A team of scientists from the Australian National University (ANU) has found the remains of a massive asteroid, about 20 to 30 kilometres wide, in a drill core from Marble Bar in northwestern Australia. The study published in the journal Precambrian Research reveals that the asteroid hit the young Earth with an impact harsher than anything humans have gone through.

“The impact would have triggered earthquakes orders of magnitude greater than terrestrial earthquakes,” says Andrew Glikson from the Australian National University’s Planetary Institute. “It would have caused huge tsunamis and would have made cliffs crumble.”

The researchers uncovered tiny glass beads called spherules, which were formed from the vaporised material from the impact. These spherules were found in sea floor sediments dating back 3.46 billion years ago.


Tiny impact spherules. Credit: ANU

The sediment layer was well-preserved between two volcanic layers, which allowed accurate dating. Further analysis reveals that the material contains levels elements that matched those found in asteroids such as chromium, platinum, and nickel.

The asteroid, which is among the largest ones and the second oldest one, could have also caused major tectonic shifts and massive magma flows that greatly affected the way Earth evolved. However, the researchers explain they do not know the exact location of the asteroid’s impact but the spherules could have spread across the globe when the asteroid hit Earth.

Moreover, the crater must have been hundreds of kilometres wide. Unfortunately, the crater is thought to be destroyed by tectonic plate movements and volcanic activities that occurred within billions of years.


Marble Bar sediments, a microcrystalline silicone-rich chert. Credit: ANU

Glikson has sought for proofs of ancient asteroid impacts for more than two decades now. The scientist says that there are probably more impacts similar to this one. “This is just the tip of the iceberg,” adds Glikson. “We’ve only found evidence for 17 impacts older than 2.5 billion years, but there could have been hundreds.”