Microscopic images of grains of melted quartz from the YDB cosmic impact layer at Abu Hureyra, Syria, showing evidence of burst bubbles and flow textures that resulted from the melting and boiling of rock at very high temperatures. (Light microscope image at left; SEM image at right.)
18-member international team of researchers that includes James
Kennett, professor of earth science at UC Santa Barbara, has discovered
melt-glass material in a thin layer of sedimentary rock in Pennsylvania,
South Carolina, and Syria. According to the researchers, the
material—which dates back nearly 13,000 years—was formed at temperatures
of 1,700 to 2,200 C (3,100 to 3,600 F), and is the result of a cosmic
body impacting Earth.
new data are the latest to strongly support the controversial Younger
Dryas Boundary (YDB) hypothesis, which proposes that a cosmic impact
occurred 12,900 years ago at the onset of an unusual cold climatic
period called the Younger Dryas. This episode occurred at or close to
the time of major extinction of the North American megafauna, including
mammoths and giant ground sloths; and the disappearance of the
prehistoric and widely distributed Clovis culture. The researchers’
findings appear this week in the Proceedings of the National Academy of
scientists have identified three contemporaneous levels more than
12,000 years ago, on two continents yielding siliceous scoria-like
objects (SLO’s),” said H. Richard Lane, program director of National
Science Foundation’s Division of Earth Sciences, which funded the
research. “SLO’s are indicative of high-energy cosmic airbursts/impacts,
bolstering the contention that these events induced the beginning of
the Younger Dryas. That time was a major departure in biotic, human and
and geochemical evidence of the melt-glass confirms that the material
is not cosmic, volcanic, or of human-made origin. “The very high
temperature melt-glass appears identical to that produced in known
cosmic impact events such as Meteor Crater in Arizona, and the
Australasian tektite field,” said Kennett.
melt material also matches melt-glass produced by the Trinity nuclear
airburst of 1945 in Socorro, New Mexico,” he continued. “The extreme
temperatures required are equal to those of an atomic bomb blast, high
enough to make sand melt and boil.”
material evidence supporting the YDB cosmic impact hypothesis spans
three continents, and covers nearly one-third of the planet, from
California to Western Europe, and into the Middle East. The discovery
extends the range of evidence into Germany and Syria, the easternmost
site yet identified in the northern hemisphere. The researchers have yet
to identify a limit to the debris field of the impact.
Photos of melt glass known as trinitite formed at the ground surface from the melting of sediments and rocks by the very high temperatures of the Trinity nuclear airburst in New Mexico in 1945. This material is very similar to the glassy melt materials now reported from the cosmic impact YDB layer, consistent with the very high temperature origin of the melt materials in the YDB layer.
these three sites in North America and the Middle East are separated by
1,000 to 10,000 km, there were most likely three or more major
impact/airburst epicenters for the YDB impact event, likely caused by a
swarm of cosmic objects that were fragments of either a meteorite or
comet,” said Kennett.
PNAS paper also presents examples of recent independent research that
supports the YDB cosmic impact hypothesis, and supports two independent
groups that found melt-glass in the YDB layers in Arizona and Venezuela.
“The results strongly refute the assertion of some critics that ‘no one
can replicate’ the YDB evidence, or that the materials simply fell from
space non-catastrophically,” Kennett noted.
added that the archaeological site in Syria where the melt-glass
material was found—Abu Hureyra, in the Euphrates Valley—is one of the
few sites of its kind that record the transition from nomadic
hunter-gatherers to farmer-hunters who live in permanent villages.
“Archeologists and anthropologists consider this area the ‘birthplace of
agriculture,’ which occurred close to 12,900 years ago,” Kennett said.
presence of a thick charcoal layer in the ancient village in Syria
indicates a major fire associated with the melt-glass and impact
spherules 12,900 years ago,” he continued. “Evidence suggests that the
effects on that settlement and its inhabitants would have been severe.”
scientists contributing to the research include Ted Bunch and James H.
Wittke of Northern Arizona University; Robert E. Hermes of Los Alamos
National Laboratory; Andrew Moore of the Rochester Institute of
Technology; James C. Weaver of Harvard University; Douglas J. Kennett of
Pennsylvania State University; Paul S. DeCarli of SRI International;
James L. Bischoff of the U.S. Geological Survey; Gordon C. Hillman of
the University College London; George A. Howard of Restoration Systems;
David R. Kimbel of Kimstar Research; Gunther Kletetschka of Charles
University in Prague, and of the Czech Academy of Science; Carl Lipo and
Sachiko Sakai of California State University, Long Beach; Zsolt Revay
of the Technical University of Munich in Germany; Allen West of
GeoScience Consulting; and Richard B. Firestone of Lawrence Berkeley