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OSU Scientists Finds Evidence for Largest Crater

Scientists generally agree that a giant meteorite slammed into the Earth 65 million years ago, killing off the dinosaurs. The impact left behind what has been believed to be the world's largest crater off the coast of the Yucatan Peninsula in Mexico. But recently, OSU scientists found evidence for an even larger crater and a larger meteor impact in Antarctica.

In one of the most remote regions of the Earth, under a thick layer of ice, lies what may be the largest impact crater on the planet. Last month, scientists at OSU announced they found evidence of a 250 million year old crater. The crater is more than 300 miles wide, making it bigger than the entire state of Ohio. The meteorite that caused such a large crater would've had to be almost 30 miles wide - about as big as the city of Columbus.

Scientists theorize this catastrophic impact might've caused the deadliest mass extinction in history - The Permian-Triassic Extinction, or The Great Dying. The impact also might've had a hand in breaking apart the Gondwana supercontinent, causing what is now Australia to split off from Antarctica.

Despite its size, no one noticed this crater-like object because of its hard-to-reach location. OSU geology professor Ralph von Frese is the lead scientist of the research team.

"You're talking about an object that's buried beneath over a mile and a quarter of ice so it's an object that actually in the history of humanity may never have been observed by a human," he said.

Von Frese and his colleagues used new satellite data to find the crater. The satellite mapped tiny variations in the gravitational field over Antarctica. These slight differences in the gravitational field trace out differences in the density of the Earth's surface.

The scientists found the region known as the Wilkes Land was denser than its surroundings. This suggests that it might've been the target of a meteorite.

"It's a model that's consistent with observations that we've made on the moon and mars and other places where you see a lot of impacts and craters," von Frese said.

A meteor impact causes a recoil effect that pulls up material from just beneath the surface. This makes that part of the surface denser, almost like a callous under your foot.

When scientists looked at satellite radar images, they found a circular ridge surrounding the denser region. This immediately led von Frese to believe they were staring at a giant meteor crater.

"It wasn't hard to put two and two together once you knew what you were looking for," he said.

Still, like any good scientist, von Frese remains cautious and skeptical.

"The problem is of course finding evidence for this impact. If it had a global effect, you would think you would find pieces of meteorite and rocks and so forth in places like Australia and surrounding areas that were connected before 100 million years ago," he said.

Von Frese wants to go on an expedition to the coast of Antarctica to dig for rocks, and to confirm that this is indeed a crater.

He also hopes the chances of securing funding for such a costly expedition will improve because of all the recent media attention he has gotten. Von Frese and his team hadn't expected such fanfare when they first presented their ideas last month at a geophysicists' meeting in Baltimore.

"It didn't catch the attention of much scientists, but apparently did catch the attention of reporters," von Frese said.

Graduate student and research team member Stuart Wells is enjoying the attention. "It's been real exciting to have people say, 'hey I've seen your story on,'" he said.

Von Frese is preparing to present his research at a conference next month in Tasmania. While he is excited about the promise of his work, he welcomes debate and peer review from the scientific community.