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Earth Science - Chapter 13 & 14
Geoffery Force Earth Science Class TEST 3
56
Science
Undergraduate 1
03/20/2011

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Term
Abyssal Plain
Definition
Very level area of the deep-ocean floor, usually lying at the foot of the continental rise.
Term
Active Continental Margin
Definition
Usually narrow and consisting of highly deformed sediments. They Occur where oceanic lithosphere is being subducted beneath the margin of a continent.
Term
Bathymerty
Definition
The measurement of ocean depths and the charting of the shape of topography of the ocean floor.
Term
Biogenous Sediment
Definition
Seafloor sediments consisting of material of marine-organic origin.
Term
Continental Margin
Definition
That portion of the seafloor adjacent to the continents. Includes Shelf, Slope, and Rise.
Term
Continental Rise
Definition
The gently sloping surface at the base of the continental slope.
Term
Continental Shelf
Definition
The gently sloping submerged portion of the margin, extending from the shoreline to the slope.
Term
Continental Slope
Definition
The steep gradient that leads to the deep-ocean floor and marks the seaward edge of the shelf.
Term
Continental Volcanic Arc
Definition
Mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent.
Term
Deep-Ocean Basin
Definition
The portion of the seafloor that lies between the continental margin and the oceanic ridge system.
Term
Deep-Ocean Trench (Trench)
Definition
An elongated depression in the seafloor produced by bending of oceanic crust during subduction.
Term
Deep-Sea Fan
Definition
A cone-shaped deposit at the base of the continental slope. THe sediment is transported to the fan by turbidity currents that follow submarine canyons.
Term
Echo Sounder
Definition
An instrument used to determine the depth of water by measuring the time interval between emission of a sound signal and the return of its sound from the bottom.
Term
Gas Hydrate
Definition
Unusually compact chemical structures made of water and natural gas. Occur beneath permafrost areas on land and under the ocean floor at depths below 525 meters.
Term
Gradded Bedding
Definition
A sediment layer that is characterized by a decrease in sediment size from bottom to top.
Term
Guyot
Definition
A submerged flat-topped seamount.
Term
Hydrogenous Sediment
Definition
Seafloor sediments consisting of minerals that crystallize from seawater. An important example is maganese nodules.
Term
Mid-Ocean Ridge (Oceanic Ridge)
Definition
A continuous elevated zone on the floor of all the major ocean basins and varying in width from 500 to 5,000km. The rifts at the crests of ridges represent divergent plate boundaries.
Term
Oceanic Plateau
Definition
An extensive region on the ocean floor composed of thick accumulations of pillow basalts and other mafic rocks that in some cases exceed 30km in thickness.
Term
Oceanic Ridge
Definition
A continuous elevated zone on the floor of all the major ocean basins and varying in width from 500 to 5,000km. The rifts at the crests of ridges represent divergent plate boundaries.
Term
Oceanography
Definition
The scientific study of the oceans and oceanic phenomena.
Term
Passive Continental Margin
Definition
Margins that consist of a continental shelf, slope, and rise. They are NOT associated with plate boundaries and therefore experience little volcanism and few earthquakes.
Term
Rift Valley
Definition
A deep downfaulted structure along the axis of some ridge sediments.
Term
Seamount
Definition
An isolated volcanic peak that rises at least 1,000 meters above the deep-ocean floor.
Term
Seismic Reflection Profile
Definition
A way to let marine geologists view the rock structure beneath the sediments that blanket much of the seafloor. Strong low-frequency sounds are produced by explosions (depth charges) or air guns. These sound waves penetrate beneath the seafloor and reflect off the contacts between rock layers and fault zones.
Term
Sonar
Definition
An acronym for Sound Navigation And Ranging. The first devices that used sound to measure water depth.
Term
Submarine Canyon
Definition
A seaward extension of a valley that was cut on the continental shelf during a time when sea level was lower, or a canyon carved into the outer continental shelf, slope, and rise by turbidity currents.
Term
Tablemount
Definition
Another name for guyots; submerged, flat-topped seamounts.
Term
Terrigenous Sediment
Definition
Seafloor sediments derived from terrestrial weathering and erosion.
Term
Volcanic Island Arc
Definition
A chain of volcanic islands generally located a few hundred kilometers from a trench where active subduction of one oceanic slab beneath another is occuring.
Term
Turbidite
Definition
Turbidity current deposit characterized by gradded bedding.
Term
Turbidity Current
Definition
A downslope movement of dense, sediment-laden water created when sand and mud on the continental shelf and slope are dislogded and thrown into suspension.
Term
Abyssal Zone
Definition
A subdivision of the benthic zone characterized be extremely high pressures, low temperatures, low oxygen, few nutrients, and no sunlight.
Term
Aphotic Zone
Definition
That portion of the ocean where there is no sunlight.
Term
Benthic Zone
Definition
The marine life zone that includes ANY seabottom surface regardless of its distance from shore.
Term
Benthos
Definition
The forms of marine life that live on or in the ocean bottom.
Term
Biomass
Definition
The total mass of a defined organism or group of organisms in a particular area or ecosystem.
Term
Density
Definition
Mass per unit volume of a substance, usually expressed as grams per cubic centimeter (g/cm3).
Term
Euphotic Zone
Definition
The portion of the photic zone near the surface, where light is bright enough for photosynthesis to occur.
Term
Food Chain
Definition
A succession of organisms in an ecological community through which food energy is transferred from producers through herbivores and on to one or more carnivores.
Term
Food Web
Definition
A group of interrelated food chains.
Term
Intertidal Zone
Definition
The area where land and sea meet and overlap; the zone between high and low tides.
Term
Nekton
Definition
Pelagic organisms that can move indepently of ocean currents by swimming or other means of propulsion.
Term
Neritic Zone
Definition
The marine-life zone that extends from the low tideline out to the shelf break.
Term
Oceanic Zone
Definition
The marine-life zone beyond the continental shelf.
Term
Pelagic Zone
Definition
Open ocean of ANY depth. Animals in this zone swim or float freely.
Term
Photic Zone
Definition
The upper part of the ocean into which any sunlight penetrates.
Term
Photosynthesis
Definition
The process by which plants and algae produce carbohydrates from carbon dioxide and water in the presence of chlorophyll, using light energy amd releasing oxygen.
Term
Phytoplankton
Definition
Algal plankton, which are the most important community of primary producers in the ocean.
Term
Plankton
Definition
Passively drifting or weakly swimming organisms that cannot move independently of ocean currents. Includes microscopic algae, protozoa, jellyfish, and larval forms of many animals.
Term
Primary Productivity
Definition
The amount of organic matter synthesized by organisms from inorganic substances through photosynthesis or chemosynthesis within a given volume of water or habitat in a unit of time.
Term
Pycnocline
Definition
A layer of water in which there is a rapid change of density with depth.
Term
Salinity
Definition
The proportion of dissolved salts to pure water, usually expressed in parts per thousand (‰).
Term
Thermocline
Definition
A layer of water in which there is a rapid change in temperature in the vertical dimension.
Term
Trophic Level
Definition
A nourishment level in a food chain. PLant and algae producers constitute the lowest level, followed by herbivores and a series of carnivores at progressively higher levels.
Term
Zooplankton
Definition
Animal plankton.
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