The Younger Dryas was an abrupt period of cold and drought between about 12,800 and 11,500 years ago associated with Mammoth extinction, possibly with the extinction of the Clovis culture.
Temperature drop during the Younger Dryas.
New evidence indicates it was caused by either a meteorite impact or comet's close pass.
Something -- global-scale combustion caused by a comet scraping our planet's atmosphere or a meteorite slamming into its surface -- scorched the air, melted bedrock and altered the course of Earth's history.
Four kinds of evidence scattered across several continents are conclusive. Impact spherules are the main evidence.
Tankersley explains what he and a team of international researchers found may have caused this catastrophic event in Earth's history in their research, "Evidence for Deposition of 10 Million Tonnes of Impact Spherules Across Four Continents 12,800 Years Ago," which was published in the Proceedings of the National Academy of Sciences.
This research might indicate that it wasn't the cosmic collision that extinguished the mammoths and other species, Tankersley says, but the drastic change to their environment.
"The climate changed rapidly and profoundly. And coinciding with this very rapid global climate change was mass extinctions." [emphasis mine]
Other important findings include:
Micrometeorites: smaller pieces of meteorites or particles of cosmic dust that have made contact with Earth's surface.
Nanodiamonds: microscopic diamonds formed when a carbon source is subjected to an extreme impact, often found in meteorite craters.
Lonsdaleite: a rare type of diamond, also called a hexagonal diamond, only found in non-terrestrial areas such as meteorite craters.
Impact spherules, magnified.
This is where they were found.
Imagine the consequences an identical event in today's world. Impact events are clearly part of our history.
It's interesting that, according to the chart, the temperature and ice accumulation briefly went back up after the Younger Dryas, but then went back down to where they were during that period. I wonder why?