MONTANA'S GEOLOGIC MAPPING PROGRAM -- THE ROLE OF STATEMAP

A high priority of Montana Bureau of Mines and Geology’s (MBMG) geologic mapping program is completion of a 1:100,000-scale bedrock geologic base, in digital form, for the State. Since the passage of the National Geologic Mapping Act in 1992, the STATEMAP element of the U. S. Geological Survey’s National Cooperative Geologic Mapping Program has been the primary source of funding for MBMG’s work. In 1996, MBMG initiated map completions in GIS, and began bringing older maps into digital form. Prioritization of all STATEMAP map areas is established by MBMG’s STATEMAP Advisory Committee representing State and Federal agencies, industry, and academia. To date, 53 of 94 quadrangle maps have been completed under STATEMAP, and digital coverage is available for 54% of the state at the 1:100,000 scale.

Larger-scale maps (1:48,000) for critical areas of the State, including principal metropolitan areas, transportation corridors, and the intermontane valleys of western Montana are also underway. To date, maps are complete for the Metropolitan Billings area, Bitterroot Valley, and part of the Gallatin (Bozeman) Valley. FY 2002 STATEMAP work will complete the Gallatin Valley and initiate the Upper Yellowstone (Paradise Valley) areas. The 1:24,000-scale base is more familiar to lay users than a metric base.

A new Geologic Map of Montana at the 1:500,000 scale is progressing simultaneously with the 1:100,000-scale quadrangle map production. Each new quadrangle becomes a part of the developing data base that will become the new state map. Parallel efforts include continuous edge matching to produce a seamless coverage, and continuous development of a standard list of stratigraphic names and letter symbols.

At MBMG’s web site, http://www.mbmg.mtech.edu, one may view the periodically updated status of the mapping program, the availability of digital data, and linkage to the Publications Office for ordering maps.