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A cosmic crash in Canada approximately 12,900 years ago triggered prehistoric climate change, says a study conducted by researchers at Dartmouth College.
The cosmic crash that happened at the start of the Younger Dryas period indicates a sudden global change to a colder, dry climate with widespread impacts on both animals and humans.
The cosmic impact also may have prompted human hunters to begin gathering and growing their food.
According to the researchers, the crash wiped out many of Earth’s large mammals, including camels, giant sloths, saber-toothed cats and mastodons.
In North America, for example, the large animals all disappeared, including mastodons, camels, giant ground sloths and saber-toothed cats. As a result, the Clovis people put down their big-game spears and began gathering roots and berries, as well as hunting smaller game.
“The Younger Dryas cooling impacted human history in a profound manner,” says co-author Mukul Sharma, a professor at Dartmouth College. “Environmental stresses may also have caused Natufians in the Near East to settle down for the first time and pursue agriculture.”
How the crash happened?
While there is no controversy over whether or not these environmental changes took place, the cause of these changes has long been disputed.
Although many scientists agree on the fact that these environmental alterations took place, there has been heated debate over the cause of these changes.
The traditional view of the Younger Dryas cooling episode has been that an ice dam in the North American ice sheet broke open, sending a huge amount of freshwater into the Atlantic Ocean. The rapid arrival of freshwater is believed to have stopped the ocean currents that transport tropical water northward, leading to the cold, dry climate of the Younger Dryas.
However, the researchers have found definite evidence connecting a cosmic crash with this climate alteration. The research looked at spherules, or droplets of solidified molten rock discharged by the impact of a cosmic crash. These particular spherules were obtained from Younger Dryas boundary layers at locations in Pennsylvania and New Jersey. According to the researchers, the geochemistry and mineralogy features of the spherules are the same as rock discovered in southern Quebec, where the researchers think the cosmic crash occurred.
“We have for the first time narrowed down the region where a Younger Dryas impact did take place,” notes Sharma, “even though we have not yet found its crater.”
The study’s findings are described in detail in the journal Proceedings of the National Academy of Science.