Decorah Impact Crater
August 26, 2013 | EarthMagazine.org
Researchers have confirmed a 470-million-year-old impact crater near the town of Decorah, Iowa using multiple types of evidence.
Related: Google Map of Impact Sites
Huge Ancient Landslides in Colorado
April 2, 2013 | Colorado Geological Survey on Facebook
The Colorado Geological Suvey shares aerial images of two ancient landslides that consist of about 635,000,000 cubic feet of mobilized debris and cover an area of about 2.3 square miles.
Decorah Impact Structure
March 18, 2013 | University of Iowa
"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 extent of the shale, which was deposited after the impact by an ancient seaway, defines a “nice circular basin” of 5.5 km width." Quoted from the University of Iowa press release.