Long before people came to what is now called Wisconsin, the Ice Age shaped the land, and the lower Wisconsin River Valley took its present form when glaciers that covered eastern and northern Wisconsin ten thousand years ago melted away. A huge glacial lake formed at the glacier’s western edge as meltwater pooled, and this part of the river channel was cut by water draining southwest from that lake. Swiftly moving water carried sand and gravel from the melting glaciers and deposited them in the Lower Wisconsin River valley, which would be as much as two hundred feet deeper without that accumulation. Today, the shallow and shifting sands limit the types of boats that can travel on this section of the river. According to some American Indian legends, the Wisconsin River was created by a manitou, or spirit, in the form of a giant serpent that traveled from his home in the great forest to the sea, making a groove across the land that filled with water while streams arose from grooves made by other serpents. At the Wisconsin Dells, large rocks blocked the great serpent’s path, and he pushed his head into a crack and split the stone apart before continuing on; when he grew tired and rested and rolled around, he widened the river channel.