Columbia subject headings:
Crystalline rocks.
Geology, Stratigraphic--Precambrian.
Petrology--Superior, Lake, Region.
Radioactive waste disposal--United States.
Harvard subject headings:
Crystalline rocks--Great Lakes Region (North America)
Crystalline rocks--Superior, Lake, Region.
Geology--Great Lakes Region (North America)
Geology--Superior, Lake, Region.
Princeton subject headings: