These maps show variations in the Earth's magnetic field caused primarily by the uneven distribution of the mineral magnetite in the rocks that make up the upper part of the Earth's crust. The features and patterns of the maps reveal details of subsurface geology including the locations of buried faults, the location of magnetite-bearing rocks (which include many kinds of rocks of interest to mineral exploration), and the thickness of surficial sedimentary rocks (see examples).
The map is constructed from grids that combine information (see data processing details) collected in 41 separate aeromagnetic surveys conducted over the past 35 years. The data from these surveys are of varying quality; the southeastern region of Washington are covered only by very coarse surveys. An index plot (see plot) gives an overview of the flightline spacing of the original surveys. A data table (see table) summarizes the detailed specifications of the surveys.
HPGL plot files for the image can be downloaded (see download plots) for plotting at true scale (1:1,000,000) for the overview map.
We thank Lisle Exploration for help with the Hanford aeromagnetic data. This project was supported by the Mineral Resource, Energy Resource, and Earthquake Hazards Programs of the U.S. Geological Survey.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/of/1998/ofr-98-0241/wash_desc.html
Questions or Assistance: Contact USGS
Last modified: Wednesday, 07-Dec-2016 16:44:12 EST