Richard W. Ojakangas e Charles L. Matsch, Minnesota's Geology, Illus. Dan Breedy, Minneapolis, Minnesota, University of Minnesota Press, 1982, ISBN978-0-8166-0953-6.
D. A. Schneider, D. K. Holm e V. Chandler, A Superior Swath: Proterozoic Geology of the North American Midcontinent, American Geophysical Union, Fall 2006, Bibcode:2006AGUFM.T42A..06S.
Middle Proterozoic and The Mid-continent Rift (PPT), in Minnesota's Rocks and Waters, Winona State University. URL consultato il 13 aprile 2008 (archiviato dall'url originale il 18 luglio 2011).(Powerpoint presentation)
William F. Kean, Keweenawan Rift System, in Field Trips, Northern Wisconsin and Upper Michigan, University of Wisconsin-Milwaukee, 24 novembre 2000. URL consultato l'8 giugno 2007 (archiviato dall'url originale il 6 luglio 2008).