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ANCIENT SEA-MARGINS.

famed Black Mount, over which the road climbspainfully before descending into Glencoe. Towardsthe south is a steep and somewhat hollow-sidedmountain called Ben Doig, under which a valleyopens to conduct away the spare waters of the lake.This lake is Loch Tulla, and the valley is that of theUrchay. The geologist and lover of the picturesquewould find much to admire in the great primitivemountains of the district; and the former wouldobserve with surprise that, on the sides of one of thegroup (the above-mentioned Black Mount), there isa thick though irregular coat of clayey alluvialmatter to heights not less than 1000 feet above thelevel of the sea. We are here about forty milesfrom Glen Boy.

What chiefly concerns us for the present with thebasin of Loch Tulla is the clear and distinct water-marks which can he traced along the faces of thehills, indicating the former presence of a stationarybody of water, at levels much above the present lake.Mr Milne, who first announced the character of theselines, speaks of three which he traced all round thelake. He says—“ Their perfect horizontality, whichI ascertained by a spirit-level, looking at them fromtwelve or fifteen different places along the banks ofthe lake—their general conformity in sweeping roundheadlands, and retiring into valleys or burn-courses—and the extent of flat surface at the levels of thedifferent shelves, afford convincing and irrefragableproofs,” that they are what he describes them to be—