Extinctions tied to Earth's volcanic past

NEW YORK, March 21 (UPI) -- U.S. scientists say the abrupt disappearance of half of Earth's species 200 million years ago has been linked to a dated set of gigantic volcanic eruptions.

Researchers from Columbia University say the eruptions may have caused climate changes so sudden that many species were unable to adapt, and the pace of those changes could have occurred at a rate similar to that of human-influenced climate warming.

Geological deposits date the so-called End-Triassic Extinction at precisely 201,564,000 years ago, they said, exactly the same time as a massive outpouring of lava.

"This may not quench all the questions about the exact mechanism of the extinction itself," Columbia geologist Paul Olsen said. "However, the coincidence in time with the volcanism is pretty much ironclad."

The geologic deposits analyzed in the study were from the Central Atlantic Magmatic Province, a series of huge eruptions known to have started around 200 million years ago when nearly all Earth's land was massed into one huge continent.

The eruptions spewed an estimated 2.5 million cubic miles of lava in four sudden spurts over a 600,000-year span -- a period when pollen, spores and other fossils characteristic of the Triassic era disappeared, researchers said.

Deposits linked to the volcanic episodes have been found everywhere in the world the researchers have looked, leading Columbia paleomagnetism expert Dennis Kent to say the eruptions "had to be a hell of an event."