ST. LOUIS, June 16 (UPI) -- A geologist at St. Louis University spotted rocks in China that are the oldest ever found but others had dismissed as black volcanic rock.
Timothy J. Kusky told the St. Louis Post-Dispatch the rocks resembled pillow lavam, deposits that form when molten, liquid rock from Earth's interior oozes out of cracks in the ocean floor.
These particular rocks are 2.5 billion years old, making them the oldest bits of sea floor ever discovered, not to mention the most ancient evidence to date for one of geology's pet theories: plate tectonics.
In the sea, the crust is both born and consumed. Ocean ridges, also known as spreading zones, are the sites where new crust is built and the heat of the world is cooled.
Scientists have hypothesized primitive bacteria living in ocean vents could have produced oxygen that allowed conditions on Earth to favor additional forms of life.
The hypothesis could never be tested before Kusky discovered the rocks.
