Ice age not ended by Comet impact

No evidence of nanodiamonds in Younger–Dryas sediments to support an impact event

The causes of the late Pleistocene megafaunal extinctions in North America, disappearance of Clovis paleoindian lithic technology, and abrupt Younger–Dryas (YD) climate reversal of the last deglacial warming in the Northern Hemisphere remain an enigma. A controversial hypothesis proposes that one or more cometary airbursts/impacts barraged North America ≈12,900 cal yr B.P. and caused these events. Most evidence supporting this hypothesis has been discredited except for reports of nanodiamonds...

Really too bad...it was a really interesting hypotheses that the end of the last Ice age was brought on by a comet impact. There remain a great number of geographical anomalies that this tale would have neatly accounted for...not to mention the extinctions of North American megafauna and the abrupt ending of the Clovis technology.

This abstract sums it up: www.pnas.org...

As a pal said..."Stupid science!"

Originally posted by JohnnyCanuck
Really too bad...it was a really interesting hypotheses that the end of the last Ice age was brought on by a comet impact. There remain a great number of geographical anomalies that this tale would have neatly accounted for...not to mention the extinctions of North American megafauna and the abrupt ending of the Clovis technology.

The lack of nanodiamonds doesn't necessarily mean there wasn't some kind of other astronomical event that created the Younger Dryas. It just might have been more subtle, like a decrease in solar radiation caused by more sunspots or a transient cloud of interplanetary debris blocking out the sun.

The nanodiamonds are a result of shock pressure. Maybe something happened where the pressure wasn't quite enough to create diamonds along the YD boundary, but still had significant effects on the North American ice sheets, pressures along the Mid-Atlantic Ridge, and the Gulf Stream current engine. Enough to wipe out the Clovis/Atlantis people, anyway. The book has yet to be finished.