Several residents in the northern portion of Marshall County have reported seeing at least two small airplanes flying overhead and lower to the ground than normal. A representative with the U.S. Geological Survey (USGS) confirms it's part of a project aimed at gathering geographical data.

Heidi Koontz with the USGS said there are two Piper Navajo airplanes mounted with sensors which measure variations in the earth's magnetic field that are flying in a grid pattern collecting data. She said the east-to-west flight lines are flown about 260-1,000 feet above ground in flight lines spaced approximately 650 feet apart; north-to-south flight lines are spaced about 9,800 feet apart. All survey flights will be conducted during daylight hours.

The planes are carrying scientists with the USGS and Geological Surveys of Illinois, Kentucky and Indiana who are flying over all or parts of 23 counties in southeastern Illinois, western Kentucky and southern Indiana, with planes and crew based out of the Barkley Regional Airport in Paducah. The survey began earlier this month and, weather permitting, will be complete in Dec.

In addition to measuring the magnetic field, which helps identify rock types up to several miles beneath the earth's surface, the planes are also equipped with sensors which measure soil and rock chemistry at the surface. None of the instruments pose a health risk to people or animals, according to a press release issued by Koontz, and the pilots are specially-trained and approved for low-level flying. All flights are also coordinated with the FAA to ensure accordance with U.S. law.

This survey is one of five geophysical campaigns being conducted across the country as part of the USGS Earth Mapping Resources Initiative (Earth MRI). As part of this project, the partnering agencies are acquiring new topographic, geologic mapping and geophysical data to help locate and identify undiscovered critical mineral resources and data which could improve an understanding of those critical minerals. The focus of the project is a better understanding of several types of rare earth element deposits which occur within the five airborne geophysical surveys.

Data collected as part of the surveys will eventually be made public and used to guide more detailed geologic mapping at local scales as well as state-of-the-art subsurface maps which will contribute to a wide range of 3D representations of the nation's exposed and concealed geology.