Younger Dryas Impact: Civilization Reset 12,800 Years Ago

A comet impact or airburst approximately 12,800 years ago caused mass extinction and potentially destroyed an advanced pre-ice age civilization. This is one of the most evidence-rich alternative history theories.

Evidence for impact: platinum spike in geological record globally, nanodiamonds at the impact layer, sudden extinction of megafauna (mammoths, saber-tooth cats), massive flooding evidence (channeled scablands), and the anomalous age of Gobekli Tepe (11,600 BCE — far older than expected for 'primitive' peoples).

Global flood myths exist across virtually all ancient cultures. The Firestone et al. papers in peer-reviewed journals support the impact hypothesis. Graham Hancock and Randall Carlson have done extensive fieldwork correlating geological evidence with potential civilization sites.

Initial probability: 70% that the impact event happened, 40% that an advanced civilization existed before it.