How large is the Caspian Sea?
19653787#1
The wide and endorheic Caspian Sea has a north–south orientation and its main freshwater inflow, the Volga River, enters at the shallow north end. Two deep basins occupy its central and southern areas. These facts lead to horizontal differences in temperature, salinity, and ecology. The Caspian Sea spreads out over nearly 750 miles (1,200 km) from north to south, with an average width of 200 miles (320 km). It covers a region of around 149,200 square miles (386,400 square km)—bigger than the region of Japan—and its surface is about 90 feet (27 meters) below sea level. The sea bed in the southern part reaches as low as 1,023 m (3,356 ft) below sea level, which is the second lowest natural depression on earth after Lake Baikal (−1,180 m, −3,871 ft). The ancient inhabitants of its coast perceived the Caspian Sea as an ocean, probably because of its saltiness and large size.
Caspian Sea
19653787#13
The Caspian has characteristics common to both seas and lakes. It is often listed as the world's largest lake, although it is not a freshwater lake. It contains about 3.5 times more water, by volume, than all five of North America's Great Lakes combined. The Caspian was once part of the Tethys Ocean, but became landlocked about 5.5 million years ago due to plate tectonics. The Volga River (about 80% of 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.
Caspian Sea
19653787#22
Archeological studies of Gobustan petroglyphs indicate that there once had been dolphins and porpoises, or a certain species of beaked whales and a whaling scene indicates large baleen whales likely being present in Caspian Sea at least until when the Caspian Sea ceased being a part of the ocean system or until the Quaternary or much more recent periods such as until the last glacial period or antiquity. Although the rock art on Kichikdash Mountain is assumed to be of a dolphin or of a beaked whale, it might instead represent the famous beluga sturgeon due to its size (430 cm in length), but fossil records suggest certain ancestors of modern dolphins and whales, such as "Macrokentriodon morani" (bottlenose dolphins) and "Balaenoptera sibbaldina" (blue whales) were presumably larger than their present descendants. From the same artworks, auks, like Brunnich's Guillemot could also have been in the sea as well, and these petroglyphs suggest marine inflow between the current Caspian Sea and 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 Caspian/Black Seas regions.
Caspian Sea
3025441#3
The Caspian Depression is below sea-level, consisting of large areas of marshlands in the eastern region. It is one of the largest flat lowland areas in Central Asia, covering approximately . The area is very rich in underground oil and gas reserves, and oil and natural gas pipelines cross the depression from north to south and east to west. Many geologists believe the Caspian Sea and the depression were formed by tectonic forces. Some of them also believe that the North Caspian depression became separated from the open ocean in ancient times to form an enormous salt lake. Part of the ancient Silk Road ran through this region. The two largest cities in the depression are Astrakhan in Russia, and Atyrau in Kazakhstan. Today, the region is used mainly for livestock raising.
Caspian Depression
19653787#10
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 . The sea noticeably drops off towards the Middle Caspian, where the average depth is . The Southern Caspian is the deepest, with oceanic depths of over , 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 the winter, and in the coldest winters ice forms in the south as well.
Caspian Sea
49319487#0
The Black Sea-Caspian Steppe is an informal name for that part of the Eurasian Steppe that extends south between the Black and Caspian Seas. It is usually treated as part of the Pontic-Caspian steppe which includes the area north of the Black and Caspian Seas, but there is some reason to treat it as a distinct place. Its natural boundaries are the Sea of Azov and Black Sea on the west, the Caucasus Mountains on the south and the Caspian Sea on the east. Its northern boundary may be taken as the triangle formed by the lower Don River and Volga River which are about 60 km apart to the west of Volgograd. This article excludes the north slope of the Caucasus which is not steppe and has a distinct geography and history.
Black Sea–Caspian Steppe
19653787#0
The Caspian Sea is the world's largest inland body of water, variously classed as the world's largest lake or a full-fledged sea. It is an endorheic basin (a basin without outflows) located between Europe and Asia, to the east of the Caucasus Mountains and to the west of the broad steppe of Central Asia. It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaijan to the west, Iran to the south, and Turkmenistan to the southeast. The Caspian Sea is home to a wide range of species and may be best known for its caviar and oil industries. Pollution from the oil industry and dams on rivers draining into the Caspian Sea have had negative effects on the organisms living in the sea.
Caspian Sea
349764#7
The lower part of the river flows through the Kura-Aras Lowland, which covers most of central Azerbaijan and abuts the Caspian Sea. The Kura is the third largest, after the Volga and Ural, of the rivers that flow into the Caspian. Its delta is the fourth largest among the rivers that flow into the Caspian Sea, and is divided into three main sections, or "sleeves", composed of sediment the river deposited during different periods of time. Before 1998, the river flowed all the way to the tip of the delta, where it discharged into the Caspian. In that year, the river escaped its channel and started to flow off to the west, leaving the last few kilometers abandoned. The course change is believed to be the result of a rise in the level of the Caspian Sea coupled with a major flood of the Kura.
Kura (Caspian Sea)
19653787#8
The Caspian Sea, like the Black Sea, Namak Lake, and Lake Urmia, is a remnant of the ancient Paratethys Sea. It became landlocked about 5.5 million years ago due to tectonic uplift and a fall in sea level. 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 the basin. (Comparable evaporite beds underlie the Mediterranean.) Due to the current inflow of fresh water, the Caspian Sea is a freshwater lake in its northern portions, and 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 embayment, which dried up when water flow from 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.
Caspian Sea
19653787#9
The Caspian Sea is the largest inland body of water in the world and accounts for 40 to 44% of the total lacustrine waters of the world. The coastlines of the Caspian are shared by Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The Caspian 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 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.
Caspian Sea