﻿604 ME. E. B. BAILEY ON KECUMBEET EOLDS IN THE [Nov. I9IO, 



The main feature of the Aonach Beag Core is the degree to which 

 it has suffered from secondary disturbance. The core has been 

 treated as a bed and has been folded into a syncline, which descends 

 with highly inclined sides to a depth of probably not less than 

 2000 feet (fig. 3 and PI. XLIII, Sections A-C). Once a fold-core 

 has been buckled in this fashion, it is obvious that its development, 

 as a fold-core, must have come to an end. Henceforward its role in 

 the scheme of mountain-building must have been entirely passive. 



The secondary folding of the Aonach Beag Core has been 

 accompanied by the production of a very striking vertical strain- 

 slip cleavage, which affects a belt of country about a mile wide. 

 This strain-slip cleavage cuts and displaces quartz-veins in the 



Pig. 3. — Looking up Glen Xevis from Stob Ban. 



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y y/U 



[The Aonach Beag core of Ballachulieh Limestone folded into a syncline is 

 well seen in Aonach Beag, 4051) feet above sea-level, and also in the low 

 hill in the middle distance.] 



schists which it traverses ; it is, therefore, analogous in behaviour 

 to the secondaiy strain -slip cleavages described by Mr. Clough [34] 

 and Mr. Wright [35] from Cowal and Colon say respectively. In 

 agreement with the views expressed by these authors, it would 

 seem that the quartz-veins in the present instance were formed in 

 connexion with the development of the Aonach Beag Core, and 

 were buckled and broken when the latter suffered its subsequent 

 corrugation. 



(c) The Ballachulish Core. 



In the ridge extending north-westwards from Stob Ban the con- 

 tinuation of the Aonach Beag syncline is clearly exposed, and is 

 followed on the south-east by a second syncline involving a portion 

 of the Ballachulish Core (PI. XLIII, Section C) x ; the distance 



1 The Ballachulish Core is here shown as distinct from the Aonach Beag 

 Core, since it is fuller than the latter, although it lies farther to the south- 

 east, in which direction it unquestionably closes. 



