166 MK. E. E. BAILEY AND ME. M. 3IACGREG0E ON [June I9I2, 



rocks included in Groups 1-6 of the foregoing stratigrapliical table. 

 Pig. 1 (p. 165), which shows the new district in relation to the old, 

 has been constructed on this basis, and illustrates very clearly bow 

 the Ballachulish Core has been bent into a widely-extended secondary 

 syncline in Glen Creran and into a corresponding anticline in 

 Glen Orchy. The presentation of the evidence which has enabled 

 us, as we believe, to trace the outcrop of the Ballachulish Core 

 round the rim of the denuded Glen Orchy Anticline is the main 

 feature of the following account. Incidentally, however, a de- 

 scription is given of a particularly convincing example of a 

 recumbent fold in Beinn L'dlaidh, and of an important inversion 

 of the Ballachulish Core in Beinn Doirean. 



II. HlSTOET OF ReSEAECH. 



A comparison between our map (PI. X) and the adjacent northern 

 corners of Sheets 45 & 46 of the Geological Survey Map of Scot- 

 land shows many new features of importance. The subdivision 

 of the schists did not attract special attention when the original 

 mapping of this particular district was carried out. Before 

 publishing Sheet 45, however, a joint traverse of a few days' 

 duration was undertaken in 1907 by Dr. Home, Mr. Clough, and 

 Mr. J. B. Hill, to revise the boundary-line of the Eilde Flags, or, 

 as they were called at that time, the ' Moine Series.' Por one day 

 Mr. Kyiiastou was also present, as he happened to be in Scotland 

 on furlough from the Transvaal. The party kept to the east 

 of the fault which runs up Glen Strae, and for this part of the 

 district the line engraved on the published map to represent 

 the boundary of the ' Moines ' has been of great service to us. 

 During the same visit the quartzite and mica-schist of Beinn 

 Udlaidh were differentiated from the ' Moine Series ' along the 

 bottom of Glen Orchy, where this valley enters Sheet 45. The 

 quartzite of tlie Beinn Udlaidh outcrop was considered to be quite 

 distinct from that which occurs south-west of the ' Moine Series ' 

 farther down the glen. In the following pages we suggest, how- 

 ever, that these two quartzites are on one and the same horizon; 

 but this is a matter wherein there is still room for differences in 

 regard to interpretation. The results of the joint traverse were 

 incorporated [2, p. 38] in a short account published in the Memoir 

 dealing with Sheet 45. 



In 1908 one of the present writers accompanied Mr. Clough 

 [3, p. 63] on a second brief visit to the district ; it was hoped, 

 and the hope was justified, that light would be thrown upon the 

 stratigraphical succession of the schists in the complicated country 

 north-west of the Etive Granite. Much was learnt during the 

 traverse, mainly as a result of Mr. Clough's experience in mapping 

 Highland schists. The Beinn Udlaidh quartzite and mica-schist 

 were carried eastwards into Sheet 46, where the latter had already 

 been in part separated from the ' Moines ' by the late Mr. Grant 

 Wilson. The folded nature of the Beinn Udlaidh rocks was 



