Graham Hancock has an interesting theory of a worldwide civilization that was wiped out (along with the mastodon) by a comet hitting the north american icecap during the younger dryas period around 11000 years ago.

http://www.amazon.com/Magicians-Gods-Forgotten-Wisdom-Civili...

See Graham Hancock's book, "Magicians of the Gods: The Forgotten Wisdom of Earth's Lost Civilization" (http://www.amazon.com/Magicians-Gods-Forgotten-Wisdom-Civili...) for a rebuttal to the archaeological model presented in this article.

Hancock's position is the archaeological model from this article is full of holes; created by multiple assumptions based on assumptions re: radiocarbon dating & general lack of critical thinking.

Instead he points to evidence of two comets hitting the ice caps in the last ice age (younger Dryas period), which melted the ice, causing "fire to rain" & worldwide flooding.

https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesi...

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Imo, there is too much uncertainty to commit to one historical model; yet I perceive Hancock's model to have more integrity.