The main clues to the origins of our planet (and life itself) are locked within three billion year-old volcanic rocks in Western Australia. These ancient rocks show that water was probably already shaping the Earth’s interior and driving volcanic activity more than three billion years ago.

The findings published today in the journal. Nature Communications They suggest that Earth was already running a version of the water recycling processes that shape our planet today, even though our home planet was a dramatically different place billions of years ago. Geologists found signs that about three billion years ago water traveled deep beneath the Earth’s surface, helping to create the magmas that formed volcanoes like those found today in the explosive Pacific Ring of Fire.

Every day, Earth’s water is continually recycled through a process called plate tectonics. Ocean water is transported to the middle layer or mantle of the Earth. Water is then dragged down into subduction zones. In these areas, one tectonic plate slides beneath another, fueling volcanoes that are powerful enough to form continents. However, billions of years ago, that internal water recycling process worked completely differently, if at all.

“The early Earth was too hot for the plates to behave that way.” [pulling water down to the mantle]” Dr. Eric Vandenburg, a co-author of the study and a geochemist at the University of Adelaide in Australia, said in a statement. “So until now it has been unclear whether surface water could have made that trip more than three billion years ago and, if so, how.”

In other words, it may have been too hot for Earth’s first plates to move water up into the mantle as they do today.

To find out more, the team studied rocks from Western Australia’s Pilbara Craton. The rocks formed between 3.6 and 2.8 billion years ago and are some of the oldest on Earth. Iron-rich rocks began forming before there was oxygen in Earth’s atmosphere, or even before there was life itself. The Pilbara remains one of the few places where geologists can study the young Earth.

The team analyzed chemical signatures preserved within the rocks of the Pilbara Craton and reconstructed events that occurred 3.1 billion years ago. Surprisingly, they found evidence that large amounts of water had already reached the depths of the Earth’s interior. All that water also influenced the formation of volcanic rocks. The team believes that while modern plate tectonics may not have existed on Earth yet, a different process may have brought water into the mantle.

So how could water reach so deep on Earth without plate tectonics? The team proposes that it was due to a mechanism they call dripping. During trickle-down, dense, water-rich sections of Earth’s cold outer crust sporadically sink and then collapse into the warmer mantle below. When these pieces of bark collapsed, they took water with them. The water was then released into the Earth’s mantle, creating magmas that fueled volcanic eruptions. When magma interacts with water, the intense heat turns that water into steam. The steam then expands and erupts along with the magma. That magma then solidified forming rocks that geologists still study today.

“The Earth wasn’t functioning exactly the way it does now, but it appears that some of the key processes were already underway,” Vandenburg said.

For geologists, understanding when water began moving deep underground helps explain one of our planet’s most critical processes. Plate tectonics influences everything from volcanic eruptions and continental growth. Moving plates can even produce some of the chemical elements necessary for life to exist. These findings provide clues about how Earth’s continents formed and how our planet evolved into what we know today.

According to the team, these new findings suggest that the Earth’s interior and surface may have been connected much earlier than we thought. Earth appears to have been a surprisingly dynamic young planet that was already recycling one of its most crucial ingredients: water.

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