Freshwater first appeared on Earth 4 billion years ago, ancient crystals hint
Zircon chemistry may push back the water cycle’s start by hundreds of millions of years

An analysis of ancient zircon crystals from the Jack Hills formation (shown in a satellite image) in Western Australia suggests freshwater was cycling on Earth hundreds of millions of years earlier than previously thought.
NASA/GSFC/METI/ERSDAC/JAROS, U.S./Japan ASTER Science Team