A group of scientists from Canada have discovered evidence that an extraplanetary body came down over Canada about 12,900 years ago. The evidence suggests that the comet might have triggered the death of giant animals roaming North America and triggered a cooling spell in the Earth's climate. Scientists say that during the Younger Dryas climatic period temperatures fell sharply.
During the Younger Dryas period, temperatures in parts of the northern hemisphere dropped to about 5°C within a decade or less. Scientists say that the effects of that climatic change lasted for over 1000 years before temperatures began to warm again. The scientists believe that this climate change and the resulting animal extinction is the reason that North America lost some of the huge animals that roamed such as sabertooth cats and others.
The climatic change is also believed to be a major reason humans shifted from hunter-gatherer to agriculture. The prevailing theory as to what caused the Younger Dryas is the draining of Lake Agassiz, which was a vast freshwater lake the size of the black sea. The theory suggests that glaciers dammed the lake and when it drained lots of fresh water flowed into the Atlantic and Arctic seas disrupting warming sea currents.
However, an alternate theory has now surfaced suggesting that the continent could've undergone a series of impacts from comets or asteroids that triggered the cooling period. Scientists discovered a massive 4 km wide crater from around the Younger Dryas period in Canada already. The scientists also found evidence of another direct and massive impact. Concentrations of spherules, which are crystalline rocks formed with temperatures above 2000°C, were discovered all along the eastern seaboard. Those spherules can only be caused by volcanoes or massive impacts.
"It definitely came down in Quebec," Professor Mukul Sharma said. "The spherules that we found have iridium isotope signals which are consistent with a derivation from this area, just north of the St. Lawrence river."
SOURCE: The Register