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St. Croix Stagnation Moraines

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About the St. Croix Stagnation Moraines

The St. Croix Stagnation Moraines, referred to in some documents as the St. Croix Pitted Stagnation Moraines, is an area of stagnation moraines and ground moraines located in eastern Minnesota and nortwestern Wisconsin, extending roughly from Minneapolis northeast well into Wisconsin.

This region consists mostly of irregular, pitted and hummocky terrain, with numerous small lakes throughout. On a broader scale it ranges from flat to rolling, with a few steep slopes where terminal moraines are found. Surface soils are mostly formed on sandy-loamy glacial till, but underneath this tend to be coarser sand and gravel that forms more acidic soils where it is exposed.

This region was originally mostly forested, with openings onto oak savanna on the drier sites. Forested sites had a mix of aspen / birch / and pine, oak-maple forests, and sugar maple / birch / pine forests.

Nowadays, the southwestern portion of this region has been intensely urbanized, including much of the city of Minneapolis as well as its suburbs. Terrain has been extensively leveled in the city and its denser suburbs, erasing the characteristic shape of the terrain, although numerous small lakes still exist within the city limits. However, many of the lower-density, outer suburbs still have the characteristic hummocky terrain. Farther northeast, the region is largely rural, and there is a mix of agriculture and forest, with generally more agriculture than areas to the northwest, but less than areas to the southeast. Relative to areas to the southeast, there is less cropland; in places the only agricultural use is pastureland. There is significant forest cover, and it is a mix of small woodlots throughout, with larger tracts of forest on steeper terrain, and occasionally on low, swampy areas as well.

Particularly in the northeast of this region, in Wisconsin, some of the streams and rivers here have been dammed, increasing the size of some of the lakes beyond what originally occurred here; Wapogasset lake and attached Bear Lake, and Cedar lake are an example of such damming. There is often residential and recreational development around these artificial lakes, and their borders generally lack the wetlands that naturally occurred along the margins of lakes throughout this region. There are, however, many lakes that are unaltered to less-altered, and still have extensive wetlands on their margins. The Willow River has also been dammed in this region, at the New Willow River Dam.

There is some public protected land here, much of which is managed for wildlife, with hunting in mind. Such areas include various named Waterfowl Production Areas, including Beyl, Prairie Flats-North, Bass Lake, and others. Willow River State Park has some protected areas of bottomlands along the Willow River, although this area has been severely altered from its original state by the damming there. Along the Mississippi, a larger, more intact area of bottomlands exists at St. Croix Islands State Wildlife Area.

This region is bordered to the southeast by two regions that have richer soils and more agriculture, and generally lacks the hummocky terrain and lakes found here: in the southwest, the border is with the Lower St. Croix and Vermillion Valleys, and in the northeast, the border is with the Central Wisconsin Undulating Till Plain. To the west, this region is bordered by the Big Woods. The southwest part of this region is bordered to the northwest by the Anoka Sand Plain and Mississippi Valley Outwash. Northeast of that there is a small border to the northwest with the McGrath Till Plain and Drumlins, and farther northeast, in Wisconsin, this region is bordered to the northwest and north by the St. Croix Pine Barrens. In the far northeast, this region transitions to the Chequamegon Moraines and Outwash Plain, another area with hummocky terrain, but a colder climate, and a greater portion of forest cover; this border rather arbitrary and not well-defined.

References

1. Albert, Dennis A. "Regional landscape ecosystems of Michigan, Minnesota, and Wisconsin: a working map and classification.", General Technical Report NC-178, U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station, St. Paul, MN (1995) Web.

2. Denis White "Ecological Regions of Minnesota: Level III and IV maps and descriptions", (2020) Web.