asteroid

Researchers say that a cosmic impact thought to have contributed to the demise of the mammoths never actually happened.

About 13,000 years ago, our planet got really cold and it stayed that way for about a millenium. Known as the Younger Dryas, this cold snap coincided with the demise of the mammoths, as well as the disappearance of America’s Clovis culture. But what caused it?

One controversial theory put forward in the 1980s argued that the icy temperatures were triggered when a comet or a meteorite struck North America. But University of California-Davis scientists disagree.

In a paper recently published online in the Journal of Archaeological Science, specialist Peter Thy and fellow researchers analyzed siliceous scoria droplets – porous granules associated with melting – from four sites in northern Syria dating back 10,000 to 13,000 years ago. The results, they explain, discredit this decades-old theory.

Debunking a decades-old theory

The researchers compared some of the rock soil droplets they took from Syria, which they believed to have formed by heating, with others previously argued to have been created by the cosmic impact that led to the Younger Dryas cold period.

What they found was that the composition of the droplets they found in their samples was related to local soils, rather than soils from the continent of impact, as one would expect of the aftermath a massive meteorite whose impact was so massive it affected all continents.

Even more tellingly, researchers say the makeup of the droplets shows that they were formed by short-lived heating events of modest temperatures, and not by the intense, high temperatures expected from a large impact event. Add to this the fact that the droplets greatly varied in terms of their age (from 10,000 to 13,000 years old), and the cosmic impact theory is pretty much out.

“For the Syria side, the impact theory is out. There’s no way that can be done,” said study leader Peter Thy. “If there was one cosmic impact, they should be connected by one date and not a period of 3,000 years,” he said.

OK, so where did the rock soil droplets come from?

The University of California-Davis researchers say that, rather than having been spawned by a disastrous comet or meteorite strike, the rock soil droplets previously argued to be evidence of a cosmic impact that occurred almost 13,000 years ago are in fact the result of Stone Age house fires.

The area of study in Syria was associated with early agricultural settlements along the Euphrates River. Most of the locations include mud-brick structures, some of which show signs of intense fire and melting. The study concludes that the scoria formed when the buildings, made of a mix of local soil and straw, were burned to the ground.
Source: Eurekalert

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