A meteorite might have wiped out the giant ground sloths and mammoths that once walked North America. They disappeared about 12,000 years ago. It’s possible that hunting by humans helped to hurry them on their way. But now there’s more evidence for the meteorite:
The international team of researchers looked under what is known as “black mat” sediment, which dates back to 12,900 years ago. It coincides with a period of abrupt global cooling known as the “Big Freeze,” or the Younger Dryas.
They found high concentrations of iridium, nanodiamonds, soot, charcoal and other chemicals and compounds that suggested a celestial body had crashed into the Earth and started raging, massive wildfires.
“We don’t have a smoking gun for our theory, but we sure have a lot of shell casings,” said Peter Schultz, a planetary geologist at Brown University in Rhode Island.
“Taken together, the markers found in the samples offer intriguing evidence that North America had a major impact event about 12,900 years ago.”
If the soot layer is so obvious, I’m amazed that no one has investigated it before. It’s much more obvious than other impacts which occurred longer ago.
This might explain why there is some evidence for ancient human habitation in North America, going back as far as 60,000 years, and also evidence that humans moved in about 10,000 years ago, after the most recent Ice Age. It’s too bad that the last 12,000 years of recent North American ecology and evolution, preserved so nicely for us at La Brea, was dug up and burned before anyone realized what a great science resource we had.