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circumpolar current
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The circular flow of water around Antarctica resulting from the juncture of the west-wind drifls of the Atlantic Pacific and Indian Oceans.
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hydrosphere
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The aqueous envelope of the Earth, including the oceans, freshwater lakes, rivers, saline lakes and inland seas, soil moisture and vadose water, groundwater and atmospheric vapor.
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hydrosphere
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"The waters of the Earth, as distinguished from the rocks (lithosphere), living things (biosphere), and the air (atmosphere). Includes the waters of the ocean; rivers, lakes, and other bodies of surface water in liquid form on the continent; snow, ice, and glacier; and liquid water, ice, and water vapor in both the unsaturated and saturated zones below the land surface. Included by some, but excluded by others, is water in the atmosphere, which includes water vapor, clouds, and all forms of precipitation while still in the atmosphere."
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Glomar Challenger
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A research vessel designed specifically for marine geology studies, including the collection of drill-core samples from the deep ocean floor. In 1968, the vessel embarked on a year-long scientific expedition, criss-crossing the Mid-Atlantic Ridge between South America and Africa and drilling core samples at specific locations. When the age of the samples were determined by paleontologic and isotopic dating studies, they provided the clinching evidence that proved the seafloor spreading hypothesis.
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continental shelf
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a. The gently sloping tread around a continent, extending from the low-water line to the depth of approx. 100 fathoms (183 m), at which depth there is a marked increase of slope toward the great depths.
b. The submerged prolongation of the land mass of the coastal state, consisting of the seabed and subsoil of the shelf, the slope, and the rise.
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continental shelf
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That part of the continent that is covered by water. Continental shelves are more than 322 km wide and about 122 m deep. At the edges of the shelves the continental slope drop rapidly from 100 to 200 m to 3000 to 3700 m.
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continental slope
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a. The declivity from the offshore border of the continental shelf at depths of approx. 100 fathoms (600 ft or 183 m) to oceanic depths. It is characterized by a marked increase in gradient.
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continental margin
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The submarine edge of the continental shelf, from which the continental slope descends. In the modern world this margin generally lies about 200 meters (~600 feet) below sea level.
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continental margin
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a. The zone separating the emergent continent from the deep sea bottom. It generally consists of the continental shelf, the continental slope, and the continental rise.
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bathymetry
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The study and mapping of sea-floor topography.
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ocean floor
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The oceanic crust is mostly basalt, undeformed, and, due to plate tectonics, younger than 150 million years old.The major features of the ocean floor are oceanic ridge, abyssal floor, seamount, trenches and continental margin.
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oceanic floor
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"The bed or bottom of the ocean. A comparatively level valley bottom; any low-lying ground surface"
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abyssal plain
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An area of the ocean floor with a slope of less than 1 in 1,000 or flat, nearly level areas that occupy the deepest portions of many ocean basin.
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abyssal plain
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The broad expanse of sea floor lying between about 3 and 6 kilometers (-2 to 4 miles) below sea level.
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abyssal hill
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The hill rising as much as 1000m above the surrounding floor of the ocean. They exist seaward of the abyssal plain where they become covered by sediment.
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continental rise
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A more gently sloping region along the base of the continental slope. The continental rise is a depositional feature formed of sediment transported down the slope often by turbidity current.
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continental rise
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The submarine surface beyond the base of the continental slope, generally having a gradient of less than 1:1,000, occurring at depths from 4,500 to 17,000 ft (1.37 to 5.18 km), and leading down to abyssal plain
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deep-sea fan
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Continental derived sediment located seaward of large rivers or submarine canyon having a cone-shape or fan-shape.
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submarine canyon
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An elongated, steep-walled cleft running across or partially across the Continental Shelf, the continental borderland and/or slope, the bottom of which grades continually downwards
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trench
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"A long and narrow deep trough in the sea floor; interpreted as marking the line along which a plate bends down into a subduction zone. "
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oceanic ridge
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"A continuous, seismic, median mountain range extending through the North and South Atlantic Oceans, the Indian Ocean, and the South Pacific Ocean. It is a broad, fractured swell with a central rift valley and usually extremely rugged topography; it is 1 to 3 km in elevation, about 1,500 km in width, and over 84,000 km in length. According to the hypothesis of sea-floor spreading, the mid-ocean ridge is the source of new crustal material"
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ridge (mid-ocean)
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A major linear elevated landform of the ocean floor, from 200 to 20,000 kilometers in extent. It is not a single ridge, but resembles a mountain range and may have a central rift valley.
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guyot
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A flat-topped submerged mountain or sea-mount found in the ocean.
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atoll
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A continuous or broken circle of coral reef and low coral island surrounding a central lagoon.
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submarine fan
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Fan or cone-shaped accumulation of sedimentary debris--sand, gravel, mud--under the ocean along the edge of the land, either a continent or a volcanic arc. Fans may be a few miles to a hundred or so miles across.
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seamount
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An elevation of the sea floor, 1000 m or higher, either flat-topped (called a guyot) or peaked (called a seapeak). Seamounts may be either discrete, arranged in a linear or random grouping, or connected at their bases and aligned along a ridge or rise
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swell
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An oceanic water wave with a wavelength on the order of 30 meters or more and a height of perhaps 2 meters or less that may travel great distances from its source.
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turbidity current
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A mass of mixed water and sediment that flows downhill along the bottom of an ocean or lake because it is denser than the surrounding water. It may reach high speeds and erode rapidly (see also Density current).
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bioturbation
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Disturbance of oceanic sediment near the water interface by bottom-dwelling (benthic), organisms, for example, burrowing worms.
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gyre
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The circular rotation of the waters of each major sea, driven by prevailing winds and the Coriolis effect.
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density current
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A subaqueous current that flows on the bottom of a sea or lake because entering water is more dense due to temperature or suspended sediment.
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tsunami
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Literally harbor wave in Japanese. Tsunamis are great sea waves produced by a submarine earthquake, volcanic eruption or large landslide. Tsunamis can cause great damage due to flooding of low coastal areas.
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eustatic change
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Sea level changes that affect the whole Earth.
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manganese nodule
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A small, rounded concretion found on the deep ocean floor that may contain as much as 20 percent manganese and smaller amounts of iron, copper, and nickel oxides and hydroxides.
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upwelling current
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The upward movement of cold bottom water in the sea, which occurs when wind or currents displace the lighter surface water.
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black smokers
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"Seafloor hydrothermal fluids jetting from chimneys typically about 10 cm in radius. Flow rates are ~ 1-5 m/s; temperature is 350ø-400ø C. Black coloration is due to sulfide mineral precipitates."
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diatom ooze
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A fine muddy sediment consisting of the hard parts of diatom.
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diatom
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A one celled plant that has a siliceous framework and grows in oceans and lakes.
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Radiolarian ooze
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A siliceous deep-sea sediment composed largely of the skeletons of radiolaria. Radiolarite
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carbonate platform
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A submarine or intertidal shelf whose elevation is maintained by active shallow water carbonate deposition.
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abyssal floor
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The relatively flat surface of the deep ocean floor spreading from an oceanic ridge. It consists of the abyssal plain and the abyssal hill.
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oceanic rocks
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Rocks formed in the deep ocean. Includes sedimentary rocks deposited on the deep ocean floor as well as the basalt of the oceanic crust. Commonly include some slices of the underlying mantle (ultramafic rocks) as well.
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sea aerosol
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Colloidal-size particles of substances derived from the sea surface.
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open hydrochemical system
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Portion in which the mass of a chemical element is not conserved locally and migrates across the boundaries of the system in solution as a solute or as a suspended mineral particle.
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echo-sounder
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An oceanographic instrument that emits sound pulses into the water and measures its depth by the time elapesd before they return.
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