A cosmic explosion may have devastated a vast Native American culture 1,500 years ago
More than 1500 years ago, a vast culture known as the Hopewell tradition (or the Hopewell culture) spanned what is now the eastern United States.
The cause of the culture’s decline has long been debated, with war and climate change being two of the possibilities, but now a new avenue of investigation has opened up: debris from a near-Earth comet.
Researchers working at 11 different Hopewell archaeological sites spanning three states have found unusual concentrations of iridium and platinum in their excavations – telltale signs of meteorite fragments. Meanwhile, a layer of charcoal in the sediment suggests an intense period of high heat.
The hypothesis is that debris from a passing comet may have struck near Ohio Hopewell communities, causing an explosion that would have profound and potentially devastating effects on the local environment.
Signs that people collected fragments of meteorites and incorporated them into their jewelry and instruments, as well as hints of a calamity in local folklore, suggest that there must have been an important event – an event that, according to the researchers, may have contributed to a significant upheaval in the social sphere. .
There are other clues, too: The Hopewells built a comet-shaped mound near the epicenter of the meteor shower region, which is now called Milford Earthworks. Moreover, a calamitous event that goes back a long way in history is still spoken of today among the descending tribes.
“The Miami tells the story of a horned serpent that flew through the sky and dropped rocks to earth before plunging into the river”, says anthropologist Kenneth Tankersley from the University of Cincinnati in Ohio. “When you see a comet streak through the air, it looks like a big snake.”
“The Shawnees refer to a ‘sky panther’ who had the power to destroy forests. The Ottawas tell of a day when the Sun fell from the sky. And when a comet hit the thermosphere, it would have exploded like a nuclear bomb. “
Micrometeorites left behind from such events can reveal a chemical fingerprint, researchers say.
“Cosmic events like asteroids and comet explosions leave behind large amounts of a rare element known as platinum,” Tankersley says.
“The problem is that platinum also occurs in volcanic eruptions. So we’re also looking for another rare element found in non-terrestrial events such as meteor impact craters: iridium. And we found a peak at both in iridium and platinum.”
The team used techniques such as scanning electron microscopy and energy dispersive spectrometry to identify elements in the sediments they collected. The meteorite fragments were unusually highly concentrated compared to other locations and times.
At the same time, the material was also dated using radiocarbon and typological dating. Scholars estimate that the event took place between 252 CE and 383 CE. Historical records show that 69 near-Earth comets have been documented during the same period.
The explosion from space would have started fires covering some 9,200 square miles (some 23,828 square kilometers), according to this latest study.
Further studies are now planned to get a better idea of how the meteor shower may have impacted such a large area. The botanical landscape of the time can be analyzed by careful observation of the pollen trapped in the sediments, for example.
However, scientists admit that there are still many unanswered questions – traversing 1,500 years of history is not particularly easy. There is still much to explore in these special places during this special time.
“It is difficult to know exactly what happened” says paleoecologist David Lentz from the University of Cincinnati. “We only have a few points of light in the dark. But we have this area of high heat that would have been catastrophic for people in that area and beyond.”
The research has been published in Scientific reports.