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
Fox River (Illinois River tributary) area. From the chain, the river flows generally southward for , until it joins the Illinois River at Ottawa. Illinois towns and communities that are on the Fox River include (from north to south): Fox Lake, Johnsburg, McHenry, Holiday Hills, Island Lake, Burtons Bridge, Port Barrington, Cary, Fox River Grove, Algonquin, Carpentersville, West Dundee, East Dundee, Elgin, South Elgin, St. Charles, Geneva, Batavia, North Aurora, Aurora, Montgomery, Oswego, Yorkville, Plano, Millington, Sheridan and Ottawa. Collectively, the area surrounding the Fox River is known as the Fox Valley. Around 1 million people live in this area. Native American tribes that lived