Mariana Trench

The deepest part of Earth’s oceans, where the Pacific Plate is subducted under the Mariana Plate

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The Mariana Trench or Marianas Trench is located in the westernPacific Ocean about 200 kilometres (124 mi) east of the Mariana Islands; it is the deepest trench on Earth. It is crescent-shaped and measures about2,550 km (1,580 mi) in length and 69 km (43 mi) in width. The maximum known depth is 10,984 metres (36,037 ft) (± 25 metres [82 ft]) at the southern end of a small slot-shaped valley in its floor known as the Challenger Deep.However, some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft). By comparison: if Mount Everest were placed into the trench at this point, its peak would still be over two kilometres (1.2 mi) under water.Location of the Mariana Trench

At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%. The temperature at the bottom is 1 to 4 °C (34 to 39 °F).

The trench is not the part of the seafloor closest to the center of the Earth. This is because the Earth is an oblate spheroid, not a perfect sphere; its radius is about25 kilometres (16 mi) smaller at the poles than at the equator. As a result, parts of the Arctic Ocean seabed are at least 13 kilometres (8.1 mi) closer to the Earth’s center than the Challenger Deep seafloor.^{[citation needed]}

In 2009, the Marianas Trench was established as a United States National Monument. Monothalamea have been found in the trench by Scripps Institution of Oceanography researchers at a record depth of 10.6 kilometres (6.6 mi) below the sea surface. Data has also suggested that microbial life formsthrive within the trench.

Names

The Mariana Trench is named after the nearby Mariana Islands (in turn named Las Marianas in honor of Spanish QueenMariana 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.

Geology

The Pacific plate is subducted beneath the Mariana Plate, creating the Mariana trench, and (further on) the arc of the Mariana Islands, as water trapped in the plate is released and explodes upward to form island volcanoes and earthquakes .