The dead sea dried up in the past

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SAN FRANCISCO, CALIFORNIA—The Dead Sea region has been a center of human activity for hundreds of thousands of years—and the layers of sediments buried beneath the lake, scientists think, hold clues to the changing environment in which those cultures existed. Now, an analysis of sediments drawn from the center of the lake basin reported here this week at the American Geophysical Union's annual meeting reveals that, contrary to what scientists previously believed, the lake once completely dried up.

The study is part of the Dead Sea Deep Drilling Project, a $2.6 million effort begun 10 years ago to recover the longest, most continuous, and best-preserved archive of environmental and seismic information in the Middle East. Following two drilling efforts, one lasting from November 2010 to January 2011, and one in March 2011, project researchers have now extracted a 1-kilometer-long core of sediment from the center of the basin, representing roughly 200,000 years of climate and seismic data for the region. The biggest surprise so far? About 120,000 years ago, the Dead Sea essentially dried up.

Scientists didn't think that would happen. At 425 meters below sea level, the Dead Sea is at the lowest continental elevation on Earth, and it is about 34% saline. That extreme saltiness, scientists thought, would ultimately prevent the lake water from completely evaporating. They were convinced that the lowest the water level in the Dead Sea could sink was about 150 meters below its current level.
 
Well, considering that the Mediterranean Sea dried up completely several million years ago, I don't see why it would be so difficult for the Dead Sea to become totally dessicated also, given the right conditions.
 
Xylene said:
Well, considering that the Mediterranean Sea dried up completely several million years ago, I don't see why it would be so difficult for the Dead Sea to become totally dessicated also, given the right conditions.
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What evidence is there for this? Where was all the sea water?
 
Robittybob1 said:
What evidence is there for this? Where was all the sea water?
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The bottom of the Mediterranean Sea contains extremely high concentrations of salt and gypsum. The Strait of Gibraltar is a very narrow opening in a ridge of solid rock. It's quite probable that it was closed off at one point, sealing the Mediterranean off from the rest of the ocean. Even today, water only flows one way through the Strait, as the Mediterranean loses more to evaporation than it gains from river inflow.
wikipedia.org/wiki/Messinian_salinity_crisis#Evidence
 
arauca said:
That extreme saltiness, scientists thought, would ultimately prevent the lake water from completely evaporating. They were convinced that the lowest the water level in the Dead Sea could sink was about 150 meters below its current level.
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So they thought wrong.

Do you want to talk about climate change during this era, or the vapor pressure of salt water.. is there anything in particular that interests you about this story?
 
Robittybob1 said:
What evidence is there for this?
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Do they not have Wikipedia in your country? The Mediterranean is a very young sea, having formed only about five million years ago.
Where was all the sea water?
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It flowed in from the Atlantic when the Straits of Gibraltar opened up.

The Mediterranean has an average depth of only 1500m and it's not very wide. So if the Straits were closed off again and all the water were scooped out of it and dumped back into the ocean where it came from, it would not raise sea level by more than a couple of meters. (Feel free to double-check my arithmetic, I only estimated the total surface area of the earth's oceans.)

BTW: The Mediterranean did not "dry up." This is the first time it's ever contained water.
 
Aqueous Id said:
So they thought wrong.

Do you want to talk about climate change during this era, or the vapor pressure of salt water.. is there anything in particular that interests you about this story?
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My point was to establish a date . relating to some migration from Ethiopia
 
Fraggle Rocker said:
So if the Straits were closed off again and all the water were scooped out of it and dumped back into the ocean where it came from, it would not raise sea level by more than a couple of meters. (Feel free to double-check my arithmetic, I only estimated the total surface area of the earth's oceans.)
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According to my calculations it's about 10 meters.
Taking into account land flooding and curvature of the Earth hardly makes a dent in the rise, by the way.
 
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Fraggle Rocker said:
BTW: The Mediterranean did not "dry up." This is the first time it's ever contained water.
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Not entirely, it's a little more complex then that.

The 'Mediterranean' has, for the most part, been open in some form or another since the Triassic (or so - at least, according to the mainstream interpretation.

For example, here is a reconstruction of the Region during the Rupellian (33.9 - 28.4 MYA).

Basically, during the Triassic (map) the Mediterranean was open to the west, rather than the east, but as Africa continued its motion, that ocean (called the Tethys) was closed, however, as the Atlantic ocean opened, the region was opened to the ocean to the east as well as the west.

By the mid miocene the Mediterranean had been squeezed so that it was long and narrow map, and seperated completely from the para-tethys (which gaves us the Caspian sea). The closing continued, and still continues.

6 million years ago there was a series of basin wide salinity crises, by 5.6 million years ago the basin was finally isolated from the atlantic. Between 5.6 and 5.5 million years ago there was extensive erosion as rivers emptying into the mediterranean carved canyons comparable to the grand canyon, and between 5.5 and 5.3 million years ago, the basin was largely dessicated.

As an example of the kind of canyon we're talking about here, there is strong evidence indicating that Cairo sits on top of an 8,200 foot deep canyon (versus 6825 feet for the grand canyon) that is 6-12 miles wide, and reaches as far inland as the Aswan Dam (808 miles versus 199 miles for the grand canyon), but has subsequently been filled in with a mixture fluvial and marine sediments.

(EG source)

The precise extent of the dessication is uncertain, for example one scenario sees one of the basins dried out completely, and the other basin filled with a hypersaline lake. It's also possible that rather than drying out completely, the mediterranean had a hypersaline body of water in it. I believe that some or all of the evaporite deposits are cyclic in nature.

The barrier at the straights of Gilbatrar broke for a final time 5.3 million years ago resulting in the Zanclean flood, and the available evidence suggests that the basin has not dessicated since that time.
 
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Trippy said:
Perhaps you should reconsider your seemingly adversarial approach, it is seldom conducive to reasoned and reasonable discussion.
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Sorry Trippy, It was just that someone else asked me "if we had Wikipedia in my part of the World". I wasn't trying to be adversarial but rather trying to be funny. Was it taken the wrong way? :)
 
arauca said:
ScienceNOW - Up to the minute news from Scienc


SAN FRANCISCO, CALIFORNIA—The Dead Sea region has been a center of human activity for hundreds of thousands of years—and the layers of sediments buried beneath the lake, scientists think, hold clues to the changing environment in which those cultures existed. Now, an analysis of sediments drawn from the center of the lake basin reported here this week at the American Geophysical Union's annual meeting reveals that, contrary to what scientists previously believed, the lake once completely dried up.

The study is part of the Dead Sea Deep Drilling Project, a $2.6 million effort begun 10 years ago to recover the longest, most continuous, and best-preserved archive of environmental and seismic information in the Middle East. Following two drilling efforts, one lasting from November 2010 to January 2011, and one in March 2011, project researchers have now extracted a 1-kilometer-long core of sediment from the center of the basin, representing roughly 200,000 years of climate and seismic data for the region. The biggest surprise so far? About 120,000 years ago, the Dead Sea essentially dried up.

Scientists didn't think that would happen. At 425 meters below sea level, the Dead Sea is at the lowest continental elevation on Earth, and it is about 34% saline. That extreme saltiness, scientists thought, would ultimately prevent the lake water from completely evaporating. They were convinced that the lowest the water level in the Dead Sea could sink was about 150 meters below its current level.
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It would be useful, perhaps, if in the future you could include a link to a source for such articles. It generally encourages more interesting discussion, and enables people to judge the story by its merits.

Dead Sea Dried Up in Past - Science Now

Another version of the same story that includes slightly different information:
A Dry Dead Sea Before Biblical Times

Synopsis: They did some drilling, and at a depth consistent with 120,000 years ago, they found a layer of pebbles consistent with a beach deposit (specifically, I believe, consistent with moderm dead sea beach deposits) sitting on top of a thick layer of salt consistent with what would be produced should the dead sea dry up.

Conclusion: This new evidence suggests that 120,000 years ago, that the dead sea dried up completely, or came very close to doing so.

Why was this finding surprising?

Because thermodynamics tells us that as the amount of dissolved material in the dead sea increases the amount of energy required to cause more water to evaporate also increases, so it seemed that the Dead Sea simply could not get hot enough to cause it to evaporate entirely?

Isn't this contradicted by the Messinian salinity crisis?

No, not really. The thing to keep in mind about what happened to the Mediterranean is that - considerations of paleoclimate to one side, the Mediterranean is substantially deeper than the Dead Sea. A dry Mediterranean would be a 1500m deep continental depression. This is important to keep in mind, because thermodynamics also tells us that as you move down hill, the air compresses and heats up. This in turn means that a closed off and drying out Mediterranean basin would get substantially hotter than the Dead Sea does, which in turn means that it has the opportunity to do so, where the Dead Sea does not.

Personally, if I were to speculate, I would suggest that there is subtantially more information required before we can judge whether or not the Dead sea dried out 120,000 years ago - more information of Paleotopography, for example, would be good, and more core samples to determine the areal extent of the area that the dead sea was confined to would also be of value (although this might be achieved through seismic surveys).
 
Robittybob1 said:
Sorry Trippy, It was just that someone else asked me "if we had Wikipedia in my part of the World". I wasn't trying to be adversarial but rather trying to be funny. Was it taken the wrong way? :)
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That would be between you and Fraggle, unless he's reported it (which would frankly surprise me).
 
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