Plate tectonics reveals evidence of ancient sea beneath the Philippines

Washington Post : Researchers say an ancient sea may have existed some 52 million years ago at the intersection of three major tectonic plates: the Eurasian, Pacific, and Indo-Australian. Through the use of seismic tomography, Jonny Wu and John Suppe of National Taiwan University were able to peer some 500–1300 km below Earth’s crust into the mantle below the Philippine Sea and search for tectonic plates that had been subducted under other plates. The researchers found 28 such plates floating in the mantle and used software to virtually stitch them together like a jigsaw puzzle. The scientists conclude that the ancient plate sat at the bottom of a sea that at one time may have covered more than 15 million km². The sea shrank over time, however, as the three major tectonic plates shifted and caused pieces of the plate under the sea to subduct one by one into the mantle.