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Geophysical Monograph Series



  • Younger Dryas
  • extinction
  • impact
  • airburst Clovis
  • black mat
  • Nanodiamonds
  • Quaternary

Index Terms

  • 1605 Global Change: Abrupt/rapid climate change
  • 5420 Planetary Sciences: Solid Surface Planets: Impact phenomena, cratering
  • 4950 Paleoceanography: Paleoecology
  • 9350 Geographic Location: North America



Arguments and Evidence Against a Younger Dryas Impact Event

M. Boslough

Sandia National Laboratories, Albuquerque, New Mexico, USA

K. Nicoll

Department of Geography, University of Utah, Salt Lake City, Utah, USA

V. Holliday

School of Anthropology and Department of Geosciences, University of Arizona, Tucson, Arizona, USA

T. L. Daulton

Department of Physics and Center for Materials Innovation, Washington University, St. Louis, Missouri, USA

D. Meltzer

Department of Anthropology, Southern Methodist University, Dallas, Texas, USA

N. Pinter

Department of Geology, Southern Illinois University, Carbondale, Illinois, USA

A. C. Scott

Department of Earth Sciences, Royal Holloway University of London, Egham, UK

T. Surovell

Department of Anthropology, University of Wyoming, Laramie, Wyoming, USA

P. Claeys

Earth System Science, Vrije Universiteit Brussel, Brussels, Belgium

J. Gill

Department of Geography, University of Wisconsin-Madison, Madison, Wisconsin, USA

F. Paquay

Department of Geology and Geophysics, University of Hawai‘i at Mānoa, Honolulu, Hawaii, USA

J. Marlon

Department of Geography, University of Wisconsin-Madison, Madison, Wisconsin, USA

P. Bartlein

Department of Geography, University of Oregon, Eugene, Oregon, USA

C. Whitlock

Department of Earth Sciences, Montana State University, Bozeman, Montana, USA

D. Grayson

Department of Anthropology, University of Washington, Seattle, Washington, USA

A. J. T. Jull

AMS Radiocarbon Facility, University of Arizona, Tucson, Arizona, USA

We present arguments and evidence against the hypothesis that a large impact or airburst caused a significant abrupt climate change, extinction event, and termination of the Clovis culture at 12.9 ka. It should be noted that there is not one single Younger Dryas (YD) impact hypothesis but several that conflict with one another regarding many significant details. Fragmentation and explosion mechanisms proposed for some of the versions do not conserve energy or momentum, no physics-based model has been presented to support the various concepts, and existing physical models contradict them. In addition, the a priori odds of the impact of a >4 km comet in the prescribed configuration on the Laurentide Ice Sheet during the specified time period are infinitesimal, about one in 1015. There are three broad classes of counterarguments. First, evidence for an impact is lacking. No impact craters of the appropriate size and age are known, and no unambiguously shocked material or other features diagnostic of impact have been found in YD sediments. Second, the climatological, paleontological, and archeological events that the YD impact proponents are attempting to explain are not unique, are arguably misinterpreted by the proponents, have large chronological uncertainties, are not necessarily coupled, and do not require an impact. Third, we believe that proponents have misinterpreted some of the evidence used to argue for an impact, and several independent researchers have been unable to reproduce reported results. This is compounded by the observation of contamination in a purported YD sample with modern carbon.

Citation: Boslough, M., et al. (2012), Arguments and evidence against a Younger Dryas impact event, in Climates, Landscapes, and Civilizations, Geophys. Monogr. Ser., vol. 198, edited by L. Giosan et al. 13–26, AGU, Washington, D. C., doi:10.1029/2012GM001209.


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