Huge Impact Crater in Australia Breaks Record for World’s Oldest by Over a Billion Years

Scientists in Australia say they’ve found the world’s oldest impact crater, surpassing the previous record-holder’s age by more than 1.25 billion years.

The meteorite impact—in Western Australia’s Pilbara region—dates back 3.5 billion years, while the former record-holding impact crater is just 2.2 billion years old. By far, the Pilbara crater is the oldest known on Earth, the researchers say, and they managed to find it thanks to a distinctive rock formation. The team’s findings are published today in Nature Communications.

“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,” said Tim Johnson, a geologist at Curtin University in Australia and co-lead author of the study, in a university release.

The distinctive rocks that helped researchers identify the crater are called shatter cones, and they only form in the extreme environment caused by a meteorite impact. The space rock hit an area now known as the North Pole Dome, in a part of the Pilbara about 25 miles (40 kilometers) west of Marble Bar in Western Australia. The now second-oldest-known crater is also in Western Australia, at Yarrabubba.

According to the release, the meteorite that formed the more-than-62-mile-wide (100 km) crater hit the early Earth at more than 22,370 miles per hour (36,000 kilometers per hour).

The cones provide “unequivocal evidence” of a very high speed meteorite impact 3.47 billion years ago, the team wrote, and that the age of the impact is “statistically indistinguishable” from old rock beds in South Africa, indicating that the impact event may have kicked up rock that spread globally.

“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 Chris Kirkland, also a geologist and co-lead author of the study, in the same release.

Indeed, some of the world’s oldest evidence for life is found in the area of the meteorite impact. Stromatolites—microbial mat concretions found in warm, shallow waters off the coast of Australia—clock in at nearly 3.5 billion years old. Stromatolites offer an indication of what fossilized signs of life on Mars could look like. Last year, a group of researchers announced the discovery of the oldest known fossilized photosynthetic structures, which date back 1.75 billion years, and were also found in Australia.

“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 added. Previous evidence from the Pilbara—whose rocks are some of the oldest crusts on Earth—indicated that plate tectonics may have already been active on Earth between 3 to 4 billion years ago, when this staggering meteorite impact happened.