Early Plates

Scientists found the oldest direct evidence for Earth’s tectonic motion

- Marissa Grunes

THE COLOSSAL MOVEMENTS of tectonic plates shape our world, influencing the composition of Earth’s atmosphere, the planet’s protective magnetic field and perhaps even the flourishing of life. Now researchers have compelling evidence that some form of plate tectonics might have started as early as 3.48 billion years ago, according to a study in Science.

Using magnetic traces from ancient pieces of Earth’s crust, researchers found that a chunk of what is now Western Australia drifted toward the magnetic north pole over a few million years as part of South Africa remained stationary. It’s the earliest documented instance of relative plate motion by more than half a billion years, and it has implications for understanding early life on Earth and how the planet’s tectonic activity began. [Disclosure: The author of this article embedded with the research team during last year’s field season.]

Earth today is a jigsaw of giant chunks of crust that travel across the planet, smashing together like huge bumper cars, pushing up mountain ranges and melting back into magma along their edges. All this activity, called plate tectonics, seems to be unique in our solar system. It’s believed that our rocky neighbor planets instead have a continuous, solid shell.