Dead Sea

The Dead Sea (Arabic البحر الميت, Hebrew ים המלח) is the lowest exposed point on the Earth's surface. It is on the border between the West Bank, Israel, and Jordan on the Jordan Rift Valley. This endorheic body of water is the deepest hypersaline lake in the world.

The Dead Sea is 67 km long, up to 18 km wide and 799 m below sea level in depth at its deepest point. While the surface elevation of the Dead Sea continues to fluctuate, the Dead Sea valley contains the lowest land point on the face of the earth: an elevation of 394 m (1291 ft) below sea level.

The Dead Sea has attracted interest and visitors from around the Mediterranean basin for thousands of years. It was a place of refuge for King David, it was one of the world's first health resorts for Herod the Great, and it has been the supplier of products as diverse as balms for Egyptian mummification to potash for fertilizers.

In Hebrew the Dead Sea is called the  - meaning "sea of salt", or Yam ha-Mavet - meaning "sea of death". In past times it was the "Eastern Sea" or the "Sea of Arava". In Arabic the Dead Sea is called meaning "the Dead Sea", or less commonly Bahr Lūţ meaning "the Sea of Lot". Historically, another Arabic name was the "Sea of Zoar", after a nearby town. To the Greeks, the Dead Sea was "Lake Asphaltites" (see below).The Dead Sea actualy has water flowing into it. The Jordan River runs into the Dead Sea.

Natural history
The Dead Sea is located in the Dead Sea Rift, that is part of a long fissure in the Earth's surface called the Great Rift Valley. The 6000 km (3700 mile) long Great Rift Valley extends from the Taurus Mountains of Turkey to the Zambezi Valley in southern Africa. The Great Rift Valley formed in Miocene times as a result of the Arabian Plate moving northward and then eastward away from the African Plate.

Around three million years ago what is now the valley of the Jordan River, Dead Sea, and Wadi Arabah/Nahal Arava was repeatedly inundated by waters from the Mediterranean Sea. The waters formed in a narrow, crooked bay which was connected to the sea through what is now the Jezreel Valley. The floods of the valley came and went depending on long scale climatic change. The lake that occupied the Dead Sea Rift, named "Lake Sodom", deposited beds of salt, eventually coming to be 3 km (2 miles) thick.

According to geological theory, approximately two million years ago the land between the Rift Valley and the Mediterranean Sea rose to such an extent that the ocean could no longer flood the area. Thus, the long bay became a long lake.

The first such prehistoric lake is named "Lake Gomorrah". Lake Gomorrah was a freshwater or brackish lake that extended at least 80 km (50 miles) south of the current southern end of the Dead Sea and 100 km (60 miles) north, well above the present Hula Depression. As the climate turned more arid, Lake Samra shrank and became saltier. The large, saltwater predecessor of the Dead Sea is called "Lake Lisan".

In prehistoric times great amounts of sediment collected on the floor of Lake Gomorra. The sediment was heavier than the salt deposits and squeezed the salt deposits upwards into what are now the Lisan Peninsula and Mount Sedom (on the southwest side of the lake). "Geologists explain the effect in terms of a bucket of mud into which a large flat stone is placed, forcing the mud to creep up the sides of the pail". When the floor of the Dead Sea dropped further due to tectonic forces the salt mounts of Lisan and Mount Sedom stayed in place as high cliffs. (see salt domes)

The period 23,000 years ago to 18,000 years ago was very dry and the surface level of Lake Lisan fell to a point well below the Dead Sea's surface level today. At the sea's minimum, its waters may have been over 600 m (2,100 feet) below sea level.

Around 12,000 years ago this tiny puddle of the Lake Lisan minimum began to steadily grow again. Around a few thousand years ago, the Dead Sea was about as large as its northern basin is today. There was no southern basin until the late Middle Ages.

The Jordan River is the only major stream flowing into Dead Sea. There are no outlet streams.

The northern part of the Dead Sea receives scarcely 100 mm (4 inches) of rain a year. The southern section barely 50 mm (2 inches). The Dead Sea zone's aridity is due to the rainshadow effect of the Judean Hills. The highlands east of the Dead Sea receive more rainfall than the Dead Sea itself.

The mountains of the western side, the Judean Hills, rise less steeply from the Dead Sea than do the mountains of the eastern side. The mountains of the eastern side are also much higher. Along the southwestern side of the lake is a 210 m (700 ft) tall halite formation called "Mount Sedom".

Chemistry and health effects
Until the winter of 1978-1979, the Dead Sea was composed of two stratified layers of water that differed in temperature, density, age, and salinity. The topmost 35 m or so of the Dead Sea had a salinity that ranged between 300 and 400 parts per thousand and a temperature that swung between 19 °C (66 °F) and 37 °C (98 °F). Underneath a zone of transition, the lowest level of the Dead Sea had waters of a consistent 22 °C (72 °F) temperature and complete saturation of sodium chloride (NaCl). Since the water near the bottom is saturated, the salt precipitates out of solution onto the sea floor.

Beginning in the 1960s water inflow to the Dead Sea from the Jordan River was reduced as a result of large-scale irrigation and generally low rainfall. By 1975 the upper water layer of the Dead Sea was actually saltier than the lower layer. The upper layer nevertheless remained suspended above the lower layer because its waters were warmer and thus less dense. When the upper layer finally cooled down so that its density was greater than the lower layer the waters of the Dead Sea, after many centuries, finally mixed and the lake was a homogeneous body of water. Since then, the stratification has begun to redevelop.

The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53% magnesium chloride, 37% potassium chloride and 8% sodium chloride (salt) with the remainder comprised of various trace elements.

The concentration of sulfate, SO4-2, ions is very low, and the bromide ion concentration is the highest of all waters on Earth. Chlorides neutralize most of the calcium ions in the Dead Sea and its surroundings. While in other seas sodium chloride is 97% of the salts, in the Dead Sea the quantity of NaCl is only 12-18 percent. The water temperature varies from 19 °C in February to 31 °C in August.

Comparison between the chemical composition of the Dead Sea to other lakes and oceans show that the salt concentration in the Dead Sea is 31.5% (the salinity fluctuates somewhat). Because of its unusually high concentration of salt, anyone can easily float in the Dead Sea because of natural buoyancy as a result of the higher density of the water. In this the Dead Sea is similar to the Great Salt Lake in Utah, in the United States.

The water of the Dead Sea has a greasy feel to it. The water stings cuts, and causes pain if it comes in contact with the eyes.

One of the most unusual properties of the Dead Sea is its discharge of asphalt. From deep seeps, the Dead Sea constantly spits up small pebbles of the black substance. After earthquakes, chunks as large as houses may be produced.

The Dead Sea area has become a major center for health research and treatment for several reasons. The mineral content of the waters, the very low content of pollens and other allergens in the atmosphere, the reduced ultraviolet component of solar radiation, and the higher atmospheric pressure at this great depth each have specific health effects. For example: persons suffering reduced respiratory function from diseases such as cystic fibrosis, seem to benefit from the increased atmospheric pressure.

Flora and fauna
The sea is called "dead" because its high salinity means no fish or macroscopic aquatic organisms can live in it, though minuscule quantities of bacteria and microbial fungi are present.

In times of flood the salt content of the Dead Sea can drop from its usual 35% salinity to 30% or lower. In the wakes of rainy winters the Dead Sea temporarily comes to life. In 1980, after one such rainy winter, the normally dark blue Dead Sea turned red. Researchers from Hebrew University found the Dead Sea to be teeming with a type of algae called Dunaliella. The Dunaliella in turn nourished carotenoid-containing (red-pigmented) halobacteria whose presence is responsible for the color change. Since 1980 the Dead Sea basin has been dry and the algae and the bacteria have not returned in measurable numbers.

Many animal species make their homes in the mountains surrounding the Dead Sea. A hiker can see camels, ibexes, hares, hyraxes, jackals, foxes, and even leopards. Hundreds of bird species inhabit the zone as well. Both Jordan and Israel have established nature reserves around the Dead Sea.

The delta of the Jordan river was formerly a veritable jungle of papyrus and palm trees. Flavius Josephus described Jericho as "the most fertile spot in Judea". In Roman and Byzantine times sugarcane, henna, and sycamore all made the lower Jordan valley quite wealthy. One of the most valuable products produced by Jericho was the sap of the balsam tree, which could be made into perfume.

By the nineteenth century Jericho's fertility was a thing of the past.

Human history
The human history of the Dead Sea goes all the way back to remote antiquity. Just north of the Dead Sea is Jericho, the oldest continually occupied town in the world. Somewhere, perhaps on the Dead Sea's southeast shore, are the cities mentioned in the Book of Genesis which were destroyed in the times of Abraham: Sodom and Gomorra and the three other "Cities of the Plain". King David hid from Saul at Ein Gedi nearby.

The Greeks knew the Dead Sea as "Lake Asphaltites", due to the naturally surfacing asphalt. Aristotle wrote about the remarkable waters. During the Egyptian conquest it is said that Queen Cleopatra obtained exclusive rights to build cosmetic and pharmaceutical factories in the area. Later, the Nabateans discovered the value of bitumen extracted from the Dead Sea needed by the Egyptians for embalming their mummies.

Herod the Great, Jesus, and John the Baptist were closely linked with the Dead Sea and its surroundings. In Roman times the Essenes settled in Qumran on the Dead Sea's northern shore. There, in the soft marl of the Dead Sea area, they carved out storage caves for their library. Two thousand years later their library was found and given the name "the Dead Sea Scrolls".

King Herod built several palaces on the Western Bank of the Dead Sea. The most famous was Masada, where, in 66-70 AD, a small group of rebellious Jewish zealots held out against the might of the Roman Legion.

The remoteness of the region attracted Greek Orthodox monks since the Byzantine era. Their monasteries such as Saint George in Wadi Kelt and Mar Saba in the Judean Desert are places of pilgrimage. Bedouin tribes have continuously lived in the area and more recently explorers and scientists arrived to analyze the minerals and conduct research into the unique climate. Since the 1960s, tourists from all the over world have also explored the Dead Sea region.

Potash and Salt Works


In the early part of the 20th century, the Dead Sea began to attract interest from chemists who deduced that the Sea was a natural deposit of potash and bromine. The Palestine Potash Company was chartered in 1929 (after its founder, Moses Novomeysky, a Jewish engineer from Siberia, worked for the charter for over ten years). The first plant was on the north shore of the Dead Sea at Kalia and produced potash, or potassium chloride, by solar evaporation of the brine. Employing Arabs and Jews, it was an island of peace in turbulent times. The company quickly grew into the largest industrial site in the Middle East and in 1934 built a second plant on the southwest shore, in the Sodom area, south of the 'Lashon' region of the Dead Sea. The Dead Sea Works Ltd. was established in 1952 as a state-owned company to extract potash and other minerals from the Dead Sea.

From the Dead Sea brine, Israel produces (2001) 1.77 million tons potash, 206,000 tons elemental bromine, 44,900 tons caustic soda, 25,000 tons magnesium metal, and sodium chloride. On the Jordanian side of the Dead Sea, the Arab Potash Co. (APC), formed in 1956, produces 2.0 million tons of potash annually, as well as sodium chloride and bromine. Both companies use extensive salt evaporation pans that have essentially diked the entire southern end of the Dead Sea for the purpose of producing carnallite, potassium magnesium chloride, which is then processed further to produce potassium chloride. The power plant on the Israeli side allows production of magnesium metal (by a subsidiary, Dead Sea Magnesium Ltd.). The salt evaporation pans are visible from space.

Saving the Dead Sea
As mentioned above, the Dead Sea is rapidly shrinking. Although the Dead Sea would never entirely disappear (because evaporation slows down as surface area decreases and saltiness increases), the Dead Sea as we know it could become a thing of the past.

Because it is not realistic to cease using the Jordan River for human needs, one idea to save the Dead Sea is to bring in water from the Mediterranean or Red Sea, either through tunnels or canals. Although a Mediterranean structure would be shorter, Israel is now committed to building a Red Sea canal in deference to Jordan's needs. The plan is to pump water 400 ft (120 m) up the Arava/Arabah from Aqaba or Eilat, tunnel under the highest point of the Arava/Arabah valley, and then canalize the river of seawater as it falls 1700 ft (520 m) to the Dead Sea. The desalination plant would be constructed in Jordan. On May 9th, 2005, Jordan, Israel, and the Palestinian Authority signed an agreement to begin feasibility studies on the project&mdash;to be officially known as the "Two Seas Canal". The scheme calls for the production of 870 million cubic meters of fresh water per year and 550 megawatts of electricity. The World Bank is supportive of the project.

Other extremely deep points on the earth's surface
The deepest point on the earth's crust is the Mariana Trench, a submarine trench in the western Pacific Ocean. There are ice-covered depressions on the continent of Antarctica that are deeper than the Dead Sea (for example, the Bentley Subglacial Trench).