Tuesday 24 April 2012

MARIANA TRENCH

MARIANA TRENCH


The Mariana Trench or Marianas Trench 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 2,550 kilometres (1,580 mi) long but has a mean width of only 69 kilometres (43 mi). It reaches a maximum-known depth of about 10.91 kilometres (6.78 mi) (35,800 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 11.03 kilometres (6.85 mi).
At the bottom of the trench, where the plates meet, the water column above exerts a pressure of 1,086 bars (15,750 psi), over one thousand times the standard atmospheric pressure at sea level. At this pressure the density of water is increased by 4.96%, making ninety five litres of water under the pressure of the Challenger Deep contain the same mass as a hundred litres at the surface.
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 25 kilometres (16 mi) less 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.
Xenophyophores have been found in the trench at a record depth of 10.6 km (6.6 mi) below the sea surface.The discovery was made by researchers at the Scripps Institution of Oceanography

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