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The Younger Dryas extinction occurred at the close of the Younger Dryas cold period (11,700 years ago), that witnessed an existential threat to life in North America. It included the disappearance of mastodons, short-faced bears, giant ground sloths, saber-toothed cats and American camels and horses.[1]

Solar triggeringEdit

Variable Solar irradiance may have played a much more prominent role in forcing Pleistocene climate changes. It is proposed that an abrupt reduction in solar irradiance triggered the start of the Younger Dryas, supported by three observations: (1) the abrupt and strong increase in residual 14C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an ∼2500 year quasi-cycle — also found in the 14C record — that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere.[2]

Impact hypothesisEdit

The Younger Dryas Extinction Impact Related?-0

The Younger Dryas Extinction Impact Related?-0

The findings of 13,000 year old nanodiamonds across three continents, assumes support for a comet impact scenario, at the end of the Pleistocene period.[3] However, geologist Robert M. Schoch points out that, for nanodiamonds to be related to comet impact, they must have a lonsdaleite identification, which none of the current findings show.[4]

ReferencesEdit

  1. Nanodiamonds Are Forever, by Julie Cohen, August 28, 2014
  2. Quaternary International, Volumes 68–71, June 2000, Pages 373-383, Reduced solar activity as a trigger for the start of the Younger Dryas? by Hans Renssen, Bas van Geel, Johannes van der Plicht, Michel Magny
  3. Nanodiamonds Are Forever, by Julie Cohen, August 28, 2014
  4. R. M. Shcoch lecture, Ice Age Civilizations