Saturday, August 22, 2009

Where did the asteroid hit?

In 1990, Alan Hildebrand, a post- graduate from the University of Arizona, was put in touch will geophysicist Glen Penfield who worked for the major Mexican oil company Petroleos Mexicanos (PEMEX). Penfield believed that he had discovered a potential impact crater site. While looking over the old survey data from PEMEX for the Yucatán region of Mexico, Penfield noticed a huge buried arc of rock. He was excited to find that the 1960s gravity maps of the region revealed another arc, which fitted together with the first to form a huge circle. Deep beneath the little Mexican village of Puerto Chixulub at the tip of the Yucután peninsular, Penfield had found a crater over 100 miles wide, one of the largest impact structures on Earth.
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Penfield was aware that 50 years ago, PEMEX had been in the Yucután region looking for oil. Whilst digging an exploratory well, the workers had come across an unusual layer of igneous volcanic rock called andesite. Together, Hildebrand and Penfield re-examined the samples of andesite PEMEX had collected. Their analysis revealed that the rock contained shock- metamorphosized minerals, further evidence supporting their hypothesis that the Chixulub crater was the K-T impact site. The consensus of the scientific community is that this faded scar bears the mark of the most devastating impact the Earth has ever seen.
So it was 65 million years ago that a 2.6 billion ton asteroid the size of Mount Everest fell from the sky at 40,000 miles per hour. It slammed into the lagoons of New Mexico with the energy of 100 million megatons of dynamite, 200 times more powerful than the biggest nuclear bomb ever detonated on Earth.
A superheated shockwave rushed out from the impact faster than the speed of sound. The crash conjured ferocious fires and raised tsunamis around the Gulf of Mexico. The Earth trembled, volcanoes erupted and hurricane winds ripped through the air. Trillions of tons of debris were thrown up into the atmosphere, hurling down glowing fireballs on the Earth for hundreds of miles around.

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