A low-flying helicopter will soon be visible to residents in six counties of Montana in the greater region of Helena, the Elkhorn Mountains, Bull Mountain and the Tobacco Root Mountains. 

Scientists with the U.S. Geological Survey, Montana Bureau of Mines and Geology and Rio Tinto are partnering to image geology using airborne geophysical technology as part of the USGS Earth Mapping Resource Initiative (Earth MRI) project. 

Beginning in late May and potentially lasting until October, a helicopter under USGS contract to Sander Geophysics Ltd. and Dewberry will be flying over portions of Madison, Silver Bow, Jefferson, Broadwater, Lewis and Clark and Powell counties. 

Instruments on the helicopter will detect the Earth’s naturally occurring magnetic field and radiation. This survey is one of several large airborne geophysical campaigns being conducted across various parts of the U.S. and will help understand the geology over areas that may contain critical mineral-bearing deposit types, as well as improve mapping of potential seismic hazards. Data collected as part of this survey 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. 

Flights will occur at an altitude of 300 to 500 feet above ground and will be flown in a grid pattern with east-west lines spaced 200 meters (about 650 feet) apart and north-south lines spaced 2 kilometers (about 1.2 miles) apart. Experienced pilots, specially trained and approved for low-level flying, will operate the aircraft. All flights will occur during daylight hours and are coordinated with the Federal Aviation Administration to ensure accordance with U.S. law. The flights will be based out of Butte.