Geology of the Kankakee River System in Kankakee County, Illinois

The Kankakee River flows westward from Indiana to Illinois. The headwaters are near South Bend, Indiana, and the mouth is the con- fluence with the Des Plaines River where those two rivers become the Illinois River. In work beginning in the late nineteenth century and essentially completed by 19183 almost all of the main channel of the Kankakee River in Indiana was channelized. Today that channel is a manmade ditch, extending straight for many miles between small bends. In Indiana, all of the natural meanders were removed. In Illinois, a very small dam exists at Momence and a larger dam exists at Kankakee, but most of the river remains a naturally meandering stream. The geologic framework of the Kankakee River as we know it today was established at the time of the melting of the last continental glaciers. That melting occurred during the approximate interval from 16,000 to 13,000 years ago, the latter portion of the Woodfordian Substage of the Wisconsinan Stage. From the time of the glacial melting to the present day, the Kankakee River has carried great quantities of sand westward. Most of the landscape adjacent to the main stem of the Kankakee River in Indiana is sand. The geology of the Illinois portion of the basin is more complex; in Kankakee County, Illinois , it includes silty and clayey glacial tills, silty and clayey lacustrine sediment, exposed bedrock, and sand. From the Illinois-Indiana state line downstream to near the city of Momence, the river channel is underlain by thick deposits of sand overlying bedrock. In the several miles of river channel adjacent to Momence and a 2-mile reach upstream of Aroma Park, the Kankakee River is flowing over bedrock. In the area between the cities of Momence and Aroma Park, the channel contains a series of massive sand bars, up to 1 or 2 meters thick, overlying bedrock. The upper (eastern) end of Six Mile Pool contains thick sand deposits. In the lower end (western) of Six Mile Pool, near the city of Kankakee, the main channel is underlain by bedrock although the insides of the meanders have sand bars. This report was submitted by the Illinois State Geological Survey in fulfillment of Contract 20.121 between the Illinois Institute of Natural Resources and the University of Illinois. It is one of a series of studies of the hydrology and sediment transport (Illinois State Water Survey) , the biology (Illinois Natural History Survey), and the geology (this report) of the Kankakee River system in Illinois