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Lake Baikal (; , (モンゴル語:Байгал нуур), ''Baygal nuur'', etymologically meaning, in Turkic, "the rich lake"〔Dervla Murphy (2007) ''Silverland: A Winter Journey Beyond the Urals'', London, John Murray, page 173〕) is a rift lake in Russia, located in southern Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast. Lake Baikal is the largest (by volume) freshwater lake in the world, containing roughly 20% of the world's unfrozen surface fresh water.〔 With a maximum depth of ,〔 Baikal is the world's deepest lake.〔(【引用サイトリンク】title=Deepest Lake in the World )〕 It is considered among the world's clearest lakes and is considered the world's oldest lake〔(Fact Sheet: Lake Baikal — A Touchstone for Global Change and Rift Studies ), July 1993 (accessed 4 December 2007)〕 — at 25 million years.〔(【引用サイトリンク】title=Lake Baikal – UNESCO World Heritage Centre )〕 It is the seventh-largest lake in the world by surface area. With of fresh water,〔 it contains more water than all the North American Great Lakes combined. Like Lake Tanganyika, Lake Baikal was formed as an ancient rift valley, having the typical long crescent shape with a surface area of . Baikal is home to more than 1,700 species of plants and animals, two-thirds of which can be found nowhere else in the world. The lake was declared a UNESCO World Heritage Site in 1996.〔(【引用サイトリンク】title=Lake Baikal — World Heritage Site )〕 It is also home to Buryat tribes who reside on the eastern side of Lake Baikal, rearing goats, camels, cattle, and sheep,〔 where the mean temperature varies from a winter minimum of to a summer maximum of . ==Geography and hydrography== Lake Baikal is in a rift valley, created by the Baikal Rift Zone, where the Earth's crust is slowly pulling apart.〔(【引用サイトリンク】title=The Oddities of Lake Baikal )〕 At long and wide, Lake Baikal has the largest surface area of any freshwater lake in Asia, at , and is the deepest lake in the world at . The bottom of the lake is below sea level, but below this lies some of sediment, placing the rift floor some below the surface: the deepest continental rift on Earth.〔 In geological terms, the rift is young and active—it widens about 2 cm (0.79 in) per year. The fault zone is also seismically active; hot springs occur in the area and notable earthquakes happen every few years. The lake is divided into three basins: North, Central, and South, with depths about , , and , respectively. Fault-controlled accommodation zones rising to depths about separate the basins. The North and Central basins are separated by Academician Ridge, while the area around the Selenga Delta and the Buguldeika Saddle separates the Central and South basins. The lake drains into the Angara tributary of the Yenisei. Notable landforms include Cape Ryty on Baikal's northwest coast. Baikal's age is estimated at 25–30 million years, making it one of the most ancient lakes in geological history. It is unique among large, high-latitude lakes, in that its sediments have not been scoured by overriding continental ice sheets. Russian, U.S., and Japanese cooperative studies of deep-drilling core sediments in the 1990s provide a detailed record of climatic variation over the past 6.7 million years.〔Kravchinsky, V.A., M.A. Krainov, M.E. Evans, J.A. Peck, J.W. King, M.I. Kuzmin, H. Sakai, T. Kawai, and D. Williams. Magnetic record of Lake Baikal sediments: chronological and paleoclimatic implication for the last 6.7 Ma. Palaeogeography, Palaeoclimatology, Palaeoecology, 195, 281-298, 2003.〕〔Kravchinsky, V.A., M.E. Evans, J.A. Peck, H. Sakai, M.A. Krainov, J.W. King, M.I. Kuzmin. A 640kyr geomagnetic and paleoclimatic record from Lake Baikal sediments. Geophysical Journal International, 170 (1), 101–116, doi:10.1111/j.1365-246X.2007.03411.x, 2007.〕 Longer and deeper sediment cores are expected in the near future. Lake Baikal is the only confined freshwater lake in which direct and indirect evidence of gas hydrates exists.〔M.I. Kuzmin ''et al.'' (1998). First find of gas hydrates in sediments of Lake Baikal. Doklady Adademii Nauk, 362: 541–543 (in Russian).〕 The lake is completely surrounded by mountains. The Baikal Mountains on the north shore and the taiga are technically protected as a national park. It contains 27 islands; the largest, Olkhon, is long and is the third-largest lake-bound island in the world. The lake is fed by as many as 330 inflowing rivers.〔 The main ones draining directly into Baikal are the Selenga River, the Barguzin River, the Upper Angara River, the Turka River, the Sarma River, and the Snezhnaya River. It is drained through a single outlet, the Angara River. Despite its great depth, the lake's waters are well-mixed and well-oxygenated throughout the water column, compared to the stratification that occurs in such bodies of water as Lake Tanganyika and the Black Sea. Baikal-S1999276045323.png |Lake Baikal as seen from the OrbView-2 satellite Ice Melting on Lake Baikal - NASA Earth Observatory.jpg |Spring ice melt underway on Lake Baikal Circles in Thin Ice, Lake Baikal, Russia.jpg |Circle of thin ice, diameter of at the lake's southern tip, probably caused by convection Selenga delta.jpg|Delta of the Selenga River, Baikal's main tributary 26 swiatoinos.jpg|Mountains seen from the banks of Baikal 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lake Baikal」の詳細全文を読む スポンサード リンク
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