How could water have reached the deep Earth so early?

The researchers propose a mechanism they call "dripduction." In their model, dense, water-soaked portions of Earth's cooler outer crust periodically sagged downward and broke off into the hotter mantle below, carrying their water load with them.

That descending water lowered the melting temperature of surrounding mantle rock, producing magma. The magma rose, erupted at volcanoes, and cooled into the rocks the team now studies. Those rocks therefore record a moment when surface water reshaped Earth's deep interior.

"What surprised us was finding evidence that large amounts of water had already made their way deep into the Earth's interior and influenced the formation of volcanic rocks," Vandenburg said.

Why does the timing matter?

Geologists have long argued over when Earth first began recycling material between its surface and its deep interior. The process drives volcanism, builds continents, and transports elements on which life depends.

The Pilbara evidence pushes that recycling clock further back than previous evidence allowed. It points to a young Earth that was more dynamic than older models suggested.

"The Earth wasn't operating exactly as it does now, but it appears some of the key processes were already in place," Vandenburg said.

What makes the Pilbara Craton so valuable?

Rocks older than three billion years are rare. Most early crust has been melted, buried, or eroded many times over. The Pilbara Craton is one of the few places where such ancient stone survives in good condition, giving scientists a rare window onto early Earth conditions.

By measuring ratios of rare earth elements and isotopes of hafnium and neodymium, the team could reconstruct where the lavas came from. The signatures matched a hydrated mantle source rather than a dry one.

Which institutions contributed?

The collaborative study brought together researchers from:

• Adelaide University
• Monash University
• Geological Survey of Western Australia
• Curtin University
• Australian National University
• Cardiff University
• GEOMAR Helmholtz Center for Ocean Research (Germany)

What are the study's limits?

The evidence comes from a single craton and a small set of rock samples. Whether dripduction operated across much of the early Earth — or remained a local effect — remains open. More geochemical work will be needed to pin down how much water the process carried and how often it occurred.

Still, the result adds a clear data point to a long-running debate. It suggests the engine of plate tectonics had an older, simpler predecessor — one already ferrying the planet's most essential liquid underground.