Archaeologists have found evidence from the Topper
site in South Carolina, USA, that Clovis populations here went
through a population collapse at the time of the proposed ice age
But there is no evidence of a similar decline in
other parts of the continent. The Clovis culture does vanish from
the archaeological record abruptly, but it is replaced by a myriad
local hunter-gatherer cultures.
Jeff Severinghaus, a palaeoclimatologist at Scripps
Institution of Oceanography in California, told Nature magazine that
the impact theory shouldn't be dismissed; it deserved further
investigation. According to the new idea, the comet would have caused
widespread melting of the North American ice sheet. The waters would
have poured into the Atlantic, disrupting its currents.
This, the scientists said, could have caused the
thousand-year-long Younger Dryas cold spell, which also affected Asia
and Europe. The Younger Dryas has been linked by some researchers to
changes in the living patterns of people living in the Middle East -
coincidentally or otherwise the beginning of farming is noted very
soon after this period.
While unproven, the 'space rock' idea is not without
some support in known fact. A massive explosion near the Tunguska river,
Siberia, in 1908, is also thought to have been caused by a space rock
exploding in the atmosphere. It felled eighty million trees over an
area of two thousand square kilometres.