Discovery offers clues into tectonic plates' history

Australian scientists drilling into the Pacific Ocean seafloor have discovered that distinctive rocks formed after the Pacific tectonic plate changed direction and began to plunge under the Philippine Sea Plate about 50 million years ago.

The scientists, part of an international expedition, made the finding recently after drilling into the seafloor. They say the discovery will help them understand the huge earthquakes and volcanoes that form where the Earth's plates collide and one plate gets pushed under the other.

"It's a bit like a rugby scrum, with two rows of forwards pushing on each other. Then one side goes down and the other side goes over the top," study leader Professor Richard Arculus said on Monday.