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a cosmic impact that caused destruction of one of the world'searliest human settlements
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https://phys.org/news/2020-03-eviden...CFrHpFhYJQuuLE Researchers find evidence of a cosmic impact that caused destruction of one of the world's earliest human settlements by Sonia Fernandez, University of California - Santa Barbara Location of Abu Hureyra (adapted from Moore et al.. (a) Map of the Middle East, showing Abu Hureyra location (AH) in Syria. (b) Map of the Abu Hureyra tell, showing locations of excavation trenches labeled A-G near a back channel of Euphrates River that is now abandoned. Sediment samples from Trenches D, E, and G (blue rectangles) contain abundance peaks in YDB proxies, including spherules, nanodiamonds, meltglass, and platinum. Credit: Scientific Reports (2020). DOI: 10.1038/s41598-020-60867-w Before the Taqba Dam impounded the Euphrates River in northern Syria in the 1970s, an archaeological site named Abu Hureyra bore witness to the moment ancient nomadic people first settled down and started cultivating crops. A large mound marks the settlement, which now lies under Lake Assad. But before the lake formed, archaeologists were able to carefully extract and describe much material, including parts of houses, food and tools—an abundance of evidence that allowed them to identify the transition to agriculture nearly 12,800 years ago. It was one of the most significant events in our Earth's cultural and environmental history. Abu Hureyra, it turns out, has another story to tell. Found among the cereals and grains and splashed on early building material and animal bones was meltglass, some features of which suggest it was formed at extremely high temperatures—far higher than what humans could achieve at the time—or that could be attributed to fire, lighting or volcanism. "To help with perspective, such high temperatures would completely melt an automobile in less than a minute," said James Kennett, a UC Santa Barbara emeritus professor of geology. Such intensity, he added, could only have resulted from an extremely violent, high-energy, high-velocity phenomenon, something on the order of a cosmic impact. Based on materials collected before the site was flooded, Kennett and his colleagues contend Abu Hureyra is the first site to document the direct effects of a fragmented comet on a human settlement. These fragments are all part of the same comet that likely slammed into Earth and exploded in the atmosphere at the end of the Pleistocene epoch, according to Kennett. This impact contributed to the extinction of most large animals, including mammoths, and American horses and camels; the disappearance of the North American Clovis culture; and to the abrupt onset of the end-glacial Younger Dryas cooling episode. The team's findings are highlighted in a paper published in the Nature journal Scientific Reports. "Our new discoveries represent much more powerful evidence for very high temperatures that could only be associated with a cosmic impact," said Kennett, who with his colleagues first reported evidence of such an event in the region in 2012. Abu Hureyra lies at the easternmost sector of what is known as the Younger Dryas Boundary (YDB) strewnfield, which encompasses about 30 other sites in the Americas, Europe and parts of the Middle East. These sites hold evidence of massive burning, including a widespread carbon-rich "black mat" layer that contains millions of nanodiamonds, high concentrations of platinum and tiny metallic spherules formed at very high temperatures. The YDB impact hypothesis has gained more traction in recent years because of many new discoveries, including a very young impact crater beneath the Hiawatha Glacier of the Greenland ice sheet, and high-temperature meltglass and other similar evidence at an archaeological site in Pilauco, located in southern Chile. "The Abu Hureyra village would have been abruptly destroyed," Kennett said. Unlike the evidence from Pilauco, which was limited to human butchering of large animals up to but not younger than the YDB impact burn layer, Abu Hureyra shows direct evidence of the disaster on this early human settlement. An impact or an airburst must have occurred sufficiently close to send massive heat and molten glass over the entire early village, Kennett noted. The glass was analyzed for geochemical composition, shape, structure, formation temperature, magnetic characteristics and water content. Results from the analysis showed that it formed at very high temperatures and included minerals rich in chromium, iron, nickel, sulfides, titanium and even platinum- and iridium-rich melted iron—all of which formed in temperatures higher than 2200 degrees Celsius. "The critical materials are extremely rare under normal temperatures, but are commonly found during impact events," Kennett said. According to the study, the meltglass was formed "from the nearly instantaneous melting and vaporization of regional biomass, soils and floodplain deposits, followed by instantaneous cooling." Additionally, because the materials found are consistent with those found in the YDB layers at the other sites across the world, it's likely that they resulted from a fragmented comet, as opposed to impacts caused by individual comets or asteroids. "A single major asteroid impact would not have caused such widely scattered materials like those discovered at Abu Hureyra," Kennett said. "The largest cometary debris clusters are proposed to be capable of causing thousands of airbursts within a span of minutes across one entire hemisphere of Earth. The YDB hypothesis proposed this mechanism to account for the widely dispersed coeval materials across more than 14,000 kilometers of the Northern and Southern Hemispheres. Our Abu Hureyra discoveries strongly support a major impact event from such a fragmented comet." Explore further -------------------------- Geologic evidence supports theory that major cosmic impact event occurred approximately 12,800 years ago -------------------------- More information: Andrew M. T. Moore et al. Evidence of Cosmic Impact at Abu Hureyra, Syria at the Younger Dryas Onset (~12.8 ka): High-temperature melting at 2200 °C, Scientific Reports (2020). DOI: 10.1038/s41598-020-60867-w Journal information: Scientific Reports Provided by University of California - Santa Barbara |
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a cosmic impact that caused destruction of one of the world'searliest human settlements
On 3/10/2020 8:54 AM, a425couple wrote:
from https://phys.org/news/2020-03-eviden...CFrHpFhYJQuuLE Researchers find evidence of a cosmic impact that caused destruction of one of the world's earliest human settlements by Sonia Fernandez, University of California - Santa Barbara Location of Abu Hureyra (adapted from Moore et al.. (a) Map of the Middle East, showing Abu Hureyra location (AH) in Syria. (I'm frustrated at the recent releases of theories of asteroid impacts,,, more specifically that one hit about 13,000 years ago. Some think it was like here, in Syria. Others that it was in Greenland. And others are claiming that it was in southern Chile. Ohhh Well! Here is another about the Syrian area.) from https://www.foxnews.com/science/gian..._XQW2BnUT_rYuc Giant asteroid apocalypse 13K years ago was witnessed by ancient humans, experts believe By Chris Ciaccia | Fox News The asteroid that hit Earth nearly 13,000 years ago and ended the Pleistocene era likely wiped out an ancient civilization in what is modern-day Syria, according to newly discovered evidence. The research, published in Scientific Reports, notes that experts discovered remnants of glass that were created during a high-impact event, as well as minerals such as chromium, iron, nickel and others, all of which formed in temperatures higher than 2,200 degrees Celsius, according to a statement from the University of California-Santa Barbara. “To help with perspective, such high temperatures would completely melt an automobile in less than a minute,” said one of the study's co-authors and UC Santa Barbara emeritus professor of geology James Kennett in the statement. (Credit: University of California Santa Barbara) (Credit: University of California Santa Barbara) The discovery was made at a site known as Abu Hureyra, which was abandoned roughly 5,000 years ago. Known as the Pleistocene Epoch, the most recent ice age is generally defined as starting 2.6 million years ago and ending approximately 11,700 years ago The glass is believed to have formed “from the nearly instantaneous melting and vaporization of regional biomass, soils and floodplain deposits, followed by instantaneous cooling," according to the study. Kennett added that the materials found are "extremely rare" under normal temperatures, but common during impact events. A "single, major asteroid impact" could not have caused the widely scattered material discovered at Abu Hureyra and that it was more likely a fragmented comet, the researcher said. “The largest cometary debris clusters are proposed to be capable of causing thousands of airbursts within a span of minutes across one entire hemisphere of Earth," Kennett explained. "The [Younger Dryas Boundary] hypothesis proposed this mechanism to account for the widely dispersed coeval materials across more than 14,000 kilometers [8,700 miles] of the Northern and Southern Hemispheres. Our Abu Hureyra discoveries strongly support a major impact event from such a fragmented comet.” Previous studies have focused on the Younger Dryas event, a period that saw the extinction of species such as woolly mammoths, bison and giant sloths, causing global consequences. In October 2019, a study was published that said a brief ice age period occurred roughly 12,800 years ago and was caused by an asteroid impact, after researchers found high levels of iridium and platinum in White Pond near Elgin, S.C. An enormous crater, first discovered in 2015 but not officially verified until November 2018, left a 19-mile crater in Greenland and may have caused the disappearance of the Clovis people, a mysterious prehistoric group that vanished without a trace, according to The Sun. According to NASA, the massive hole is "one of the 25 largest impact craters on Earth" and is said to have "rocked the Northern Hemisphere." Follow Chris Ciaccia on Twitter @Chris_Ciaccia |
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