USGS Data Series 321: Illinois, Indiana, and Ohio Magnetic and Gravity Maps and Data: A Website for Distribution of Data

Illinois, Indiana, and Ohio Aeromagnetic Anomaly Maps - Higher Resolution

This individual aeromagnetic residual anomaly grid/map was generated using the most representative grid interval for the flight-line spacing of the survey and maintain the original flight altitude of the individual surveys. It was then regridded to the 500-m (1,640-ft) interval and continued to the 305-m (1,000-ft) above-ground flight altitude used in the States compilation.

The map is displayed with an illumination from the northeast. The image was generated with a resolution to fit the screen and not with regard to original grid interval. The grid for the map is in Geosoft Oasis montaj binary format (downloadable free software for conversions to other grid formats at www.geosoft.com) and available in the data directory. A 'README.txt' file located there further defines the format.

For a full description of survey specifications see "Illinois, Indiana, and Ohio Magnetic Data Index Maps" page.

Wabash Valley (4163) survey gridded at 100 m.