Dead Sea
البحر الميت (Arabic) ים המלח (Hebrew)
A view of the sea from the Jordanian shore with the hills of the West Bank in the background
Dead Sea
Location	Western Asia
Coordinates	31°30′N 35°30′E / 31.500°N 35.500°E / 31.500; 35.500
Lake type	Endorheic Hypersaline
Primary inflows	Jordan River
Primary outflows	None
Catchment area	41,650 km2 (16,080 sq mi)
Basin countries	Jordan, Palestine (Israeli-occupied West Bank), Israel
Max. length	50 km (31 mi)[1] (northern basin only)
Max. width	15 km (9.3 mi)
Surface area	605 km2 (234 sq mi) (2016)[2]
Average depth	188.4 m (618 ft)[3]
Max. depth	298 m (978 ft) (elevation of deepest point, 728 m (2,388 ft) BSL , minus current surface elevation)
Water volume	114 km3 (27 cu mi)[3]
Shore length1	135 km (84 mi)
Surface elevation	−430.5 m (−1,412 ft) (2016)[4]
References	[3][4]
1 Shore length is not a well-defined measure.

The Dead Sea (Arabic: اَلْبَحْر الْمَيِّت, romanized: al-Baḥr al-Mayyit, or اَلْبَحْر الْمَيْت, al-Baḥr al-Mayt; Hebrew: יַם הַמֶּלַח, romanized: Yām hamMelaḥ), also known by other names, is a landlocked salt lake bordered by Jordan to the east and the Israeli-occupied West Bank and Israel to the west.^[5][6] It lies in the Jordan Rift Valley, and its main tributary is the Jordan River.

As of 2019, the lake's surface is 430.5 metres (1,412 ft) below sea level,^[4][7] making its shores the lowest land-based elevation on Earth. It is 304 m (997 ft) deep, the deepest hypersaline lake in the world. With a salinity of 342 g/kg, or 34.2% (in 2011), it is one of the world's saltiest bodies of water^[8] – 9.6 times as salty as the ocean – and has a density of 1.24 kg/litre, which makes swimming similar to floating.^[9][10] This salinity makes for a harsh environment in which plants and animals cannot flourish, hence its name. The Dead Sea's main, northern basin is 50 kilometres (31 mi) long and 15 kilometres (9 mi) wide at its widest point.^[1]

The Dead Sea has attracted visitors from around the Mediterranean Basin for thousands of years. It was one of the world's first health resorts, and it has been the supplier of a wide variety of products, from asphalt for Egyptian mummification to potash for fertilisers. Today, tourists visit the sea on its Israeli, Jordanian and West Bank coastlines.

The Dead Sea is receding at a swift rate; its surface area today is 605 km² (234 sq mi), having been 1,050 km² (410 sq mi) in 1930. Multiple canal and pipeline proposals, such as the scrapped Red Sea–Dead Sea Water Conveyance project,^[11] have been made to reduce its recession.

Names

English

The English name "Dead Sea" is a calque of the Arabic name, itself a calque of earlier Greek and Latin names^{[citation needed]}, in reference to the scarcity of aquatic life caused by the lake's extreme salinity.^[12]

Historical English names include the Salt Sea,^[13] Lake of Sodom^[13] from the biblical account of its destruction^[14] and Lake Asphaltites^[13] from Greek and Latin.

Hebrew

The name "Dead Sea" occasionally appears in Hebrew literature as Yām HamMāvet (ים המוות), 'Sea of Death'.^[12]

The usual biblical^[15] and modern Hebrew name for the lake is the Sea of Salt (ים המלח, Yām HamMelaḥ^ⓘ). Other Hebrew names for the lake also mentioned in the Bible are the Sea of Arabah (ים הערבה, Yām Ha‘Ărāvâ) and the Eastern Sea (הים הקדמוני, HaYām HaQadmōnî).

Arabic

The Arabic name is al-Bahr al-Mayyit^ⓘ (‏البحر الميت‎), or usually without the article al-, so just Bahr etc.^[16]

In Arabic, it is also known as the Sea of Lot (‏بحر لوط‎, Buhayrat,^[17] Bahret, or Birket Lut)^[18] from the nephew of Abraham whose wife was said to have turned into a pillar of salt during the destruction of Sodom and Gomorrah.^[14] Less often, it has been known in Arabic as the Sea of Zo'ar from a formerly important city along its shores.

Ancient Greek and Latin

One ancient name signifies 'Dead Sea' (Greek Νεκρά Θάλασσα, Nekrá Thálassa, Latin (Mare Mortuum).^{[citation needed]}

Because of the large volume of ancient trade in the lake's naturally occurring free-floating bitumen, its usual names in ancient Greek and Roman geography were some form of Asphalt Lake (Greek: Ἀσφαλτίτης or Ἀσφαλτίτις Λίμνη, Asphaltítēs or Asphaltítis Límnē; Latin: Lacus Asphaltites) or Sea (Ἀσφαλτίτης Θάλασσα, Asphaltítēs Thálassa).

Geography

The Dead Sea is an endorheic lake located in the Jordan Rift Valley, a geographic feature formed by the Dead Sea Transform (DST). This left lateral-moving transform fault lies along the tectonic plate boundary between the African Plate and the Arabian Plate. It runs between the East Anatolian Fault zone in Turkey and the northern end of the Red Sea Rift offshore of the southern tip of Sinai. It is here that the Upper Jordan River/Sea of Galilee/Lower Jordan River water system comes to an end.

The Jordan River is the only major water source flowing into the Dead Sea, although there are small perennial springs under and around the Dead Sea, forming pools and quicksand pits along the edges.^[19] There are no outlet streams.

The Mujib River, biblical Arnon, is one of the larger water sources of the Dead Sea other than the Jordan.^[20] The Wadi Mujib valley, 420 m below the sea level in the southern part of the Jordan valley, is a biosphere reserve, with an area of 212 km² (82 sq mi).^[21] Other more substantial sources are Wadi Darajeh (Arabic)/Nahal Dragot (Hebrew), and Nahal Arugot [de] that ends at Ein Gedi.^[20] Wadi Hasa (biblical Zered) is another wadi flowing into the Dead Sea.

Rainfall is scarcely 100 mm (4 in) per year in the northern part of the Dead Sea and barely 50 mm (2 in) in the southern part.^[22] The Dead Sea zone's aridity is due to the rainshadow effect of the Judaean Mountains. The highlands east of the Dead Sea receive more rainfall than the Dead Sea itself.

To the west of the Dead Sea, the Judaean mountains rise less steeply and are much lower than the mountains to the east. Along the southwestern side of the lake is a 210 m (700 ft) tall halite mineral formation called Mount Sodom.

The salt lake bordered by Jordan to the east and Palestine's Israeli-occupied West Bank and Israel to the west. It lies in the Jordan Rift Valley, and its main tributary is the Jordan River.^[5][6]

Geology

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Formation theories

There are two contending hypotheses about the origin of the low elevation of the Dead Sea. The older hypothesis is that the Dead Sea lies in a true rift zone, an extension of the Red Sea Rift, or even of the Great Rift Valley of eastern Africa. A more recent hypothesis is that the Dead Sea basin is a consequence of a "step-over" discontinuity along the Dead Sea Transform, creating an extension of the crust with consequent subsidence.^{[citation needed]}

Sedom Lagoon

During the late Pliocene-early Pleistocene, what is now the valley of the Jordan River, Dead Sea, and the northern Wadi Arabah was repeatedly inundated by waters from the Mediterranean Sea.^[23] The waters formed in a narrow, crooked bay that is called by geologists the Sedom Lagoon, which was connected to the sea through what is now the Jezreel Valley.^{[citation needed]} The floods of the valley came and went depending on long-scale changes in the tectonic and climatic conditions.^[23]

The Sedom Lagoon extended at its maximum from the Sea of Galilee in the north to somewhere around 50 km (30 mi) south of the current southern end of the Dead Sea, and the subsequent lakes never surpassed this expanse. The Hula Depression was never part of any of these water bodies due to its higher elevation and the high threshold of the Korazim block separating it from the Sea of Galilee basin.^[24]

Salt deposits

The Sedom Lagoon deposited evaporites mainly consisting of rock salt, which eventually reached a thickness of 2.3 km (1.43 mi) on the old basin floor in the area of today's Mount Sedom.^[25]

Lake formation

According to Kafri, during the late Neogene, i.e. in the Pliocene (ended c. 2.5 million years ago), the eustatic sea level was at 50-100 metres above the current sea level, thus flooding the northern valleys connecting the Mediterranean Sea with the Jordan Rift Valley, which led to the creation of a crooked-shaped lagoon. This high eustatic sea level situation subsequently came to an end, and the ocean could no longer flood the area. Thus, the long lagoon became a landlocked lake, which - due to the high evaporation rate - retreated toward the lower, southern part of the rift valley.^[24] However, Mordechai Stein considers the formation process as not yet clarified, speaking of a late Pliocene-early Pleistocene process in which tectonics might also have played a part in blocking water ingression from the Mediterranean to its former bay or lagoon.^[23]

The first prehistoric lake to follow the Sedom Lagoon is named Lake Amora (which possibly appeared in the early Pleistocene; its sediments developed into the Amora (Samra) Formation, dated to over 200–80 kyr BP), followed by Lake Lisan (c. 70–14 kyr) and finally by the Dead Sea.^[23]

Lake salinity

The water levels and salinity of the successive lakes (Amora, Lisan, Dead Sea) have either risen or fallen as an effect of the tectonic dropping of the valley bottom, and due to climate variation. As the climate became more arid, Lake Lisan finally shrank and became saltier, leaving the Dead Sea as its last remainder.^[23][24]

From 70,000 to 12,000 years ago, Lake Lisan's level was 100 m (330 ft) to 250 m (820 ft) higher than its current level, possibly due to lower evaporation than in the present.^[26][27] Its level fluctuated dramatically, rising to its highest level around 26,000 years ago, indicating a very wet climate in the Near East.^[28] Around 10,000 years ago, the lake's level dropped dramatically, probably even lower than today. During the last several thousand years, the lake has fluctuated approximately 400 m (1,300 ft), with some significant drops and rises. Current theories as to the cause of this dramatic drop in levels rule out volcanic activity; therefore, it may have been a seismic event.

Salt mounts formation

In prehistoric times,^{[dubious – discuss]} great amounts of sediment collected on the floor of Lake Amora. The sediment was heavier than the salt deposits and squeezed the salt deposits upwards into what are now the Lisan Peninsula and Mount Sodom (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 bucket. When the floor of the Dead Sea dropped further due to tectonic forces, the salt mounts of Lisan and Mount Sodom stayed in place as high cliffs (see salt dome).

Climate

The Dead Sea has a hot desert climate (Köppen climate classification BWh), with year-round sunny skies and dry air. It has less than 50 millimetres (2 in) mean annual rainfall and a summer average temperature between 32 and 39 °C (90 and 102 °F). Winter average temperatures range between 20 and 23 °C (68 and 73 °F). The region has weaker ultraviolet radiation, particularly the UVB (erythrogenic rays). Given the higher atmospheric pressure, the air has a slightly higher oxygen content (3.3% in summer to 4.8% in winter) as compared to oxygen concentration at sea level.^[29][30] Barometric pressures at the Dead Sea were measured between 1061 and 1065 hPa and clinically compared with health effects at higher altitude.^[31] (This barometric measure is about 5% higher than sea level standard atmospheric pressure of 1013.25 hPa, which is the global ocean mean or ATM.) The Dead Sea affects temperatures nearby because of the moderating effect a large body of water has on climate. During the winter, sea temperatures tend to be higher than land temperatures, and vice versa during the summer months. This is the result of the water's mass and specific heat capacity. On average, there are 192 days above 30 °C (86 °F) annually.^[32]

Chemistry

With 34.2% salinity (in 2011), it is one of the world's saltiest bodies of water, though Lake Vanda in Antarctica (35%), Lake Assal in Djibouti (34.8%), Lagoon Garabogazköl in the Caspian Sea (up to 35%) and some hypersaline ponds and lakes of the McMurdo Dry Valleys in Antarctica (such as Don Juan Pond (44%)) have reported higher salinities.

In the 19th century and the early 20th century, the surface layers of the Dead Sea were less salty than today, which resulted in an average density in the range of 1.15-1.17 g/cm³ instead of the present value of around 1.25 g/cm³. A sample tested by Bernays in the 19th century had a salinity of 19%. By the year 1926, the salinity had increased^[34][35] (although it was also suspected that the salinity varies seasonally and depends on the distance from the mouth of the Jordan).

Until the winter of 1978–79, when a major mixing event took place,^[36] the Dead Sea was composed of two stratified layers of water that differed in temperature, density, age, and salinity. The topmost 35 meters (115 ft) or so of the Dead Sea had an average salinity of about 30%, and a temperature that swung between 19 °C (66 °F) and 37 °C (99 °F). Underneath a zone of transition, the lowest level of the Dead Sea had waters of a consistent 22 °C (72 °F) temperature, salinity of over 34%, and complete saturation of sodium chloride (NaCl).^[37] Since the water near the bottom is saturated with NaCl, that 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 was saltier than the lower layer. Nevertheless, the upper layer remained suspended above the lower layer because its waters were warmer and thus less dense. When the upper layer cooled so its density was greater than the lower layer, the waters mixed (1978–79). For the first time in centuries, the lake was a homogeneous body of water. Since then, stratification has begun to redevelop.^[36]

The mineral content of the Dead Sea is very different from that of ocean water. The exact composition of the Dead Sea water varies mainly with season, depth and temperature. In the early 1980s, the concentration of ionic species (in g/kg) of Dead Sea surface water was Cl⁻ (181.4), Br⁻ (4.2), SO₄²⁻ (0.4), HCO₃⁻ (0.2), Ca²⁺ (14.1), Na⁺ (32.5), K⁺ (6.2) and Mg²⁺ (35.2). The total salinity was 276 g/kg.^[38] These results show that the composition of the salt, as anhydrous chlorides on a weight percentage basis, was calcium chloride (CaCl₂) 14.4%, potassium chloride (KCl) 4.4%, magnesium chloride (MgCl₂) 50.8% and sodium chloride (NaCl) 30.4%. In comparison, the salt in the water of most oceans and seas is approximately 85% sodium chloride. The concentration of sulfate ions (SO₄²⁻) is very low, and the concentration of bromide ions (Br⁻) is the highest of all waters on Earth.

The salt concentration of the Dead Sea fluctuates around 31.5%. This is unusually high and results in a nominal density of 1.24 kg/L. Anyone can easily float in the Dead Sea because of natural buoyancy. In this respect the Dead Sea is similar to the Great Salt Lake in Utah in the United States.

An unusual feature of the Dead Sea is its discharge of asphalt. From deep seeps, the Dead Sea constantly spits up small pebbles and blocks of the black substance.^[39] Asphalt-coated figurines and bitumen-coated Neolithic skulls from archaeological sites have been found. Egyptian mummification processes used asphalt imported from the Dead Sea region.^[40][41]

Putative therapies

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The Dead Sea area has become a location for health research and potential treatment for several reasons. The mineral content of the water, the 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 may have specific health effects. For example, persons experiencing reduced respiratory function from diseases such as cystic fibrosis seem to benefit from the increased atmospheric pressure.^[42]

The region's climate and low elevation have made it a popular center for assessment of putative therapies:

• 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

Climatotherapy at the Dead Sea may be a therapy for psoriasis^[43] by sunbathing for long periods in the area due to its position below sea level and subsequent result that UV rays are partially blocked by the increased thickness of the atmosphere^{[citation needed]} over the Dead Sea.^[44]

Rhinosinusitis patients receiving Dead Sea saline nasal irrigation exhibited improved symptom relief compared to standard hypertonic saline spray in one study.^[45]

Dead Sea mud pack therapy has been suggested to temporarily relieve pain in patients with osteoarthritis of the knees. According to researchers of the Ben Gurion University of the Negev, treatment with mineral-rich mud compresses can be used to augment conventional medical therapy.^[46]

Panorama of the Dead Sea from the Mövenpick Resort, Jordan.

Life forms

In the water

The sea is called "dead" because its high salinity prevents macroscopic aquatic organisms, such as fish and aquatic plants, from living 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% to 30% or lower. The Dead Sea temporarily comes to life in the wake of rainy winters. In 1980, after one such rainy winter, the normally dark blue Dead Sea turned red. Researchers from Hebrew University of Jerusalem found the Dead Sea to be teeming with an alga called Dunaliella. Dunaliella in turn nourished carotenoid-containing (red-pigmented) halobacteria, whose presence caused the color change. Since 1980, the Dead Sea basin has been dry and the algae and the bacteria have not returned in measurable numbers.

In 2011 a group of scientists from Be'er Sheva, Israel and Germany discovered fissures in the floor of the Dead Sea by scuba diving and observing the surface. These fissures allow fresh and brackish water to enter the Dead Sea. They sampled biofilms surrounding the fissures and discovered numerous species of bacteria and archaea.^[47]

Fauna and flora around the lake

Many animal species live in the mountains surrounding the Dead Sea. Hikers can see ibex, 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.

History

The delta of the Jordan River was formerly a jungle of papyrus and palm trees. The Jewish historian Flavius Josephus described Jericho as "the most fertile spot in Judea". In Roman and Byzantine times, sugarcane,^{[dubious – discuss]} henna, and sycamore fig all made the lower Jordan valley 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 19th century, Jericho's fertility had disappeared.^{[dubious – discuss]}

Human settlement

There are several small communities near the Dead Sea. These include Ein Gedi, Neve Zohar and the Israeli settlements in the Megilot Regional Council: Kalya, Mitzpe Shalem and Avnat. There is a nature preserve at Ein Gedi, and several Dead Sea hotels are located on the southwest end at Ein Bokek near Neve Zohar. Highway 90 runs north–south on the Israeli side for a total distance of 565 km (351 mi) from Metula on the Lebanese border in the north to its southern terminus at the Egyptian border near the Red Sea port of Eilat.

Potash City is a small community on the Jordanian side of the Dead Sea, and others including Suweima. Highway 65 runs north–south on the Jordanian side from near Jordan's northern tip down past the Dead Sea to the port of Aqaba.

Human history

Biblical period

Dwelling in caves near the Dead Sea is recorded in the Hebrew Bible as having taken place before the Israelites came to Canaan, and extensively at the time of King David.

Just northwest of the Dead Sea is Jericho. Somewhere, perhaps on the southeastern shore, would be the cities mentioned in the Book of Genesis which were said to have been destroyed in the time of Abraham: Sodom and Gomorrah (Genesis 18) and the three other "Cities of the Plain", Admah, Zeboim and Zoar (Deuteronomy 29:23). Zoar escaped destruction when Abraham's nephew Lot escaped to Zoar from Sodom (Genesis 19:21–22). Before the destruction, the Dead Sea was a valley full of natural tar pits, which was called the vale of Siddim. King David was said to have hidden from Saul at Ein Gedi nearby.

In Ezekiel 47:8–9 there is a specific prophecy that the sea will "be healed and made fresh", becoming a normal lake capable of supporting marine life. A similar prophecy is stated in Zechariah 14:8, which says that "living waters will go out from Jerusalem, half of them to the eastern sea and half to the western sea ."

Greek and Roman period

Greek and Jewish writers report that the Nabateans had monopolistic control over the Dead Sea.^[48]

Archaeological evidence shows multiple anchorages existing on both sides of the sea, including in Ein Gedi, Khirbet Mazin (where the ruins of a Hasmonean-era dry dock are located), Numeira and near Masada.^[49][50]

King Herod the Great built or rebuilt several fortresses and palaces on the western bank of the Dead Sea. The most famous was Masada, where in 70 CE a small group of Jewish zealots fled after the fall of the destruction of the Second Temple. The zealots survived until 73 CE, when a siege by the X Legion ended in the deaths by suicide of its 960 inhabitants. Another historically important fortress was Machaerus (מכוור), on the eastern bank, where, according to Josephus, John the Baptist was imprisoned by Herod Antipas and died.^[51]

Again if, as is fabled, there is a lake in Palestine, such that if you bind a man or beast and throw it in it floats and does not sink, this would bear out what we have said. They say that this lake is so bitter and salt that no fish live in it and that if you soak clothes in it and shake them it cleans them. — Aristotle, Meteorology

Also in Roman times, some Essenes 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 ... the town of Engeda" (Natural History, Bk 5.73); and it is therefore a hugely popular but contested hypothesis today, that same Essenes are identical with the settlers at Qumran and that "the Dead Sea Scrolls" discovered during the 20th century in the nearby caves had been their own library.

Josephus identified the Dead Sea in geographic proximity to the ancient Biblical city of Sodom. However, he referred to the lake by its Greek name, Asphaltites.^[52]

Various sects of Jews settled in caves overlooking the Dead Sea. The best known of these are the Essenes of Qumran, who left an extensive library known as the Dead Sea Scrolls.^[53] The town of Ein Gedi, mentioned many times in the Mishna, produced persimmon for the temple's fragrance and for export, using a secret recipe. "Sodomite salt" was an essential mineral for the temple's holy incense, but was said to be dangerous for home use and could cause blindness.^[54] The Roman camps surrounding Masada were built by Jewish slaves receiving water from the towns around the lake. These towns had drinking water from the Ein Feshcha springs and other sweetwater springs in the vicinity.^[55] Zdroj:https://en.wikipedia.org?pojem=Dead_Sea
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