LaCrosse Ice Falls
April 16, 2004
The above photo of this road side "waterfall" was taken in early March in southeastern Minnesota. Water seeping out of the high bluffs above the Mississippi River along Highway I-90, across the river from LaCrosse, Wisconsin, has frozen to form these dramatic ice falls, only a few feet from the shoulder of the roadway.
The Mississippi River probably did not occupy its present course before the Pleistocene Period. Pleistocene ice advances tied up millions of cubic kilometers of water in the form of glacial ice, but during each ice retreat, the Mississippi River valley was scoured with huge discharges of meltwater. These floods are responsible for the steepness of the bluffs, which consist of Prairie du Chien dolostone and are capped with Cambrian sandstone. Icings such this are examples of aufeis.