Earth’s continental plates were moving 3.48 billion years ago

The arid hills of Western Australia’s Pilbara region contain the earliest evidence yet of tectonic plates sliding across Earth’s surface.

Tiny magnetic crystals locked in the bedrock recorded the terrain’s movement over time. Starting around 3.48 billion years ago, these rocks raced 2,500 kilometers poleward during a spurt lasting several million years, researchers report March 19 in Science. That pushes back the earliest physical evidence of plates moving by 140 million years.

“This is the only planet we know of that has [well-established] tectonics” and it’s important to understand when that began, says Alec Brenner, a paleomagnetic geologist at Yale University.