The Geology of Southeastern Minnesota

The Geology of Southeastern Minnesota. . , The face of Minnesota has undergone many changes over the centuries as a result of the forces of nature. Its present appearance is the result of modification over four glacial periods that have created the landscape you see along the roadways. These glaciers were masses of moving ice and snow that covered the surface of Minnesota at various times during the past 2 million years. The last, called the Wisconsin, melted away some 10,000 years ago. , As you travel east and descend into the Mississippi River valley, you will notice that the terrain changes. This corner of the state is the driftless area, an area that was not covered by the last glacier. Here you will find no natural lakes, and the deep valleys and towering bluffs are the end result of the erosion caused by the melt-waters of the glacier, located to the north and west. The extreme southeastern corner may never have been glaciated, just like the southwestern corner of Wisconsin. , As you travel through the valley you will notice in the roadcuts and bluffs, exposures of limestone, sandstone and dolomite. These rock formations were deposited by oceans which have covered the area several times in the past. the most recent being some 70 million years ago. These types of stone are easily eroded by qroundwater and there are numerous sinkholes and even caves, to be found in the area. Fillmore County, south of here, has two extensive caves, Niagara and Mystery, which have been explored and are open to the public. , The rich soil, and the natural beauty of the area attracted first settlers, and later tourists. Numerous trails have been developed for use by both residents and visitors, allowing them the opportunity to enjoy and explore the geology of the area.