Marginal legend and cross sections. "Base map compiled by the U. S. Geological Survey from U. S. Geological Survey atlas sheets, Land Office records, compilations by State Geological Surveys, official maps of Canada and other data."
Geological Survey (U.S.)
Van Hise, Charles Richard, 1857-1918; Leith, Charles Kenneth, 1875-1956
University of Minnesota Libraries, John R. Borchert Map Library.