By Paul Rincon
Science reporter, BBC News
Evidence of the biggest meteorite ever to hit the British Isles has been found by a team of scientists.
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The space rock struck the ground near the present-day town of Ullapool, they report in Geology journal.
The scientists found what they believe to be debris which was flung out when the meteorite crater was formed.
"If there had been human observers in Scotland 1.2 billion years ago they would have seen quite a show," said co-author Ken Amor, from the University of Oxford.
"The massive impact would have melted rocks and thrown up an enormous cloud of vapour that scattered material over a large part of the region around Ullapool. The crater was rapidly buried by sandstone which helped to preserve the evidence."
Unusual rock formations in the area were previously thought to have been formed by volcanic activity.
But Ken Amor and his colleagues from Oxford and Aberdeen found an "ejecta blanket" evidence buried in rocks from the area. This represents debris thrown out when the huge object slammed into the ground.
Ejected material from the meteorite strike is scattered over an area about 50km across, roughly centred on the northern Scottish town of Ullapool.
In the rocks, the researchers found elevated levels of the element iridium, which is characteristic of extra-terrestrial material. They also found microscopic parallel fractures that also imply a meteorite strike.
The proposed volcanic origin for the rock formations had previously been a puzzle, as there are no volcanic vents or other volcanic sediments nearby.
Co-author John Parnell, a geologist at the University of Aberdeen, said: "Building up the evidence has been painstaking, but has resulted in proof of the largest meteorite strike known in the British Isles."
(BBC)
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