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The increase in temperature with increasing depth is known as the geothermal gradient and is gradual within the rheological boundary layer. In practice, the RBL is defined by the depth at which the viscosity of the mantle rocks drops below ~ 10 21 P a ⋅ s . {\displaystyle 10^{21}Pa\cdot s.} .
Earth's crust ranges from 5 to 70 kilometres (3.1–43.5 mi) [7] in depth and is the outermost layer. [8] The thin parts are the oceanic crust, which underlies the ocean basins (5–10 km) and is mafic-rich [9] (dense iron-magnesium silicate mineral or igneous rock). [10]
Bathymetric charts showcase depth using a series of lines and points at equal intervals, called depth contours or isobaths (a type of contour line). A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward.
Continental shelves appear mostly by a depth of 140 meters, mid-ocean ridges by 3000 meters, and oceanic trenches at depths beyond 6000 meters. A seafloor map captured by NASA Bathymetry ( / b ə ˈ θ ɪ m ə t r i / ; from Ancient Greek βαθύς ( bathús ) 'deep' and μέτρον ( métron ) 'measure') [ 1 ] [ 2 ] is the study of ...
After the Trieste was retired, the Japanese remote-operated vehicle (ROV) Kaikō was the only vessel capable of reaching this depth until it was lost at sea in 2003. [8] In May and June 2009, the hybrid-ROV Nereus returned to the Challenger Deep for a series of three dives to depths exceeding 10,900 m (35,800 ft; 6.8 mi).
Layers of the pelagic zone. The bathypelagic zone or bathyal zone (from Greek βαθύς (bathýs), deep) is the part of the open ocean that extends from a depth of 1,000 to 4,000 m (3,300 to 13,000 ft) below the ocean surface. It lies between the mesopelagic above and the abyssopelagic below.
Historically, the hadal zone was not recognized as distinct from the abyssal zone, although the deepest sections were sometimes called "ultra-abyssal".During the early 1950s, the Danish Galathea II and Soviet Vityaz expeditions separately discovered a distinct shift in the life at depths of 6,000–7,000 m (20,000–23,000 ft) not recognized by the broad definition of the abyssal zone.
The GEBCO chart series was initiated in 1903 by an international group of geographers and oceanographers, under the leadership of Prince Albert I of Monaco.At that time there was an explosion of interest in the study of the natural world and this group recognized the importance of a set of maps describing the shape of the ocean floor.