. 55.] IX THE REGTOX OF LOGS AWE. 483 



large amount of argillaceous material, either of the green calcareous 

 variety belonging to the Ardrishaig Series or the dark variety of 

 phyllite belonging to the Loch Awe div^ision. At one place near 

 Lochan-na-Cuaig much extravasated quartz was seen, some of which 

 had shared in the folding and some was of later date. The purplish 

 bands represent the dark partings of phyllite. These beds are con- 

 tinued on the north side of the Pass of Brander, where they are 

 well seen at the Falls of Cruachan. On the north side of the Pass 

 they are, however, if anything, more altered, the dark phyllitic 

 partings being here represented by coarse mica. This epidotic banded 

 limestone is intensely hard, and stands out in the section like a 

 quartzite. The limestone has been converted into calc-hornfels, 

 and is very prevalent in this condition along the Pass of Brander. 

 When in this state it will only effervesce feebly with hydrochloric 

 -acid, and in many cases not at all. 



A specimen from Tervin showed under the microscope * dirty 

 aggregates of epidote, carbonates, etc' (5704). Another specimen, 

 in which the alternations of phyllite were well seen, is thus described 

 by Mr. Teall:— 



(5705) Pass of Brander. — Fine-grained banded rock. Alterna- 

 tions of black and greenish-grey bands. The dark bands are mainly 

 composed of mica (phyllite) ; the lighter bands consist of quartz, 

 epidote, carbonates, etc. 



(5706) North side of the Pass of Brander. — Pale grey compact 

 rock. Confused aggregate of granulitic quartz and felspar, zoisite, 

 :and perhaps epidote. 



In another specimen, from the Falls of Cruachan, a white double- 

 refracting garnet was detected by Mr. Teall. 



A rock very similar in character to these occurs in Gleann 

 Strae, about | mile north of Dhuletter. It is here a greenish rock 

 containing crystals of epidote, with intercalations of black phyllite 

 A specimen was sliced, and is described as follows : — (5708) Dark 

 greenish compact rock. Quartz, felspar, carbonates, etc. 



Exposures of the limestone are seen here and there in its proper 

 position at the top of the Ardrishaig Series between Dalmally and 

 Socach. At Socach, where the Ardrishaig phjdlites have become 

 coarsely crystalline, a good exposure of limestone is seen capping 

 the hill of Barr Dubh. A good deal of micaceous schist is mixed in 

 with it, and biotite and actinolite are largely developed. 



The following sections, described by Mr. Teall, are from altered 

 limestones in the highly altered area to the north of the Strath of 

 Orchy : — 



(5701) 1| mile north of Inverlochy. — A dark medium-grained 

 schistose rock. Carbonates (calcite), chlorite, quartz, pale brown 

 mica, garnets, and iron-ores. 



(5698) J mile south of Beiun Donachain. — A medium-grained, 

 dark-grey, schistose, calcareous rock. Micaceous lustre strongly 

 marked on the uneven planes of schistosity. A confused aggregate 

 of pale-brown biotite, white mica, chlorite, calcite, felspar, and 

 epidote. Calc-biotite-schist. 



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