The Cenozoic History of the Upper Mississippi River

Changes in the course of the Mississippi River caused by successive glacial invasions are described. Recently discovered evidence is presented bearing on the establishment of the general course of the River between Iowa and Wisconsin and Iowa and Illinois in Nebraskan time. There are also some rock terraces believed to indicate the approximate depth to which the valley had been cut by Kansan time. The Illinoian history of the river and of Lake Calvin are reviewed. The details of the present course of the river involve the definition and partial subsequent removal of Wisconsin glacio-fluvial material