The idea that a comet blasted into eastern North America about 10,900 years ago has been receiving a lot of media attention lately. The explosion, which is said to have been equivalent to a 100-million-megaton bomb, supposedly caused the extinction of the giant mammals of the ice age as well as the people who lived then. R.B. Firestone of the Lawrence Berkeley National Laboratory and numerous co-authors presented the basic argument in an article in the Proceedings of the National Academy of Sciences in 2007. Since then, other research has cast considerable doubt on the claim.
     Most recently, J.P. Marlon, a geographer at the University of Oregon, and several co-authors dispute the claim of a single, catastrophic event that triggered the ice-age extinctions. Their paper, which appears in the current Proceedings of the National Academy of Sciences, makes it clear there is no evidence for continent-wide forest fires in the aftermath of the supposed comet impact. Firestone and colleagues also asserted that the comet impact hypothesis explained the mysterious disappearance of the Clovis culture. From an archaeological perspective, however, the Clovis culture didn't vanish - mysteriously or otherwise.
     In the centuries after the supposed comet impact, Paleoindian groups clearly related to the Clovis culture continued to thrive in eastern North America.
The Debert site in Nova Scotia and the Parkhill site in southern Ontario are examples of large, thriving post-Clovis communities sustained by hunting herds of caribou that also appear to have been doing just fine in spite of living at what would have been very near ground zero. The Clovis culture adapted to changing environments across North America, and the descendants of these people adopted diverse ways of life that archaeologists eventually would come to recognize with different names. Those different names, however, do not imply that the parent culture disappeared or that a catastrophe is required to explain the transition from Clovis to later cultures.

Source: The Columbus Dispatch (3 March 2009)