title: An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis.
abstract: Based on elevated concentrations of a set of "impact markers" at the onset of the Younger Dryas stadial from sedimentary contexts across North America, Firestone, Kennett, West, and others have argued that 12.9 ka the Earth experienced an impact by an extraterrestrial body, an event that had devastating ecological consequences for humans, plants, and animals in the New World [Firestone RB, et al. (2007) Proc. Natl. Acad. Sci. USA 104:16016-16021]. Herein, we report the results of an independent analysis of magnetic minerals and microspherules from seven sites of similar age, including two examined by Firestone et al. We were unable to reproduce any results of the Firestone et al. study and find no support for Younger Dryas extraterrestrial impact.
authors.affiliation: Department of Anthropology, University of Wyoming, Laramie, WY 82070, USA. surovell@uwyo.edu
authors.forename: Todd A
authors.initials: TA
authors.lastname: Surovell
authors.forename: Vance T
authors.initials: VT
authors.lastname: Holliday
authors.forename: Joseph A M
authors.initials: JA
authors.lastname: Gingerich
authors.forename: Caroline
authors.initials: C
authors.lastname: Ketron
authors.forename: C Vance
authors.initials: CV
authors.lastname: Haynes
authors.forename: Ilene
authors.initials: I
authors.lastname: Hilman
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Wagner
authors.forename: Eileen
authors.initials: E
authors.lastname: Johnson
authors.forename: Philippe
authors.initials: P
authors.lastname: Claeys