 
Geology prof's find shakes up debate |
Dr. Tim Kusky, a professor of geology, will unveil his findings Nov. 15 at the annual Geological Society of America meeting in Reno, Nev.
It has been widely held that plate tectonics, or the motion of plates and continents, dates back 1.5 billion years. Kusky is part of a group of geologists who believe the plates began moving billions of years before.
Kusky now believes he has the findings to prove it. This summer, Kusky discovered the oldest complete section of oceanic sea floor on the planet, which is more than a billion years older than previously known findings. During fieldwork in a mountain belt in the Eastern Hebei Province, Kusky and his colleague, Dr. Jiang-Hai Li of Peking University in Beijing, found the 2.7-billion-year old piece of oceanic crust.
The rocks date back to Earth's earliest geologic time period known as the Archean. The rocks are remarkably similar to much younger volcanic rocks that erupted on the sea floor in the process of sea floor spreading.
For decades, geologists have debated whether plate tectonics operated in the Archean period. Those who have argued against that theory have cited the lack of any Archean ophiolites as their main line of evidence that plate tectonics did not occur on the early Earth. Ophiolites are rock structures formed on the sea floor when continents collide.
"This discovery shows that the plate tectonic forces that create oceanic crust on the Earth today were in operation more than 2.7 billion years ago," Kusky said.
Kusky said the findings could have a more far-reaching effect on theories related to the development of life on the planet. During the Archean period, scientists believe life on Earth consisted mainly of single-celled organisms in the oceans. Just when they evolved into more complex organisms has been contested for years.
"This discovery also has implications for how life may have originated and diversified on Earth, as hot volcanic vents on the sea floor may have provided the nutrients and temperatures needed for life to flourish and develop," Kusky said. It is possible that life developed and diversified around volcanic vents on the sea floor related to sea-floor spreading."
Geochemical analyses and additional dating of the rock samples are under way at Saint Louis University, Washington University and Peking University. Approximately 30 of the leading scientists on both sides of the debate plan to travel to the Chinese province in December 2001 to view the discovery.
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