http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Preliminary geologic and tectonic maps of Oregon east of the 121st meridian
Department of Geology and Mineral Industries.
compiled by George W. Walker ; prepared [by] the Department of the Interior, United States Geological Survey in cooperation with the Oregon Department of Geology and Mineral Industries.
Explanation for both maps given on sheet 2.
Miscellaneous field studies map / United States Geological Survey ; MF-495