Ancient Flood Created Potholes Still Visible Today

By Dean S. Acheson

ST. CROIX FALLS – Mother Nature had long-range plans for Interstate State Park – creating dozens of potholes in basalt bedrock in an area known today as The Dalles of the St. Croix River gorge. Some 10,000 years ago, rushing meltwater created abrasive whirlpools of sand and gravel that scouredsaucer-shaped and cylindrical depressions into the hard rock surfaces of terraces carved by the Glacial St.Croix River.

Among the potholes of various sizes and shapes is one nearly a perfect pothole – four and half feet wide and 18 feet deep. The Minnesota side of Interstate Park contains more than 80 of these glacial potholes, the largest concentration in the world. The Pothole Trail, about 0.4 of a mile long, affords visitors views of the glacial potholes as well as awesome views of the St. Croix River gorge and a cliff information known as the “Old Man of the Dalles.”

Flush with many other geological features, the trail is one of many in the Interstate Park and Polk County itself. The park is open year-round. Daily or annual permits required.

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