﻿Yol. 66.~] SCHISTS OF THE SCOTTISH HIGHLANDS. 597 



This rock figures largely in both the Appin and the Ballachulish 

 Cores, and every where its characters are the same. 



The passage-zone, commonly known as the Striped Series (4'), 

 links the Appin Quartzite with the Ballachulish Slates ; it is 

 perhaps as thick as the quartzite itself, and is certainly as widely 

 distributed. About 500 feet of the Striped Series are seen in an 

 unreduplicated section on the face of Sgorr Dhearg, in the Balla- 

 chulish Core south-west of the village. As the name implies, the 

 Striped Series is characterized by an incessant alternation of white 

 and grey quartzite and quartzitic material with dark-grey and black 

 pelitic seams. At the one end quartzite predominates, and pebbly 

 seams are not uncommon ; at the other end black slate predominates, 

 and pebbly seams are rare or absent. A few calcareous layers are 

 locally found in the heart of the Striped Series. 



(5) The Ballachulish Slates are black pyritous slates, 

 generally in the condition of roofing-slates ; in places, however, the 

 slaty character is destroyed by strain-slip cleavage. They are 

 widely developed in both the Appin and the Ballachulish Cores, 

 where they have been extensively quarried, especially in the latter. 

 It is interesting that these slates never show conspicuous mica- 

 flakes, although the latter are common both in the Appin Phyllites 

 (2) and in the Leven Schists (7). The group yields very sombre, 

 spotted, splintery hornfelses in proximity to the Ballachulish 

 Granite ; the reteution of the black colour is, however, sufficiently 

 diagnostic. 



(6) The Ballachulish Limestone consists of two parts — a 

 black, or dark grey, sandy, banded limestone, merging into the 

 Ballachulish Slates, and a cream-coloured sandy limestone merging 

 into the Leven Schists. 



Several clear sections showing the two parts of the limestone in 

 natural relation are afforded by the Appin Core, and in all save the 

 Spean section, at the northern extremity of our district, the two 

 are continuous. In the Spean section there appears to be a parti- 

 tion of phyllite of the Leven Schist type. The more important 

 sections are as follows : — East of Onich, on the hill-top above the 

 road, the two parts of the limestone are found in contact in natural 

 position between the Ballachulish Slates and the Leven Schists. 

 West of Onich, on the sea-shore, the same features are repeated, 

 save that here the cream-coloured edge of the limestone comes, 

 through the intervention of the Fort William Slide, into contact 

 with the Eilde Flags (9). Another excellent section, showing the 

 passage from the grey into the cream-coloured limestone and from 

 the latter into the Leven Schists, is afforded by the tributary burns 

 south of Glenstockdale House, about a dozen miles south of the 

 Onich sections just mentioned. Farther south again, on the main- 

 land side of the hollow which almost makes an island of the Port 

 Appin peninsula, the cream-coloured edge of the limestone is very 

 typically exposed, passing into the Leven Schists on the one side 



