Driftless Area
13,000 sq mi (33,670 sq km), largely in SW Wis. but extending into SE Minn., NE Iowa, and NW Ill. The continental glacier which covered most surrounding regions did not touch this area, which abounds in caves and sinkholes and has residual, well-drained soil. Because it was an important lead-mining region, the federal government prohibited farming in the Driftless Area until the 1840s. It was then settled by European immigrants.
Isolated patches of rough terrain in the unglaciated
Driftless Area, primarily in southwestern Wisconsin, stand out from the
surrounding, smoothed glaciated ground. Thoroughly dissected by
tributaries of the Mississippi River, the topography within these
"islands" was engulfed but never overridden by the ice. The appearance of
the Driftless Area landscape today probably is much like that of adjacent
glaciated landscapes
prior to the first Pleistocene ice advance.