The Black Sea is a marginal sea located between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bordered by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is supplied by major rivers, principally the Danube, Dnieper and Dniester. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe.
The Black Sea, not including the Sea of Azov, covers 436,400 km2 (168,500 sq mi), has a maximum depth of 2,212 m (7,257 ft), and a volume of 547,000 km3 (131,000 cu mi).
Most of its coasts ascend rapidly.
These rises are the Pontic Mountains to the south, the southwest-facing peninsulas, the Caucasus Mountains to the east, and the Crimean Mountains to the mid-north.
In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end of the Balkan Mountains; and the Dobruja Plateau considerably farther north. The longest east–west extent is about 1,175 km (730 mi). Important cities along the coast include (clockwise from the Bosporus) the northern suburbs of Istanbul, Burgas, Varna, Constanța, Odesa, Yevpatoria, Sevastopol, Yalta, Kerch, Novorossiysk, Sochi, Poti, Batumi, Rize, Trabzon, Ordu, Samsun and Zonguldak.
The Black Sea has a positive water balance, with an annual net outflow of 300 km3 (72 cu mi) per year through the Bosporus and the Dardanelles into the Aegean Sea. While the net flow of water through the Bosporus and Dardanelles (known collectively as the Turkish Straits) is out of the Black Sea, water generally flows in both directions simultaneously: Denser, more saline water from the Aegean flows into the Black Sea underneath the less dense, fresher water that flows out of the Black Sea. This creates a significant and permanent layer of deep water that does not drain or mix and is therefore anoxic. This anoxic layer is responsible for the preservation of ancient shipwrecks which have been found in the Black Sea, which ultimately drains into the Atlantic Ocean, via the Turkish Straits and the Aegean Sea into the Mediterranean Sea, and from it to the Atlantic proper through the Strait of Gibraltar. The Bosporus strait connects it to the small Sea of Marmara which in turn is connected to the Aegean Sea via the strait of the Dardanelles. To the north, the Black Sea is connected to the Sea of Azov by the Kerch Strait.
The water level has varied significantly over geological time. Due to these variations in the water level in the basin, the surrounding shelf and associated aprons have sometimes been dry land. At certain critical water levels, connections with surrounding water bodies can become established. It is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the World Ocean. During geological periods when this hydrological link was not present, the Black Sea was an endorheic basin, operating independently of the global ocean system (similar to the Caspian Sea today). Currently, the Black Sea water level is relatively high; thus, water is being exchanged with the Mediterranean. The Black Sea undersea river is a current of particularly saline water flowing through the Bosporus Strait and along the seabed of the Black Sea, the first of its kind discovered.
Name
Modern names
Current names of the sea are usually equivalents of the English name "Black Sea", including these given in the countries bordering the sea:
Abkhaz: Амшын Еиқәа, romanized: Amŝən Ejkʷa, IPA: [ɑmʂɨn ɛjkʷʰɑ]
Adyghe: Хы Шӏуцӏэ, romanized: Xə Šʷʼucʼɛ, IPA: [xɘ ʃʷʼtsʼɜ]
Armenian: Սեւ ծով, romanized: Sev cov, IPA: [sɛv t͡sɔv]
Azerbaijani: Qara dəniz, IPA: [ɡɑˈɾɑ dæˈniz]
Bulgarian: Чeрно морe, romanized: Čérno moré, IPA: [ˈt͡ʃɛrno moˈrɛ]
Crimean Tatar: Qara deñiz, Къара денъиз, IPA: [qɑrɑ deŋiz]
Gagauz: Kara deniz
Georgian: შავი ზღვა, romanized: Shavi Zghva, IPA: [ʃavi zʁʷa]
Laz and Mingrelian: უჩა ზუღა, romanized: Ucha Zugha, IPA: [ˈutʃä ˈzuɣä], or simply ზუღა, Zugha, IPA: [ˈzuɣä], "Sea"
Persian: دریای سیاه, romanized: daryā-ye siyāh
Romanian: Marea Neagră, pronounced [ˈmare̯a ˈne̯aɡrə]
Russian: Чёрное мо́ре, romanized: Chornoye more, IPA: [ˈtɕɵrnəjɪ ˈmorʲɪ]
Turkish: Karadeniz, IPA: [kaˈɾadeniz]
Ukrainian: Чо́рне мо́ре, romanized: Chorne more, IPA: [ˈtʃɔrne ˈmɔre]
Such names have not yet been shown conclusively to predate the 13th century.
In Greece, the historical name "Euxine Sea", which holds a different literal meaning (see below), is still widely used:
Greek: Εύξεινος Πόντος, romanized: Éfxinos Póndos, lit. 'Hospitable Sea', [ˈefksinos ˈpondos]; the name Μαύρη Θάλασσα, Mávri Thálassa, 'Black Sea', [ˈmavɾi ˈθalasa], is used, but is much less common.
The Black Sea is one of four seas named in English after common color terms – the others being the Red Sea, the White Sea and the Yellow Sea.
Historical names and etymology
The earliest known name of the Black Sea is the Sea of Zalpa, so called by both the Hattians and their conquerors, the Hittites. The Hattic city of Zalpa was "situated probably at or near the estuary of the Marrassantiya River, the modern Kızıl Irmak, on the Black Sea coast."
The principal Greek name Póntos Áxeinos is generally accepted to be a rendering of the Iranian word *axšaina- ("dark colored"). Ancient Greek voyagers adopted the name as Á-xe(i)nos, identified with the Greek word áxeinos (inhospitable). The name Πόντος Ἄξεινος Póntos Áxeinos (Inhospitable Sea), first attested in Pindar (c. 475 BC), was considered an ill omen and was euphemized to its opposite, Εὔξεινος Πόντος Eúxeinos Póntos (Hospitable Sea), also first attested in Pindar. This became the commonly used designation in Greek, although in mythological contexts the "true" name Póntos Áxeinos remained favored.
Strabo's Geographica (1.2.10) reports that in antiquity, the Black Sea was often simply called "the Sea" (ὁ πόντος ho Pontos). He thought that the sea was called the "Inhospitable Sea" Πόντος Ἄξεινος Póntos Áxeinos by the inhabitants of the Pontus region of the southern shoreline before Greek colonization due to its difficult navigation and hostile barbarian natives (7.3.6), and that the name was changed to "hospitable" after the Milesians colonized the region, bringing it into the Greek world.
Popular supposition derives "Black Sea" from the dark color of the water or climatic conditions. Some scholars understand the name to be derived from a system of Turkic color symbolism representing the cardinal directions, with black or dark for north, red for south, white for west, and green or light blue for east. Hence, "Black Sea" meant "Northern Sea". According to this scheme, the name could only have originated with a people living between the northern (black) and southern (red) seas: this points to the Achaemenids (550–330 BC). This interpretation, however, has been contested.
In the Greater Bundahishn, a Middle Persian Zoroastrian scripture, the Black Sea is called Siyābun. In the tenth-century Persian geography book Hudud al-'Alam, the Black Sea is called Georgian Sea (daryā-yi Gurz). The Georgian Chronicles use the name zğua sperisa ზღუა სპერისა (Sea of Speri) after the Kartvelian tribe of Speris or Saspers. Other modern names such as Chyornoye more and Karadeniz (both meaning Black Sea) originated during the 13th century. A 1570 map Asiae Nova Descriptio from Abraham Ortelius's Theatrum Orbis Terrarum labels the sea Mar Maggior (Great Sea), compare Latin Mare major.
English writers of the 18th century often used Euxine Sea ( or ). During the Ottoman Empire, it was called either Bahr-i Siyah (Perso-Arabic) or Karadeniz (Ottoman Turkish), both meaning "Black Sea".
Geography
The International Hydrographic Organization defines the limits of the Black Sea as follows:
On the Southwest. The Northeastern limit of the Sea of Marmara [A line joining Cape Rumili with Cape Anatoli (41°13'N)].
In the Kertch Strait. A line joining Cape Takil and Cape Panaghia (45°02'N).The area surrounding the Black Sea is commonly referred to as the Black Sea Region. Its northern part lies within the Chernozem belt (black soil belt) which goes from eastern Croatia (Slavonia), along the Danube (northern Serbia, northern Bulgaria (Danubian Plain) and southern Romania (Wallachian Plain) to northeast Ukraine and further across the Central Black Earth Region and southern Russia into Siberia.
The littoral zone of the Black Sea is often referred to as the Pontic littoral or Pontic zone.
The largest bays of the Black Sea are Karkinit Bay in Ukraine; the Gulf of Burgas in Bulgaria; Dnieprovska Gulf and Dniestrovsky Liman, both in Ukraine; and Sinop Bay and Samsun Bay, both in Turkey.
Coastline and exclusive economic zones
Drainage basin
The largest rivers flowing into the Black Sea are:
These rivers and their tributaries comprise a 2-million km2 (0.77-million sq mi) Black Sea drainage basin that covers wholly or partially 24 countries:
Islands
Some islands in the Black Sea belong to Bulgaria, Romania, Turkey, and Ukraine:
Climate
Short-term climatic variation in the Black Sea region is significantly influenced by the operation of the North Atlantic oscillation, the climatic mechanisms resulting from the interaction between the north Atlantic and mid-latitude air masses. While the exact mechanisms causing the North Atlantic Oscillation remain unclear, it is thought the climate conditions established in western Europe mediate the heat and precipitation fluxes reaching Central Europe and Eurasia, regulating the formation of winter cyclones, which are largely responsible for regional precipitation inputs and influence Mediterranean sea surface temperatures (SSTs).
The relative strength of these systems also limits the amount of cold air arriving from northern regions during winter. Other influencing factors include the regional topography, as depressions and storm systems arriving from the Mediterranean are funneled through the low land around the Bosporus, with the Pontic and Caucasus mountain ranges acting as waveguides, limiting the speed and paths of cyclones passing through the region.
Geology and bathymetry
The Black Sea is divided into two depositional basins—the Western Black Sea and Eastern Black Sea—separated by the Mid-Black Sea High, which includes the Andrusov Ridge, Tetyaev High, and Archangelsky High, extending south from the Crimean Peninsula. The basin includes two distinct relict back-arc basins which were initiated by the splitting of an Albian volcanic arc and the subduction of both the Paleo- and Neo-Tethys oceans, but the timings of these events remain uncertain. Arc volcanism and extension occurred as the Neo-Tethys Ocean subducted under the southern margin of Laurasia during the Mesozoic. Uplift and compressional deformation took place as the Neotethys continued to close. Seismic surveys indicate that rifting began in the Western Black Sea in the Barremian and Aptian followed by the formation of oceanic crust 20 million years later in the Santonian. Since its initiation, compressional tectonic environments led to subsidence in the basin, interspersed with extensional phases resulting in large-scale volcanism and numerous orogenies, causing the uplift of the Greater Caucasus, Pontides, southern Crimean Peninsula and Balkanides mountain ranges.
During the Messinian salinity crisis in the neighboring Mediterranean Sea, water levels fell but without drying up the sea. The collision between the Eurasian and African plates and the westward escape of the Anatolian block along the North Anatolian and East Anatolian faults dictates the current tectonic regime, which features enhanced subsidence in the Black Sea basin and significant volcanic activity in the Anatolian region. These geological mechanisms, in the long term, have caused the periodic isolations of the Black Sea from the rest of the global ocean system.
The large shelf to the north of the basin is up to 190 km (120 mi) wide and features a shallow apron with gradients between 1:40 and 1:1000. The southern edge around Turkey and the eastern edge around Georgia, however, are typified by a narrow shelf that rarely exceeds 20 km (12 mi) in width and a steep apron that is typically 1:40 gradient with numerous submarine canyons and channel extensions. The Euxine abyssal plain in the center of the Black Sea reaches a maximum depth of 2,212 metres (7,257.22 feet) just south of Yalta on the Crimean Peninsula.
Chronostratigraphy
The Paleo-Euxinian is described by the accumulation of eolian silt deposits (related to the Riss glaciation) and the lowering of sea levels (MIS 6, 8 and 10). The Karangat marine transgression occurred during the Eemian Interglacial (MIS 5e). This may have been the highest sea levels reached in the late Pleistocene. Based on this some scholars have suggested that the Crimean Peninsula was isolated from the mainland by a shallow strait during the Eemian Interglacial.
The Neoeuxinian transgression began with an inflow of waters from the Caspian Sea. Neoeuxinian deposits are found in the Black Sea below −20 m (−66 ft) water depth in three layers. The upper layers correspond with the peak of the Khvalinian transgression, on the shelf shallow-water sands and coquina mixed with silty sands and brackish-water fauna, and inside the Black Sea Depression hydrotroilite silts. The middle layers on the shelf are sands with brackish-water mollusc shells. Of continental origin, the lower level on the shelf is mostly alluvial sands with pebbles, mixed with less common lacustrine silts and freshwater mollusc shells. Inside the Black Sea Depression they are terrigenous non-carbonate silts, and at the foot of the continental slope turbidite sediments.
Hydrology
The Black Sea is the world's largest body of water with a meromictic basin. The deep waters do not mix with the upper layers of water that receive oxygen from the atmosphere. As a result, over 90% of the deeper Black Sea volume is anoxic water. The Black Sea's circulation patterns are primarily controlled by basin topography and fluvial inputs, which result in a strongly stratified vertical structure. Because of the extreme stratification, it is classified as a salt wedge estuary.
Inflow from the Mediterranean Sea through the Dardanelles and Bosporus has a higher salinity and density than the outflow, creating the classic estuarine circulation. This means that the inflow of dense water from the Mediterranean occurs at the bottom of the basin while the outflow of fresher Black Sea surface-water into the Sea of Marmara occurs near the surface. The outflow is 16,000 cubic metres per second (570,000 cubic feet per second) or around 500 cubic kilometres per year (120 cubic miles per year), and the inflow is 11,000 m3/s (390,000 cu ft/s) or around 350 km3/a (84 cu mi/a).