A rare meteor crash site was first discovered in Inver Grove Heights, Minnesota, and researchers hope it will soon be added to a map of other known crash sites around the world.
“I’ve been looking at rock samples all day and I’ve never seen anything like it before,” said Julia Steenberg, a geologist and research scientist at the University of Minnesota. “It’s like taking a breath of fresh air to find and explore something new.”
There are approximately 190 approved sites worldwide, of which 30 are in the United States.
“We’re geology buffs, and that really gets us excited,” said Tony Runkel. The chief geologist at the Minnesota Geological Survey said the site was “definitely” one of the most intriguing findings in his 33 years of surveying.
The crater below Inver Grove Heights is about 2.5 miles wide and can extend up to 9 square miles in total. Growing up in Dakota County, Steenberg said it dates back about 490 million years.
The crater itself is hidden several hundred meters deep under the sediment and is not visible to the human eye, he said.
Scientists from the Minnesota Geological Survey, the research arm of the U’s School of Earth and Environmental Sciences, found the meteorite impact site while updating geological maps of Dakota County in early 2021. Steenberg said they named it the Pine Bend Impact after the Inver Grove Heights area it is located in.
Under most of the state’s land are flat layers of glacial sediment. Beneath the glacial layers are sandstone, limestone and shale. While the scientists were working at Inver Grove Heights, they found that the layers that were often stacked in a predictable order were distorted and some layers appeared to have been knocked over.
“The more I looked at the records in that area, the more they didn’t make any sense,” Steenberg said. Said.
He remembered finding small, broken grains of sand known as shock quartz, a common descriptor of the meteor impact. Grains are simply created by the impact of a meteorite or by the dramatic shock and compression of a nuclear explosion, he said.
Most of the time meteorites burn up before they hit Earth – but sometimes a collision does occur, Steenberg said.
“There is such intense pressure … it produces instantaneous geological effects,” he said.
For verification, Steenberg sent photographs and samples of the sediment to the Museum of Natural History in Vienna, Austria, and the Institute of Geosciences of the University of Brazil. They confirmed it was actually shocked quartz.
Steenberg said the researchers had learned about the site and wanted to find the exact size of the meteor, adding that U hopes to raise funds for the study. He added that they plan to publish their findings and maps soon.
Since the site has just been discovered, it has not yet been included in the official sites. World Impact Database“Though researchers hope it will be added,” he said.
In the Upper Midwest, domains have been found in Wisconsin, North Dakota, and Iowa. Rock Elm Crater in western Wisconsin, approximately halfway between the Twin Cities and Eau Claire, is the closest known crater to Minnesota. It’s about 3.7 miles in diameter and Pine Bend Impact is a bit younger than thought, Steenberg said.
Inver Grove Heights spokesperson Amy Looze said residents are excited to see Pine Bend Impact as part of the city’s history.
“We are delighted, concerned and relieved by Ms. Steenberg’s discovery,” Looze said in an email. “I am pleased about that [we] He wondered if the discovery could become an important geological site, could give scientists more data they need to predict future meteor impacts on Earth, and he was relieved that there was zero statistical chance for another meteor to hit our city.”
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