The Portage Lake Volcanics (Middle Keweenawan) on Isle Royale, Michigan,
Huber, N. King(Norman King),1926-
United States.National Park Service.
Washington, U.S. Govt. Print. Off.,
1973.
"Prepared in cooperation with the National Park Service."
Bibliography: p. C30-C32.
Volcanic ash, tuff, etc.
Geology, Stratigraphic
Geology