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The researchers were divided into two teams, each working 14 hours a day, he said. Two of those hours involved just getting to the barge from the shore and getting back.
The drilling, conducted this year, went on for 24 hours a day, although work was limited to the autumn and early spring because of winter storms and fierce summer heat, Ito said.
The core samples were collected in nine-foot plastic pipes about five inches in diameter and sent to Potsdam, Germany, for analysis. The core samples, when analyzed, go back 200,000 years, the Mideast’s longest archive.
The researchers drilled two cores. One, in the middle of the sea, in waters 974 feet deep, recovered samples 1,509 feet below the sea bed. A second core was drilled in several feet of water, down to 1,148 feet below the sea bed, Ben-Avraham said.
About 750 feet down, they found pebbles. Below that was about 120 feet of salt.
The pebbles were clean, uniform and well-rounded. The easiest and most likely explanation is that the pebbles were part of a beach left over when the water disappeared, and the salt below came from the water that used to be there, researchers said. They date the latter condition to about 125,000 years ago.
The samples also record earthquakes, although the quakes have yet to be precisely dated. The area is an active seismic zone, and quakes have been recorded throughout history, including by the historian Josephus during the Roman Empire.
“There have been clusters of earthquakes in history,” Ben-Avraham said. “There is usually a period of quiet followed by clusters of earthquakes. This is worrisome because the 20th century was a quiet period.”
The samples also could resolve a long-standing dispute among archaeologists and between archaeologists and Bible scholars: Did the biblical Israelite leader Joshua really destroy the walls of Jericho with the help of an earthquake some 1,200 years ago, when the Israelites are thought to have crossed the Jordan? The cores should show when quakes occurred. Of course, this would still leave another dispute unresolved. Jericho, just north of the sea, is believed to be the oldest still-inhabited city in the world. But many archaeologists dispute whether there was a walled, inhabited city there at the time in question.
Another byproduct of the research could be insight into the mass human migration out of Africa. When early humans spread into Europe and Asia, they probably passed right through the area, which is pretty much the only way north by land into Eurasia. Because of the nature of the samples, the scientists can even track the climate season by season — wet or dry —– through the years.
Environmental change was the cause of the historic depletion of the sea. The area was warmer and more arid than it is today. Because there were no homo sapiens in the area, what happened back then was due entirely to natural causes.
Ito said scientists, particularly Israeli scientists, believe that, for reasons involving the chemical reaction of water molecules with salt, the Dead Sea could shrink considerably, reaching a point when evaporation stopped, but never actually run dry. Ben-Avraham said a total drying would not happen “in the foreseeable future.“
The drilling research shows that prediction may be wrong, according to Ito. If it happened before, it could happen again.
Contact Joel Shurkin at firstname.lastname@example.org