|This dataset was digitized by the U.S. Geological Survey EROS Data Center and U.S. Geological Survey Spokane Field Office for input into an Arc/Info geographic information systsem (GIS) The digital geologic map database can be queried in many ways to pro
|Harrison, Jack E.; Griggs, A. B.; Wells, J. D.; Kelley, W. N.; and Derkey, Pamela D.
|U.S. Geological Survey Miscellaneous Investigations Series Map I-1509-A
Aeromagnetic anomaly grid cells are given in nanoteslas, and values are expected to range from -400 to 400. Gravity anomaly grid cells are given in milligals. Values are expected to range from -64 to 0 for complete Bouguer anomaly and from -40 to 20 for isostatic anomaly. Grids are provided in Geosoft's binary (proprietary) format with georeference information stored in an ancillary file and as TIFF images with georeference transformation information stored in an ancillary .tfw "world" file.