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95-728: It is located in the eastern part of the Caspian Sea . Regular lines serve routes to Baku ( Azerbaijan ), Aktau ( Kazakhstan ) and Astrakhan ( Russia ). It is the largest seaport in Turkmenistan. The port was founded in October 1896 on the eastern coast of the Caspian Sea. On January 1, 1903, the Merchant marine port Authority was established. Cargo traffic increased over the years, therefore, an idea occurred to build

190-704: A cave in Georgia. Discoveries in the Hotu cave and the adjacent Kamarband cave , near the town of Behshahr , Mazandaran south of the Caspian in Iran, suggest human habitation of the area as early as 11,000 years ago. Ancient Greeks focused on the civilization on the south shore – they call it the (H)yr(c/k)anian Sea ( Ancient Greek : Υρκανία θάλαττα , with sources noting the latter word was evolving then to today's Thelessa : late Ancient Greek : θάλασσα ). Hafiz-i Abru ,

285-567: A fall in sea level . The Caspian Sea was a comparatively small endorheic lake during the Pliocene , but its surface area increased fivefold around the time of the Pliocene-Pleistocene transition. During warm and dry climatic periods, the landlocked sea almost dried up, depositing evaporitic sediments like halite that were covered by wind-blown deposits and were sealed off as an evaporite sink when cool, wet climates refilled

380-465: A ferry terminal. In 1959, the port began construction of a ferry. Regular voyages on the ferryline from Baku to Krasnovodsk started in 1962. The ferry terminal transportation has significantly accelerated cargo delivery. In 2000–2003, a massive reconstruction project began. The old port was reconstructed along with construction of new berths for ships and warehouses and other facilities with modern equipment. This made it possible to provide port services at

475-623: A fourteenth century Timurid Empire geographer, recorded that the destruction of the Oxus river dam and irrigation works diverted the river flow towards the Caspian Sea, which caused the Aral sea to nearly disappear. Later, in the Tang dynasty (618–907), the sea was the western limit of the Chinese Empire. The area is rich in fossil fuels . Oil wells were being dug in the region as early as

570-491: A globe-spanning mid-ocean ridge system, as well as undersea volcanoes , oceanic trenches , submarine canyons , oceanic plateaus and abyssal plains . The mass of the oceans is approximately 1.35 × 10   metric tons , or about 1/4400 of the total mass of the Earth. The oceans cover an area of 3.618 × 10  km with a mean depth of 3,682 m, resulting in an estimated volume of 1.332 × 10  km . Each region of

665-501: A rate anywhere from 1 mm to 1 cm every 1000 years. Hydrogenous sediments are uncommon. They only occur with changes in oceanic conditions such as temperature and pressure. Rarer still are cosmogenous sediments. Hydrogenous sediments are formed from dissolved chemicals that precipitate from the ocean water, or along the mid-ocean ridges, they can form by metallic elements binding onto rocks that have water of more than 300 °C circulating around them. When these elements mix with

760-488: A result of the petrochemical industry; this has significantly decreased the number of species of marine birds in the area. Existing and planned oil and gas pipelines under the sea further increase the potential threat to the environment. The high concentration of mud volcanoes under the Caspian Sea were thought to be the cause of a fire that broke out 75 kilometers from Baku on July 5, 2021. The State oil company of Azerbaijan SOCAR said preliminary information indicated it

855-402: Is absorbed before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain ; most organisms in the benthic zone are scavengers or detritivores . Seabed topography ( ocean topography or marine topography ) refers to

950-434: Is a vertical coordinate used in geology, paleontology , oceanography , and petrology (see ocean drilling ). The acronym "mbsf" (meaning "meters below the seafloor") is a common convention used for depths below the seafloor. Sediments in the seabed vary in origin, from eroded land materials carried into the ocean by rivers or wind flow, waste and decompositions of sea creatures, and precipitation of chemicals within

1045-518: Is a "sea gate", linking Central Asia to Europe by sea, road and rail routes and serves as a major transit hub in the region. The port of Turkmenbashi has a connection with the ports of the following cities: Since 2020 the Turkmenbashi International Seaport appears on the obverse of the 1 banknote of Turkmen_manat . Caspian Sea The Caspian Sea is the world's largest inland body of water , described as

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1140-484: Is a wholly freshwater species. The zebra mussel is native to the Caspian and Black Sea basins, but has become an invasive species elsewhere, when introduced. The area has given its name to several species, including the Caspian gull and the Caspian tern . The Caspian seal ( Pusa caspica ) is the only aquatic mammal endemic to the Caspian Sea, being one of very few seal species that live in inland waters, but it

1235-477: Is abundant in the deep sea around hydrothermal vents . Large deep sea communities of marine life have been discovered around black and white smokers – vents emitting chemicals toxic to humans and most vertebrates . This marine life receives its energy both from the extreme temperature difference (typically a drop of 150 degrees) and from chemosynthesis by bacteria . Brine pools are another seabed feature, usually connected to cold seeps . In shallow areas,

1330-590: Is controversial. Environmental advocacy groups such as Greenpeace and the Deep Sea Mining Campaign claimed that seabed mining has the potential to damage deep sea ecosystems and spread pollution from heavy metal-laden plumes. Critics have called for moratoria or permanent bans. Opposition campaigns enlisted the support of some industry figures, including firms reliant on the target metals. Individual countries with significant deposits within their exclusive economic zones (EEZ's) are exploring

1425-405: Is different from those inhabiting freshwaters due to the hydrological environment of the sea. A century ago the Caspian was home to more than one million seals . Today, fewer than 10% remain. Archeological studies of Gobustan Rock Art have identified what may be oceanic species including cetaceans from baleen whales to dolphins , and auks most likely Brunnich's Guillemot , although

1520-447: Is divided into layers or zones, each with typical features of salinity, pressure, temperature and marine life , according to their depth. Lying along the top of the abyssal plain is the abyssal zone , whose lower boundary lies at about 6,000 m (20,000 ft). The hadal zone – which includes the oceanic trenches, lies between 6,000 and 11,000 metres (20,000–36,000 ft) and is the deepest oceanic zone. Depth below seafloor

1615-675: Is divided into three distinct physical regions: the Northern, Middle, and Southern Caspian. The Northern–Middle boundary is the Mangyshlak Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle–Southern boundary is the Apsheron Threshold , a sill of tectonic origin between the Eurasian continent and an oceanic remnant, that runs through Zhiloi Island and Cape Kuuli. The Garabogazköl Bay

1710-461: Is estimated that the global ocean floor holds more than 120 million tons of cobalt, five times the amount found in terrestrial reserves. As of July 2024 , only exploratory licenses have been issued, with no commercial-scale deep sea mining operations yet. The International Seabed Authority (ISA) regulates all mineral-related activities in international waters and has granted 31 exploration licenses so far: 19 for polymetallic nodules, mostly in

1805-414: Is not moving so quickly. This means that larger grains of sediment may come together in higher energy conditions and smaller grains in lower energy conditions. Benthos (from Ancient Greek βένθος ( bénthos )  'the depths [of the sea]'), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river , lake , or stream , also known as

1900-551: Is predicted that during the 21st century, the depth of the sea will decrease by 9–18 m (30–60 ft) due to global warming and the process of desertification , leading to an ecocide . The sea's name stems from Caspi , the ancient people who lived to the southwest of the sea in Transcaucasia . Strabo (died circa AD 24) wrote that "to the country of the Albanians ( Caucasian Albania , not to be confused with

1995-480: Is the next most abundant material on the seafloor. Biogenous sediments are biologically produced by living creatures. Sediments made up of at least 30% biogenous material are called "oozes." There are two types of oozes: Calcareous oozes and Siliceous oozes. Plankton grow in ocean waters and create the materials that become oozes on the seabed. Calcareous oozes are predominantly composed of calcium shells found in phytoplankton such as coccolithophores and zooplankton like

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2090-453: Is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to the isthmus that cuts it off from the Caspian. Differences between the three regions are dramatic. The Northern Caspian only includes the Caspian shelf, and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only 5–6 m (16–20 ft). The sea noticeably drops off towards

2185-561: Is through their descriptive classification. These sediments vary in size, anywhere from 1/4096 of a mm to greater than 256 mm. The different types are: boulder, cobble, pebble, granule, sand, silt, and clay, each type becoming finer in grain. The grain size indicates the type of sediment and the environment in which it was created. Larger grains sink faster and can only be pushed by rapid flowing water (high energy environment) whereas small grains sink very slowly and can be suspended by slight water movement, accumulating in conditions where water

2280-570: The Khazar sea : Turkmen : Hazar deňzi ; Azerbaijani : Xəzər dənizi , Turkish : Hazar Denizi . In all these the first word refers to the historical Khazar Khaganate , a large empire based to the north of the Caspian Sea between the 7th and 10th centuries. In Iran, the lake is referred to as the Mazandaran Sea ( Persian : دریای مازندران ), after the historic Mazandaran Province at its southern shores. Old Russian sources use

2375-683: The Azerbaijan Academy of Sciences estimated that the level of the sea was dropping by more than six centimetres per year due to increased evaporation due to rising temperatures caused by climate change . The Volga River , the longest river in Europe, drains 20% of the European land area and is the source of 80% of the Caspian's inflow. Heavy development in its lower reaches has caused numerous unregulated releases of chemical and biological pollutants. The UN Environment Programme warns that

2470-711: The Black Sea . In the late Pontian stage , a mountain arch rose across the south basin and divided it into the Khachmaz and Lankaran Lakes (or early Balaxani ). The period of restriction to the south basin was reversed during the Akchagylian – the lake became more than three times its size today and took again the first of a series of contacts with the Black Sea and Aral Sea . A recession of Lake Akchagyl completed stage one. The earliest hominid remains found around

2565-630: The Khvalyn or Khvalis Sea ( Хвалынское море / Хвалисское море ) after the name of Khwarezmia . Among Greeks and Persians in classical antiquity it was the Hyrcanian ocean. Renaissance European maps labelled it as the Abbacuch Sea (Oronce Fine's 1531 world map), Mar de Bachu (Ortellius' 1570 map), or Mar de Sala (the Mercator 1569 world map ). It was also sometimes called

2660-725: The Uzboy River , as did the Syr Darya farther north. The Caspian has several small islands, primarily located in the north with a collective land area of roughly 2,000 km (770 sq mi). Adjacent to the North Caspian is the Caspian Depression , a low-lying region 27 m (89 ft) below sea level . The Central Asian steppes stretch across the northeast coast, while the Caucasus mountains hug

2755-484: The Volga , enters at the shallow north end. Two deep basins form its central and southern zones. These lead to horizontal differences in temperature, salinity, and ecology. The seabed in the south reaches 1,023 m (3,356 ft) below sea level, which is the third-lowest natural non-oceanic depression on Earth after Baikal and Tanganyika lakes. Written accounts from the ancient inhabitants of its coast perceived

2850-437: The abyssal plain regions of the ocean are relatively flat and covered in many layers of sediments. Sediments in these flat areas come from various sources, including but not limited to: land erosion sediments from rivers, chemically precipitated sediments from hydrothermal vents, Microorganism activity, sea currents eroding the seabed and transporting sediments to the deeper ocean, and phytoplankton shell materials. Where

2945-453: The benthic zone . This community lives in or near marine or freshwater sedimentary environments , from tidal pools along the foreshore , out to the continental shelf , and then down to the abyssal depths . Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column . The pressure difference can be very significant (approximately one atmosphere for every 10 metres of water depth). Because light

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3040-425: The continental rise , slope , and shelf . The depth within the seabed itself, such as the depth down through a sediment core , is known as the "depth below seafloor". The ecological environment of the seabed and the deepest waters are collectively known, as a habitat for creatures, as the " benthos ". Most of the seabed throughout the world's oceans is covered in layers of marine sediments . Categorized by where

3135-553: The tidal areas of the Volga delta and riparian forests of the Samur River delta. The shoreline is also a unique refuge for plants adapted to the loose sands of the Central Asian Deserts . The principal limiting factors to successful establishment of plant species are hydrological imbalances within the surrounding deltas, water pollution , and various land reclamation activities. The water level change within

3230-401: The twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it the second leading producer of oil and natural gas globally. Caspian littoral states join efforts to develop infrastructure, tourism and trade in the region. The first Caspian Economic Forum

3325-470: The world's largest lake and usually referred to as a full-fledged sea . An endorheic basin , it lies between Europe and Asia : east of the Caucasus , west of the broad steppe of Central Asia , south of the fertile plains of Southern Russia in Eastern Europe , and north of the mountainous Iranian Plateau . It covers a surface area of 371,000 km (143,000 sq mi) (excluding

3420-411: The 10th century to reach oil "for use in everyday life, both for medicinal purposes and for heating and lighting in homes". By the 16th century, Europeans were aware of the rich oil and gas deposits locally. English traders Thomas Bannister and Jeffrey Duckett described the area around Baku as "a strange thing to behold, for there issueth out of the ground a marvelous quantity of oil, which serveth all

3515-433: The Black Sea basin or widespread Palearctic species such as crucian carp , Prussian carp , common carp , common bream , common bleak , asp , white bream , sunbleak , common dace , common roach , common rudd , European chub , sichel , tench , European weatherfish , wels catfish , northern pike , burbot , European perch and zander . Almost 30 non-indigenous, introduced fish species have been reported from

3610-809: The CCZ; 7 for polymetallic sulphides in mid-ocean ridges ; and 5 for cobalt-rich crusts in the Western Pacific Ocean . There is a push for deep sea mining to commence by 2025, when regulations by the ISA are expected to be completed. Deep sea mining is also possible in the exclusive economic zone (EEZ) of countries, such as Norway , where it has been approved. In 2022, the Cook Islands Seabed Minerals Authority (SBMA) granted three exploration licenses for cobalt-rich polymetallic nodules within their EEZ. Papua New Guinea

3705-515: The Caspian "suffers from an enormous burden of pollution from oil extraction and refining, offshore oil fields, radioactive wastes from nuclear power plants and huge volumes of untreated sewage and industrial waste introduced mainly by the Volga River". The magnitude of fossil fuel extraction and transport activity in the Caspian also poses a risk to the environment. The island of Vulf off Baku , for example, has suffered ecological damage as

3800-546: The Caspian Sea are from Dmanisi dating back to around 1.8 Ma and yielded a number of skeletal remains of Homo erectus or Homo ergaster . More later evidence for human occupation of the region came from a number of caves in Georgia and Azerbaijan such as Kudaro and Azykh Caves . There is evidence for Lower Palaeolithic human occupation south of the Caspian from western Alburz. These are Ganj Par and Darband Cave sites. Neanderthal remains also have been discovered at

3895-470: The Caspian Sea as an ocean, probably because of its salinity and large size. With a surface area of 371,000 square kilometres (143,000 sq mi), the Caspian Sea is nearly five times as big as Lake Superior (82,000 square kilometres (32,000 sq mi)). The Caspian Sea is home to a wide range of species and is famous for its caviar and oil industries. Pollution from the oil industry and dams on rivers that drain into it have harmed its ecology. It

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3990-725: The Caspian Sea is an indirect reason for which plants may not get established. These affect aquatic plants of the Volga Delta, such as Aldrovanda vesiculosa and the native Nelumbo caspica . About 11 plant species are found in the Samur River delta, including the unique liana forests that date back to the Tertiary period . Since 2019 UNESCO has admitted the lush Hyrcanian forests of Mazandaran , Iran as World Heritage Site under category (ix). The Caspian turtle ( Mauremys caspica ), although found in neighboring areas,

4085-488: The Caspian Sea, but only a few have become established. Six sturgeon species, the Russian , bastard , Persian , sterlet , starry and beluga , are native to the Caspian Sea. The last of these is arguably the largest freshwater fish in the world . The sturgeon yield roe (eggs) that are processed into caviar . Overfishing has depleted a number of the historic fisheries. In recent years, overfishing has threatened

4180-431: The Caspian region economies are highly dependent on this type of mineral wealth. The world energy markets were influenced by Azerbaijan and Kazakhstan, as they became strategically crucial in this sphere, thus attracting the largest share of foreign direct investment (FDI). All of the countries are rich in solar energy and harnessing potential, with the highest rainfall much less than the mountains of central Europe in

4275-641: The Kumyk Sea and Tarki Sea (derived from the name of the Kumyks and their historical capital Tarki ). The Caspian Sea is at its South Caspian Basin , like the Black Sea , a remnant of the ancient Paratethys Sea . Its seafloor is, therefore, a standard oceanic basalt and not a continental granite body. It is estimated to be about 30 million years old, and became landlocked in the Late Miocene , about 5.5 million years ago, due to tectonic uplift and

4370-531: The Middle Caspian, where the average depth is 190 m (620 ft). The Southern Caspian is the deepest, with oceanic depths of over 1,000 m (3,300 ft), greatly exceeding the depth of other regional seas, such as the Persian Gulf . The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively. The northern portion of the Caspian Sea typically freezes in

4465-529: The Protection of the Caspian Sea against Pollution from Land-based Sources in order to ensure better protection for the biodiversity of the Caspian Sea. The rising level of the Caspian Sea between 1995 and 1996 reduced the number of habitats for rare species of aquatic vegetation. This has been attributed to a general lack of seeding material in newly formed coastal lagoons and water bodies. Many rare and endemic plant species of Russia are associated with

4560-641: The amount of North Atlantic depressions that reach the interior, and they in turn are affected by cycles of the North Atlantic oscillation . Thus levels in the Caspian Sea relate to atmospheric conditions in the North Atlantic, thousands of kilometres to the northwest. The last short-term sea-level cycle started with a sea-level fall of 3 m (10 ft) from 1929 to 1977, followed by a rise of 3 m (10 ft) from 1977 until 1995. Since then smaller oscillations have taken place. A study by

4655-536: The amount of plastic thought – per Jambeck et al., 2015 – to currently enter the oceans annually. Deep sea mining is the extraction of minerals from the seabed of the deep sea . The main ores of commercial interest are polymetallic nodules , which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain . The Clarion–Clipperton zone (CCZ) alone contains over 21 billion metric tons of these nodules, with minerals such as copper , nickel , and cobalt making up 2.5% of their weight. It

4750-485: The balance between sedimentary processes and hydrodynamics however, anthropogenic influences can impact the natural system more than any physical driver. Marine topographies include coastal and oceanic landforms ranging from coastal estuaries and shorelines to continental shelves and coral reefs . Further out in the open ocean, they include underwater and deep sea features such as ocean rises and seamounts . The submerged surface has mountainous features, including

4845-584: The basin. (Comparable evaporite beds underlie the Mediterranean .) Due to the current inflow of fresh water in the north, the Caspian Sea water is almost fresh in its northern portions, getting more brackish toward the south. It is most saline on the Iranian shore, where the catchment basin contributes little flow. Currently, the mean salinity of the Caspian is one third that of Earth's oceans. The Garabogazköl lagoon , which dried up when water flow from

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4940-559: The coasts, but none in the deeper parts of the sea. Ogurja Ada is the largest island. The island is 37 km (23 mi) long, with gazelles roaming freely on it. In the North Caspian, the majority of the islands are small and uninhabited, like the Tyuleniy Archipelago , an Important Bird Area (IBA). The climate of the Caspian Sea is variable, with the cold desert climate (BWk), cold semi-arid climate (BSk), and humid continental climate (Dsa, Dfa) being present in

5035-450: The cold sea water they precipitate from the cooling water. Known as manganese nodules , they are composed of layers of different metals like manganese, iron, nickel, cobalt, and copper, and they are always found on the surface of the ocean floor. Cosmogenous sediments are the remains of space debris such as comets and asteroids, made up of silicates and various metals that have impacted the Earth. Another way that sediments are described

5130-465: The continental slope and the abyssal plain usually has a more gradual descent, and is called the continental rise , which is caused by sediment cascading down the continental slope. The mid-ocean ridge , as its name implies, is a mountainous rise through the middle of all the oceans, between the continents. Typically a rift runs along the edge of this ridge. Along tectonic plate edges there are typically oceanic trenches – deep valleys, created by

5225-480: The country of Albania ) belongs also the territory called Caspiane, which was named after the Caspian tribe, as was also the sea; but the tribe has now disappeared". Moreover, the Caspian Gates , part of Iran 's Tehran province , may evince such people migrated to the south. The Iranian city of Qazvin shares the root of its name with this common name for the sea. The traditional and medieval Arabic name for

5320-475: The country to burn in their houses. This oil is black and is called nefte . There is also by the town of Baku, another kind of oil which is white and very precious [i.e., petroleum ]." Today, oil and gas platforms abound along the edges of the sea. During the rule of Peter I the Great , Fedor I. Soimonov was a pioneering explorer of the sea. He was a hydrographer who charted and greatly expanded knowledge of

5415-486: The current Caspian Sea and either the Arctic Ocean or North Sea , or the Black Sea . This is supported by the existences of current endemic, oceanic species such as lagoon cockles which was genetically identified to originate in the Caspian and Black Seas regions. The sea's basin (including associated waters such as rivers) has 160 native species and subspecies of fish in more than 60 genera . About 62% of

5510-586: The fish stocks, since it targets reproductive females. Reptiles native to the region include the spur-thighed tortoise ( Testudo graeca buxtoni ) and Horsfield's tortoise . The main geologic history locally had two stages. The first is the Miocene , determined by tectonic events that correlate with the closing of the Tethys Sea . The second is the Pleistocene noted for its glaciation cycles and

5605-416: The foraminiferans. These calcareous oozes are never found deeper than about 4,000 to 5,000 meters because at further depths the calcium dissolves. Similarly, Siliceous oozes are dominated by the siliceous shells of phytoplankton like diatoms and zooplankton such as radiolarians. Depending on the productivity of these planktonic organisms, the shell material that collects when these organisms die may build up at

5700-656: The full run of the present Volga. During the first stage, the Tethys Sea had evolved into the Sarmatian Lake, that was created from the modern Black Sea and south Caspian, when the collision of the Arabian peninsula with West Asia pushed up the Kopet Dag and Caucasus Mountains , lasting south and west limits to the basin. This orogenic movement was continuous, while the Caspian was regularly disconnected from

5795-445: The highest level. In 2013, the port built passenger catamaran "Charlak". It was the first shipbuilding project of this level in the history of the port. On August 15, 2013 the construction of a new port began. It cost $ 2 billion and was built by Turkish company GAP İnşaat . At the groundbreaking ceremony was attended by President of Turkmenistan Gurbanguly Berdimuhamedov and Turkish Prime Minister Recep Tayyip Erdoğan . Construction

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5890-418: The highly saline lagoon of Garabogazköl to its east), an area approximately equal to that of Japan , with a volume of 78,200 km (19,000 cu mi). It has a salinity of approximately 1.2% (12 g/L), about a third of the salinity of average seawater . It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the southwest, Iran to the south, and Turkmenistan to

5985-487: The inflow) and the Ural River discharge into the Caspian Sea, but it has no natural outflow other than by evaporation . Thus the Caspian ecosystem is a closed basin , with its own sea level history that is independent of the eustatic level of the world's oceans. The sea level of the Caspian has fallen and risen, often rapidly, many times over the centuries. Some Russian historians, such as Lev Gumilev , claim that

6080-440: The main body of the Caspian was blocked in the 1980s but has since been restored, routinely exceeds oceanic salinity by a factor of 10. The Caspian Sea is the largest inland body of water in the world by area and accounts for 40–44% of the total lake waters of the world, and covers an area larger than Germany . The coastlines of the Caspian are shared by Azerbaijan , Iran , Kazakhstan , Russia , and Turkmenistan . The Caspian

6175-444: The mantle circulation movement from the mid-ocean mountain ridge to the oceanic trench. Hotspot volcanic island ridges are created by volcanic activity, erupting periodically, as the tectonic plates pass over a hotspot. In areas with volcanic activity and in the oceanic trenches there are hydrothermal vents – releasing high pressure and extremely hot water and chemicals into the typically freezing water around it. Deep ocean water

6270-415: The materials come from or composition, these sediments are classified as either: from land ( terrigenous ), from biological organisms (biogenous), from chemical reactions (hydrogenous), and from space (cosmogenous). Categorized by size, these sediments range from very small particles called clays and silts , known as mud, to larger particles from sand to boulders . Features of the seabed are governed by

6365-453: The mountains of the west, which are also rich in hydroelectricity sources. Iran has high fossil fuel energy potential. It has reserves of 137.5 billion barrels of crude oil , the fourth largest in the world, producing around four million barrels a day. Iran has an estimated 988.4 trillion cubic feet of natural gas , around 16 percent of world reserves, thus key to current paradigms in global energy security. Russia's economy ranks as

6460-524: The northern portions of the Caspian Sea, while the Mediterranean climate (Csa) and humid subtropical climate (Cfa) are present in the southern portions of the Caspian Sea. The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not freshwater : the 1.2% salinity classes it with brackish water bodies. It contains about 3.5 times as much water, by volume, as all five of North America's Great Lakes combined. The Volga River (about 80% of

6555-448: The oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources. The structure of the oceans, starting with the continents, begins usually with a continental shelf , continues to the continental slope – which is a steep descent into the ocean, until reaching the abyssal plain – a topographic plain , the beginning of the seabed, and its main area. The border between

6650-441: The physics of sediment transport and by the biology of the creatures living in the seabed and in the ocean waters above. Physically, seabed sediments often come from the erosion of material on land and from other rarer sources, such as volcanic ash . Sea currents transport sediments, especially in shallow waters where tidal energy and wave energy cause resuspension of seabed sediments. Biologically, microorganisms living within

6745-518: The rising of the Caspian in the 10th century caused the coastal towns of Khazaria to flood, resulting in the Khazars losing approximately two-thirds of their territory due to flooding. Over the centuries, Caspian Sea levels have changed in synchrony with the estimated discharge of the Volga, which in turn depends on rainfall levels in its vast catchment basin. Precipitation is related to variations in

6840-470: The rock art on Kichikdash Mountain which is assumed to depict either a beaked whale or a dolphin , it may represent the famous beluga sturgeon instead due to its size (430 cm in length). These petroglyphs may suggest potential presences of oceanic faunas in the Caspian Sea presumably until the Quaternary or even the last glacial period or antiquity due to historic marine inflow between

6935-746: The sea was Baḥr ('sea') Khazar , but in recent centuries the common and standard name in Arabic language has become بحر قزوين Baḥr Qazvin , the Arabized form of Caspian. In modern Russian language, it is known as Russian : Каспи́йское мо́ре , Kaspiyskoye more . Some Turkic ethnic groups refer to it with the Caspi(an) descriptor; in Kazakh it is called Каспий теңізі , Kaspiy teñizi , Kyrgyz : Каспий деңизи , romanized :  Kaspiy deñizi , Uzbek : Kaspiy dengizi . Others refer to it as

7030-537: The sea water itself, including some from outer space. There are four basic types of sediment of the sea floor: Terrigenous sediment is the most abundant sediment found on the seafloor. Terrigenous sediments come from the continents. These materials are eroded from continents and transported by wind and water to the ocean. Fluvial sediments are transported from land by rivers and glaciers, such as clay, silt, mud, and glacial flour. Aeolian sediments are transported by wind, such as dust and volcanic ash. Biogenous sediment

7125-496: The sea. He drew a set of four maps and wrote Pilot of the Caspian Sea , the first lengthy report and modern maps. These were published in 1720 by the Russian Academy of Sciences . Countries in the Caspian region, particularly Azerbaijan , Kazakhstan and Turkmenistan , have high-value natural-resource-based economies, where the oil and gas compose more than 10 percent of their GDP and 40 percent of their exports. All

7220-488: The seabed , and these satellite-derived maps are used extensively in the study and exploration of the ocean floor. In 2020 scientists created what may be the first scientific estimate of how much microplastic currently resides in Earth's seafloor , after investigating six areas of ~3 km depth ~300 km off the Australian coast. They found the highly variable microplastic counts to be proportionate to plastic on

7315-440: The seabed can host sediments created by marine life such as corals, fish, algae, crabs, marine plants and other organisms. The seabed has been explored by submersibles such as Alvin and, to some extent, scuba divers with special equipment. Hydrothermal vents were discovered in 1977 by researchers using an underwater camera platform. In recent years satellite measurements of ocean surface topography show very clear maps of

7410-404: The seabed has typical features such as common sediment composition, typical topography, salinity of water layers above it, marine life, magnetic direction of rocks, and sedimentation . Some features of the seabed include flat abyssal plains , mid-ocean ridges , deep trenches , and hydrothermal vents . Seabed topography is flat where layers of sediments cover the tectonic features. For example,

7505-425: The seabed of the global ocean is governed by plate tectonics . Most of the ocean is very deep, where the seabed is known as the abyssal plain . Seafloor spreading creates mid-ocean ridges along the center line of major ocean basins, where the seabed is slightly shallower than the surrounding abyssal plain. From the abyssal plain, the seabed slopes upward toward the continents and becomes, in order from deep to shallow,

7600-501: The seabed sediments change seabed chemistry. Marine organisms create sediments, both within the seabed and in the water above. For example, phytoplankton with silicate or calcium carbonate shells grow in abundance in the upper ocean, and when they die, their shells sink to the seafloor to become seabed sediments. Human impacts on the seabed are diverse. Examples of human effects on the seabed include exploration, plastic pollution, and exploitation by mining and dredging operations. To map

7695-592: The seabed, ships use acoustic technology to map water depths throughout the world. Submersible vehicles help researchers study unique seabed ecosystems such as hydrothermal vents . Plastic pollution is a global phenomenon, and because the ocean is the ultimate destination for global waterways, much of the world's plastic ends up in the ocean and some sinks to the seabed. Exploitation of the seabed involves extracting valuable minerals from sulfide deposits via deep sea mining, as well as dredging sand from shallow environments for construction and beach nourishment . Most of

7790-411: The seafloor is actively spreading and sedimentation is relatively light, such as in the northern and eastern Atlantic Ocean , the original tectonic activity can be clearly seen as straight line "cracks" or "vents" thousands of kilometers long. These underwater mountain ranges are known as mid-ocean ridges . Other seabed environments include hydrothermal vents, cold seeps, and shallow areas. Marine life

7885-410: The shape of the land ( topography ) when it interfaces with the ocean. These shapes are obvious along coastlines, but they occur also in significant ways underwater. The effectiveness of marine habitats is partially defined by these shapes, including the way they interact with and shape ocean currents , and the way sunlight diminishes when these landforms occupy increasing depths. Tidal networks depend on

7980-403: The southeast. The name of the Caspian sea is derived from the ancient Iranic Caspi people. The sea stretches 1,200 km (750 mi) from north to south, with an average width of 320 km (200 mi). Its gross coverage is 386,400 km (149,200 sq mi) and the surface is about 27 m (89 ft) below sea level . Its main freshwater inflow , Europe's longest river,

8075-905: The species and subspecies are endemic , as are 4–6 genera (depending on taxonomic treatment). The lake proper has 115 natives, including 73 endemics (63.5%). Among the more than 50 genera in the lake proper, 3–4 are endemic: Anatirostrum , Caspiomyzon , Chasar (often included in Ponticola ) and Hyrcanogobius . By far the most numerous families in the lake proper are gobies (35 species and subspecies), cyprinids (32) and clupeids (22). Two particularly rich genera are Alosa with 18 endemic species/subspecies and Benthophilus with 16 endemic species. Other examples of endemics are four species of Clupeonella , Gobio volgensis , two Rutilus , three Sabanejewia , Stenodus leucichthys , two Salmo , two Mesogobius and three Neogobius . Most non-endemic natives are either shared with

8170-421: The sturgeon population to the point that environmentalists advocate banning sturgeon fishing completely until the population recovers. The high price of sturgeon caviar – more than 1,500 Azerbaijani manats (US$ 880 as of April 2019 ) per kilo – allows fishermen to afford bribes to ensure the authorities look the other way, making regulations in many locations ineffective. Caviar harvesting further endangers

8265-474: The subject. Some children's play songs include elements such as "There's a hole at the bottom of the sea", or "A sailor went to sea... but all that he could see was the bottom of the deep blue sea". On and under the seabed are archaeological sites of historic interest, such as shipwrecks and sunken towns. This underwater cultural heritage is protected by the UNESCO Convention on the Protection of

8360-412: The surface and the angle of the seafloor slope. By averaging the microplastic mass per cm , they estimated that Earth's seafloor contains ~14 million tons of microplastic – about double the amount they estimated based on data from earlier studies – despite calling both estimates "conservative" as coastal areas are known to contain much more microplastic pollution . These estimates are about one to two times

8455-403: The water column. Related technologies include robotic mining machines, as surface ships, and offshore and onshore metal refineries. Wind farms, solar energy, electric vehicles , and battery technologies use many of the deep-sea metals. Electric vehicle batteries are the main driver of the critical metals demand that incentivizes deep sea mining. The environmental impact of deep sea mining

8550-402: The western shore. The biomes to both the north and east are characterized by cold, continental deserts. Conversely, the climate to the southwest and south are generally warm with uneven elevation due to a mix of highlands and mountain ranges ; the drastic changes in climate alongside the Caspian have led to a great deal of biodiversity in the region. The Caspian Sea has numerous islands near

8645-581: The winter, and in the coldest winters ice forms in the south as well. Over 130 rivers provide inflow to the Caspian, the Volga River being the largest. A second affluent, the Ural River , flows in from the north, and the Kura River from the west. In the past, the Amu Darya (Oxus) of Central Asia in the east often changed course to empty into the Caspian through a now-desiccated riverbed called

8740-458: Was a mud volcano which spewed both mud and flammable gas. It is calculated that during the 21st century, the water level of the Caspian Sea will decrease by 9–18 m (30–60 ft) due to the acceleration of evaporation due to global warming and the process of desertification , causing an ecocide . On October 23, 2021, Kazakhstan President Kassym-Jomart Tokayev signed the Protocol for

8835-480: Was completed in 2018. The project involves the construction of the ferry, passenger and cargo terminals in 1 mln 200 thousand square meters. It is also planned to build a shipyard. The port has great geopolitical importance in Eurasia. Being on the trade route Europe-Caucasus-Asia ( TRACECA ), it is able to accommodate vessels throughout the year, around the clock to carry out loading and unloading operations. The port

8930-421: Was convened on August 12, 2019, in Turkmenistan and brought together representatives of Kazakhstan, Russia, Azerbaijan, Iran and that state. It hosted several meetings of their ministers of economy and transport. Seabed The seabed (also known as the seafloor , sea floor , ocean floor , and ocean bottom ) is the bottom of the ocean . All floors of the ocean are known as 'seabeds'. The structure of

9025-516: Was the first country to approve a deep sea mining permit for the Solwara 1 project, despite three independent reviews highlighting significant gaps and flaws in the environmental impact statement. The most common commercial model of deep sea mining proposed involves a caterpillar-track hydraulic collector and a riser lift system bringing the harvested ore to a production support vessel with dynamic positioning , and then depositing extra discharge down

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