Glen Fruin* is a quiet secluded glen, about 6 miles in length, extending in a north-westerly direction between Loch Lomond and the Gareloch, and opening off the neck of land which divides these lochs at between 200 and 300 feet above the sea. On the south-east it slopes towards Loch Lomond, of which the Fruin water is one of the principal affluents. On the west it is bounded by a range of hills 1000 to 1200 feet in height, which at the upper extremity, towards Garelochhead, subside into a col or pass of 600 or 700 feet. The upper part of the glen is composed of the mica and clay slates common to the Western Highlands. The lower part is formed of beds of the Calciferous Sandstone series, which have apparently been faulted down between the adjacent Old Red Sandstone and the older Silurian rocks. The huge boulder of mica-schist, resting on the sandstone, at Callendoun, near the mouth of the glen, about 200 feet above the sea (and measuring 28 × 18 × 10 feet), was brought under the notice of the Boulder Committee of the Royal Society of Edinburgh by Mr. R. L. Jack, when engaged on the Geological Survey of the district, and was afterwards visited by the Convener of the Committee, the late Dr. Milne-Home, and figured and described by him in one of the Committee's annual Reports. By some mistake, as we formerly pointed out, † either Mr. Jack, or the Convener in copying his This 250-word extract was created in the absence of an abstract