A Curtin University group has identified what may be Earth’s oldest meteorite strike in a remote part of Western Australia’s Pilbara region, near the North Pole Dome. Evidence in local rock indicates the collision happened around 3.47 billion years ago, easily exceeding the age of any other documented crater. Older research pointed to a 2.2-billion-year example, but this Pilbara site moves that benchmark by over a billion years. It highlights a phase in Earth’s past when extraterrestrial objects were far more frequent.
“(T)his is by far the oldest known crater ever found on Earth,” said Curtin Frontier Institute for Geoscience Solutions’s Tim Johnson and study co-lead.
There’s no gaping crater. Billions of years of geology at work through erosion and sedimentation has made this ancient impact invisible — but there are subtle signs it happened. The primary indicator is a geological feature called a shatter cone. These cone-shaped fractures form under extreme shock, radiating from the impact point. Researchers note that these specimens in Pilbara rocks are in excellent condition, helping them gauge the incoming object’s size. Early estimates suggest a crater possibly exceeding 100 kilometers across, creating a massive event that shaped the local environment.
Johnson said that meteorite strikes were more common in Earth’s youth. The Moon and its many pockmarks show that cosmic objects battered our planet heavily in its earliest times, yet direct proof is hard to find. The Pilbara site offers a new glimpse at how these collisions molded the surface. Large impacts unleash enormous energy, heating layers, fracturing crust, and hurling debris far and wide. Across long spans, erosion and volcanic action erase signs of such events.
Chris Kirkland, a study co-lead also examining the site, believes this event may have helped shape the planet’s earliest crust.
“Uncovering this impact and finding more from the same time period could explain a lot about how life may have got started, as impact craters created environments friendly to microbial life such as hot water pools,” Kirkland said, also from Curtin’s School of Earth and Planetary Sciences. “It also radically refines our understanding of crust formation.”
The researchers believe the extreme heat and chemical activity generated by such impacts may have provided an early “home” for primitive life. The discovery of shatter cones shows that a powerful collision hit this watery environment, possibly creating hot springs and chemical-rich zones—much like modern underwater vents—where microbes could have taken hold. Tiny spherical droplets in nearby rock also hint at additional strikes, making this site a rare glimpse into the period when Earth’s surface first formed.
The crater sits within a rock layer called the Antarctic Creek Member, which includes shattered material filled with carbonate minerals and overlying volcanic layers containing “pillow” shapes from ancient lava meeting water. Researchers found no trace of shatter cones in the upper layers, indicating the cones formed much earlier. They note that while massive meteorite impacts happened often in Earth’s early days, most of their remains have been erased.
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They conclude that Pilbara preserves clear, ancient evidence of a colossal impact, promoting fresh discussions on how cosmic bombardments may have shaped Earth’s surface and possibly spurred the growth of the planet’s earliest life forms.
While more study is needed, the team believes that advanced mapping and deeper examination of greenstone belts might uncover many other collision sites from early geological history. These belts, often located in the cores of ancient cratons, hold clues in their volcanic and sedimentary layers. Investigators hope that as knowledge grows, more direct proof of ancient bombardment will appear, highlighting the chain of events that shaped the world in its initial chapters and perhaps played a role in life’s beginnings.
“Until now, the absence of any truly ancient craters means they are largely ignored by geologists,” Johnson said. “This study provides a crucial piece of the puzzle of Earth’s impact history and suggests there may be many other ancient craters that could be discovered over time.”
The study was published in Nature Communications.
