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A long-running scientific debate over the fate of the mammoths is gaining fresh momentum, as new research adds weight to the idea that a massive cosmic event disrupted life on Earth nearly 13,000 years ago. Some scientists now believe that fragments of a disintegrating comet exploded in the atmosphere above North America, setting off a chain reaction that may have contributed to the extinction of mammoths, mastodons and other large Ice Age animals and possibly the disappearance of one of the continent’s earliest human cultures.
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In a study published in PLOS Onea research team led by UC Santa Barbara emeritus earth scientist James Kennett reports new findings from three well-known archaeological sites linked to the Clovis culture. The locations – Murray Springs in Arizona, Blackwater Draw in New Mexico and Arlington Canyon on California’s Channel Islands – have long been central to discussions about North America’s late Ice Age extinctions. At all three sites, the researchers discovered microscopic grains of “shocked” quartz, a material typically associated with extreme heat and pressure.
Kennett notes that these sites played a key role in documenting both the sudden loss of Ice Age megafauna and the disappearance of Clovis tools from the archaeological record. The new evidence, he says, strengthens the argument that a single catastrophic event may link both phenomena.
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The timing of those disappearances closely aligns with the beginning of the Younger Dryas, a puzzling climatic episode marked by an abrupt return to near-glacial conditions. Lasting roughly a thousand years, the Younger Dryas interrupted the gradual warming that followed the end of the last Ice Age and has long challenged climate scientists looking for a clear cause.
Younger Dryas impact hypothesis
The Younger Dryas impact hypothesis, which postulates that pieces of a massive comet exploded in Earth’s atmosphere, producing airbursts that released a substantial amount of energy, is one theory put forth to explain climate changes during the Younger Dryas. Scientists argue that widespread fires, shockwaves, and the release of dust and soot into the atmosphere could have resulted in the drastic cooling of the climate.
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Evidence for this theory has grown over the past 20 years, most notably the existence of a carbon-rich sediment layer known as the “black mat”, which is found in North America and Europe and is indicative of extensive burning. Further support comes from high concentrations of platinum, iridium, nanodiamonds, metallic spherules, and glassy residues created when minerals melt under extreme heat.
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Advanced imaging techniques reveal internal fractures in quartz grains, indicating exposure to harsh environments unrelated to human or volcanic activity. The discovery of shocked quartz is particularly compelling. This is crucial because atmospheric explosions can cause substantial damage without leaving a long-lasting geological imprint, and there isn’t a large impact crater from that era. Computer simulations suggest that the shock patterns observed in the quartz could be caused by low-altitude airbursts without leaving visible craters.
When considered collectively, these findings bolster the argument for a sudden, catastrophic event at the beginning of the Younger Dryas, suggesting that a cosmic airburst may have had a significant effect on ecosystems and human societies, ending the mammoth era abruptly.
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