Meteorite on the Gunflint Trail
, Associated Press
GRAND MARAIS, Minn. (AP) A meteorite that slammed into Earth 1.85 billion years ago at the present site of Sudbury, Ontario, is now making news 500 miles away in northeastern Minnesota.
The fire closed access to most areas the group had planned to visit, so Minnesota Geological Survey geologist Mark Jirsa went up the trail to scout new locations.
In a spot he had never visited, with fire in three directions, Jirsa found evidence of a cataclysm that probably no one but a geologist ! would have noticed debris from the
That blast created a crater more than 150 miles across, scattering rock and dust over nearly a million square miles.
"It’s fairly dark rock," Jirsa said. "They look like concrete, but in this concrete you would throw pieces of rock of all sizes and shapes and in all possible orientations."
The rock includes balls the size and shape of a large taconite pellet which Jirsa believes formed in the impact’s huge, hot cloud of dust, much as hailstones form in a storm cloud.
Jirsa says the Gunflint area probably was in or near a shallow sea when the meteorite stuck. He says there are indications that a huge tsunami may have ripped up the sea bottom and seashore, mixing them with rocks fallen from the sky into the concrete-appearing geological mess he found.
"The object was probably between 10 and 20 kilometers (6 and 12 miles) in diameter, and some of us think it was more likely to have been a comet than an asteroid, but there is no definitive evidence," Mungall said.
Previously, material thrown out by the meteorite’s impact had been found as far from
Jirsa said there’s still much work to be done in the field to determine what secrets the Gunflint site holds that other sites don’t.
"That’s the critical thing. This is a different geological setting; it’s a little! farther away from the impact, the rocks are altered differently. It may reveal some secrets about the impact that other discoveries haven’t yet. That’s what we’re hoping," Jirsa said.
"I think the excitement for the people of