_Baraboo lake._--Another lake which existed in this region when the ice was here, occupied the valley of the Baraboo and its tributaries when the ice blocked the valley at Baraboo. This lake occupied not only the valley of the Baraboo, but extended up the lower course of every tributary, presumably rising until it found the lowest point in the rim of the drainage basin. The location of this point, and therefore the height of the lake when at its maximum, are not certainly known, though meager data on this point have been collected. At a point three miles southeast of Ablemans on the surface of a sandstone slope, water-worn gravel occurs, the pebbles of which were derived from the local rock. On the slope below the gravel, the surface is covered with loam which has a suggestion of stratification, while above it, the soil and subsoil appear to be the product of local rock decomposition. This water-worn gravel of local origin on a steep slope facing the valley, probably represents the work of the waves of this lake, perhaps when it stood at its maximum height. This gravel is about 125 feet (aneroid measurement) above the Baraboo river to the north. Further evidence of a shore line has been found at the point marked T, Plate II. At this place water-worn gravel of the local rock occurs in much the same relationship as that already mentioned, and at the same elevation above the Baraboo river. At a point two and one-half miles southwest of Ablemans there is local water-worn gravel, with which is mingled glacial material (pieces of porphyry and diabase) which could have reached this point only by being carried thither by floating ice from the glacier. The level of this mixed local and glacial material is (according to aneroid measurement) approximately the same as that of the other localities. When the ice melted, an outlet was opened _via_ the Lower narrows, and the water of the lake drained off to the Wisconsin by this route. Had the ice left no drift, the lake would have been promptly drained when the ice melted; but the lake did not entirely disappear immediately after the ice retreated, for the drift which the ice left obstructed drainage to the east. The moraine, however, was not so high as the outlet of the lake while the ice was on, so that, as the ice retreated, the water flowed over the moraine to the east, and drew down the level of the lake to the level of the lowest point in the moraine. The postglacial cut through the moraine is about ninety feet deep.