2-50. Secrets of the Driftless Area

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While it may sound like part of an old West town where drifters were discouraged from visiting, the term “driftless” actually means an area without glacial debris, or drift. This is the rocks, silt, clay, stones, etc. left behind when the glaciers retreated from North America a bit over 10,000 years ago.

Starting nearly 100,000 years ago, the Earth cooled and massive glaciers, some miles thick, covered the northern parts of North America. These massive flows of ice destroyed everything in their path, completely rearranging the topography. Mountains were leveled, valleys were carved, and when the ice melted, this newly revealed landscape became what we now know as Canada and the Northern United States.

In the Midwest, specifically parts of Wisconsin, Illinois, Minnesota and Iowa, the glaciers went around large, low mountains known as “domes,” and left the land south of them untouched. These are now known as the driftless area, and they’re unique, as the land there hasn’t been drastically altered for at least 500,000 years.

While the glaciers didn’t reach these areas, water from their melting did, and caves, blind valleys, and disappearing streams are common. It’s some of the most beautiful land in the country, and it has secrets.

Algific talus slopes, with algific meaning “cold producing” are only found here. They’re a form of natural air conditioner, where warm air is pulled into a sinkhole, through cold and even ice-filled caves, and then forced out onto the slope through another opening. This chilled air can reduce the temperature by as much as 30 degrees on a hot summer’s day.

Because of this, the ecosystem there resembles Northern Canada more than the Midwestern US. Local Forests favor ancient lineages of plants such as ferns, liverworts and yew, with relatively few hardwoods. Some plants and snails here are either extremely rare or only found in this area. Most algific talus slope land is off limits to the public due to the fragility of the ecosystem.

Another secret of the driftless area is its many effigy mounds. These are hundreds of piles of earth up to 150 feet high built by people 1000 years ago. About 15% of them have an earthen sculpture of a larger-than-life animal on the top. Many different mammals, birds and reptiles are featured. With one exception in Ohio, the style of these mounds is unique to the driftless area. No one living today knows exactly what they were for.

So, if you’re in the Midwest and you’d like to walk on land that may have once been the home of a woolly mammoth or a pre-Columbian family, the driftless area of the rural Midwest has that for you.

National Park Service photo of Bear Mound

National Park Service photo of Bear Mound

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