Around 3.5 billion years ago, an enormous meteorite travelling more than 36,000km/h crashed into what is now the North Pole Dome in Western Australia’s Pilbara region.
The impact would have been phenomenal, creating a crater over 100km (62 miles) wide and sending debris spinning around the globe.
Scientists knew nothing of this ancient hole in the ground, until a series of 'shatter cones' were recently discovered on a hillside near the town of Marble Bar.
These distinctive "hut-like" rock formations, some several metres tall, only form under the intense pressure of a meteorite strike, so Professor Tim Johnson and his colleagues from Curtin University knew they had found something special.
The discovery provides "unequivocal evidence for a hypervelocity meteorite impact 3.47 billion years ago" and could explain a lot about how life may have started, say the researchers, who published their findings in the journal Nature Communications.
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Oldest-ever meteorite impact crater
"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," says Johnson.
"We know large impacts were common in the early solar system from looking at the Moon," Johnson explains, however, "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."
Why the discovery matters
The team says the discovery sheds new light on how meteorites shaped Earth's early environment.
"Uncovering this impact and finding more from the same time period could explain a lot about how life may have got started," says co-lead author Professor Chris Kirkland, also from Curtin University, who explains that "impact craters created environments friendly to microbial life such as hot water pools."
"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.
"It may have even contributed to the formation of cratons, which are large, stable landmasses that became the foundation of continents."
Find out more about the study: A Paleoarchaean impact crater in the Pilbara Craton, Western Australia
Main image: Pilbara Craton in Western Australia/Getty
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