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Black Sea

Sea between Europe and Asia

Top 10 Black Sea related articles

  (Redirected from Black Sea Basin)
Black Sea
The location of the Black Sea
Map of the Black Sea with bathymetry and surrounding relief
LocationEurope and Western Asia
Coordinates44°N 35°E / 44°N 35°E / 44; 35Coordinates: 44°N 35°E / 44°N 35°E / 44; 35
Primary inflowsDanube, Dnieper, Don, Dniester, Kuban
Primary outflowsBosporus
Basin countriesBulgaria, Romania, Ukraine, Russia, Georgia, Turkey
A large number of countries included in drainage basins for inflow rivers
Max. length1,175 km (730 mi)
Surface area436,402 km2 (168,500 sq mi) / 422,000 km2 (Exclude Sea of Azov) and 441,000 km2 (Include shallow Sea of Azov)[1]
Average depth1,253 m (4,111 ft)
Max. depth2,212 m (7,257 ft)
Water volume547,000 km3 (131,200 cu mi)
Black Sea coast of western Georgia, with the skyline of Batumi on the horizon
Coastline of Samsun in Turkey
A sanatorium in Sochi, Russia

The Black Sea is a marginal sea of the Atlantic Ocean lying between Europe and Asia; east of the Balkans in Southeastern Europe, south of the East European Plain in Eastern Europe, west of the Caucasus, and north of Anatolia in Western Asia. It is supplied by major rivers, principally the Danube, Dnieper, and Don. The watersheds of many countries drain into the sea beyond the six that share its coast.[2]

The Black Sea covers 436,400 km2 (168,500 sq mi) (not including the Sea of Azov),[3] a maximum depth of 2,212 m (7,257 ft),[4] and a volume of 547,000 km3 (131,000 cu mi),[5] making it the world's largest inland body of water. Most of its coasts rapidly ascend. These rises are the Pontic Mountains to the south, bar 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 further north.

The longest east-west extent is about 1,175 km (730 mi).[6] Important cities along the coast include Istanbul, Odessa, Varna, Samsun, Sochi, Sevastopol, Constanța, Trabzon, Novorossiysk, Burgas, Batumi, etc.

The Black Sea is bordered by Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine. It 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, generally water is flowing in both directions simultaneously. Denser, more saline water from the Aegean flows into the Black Sea underneath the less dense, fresher outflowing water from 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.

The Black Sea ultimately drains into the Mediterranean Sea, via the Turkish Straits and the Aegean Sea. 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 Turkish Straits connect the Black Sea with the Aegean Sea and comprise the Bosporus, the Sea of Marmara, and the Dardanelles. 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.

Black Sea Intro articles: 41


The International Hydrographic Organization defines the limits of the Black Sea as follows:[7]

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).

Black Sea Extent articles: 4

Exclusive economic zone

Exclusive economic zones in Black Sea (Include Sea of Azov) :[8]

Number Country Area (km2)
1  Turkey 172,484
2  Russia 132,414
3  Ukraine 67,428
4  Bulgaria 35,132
5  Romania 29,756
6  Georgia 22,947
Total Black Sea 460,084

Black Sea Exclusive economic zone articles: 7

Coastline length by country

Coastline length in Black Sea (Include Sea of Azov) :[1]

Number Country Length (km)
1  Russia 2,300
2  Turkey 1,329
3  Ukraine 1,282
4  Bulgaria 354
5  Georgia 310
6  Romania 225
Total Black Sea 5,800

Overview of "Coastline length" article

Basin countries

Black Sea Basin countries, 2-million km2 (0.77-million sq mi) basin and 25 countries :[9][10][11][12][13]

Black Sea Basin countries articles: 18

Largest bays

Largest bays on the Black Sea:[1]

  1. Karkinit Bay,  Ukraine
  2. Burgas Bay,  Bulgaria
  3. Dnieprovski Bay,  Ukraine
  4. Dniestrovski Bay,  Ukraine
  5. Sinop Bay,  Turkey
  6. Samsun Bay,  Turkey

Black Sea Largest bays articles: 6

Largest rivers

Largest rivers flowing into the Black Sea :[1]

Black Sea Largest rivers articles: 25


Most populous urban areas along the Black Sea coastline



Rank City Country Region/County Population (urban)



1 Istanbul  Turkey Istanbul 14,324,240[14]
2 Odessa  Ukraine Odessa 1,003,705
3 Samsun  Turkey Samsun 535,401[15]
5 Varna  Bulgaria Varna 500,076
4 Constanța  Romania Constanța 491,498[16]
6 Sevastopol disputed:  Russia(de facto) /  Ukraine (de jure) Federal city / City with special status 379,200
7 Sochi  Russia Krasnodar Krai 343,334
8 Trabzon  Turkey Trabzon 305,231[17]
9 Novorossiysk  Russia Krasnodar Krai 241,952
10 Burgas  Bulgaria Burgas 223,902[18]
11 Ordu  Turkey Ordu 217,640
12 Batumi  Georgia Adjara 204,156[19]

Black Sea Population articles: 15

Geology and bathymetry

The bay of Sudak, Crimea
Yavuz Sultan Selim Bridge is on the Black Sea connecting Europe to Asia. One of the longest suspension bridges in the world.

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.[20][21][22] 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.[23]

During the Messinian salinity crisis in the neighboring Mediterranean Sea, water levels fell but without drying up the sea.[24]

The ongoing collision between the Eurasian and African plates and westward escape of the Anatolian block along the North Anatolian Fault and East Anatolian Faults dictates the current tectonic regime,[23] which features enhanced subsidence in the Black Sea basin and significant volcanic activity in the Anatolian region.[25] 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 centre of the Black Sea reaches a maximum depth of 2,212 metres (7,257.22 feet) just south of Yalta on the Crimean Peninsula.[26]

The littoral zone of the Black Sea is often referred to as the Pontic littoral or Pontic zone.[27]

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.[28]


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.[29]

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.[30]

Oil and natural gas

The Black Sea contains oil and natural gas resources but exploration in the sea is incomplete. As of 2017, 20 wells are in place. Throughout much of its existence, the Black Sea has had significant oil and gas-forming potential because of significant inflows of sediment and nutrient-rich waters. However, this varies geographically. For example, prospects are poorer off the coast of Bulgaria because of the large influx of sediment from the Danube which obscured sunlight and diluted organic-rich sediments. Many of the discoveries to date have taken place offshore of Romania in the Western Black Sea and only a few discoveries have been made in the Eastern Black Sea.

During the Eocene, the Paratethys Ocean was partially isolated and sea levels fell. During this time sand shed off the rising Balkanide, Pontide and Caucasus mountains trapped organic material in the Maykop Suite of rocks through the Oligocene and early Miocene. Natural gas appears in rocks deposited in the Miocene and Pliocene by the paleo-Dnieper and pale-Dniester rivers, or in deep-water Oligocene-age rocks. Serious exploration began in 1999 with two deep-water wells, Limanköy-1 and Limanköy-2, drilled in Turkish waters. Next, the HPX (Hopa)-1 deepwater well targeted late Miocene sandstone units in Achara-Trialet fold belt (also known as the Gurian fold belt) along the Georgia-Turkey maritime border. Although geologists inferred that these rocks might have hydrocarbons that migrated from the Maykop Suite, the well was unsuccessful. No more drilling happened for five years after the HPX-1 well. Then in 2010, Sinop-1 targeted carbonate reservoirs potentially charged from the nearby Maykop Suite on the Andrusov Ridge, but the well-struck only Cretaceous volcanic rocks. Yassihöyük-1 encountered similar problems. Other Turkish wells, Sürmene-1 and Sile-1 drilled in the Eastern Black Sea in 2011 and 2015 respectively tested four-way closures above Cretaceous volcanoes, with no results in either case. A different Turkish well, Kastamonu-1 drilled in 2011 did successfully find thermogenic gas in Pliocene and Miocene shale-cored anticlines in the Western Black Sea. A year later in 2012, Romania drilled Domino-1 which struck gas prompting the drilling of other wells in the Neptun Deep. In 2016, the Bulgarian well Polshkov-1 targeted Maykop Suite sandstones in the Polshkov High and Russia is in the process of drilling Jurassic carbonates on the Shatsky Ridge as of 2018.[31]

In August 2020, Turkey found 320 billion cubic metres (11 trillion cubic feet) of natural gas in the biggest ever discovery in the Black Sea, and hoped to begin production by 2023. The Turkish drilling ship Fatih, had been carrying out exploration operations in the Tuna-1 sector in the western Black Sea for the past month. The sector is near where Romania has also found gas reserves.[32]

Black Sea Geology and bathymetry articles: 54


Coast of the Black Sea at Ordu
Sunset on the Black Sea at Laspi, Crimea
The estuary of the Veleka in the Black Sea. Longshore drift has deposited sediment along the shoreline which has led to the formation of a spit, Sinemorets, Bulgaria
The Black Sea near Constanța, Romania

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:[33]

Such names have not yet been shown conclusively to predate the 13th century.[34]

In Greece, the historical name "Euxine Sea", which holds a different meaning (see below), is still widely used:

Historical names and etymology

The principal Greek name Póntos Áxeinos is generally accepted to be a rendering of Iranian word *axšaina- (dark colored), compare Avestan axšaēna- (dark colored), Old Persian axšaina- (turquoise colored), Middle Persian axšēn/xašēn (blue), and New Persian xašīn (blue), as well as Ossetic œxsīn (dark gray).[34] Ancient Greek voyagers adopted the name as Á-xe(i)nos, identified with the Greek word áxeinos (inhospitable).[34] 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.[34]

Strabo's Geographica (1.2.10) reports that in antiquity, the Black Sea was often simply called "the Sea" (ὁ πόντος ho Pontos). He also thought the Black Sea was called "inhospitable" before Greek colonization for its difficult navigation and hostile barbarian natives (7.3.6), and that the name was changed to "hospitable" after the Milesians colonized the Pontus region of the southern shoreline, bringing it within Greek civilization.

Popular supposition derives "Black Sea" from the dark color of the water or climatic conditions. Rather, it referred to a system of 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.[34] Hence "Black Sea" meant "Northern Sea", while "Red Sea" from the time of Herodotus (c. 450 BC) designated the waters south of the known world, the Indian Ocean together with today's Persian Gulf and Red Sea. According to this scheme, the name could not have originated with the Scythians, who principally roamed north of the sea, but only with a people living between the northern (black) and southern (red) seas: this points to the Achaemenids (550–330  BC).[34]

In the Greater Bundahishn, a Middle Persian Zoroastrian scripture, the Black Sea is called Siyābun.[35] In the tenth-century Persian geography book Hudud al-'Alam, the Black Sea is called Sea of the Georgians (daryā-yi Gurz).[36] The Georgian Chronicles use the name zğua sperisa ზღუა სპერისა (Sea of Speri) after the Kartvelian tribe of Speris or Saspers.[37] Other modern names such as Chyornoye more and Karadeniz, originated in the 13th century.[34] A 1570 map Asiae Nova Descriptio from Abraham Ortelius's Theatrum Orbis Terrarum labels the sea Mar Maggior (Great Sea), compare Latin mare major.[38]

English writers of the 18th century often used Euxine Sea (/ˈjksɪn/ or /ˈjkˌsn/), for example Edward Gibbon throughout his Decline and Fall of the Roman Empire.[39] During the Ottoman Empire, it was called either Bahr-e Siyah or Karadeniz, both meaning "Black Sea" in Turkish.[40]

Black Sea Name articles: 49