|Posted by arleneteng on July 14, 2009 at 6:43 AM|
by Stuart Wolpert
A new picture of the early Earth is emerging, including the surprising finding that plate tectonics may have started more than 4 billion years ago -- much earlier than scientists had believed, according to new research by UCLA geochemists reported Nov. 27 in the journal Nature.
"We are proposing that there was plate-tectonic activity in the first 500 million years of Earth's history," said geochemistry professor Mark Harrison, director of UCLA's Institute of Geophysics and Planetary Physics and co-author of the Nature paper. "We are reporting the first evidence of this phenomenon."
"Unlike the longstanding myth of a hellish, dry, desolate early Earth with no continents, it looks like as soon as the Earth formed, it fell into the same dynamic regime that continues today," Harrison said. "Plate tectonics was inevitable, life was inevitable. In the early Earth, there appear to have been oceans; there could have been life ? completely contradictory to the cartoonish story we had been telling ourselves."