Source: http://www.sciencedaily.com/releases/2008/11/081126133357.htm

ScienceDaily (2008-11-27) -- A new picture of the early Earth is emerging, including the surprising finding that plate tectonics on Earth may have started more than four billion years ago -- much earlier than scientists had previously believed.


"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."

"We're revealing a new picture of what the early Earth might have looked like," said lead author Michelle Hopkins, a UCLA graduate student in Earth and space sciences. "In high school, we are taught to see the Earth as a red, hellish, molten-lava Earth. Now we're seeing a new picture, more like today, with continents, water, blue sky, blue ocean, much earlier than we thought."

The Earth is 4.5 billion years old. Some scientists think plate tectonics — the geological phenomenon involving the movement of huge crustal plates that make up the Earth's surface over the planet's molten interior — started 3.5 billion years ago, others that it began even more recently than that.

University of California - Los Angeles (2008, November 27). Plate Tectonics Started Over 4 Billion Years Ago, Geochemists Report. ScienceDaily. Retrieved November 27, 2008, from http://www.sciencedaily.com/releases/2008/11/081126133357.htm#