Starting around late February and lasting three to four weeks, a helicopter towing a large hoop from a cable will begin making low-level flights over southern Wisconsin between Grant and Kenosha counties.

The low-flying helicopter will collect and record geophysical measurements as part of multiple U.S. Geological Survey projects to improve below-ground geologic maps.

In southwest Wisconsin, USGS scientists working with the Wisconsin Geological and Natural History Survey and funding support from Wisconsin USDA - Natural Resources Conservation Service will use data collected during the survey to determine bedrock depth and glacial sediments in parts of Grant, Iowa, Lafayette and Green counties.

In southeast Wisconsin, scientists will collect data along and adjacent to the Fox River to improve understanding of shallow aquifers that control groundwater and surface water movement as part of a larger USGS study of the Illinois River Basin.  

The helicopter will fly along pre-planned flight paths relatively low to the ground, hundreds of feet above the surface. A sensor that resembles a large hula-hoop will be towed beneath the helicopter to measure tiny electromagnetic signals that can be used to map features below Earth’s surface. Most survey flight lines will be separated by a half mile to five miles, so the helicopter system will only be visible from any particular location for a short period of time.

The USGS is contracting with SkyTEM ApS, a specialty airborne geophysical company, to conduct the survey. The helicopter will be operated by experienced pilots from Sinton Helicopters who are specially trained for the low-level flying required for geophysical surveys. The company works with the FAA to ensure flights are safe and in accordance with U.S. law.

This study expands similar work done last year in parts of northeast Wisconsin to improve maps of shallow bedrock depth using the same helicopter instruments. USGS scientists recently released data and maps from last year’s study.