Wednesday, June 18, 2008

Sea Level Factor in Mass Extinction

source: http://www.thetechherald.com/article.php/200825/1243/Sea-level-factor-in-mass-extinctions

Scientists have linked the rise and fall of the sea as the primary cause of mass extinctions over the past 500 million years. Image: Ko Phi Phi Beach, Thailand. Credit: DeepBluC/flickr

Scientists have linked the rise and fall of the sea as the primary cause of mass extinctions over the past 500 million years. Image: Ko Phi Phi Beach, Thailand. Credit: DeepBluC/flickr


The rise and fall of the Earth's seas are the primary cause of mass extinctions over the past 500 million years according to a new study.

Rather than asteroids or volcanoes, a team from the University of Wisconsin has found sea level the paramount factor in the sudden demise of creatures on the Earth.

"The expansions and contractions of those environments have pretty profound effects on life on Earth," says Shanan Peters, a University of Wisconsin-Madison assistant professor of geology and geophysics and the author of the new study published in the journal Nature.

"Paleontologists have been chipping away at the causes of mass extinctions for almost 60 years," says Peters. "Impacts, for the most part, aren't associated with most extinctions. There have also been studies of volcanism, and some eruptions correspond to extinction, but many do not."

The new study shows a significant relationship between the sea and previously unexplained mass extinction events. The research does not rule out impacts from meteorites or volcano activity in the case of the dinosaurs but does show the link between sea levels rises, in response to climate change or tectonic plate shifts, and most of the mass extinctions.

Peters examined two different types of rock records, one where sediments are derived from erosion of land and the other composed primarily of calcium carbonate, which is produced by shelled organisms.

"The physical differences between (these two types) of marine environments have important biological consequences," Peters explains.

The study received backing from the National Science Foundation.

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