Earth’s oldest crystals suggest an early start for plate tectonics

Chemical evidence from ancient crystals suggests that Earth’s tectonic plates had already started moving 3.3 billion years ago, relatively early in our planet’s history. By analysing zircon crystals recovered from Western Australia — the oldest-known fragments of Earth rocks — researchers also found that the ancient Earth could have contained more oxygen, and possibly more water, than suspected. The movement of tectonic plates and higher-than-expected oxygen levels suggest that conditions on Earth could have been more conducive to life during this period than previously thought.