The following essay is reprinted with permission from 
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We have discovered the oldest meteorite impact crateer on Earth, in the very heart of the pilbara region of western australia. The Crater formed more than 3.5 billion years ago, Making it the oldest knowledge by more than a billion yearsOur discovery is published today in Nature Communications,
Curiously enough, the carater was exactly where we had hoped it would be, and its discovery supports a theory about the birth of the first continents.
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The very first Rocks
The oldest Rocks on Earth formed More Than 3 Billion Years ago, and are found in the cores of Most Modern Continents. However, geologists still cannot agre how or wear they formed.
Nonetheless, there is agrement that these Early Continents Were Critical for Many Chemical and Biological Processes on Earth.
Many Geologists Think These ancient Rocks formed Above Hot Plumes That rose from Above Earth's Molten Metallic Core, Rather Like Wax in a Lava Lamp. Others maintain they formed by Plate Tectonic Processes Similar to Modern Earth, Where Rocks Collide and Push Each Other Over and Under.
Although these two Scenarios are very different, bot are driven by the loss of heat from within the interior of our planet.
We think raather differently.
A less years ago, we published a paper Suggesting that the energy required to make controlnts in the pilbara came from outside earth, in the form of one or more collisions with meteorites many kilometers in Diameter.
As the impacts blasted up enormous volumes of Material and Melted the Rocks Around Them, The Mantle Below Produced Thick “Blobs” of Volcanic Material That evolved into continental crust,
Our Evidence then Lay in the Chemical Composition of Tiny Crystals of the Mineral Zircon, About the size of Sand Grains. But to persuade other geologists, we needed more convincing evidence, preferably someating people could see without needing a microscope.
So, in May 2021, we began the long drive north from perth for two weeks of fieldwork in the pilbhaorGswa) To hunt for the carater. But where to start?
On the hunt for shatter contes in a typical pilbara landscape with our trusted gswa vehicles.
Chris Kirkland, Curtin University
A serendipitous bet
Our first target was an unusual layer of rocks knowledge as the antarctic creek member, which crops out on the flans of a dome some 20 kilometres in Diameter. The antarctic creek member is only 20 metres or so in thickness, and mostly comprises sedimentary Rocks that are sandwicheded by seveane several kilometres of dark, basaltic lava.
However, it also also contains spherules– Droplets formed from Molten Rock Thrown up during an impact. But these drops could have traveled across the globe from a giant impact anywhere on Earth, Most Likely from a CRATER That Has Now Been Destroyed.
After consulting the gswa maps and aerial photography, we located an area of the center of the pilbara along with a dusty track to begin our search. We parked the offroad vehicles and headed our separate way across the outcrops, more in hope than expectation, agreing to meet an hour later to discus what we'd found and grub a fit to eat.
Large Hut-LIKE SHATER CONES In the Rocks of the Antarctic Creek Member at the Discovery Site. The Rocks on the Hilltop farthest left are basalts that lay directly over the shatter cons.
Tim Johnson, Curtin University
Remarkably, when we returned to the vehicle, we all thought we'd found the same thing: SHATER CONS.
SHATTER CONES SRE BeOTIFUL, DELICATE BRANCHING Structures, Not Dissimilar to a badminton shuttlecock. They are the only feature of shock visible to the naked eye, and in natural can only form following a meteorite impact.
Little more than an hour into search, we had found preachisely what we we looking for. We had literally open the doors of our 4wds and stepped onto the floor of a huge, ancient impact crateer.
Frustratingly, after taking some photos and grabbing a few samples, we had to move on to other sites, but we determined to return as soon as possible. Most importantly, we needed to know how old the shatter cons was. Had we discovered the oldest knowledge crateer on Earth?
It turns out that we had.
An Approximately One Meter Tall Shatter Cone 'Hut', with the rolling hills of the pilbara in the background.
Chris Kirkland, Curtin University
There and back again
With some laboratory research under Belts, we returned to the site in may 2024 to spend ten days examing the evidence in more detail.
SHATTER CONES WORE EVERYWHERE, Developed through the antarctic creek member, which we traced for several hundred metres into the rolling Hills of the pilbara.
Our observations shows that life the layer with the shatter contes was a thick layer of basalt with no evidence of impact shock. This meant the impact had to be the same age as the antarctic member Rocks, which we know are 3.5 billion years old.
DELICATE SHATER CONS Within Rocks Typical of the Antarctic Creek Member.
Tim Johnson, Curtin University
We had our age, and the record for the oldest impact crateer on Earth. Perhaps our ideas registered the ultimate origin of the continents was not so Mad, as many told us.
Serendipity is a marvelous thing. As far as we knew, other than the traditional owners, the nyamal people, no geologist had laid eyes on these stunning features insceay.
Like some others before usWe had argued that meteorite impacts played a fundamental role in the geological history of our planet, as they clearer Other planets, moons and asteroidsNow we and others have the chance to test these ideas based on hard ever.
Who Knows how many ancient craters lay healthy in the ancient cores of other continues? Finding and studying them will transform our undersrstanding of the Role of Giant Impacts, Not Only In the Formation of the Formation of the Landmases on which we all live, but in the origins of life Itself.
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