Earth's earliest history is shrouded in mystery, because the shuffling of tectonic plates has erased many geological clues. One of the few lines of evidence comes from zircon crystals, which preserve chemical information in their durable mineral structures. A zircon study published today finds that the ancient Earth could have contained more oxygen ' and possibly more water ' than researchers had suspected, and suggests that the movement of tectonic plates was already happening at least 3.3 billion years ago, relatively early in Earth's 4.5-billion-year-old history1. The presence of more oxygen than expected in these ancient rocks suggests that conditions on the planet could have been more conducive to life during this period than previously thought. And if tectonic plates were already moving, this suggests that Earth was already hosting some of the geological processes that shape the planet and that ' by recycling crucial chemicals ' help to make life possible. The work is just one...
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