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These new data are the latest to strongly support the controversialYounger Dryas Boundary (YDB) hypothesis, which proposes that acosmic impact occurred 12,900 years ago at the onset of an unusualcold climatic period called the Younger Dryas. This episodeoccurred at or close to the time of major extinction of the NorthAmerican megafauna, including mammoths and giant ground sloths; andthe disappearance of the prehistoric and widely distributed Clovisculture. The researchers' findings appear June 11 in the Proceedings of the National Academy of Sciences. "These scientists have identified three contemporaneous levelsmore than 12,000 years ago, on two continents yielding siliceousscoria-like objects (SLO's)," said H. Richard Lane, programdirector of National Science Foundation's Division of EarthSciences, which funded the research. "SLO's are indicative ofhigh-energy cosmic airbursts/impacts, bolstering the contentionthat these events induced the beginning of the Younger Dryas. Thattime was a major departure in biotic, human and climatehistory." Morphological and geochemical evidence of the melt-glass confirmsthat the material is not cosmic, volcanic, or of human-made origin."The very high temperature melt-glass appears identical tothat produced in known cosmic impact events such as Meteor Craterin Arizona, and the Australasian tektite field," said Kennett. "The melt material also matches melt-glass produced by theTrinity nuclear airburst of 1945 in Socorro, New Mexico," hecontinued. "The extreme temperatures required are equal tothose of an atomic bomb blast, high enough to make sand melt andboil." The material evidence supporting the YDB cosmic impact hypothesisspans three continents, and covers nearly one-third of the planet,from California to Western Europe, and into the Middle East. Thediscovery extends the range of evidence into Germany and Syria, theeasternmost site yet identified in the northern hemisphere. Theresearchers have yet to identify a limit to the debris field of theimpact. "Because these three sites in North America and the MiddleEast are separated by 1,000 to 10,000 kilometers, there were mostlikely three or more major impact/airburst epicenters for the YDBimpact event, likely caused by a swarm of cosmic objects that werefragments of either a meteorite or comet," said Kennett. The PNAS paper also presents examples of recent independentresearch that supports the YDB cosmic impact hypothesis, andsupports two independent groups that found melt-glass in the YDBlayers in Arizona and Venezuela. "The results strongly refutethe assertion of some critics that 'no one can replicate' the YDBevidence, or that the materials simply fell from spacenon-catastrophically," Kennett noted. He added that the archaeological site in Syria where the melt-glassmaterial was found -- Abu Hureyra, in the Euphrates Valley -- isone of the few sites of its kind that record the transition fromnomadic hunter-gatherers to farmer-hunters who live in permanentvillages. "Archeologists and anthropologists consider thisarea the 'birthplace of agriculture,' which occurred close to12,900 years ago," Kennett said. "The presence of a thick charcoal layer in the ancient villagein Syria indicates a major fire associated with the melt-glass andimpact spherules 12,900 years ago," he continued."Evidence suggests that the effects on that settlement and itsinhabitants would have been severe." Other scientists contributing to the research include Ted Bunch andJames H. Wittke of Northern Arizona University; Robert E. Hermes ofLos Alamos National Laboratory; Andrew Moore of the RochesterInstitute of Technology; James C. Weaver of Harvard University;Douglas J. Kennett of Pennsylvania State University; Paul S.DeCarli of SRI International; James L. Bischoff of the U.S.Geological Survey; Gordon C. Hillman of the University CollegeLondon; George A. Howard of Restoration Systems; David R. Kimbel ofKimstar Research; Gunther Kletetschka of Charles University inPrague, and of the Czech Academy of Science; Carl Lipo and SachikoSakai of California State University, Long Beach; Zsolt Revay ofthe Technical University of Munich in Germany; Allen West ofGeoScience Consulting; and Richard B. Firestone of LawrenceBerkeley National Laboratory. I am an expert from custompaperbagprinting.com, while we provides the quality product, such as China Custom Printed Notebook , Custom Catalog Printing, Custom Paper Bag Printing,and more.
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