These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass. As the overlying plate lifts up, it also forms mountain ranges. In addition ...

This early rocky shell featured chemical signatures previously thought to occur only in continental crusts made by the process of subduction, in which one tectonic plate slides under another. But ...

Plate tectonics then fell into a continuous, self-sustaining pattern. "This discovery completely changes our understanding of Earth's earliest geological processes," says Professor Turner.