New evidence supports extraterrestrial impact theory
Washington: An international team of researchers has discovered melt-glass material, dating back nearly 13,000 years and forming at temperatures between 1,700 and 2,200 degrees Celsius, which was the outcome of a cosmic body hitting the earth.
The discovery was made by an 18-member international team of researchers including James Kennett, professor of earth science at University of California Santa Barbara (UCSB).
Found in a thin layer of sedimentary rock in South Carolina and Syria, the material provides the latest evidence to support the controversial Younger Dryas Boundary (YDB) hypothesis, proposing that a cosmic impact occurred 12,900 years ago at the onset of an unusual cold climatic period called the Younger Dryas.
This episode occurred at or close to the time of major extinction of the North American megafauna, including mammoths and giant ground sloths; and the disappearance of the prehistoric and widely distributed Clovis culture, the journal Proceedings of the National Academy of Sciences reports.
"These scientists have identified three contemporaneous levels more than 12,000 years ago, on two continents yielding siliceous scoria-like objects (SLOs)," said H. Richard Lane, programme director of National Science Foundation`s Division of Earth Sciences, which funded the research.
"SLOs are indicative of high-energy cosmic airbursts/impacts, bolstering the contention that these events induced the beginning of the Younger Dryas. That time was a major departure in biotic, human and climate history," said Lane.
Morphological and geochemical evidence of the melt-glass confirms that the material is not cosmic, volcanic, or of human-made origin. "The very high temperature melt-glass appears identical to that produced in known cosmic impact events such as Meteor Crater in Arizona, and the Australasian tektite field," said Kennett of UCSB, according to a California statement.
"The melt material also matches melt-glass produced by the Trinity nuclear airburst of 1945 in Socorro, New Mexico," Kennett continued. "The extreme temperatures required are equal to those of an atomic bomb blast, high enough to make sand melt and boil."
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