GEOARCHAEOLOGY OF THE 12.9ka IMPACT HYPOTHESIS

An hypothesized extraterrestrial impact in North America at ~12.9ka has been proposed as causing Younger Dryas climate changes, terminal Pleistocene mammalian extinctions, and a supposedly heretofore unexplained "termination" of the Clovis archaeological culture. However, an examination of archaeological, geochronological and stratigraphic evidence fails to provide evidence of a demographic collapse of post-Clovis human populations, especially where the Clovis and post-Clovis site records are reasonably well-constrained chronologically. Although few Clovis sites contain evidence of an immediate post-Clovis occupation, interpreting that absence as population collapse is likewise problematic since the great majority of later Paleoindian localities also lack immediately succeeding occupations. Where multiple occupations do occur, stratigraphic hiatuses between them are readily explained by geomorphic processes. Furthermore, calibrated radiocarbon ages demonstrate continuous occupation across the time of the purported "YD event." And, finally, the relatively few sites purported to provide direct evidence of the 12.9 ka impact are not well constrained to that time. An ET impact is an unnecessary ‘solution’ for an archaeological problem that does not exist. That issue is also independent of whether there was an extraterrestrial impact at 12.9 ka, the demonstration of which can only be made with evidence from the geological record.