Proposal that a comet or asteroid struck or exploded over the northern hemisphere about 12,900 years ago, triggering the Younger Dryas cold reversal, the collapse of the North American megafauna and the end of the Clovis archaeological horizon. Put forward by Richard Firestone and colleagues in the Proceedings of the National Academy of Sciences in 2007, it rests on claimed impact markers in the boundary layer: magnetic microspherules, nanodiamonds, carbon spherules, and a platinum anomaly reported from Greenland ice in 2013. Independent attempts to reproduce those markers have repeatedly failed or found them in the wrong layers, and critics including Vance Holliday argue that the chronology does not hold across sites. It remains a live minority position in the literature rather than a settled result. Graham Hancock adopted it in Magicians of the Gods (2015) as the replacement for Earth-Crust Displacement, which is a change of mechanism rather than a change of conclusion.
Connections
Earth-Crust Displacement · Graham Hancock · Ancient Apocalypse