The plates start moving
Earth begins recycling its own surface
See it on the timeline →In depth
When plate tectonics began is contested; estimates range from 4 to 1 billion years ago. Evidence from the Barberton belt in South Africa and from the Pilbara points to something subduction-like operating around 3.2 billion years ago. Its significance is climatic as much as geological: the carbon cycle, in which CO₂ is locked into rock by weathering and returned through volcanoes, acts as a thermostat over millions of years. Without plate tectonics the carbon would stay locked in the crust, as it probably is on Venus and Mars. Plate tectonics is also what builds continents — and therefore all dry land.
For children
Earth's crust broke into large plates that began pushing against each other. Where they collide, mountains grow; where they pull apart, new rock rises. No other planet we know does this — and it is one reason Earth has kept a stable climate for so long.
Connects to
Part of Terra Saga — the story of Earth on a timeline. terrasaga.org