A meteorite that struck northwestern Scotland about a billion years ago may have collided 200 million years later than initially believed.
New research from Curtin University in Australia analyzed tiny crystals left behind by the impact and found that they were younger than previously thought. This new information could change what science knows about Scotland’s rich geological history and the general understanding of how non-marine life evolved on Earth.
Scotland’s Meteorite Strike
Along Scotland’s northwestern coast is a layer of rock known as the Stac Fada Member. The Stac Fada Member is part of the larger Stoer Group, which consists of sediment from the Mesoproterozoic Era that dates back to about 1.6 million years to 1 million years ago.
Within this layer are clues to understanding Earth’s ancient past, including a meteorite strike that may have influenced life on our planet. Strikes like these have shaped Earth in numerous ways, including the Chicxulub impactor that led to the fifth mass extinction event, or strikes that brought vital elements like minerals and water to Earth.
This particular strike, which hit Scotland nearly a billion years ago, appears to have hit much later than researchers initially thought. This change in timeline could help researchers fill in more gaps in the life’s evolutionary puzzle.
Read More: Carbon-Rich Meteorites Lose Their Shock Value After Exploding On Impact
Dating Ancient Crystals
For this study, researchers from Curtin University analyzed tiny zircon crystals, which they consider geological time capsules. From their analysis, they determined that the meteorite, originally thought to have struck Earth 1.2 billion years ago, had actually struck 990 million years ago.
“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,” Chris Kirkland, from Curtin’s Frontier Institute for Geoscience Solutions within the School of Earth and Planetary Sciences, said in a press release. “This provided undeniable proof that a meteorite strike caused the Stac Fada deposit.”
To determine the age of the crystals, the research team developed a new method of determining their atomic age.
“When a meteorite hits, it partially resets the atomic clocks inside the zircon crystals, and these ‘broken timepieces’ are often unable to be dated, but we developed a model to reconstruct when the disturbance occurred, confirming the impact at 990 million years ago,” Kirkland said in a press release.
Meteorites' Impact on Life
According to the study, this meteor impact occurred around the same time as the emergence of the first freshwater eukaryotes. Eukaryotes are organisms that have cells with a membrane-bound nucleus. Today, eukaryotes include most plant, animal, and fungi species.
“The revised dating suggests these life forms in Scotland appeared at a similar time to a meteorite impact,” Kirkland said in a press release. “This raises fascinating questions about whether large impacts may have influenced environmental conditions in ways that affected early ecosystems."
Although researchers know that a meteorite caused the Stac Fada Member, researchers continue to search for the impact site.
“While the impact crater itself has yet to be found, this study has collected further clues that could finally reveal its location,” Kirkland said. “Understanding when meteorite impacts occurred helps us explore their potential influence on Earth’s environment and the expansion of life beyond the oceans.”
Read More: Origins of Water on Earth May Not Have Started with an Asteroid Impact
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A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.
