Uma avaliação independente da hipótese de impacto extraterrestrial de Younger Dryas

An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis

Todd A. Surovell a,1, Vance T. Holliday b, Joseph A. M. Gingerich a, Caroline Ketron a, C. Vance Haynes, Jr b, Ilene Hilman a, Daniel P. Wagner c, Eileen Johnson d and Philippe Claeys e

+ Author Affiliations

aDepartment of Anthropology, University of Wyoming, Laramie, WY 82070;

bDepartments of Anthropology and Geosciences, University of Arizona, Tucson, AZ 85721;

cGeo-Sci Consultants, Inc. , 4410 Van Buren Street, University Park, MD 20782;

dMuseum of Texas Tech University, Box 43191, Lubbock, TX 79409; and

eDepartment of Geology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium

Edited by David Jeffrey Meltzer, Southern Methodist University, Dallas, TX, and approved September 3, 2009 (received for review July 15, 2009)

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.

Clovis magnetic grains magnetic microspherules Pleistocene extinctions
Footnotes

1To whom correspondence should be addressed. E-mail: surovell@uwyo.edu

Author contributions: T.A.S. and V.T.H. designed research; T.A.S., V.T.H., J.A.M.G., C.K., C.V.H., I.H., D.P.W., E.J., and P.C. performed research; C.V.H., D.P.W., and E.J. contributed new reagents/analytic tools; T.A.S., J.A.M.G., and C.K. analyzed data; and T.A.S., V.T.H., and J.A.M.G. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

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