- Caspian Depression
Caspian Depression ( _ru. Прикаспийская низменность, Caspian Lowland) is a low-lying
flatlandregion encompassing the northern part of the Caspian Sea, the largest enclosed body of wateron Earth. [cite web
title=Caspian Sea » General background
publisher=Caspian Environment Programme
accessdate=2006-12-31 ] . It is part of the wider
Aral-Caspian Depressionaround the Aral and Caspian seas.
The lowest point of the depression is 28m or 92 feet below sea level. The depression lies at the southern end of the
Ryn Desert, and is in both Kazakhstanand Russia. Most of the Russian Republic of Kalmykialies in the Caspian Depression. The Volga Riverand the Ural Riverflow into the Caspian Sea through this region. The deltas of the Ural and Volga Rivers are extensive wetlands.
The North Caspian depression is part of the
continentalor semi-ariddesert biome. The area receives 30 centimeters (12 in) of rain or less per year, on average, and less than 10% of the region is irrigated. Karagiye, the lowest point in Kazakhstan, is in the depression, at 132 meters (433 ft) below sea level.
Much of 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 200,000 kilometers² (77,220 miles²). 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 tectonicforces. 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 Roadran through this region. The two largest cities in the depression are Astrakhanin Russia, and Atyrauin Kazakhstan. Today, the region is used mainly for livestock raising.
The depression is also noted for
salt domes, particularly Volgograd salt, whose sizes increase dramatically as one travels from the Ryn Deserttoward the Caspian Sea. Russian satellite photos have revealed huge deposits of salt domes (about 1,200), in the Caspian Depression in western Kazakhstan. One dome, called the Chelkar Deposit, covers an area of 3,237 kilometers² (1,249 miles²) and is nearly 8 kilometers (4.9 miles) deep.
The southern region of the depression, or the north coast of the Caspian Sea, is characterized by large development of damp sites resulting from
tidalphenomena. The depression is also home to a large number of insect species, with several thousand different species likely living in the region around the Caspian Sea. Studies have shown that water pollution, mostly coming from the Volga River, poses a serious threat to the biodiversityof the Caspian Depression. Water pollution is contributed mainly by industrial, agricultural, and household discharges.
* Evaporites of North Border of North Caspian Depression - "Internet Geology News Letter No. 178", January 13, 2003.
* [http://www.spacetoday.org/Satellites/SatBytes/SaltDomes.html Space Today Online] .
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