The Valparaiso Moraine is a recessional moraine that forms an immense U around the southern Lake Michigan basin in North America. It is a band of hilly terrain composed of glacial till and sand. The Valparaiso Moraine defines part of the continental divide known as the Saint Lawrence River Divide, bounding the Great Lakes Basin. It begins near the border of Wisconsin and Illinois and extends south through Lake, McHenry, Cook, DuPage and Will counties in Illinois, and then turns southeast, going through northwestern Indiana. From this point, the moraine curves northeast through Lake, Porter, and LaPorte counties of Indiana into Michigan. It continues into Michigan as far as Montcalm County.