Big Muddy River Southern Illinois with "loess", fine grained, wind born deposits. At the edge of the floodplain, dunes, called "loess hills", formed. The Pine Hills are loess hills standing several hundred feet above the floodplain. Prior to the construction of Rend Lake, much of the ancient lake bed was swamp: a forested area that was covered by water through most of the winter, and during wet summers. When the Big Muddy flooded, the water covered the flat bottom of the ancient lake bed for miles either direction from the meandering channel. The upper reaches of the Big Muddy are near Dix, Illinois.
Big Sandy Creek (Illinois) two streams combine shortly before discharging into the Illinois River opposite the hamlet of Montezuma, Illinois. Sand discharged by the alluvial creeks may have helped form McEvers Island, a silt island in the Illinois River just below the mouth of the creek. Big Sandy Creek (Illinois) Big Sandy Creek, often called the "Big Branch", is a tributary of the Illinois River in central Illinois. It drains a large portion of southwestern Morgan County and southern Scott County. The drainage of Big Sandy Creek includes Lake Jacksonville and the county seat of Scott County, Winchester, Illinois. Most of the Big Sandy