The crater lies on the south end of Inver Grove Heights, near
the Mississippi River.

(Fox News) – University of Minnesota researchers have discovered
an ancient crater lying 350 feet below a Mississippi River suburb.

A team of scientists at the Minnesota Geological Survey (MGS) –
part of the university’s College of Science and Engineering’s
School of Earth and Environmental Sciences – discovered the
crater while updating a geologic map of Dakota County; the
county borders Minneapolis and St. Paul. 

For reference, researchers say they believe this crater would be
11 times the size of the famous Meteor Crater in Arizona. They
say it appears the massive meteor struck the earth around 490
million years ago, putting it near the end of the Cambrian period.