Surprising Discovery: Earth’s ‘Oldest’ Impact Crater is Actually Much Younger, New Study Reveals

Have you ever misread a clock and gotten late? Sometimes, scientists face a similar challenge with Earth’s history. Geologists try to date events, but it can be tricky.

Recently, an ancient meteorite crater was discovered in the remote Pilbara region of Western Australia. Initially, researchers claimed it dated back 3.5 billion years, which would make it the oldest known impact site on Earth. If true, that would be a big deal!

Our own research looked at the same site and published findings in Science Advances today. We agree this area shows evidence of an ancient impact, but our conclusions differ sharply on its age and significance.

Planetary scientists are interested in ancient impacts because they help us understand how Earth formed. So far, the oldest recognized impact structure is the Yarrabubba crater, which is 2.23 billion years old, also located in Australia. The new impact site in the Pilbara is in an area known as North Pole Dome. Despite its name, it’s a hot and dry landscape.

The first study claimed the crater measured over 100 kilometers in diameter and influenced Earth’s early crust and even early life. However, our findings indicate that the crater formed much later—after 2.7 billion years ago—and was smaller, around 16 kilometers wide. In our view, this size would mean it likely had a minimal impact on the formation of continents or the development of life.

So how did two research teams reach such different conclusions? Both studies identified shatter cones at the site—these are unique geological features that form during an impact. However, while the other study found cones only in ancient layers, we discovered them in both ancient and younger rock layers.

This led us to conclude that the impact would have happened after the youngest rocks formed, placing it between 2.7 billion and 400 million years ago. We’re still working on more precise dating.

Interestingly, we mapped numerous shatter cones across a 6-kilometer area. Our data shows that the crater is substantially smaller than previously thought, which challenges earlier notions of its effects on Earth’s history. By the time of the impact, the region was already quite ancient.

While Miralga may not be the world’s oldest impact site, its unique basalt make-up is rare. These basalts are some of the oldest shocked rocks known. This could provide valuable insights not just about Earth but also about Mars, where similar conditions might have existed.

In short, the Miralga impact structure serves as a laboratory for scientists studying both craters on Earth and potential signs of life on Mars. It’s an exciting time for planetary science!

This research reminds us that science is always evolving. New findings can reshape what we think we know. For more information on ancient impacts and craters, you might want to check out [NASA’s overview of impact craters](https://www.nasa.gov/mission_pages/asteroids/news/asteroid-craters.html).

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