 The Duluth and Beaver Bay complexes lie south of this line.Near Lake Superior these intrusive formations intermingle in a complex mosaic with the rocks of the associated North Shore Volcanics, which also are relics of the Midcontinent rifting event.The Duluth and Beaver Bay Complexes extend a short distance under Lake Superior south of the present lakeshore, but in most places along and near that shore their southern reaches are overlain by the North Shore Volcanic Group.