Andrew Yee[_1_]
June 7th 07, 06:44 PM
University of California-Santa Barbara
CONTACT
Gail Gallessich, 805-893-7220
FEATURED RESEARCHER
Luann Becker, 206-465-1005
May 23, 2007
Ancient Meteor Blast May Have Caused Extinctions, Report UC Santa Barbara
Scientists
Santa Barbara, Calif. -- New scientific findings suggest that a large,
extraterrestrial rock may have exploded over North America 13,000 years ago,
explaining riddles that scientists have wrestled with for decades, including
an abrupt cooling of the atmosphere and the extinction of large mammals.
Two scientists from the University of California, Santa Barbara presented
the discovery today, along with two other researchers at a news conference
at the annual meeting of the American Geophysical Union being held in
Acapulco, Mexico. Over 20 scientists contributed to the discovery.
James Kennett, paleoceanographer and professor emeritus in the Department of
Earth Science at UC Santa Barbara, said that the discovery potentially
explains three of the most-debated controversies of recent decades.
"This is what happens when you do interdisciplinary science," said Luann
Becker, research scientist with UC Santa Barbara's Institute of Crustal
Studies. "You can solve some of the bigger problems."
The time period in question is called the "Younger Dryas," a time of abrupt
cooling that lasted for about 1,000 years and occurred during an
inter-glacial warm period. Evidence for the temperature change is recorded
in ice cores.
According to the scientists, the extraterrestrial rock must have been about
five kilometers across, and either exploded in the atmosphere or directly
hit the Laurentide ice sheet located in the Northeastern section of North
America. Wildfires across the continent would have resulted from the fiery
impact, killing off the vegetation that was the food supply of many of the
larger mammals like the woolly mammoths, causing them to go extinct. Since
the Clovis people of North America hunted the mammoths as a major source of
their food, they too were affected by the impact and their culture died out,
explained Becker.
The scientific team visited over a dozen archaeological sites in North
America where they found high concentrations of iridium, an element that is
rare on Earth, and is almost exclusively associated with meteors. They found
microspherules of glass-like carbon, which form at high temperatures and are
thought to be a result of the impact blast. Also present were another type
of impact tracer -- carbon molecules called fullerenes with gases trapped
inside.
The team concluded that the impact of the space rock melted a large portion
of the Laurentide ice sheet, causing enormous amounts of cool, fresh water
to flow into the Atlantic and Arctic Oceans. This would have caused a major
disruption of the circulation of warm and cold water in these oceans,
leading to a cooler atmosphere and the glaciation of the Younger Dryas
period.
The scientists found evidence for the impact as far west as the Santa
Barbara Channel Islands. Kennett said that the best examples from the West
Coast were found at a site on Santa Rosa Island.
The Paleoclimate Program of the National Science Foundation and NASA funded
this research.
CONTACT
Gail Gallessich, 805-893-7220
FEATURED RESEARCHER
Luann Becker, 206-465-1005
May 23, 2007
Ancient Meteor Blast May Have Caused Extinctions, Report UC Santa Barbara
Scientists
Santa Barbara, Calif. -- New scientific findings suggest that a large,
extraterrestrial rock may have exploded over North America 13,000 years ago,
explaining riddles that scientists have wrestled with for decades, including
an abrupt cooling of the atmosphere and the extinction of large mammals.
Two scientists from the University of California, Santa Barbara presented
the discovery today, along with two other researchers at a news conference
at the annual meeting of the American Geophysical Union being held in
Acapulco, Mexico. Over 20 scientists contributed to the discovery.
James Kennett, paleoceanographer and professor emeritus in the Department of
Earth Science at UC Santa Barbara, said that the discovery potentially
explains three of the most-debated controversies of recent decades.
"This is what happens when you do interdisciplinary science," said Luann
Becker, research scientist with UC Santa Barbara's Institute of Crustal
Studies. "You can solve some of the bigger problems."
The time period in question is called the "Younger Dryas," a time of abrupt
cooling that lasted for about 1,000 years and occurred during an
inter-glacial warm period. Evidence for the temperature change is recorded
in ice cores.
According to the scientists, the extraterrestrial rock must have been about
five kilometers across, and either exploded in the atmosphere or directly
hit the Laurentide ice sheet located in the Northeastern section of North
America. Wildfires across the continent would have resulted from the fiery
impact, killing off the vegetation that was the food supply of many of the
larger mammals like the woolly mammoths, causing them to go extinct. Since
the Clovis people of North America hunted the mammoths as a major source of
their food, they too were affected by the impact and their culture died out,
explained Becker.
The scientific team visited over a dozen archaeological sites in North
America where they found high concentrations of iridium, an element that is
rare on Earth, and is almost exclusively associated with meteors. They found
microspherules of glass-like carbon, which form at high temperatures and are
thought to be a result of the impact blast. Also present were another type
of impact tracer -- carbon molecules called fullerenes with gases trapped
inside.
The team concluded that the impact of the space rock melted a large portion
of the Laurentide ice sheet, causing enormous amounts of cool, fresh water
to flow into the Atlantic and Arctic Oceans. This would have caused a major
disruption of the circulation of warm and cold water in these oceans,
leading to a cooler atmosphere and the glaciation of the Younger Dryas
period.
The scientists found evidence for the impact as far west as the Santa
Barbara Channel Islands. Kennett said that the best examples from the West
Coast were found at a site on Santa Rosa Island.
The Paleoclimate Program of the National Science Foundation and NASA funded
this research.