Contributing Organization: U.S. Geological Survey
EROS Data Center User Services
Sioux Falls, SD 57198

Summary: A 2 kilometer Bouguer gravity anomaly grid for the Idaho batholith study area. Number of columns is 331 and number of rows is 285. The order of the data is from the lower left to the right and then up one row.

BOUGUER GRAVITY GRID

The complete Bouguer gravity grid was complied using data obtained from 32,152 stations. These data were extracted from the gravity data base of the State of Idaho (Bankey and others, 1985) and include additional data from U.S. Geological Survey (USGS) gravity surveys, the Defense Mapping Agency gravity data base, and data collected for university theses and dissertations. Observed gravity data relative to the IGSN-71 datum (International Association of Geodesy, 1974) were reduced to the Bouguer anomaly, using the 1967 gravity formula (International Association of Geodesy, 1971) and a reduction density of 2.67 g/cm^^3. Standard USGS reduction equations and related expansions are given in Cordell and others (1982). Terrain corrections were calculated radially outward from each station to a distance of 167 km using a method developed by Plouff (1977). The data were converted to a 2-km grid using a computer program developed by Webring (1981) based on minimum curvature (Briggs, 1974).

CAVEAT: Caution is recommended when using these data. This data increment was provided to NGDC with minimal documentation. NGDC will continue to seek improved documentation as part of a routine and on-going data rescue effort.

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