A new study published in The Journal of Geology provides support for the theory that a cosmic impact climate change known as the Younger Dryas stadial, or “Big Freeze.”
event over North America some 13,000 years ago caused a major period of
Around 12,800 years ago, a sudden, catastrophic event plunged much of
the Earth into a period of cold climatic conditions and drought. This
drastic climate change — the Younger Dryas
— coincided with the extinction of Pleistocene megafauna, such as the
saber-tooth cats and the mastodon, and resulted in major declines in
prehistoric human populations, including the termination of the Clovis culture.
With limited evidence, several rival theories have been proposed
about the event that sparked this period, such as a collapse of the
North American ice sheets, a major volcanic eruption, or a solar flare.
However, in a study published in The Journal of Geology, an
international group of scientists analyzing existing and new evidence
have determined a cosmic impact event, such as a comet or meteorite, to
be the only plausible hypothesis to explain all the unusual occurrences
at the onset of the Younger Dryas period.
Researchers from 21 universities in 6 countries believe the key to
the mystery of the Big Freeze lies in nanodiamonds scattered across
Europe, North America, and portions of South America, in a
50-million-square-kilometer area known as the Younger Dryas Boundary
(YDB) field.
Microscopic nanodiamonds, melt-glass, carbon spherules, and other
high-temperature materials are found in abundance throughout the YDB
field, in a thin layer located only meters from the Earth’s surface.
Because these materials formed at temperatures in excess of 2200 degrees
Celsius, the fact they are present together so near to the surface
suggests they were likely created by a major extraterrestrial impact
event.
In addition to providing support for the cosmic impact event
hypothesis, the study also offers evidence to reject alternate
hypotheses for the formation of the YDB nanodiamonds, such as by
wildfires, volcanism, or meteoric flux.
The team’s findings serve to settle the debate about the presence of
nanodiamonds in the YDB field and challenge existing paradigms across
multiple disciplines, including impact dynamics, archaeology,
paleontology, limnology, and palynology.
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