During the past 75,000 years, glaciers have advanced and retreated across Minnesota several times. The last ice sheet to retreated northward about 12,000 years ago. Its meltwater formed the immense Glacial Lake Agassiz. Larger than any body of fresh water known in modern times, Lake Agassiz covered northwestern Minnesota, portions of North Dakota, Ontario, Saskatchewan, and much of present day Manitoba.
The southern outlet for this huge body of water was located near Lake Traverse and Brown's Valley, MN. Called River Warren, water from Lake Agassiz cut what became known as the Minnesota River Valley and had a great influence on the topography of the Minneapolis/St. Paul metropolitan area.
An enormous waterfall, Glacial River Warren Falls, was originally located near what was to become downtown Saint Paul. The huge rush of water coming down the channel of the River Warren eroded out the glacial debris that filled the valley and began undermining the limestone cap rock of the river bed. Huge boulders of limestone caprock, no longer supported by the soft, easily-eroded St. Peter's sandstone that supported it, broke off moving the lip of the waterfall upstream. The waterfall moved incrementally upstream, sometimes by several feet each year.
As the falls reached the what was to become the confluence of the Minnesota and Mississippi River, it broke into two parts with one falls moving up the Minnesota River and the other moving up the Mississippi River. The falls that moved up the Minnesota evolved into rapids and disappeared. The falls that moved up the Mississippi River became what is now known as St. Anthony Falls, named by Father Louis Hennepin.
River Warren Falls is the ancestor of St. Anthony Falls, Hidden Falls, and Minnehaha Falls, among others. Today there is still evidence of the River Warren Falls’ migration up the river valley. Slabs of the limestone cap rock, once the edge of the falls, can be seen lining the banks of the river. The presence of sandy terraces along the river bluffs also show the earlier flood plains.
Activities: The Mississippi River Gorge contains many city and regional parks with a wide variety of activities.
Hours: Varies by park.
More Information: Visit Great River or visit the Geology Information Page in the features section of the Mississippi National River and Recreation Area Website. Chapter 1 of the Historic Resource Study is an excellent source of information about the River Warren Falls.
Last updated: February 28, 2020