Mariana Trench ( World's Deepest Part )

The Mariana Trench or Marianas Trench[1] 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 with an average width of 69 kilometres (43 mi). It reaches a maximum-known depth of 10,994 m (± 40 m) or 6.831 mi (36,070 ± 131 ft) at a small slot-shaped valley in its floor known as the Challenger Deep, at its southern end,[2] although some unrepeated measurements place the deepest portion at 11,034 metres (36,201 ft).[3]

At the bottom of the trench the water column above exerts a pressure of 1,086 bars (15,750 psi) (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.[4]

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.[5] 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 by Scripps Institution of Oceanography researchers at a record depth of 10.6 km (6.6 mi) below the sea surface.[6] On 17 March 2013, researchers reported data that suggested microbial life forms thrive within the trench.[7][8]  The Mariana Trench is part of the Izu-Bonin-Mariana subduction system that forms the boundary between two tectonic plates. In this system, the western edge of one plate, the Pacific Plate, is subducted (i.e., thrust) beneath the smaller Mariana Plate that lies to the west. Crustal material at the western edge of the Pacific Plate is some of the oldest oceanic crust on earth (up to 170 million years old), and is therefore cooler and more dense; hence its great height difference relative to the higher-riding (and younger) Mariana Plate. The deepest area at the plate boundary is the Mariana Trench proper.

The movement of the Pacific and Mariana plates is also indirectly responsible for the formation of the Mariana Islands. These volcanic islands are caused by flux melting of the upper mantle due to release of water that is trapped in minerals of the subducted portion of the Pacific Plate.

Grand Central Terminal ( world's largest station )

Grand Central Terminal (GCT; also referred to as Grand Central Station or simply as Grand Central) is a commuter (and former intercity) railroad terminal at 42nd Street and Park Avenue in Midtown Manhattan in New York City, United States. Built by and named for the New York Central and Hudson River Railroad in the heyday of American long-distance passenger rail travel, it covers 48 acres (19 ha) and has 44 platforms, more than any other railroad station in the world. Its platforms, all below ground, serve 41 tracks on the upper level and 26 on the lower, though the total number of tracks along platforms and in rail yards exceeds 100.

The terminal serves commuters traveling on the Metro-North Railroad to Westchester, Putnam, and Dutchess counties in New York State, and Fairfield and New Haven counties in Connecticut. Until 1991, the terminal served Amtrak, which moved to nearby Pennsylvania Station upon completion of the Empire Connection. The East Side Access project is underway to bring Long Island Rail Road service to the terminal.

Grand Central Terminal has intricate designs both on its inside and outside. In addition, it contains a vast interior main concourse. The terminal is one of the world's most visited tourist attractions, with 21.9 million visitors in 2013.

Unlike other Metro-North stations, Grand Central Terminal is not owned by the Metropolitan Transportation Authority, but by a private company known as Midtown TDR Ventures.

Naming

Although the terminal has been officially called "Grand Central Terminal" since the present structure opened, it has "always been more colloquially and affectionately known as Grand Central Station", a name of one of the earlier railroad stations on the same site.[3][4][N 1] "Grand Central Station" is the name of the nearby U.S. Post Office station at 450 Lexington Avenue,[5] but may also refer to the Grand Central – 42nd Street subway station that is located next to the terminal.

Layout

Grand Central Terminal, on 42nd Street

Diagram of the Upper Level of the main Terminal (1939)

The tracks are numbered according to their location in the terminal building. The upper-level tracks are numbered 11 to 42 east to west. Tracks 22 and 31 were removed in the late 1990s to build concourses for Grand Central North. Track 12 was removed to expand the platform between tracks 11 and 13 and track 14 is only used for loading a garbage train. The lower level has 27 tracks, numbered 100 to 126, east to west; currently, only tracks 102–112, and 114–116 are used for passenger service. Odd-numbered tracks are usually on the east side (right side facing north) of the platform; even-numbered tracks on the west.

Grand Central Terminal has both monumental spaces and meticulously crafted detail, especially on its facade.[6] In a February 2013 BBC News article, historian David Cannadine described it as one of the most majestic buildings of the twentieth century.[7] In 2013, Grand Central Terminal hosted 21.6 million visitors, putting it among the ten most-visited tourist attractions in the world.[8]

Its interior has restaurants, such as the Oyster Bar, and various fast food outlets surrounding the Dining Concourse on the level below the Main Concourse, as well as delis, bakeries, newsstands, a gourmet and fresh food market, an annex of the New York Transit Museum, and more than 40 retail stores. Among them are chain stores, including a Starbucks coffee shop, a Rite Aid pharmacy and, as of December 2011, an Apple Store.[9][10] Other chain restaurants include a Shake Shack.[11][12]

Grand Central Terminal's 49 acres (20 ha) basements are among the largest in the city.[13] This includes M42, a "secret" sub-basement under the terminal that contains the AC to DC converters used to supply DC traction current to the tracks. The exact location of M42 is a closely guarded secret and does not appear on maps, though it has been shown on the History Channel program Cities of the Underworld and a Nationa