Latest Black Sea study says "no flood"
- From: Jack Linthicum <jacklinthicum@xxxxxxxxxxxxx>
- Date: Mon, 23 Feb 2009 03:34:25 -0800 (PST)
"Ryan remains skeptical about the new paper, which he said depended
largely on analyses of just two mollusk shells that were completely
destroyed by the work, leaving no opportunity for the results to be
replicated. Giosan said he has invited Ryan to join him in an effort
to replicate and extend the results by drilling more cores in the
Danube delta."
Ancient Black Sea Flood: Nuisance or Calamity?
Emily Sohn, Discovery News
Feb. 19, 2009 -- Something happened along the shores of the Black Sea
about 9,500 years ago. According to one theory, a huge flood suddenly
drowned the landscape, forcing some of the planet's first farmers to
move elsewhere.
A new study paints a different picture.
"I would say there was never a big flood," said Liviu Giosan, a
geologist at Woods Hole Oceanographic Institute in Cape Cod, Mass.,
and lead author of the study. "What we showed was that it's
impossible."
The new work fuels an ongoing debate about the geologic history of the
Black Sea. Research there has lagged behind other parts of the world,
and many questions remain about how water levels have fluctuated over
the years.
It's a unique place. The Black Sea is an inland sea, surrounded by
Turkey, Georgia, Russia, Ukraine, Romania and Bulgaria. It was once a
freshwater lake surrounded by rich and fertile plains. But about 9,500
years ago, sea levels rose as the climate warmed, and saltwater poured
in from the Mediterranean through the Sea of Marmara.
The fossil record clearly shows a shift from freshwater to saltwater
species around that time. Whether the change happened gradually or
dramatically, however, is something scientists are still debating.
The details are murky because for decades, the Soviets carefully
controlled who did what in the region, said Giosan, himself a native
of Romania. Soviet-funded studies were published over the years, but
the papers were short on details about study methods, making their
conclusions unreliable.
In the mid-1990s, Columbia University geologist William Ryan teamed up
with Russian and Turkish researchers to study the geology of the Black
Sea for the first time with state-of-the-art methods. Based on seven
key observations about the shorelines and fossil record, the team
concluded that there had been a massive, catastrophic flood, which
they dubbed "Noah's Flood." The theory has been controversial ever
since.
Giosan and colleagues approached the question in a new way. Instead of
looking underwater, like previous studies have done, they drilled a 42-
meter (140-foot) hole in the Danube delta -- a flat plain that has
formed out of sediments deposited by the Danube River as it pours into
the Black Sea. Layer by layer, their core samples went back more than
10,000 years -- allowing the scientists to see what happened both
before and after the flood.
By dating sediment layers as well as clam shells that were still
closed shut (indicating that the animals were buried and preserved in
the same place they lived), Giosan's group determined that the Black
Sea was 30 meters (98 feet) below present its level at the time of the
flood, not 80 meters (262 feet) as Ryan's team maintains. That
suggests the flood was much smaller than originally thought.
"It moves the balance of evidence from this being a big, catastrophic
event to its not being such a big event," said oceanographer Mark
Siddall, of the University of Bristol in the United Kingdom.
Ryan remains skeptical about the new paper, which he said depended
largely on analyses of just two mollusk shells that were completely
destroyed by the work, leaving no opportunity for the results to be
replicated. Giosan said he has invited Ryan to join him in an effort
to replicate and extend the results by drilling more cores in the
Danube delta.
Now that the area is open for business, scientists hope that gaining a
clearer picture of the Black Sea's past will help them get to the
bottom of another important question: How much has climate change
contributed to the region's history, and what does the future hold in
store?
http://dsc.discovery.com/news/2009/02/19/black-sea-flood-print.html
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