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The settlement occupants left an abundant and continuous record of seeds, legumes and other foods...By studying these archaeological layers, Professor Kennett and colleagues were able to discern the types of plants that were being collected in the warmer, humid days before the climate changed and in the cooler, drier days after the onset of what we know now as the Younger Dryas cool period.Before the impact, the inhabitants' prehistoric diet involved wild legumes and wild-type grains, and small but significant amounts of wild fruits and berries.In the layers corresponding to the time after cooling, fruits and berries disappeared and their...

Asteroid Day this year, June 30, 2021, is 113 years after the Tunguska impact event in Siberia, which destroyed an area of pristine forest the size of Tokyo. With blasted and burnt tree trunks leveled and stripped bare over such a vast area, it is as though a large atomic bomb had been dropped on the forest. The debate still goes on in the research literature, but a popular theory is that this impact was caused by a small comet fragment, in the region of 328 feet (100 meters) in diameter, that exploded at an altitude of around 5 miles...

We report the discovery in Lake Cuitzeo in central Mexico of a black, carbon-rich, lacustrine layer, containing nanodiamonds, microspherules, and other unusual materials that date to the early Younger Dryas and are interpreted to result from an extraterrestrial impact. These proxies were found in a 27-m-long core as part of an interdisciplinary effort to extract a paleoclimate record back through the previous interglacial. Our attention focused early on an anomalous, 10-cm-thick, carbon-rich layer at a depth of 2.8 m that dates to 12.9 ka and coincides with a suite of anomalous coeval environmental and biotic changes independently recognized in other...

(Abstract only) Significance We present detailed geochemical and morphological analyses of nearly 700 spherules from 18 sites in support of a major cosmic impact at the onset of the Younger Dryas episode (12.8 ka). The impact distributed ∼10 million tonnes of melted spherules over 50 million square kilometers on four continents. Origins of the spherules by volcanism, anthropogenesis, authigenesis, lightning, and meteoritic ablation are rejected on geochemical and morphological grounds. The spherules closely resemble known impact materials derived from surficial sediments melted at temperatures >2,200 °C. The spherules correlate with abundances of associated melt-glass, nanodiamonds, carbon spherules, aciniform carbon, charcoal,...

A controversial theory that suggests an extraterrestrial body crashing to Earth almost 13,000 years ago caused the extinction of many large animals and a probable population decline in early humans is gaining traction from research sites around the world. The Younger Dryas Impact Hypothesis, controversial from the time it was presented in 2007, proposes that an asteroid or comet hit the Earth about 12,800 years ago causing a period of extreme cooling that contributed to extinctions of more than 35 species of megafauna including giant sloths, sabre-tooth cats, mastodons and mammoths. It also coincides with a serious decline in early...