|Primary sources||Jordan River|
|Catchment area||40,650 km² (25,258 mi²)|
|Max length||67 km (42 mi)|
|Max width||18 km (11 mi)|
|Surface area||810 km² (North Basin)|
|Average depth||120 m (394 ft)|
|Max depth||330 m (1,083 ft)|
|Water volume||147 km³ (91 mi³)|
|Shore length1||135 km (84 mi)|
|Surface elevation||-418 m (-1,371 ft)|
|1 Shore length is an imprecise measure which may not be standardized for this article.|
The Dead Sea (Arabic: البحر الميت, Hebrew: ים המלח, translated as Sea of Salt), is a salt lake lying on the border between the nations of Israel and Jordan. Commonly known as the Earth's lowest point, it occurs at 1,371 feet (418 m) below sea level, making its shores the Earth's lowest point not under water or ice. It is the deepest hypersaline lake in the world, at 1,083 feet (330 m) deep. It is also the second saltiest body of water on Earth, with a salinity of about 30 percent (approximately 8.6 times greater than average ocean salinity). Only Lake Asal in Djibouti has a higher salinity.
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, 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. The area holds significance in Jewish, Muslim and Christian faiths as the location for events important in their historical records.
The Dead Sea is located in the Dead Sea Rift, which is part of a long fissure in the Earth's surface called the Great Rift Valley. The 3,700 mile (6,000 km ) long Great Rift Valley extends from the Taurus Mountains of Turkey to the Zambezi Valley in southern Africa. The Dead Sea lies 1,300 feet (400 metres) below sea level, making it the lowest elevation and the lowest body of water in the world.
The Dead Sea lies between the hills of Judea to the west and the Transjordanian plateaus to the east. Along the southwestern side of the Sea is a 700 foot (210 m) tall halite formation known as "Mount Sedom." Its eastern shore belongs to Jordan, and the southern half of its western shore belongs to Israel. The northern half of the western shore lies within the Palestinian West Bank and has been under Israeli occupation since the 1967 Arab-Israeli war. 
It is completely landlocked, with the Jordan River the only major river flowing into it. The inflow from the Jordan averages 19 billion cubic feet (540 million cubic meters) per year. There are smaller rivers and streams flowing down from the surrounding hills that feed into the Sea as well. There are no outlet streams, meaning that any water leaving the sea must do so through evaporation. When the water evaporates, it leaves behind all its dissolved minerals.
In times of flood the salt content of the Dead Sea can drop from its usual 35 percent salinity to 30 percent 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.
Lying within a desert, rainfall is scanty and irregular. The northern area of the Dead Sea receives scarcely four inches (100 mm) of rain per year, with the southern section receiving barely two 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 area has year–round sunny skies and dry air with low pollution.
The average temperatures are from 32 to 39 degrees Celsius in the summer and between 20 and 23 degrees C in the winter. The region has weakened UV radiation, particularly the UVB (erythrogenic rays), and a high oxygen content due to the high barometric pressure. The shore is the lowest dry place in the world. 
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. Even though the Dead Sea sustains little or no life, the ecosystem surrounding it is teeming with life. The skies are filled with migratory birds travelling between Africa and Europe, while hundreds of species make their home there. Animals such as bats, wild cats, camels, ibex, hares, hyraxes, jackals, foxes, and even leopards find refuge in its surrounding mountains. Both Jordan and Israel have established nature reserves around the Dead Sea. Modern-day communal Kibbutz settlements have sprung up in the area, maintaining close-knit social structures in harmony with nature.
The delta of the Jordan River was formerly a veritable jungle of papyrus and palm trees. In the first century historian Flavius Josephus described Jericho, just north of the Dead Sea, 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.
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 was repeatedly inundated by waters from the Red 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, Lake Sodom, deposited beds of salt, eventually becoming two miles (three km) 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 50 miles (80 km) south of the current southern end of the Dead Sea and 60 miles (100 km) north, well above the present Hula Depression. As the climate turned more arid, Lake Gomorrah 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 Gomorrah. 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.
This level of Lake Lisan fluctuated dramatically, rising to its highest level around 26,000 years ago, indicating a very wet climate in the Near East at that time. Around 10,000 years ago the lake level dropped dramatically, probably to levels even lower than today. During the last several thousand years the lake has fluctuated approximately 400 meters with significant drops and rises.
The human history of the Dead Sea dates 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 time of Abraham: Sodom and Gomorrah and the three other "Cities of the Plain" - Admah, Zeboim and Zoar (Deuteronomy 29:23). 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, which was extracted from the Dead Sea and used by the Egyptians for embalming their dead.
In Roman times, Essenes had settled on the Dead Sea's western shore; Pliny the Elder identifies their location with the words, "on the west side of the Dead Sea, away from the coast … [above] the town of Engeda." Ruins of that 200 B.C.E. town, on the north-western tip of the salty lake, feature excavations, caves and an ancient cemetery. It is a popular hypothesis that the Essene settlement he referred to is related to the settlers at Qumran, the site of the discovery of the Dead Sea Scrolls discovered during the twentieth century.
- King Herod the Great built or re-built several fortresses and palaces on the Western Bank of the Dead Sea. The most famous was Masada, where, in 66-70 C.E., a small group of Jews held out against the might of the Roman Legion. The two-year siege culminated in the mass suicide of the Jewish defenders.
- Machaerus, a fortified hilltop palace located in Jordan on the eastern side of the Dead Sea is understood to be the location of the imprisonment and execution of John the Baptist.
- Kasr el Yahud, on the western bank of the Jordan a few kilometers to the north, is believed by many to be the true baptismal site of Jesus.
In Islamic tradition, the importance of the Dead Sea is its relationship to the Prophet Lut (Lot). Lot is considered to be a prophet and the first person other than Abraham himself to believe in the teaching that came to be known later as Islam. According to the teachings of the Qur'an, Lot was commanded by God to go to the cities of Sodom and Gomorrah to preach against homosexuality. Lut's prophetic message, however, was rejected, and thus Sodom and Gomorrah were destroyed.
Bedouin tribes have continuously lived in the Dead Sea area, and more recently explorers and scientists arrived to analyze the minerals and conduct research into the unique climate. Tourism in the region has been developed since the 1960s.
Chemicals and health
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 meters 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 and 37 °C (66 – 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 mixed. For the first time in centuries the lake was a homogeneous body of water. Since then stratification has begun to redevelop. 
The mineral content of the Dead Sea is significantly different from that of ocean water, consisting of approximately 53 percent magnesium chloride, 37 percent potassium chloride and 8 percent sodium chloride (common salt) with the remainder comprised of various trace elements.
The concentration of sulfate, SO42-, 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 percent of the salts, in the Dead Sea the quantity of NaCl is only 12-18 percent.
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 percent (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 aspect, the Dead Sea is similar to the Great Salt Lake in Utah, in the United States. 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 Earth's 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. 
Sufferers of the skin disorder psoriasis also benefit from the ability to sunbathe for long periods in the area due to its position below sea level and subsequent result that many of the sun's harmful UV rays are reduced. Furthermore, Dead Sea salt has been found to be beneficial to psoriasis patients. 
Scientific research supports several types of therapy in practice at the Dead Sea. Natural elements such as climate, sunshine, water, air, and black mud are the important healing elements used. The unusual combination present provides the capability to rehabilitate and restore physiological functions.
The elements used are proven to be nearly free of side effects, pleasant, safe for children and pregnant women, as well as having proven to be highly effective.
- Climatotherapy:- Treatment which exploits local climatic features such as temperature, humidity, sunshine, Barometric pressure and special Atmospheric constituents.
- Heliotherapy:- Treatment that exploits the biological effects of the sun's radiation.
- Thalassotherapy:- Treatment that exploits bathing in Dead Sea water.
- Balneotherapy:- Treatment that exploits black mineral mud of the Dead Sea. 
Besides the unique water and minerals of the Dead Sea itself, there are also health spas and hot springs along the shores. The Jordanian side sports hotels and resorts equipped with spas. On the Israeli side is a hotel resort with spa, pools and a water park. As the area's fame grows, family vacations coupled with health benefits are becoming possible.
Chemicals and business
In the early part of the twentieth 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 both 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 1.77 million tons potash, 206,000 tons elemental bromine, 44,900 tons caustic soda, 25,000 tons magnesium metal, and sodium chloride (2001 figures). On the Jordanian side, Arab Potash (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.
Recession of the Dead Sea
In recent decades, the Dead Sea has been rapidly shrinking because of diversion of incoming water. From an elevation of 395 m below sea level in 1970  it fell 22 m to 418 m below sea level in 2006, reaching a drop rate of 1 m per year. Although the Dead Sea may never entirely disappear, because evaporation slows down as surface area decreases and salinity increases, it is feared that the Dead Sea may substantially change its characteristics.
The Dead Sea level drop has been followed by a groundwater level drop, causing brines that once occupied underground layers near the shoreline to be flushed out by freshwater. This is believed to be the cause of the recent appearance of large sinkholes along the western shore – incoming freshwater dissolves salt layers, rapidly creating subsurface cavities that subsequently collapse to form these sinkholes. 
One of the plans suggested as a means to stop the recession of the Dead Sea is to channel water from the Mediterranean Sea or the Red Sea, either through tunnels or canals (the proposed Dead Sea Canal). 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 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 520 m to the Dead Sea. The desalination plant would be constructed in Jordan.
On May 9, 2005, Jordan, Israel, and the Palestinian Authority signed an agreement to begin feasibility studies on the project, 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. However, several environmental groups have raised concerns about possible negative impacts of the project on the natural environment of the Dead Sea and Arava.
Related global extremes
- West Antarctica's Don Juan Pond has a greater salinity than the Dead Sea, at 18 times ocean salinity.
- 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 (such as the Bentley Subglacial Trench).
- The world's deepest lake is Lake Baikal in Siberia, Russia.
Sources and Further Reading
- Enzel, Yehouda, Amotz Agnon, and Mordechai Stein. 2006. New frontiers in Dead Sea paleoenvironmental research. Boulder, CO: Geological Society of America. ISBN 0813724015 and ISBN 9780813724010
- Niemi, Tina M., Zvi Ben-Avraham, and Joel Gat. 1997. The Dead Sea: the lake and its setting. Oxford monographs on geology and geophysics, no. 36. New York: Oxford University Press. ISBN 9780195087031
- ↑ International Lake Environment Committee. Dead Sea Data Summary. Retrieved August 24, 2007.
- ↑ Encyclopædia Britannica. 2007. Dead Sea, Encyclopædia Britannica Online. Retrieved August 24, 2007.
- ↑ Extreme Science. Lowest Elevation: Dead Sea Retrieved August 23, 2007.
- ↑ Mandala Projects. Deaad Sea Canal, Retrieved August 24, 2007.
- ↑ The Dead Sea Research Center. Asthma, Cystic Fibrosis, Chronic Obstructive Lung Disease, Retrieved August 24, 2007.
- ↑ S. Halevy et al. "Dead sea bath salt for the treatment of psoriasis vulgaris: a double-blind controlled study." Journal of the European Academy of Dermatology and Venereology, 9(3): 237-242.
- ↑ DAV school magazine IV (March-April 2005)
- ↑ C. Klein, A. Flohn, "Contribution to the Knowledge in the Fluctuations of the Dead Sea Level." Theoretical and Applied Climatology 38 (1987): 151–156.
- ↑ M. Abelson, Y. Yechieli, O. Crouvi, G. Baer, D. Wachs, A. Bein, V. Shtivelman. "Evolution of the Dead Sea Sinkholes," in New Frontiers in Dead Sea Paleoenvironmental Research (Geological Society of America, special paper 401, (2006), 241–253.
- Ezekiel's Water Project. Ezekiel's Water Project. Retrieved May 24, 2007.
- Booth, Robert. September 3, 2006. Race is on to save the Dead Sea. Times Online. Retrieved May 24, 2007.
- Life from the Dead Sea Overview. Wysinfo Docuweb. Retrieved May 24, 2007.
- Integrated Water Resources Management in the Lower Jordan Rift Valley. Smart.Retrieved May 24, 2007.
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