Flights to image 3D geology in Illinois, Kentucky and Indiana

Scientists with the Illinois State Geological Survey are partnering with the U.S. Geological Survey and the Geological Surveys of Kentucky and Indiana to image geology using airborne geophysical technology as part of the USGS Earth Mapping Resource Initiative (Earth MRI).

This survey is one of five large airborne geophysical campaigns being conducted across various parts of the United States. The surveys will help understand the geology over areas that may contain critical mineral deposits. The 2019-2020 Earth MRI focus is to better understand several types of rare earth element deposits that occur within the five airborne geophysical surveys. Data collected as part of all five surveys will be made public and used to guide more detailed geologic mapping at local scales. When the data analysis is complete, results will provide state-of-the-art, subsurface maps that will contribute to a wide range of 3D representations of the nation’s exposed and concealed geology.

map of flight area over Illinois Indiana and KentuckyFor this tri-state survey, the USGS is contracting with EON Geosciences and will fly over all or parts of 23 counties in southeastern Illinois, western Kentucky, and southern Indiana. Weather permitting, the survey will begin in early October and be completed in December.

Two Piper Navajo airplanes will be mounted with sensors that measure variations in the earth’s magnetic field. These variations are created by different rock types up to several miles beneath the surface. Each plane will also include sensors that measure soil and rock chemistry at the surface.

None of the instruments carried on the aircraft pose a health risk to people or animals. The aircraft will be flown by experienced pilots that are specially trained and approved for low-level flying. All flights are coordinated with the FAA to ensure flights are in accordance with U.S. law.

The survey will be flown at elevations approximately 80 to 300 meters, or about 260 to 1,000 feet, above ground in a grid pattern along east-west flight lines spaced approximately 200 meters, or 650 feet, apart. North-south flight lines will be spaced 3,000 meters, or 9,800 feet, apart. All survey flights will occur during daylight hours.

Earth MRI is a cooperative effort between the USGS, the Association of American State Geologists and other federal, state and private sector organizations to improve knowledge of the geologic framework in the U.S.


  • Dick Berg, Illinois State Geologist and director, Illinois State Geological Survey, or 217-244-2776
  • Heidi Koontz, USGS, or 303-202-4763