Tectonic movements of Earth's crust began at least 3.8 billion years ago, according to new evidence from the oldest known rock formation.
After Earth formed about 4.5 billion years ago, its cooling surface eventually developed continental plates and ocean basins that move as they do today. But scientists haven't known just when this transition to plate tectonics occurred.
Note: To comment, Science News subscribing members must now establish a separate login relationship with Disqus. Click the Disqus icon below, enter your e-mail and click “forgot password” to reset your password. You may also log into Disqus using Facebook, Twitter or Google.