Fwd: Largest ever field of impact craters unco vered | New Scientist
- Largest ever field of impact craters uncovered
07 November 04
Exclusive from New Scientist Print Edition.
The discovery of the largest field of impact craters ever uncovered on
Earth is the first evidence that the planet suffered simultaneous meteor
impacts in the recent past. The field has gone unnoticed until now because
it is partially buried beneath the sands of the Sahara desert in
Philippe Paillou of Bordeaux University Observatory in Floirac, France,
first noticed circular geological structures in the Sahara last year,
while analysing radar satellite pictures of the area.
The structures turned out to be part of a huge field of 100 craters spread
over 5000 square kilometres near the Gilf Kebir plateau. The craters vary
in diameter from 20 metres to 2 kilometres across. The previous largest
known crater field covers a mere 60 square kilometres in Argentina.
In February, Paillou led a joint Egyptian and French mission to find the
site and examined 13 of the craters, confirming that they were the result
of simultaneous impacts. But accurately dating the field has been tricky.
Paillou estimates that it is roughly 50 million years old, relatively
young in geological terms.
The size of the field suggests that it could be the result of two or more
meteors disintegrating as they entered Earth?s atmosphere, the first
evidence of a multiple strike, he says.
"Because the field is so big, it can?t have been made by one meteor," says
Paillou. But more information is needed to understand the event and its
effects, and Paillou plans to return to the area next month.
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