terça-feira, 12 de junho de 2012

Meteorite storm 'smashed the Earth 12,000 years ago and killed off a prehistoric people'

Scientists find 'melt-glass' in 12,000-year-old rock
Melt glass forms at 1,700 degrees - equal to atomic bomb
Meteorites thought to have triggered a cold snap that killed off early civilisation and giant animals

Scientists have found compelling evidence that a meteorite storm hit the earth more than 12,000 years ago, and is likely to have been responsible for the extinction of a prehistoric people and giant animals including mammoths.

Evidence of the meteorite’s intense heat was found on two continents. The researchers believe the huge cosmic impact triggered a vicious cold snap, which caused widespread destruction.

The international team found a substance known as melt glass, which forms at temperatures of 1,7000 to 2,200 degrees Celcius and can result from a ‘cosmic body’ hitting the earth.

Extreme heat: The meteorite impact caused the 13,000-year-old quartz found in Syria to melt and boil, creating features including burst bubbles and flow textures

The material was found in a thin layer of rock in Pennsylvania and South Carolina in the US, along with Syria. Tests confirmed the material was not of cosmic, volcanic or human-made origin.


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‘The extreme temperatures required are equal to those of an atomic bomb blast, high enough to make sand melt and boil,’ said James Kennett, professor of earth science at UC Santa Barbara.

The melt-glass appears identical to other material found in Meteor Crater in Arizona, and the Australasian tektite field, and also matches melt-glass produced by the 1945 Trinity nuclear airburst in New Mexico in the US, Professor Kennett said.

Gone forever: The meteor storm is thought to have caused the mass extinction of megafauna including the woolly mammoth
The team's findings support the controversial theory that an asteroid impact occurred 12,900 years ago and triggered the start of an unusual cold period on Earth, leading to widespread extinction of human and animal life.
In the cold period, known as the Younger Dryas, North American megafauna including mammoths and giant ground sloths disappeared forever, along with a prehistoric civilisation called the Clovis culture.
The Clovis people used distinctive bone and ivory tools and are regarded as the first human inhabitants of the New World.

Match: Melt glass, known as trinitite, formed during the Trinity nuclear airburst in New Mexico in 1945 when rocks melted. The scientists say the melt-glass is similar to that found in the 12,800-year-old rock
Evidence supporting the theory has now been found on three continents, covering nearly one-third of the planet, from California to Western Europe, and into the Middle East.
Syria is the easternmost site yet identified in the northern hemisphere, but the researchers have yet to find a limit to debris field of the impact. Melt-glass has been found in rock layers of the same age in Arizona and Venezuela.

Scientists found the melt glass - evidence of the meteorite's intense heat - in Pennsylvania and South Carolina in the US along with Syria

The three sites found in the latest study were separated by 1,000 to 10,000 kilometers, suggesting that ‘a swarm of cosmic objects,’ either fragments of a meteorite or comet, had hit the earth, Professor Kennett said.

Proof: Earth scientist James Kennett says evidence for the meteorite has been found over one third of the planet----------------->>>>>

Professor Kennett added that the archaeological site in Syria where the melt-glass material was found –– Abu Hureyra, in the Euphrates Valley –– is one of the few sites of its kind that record the transition from nomadic hunter-gatherers to farmer-hunters who live in permanent villages.

‘Archeologists and anthropologists consider this area the “birthplace of agriculture,” which occurred close to 12,900 years ago,’ Professor Kennett said.

‘The presence of a thick charcoal layer in the ancient village in Syria indicates a major fire associated with the melt-glass and impact spherules 12,900 years ago,’ he continued.

‘Evidence suggests that the effects on that settlement and its inhabitants would have been severe.’

The study was published today in the Proceedings of the National Academy of Sciences.

Fonte: Dailymail.co.uk

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