Weather.com - 3/6/13, David Pitt

DES MOINES, Iowa — Federal researchers confirmed Tuesday that the city Decorah sits atop a 3 ½-mile wide hole that formed 470 million years ago when a meteorite hit the area, one of just 180 or so known impact craters on earth.

Scientists with the U.S. Geological Survey said aerial gravity and electrical magnetic surveys of the area confirm the work of geologists that shows a buried crater concealed beneath bedrock and sediment.

For more info on this story click: Meteorite Crater [2]