Glacial River Warren or River Warren is the name of a prehistoric river which drained Lake Agassiz in central North America between 11,700 and 9,400 years ago. The enormous outflow from this lake carved a mighty valley now occupied by the much-smaller Minnesota River and the Upper Mississippi River. A map of the extent of Lake Agassiz Lake Agassiz was an immense lake—bigger than all of the present-day Great Lakes combined—in the center of North America, which was fed by glacial runoff at the end of the last ice age. ... World map showing North America A satellite composite image of North America. ... The Minnesota River is a tributary of the Mississippi River, approximately 332 miles (534 km) long, in the state of Minnesota in the United States. ... The Mississippi River, derived from the old Ojibwe word misi-ziibi meaning great river (gichi-ziibi big river at its headwaters), is the second-longest named river in North America, with a length of 2320 miles (3733 km) from Lake Itasca to the Gulf of Mexico. ...

Lake Agassiz was formed from the meltwaters of the Laurentide Ice Sheet during the Wisconsonian glaciation of the last ice age. Agassiz was a huge body of water, up to 600-700 feet (~200 m) deep, and at various times covering areas totaling over 110,000 square miles (~300,000 square km).^[1] Blocked by an ice sheet to the north, the lake water rose until about 11,700 years ago, when it overtopped the Big Stone Moraine, a ridge of glacial drift left by the receding glacier, at the location of Browns Valley, Minnesota. The lake's outflow was catastrophic at times,^[2] and carved a gorge through the moraine a mile (1.6 km) wide and 130 feet (~40 m) deep, which is now known as the Traverse Gap.^[3] The Laurentide ice sheet was a massive sheet of ice that covered hundreds of thousands of square miles, including most of Canada and a large portion of the northern United States, between ~ 90,000 and ~ 18,000 years before the present day. ... This article or section should be merged with Wisconsin glaciation The Wisconsinian was the last major advance of continental glaciers in North America. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... Moraine at Mono Lake, California, United States Moraines clearly seen on a side glacier of the Gorner Glacier, Zermatt, Switzerland. ... Browns Valley is a city located in Traverse County, Minnesota. ...

From the gap issued the Glacial River Warren. From its inception until final abandonment of Agassiz' southern outlet, this stream drained the meltwater of that lake to the Mississippi valley. The drainage was not however continuous, as Lake Agassiz periodically had other outlets. The Laurentide ice sheet retreated and advanced with climatic variations and these changes in the ice sheet in turn contributed to isostatic adjustments in the level of the land over which the watercourses ran. These changes in turn uncovered or blocked the lake's outlets to the sea.^[4] Isostasy is a term used in Geology to refer to the state of gravitational equilibrium between the Earths lithosphere and asthenosphere such that the tectonic plates float at an elevation which depends on their thickness and density. ...

But while active this turbulent stream cut and eroded a valley up to five miles (8 km) wide and 250 feet (80 m) deep.^[5] This valley starts at Traverse Gap near Browns Valley, Minnesota, goes southeast to Mankato, then turns northeast to the Twin Cities where River Warren was joined by the comparatively small Mississippi. River Warren undercut the smaller river at the site of Fort Snelling and created falls, which have since migrated upstream on the Mississippi and formed Minnehaha Falls and the Falls of St. Anthony in Minneapolis. From Fort Snelling the valley continues northeast to present-day Saint Paul and then turns southeast to Prescott, Wisconsin, where it is joined by the St. Croix River, itself once the outlet of another proglacial lake, Glacial Lake Duluth which occupied the western part of Lake Superior. From its confluence with the St. Croix the valley continues southeast where the border between Minnesota and Wisconsin is now located. River Warren's effects include the creation of bluffs along the valleys of the Minnesota and Mississippi, and contributed to the formation of Lake Pepin.^[6] Browns Valley is a city located in Traverse County, Minnesota. ... Mankato is an acoustic/vocal duo from Wheaton, IL. Influenced by talent such as Kepano Green, Dashboard Confessional, Damien Rice, Coldplay, Muse, Delirious, Ben Folds, and of course The Beatles. ... This article or section does not adequately cite its references or sources. ... This article does not adequately cite its references or sources. ... Fort Snelling is a former military fortification located at the confluence of the Minnesota and Mississippi Rivers in Hennepin County, Minnesota. ... Minnehaha Falls Minnehaha Creek is a short tributary of the Mississippi River located in Hennepin County, Minnesota that extends from Lake Minnetonka in the west and flows east for 22 miles (35 km). ... Aerial view of Saint Anthony Falls with the upper dam Saint Anthony Falls, or the Falls of Saint Anthony, located near downtown Minneapolis, Minnesota, was the only waterfall on the Mississippi River until it was replaced by a series of dams in the 1950s and 1960s. ... This article is about the city in Minnesota. ... Location in Ramsey County and the state of Minnesota. ... Aerial view of the city Prescott is a city in Pierce County, Wisconsin at the confluence of the St. ... The St. ... In geology, a proglacial lake is a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or one formed by meltwater trapped against a ice sheet due to isostatic depression of the crust around the ice. ... Glacial Lake Duluth Glacial Lake Duluth was a lake that formed in the vicinity of Lake Superior as the Laurentian Glacier retreated. ... Lake Superior, bounded by Ontario and Minnesota to the north and Wisconsin and Michigan to the south, is the largest of North Americas Great Lakes. ... Official language(s) None Capital Madison Largest city Milwaukee Area  Ranked 23rd  - Total 65,498 sq mi (169,790 km²)  - Width 260 miles (420 km)  - Length 310 miles (500 km)  - % water 17  - Latitude 42°30N to 47°3N  - Longitude 86°49W to 92°54W Population  Ranked... Lake Pepin is a widening of the Mississippi River on the border between Minnesota and Wisconsin. ...

By about 9400 years ago, the ice sheet finally retreated sufficiently far to the north that Lake Agassiz permanently took another outlet and receded below the level of Traverse Gap. River Warren then ceased to run.^[7] The Lake Agassiz area watershed now feeds the Red River of the North which flows north, ultimately to Hudson Bay. The River Warren's upper valley in the Traverse Gap is now occupied by the tiny Little Minnesota River, which flows into Big Stone Lake and the Minnesota River, which follows the greater river's ancient bed to its confluence with the Mississippi River. These streams occupy only a small cross-section of River Warren's riverbed.^[8] This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... See also the Red River disambiguation page. ... Hudson Bay, Canada. ... The Little Minnesota River is a tributary of the Minnesota River in northeastern South Dakota and west-central Minnesota in the United States. ... Big Stone Lake is a long, narrow freshwater lake and reservoir forming the border between western Minnesota and northeastern South Dakota. ...

References

Notes

Sources