﻿Yd. 66, ,] SCHISTS OF THE SCOTTISH HIGHLANDS. 613 



Farther south in Glen Creran the Ballachulish Core becomes 

 still more restricted, and here the details of its constitution are not 

 clearly understood. 



The Ballachulish Core between Loch Creran and the 

 margin of the Etive Granite. — On reaching Loch Creran 

 the outcrop of the Ballachulish Core doubles back on itself, and 

 continues thus in a north-easterly direction until lost sight of at 

 the margin of the Etive Granite. In most sections in this part of 

 its course, the core consists entirely of calc-silicate hornfels, repre- 

 senting the Ballachulish Limestone resting, through the interven- 

 tion of the Ballachulish Slide, directly upon the banded portion of 

 the Leven Schists beneath. Near the Loch, however, Ballachulish 

 Slates and Appin Quartzite enter into the constitution of the core. 

 The quartzite is separated from the banded Leven Schists outside 

 by a thin layer of calc-silicate hornfels, on the two sides of which 

 there is, in some sections, a definite discordance of strike. It 

 should be pointed out that this is the only instance known of a 

 conspicuous discordance in connexion with anyone of the big slides 

 of the whole district now under consideration. 



It may be safely assumed that the return outcrop of the Balla- 

 chulish Core and Slide just described is determined by the same 

 synclinal folding as that which is in large measure responsible for 

 the reappearance of these structures farther east in Allt Charnan 

 and the other Windows of Etive (PL XLIV, Sections G & H). 



The apparent absence of the Ballachulish Slide in 

 sections north of the Lairigmor Valley. — Now that the 

 Ballachulish Core has been described in the whole of its known 

 extent, it is obvious that everywhere south of the Lairigmor Valley 

 it is underlain by the Ballachulish Slide. Further, in all sections 

 between Tom Meadhoin and Allt Coire an Easain (14 or 15 miles 

 distant from one another, measured across the strike) this Balla- 

 chulish Slide cuts out much the larger portion of the thick Leven 

 Schist Group, so that the displacement along the slide must be fully 

 14 miles. 



Under these circumstances, it is inconceivable that the slide 

 suddenly dies out along the strike on the north side of the 

 Lairigmor Valley. Rather, we must assume that it really con- 

 tinues, although in this direction it becomes unrecognizable. 

 Fig. 4 (p. 606) shows that the fold of Glen Coe Quartzite, which 

 in the sections south of the Lairigmor Valley displaces so large a 

 portion of the Leven Schists from beneath the Ballachulish Core, 

 closes in Tom Meadhoin (see also Doire Ban, Section D, PI. XL1II, 

 & Section E, PI. XLIV). Xow, if exposures were available, no 

 matter how short a distance to the west of this hill, they would 

 show the Ballachulish Core resting upon a thick mass of' Leven 

 Schists; and if, in addition to this, the main sliding happened to be 

 confined to the Leven Schists, it might w 7 ell become unrecognizable, 

 just as in the actual sections lying north of the Lairigmor Valley. 



