Carbonate rocks (rock formations composed primarily of limestone or dolomite) underlie about one-third of Wisconsin. These formations occur in a U-shaped belt beginning in southern Polk County in the northwest, extending through most of southern Wisconsin, and covering the entire eastern side of the state from the Illinois border to the Door Peninsula. These rocks are fractured, and vertical and horizontal fractures are the primary pathways for groundwater movement. These rocks are also soluble, and percolating water from precipitation can enlarge some fractures to form conduits, caves and sinkholes that are the hallmarks of a karst landscape.
Soil Science Extension
University of Wisconsin Madison