Thursday, August 18, 2005

Are volcacoes responsible of the end of dinosaurs?

Volcanic eruptions may have triggered the demise of the dinosaurs.

Many scientists believed that an asteroid caused the mass extinction 65 million years ago. However, a new study points to a more complex event that began with a series of eruptions which took place in what is now north-western India. The Deccan Traps in Maharashtra state are flows of lava resulting from huge outpourings of molten rock and ash. A mile deep, they cover about 200,000 square miles. Vulcanologists have long thought the eruption, dated to about 65 million years ago, could have caused the extinction.

However, the Deccan Traps resulted from a series of eruptions that occurred over perhaps a million years. This would have given the global climate plenty of time to adjust. But the study shows a major part of the eruption occurred over a short period.

Scientists from the Institut de Physique du Globe de Pariscalculated that at least 2,000ft of lava was deposited in 30,000 years, which could have greatly altered global climate. They have also shown that the Traps were erupting when the asteroid crashed into what is now Mexico. This was a spectacular and almost unprecedented double whammy for Earth.

Mike Widdowson, a vulcanologist, said it seems the end of the dinosaurs may have begun with climate change brought about by the eruptions and ended with the asteroid. "The eruptions pre-conditioned the global environment toward a catastrophic tipping point before the impact occurred. The asteroid was the coup de grĂ¢ce," he said.

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