Is this what killed off the Clovis culture?

[Sunlei]

5. another good article!

A 1.5-kilometer asteroid, intact or in pieces, may have smashed into an ice sheet just 13,000 years ago.
IMAGE: NASA SCIENTIFIC VISUALIZATION STUDIO

A large asteroid struck Greenland in the time of humans. How did it affect the planet?

....impact would have been a spectacle for anyone within 500 kilometers. A white fireball four times larger and three times brighter than the sun would have streaked across the sky.

If the object struck an ice sheet, it would have tunneled through to the bedrock, vaporizing water and stone alike in a flash.

The resulting explosion packed the energy of 700 1-megaton nuclear bombs, and even an observer hundreds of kilometers away would have experienced a buffeting shock wave, a monstrous thunderclap, and hurricane-force winds.

Later, rock debris might have rained down on North America and Europe, and the released steam, a greenhouse gas, could have locally warmed Greenland, melting even more ice.......

http://science.sciencemag.org/content/362/6416/738