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.
Muddy River (Massachusetts) of the Muddy River into the tidal Charles was much wider. It formed the eastern Brookline border with Boston and Roxbury (depending on the year), from Brookline's incorporation in 1705 until Boston's annexation of Allston–Brighton in 1873. The present form of the river and surrounding parks was created by the Emerald Necklace project, between 1880 and 1900. Under the direction of designer Frederick Law Olmsted, the project reclaimed marshland, creating sculpted and planted riverbanks. The Muddy River is mentioned by John Winthrop, in his famous "Journal of John Winthrop," as the site of an unidentified flying object in March 1638