﻿612 ME. E. B. BAILEY ON RECUMBENT FOLBS IN THE [Nov. I9IO,. 



Quartzite and Striped Series, leading, in places, to an actual dis- 

 appearance of these two groups. Reference to Section G shows, 

 that S" is not homologous, but complementary, to its neighbours S' 

 and the Ballachulish Slide beyond. 



Another slide (S'", Sections G & H), belonging to the com- 

 plementary series, bounds the Sgorr a' Choise fold on the- 

 south-east. This slide was first detected by Mr. Clough at the very 

 beginning of our knowledge of the existence of such structures 

 in the district. He found it in the burn section at the northern 

 foot of the Sgorr, where its presence is indicated (1) by the direct 

 conjunction of the cream-coloured portion of the Ballachulish 

 Limestone with the Ballachulish Slates on the north-west ; and 

 (2) by definite, though none too conspicuous, evidence of shearing 

 accompanied by disruption. 



At the summit of Sgorr a' Choise Mr. Clough showed that the 

 continuation of this slide (S'") was further marked by the attenua- 

 tion of both the Ballachulish Slates and the Appin Quartzite. 

 These two groups, developed in force on the north-west side of the 

 Sgorr a' Choise Fold, are reduced to about 3 feet each in thickness, 

 where, passing round the nose of the fold, they intervene between 

 the cream-coloured edge of the Ballachulish Limestone on the one 

 side and the white Appin Limestone on the other. 



Attention must now be directed to one of the main features 

 characterizing the illustrations included in PI. XLIV. In Sections 

 F-H of this plate the various slides affecting the Ballachulish Core 

 are indicated as sharing in the general folded structure of the core 

 itself. Except in the case of the Ballachulish Slide, this assumption 

 has not been justified by direct evidence, owing, probably, to the 

 extreme difficulty of following the minor slides from point to point. 



The Glen Creran development of the gape of the Ballachulish 

 Core (PI. XLIV, Section H) is very similar to that just described. 



The Ballachulish Slide is again conspicuously double, including 

 between the two planes which have been mapped a thick develop- 

 ment of the grey portion of the Ballachulish Limestone, associated 

 in places with outcrops of the Ballachulish Slates. On the north- 

 west this grey limestone comes into direct contact with the banded 

 portion of the Leven Schists ; on the south-east its regular outcrop^ 

 marches side by side with a folded complex of Appin Quartzite, 

 Limestone, and Phyllite. The Appin Phyllites in many exposures 

 contain thin black seams indicating the presence of the transition 

 series which connects this phyllite group (2) with the Cuil Bay 

 Slates (1). 



The gape of the fold is narrower than it is farther north, and 

 there is nothing in Section H to correspond with the Beinn Bhan 

 syncline. The continuations of the Gleann an Fhiodh and Sgorr a' 

 Choise synclines, or equivalent structures, are, however, clearly- 

 recognizable. 



