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88-759: Paleo-Tethys was a precursor to the Tethys Ocean (also called the Neo-Tethys) which was located between Gondwana and the Hunic terranes (continental fragments that broke-off Gondwana and moved north). It opened as the Proto-Tethys Ocean subducted under these terranes and closed as the Cimmerian terranes (that also broke-off Gondwana and moved north) gave way to the Tethys Ocean. Confusingly,

176-527: A halocline that stops at the Cold Intermediate Layer (CIL). This layer is composed of cool, salty surface waters, which are the result of localized atmospheric cooling and decreased fluvial input during the winter months. It is the remnant of the winter surface mixed layer. The base of the CIL is marked by a major pycnocline at about 100–200 metres (330–660 ft), and this density disparity

264-597: 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 km (168,500 sq mi), has a maximum depth of 2,212 m (7,257 ft), and a volume of 547,000 km (131,000 cu mi). Most of its coasts ascend rapidly. These rises are the Pontic Mountains to the south, bar the southwest-facing peninsulas,

352-541: A marked vertical stratification and a warm, shallow mixed layer. Day length and insolation intensity also control the extent of the photic zone . Subsurface productivity is limited by nutrient availability, as the anoxic bottom waters act as a sink for reduced nitrate , in the form of ammonia . The benthic zone also plays an important role in Black Sea nutrient cycling, as chemosynthetic organisms and anoxic geochemical pathways recycle nutrients which can be upwelled to

440-589: 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 Bosporus and Dardanelles 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

528-433: A threat to health—and perhaps even life—for people living on the Black Sea coast. There have been isolated reports of flares on the Black Sea occurring during thunderstorms, possibly caused by lightning igniting combustible gas seeping up from the sea depths. The Black Sea supports an active and dynamic marine ecosystem, dominated by species suited to the brackish , nutrient-rich, conditions. As with all marine food webs,

616-529: A very thick convective bottom layer. 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 discovery of the river, announced on August 1, 2010, was made by scientists at the University of Leeds and is the first of its kind to be identified. The undersea river stems from salty water spilling through

704-496: A weaker mixed assemblage of community development below the seasonal thermocline during summer months, and surface-intensified autumn production. This pattern of productivity is augmented by an Emiliania huxleyi bloom during the late spring and summer months. Since the 1960s, rapid industrial expansion along the Black Sea coastline and the construction of a major dam on the Danube have significantly increased annual variability in

792-631: Is a marginal mediterranean sea lying between Europe and Asia , east of the Balkans , south of the East European Plain , west of the Caucasus , and north of Anatolia . It is bounded 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

880-603: Is a part of the original Cimmerian continent that formed the southern boundary of the Paleo-Tethys.) The Paleo-Tethys Ocean sat where the Indian Ocean and Southern Asia are now located. The Equator ran the length of the sea, giving it a tropical climate. The shores and islands probably supported dense coal forests . Tethys Ocean The Tethys Ocean ( / ˈ t iː θ ɪ s , ˈ t ɛ -/ TEETH -iss, TETH - ; Greek : Τηθύς Tēthús ), also called

968-753: 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

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1056-719: 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

1144-590: Is subject to interannual variability. Outside of the Rim Current, numerous quasi-permanent coastal eddies are formed as a result of upwelling around the coastal apron and "wind curl" mechanisms. The intra-annual strength of these features is controlled by seasonal atmospheric and fluvial variations. During the spring, the Batumi eddy forms in the southeastern corner of the sea. Beneath the surface waters—from about 50 to 100 metres (160 to 330 ft)—there exists

1232-460: Is the major mechanism for isolation of the deep water. Below the pycnocline is the Deep Water mass, where salinity increases to 22.3 PSU and temperatures rise to around 8.9 °C (48.0 °F). The hydrochemical environment shifts from oxygenated to anoxic, as bacterial decomposition of sunken biomass utilizes all of the free oxygen. Weak geothermal heating and long residence time create

1320-640: Is what is thought to have allowed for upwelling in the Arabian Sea and led to the establishment of the modern South Asian Monsoon . It also caused major modifications to the functioning of the AMOC and ACC . During the Oligocene (33.9 to 23 Mya), large parts of central and eastern Europe were covered by a northern branch of the Tethys Ocean, called the Paratethys . The Paratethys was separated from

1408-689: The Alleghenian orogeny , in Europe the Variscan orogeny . The Rheic Ocean had completely disappeared, and the western Paleo-Tethys was closing. By the Late Permian , the small elongated Cimmerian plate (today's crust of Turkey , Iran , Tibet and parts of South-East Asia ) broke away from Gondwana (now part of Pangaea ). South of the Cimmerian continent a new ocean, the Tethys Ocean ,

1496-587: The Bosporus ) Burgas , Varna , Constanța , Odesa , Sevastopol , Novorossiysk , Sochi , Poti , Batumi , Trabzon and Samsun . The Black Sea has a positive water balance , with an annual net outflow of 300 km (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

1584-749: 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

1672-917: 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; Dnieprovski Bay and Dniestrovski Bay, both in Ukraine; and Sinop Bay and Samsun Bay, both in Turkey. The largest rivers flowing into

1760-748: 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

1848-513: The Paratethys when the Alpine front was still 100 km (62 mi) farther south. In 1885, the Austrian palaeontologist Melchior Neumayr deduced the existence of the Tethys Ocean from Mesozoic marine sediments and their distribution, calling his concept Zentrales Mittelmeer ( lit.   ' Central Mediterranean Sea ' ) and described it as a Jurassic seaway, which extended from

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1936-700: The Rheic Ocean , which existed to the west of them in the Silurian Period. To the north of the Tethys, the then-land mass is called Angaraland and to the south of it, it is called Gondwanaland . From the Ediacaran (600  Mya ) into the Devonian (360 Mya ), the Proto-Tethys Ocean existed and was situated between Baltica and Laurentia to the north and Gondwana to the south. From

2024-632: 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

2112-777: The Silurian (440 Mya ) through the Jurassic periods, the Paleo-Tethys Ocean existed between the Hunic terranes and Gondwana. Over a period of 400 million years, continental terranes intermittently separated from Gondwana in the Southern Hemisphere to migrate northward to form Asia in the Northern Hemisphere. About 250 Mya, during the Triassic , a new ocean began forming in

2200-710: The Tethys Sea or the Neo-Tethys , was a prehistoric ocean during much of the Mesozoic Era and early-mid Cenozoic Era . It was the predecessor to the modern Indian Ocean , the Mediterranean Sea , and the Eurasian inland marine basins (primarily represented today by the Black Sea and Caspian Sea ). During the early Mesozoic, as Pangaea broke up, the Tethys Ocean was defined as the ocean located between

2288-516: 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

2376-643: 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 ( / ˈ j uː k s ɪ n / or / ˈ j uː k ˌ s aɪ n / ). During the Ottoman Empire , it was called either Bahr-e Siyah ( Perso-Arabic ) or Karadeniz ( Ottoman Turkish ), both meaning "Black Sea". The International Hydrographic Organization defines

2464-490: The 1960s, "fixist" geologists, however, regarded Tethys as a composite trough, which evolved through a series of orogenic cycles. They used the terms 'Paleotethys', 'Mesotethys', and 'Neotethys' for the Caledonian , Variscan , and Alpine orogenies, respectively. In the 1970s and 1980s, these terms and 'Proto-Tethys', were used in different senses by various authors, but the concept of a single ocean wedging into Pangea from

2552-820: The Aralo-Caspian Formation extending from close to the Danube delta across Crimea, up the east side of the Volga river to Samara, then south of the Urals to beyond the Aral Sea. Brackish and upper freshwater components (OSM) of the Miocene are now known to extend through the North Alpine foreland basin and onto the Swabian Jura with thickness of up to 250 m (820 ft); these were deposited in

2640-582: The Black Sea Depression they are terrigenous non-carbonate silts , and at the foot of the continental slope turbidite sediments. 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

2728-404: The Black Sea are: These rivers and their tributaries comprise a 2-million km (0.77-million sq mi) Black Sea drainage basin that covers wholly or partially 24 countries: Unrecognised states: Some islands in the Black Sea belong to Bulgaria, Romania, Turkey, and Ukraine: Short-term climatic variation in the Black Sea region is significantly influenced by the operation of

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2816-585: The Black Sea features a range of trophic groups, with autotrophic algae, including diatoms and dinoflagellates , acting as primary producers. The fluvial systems draining Eurasia and central Europe introduce large volumes of sediment and dissolved nutrients into the Black Sea, but the distribution of these nutrients is controlled by the degree of physiochemical stratification, which is, in turn, dictated by seasonal physiographic development. During winter, strong wind promotes convective overturning and upwelling of nutrients, while high summer temperatures result in

2904-510: 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

2992-478: 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

3080-503: 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. Current names of

3168-525: The Bosporus Strait from the Mediterranean Sea into the Black Sea, where the water has a lower salt content. Because of the anoxic water at depth, organic matter, including anthropogenic artifacts such as boat hulls, are well preserved. During periods of high surface productivity, short-lived algal blooms form organic rich layers known as sapropels . Scientists have reported an annual phytoplankton bloom that can be seen in many NASA images of

3256-483: The Bosporus is located at 36.5 m (120 ft) below present sea level (deepest spot of the shallowest cross-section in the Bosporus, located in front of Dolmabahçe Palace ) and has a wet section of around 38,000 m (410,000 sq ft). Inflow and outflow current speeds are averaged around 0.3 to 0.4 m/s (1.0 to 1.3 ft/s), but much higher speeds are found locally, inducing significant turbulence and vertical shear. This allows for turbulent mixing of

3344-698: The Caribbean to the Himalayas. In 1893, the Austrian geologist Eduard Suess proposed the hypothesis that an ancient and extinct inland sea had once existed between Laurasia and the continents which formed Gondwana II. He named it the Tethys Sea after the Greek sea goddess Tethys. He provided evidence for his theory using fossil records from the Alps and Africa. He proposed the concept of Tethys in his four-volume work Das Antlitz der Erde ( The Face of

3432-403: The Early Carboniferous however, a subduction zone developed south of the European Hunic terranes consuming Paleo-Tethys oceanic crust . Gondwana started moving north, and in the process the western part of the Paleo-Tethys would close. In the Carboniferous continental collision took place between the Old Red Sandstone Continent and the European Hunic terrane, in North America this is called

3520-425: The Earth ). In the following decades during the 20th century, " mobilist " geologists such as Uhlig (1911), Diener (1925), and Daque (1926) regarded Tethys as a large trough between two supercontinents which lasted from the late Palaeozoic until continental fragments derived from Gondwana obliterated it. After World War II , Tethys was described as a triangular ocean with a wide eastern end. From 1920s to

3608-431: The Eurasian plate, which created new borders to the ocean, a land barrier to the flow of currents between the Indian and Mediterranean basins, and the orogenies of the Alpide belt (including the Alps , Himalayas , Zagros , and Caucasus Mountains ). All of these geological events, in addition to a drop in sea level rise from Antarctic glaciation, brought an end to the Tethys as it previously existed, fragmenting it into

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3696-408: The Indian Ocean, the Mediterranean Sea, and the Paratethys . It was preceded by the Paleo-Tethys Ocean , which lasted between the Cambrian and the Early Triassic , while the Neotethys formed during the Late Triassic and lasted in some form up to the Oligocene – Miocene boundary (about 24–21 million years ago) when it completely closed. A portion known as the Paratethys was isolated during

3784-448: The N:P:Si ratio in the basin. Coastal areas, accordingly, have seen an increase in the frequency of monospecific phytoplankton blooms, with diatom-bloom frequency increasing by a factor of 2.5 and non-diatom bloom frequency increasing by a factor of 6. The non-diatoms, such as the prymnesiophytes Emiliania huxleyi (coccolithophore), Chromulina sp., and the Euglenophyte Eutreptia lanowii , can out-compete diatom species because of

3872-419: The Neo-Tethys is sometimes defined as the ocean south of a hypothesised mid-ocean ridge separating Greater India from Asia, in which case the ocean between Cimmeria and this hypothesised ridge is called the Meso-Tethys, i.e. the "Middle-Tethys". The so-called Hunic terranes are divided into the European Hunic (today the crust under parts of Europe – called Armorica – and Iberia ) and Asiatic Hunic (today

3960-421: The Oligocene (34 million years ago) and lasted up to the Pliocene (about 5 million years ago), when it largely dried out. The modern inland seas of Europe and Western Asia, namely the Black Sea and Caspian Sea, are remnants of the Paratethys Sea. The sea is named after Tethys , who, in ancient Greek mythology, is a water goddess, a sister and consort of Oceanus , mother of the Oceanid sea nymphs and of

4048-404: The Paleo-Tethys and Tethys resulted in the break-up. In the first scenario, mantle plumes caused the opening of the Atlantic and the break-up of Pangaea and the closure of the Tethyan domain was one of the consequences of this process; in the other scenario, the longitudinal forces that closed the Tethyan domain were transmitted latitudinally in what is today the Mediterranean region, resulting in

4136-427: The Paleo-Tethys formerly rested. During the Jurassic period about 150 Mya, Cimmeria finally collided with Laurasia and stalled, so the ocean floor behind it buckled under , forming the Tethys Trench . Water levels rose, and the western Tethys shallowly covered significant portions of Europe, forming the first Tethys Sea. Around the same time, Laurasia and Gondwana began drifting apart , opening an extension of

4224-464: The Rim Current. The Rim Current has a maximum velocity of about 50–100 cm/s (20–39 in/s). Within this feature, two smaller cyclonic gyres operate, occupying the eastern and western sectors of the basin. The Eastern and Western Gyres are well-organized systems in the winter but dissipate into a series of interconnected eddies in the summer and autumn. Mesoscale activity in the peripheral flow becomes more pronounced during these warmer seasons and

4312-400: The Tethys Sea between them which today is the part of the Atlantic Ocean between the Mediterranean and the Caribbean . As North and South America were still attached to the rest of Laurasia and Gondwana, respectively, the Tethys Ocean in its widest extension was part of a continuous oceanic belt running around the Earth between about latitude 30°N and the Equator . Thus, ocean currents at

4400-417: The Tethys were eventually closed off in what is now the Middle East during the Miocene , as a consequence of the northern migration of Africa/Arabia and global sea levels falling due to the concurrent formation of the Antarctic Ice Sheet . This decoupling occurred in two steps, first around 20 Mya and another around 14 Mya. The complete closure of the Tethys led to a global reorganization of currents, and

4488-409: The Tethys with the Arctic Ocean . As theories have improved, scientists have extended the "Tethys" name to refer to three similar oceans that preceded it, separating the continental terranes: in Asia, the Paleo-Tethys (Devonian–Triassic), Meso-Tethys (late Early Permian –Late Cretaceous), and Ceno-Tethys (Late-Triassic–Cenozoic) are recognized. None of the Tethys oceans should be confused with

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4576-417: The Tethys with the formation of the Alps, Carpathians , Dinarides , Taurus , and Elburz mountains during the Alpine orogeny . During the late Miocene , the Paratethys gradually disappeared, and became an isolated inland sea. Separation from the wider Tethys during the early Miocene initially led to a boost in primary productivity for the Paratethys, but this gave way to a total ecosystem collapse during

4664-409: 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. The Black Sea

4752-413: The ancient continents of Gondwana and Laurasia . After the opening of the Indian and Atlantic oceans during the Cretaceous Period and the breakup of these continents over the same period, it came to be defined as the ocean bordered by the continents of Africa, Eurasia, India, and Australasia. During the early-mid Cenozoic, the Indian, African, Australian and Arabian plates moved north and collided with

4840-424: 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). In the Greater Bundahishn , a Middle Persian Zoroastrian scripture,

4928-412: 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 . 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

5016-417: The commonly used designation in Greek, although in mythological contexts the "true" name Póntos Áxeinos remained favoured. 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

5104-407: The crust of parts of southern Asia). A large transform fault separated the two terranes . The role the Paleo-Tethys played in the supercontinent cycle , and especially the break-up of Pangaea , is unresolved. Some geologists argue that the opening of the North Atlantic was triggered by the subduction of Panthalassa under the western margins of the Americas while other argue that the closure of

5192-423: The early Cenozoic, the Tethys Ocean could be divided into three sections: the Mediterranean Tethys (the direct predecessor to the Mediterranean Sea), the Peri-Tethys (a vast inland sea that covered much of eastern Europe and central Asia, and the direct predecessor to the Paratethys Sea), and the Indian Tethys (the direct predecessor to the Indian Ocean). The Turgai Strait extended out of the Peri-Tethys, connecting

5280-582: The east, roughly where Suess first proposed it, remained. In the 1960s, the theory of plate tectonics became established, and Suess's "sea" could clearly be seen to have been an ocean. Plate tectonics provided an explanation for the mechanism by which the former ocean disappeared: oceanic crust can subduct under continental crust . Tethys was considered an oceanic plate by Smith (1971); Dewey, Pitman, Ryan and Bonnin (1973); Laubscher and Bernoulli (1973); and Bijou-Duval, Dercourt and Pichon (1977). Black Sea Unrecognised states: The Black Sea

5368-404: The formation of a small Rhenhercynian Ocean which lasted until Late Carboniferous time. In the Early Devonian , the eastern part of Paleo-Tethys opened up, when the Asiatic Hunic terranes, including the North and South China microcontinents, moved northward. These events caused Proto-Tethys Ocean to shrink until the Late Carboniferous , when the Chinese blocks collided with Siberia . In

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5456-441: 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

5544-411: The historic æra, a vast region of Europe and Asia was covered by a Mediterranean Sea of brackish water, of which the present Caspian is the diminished type. ... To render the distinction between these accumulations and all others clear and unambiguous, we have adopted the term Aralo-Caspian, first applied in a geographical sense, by our great precursor Humboldt, to this region of the globe. ... Judging from

5632-427: The initial opening of the Atlantic. The Paleo-Tethys Ocean began to form when back-arc spreading separated the European Hunic terranes from Gondwana in the late Ordovician , to begin moving toward Euramerica (also known as the Old Red Sandstone Continent) in the north. In the process, the plate under the Rheic Ocean between Euramerica and the European Hunic terranes subducted and rifts in this plate resulted in

5720-518: The late 1980s. Additionally, an alien species—the warty comb jelly ( Mnemiopsis leidyi )—established itself in the basin, exploding from a few individuals to an estimated biomass of one billion metric tons. The change in species composition in Black Sea waters also has consequences for hydrochemistry, as calcium-producing coccolithophores influence salinity and pH, although these ramifications have yet to be fully quantified. In central Black Sea waters, silicon levels also reduced significantly, due to

5808-412: The late Miocene as a result of rapid dissolution of carbonate . In Chapter 13 of his 1845 book, Roderick Murchison described a distinctive formation extending from the Black Sea to the Aral Sea in which the creatures differed from those of the purely marine period that preceded them. The Miocene deposits of Crimea and Taman (south of the Sea of Azov ) are identical with formations surrounding

5896-407: The limited availability of silicon, a necessary constituent of diatom frustules. As a consequence of these blooms, benthic macrophyte populations were deprived of light, while anoxia caused mass mortality in marine animals. Overfishing during the 1970s further compounded the decline in macrophytes, while the invasive ctenophore Mnemiopsis reduced the biomass of copepods and other zooplankton in

5984-462: 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

6072-406: The masses of water now separated from each other, from the Aral to the Black Sea inclusive, were formerly united in this vast pre-historical Mediterranean ; which (even if we restrict its limits to the boundaries we already know, and do not extend them eastward, amid low regions untrodden by geologists) must have exceeded in size the present Mediterranean! On the accompanying map, Murchison shows

6160-403: The others being the Red Sea , the White Sea and the Yellow Sea . 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

6248-454: The outflow of fresher Black Sea surface-water into the Sea of Marmara occurs near the surface. According to Gregg (2002), 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 m /s (390,000 cu ft/s) or around 350 km /a (84 cu mi/a). The following water budget can be estimated: The southern sill of

6336-507: 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

6424-488: The photic zone, enhancing productivity. In total, the Black Sea's biodiversity contains around one-third of the Mediterranean's and is experiencing natural and artificial invasions or "Mediterranizations". The main phytoplankton groups present in the Black Sea are dinoflagellates , diatoms , coccolithophores and cyanobacteria . Generally, the annual cycle of phytoplankton development comprises significant diatom and dinoflagellate-dominated spring production, followed by

6512-434: The present Caspian Sea , in which the univalves of freshwater origin are associated with forms of Cardiacae and Mytili that are common to partially saline or brackish waters. This distinctive fauna has been found throughout all the enormously developed Tertiary formations of the southern and south-eastern steppes. ... and leads at once to the conviction, that during long periods antecedent, as will be hereafter explained, to

6600-730: The preservation of ancient shipwrecks which have been found in the Black Sea, which 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

6688-651: The recital of travellers and from specimens of the rock, we have no doubt that it extended to Khivah and the Aral Sea ;; beyond which the low level of the adjacent eastern deserts would lead us to infer, that it spread over wide tracts in Asia now inhabited by the Turkomans and Kirghis , and was bounded only by the mountains of the Hindoo Kusk and Chinese Tartary . ... there can be no sort of doubt, that all

6776-493: The region. As a result of these characteristics the Black Sea has gained interest from the field of marine archaeology , as ancient shipwrecks in excellent states of preservation have been discovered, such as the Byzantine wreck Sinop D , located in the anoxic layer off the coast of Sinop, Turkey . Modelling shows that, in the event of an asteroid impact on the Black Sea, the release of hydrogen sulfide clouds would pose

6864-469: The sea are usually equivalents of the English name "Black Sea", including these given in the countries bordering the sea: 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: The Black Sea is one of four seas named in English after common color terms –

6952-647: 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

7040-419: The southern end of the Paleo-Tethys Ocean. A rift formed along the northern continental shelf of Southern Pangaea (Gondwana). Over the next 60 million years, that piece of shelf, known as Cimmeria , traveled north, pushing the floor of the Paleo-Tethys Ocean under the eastern end of northern Pangaea (early / proto- Laurasia ). The Neo-Tethys Ocean formed between Cimmeria and Gondwana, directly over where

7128-497: The southern shoreline before Greek colonisation due to its difficult navigation and hostile barbarian natives (7.3.6), and that the name was changed to "hospitable" after the Milesians colonised 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 colour symbolism representing

7216-835: The time around the Early Cretaceous ran very differently from the way they do today. Between the Jurassic and the Late Cretaceous , which started about 100 Mya, Gondwana began breaking up, pushing Africa and India north across the Tethys and opening up the Indian Ocean. Throughout the Cenozoic (66 million to the dawn of the Neogene, 23 Mya), the connections between the Atlantic and Indian Oceans across

7304-674: 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

7392-408: The two layers. Surface water leaves the Black Sea with a salinity of 17 practical salinity units (PSU) and reaches the Mediterranean with a salinity of 34 PSU. Likewise, an inflow of the Mediterranean with salinity 38.5 PSU experiences a decrease to about 34 PSU. Mean surface circulation is cyclonic ; waters around the perimeter of the Black Sea circulate in a basin-wide shelfbreak gyre known as

7480-458: 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,

7568-435: The world's great rivers, lakes and fountains. The eastern part of the Tethys Ocean is sometimes referred to as Eastern Tethys. The western part of the Tethys Ocean is called Tethys Sea, Western Tethys Ocean, or Paratethys or Alpine Tethys Ocean. The Black , Caspian , and Aral seas are thought to be its crustal remains, though the Black Sea may, in fact, be a remnant of the older Paleo-Tethys Ocean . The Western Tethys

7656-589: Was created. By the Late Triassic , all that was left of the Paleo-Tethys Ocean was a narrow seaway. In the Early Jurassic epoch, as part of the Alpine Orogeny , the oceanic crust of the Paleo-Tethys subducted under the Cimmerian plate, closing the ocean from west to east. A last remnant of Paleo-Tethys Ocean might be an oceanic crust under the Black Sea . ( Anatolia , to the sea's south,

7744-534: Was not simply a single open ocean. It covered many small plates, Cretaceous island arcs , and microcontinents . Many small oceanic basins ( Valais Ocean , Piemont-Liguria Ocean , Meliata Ocean ) were separated from each other by continental terranes on the Alboran , Iberian , and Apulian plates. The high sea level in the Mesozoic flooded most of these continental domains, forming shallow seas. During

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