Complex sentence: There are two additional beaches formed when the Des Plaines outlet was abandoned for other outlets to the north and east: the Calumet Shoreline, about to above the current lake, and the Tolleston Beach to above Lake Michigan.
Split into simpler sentences: There are two additional beaches formed when the Des Plaines outlet was abandoned for other outlets to the north and east. The Calumet Shoreline about to above the current lake, and the Tolleston Beach to above Lake Michigan.