Columbia subject headings:
Geology--Michigan--Gogebic County--Maps.
Iron ranges--Michigan--Gogebic County--Maps.
Maps.
Harvard subject headings:
Geology--Michigan--Gogebic County--Maps.
Gogebic County (Mich.)--Maps.
Iron ranges--Michigan--Gogebic County--Maps.
Princeton subject headings:
Geological cross sections.
Geology.
Gogebic County (Mich.)--Maps.
Maps.