Edinburgh New Philosophical Journal (1849 Edinburgh New Philosophical Journal . edinburghnewphil47edin Year: 1849 - 1849 in the Middle Region of Scotland. 167 it had previously occupied, and would exert an immense lateral pressure on the walls of the valley confining it. Hence it is in situations like this that deep groovings, and especially on vertical surfaces, should be looked for. Something of the same kind is seen at Gareloch, which has a form resembling the figure annexed. Striae and grooves abound in the circular valley x, where the ice must have collected ; those in the bottom are few
Edinburgh New Philosophical Journal (1849 Edinburgh New Philosophical Journal . edinburghnewphil47edin Year: 1849 - 1849 in the Middle Region of Scotland. 167 it had previously occupied, and would exert an immense lateral pressure on the walls of the valley confining it. Hence it is in situations like this that deep groovings, and especially on vertical surfaces, should be looked for. Something of the same kind is seen at Gareloch, which has a form resembling the figure annexed. Striae and grooves abound in the circular valley x, where the ice must have collected ; those in the bottom are few and large ; those on the sides numerous, but generally small. At y, where the valley is contracted to a gorge half a mile in breadth, the bot- tom, being covered with salt water, can no longer be seen ; but great numbers of strii3e are found on the sides, and of various sizes, up to 6 or 8 inches in breadth. At z, where the loch widens out to a mile in breadth, and where the latei'al pressure would, of course,' be greatly re- laxed, the strias disappear, and are no more seen till we come to Row, five miles southward, where the breadth of the loch is again contracted by the point of land at Roseneath. At this place a few are visible (one 16 inches broad) scooped out across the laminae of the clay-slate, which here succeeds to the mica and chlorite slate. The cavity x would serve as a reservoir for the ice, or mer de glace, when the glacier occupying the valley was small ; but the grooves found on the top of the ridge dividing Gareloch from Loch Long (on a surface wonderfully smoothed and levelled; point to glacial phenomena on a grander scale. They can only be accounted for, in my opinion, by assuming that one vast mass of ice filled Gareloch and Loch Long, covering the ridge which divides them, and that the whole moved simultaneously in a SSE. direction, constituting a gla- cier four miles broad, and probably 1000 feet in depth.* The smooth sides, and even or gently-undulating
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