Would You Guess America’s Largest Asteroid Crater is (Sort of) in Iowa?
Originally said to have been the asteroid impact that killed off the dinosaurs, this crater near Manson was created by a meteorite impact close to 74 million years ago.
If you're a history buff, you know that the actual mass extinction of dinosaurs took place roughly 65 million years ago, so the Manson meteor is out of the question. That's not to say this asteroid impact didn't have a significant effect on Iowa and the surrounding Midwest.
At the time of the collision -- the Cretaceous Period -- the earth was much warmer, and western Iowa was largely covered by an inland sea. The body of water contained species that we know of today, such as the Plesiosaur.
Upon entrance to our atmosphere, the conglomeration of rock was traveling at 45,000 miles per hour, and once it made landfall the result was deadly. Crashing into our planet and releasing the same amount of energy as 1.1 million megatons of TNT, "all life was destroyed in a circle with a 650-mile radius, extending from what is now Denver to Detroit and Winnipeg, Canada, to Dallas," says shl.uiowa.edu. "The meteorite formed a crater that remains buried under the landscape, stretching 24 miles wide through four counties – Calhoun, Pocahontas, Humboldt and Webster."
As stated in the previous quote, the crater is buried under the Iowa landscape, having been filled with sediment in the following millions of years. Due to the filling of the crater, it wasn't discovered until the 1930s during an oil-drilling expedition.
Despite the lack of a visible crater, Manson celebrates its Greater Crater Days the last full weekend in June.
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