Glacial Lake Wisconsin

Glacial Lake Wisconsin. Ice Age National Scientific Reserve. , About 15,000 years ago these bluffs became islands in a great body of water called Glacial Lake Wisconsin. Shorter bluffs like Ragged Rock were sometimes totally submerged under icy waters more than 80 feet deep. At its maximum the lake extended more than 80 miles to the north (ahead), east, and south., The lake formed when glacial ice dammed drainage channels near Baraboo and the Wisconsin Dells. As the climate warmed, great torrents of meltwater flooded the region. When the ice dam eventually melted, the lake drained away and carved the beautiful sandstone cliffs at Wisconsin Dells., [Graphic:] , , Island , , Floating ice block , , Embedded boulder , , Partially submerged bluff , , Deposited erratic boulder , , Lake bottom sediments, The flat lakebed, crossed today by Interstate Highways 90 and 94, is composed chiefly of sand lake-bottom deposits. Rocks and boulders from distant sources have also been found. Geologists believe these erratics were rafted across the glacial lake by small icebergs., These bluffs became Ice Age islands when Glacial Lake Wisconsin flooded the area. The glaciers themselves did not extend this far west or they would have crushed the fragile bluffs.