Emeritus professor of earth science James Kennett and a team of researchers have uncovered new evidence supporting the theory of cosmic impact.
This theory maintains that 12,800 years ago, cosmic impact led to the extinction of all animals living in the last ice age. Kennett and over two dozen colleagues from various institutions analyzed spherules, which are spherical particles ranging from 30 to 150 microns in diameter that are distributed throughout North America, northern South America, western Europe and northern Syria, in what is termed the ‘Younger Dryas’ boundary layer. The study was recently published in the Proceedings of the National Academy of the Sciences, which is the official scientific journal for the academy.
According to Kennett, research has been underway for about five to six years and the study is still ongoing. However, he said findings that have been gathered thus far seem to be indicating more and more that the theory of cosmic impact is valid.
“It’s a controversial topic,” Kennett said. “But the evidence has been increasing quite dramatically in favor of this theory that there was indeed a major cosmic impact with Earth at 12.8 thousand years ago.”
The theory’s hypothesis is that a comet struck the earth, releasing enormous amounts of energy that melted surface sediments and allowed spherules to form in the atmosphere, distributing themselves before settling in the YDB layer. By taking vertical stratographic samples, Kennett said researchers have found a peak abundance of spherules in this particular layer.
James Weaver, senior research scientist at the Wyss Institute at Harvard University, was taught by Kennett during his undergraduate years and he collaborated with Kennett on the research for his graduate years.
Surface and x-ray microanalysis was conducted using electron microscopy and energy dispersive spectroscopy, respectively, and Weaver worked on material characterization of the spherules.
According to Weaver, the geochemistry of the spherules indicated they could not have been formed through any mechanism other than cosmic impact.
“By looking at the elemental morphology and composition, we were able to conclude that these materials were formed by a cosmic impact event,” Weaver said.
Kennett said the volume of the spherules collected, which amounted up to 10 million tons, suggests the great magnitude of the impact.
“An awful lot of this material was produced,” Kennett said. “It was not a small meteorite that hit Earth. It was a major event.”
Kennett said his team has been exploring the relationship between this event and abrupt climactic change, which includes extensive burning of wild grasses and, to an even greater effect, the extinction of many ice age animals.
The research team plans to examine the time of the disappearance of these creatures — including species such as the mammoth, mastodon, North American horse and camels, giant ground sloth, saber-toothed cats and short-faced bear.
“They became extinct very close to the time of the cosmic impact,” Kennett said. “It is reasonable to suggest the cosmic impact caused the extinction of these animals.”
A version of this article appeared on page 1 of May 28, 2013′s print edition of The Daily Nexus.