Edinburgh New Philosophical Journal (1849 Edinburgh New Philosophical Journal . edinburghnewphil47edin Year: 1849 - 1849 in the Middle Begion of Scotland. 181 The rock 0 E, consists of beds of conglomerate and sand- stone dipping to the west at an angle of 5° or 10°. The ra- vine at the Bridge of Allan is from 150 to 200 feet deep. C C is a deposit of clay, of which the lower half has distinctly the chai'acter of the older diluvium, being very firm, and inclosing striated blocks of chlorite slate and other travelled stones. It descends to the water-course at a, and the deep cut b r c made
Edinburgh New Philosophical Journal (1849 Edinburgh New Philosophical Journal . edinburghnewphil47edin Year: 1849 - 1849 in the Middle Begion of Scotland. 181 The rock 0 E, consists of beds of conglomerate and sand- stone dipping to the west at an angle of 5° or 10°. The ra- vine at the Bridge of Allan is from 150 to 200 feet deep. C C is a deposit of clay, of which the lower half has distinctly the chai'acter of the older diluvium, being very firm, and inclosing striated blocks of chlorite slate and other travelled stones. It descends to the water-course at a, and the deep cut b r c made on it for the railway, which occupies the hollow r, as- sures us that the clay is not a mere superficial covering which may have slid down from above and concealed the face of the rock, but the remnant of a deposit which once filled, or nearly filled, the ravine. The depth, in the direction r c, is, at least, 80 feet. The rock is not visible on this side, but it reappears in a quarry half a mile westward with the usual dip, at an elevation exceeding that of the point c, and is also seen on the left of the railway farther north. The legitimate conclusionsdeducible from the facts, I think, are these; that the ravine was excavated in the rock by a river, and nearly to its present depth ; that the land then sunk under the sea, and remained there during the deposition of the older and newer boulder clay, which filled up the ravine wholly or par- tially ; that after this the land rose again above the water, when the river sought out and re-opened its old channel. Examples of similar phenomena are probably not rare. There is a mass of dark coloured clay, 40 feet in height, forming the south bank of the Water of Leith at Coltbridge, which seems to indicate that that portion of the bed of the stream was excavated before the diluvium was deposited. It is alluded to in Sir James Hall's paper. In the parish of Muiravonside, westward from Linlithgow, the River Avon flows between two preci
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