Big Muddy River The Big Muddy was not covered by the Wisconsin Glacier, about 70,000 to 10,000 years before present. However, during the melting of that glacier, the level of the Mississippi River was much higher. Water backed up into the Big Muddy Basin, forming a lake much like the artificial Rend Lake but covering a larger area. The ancient lake silted in, forming a flat bottom. After the melting of the Wisconsinan glacier, the level of the Mississippi dropped, allowing the lake to drain. A new channel formed within the old lake bed. This channel meandered in the flat bottom of the
River Grove, Illinois River Grove, Illinois River Grove is a village in Cook County, Illinois, United States. The population was 10,227 at the 2010 census. River Grove is located at (41.925830, -87.840135). According to the 2010 census, River Grove has a total area of , all land. Just as nearby Elmwood Park and Oak Park are named after their historic elm and oak trees, River Grove gets its two-part name first from the community's shallow muddy plains river, and second from the majestic groves of American ash trees lining shore of the (Aux) Des Planes River "Bottomland." Credit goes to the village's early