Earth scientists have identified an impact crater in Australia that is more than a billion years older than any previously known, a discovery that could reshape our understanding of Earth’s early history and the conditions that led to life on our planet.
Researchers from Curtin University’s School of Earth and Planetary Sciences and the Geological Survey of Western Australia (GSWA) collaborated to study the 3.5-billion-year-old impact site in the North Pole Dome region of Western Australia’s Pilbara Craton. The findings challenge long-held assumptions about the planet’s early geological history, a period without clear evidence.
Pushing Back the Impact Crater Timeline
“Before our discovery, the oldest impact crater was 2.2 billion years old, so this is by far the oldest known crater ever found on Earth,” co-author Professor Tim Johnson of Curtin University said.
When a meteorite strikes Earth, the extreme pressure from the impact creates distinctive rock formations known as shatter cones—the only unequivocal macroscopic evidence of a meteorite collision. The team identified these formations at the newly discovered impact site, where a meteorite traveling over 36,000 kilometers per hour left behind a crater estimated to be 100 kilometers wide. The impact would have had planetary-scale consequences, scattering debris across the globe.
While evidence of ancient impacts on the Moon is well-documented, researchers are now uncovering more traces of similar events on Earth.
“We know large impacts were common in the early solar system from looking at the Moon,” Professor Johnson said. “Until now, the absence of any truly ancient craters means they are largely ignored by geologists. 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.”
Ancient impact craters may have played a key role in creating habitable environments on early Earth. The shape of these basins could have provided ideal conditions for mixing essential chemical ingredients in warm, water-rich environments—potentially forming the primordial soup that gave rise to microbial life.
“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,” said co-author and Cutin Professor Chris Kirkland.
Impact Shaping
Beyond the implications for life’s origins, the discovery offers new insights into Earth’s crust formation. Scientists have long debated how much influence cosmic impacts had on shaping the planet’s crust between 4.5 and 2.2 billion years ago. Still, the lack of craters older than 2.2 billion years has limited geological studies. Over time, erosion and plate tectonics have erased much of the planet’s impact history.
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“It also radically refines our understanding of crust formation: the tremendous amount of energy from this impact could have played a role in shaping early Earth’s crust by pushing one part of the Earth’s crust under another or by forcing magma to rise from deep within the Earth’s mantle toward the surface,” Kirkland said.
The impact may also have contributed to the formation of cratons—the large, stable landmasses that serve as the foundation of continents.
Johnson, Kirkland, and the team’s paper, “A Paleoarchaean Impact Crater in the Pilbara Craton, Western Australia” appeared in Nature Communications on March 6, 2025*.*
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.