BRR: Around the world, miles of rock are missing. Could ‘Snowball Earth’ be the culprit?

“There must have been some sort of special event in Earth’s history that led to widespread erosion,” said Steve Marshak, a geologist at the University of Illinois at Urbana-Champaign who studies what has come to be known as the Great Unconformity.

New research suggests it was something special indeed. Scientists propose that several freak episodes of global glaciation scoured away miles of continental crust, obliterating a billion years of geologic history in the process.

The idea was first proposed back in 1973 by a geologist named William White, but no one took him seriously, said C. Brenhin Keller of the Berkeley Geochronology Center, who led the study published Monday in the Proceedings of the National Academy of Sciences.

“It’s an extraordinary claim that requires extraordinary evidence,” Keller said.

Today, however, researchers have come to accept the outlandish notion that, a few times in its 4.6-billion-year history, the planet froze over and became a “Snowball Earth.” Now Keller and his colleagues hope to convince their peers that the glaciers that crawled across the continents between 720 million and 580 million years ago were responsible for the Great Unconformity.

I certainly hope that doesn’t happen again.