A city-sized meteorite impact crater lies hidden beneath this small Iowa town
In short: Beneath the streets of Decorah, Iowa, sits a massive, four-mile-wide crater formed by a space rock the size of a city block. Discovered only recently, this ancient scar remains largely buried, yet it provides scientists with a unique window into the prehistoric oceans that once covered the American Midwest.
Roughly 470 million years ago, a massive celestial object struck the region now known as Decorah. This event supports the theory that a larger space rock fragmented, bombarding Earth during a period when early life was rapidly diversifying in the planet's oceans. The resulting impact created a crater nearly four miles in diameter, which remained hidden for eons because almost none of the structure is visible above the surface.
The crater was identified by researchers like Bevan French, a prominent expert in impact sites and a scientist associated with the National Museum of Natural History. The depression was preserved because it was eventually filled by a distinct type of shale. This sediment accumulated after an ancient seaway flooded the crater, trapping a variety of unusual marine creatures that were subsequently fossilized. Among these is the creature Pentecopterus decorahensis, which was named after the city.
Beyond its geological significance, Decorah serves as a cultural and economic hub in the Driftless Area of northeastern Iowa. Originally a site for Ho-Chunk villages until their forced removal in 1848, the town was settled by European-Americans in 1849. Today, it is recognized for its strong Norwegian-American heritage, hosting the Vesterheim Norwegian-American Museum and the annual Nordic Fest. With a population of 7,587 as of the 2020 census, the city balances its deep geological history with its role as a center for education, agriculture, and cultural preservation.
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- Summary by Intellect · source: Decorah, Iowa
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