Scientists to Search for Ancient Scottish Meteorite Crater
A huge meteorite is believed to have cascaded into what is now The Minch – separating mainland Scotland the Western Isles – around 1.2 billion years ago.
Scientists believe there could be an undiscovered meteorite crater beneath the sea in The Minch, located in the northwest of Scotland.
The theory has prompted researchers from the University of Oxford and the University of Aberdeen to call for a full geophysical survey of the strait to find the elusive crater. In 2008, scientists first raised the idea that a crater may exist between the Western Isles and the Scottish mainland.
Debris evidence found along the Highland coast suggests that a significant impact occurred around 1.2 billion years ago. Evidence to support the theory comes in the form of red-coloured rocks, known as the ‘Stac Fada Member’ – found on the eastern coast of The Minch.
During the impact, the ‘ejecta blanket’ would have propelled the rocks up to 50km away. Some of these are up to 15 metres thick and contain shocked quartz. This is a type of mineral that has sustained extreme levels of pressure and is often associated with seismic or meteorite events.
During this period, known as the Mesoproterozoic Era, the arrangement of the planet’s continents differed enormously to what we see today. Much of the Earth’s landmass would have contained no plant life, while most primitive life inhabited the oceans. At the time, Scotland would have also been located close to the equator.
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Speaking to the BBC, Dr Ken Amor of the University of Oxford said that a number of methods allow researchers to potentially trace back the source of the rocks found on the eastern half of The Minch and pinpoint a location underneath the sea.
“If you image debris flowing out in a big cloud across the landscape, hugging the ground, eventually that material slows down and comes to rest,” he said.
“But it’s the stuff out in front that stops first while the stuff behind is still pushing forward and it overlaps what’s in front. That’s what we see and it gives us a strong directional indicator that we can trace backwards,” Dr Amor added.
“Also, we’ve examined the orientation of magnetic particles within the fabric of the rock at several locations, and this too allows us to triangulate back to an origin.”
These paths, Dr Amor suggested, eventually converge; allowing researchers to pinpoint a general location within the strait.
Seismic surveys conducted during the 1970s are also being analysed by the researchers, Dr Amor said. These were conducted during an oil prospecting programme but the data is of poor quality. Gravity data is also being investigated as part of the project, which shows there is an anomaly located within the strait.
“What we really need is a new high-resolution geophysical survey – a 3D seismic survey,” Dr Amor explained. “Unfortunately, being offshore that would cost a lot of money. I shall be putting in a grant proposal to do some seismic work. That would be a first step and would greatly assist the definition of any impact structure.”