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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 underwater depth of ocean floors (seabed topography), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography.
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.
The depth was determined (rather inaccurately) by the time it took to surface. [3] Jacob Perkins (1766–1849) proposed a bathometer based on the compressibility of water. [ 4 ] In this instrument the movement of a piston compressing a body of water enclosed in its cylinder is dependent on the pressure of the water outside the cylinder, and ...
A depth gauge is an instrument for measuring depth below a vertical reference surface. They include depth gauges for underwater diving and similar applications. A diving depth gauge is a pressure gauge that displays the equivalent depth below the free surface in water. The relationship between depth and pressure is linear and accurate enough ...
These instruments are used primarily to measure the elevation or altitude of a celestial object: Back staff, the best known of which is the Davis' quadrant. It could measure the altitude of the Sun without having the navigator directly observe the Sun. Cross staff, an older instrument long out of use.
A sailor and a man on shore, both sounding the depth with a line. Depth sounding, often simply called sounding, is measuring the depth of a body of water.Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seabed topography.
The instrument is lowered into the water in what is called the downcast to a determined depth or to a few meters above the ocean floor, generally at a rate of about 0.5 m/s. Most of the time a conducting wire cable is attached to the CTD frame connecting the CTD to an onboard computer, and allows instantaneous uploading and real time ...
Objectives of marine geophysics include determination of the depth and features of the seafloor, the seismic structure and earthquakes in the ocean basins, the mapping of gravity and magnetic anomalies over the basins and margins, the determination of heat flow through the seafloor, and electrical properties of the ocean crust and Earth's mantle.