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On-line Gravity and Magnetic Maps of Kansas

This page is based on Open-file Rept. 96-51 by Joseph M. Kruger

County Gravity and Magnetics || State Gravity || State Magnetics


62,606 gravity-station measurements were taken by the KGS. In eastern Kansas, the original data are spaced approximately 1 mile east-west by 1 mile north-south. In western Kansas, the data are spaced 2 miles apart north-south and 1 mile east-west. The data were corrected for tidal changes and machine drift using base stations and software written at the KGS. Topographic maps were used for location and elevation information.

After reduction to Bouguer anomoly values, the data were gridded with a two-pass, 8-directional gridding algorithm. A second-order polynomial surface was calculated to remove a regional westward decrease in gravity values caused in part by thickening of the crust. The resulting second-order residual grid, previously used in several KGS open-file reports, was brought into ER Mapper software for analysis.

These colored images are displayed with apparent relief created by vertical illumination. Blues represent lowest residual Bouguer gravity values; reds represent highest residual Bouguer gravity values. Steeper gradients are indicated by darker shading.


Approximately 45,000 line-miles of digitally recorded aeromagnetic data were acquired at 1/4-mile intervals along east-west flight lines spaced 2 miles apart across Kansas. North-south tie lines were flown approximately 20 miles apart. The data were leveled using the tie lines and a least-squares algorithm. Three elevations were used in flying over Kansas. One jump occurs in the middle of the state and shows up as a north-south artifact in the maps. The other elevation change, in western Kansas, is less apparent.

The grid was reduced to the pole using inclination of 65 degrees and declination of 7 degrees. Reduction to the pole was performed to improve the resolution and shape of anomalies. In addition, this process roughly centers anomalies over their causative bodies. Grids used in published and open-file KGS maps were brought into ER Mapper software to create these images.

These colored images are displayed with apparent relief created by vertical illumination. Blues represent lowest magnetic values; reds represent highest magnetic values. Steeper gradients are indicated by darker shading.

Combination maps

The following maps display a combination of gravity and magnetic data on one map. In some cases, gravity data is represented by color and the magnetic information is represented by the apparent relief shading. Other maps with the attributes reversed are also shown.

References and related publications

The following maps represent the data used in the images presented here.
M-41D Aeromagnetic Map of Kansas, Reduced to a Horizontal Plane and Reduced to the Pole, by J. Xia, R. Miller, and D. W. Steeples, scale 1:1,000,000, 1995
M-41E Residual Bouguer Gravity Map of Kansas, the Second-order Regional Trend Removed, by J. Xia, R. Miller, D. W. Steeples, and D. Adkins-Heljeson, scale 1:1,000,000, 1995

Please see the References Page for additional publications or open-file reports concerning gravity and magnetics data of Kansas.

Kansas Geological Survey, Petroleum Research Section
Updated August 25, 1997
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