Evidence for an Extraterrestrial Impact 12,900 Years Ago That Contributed to the Megafaunal Extinctions and the Younger Dryas Cooling

Details

• Personal Author:
  Becker L ; Belgya T ; Bunch TE ; Darrah T ; Dickenson OJ ; Erlandson JM ; Firestone RB ; Goodyear AC ; Harris RS ; Howard GA ; Kennett DJ ; Kennett JP ; Kloosterman JB ; Lechler P ; Mayewski PA ; Montgomery J ; Poreda R ; Que Hee SS ; Revay ZS ; Schultz PH ; Smith AR ; Stich A ; Topping W ; West A ; Wittke JH ; Wolbach WS
• Description:
  A carbon-rich black layer, dating to approx. 12.9 ka, has been previously identified at approx. 50 Clovis-age sites across North America and appears contemporaneous with the abrupt onset of Younger Dryas (YD) cooling. The in situ bones of extinct Pleistocene megafauna, along with Clovis tool assemblages, occur below this black layer but not within or above it. Causes for the extinctions, YD cooling, and termination of Clovis culture have long been controversial. In this paper, we provide evidence for an extraterrestrial (ET) impact event at approx. equal to 12.9 ka, which we hypothesize caused abrupt environmental changes that contributed to YD cooling, major ecological reorganization, broad-scale extinctions, and rapid human behavioral shifts at the end of the Clovis Period. Clovis-age sites in North American are overlain by a thin, discrete layer with varying peak abundances of (i) magnetic grains with iridium, (ii) magnetic microspherules, (iii) charcoal, (iv) soot, (v) carbon spherules, (vi) glass-like carbon containing nanodiamonds, and (vii) fullerenes with ET helium, all of which are evidence for an ET impact and associated biomass burning at approx. 12.9 ka. This layer also extends throughout at least 15 Carolina Bays, which are unique, elliptical depressions, oriented to the northwest across the Atlantic Coastal Plain. We propose that one or more large, low-density ET objects exploded over northern North America, partially destabilizing the Laurentide Ice Sheet and triggering YD cooling. The shock wave, thermal pulse, and event-related environmental effects (e.g., extensive biomass burning and food limitations) contributed to end-Pleistocene megafaunal extinctions and adaptive shifts among PaleoAmericans in North America. [Description provided by NIOSH]
• Subjects:
  Geology Occupational Health Safety
• Keywords:
  Author Keywords: Comet Climatic Effects Ecological Systems Environmental Physiology Geologic Formations Iridium Micrometeorites Nanodiamonds Nanomaterials Natural Disasters Spherules

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• ISSN:
  0027-8424
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Arizona ; California ; Illinois ; Maine ; Michigan ; Nevada ; New Mexico ; New York ; North Carolina ; Oregon ; OSHA Region 1 ; OSHA Region 10 ; OSHA Region 2 ; OSHA Region 4 ; OSHA Region 5 ; OSHA Region 6 ; OSHA Region 9 ; Rhode Island ; South Carolina
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  104
• Issue:
  41
• NIOSHTIC Number:
  nn:20058363
• Citation:
  Proc Natl Acad Sci U.S.A. 2007 Oct; 104(41):16016-16021
• Contact Point Address:
  R. B. Firestone, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
• Email:
  rbfirestone@lbl.gov
• Federal Fiscal Year:
  2008
• Performing Organization:
  University of California Los Angeles
• Peer Reviewed:
  True
• Start Date:
  20050701
• Source Full Name:
  Proceedings of the National Academy of Sciences of the United States of America
• End Date:
  20270630
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:28517cd47fde832afbed18fd58c22ff63a8774347a1a010f4d2d5037688fb2586755ec7557e56757c63b7e378366220c1b1b941e3fbd5663a21a68603096873f
• Download URL:
  https://stacks.cdc.gov/view/cdc/221478/cdc_221478_DS1.pdf
• File Type:
  [PDF - 795.72 KB ]