University of Minnesota Researchers Discover Ancient Meteor Crash Site Below Mississippi River Suburb

by Taylor Cunningham
(Photo by YE AUNG THU/AFP via Getty Images)

Researchers at the University of Minnesota have discovered an enormous meteor crash site that dates back nearly 500 million years under a Mississippi river suburb.

A Minnesota Geological Survey team stumbled upon the site while updating a geological map of Dakota County, which runs along the border of Minneapolis and St. Paul.

“I’ve been mapping and studying the subsurface geology of Minnesota for the last 13 years … and have not come across something as exceptional as this before,” U of M scientist Julia Steenberg said in a feature released by the University.

The discovery lies under Inver Grove Heights, which is about 9 miles southeast of St. Paul. The team believes the crater is at least 2.5 miles in diameter. To put that in perspective, that’s 11 times larger than the famous Arizona crater site that measures 0.74 miles in diameter.

“From those calculations, we estimate projectile sizes between about 150 and 600 meters, based on crater diameter estimates from 4 to 8 kilometers and [surface] rock densities of about [1.65 tons] per cubic meter,” Steenberg shared. 

In other words, the meteor that caused the crater was about “one to several football fields” in size.

The Meteor Crash Caused a ‘Pine Bend Impact’

Unfortunately, unlike the iconic Az site, people can’t see the Minnesota meteor crash from a typical vantage point. The evidence is buried 350 feet below ground, which means only scientists can get a good look at it. But Steenberg said that what they found is fascinating.

“We noticed the gains of sands had a very particular look—like they were shocked or fractured,” she shared. “And some of the data showed the rocks were actually inverted.”

The team is calling it the “Pine Bend impact.”

Scientists estimate that the meteor crash happened about 490 million years ago during the Cambrian period, which dates back about 250 million years before the dinosaurs roamed. At that time, life on Earth mostly consisted of “simple oceanic organisms.”

If the crater is confirmed, it will be the first for the state. And the Earth Impact Database will add it to its official list, which only includes 190 sites worldwide to date. About a third of those are buried like the Minnesota site.

A discovery such as this will help scientists better understand our past and future. But Steenberg pointed out that it doesn’t mean we need to worry about new meteors crashing into Earth’s surface. However, there are people keeping an eye on the sky just in case.

“It’s not something that we need to necessarily worry about in our lifetimes,” she added. “But to know it could happen and that NASA is even exploring ways to stop it happening is really interesting.”