A regionally-consistent and integrated geologic spatial database for the Northern Rocky Mountains of Montana, Idaho, and eastern Washington, brings together forty-three 1:100,000-to 1:250,000-scale digital geologic maps into a common database format. The regional geologic database is an ArcInfo® coverage (NR_GEO) that contains spatial data for both lines (contacts, faults, fold axes, dikes, sills, veins, garnet isograd, boundaries) and polygons (geologic units). The database represents the original content of the published maps and provides easily-used and consistent attribute content. We have also added information based on our interpretations of published reports. In particular, we have added attribute information that 1) classifies igneous rocks by age, composition, and name, and 2) allows the creation of derivative maps based on lithology. Three schemes are used to classify polygons and lines in this spatial database. The first scheme is based on the original map units defined in the source maps used to compile this database. The second approach uses the age, composition, and mode of occurrence to define igneous map units. The last approach uses the names of igneous intrusions and volcanic units to define map units. This database can be queried to address an assortment of geological questions and to produce a variety of derivative geological maps. Digital themes derived from these digital spatial geologic databases will be used by the U.S. Department of Agriculture Forest Service (USFS) for planning and research purposes and by the U.S. Geological Survey (USGS) to facilitate research and conduct mineral-resource assessments. We would like to thank Reed S. Lewis and Loudon R. Stanford with the Idaho Geological Survey and Karen Porter, Dick Berg, and Patrick Kennelly with the Montana Bureau of Mines and Geology for their cooperation in our effort to make this compilation. They worked with us to produce several new digital geologic maps and provided digital files of geologic maps and map-unit descriptions. They also answered numerous geologic questions that came up during the compilation process. Eastern Washington University students Rebecca Pitts, David Cleveland, Mike Koenig, and Richard D. West helped compile data. Ellen Burch, Information Systems Support, Inc., scanned map-unit descriptions and converted them to text format. Karen Lund and Mike O'Neill with the U.S. Geological Survey provided unpublished data for the database.

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Plates 1. Map of the Revett Formation, western Montana and northern Idaho, showing the locations of mineralized strata, diamond-drill holes, and measured sections 2. Lithologic cross sections A-B and C-D, showing stratigraphic relations and mineral zones in the Revett Formation of western Montana and northern Idaho 3. Maps showing pyrite-calcite zones in the upper and lower members of the Revett Formation, western Montana and northern Idaho, untested exploration areas, and permissive tracts for the occurrence of undiscovered Revett-subtype stratabound copper-silver deposits 1. Map of western Montana and northern Idaho, showing the locations of the study area, major faults, and stratabound copper-silver deposits in the Revett Formation .

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this program has been used the US Geological Survey, no warranty, expressed or implied, is made by the USGS as to the accuracy and functioning of the program and related program material, nor shall the fact of distribution constitute any such warranty, and no responsibility is assumed by the USGS in connection therewith.

The databases, identified as newageol, newafaul, newafold, and newadike, have been approved for release and publication by the Director of the USGS. Although these databases have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, they are released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from any authorized or unauthorized use.