While drift from early ( pre-Illinoian) glaciations has been found in some parts of the region, much of the incised Paleozoic Plateau of Wisconsin and northwestern Illinois has no evidence of glaciation. Glacial drift includes unsorted material called till and layers deposited by meltwater streams called outwash. Retreating glaciers leave behind material called drift composed of silt, clay, sand, gravel, and boulders. Areas with diagonal hatching were glaciated previously. Typical terrain of The Driftless Area as viewed from Wildcat Mountain State Park in Vernon County, Wisconsin Glacial map of the Great Lakes region the dark area near left center was not covered by drift. Geologic origin 1911 Map showing extent of the Driftless Area as well as the Driftless region in Minnesota and Iowa. The region has elevations ranging from 603 to 1,719 feet (184 to 524 m) at Blue Mound State Park, and together with the Driftless-like region, covers 24,000 square miles (62,200 km 2). The steep riverine landscape of both the Driftless Area proper and the surrounding Driftless-like region are the result of early glacial advances that forced preglacial rivers that flowed into the Great Lakes southward, causing them to carve a gorge across bedrock cuestas, thereby forming the modern incised upper Mississippi River valley.
Ecologically, the Driftless Area's flora and fauna are more closely related to those of the Great Lakes region and New England than those of the broader Midwest and central Plains regions. Its landscape is characterized by steep hills, forested ridges, deeply carved river valleys, and karst geology with spring-fed waterfalls and cold-water trout streams. Never covered by ice during the last ice age, the area lacks the characteristic glacial deposits known as drift. The Driftless Area takes up a large portion of the Upper Midwest forest–savanna transition. The Driftless Area is a USDA Level III Ecoregion: Ecoregion 52. Topographic map Autumn in the Driftless Area of Cross Plains, WisconsinĤ3☃0′N 91☀0′W / 43.5°N 91°W / 43.5 -91The Driftless Area, also known as Bluff Country, the Blufflands, the Paleozoic Plateau, and the Coulee Region, is a topographical and cultural region in the Midwestern United States that comprises southwestern Wisconsin, southeastern Minnesota, northeastern Iowa, and the extreme northwestern corner of Illinois.
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