From University of Iowa via geology.com:
Recent airborne geophysical surveys near Decorah, Iowa are providing an
unprecedented look at a 470- million-year-old meteorite crater concealed
beneath bedrock and sediments.
The aerial surveys, a collaboration of the U.S. Geological Survey with
the Iowa and Minnesota Geological Surveys, were conducted in the last 60
days to map geologic structures and assess the mineral and water
resources of the region.
“Capturing images of an ancient meteorite impact was a huge bonus,” said
Dr. Paul Bedrosian, a USGS geophysicist in Denver who is leading the
effort to model the recently acquired geophysical data. “These findings
highlight the range of applications that these geophysical methods can
address.”
