|
The Mariana Trench or Marianas Trench〔Variant according to the U.S. National Geospatial-Intelligence Agency〕 is the deepest part of the world's oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about long but has an average width of only . It reaches a maximum-known depth of 10,994 m (± 40 m) or 6.831 mi (36,070 ± 131 ft) at the Challenger Deep, a small slot-shaped valley in its floor, at its southern end,〔 although some unrepeated measurements place the deepest portion at . At the bottom of the trench the water column above exerts a pressure of , over 1000 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%, making 95 litres of water under the pressure of the Challenger Deep contain the same mass as 100 litres at the surface. The temperature at the bottom is 1 to 4 °C.〔(infoplease.com – The Temperature in the Mariana Trench ), read 2012-05-13〕 The trench is not the part of the seafloor closest to the center of the Earth. This is because the Earth is not a perfect sphere; its radius is about less at the poles than at the equator.〔David R. Williams (17 November 2010).(Earth Fact Sheet ). National Space Science Data Center. Retrieved 23 March 2012.〕 As a result, parts of the Arctic Ocean seabed are at least closer to the Earth's center than the Challenger Deep seafloor. Xenophyophores have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of below the sea surface. On 17 March 2013, researchers reported data that suggested microbial life forms thrive within the trench. ==Names== The Mariana Trench is named for the nearby Mariana Islands (in turn named Las Marianas in honor of Spanish Queen Mariana of Austria, widow of Philip IV of Spain). The islands are part of the island arc that is formed on an over-riding plate, called the Mariana Plate (also named for the islands), on the western side of the trench. 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「Mariana Trench」の詳細全文を読む スポンサード リンク
|