In case you've been noticing the low-flying helicopters around northeast Iowa, the U.S. Geological Survey is reminding the public they're still researching rock layers here.
Researchers have been conducting a survey since December to track potential mineral and water resources in Iowa and Minnesota.
Scientists have been using a low-flying helicopter to gather data.
The helicopter carries large electromagnetic instruments that hang down on cables.
The U.S. Geological Survey said none of the instruments on the aircraft pose a health risk to people or animals, and the pilots are specially trained for these purposes.
Benjamin Drenth, a geophysicist with the U.S. Geological Survey, said Tuesday he expects data collection to continue through next week.
"There haven't been any flights for a few days due to all the recent bad weather," said Drenth.
Drenth said electromagnetic measurements are being conducted during data acquisition.
He said the low-flying instruments on the helicopter have been using electromagnetic measurements to map water content of different rock layers.
"Think of it as an x-ray to image the subsurface of the Earth, except this one is very low power, less than a cell phone tower," Drenth said. "Those loops are only 30-50 meters above the ground during data acquisition, so it makes for quite a spectacle when it flies by."
Drenth said the helicopter will likely be seen flying in the Decorah area on Tuesday and Wednesday.
