Vol. 68.] THE GLEN OECHY ANTICLINE. 173 



The north-western side of the Glen Orchy Anticline is in large 

 measure obliterated by the Etive Granite ; but in Allt Coire an 

 Easain, within the boundarj-fault of the cauldron subsidence of 

 Glen Coe, thin quartzite follows the Eilde Elags in a perfectly 

 regular manner. It will be noticed that in the diminished thickness 

 of its quartzite Allt Coire an Easain agrees very closely with Beinn 

 Doirean, which it directly faces across the anticline of Glen Orchy. 

 The thinning in Allt Coire an Easain is but local, moreover, and 

 2 or 8 miles to the north-west the quartzite emerges in great 

 force from beneath an unconformable covering of Glen Coe lavas. 

 It is also exposed in the Windows of Etive half a dozen miles west 

 of Allt Coire an Easain, and here again it is of considerable thick- 

 ness. In all these north-western exposures the quartzite is fine- 

 grained, white, and highly siliceous, and it has been proved beyond 

 reasonable doubt to belong to the horizon of the Glen Coe Quartzite 

 fl , pp. 607 & 609]. Accepting this correlation, it is fair to draw the 

 following important conclusion. The Eilde Elags, although 

 underlain by Glen Coe Quartzite in Beinn Fdlaidh, 

 are overlain by the same group all round the rim of 

 the denuded Glen Orchy Anticline from Allt Coire an 

 Easain to Beinn Doirean. This involves, of course, the 

 existence of a large-scale recumbent fold. 



It may be pointed out that the rather impure character of the 

 Glen Coe Quartzite, in the upper limb of the fold just mentioned, 

 can be paralleled in the type region in many outcrops north of Loch 

 Leven. In these, however, the somewhat impure variety is as a 

 rule closely associated with the more conspicuous white rock, which 

 is justly regarded as typical of the Glen Coe horizon. 



The thinning of the Glen Coe Quartzite in Allt Coire an Easain 

 and Beinn Doirean deserves closer investigation than we have been 

 able to afford, for the time at our disposal was strictly limited. 



(b) The Glen Coe Quartzite, everywhere in its course around the 

 Glen Orchy Anticline, except perhaps in Allt Coire an Easain, is 

 overlain by a Banded Series of grey mica-schist with quartzite 

 ribs. Where it is exposed in the Windows of Etive, this Banded 

 Series has been shown to be that part of the Leven Schists which 

 normally comes next to the Glen Coe Quartzite. 



(c) In the Beinn Doirean range the Banded Series is overlain: 

 immediately by a somewhat calcareous tremolite-schist which 

 varies from about 5 to 30 feet in thickness. This impure highly- 

 metamorphic limestone is more persistent in a northerly direction 

 than the underlying Banded Series and Glen Coe Quartzite, so that 

 for some few miles it rests directly upon the Eilde Elags. 



It is found again, with about the same thickness, along the 

 southern rim of the Glen Orchy anticline, where it has been traced 

 for considerable distances. It is not so highly metamorphic here 

 as in Beinn Doirean. On the summit south of Glen Lochy, for 

 example, where reference to Mr. Kynaston's field-maps shows that 



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