Australian Team Finds What Could Be World's Largest Asteroid Impact Spots

— -- Two deeps scars discovered in the Australian Outback are believed to be the site of one of the largest asteroid impacts ever.

The twin marks are believed to be indicators of what was once a 250-mile impact zone marking the moment the asteroid split into two pieces before impact, according to a study published in the journal Tectonophysics.

"It's a mystery -- we can't find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years," Andrew Glikson, lead researcher and a professor at Australian National University, said in a statement.

For example, evidence suggests a massive asteroid collision 65 million years ago led to the mass extinction of dinosaurs.

While the craters in the Australian outback have been covered over the course of time, the discovery came during a geothermal research project as a team drilled deep into the Earth's crust.

What they found were remnants of rocks that had been turned into glass, hinting at the possibility of an extreme event that changed the composition of the rocks.

Researchers looked even closer and found more evidence from Earth's crust.

"There are two huge deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below," Glikson said.

Researchers said the date of the impacts is unclear, however they have evidence from surrounding rocks that that puts it at 300 million to 600 million years old.

Most confusing of all is that there is no evidence surrounding the rocks of a mass extinction, leading scientists to have more questions than answers.