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Photos The Evidence, Up Close
The chemical composition of the yellow spheres revealed them to be Earth rocks. That meant there was only one likely way they could have been created -- in the heat of an impact, which flung melted rock into space and then rained back down, cooling and solidifying into spheres while in free fall. The discovery was written up and reported in the April issue of the journal Geology. The analysis of the microtektites revealed they are similar enough in appearance, composition and age to represent the edges of the Australasian strewnfield, said Folco. That strewnfield already had been found to extend from the Indian Ocean to the Pacific. "It's a pretty big strewn field," said tektite pioneer and professor emeritus Bill Glass of the University of Delaware. Larger tektites from the impact have been found all over Australia and smaller microtektites have been extracted from the bottom of the Indian Ocean, he told Discovery News. But this is the first good evidence that the debris might have been flung even further, he explained. "You'd think that something that big would be easy to find," said Glass. "It's a real puzzle." The most likely location of the hidden crater is somewhere in Indochina, said Glass. One possibility is that the meteor struck down on what is the sea floor today. But 800,000 years ago, an ice age would have lowered the sea level and exposed the seafloor. Since then it could have been buried by marine sediments. Related Links: Larry O'Hanlon's blog: Earth Impacts |
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