According to a recent geological study, the Stac Fada Member, northwestern Scotland’s most prominent geological formation, may be thick enough to pound a nail with. It was formed by a huge meteorite strike, about 990 million years ago. Curtin’s Professor Chris Kirkland from Curtin’s Frontier Institute for Geoscience Solutions made a world-first groundbreaking announcement. This finding upends the long-held belief that the impact happened 1.2 billion years ago. The resulting findings, now published in the journal Geology, completely overhaul Scotland’s geological history. They further reshape our view of when, where, and how non-marine life appeared on Earth in its early history.
The Stac Fada Member has an truly unique layer of rock. Yet, this layer of our earth provides important windows into the paleolithic past of our planet. It acts as a geological time capsule, providing the most profound of clues about the environment that existed on Earth when the impact struck. The research team utilized tiny zircon crystals from the Stac Fada Member as geological “time capsules,” allowing them to accurately date the impact and its implications for early life forms.
New Findings on an Ancient Impact
The new research uncovers a thrilling relationship. This meteorite strike occurred during a pivotal moment in Earth’s history, when the first freshwater eukaryotes began to evolve, acting as the ancient precursors to modern plants, animals, and fungi. This surprising correlation between diversity and mortality raises fascinating questions about the impact of large-scale impacts on these early ecosystems.
Professor Kirkland explained the significance of their findings, stating, “The revised dating suggests these life forms in Scotland appeared at a similar time to a meteorite impact.” The evolution of complex life thanks to environmental shifts caused by multiple impacts. This interdisciplinary connection would lead to incredible new opportunities for understanding evolution on that dramatic time period.
Challenges arose for the research team as they attempted to date this impact. This was due to the nature of zircon crystals specifically. Professor Kirkland elaborated on their methodology: “When a meteorite hits, it partially resets the atomic clocks inside the zircon crystals and these ‘broken timepieces’ are often unable to be dated. We developed a model to reconstruct when the disturbance occurred, confirming the impact at 990 million years ago.”
Implications for Earth’s Evolutionary Narrative
The confirmation that a meteorite strike caused the Stac Fada Member adds to the growing body of evidence indicating that extraterrestrial events significantly influenced Earth’s evolutionary trajectory. Together, these impacts led to the degradation of environmental quality and conditions. It’s unclear, but this change may have drastically shaped the way that early ecosystems formed.
“This raises fascinating questions about whether large impacts may have influenced environmental conditions in ways that affected early ecosystems,” Professor Kirkland noted. These types of considerations may open up new lines of hypotheses about how life adapted and evolved after drastic shifts in conditions precipitated by these events.
Second, it gives readers an appreciation, a sense of wonder, for what is happening in those zircon crystals, which are recording the moment of impact with extraordinary precision. According to Professor Kirkland, “These microscopic crystals recorded the exact moment of impact, with some even transforming into an incredibly rare mineral called reidite, which only forms under extreme pressures.” This change adds more confirmation of the impact’s importance and possibly its significance to shaping the Earth’s geologic landscape.