part 2] THE SOUTH-WEST HIGHLANDS OF SCOTLAND. 117 



One last point deserves notice before we turn eastwards from 

 Loch Creran. Inspection of PI. I shows a very limited dis- 

 continuous outcrop of the Iltay Nappe between the Strath- Appin 

 Fault and the Ballachulish Granite. Narrow exposures of massive 

 white quartzite (pebbly in the south with quartz and felspar, and 

 fine-grained in the north) have been met with intermittently along 

 one particular line of strike. They probably represent little 

 klip pen of the Garbh-Ard (Islay) Quartzite. They lie within the 

 belt of Banded Series, if this term be used in its broadest sense ; 

 but for a mile on the south-east side grey phyllite is the prevalent 

 rock of the district. 



Outcrop of the Iltay Nappe north of the Loch-Awe Nappe. 



It is here proposed to trace the outcrop of the Iltay Nappe in 

 its eastward course between Loch Etive and Loch Awe, and 

 onwai'ds past Dalmally into Perthshire. ^ The only part of this 

 description that is definitely new refers to the discontinuous 

 portion of the outcrop included within the contact-aureole of the 

 Etive Granite (fig. 7). 



Ballappel Foundation and Iltay Nappe, north-west 

 of the Loch -Awe Nappe, — North-east of the Pass-of-Brander, 

 or Strath- Appin, Fault there is an imposing display of the Banded 

 Series of the Leven Schists all the way from Loch Creran to within 

 about a mile of Loch Etive. Grey phyllitic material (notably 

 hornfelsed, and displaying pitted surfaces indicative of cordierite 

 wherever it comes within a mile of the Etive Granite) is associated 

 with perhaps pi'eponderant fine-grained, grey, quartzose schists, 

 often interlaminatecl with dark seams. 



From our detailed knowledge of the geology of the head of Loch 

 Creran (1914; 1916, p. 51), the whole of this tract can be referred 

 with confidence to that portion of the Ballappel Foundation which 

 immediately underlies the Ballachulish Nappe. There is no very 

 marked change until, east of the angle of the Biver Esragan, a 

 massive pebblj'- quartzite figures prominently in the crags of the 

 hillside, 2 miles in from the left-hand margin of fig. 7. The 

 quartzite dips steeply, and its outcrop measures 300 ^^ards across 

 the strike. As seen in the crags it is but little sheared, and 

 contains subangular pebbles, often half an inch long, consisting of 

 quartz and subordinate felspar ; some of the quartz is blue. 



Although the incoming of quartzite in bulk is abrupt, exami- 

 nation reveals the presence of minor pebbly quartzite-bands in the 

 banded quartzopelitic hornfels (pitted with cordierite) within a 

 zone about 400 yards wide bordering the quartzite on its northern 

 side. This belt of interbedded phyllite and pebbly quartzite I 

 have seen at intervals at the margin of the pebbly quartzite far 

 into Perthshire, where it is conspicuously displa3^ed, for instance, 

 in the Pass of Killiecrankie. The Perthshire sections which 



1 See also 1922, Eeport A, par. 8. 



