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Apocalypse Then: Volcanic eruptions wiped out half of life on Earth 200 million years ago

By Catholic Online (NEWS CONSORTIUM)
March 22nd, 2013
Catholic Online (www.catholic.org)

It was Apocalypse - then. Scientists say that a series of massive volcanic eruptions wiped out half of life on Earth 200 million years ago. Researchers have linked the abrupt disappearance of half of the world's species to a precisely dated set of gigantic volcanic eruptions. More ominously, the eruptions may have caused climate changes so sudden that many creatures were unable to adapt . possibly on a pace similar to that of human-influenced climate warming today.

LOS ANGELES, CA (Catholic online) - It was all part of the cycle of life: Scientists say that the extinction opened the way for dinosaurs to evolve and dominate the planet for the next 135 million years. They ruled the world until they too, were wiped out in a later planetary cataclysm.

Many scientists have suggested that the so-called End-Triassic Extinction and at least four other known past die-offs were caused at least in part by mega-volcanism and resulting climate change. They were still unable to tie deposits left by eruptions to biological crashes closely in time.

The new study provides the most cogent link yet, with a newly precise date of 201,564,000 years ago, 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," Co-author Paul Olsen, a geologist at Columbia University's Lamont-Doherty Earth Observatory said. "However, the coincidence in time with the volcanism is pretty much ironclad," Olsen adds.

Lead author Terrence Blackburn used the decay of uranium isotopes to pull exact dates from basalt, a rock left by eruptions.

Previous studies suggested a link between the eruptions and the extinction, but other researchers' dating of the basalts had a margin of error of one to three million years.

A massive basalt flow In Clifton, New Jersey from the time of the End Triassic is exposed in a former quarry, now located behind a retirement home. Reddish sedimentary rocks signaling the extinction itself lie to the far right.

The new margin of error is only a few thousand years, which is a mere blink of the eye, in geological terms.

Blackburn and his colleagues showed that the eruption in Morocco was the earliest, with ones in Nova Scotia and New Jersey coming about 3,000 and 13,000 years later, respectively.

Fossils now show that heat-sensitive plants especially suffered. There is also evidence that the increased CO2 caused chemical reactions that made the oceans more acidic, causing populations of shell-building creatures to collapse.

There is also some evidence that a large meteorite hit the earth at the time of the extinction, but that factor seems far less certain.

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