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L

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RE: Chicxulub event
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But Keller and Addate worried that we were misreading both the geologic and fossil records. They conducted surveys at numerous sites in Mexico, including a spot called El Peñón, near the impact crater. They were especially interested in a 30-ft. layer of sediment just above the iridium layer. That sediment, they calculate, was laid down at a rate of about 0.8 in. to 1.2 in. per thousand years, meaning that all 30 feet took 300,000 years to settle into place.
Analysing the fossils at this small site, they counted 52 distinct species just below the iridium layer. Then they counted the species above it. The result: the same 52. It wasn't until they sampled 30 feet higher - and 300,000 years later - that they saw the die-offs.

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The theory that dinosaurs were wiped out by an asteroid 65million years ago has been challenged.

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The demise of the dinosaurs probably occurred 300,000 years after a giant meteor struck what is now Mexico, scientists said, casting doubt on a popular theory that the impact triggered a mass extinction.
The Chicxulub crater, which is about 180 kilometres  across, was formed on the Yucatan peninsula when an extra-terrestrial object struck Earth 65 million years ago. Since its discovery in 1978, the crater has been cited as evidence that the impacts aftermath led to the extinction of about 65 percent of all species including the dinosaurs.


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The impact of a huge meteorite at the end of the Cretaceous period 65 million years ago is generally held responsible for the sudden demise of 60-80% of all species on Earth. But new results challenge the common idea that the extinctions were partly caused by global wildfires triggered by the violent impact.
Claire Belcher and colleagues at Royal Holloway University of London in Surrey, UK, say in a paper in the Proceedings of the National Academy of Sciences USA that the widespread soot deposits in sedimentary rocks formed at the time of the putative impact are not, as previously asserted, evidence of runaway fires caused by the meteorite's impact.

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Geologist Honoured for Earth-Shaking Discovery
A University of California Berkeley professor is being honoured for his theory that a giant meteor wiped out dinosaurs and many other forms of life millions of years ago.

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Geologist Who Linked Cosmic Strike to Dinosaurs' Extinction Takes Top Prize
Walter Alvarez, the maverick geologist who convinced a skeptical world that dinosaurs and many other living things on Earth were wiped out by a huge fireball from space, has won the highly esteemed Vetlesen Prize. Considered by many the earth sciences equivalent of a Nobel, the $250,000 award is funded by the New York-based G. Unger Vetlesen Foundation and administered by Lamont-Doherty Earth Observatory, a member of Columbia Universitys Earth Institute.

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A prehistoric crater left by an asteroid collision in Mexico's Yucatan Peninsula could yield clues about what Mars was like billions of years ago, a NASA scientist says.
NASA planetary geologist Adriana Ocampo is digging up rocks buried deep under southeastern Mexico for hints about what impact craters can reveal about planet formation, and says her work could shed light on a giant crater on the surface of Mars.

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L

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The Chicxulub crater
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NASA is advocating that the Mexican zone of Chicxulub, where 65 million years ago a large meteorite impacted, changing the course of evolution on Earth, be declared a World Heritage Site by UNESCO.

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L

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RE: Chicxulub event
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Scientists have developed a new way of determining the size and frequency of meteorites that have collided with Earth.  Their work shows that the size of the meteorite that likely plummeted to Earth at the time of the Cretaceous-Tertiary (K-T) boundary 65 million years ago was 2.5 to 4 miles in diameter.  The meteorite was the trigger, scientists believe, for the mass extinction of dinosaurs and other life forms.

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L

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It's a cratered spheroid, just the kind of object one imagines striking the Earth about 65 million years ago and wiping out 70 per cent of the planet's species -- including the dinosaurs.

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