. The Quarterly journal of the Geological Society of London. and, if it is to clearColonsay after leaving the Sound, it must bend sharply south-eastwards, as shown in fig. 3. According to this interpretation,the Great Glen Fault can scarcely run between the Sound ofIona and Colonsay, for the effect of this fault, with its greatdownthrow to the south-east, would be to displace the outcropof the Moine Thrust south-westwards. On the other hand,it does seem likely that the fault passes south-east of Colonsay, 138 ME. E. BATTEBSBT BAILEY OX [vol. lxxii, since, on crossing the line laid clown for it
. The Quarterly journal of the Geological Society of London. and, if it is to clearColonsay after leaving the Sound, it must bend sharply south-eastwards, as shown in fig. 3. According to this interpretation,the Great Glen Fault can scarcely run between the Sound ofIona and Colonsay, for the effect of this fault, with its greatdownthrow to the south-east, would be to displace the outcropof the Moine Thrust south-westwards. On the other hand,it does seem likely that the fault passes south-east of Colonsay, 138 ME. E. BATTEBSBT BAILEY OX [vol. lxxii, since, on crossing the line laid clown for it in fig. 3, one finds rocksof the Highland Schist Complex extending south-westwards as farat least as the outcrop of the Loch Skerrols Thrust. Mention has already been made of the Bowmore Sandstone. Asexposed along the shore between Bowmore and Laggan, this group Fig. 3.—Suggested continuation of the Great Glen Fault acrossIslay, with the Moine Thrust on the north-ivest side perhapsequivalent to the Loch Skerrols Thrust on the south-east side(in Islay).. consists of compact, hard, fine-grained sandstone, Aveathering withbrown surfaces, but grey on a fractured face. A very occasionalsolated pebble of quartz or felspar can be detected, sometimes ofair size. The rocks are extremely homogeneous, and therefore the part 2] THE I SLAY ANTICLINE. 139 bedding is very faintly marked. They are much shattered, as wellas considerably sheared. Near Laggan their weathering tints arepaler than usual, and some of the group might be styled finefelspathic quartzite. At Blackrock pebbly beds occur, and are re-presented by slides 6231-6236 in the Geological Survey collection. As mentioned above, there is often a difficulty in making out thedip of the Bowmore Sandstone. Appearances certainly suggest avery general inclination towards the south-east at angles varying,according to Mr. Wilkinson, between 10° and 40°. Several competent judges, including Dr. Peach, have beenimpressed by the resemblanc
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