Reassessment of Miralga Crater Challenges Claims of Earth's Oldest Impact Site

In a significant development for planetary science, a recent study has challenged the prevailing belief regarding the age and significance of the Miralga impact structure in Western Australia, which was previously thought to be the oldest impact crater on Earth. The initial study, published by a different group, claimed that the crater formed approximately 3.5 billion years ago. However, the new findings, published on July 16, 2025, in the journal Science Advances by researchers including Aaron J. Cavosie, a senior lecturer at Curtin University, suggest that the crater is, in fact, much younger—dating back to at least 2.7 billion years ago, and potentially even more recent.

The Miralga crater, located in the arid Pilbara region, was initially proposed to have a diameter exceeding 100 kilometers and was thought to have played a crucial role in shaping continental crust and possibly influencing early life on Earth. In contrast, Cavosie and his colleagues have determined that the crater's diameter is only about 16 kilometers, underscoring its limited geological impact.

This discrepancy highlights the complexities of dating geological formations and the challenges researchers face in interpreting ancient events. According to Dr. Cavosie, "Geologists often rely on various dating methods and geological principles to establish timelines, but differences in interpretations can lead to vastly different conclusions."

The research team utilized the law of superposition, which posits that in undisturbed sedimentary rock layers, older layers lie beneath younger ones, to assess the crater's age. They identified shatter cones—distinctive formations resulting from high-pressure meteorite impacts—within both ancient and younger rocks. This evidence indicates that the impact event occurred after the formation of these younger layers, thereby establishing a new timeline.

The original study's assertion relied on the presence of shatter cones found in rocks dated to 3.47 billion years ago. However, Cavosie’s team discovered additional shatter cones in younger rocks, suggesting a more recent impact event. The newly proposed timeline places the crater's formation between 2.7 billion and 400 million years ago, a substantial difference from the earlier estimate.

The naming of the crater as the "Miralga impact structure" honors the traditional heritage of the local Nyamal Aboriginal people, further emphasizing the importance of cultural recognition in scientific discourse.

This research has broader implications, both for our understanding of Earth’s geological history and for planetary science as a whole. The unique composition of the Miralga crater, formed in ancient basalt, provides a rare opportunity for scientists to study impact processes that may also occur on Mars, where similar geological formations exist. As Dr. Cavosie notes, “The Miralga impact structure serves as a valuable analog for studying the cratered surfaces of other celestial bodies, particularly Mars, which may have experienced similar impacts in its history.”

As the research community continues to explore the geological past, these findings serve as a reminder of the dynamic nature of scientific inquiry—where new evidence can reshape established narratives and lead to a deeper understanding of our planet and beyond. Further studies and ongoing isotopic dating efforts are expected to refine the timeline of the Miralga impact structure, potentially unveiling more insights into Earth’s formative years and its relationship with other planetary bodies.

In conclusion, while the Miralga crater may not hold the title of the oldest impact site on Earth, it remains a scientifically significant structure that enriches our understanding of geological processes and impacts in the early solar system. The ongoing investigation into this site exemplifies the continuous evolution of scientific knowledge and the collaborative efforts of researchers to unravel the mysteries of our planet's history.