Tuesday, September 21, 2010

Video: How the Red Sea Could Have Parted


accounts of the Red Sea’s parting are hydrologically plausible, suggest computer
simulations of sustained winds in a coastal lagoon where the Nile met the
Mediterranean 3,000 years ago.

Under steady 60-mph winds, “the ocean model produces an area of exposed mud
flats where the river mouth opens into the lake,” wrote National Center for
Atmospheric Research oceanographers Carl Drews and Weiqing Han in an August 30
Public Library of Science One study. “These mud flats represent the
area of crossing, and the crossing party would observe water to their left and

In the Book
of Exodus
, Moses is described as leading Israelite slaves in flight from
Egypt, arriving at the Red Sea’s shores just ahead of pursuing armies. At that
point, “Moses stretched out his hand over the sea; and the Lord caused the sea
to go back by a strong east wind all that night, and made the sea dry land, and
the waters were divided.”

Han and Drews, who hosts a
dedicated to the compatibility of science and Christian faith, don’t
consider the Exodus narrative to be literally true, but rather “an interesting
and ancient story of uncertain origin.” Others have been similarly intrigued,
suggesting that a rare phenomenon called wind setdown could have created dry
passage across the Red Sea’s narrow northern tip. A wind setdown is essentially
the flip side of a storm surge; when strong, steady winds cause water to rise
dramatically in some areas, it necessarily drops in others.

In 1879, theologian Samuel Bartlett proposed a setdown location at a shallow
inlet near of Suez, used by Arabs to cross the Red Sea at low tide. More
recently, Russian researchers Naum Voltzinger and Alexei Androsov calculated
that a 74-mph wind could have exposed an underwater reef near what is now the
Suez Canal.

In the new study, Han and Drews determined that the depressions in the reef
would have stayed underwater. They propose a different
, 75 miles north of the reef and just south of the Mediterranean, in
what is now known as the Kedua Gap. The area is now dry, but historical
reconstructions suggest an ancient branch of the Nile once flowed into a lagoon

After using satellite measurements and archaeological records to create a
model of local hydrogeography, the researchers ran simulations that found 12
hours of 60-mph easterly winds would have exposed a dry passage, 2 miles long
and 3 miles wide, out of Egypt.

When the winds stopped blowing, the waters would surge back, appearing in the
researchers’ words “as an advancing wall of churning water” — or, per Exodus,
“the waters returned, and covered the chariots, and the horsemen, and all the
host of Pharaoh that came into the sea after them; there remained not so much as
one of them.”

“If a crossing actually took place here, any debris field of military
artifacts should be found to the north of the gap,” wrote Han and Drews.

Video: Tim Scheitlin and Ryan McVeigh, NCAR. Image: Nicolas Poussin,
The Crossing of the Red Sea./Wikimedia Commons.

See Also:

Citation: “Dynamics of Wind Setdown at Suez and the Eastern Nile Delta.”
By Carl Drews and Weiqing Han. Public Library of Science One, Vol. 5 No. 8,
Augusts 30, 2010.

Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working
on an ecological tipping point

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