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Oceanography Vocabulary for First Exam


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the cast body of saline water that occupies the depressions of Earth's surface
Marine Science (or Oceanography)
the process of discovering unifying principles in data obtained from the ocean, its associated life-forms, and the bordering lands.
How much of the Earth's surface is covered by ocean?
70.78 percent
a speculation about the natural world that can be tested and verified
traveling on the ocean for a specific purpose
chart makers
Library of Alexandria
constituted history's greatest accumulation of ancient writings. Considered the first university in the world. When any ship entered the harbor, the books were by law removed and copied.
Eratosthenes of Cyrene
A librarian at the Library of Alexandria and the first to calculate the circumference of Earth
celestial navigation
the technique of finding one's position on Earth by reference to the apparent positions of heavenly bodies.
drawn parallel to the equator
Lines that ran from pole to pole
Polynesian colonizations
the peopling of the central and eastern Pacific islands
a very consistent clock. It doesn't need to tell accurate time, but its rate of gain or loss must be constant and known exactly so that accurate time may be calcuated.
measurement of the depth of a body of water
Global Positiong System (GPS)
Satellite-based navigation system that provides a geographical position-longitude and latitude- accurate to less than 1 meter
radiometric dating
the process of determining the age of rocks by observing the ratio of unstable radioactive elements to stable decay products
an increase in the mass of a body by accumulation or clumping of smaller particles.
big bang
The hypothetical event that started the expansion of the universe from a geometric point; the beginning of time
the initial formation of life on Earth
condensation theory
Premise that stars and planets accumulate from contracting accreting clouds of galactic gas, dust and debris
the mass per unit volume of a substance, usually expressed in grams per cubic centimeter
density stratification
the formation of layers in a material, with each deeper layer being denser than the layer above
a large rotating aggregation of stars, dust, gas, and other debris held together by gravity. There are perhaps 50 billion galaxies in the universe.
Milky Way galaxy
the name of our galaxy; sometimes applied to the field of stars in our home spiral arem, which is correctly called the orion arm
Diffuse cloud of dust and gas
the volcanic venting of volatile substances
a smaller, usually nonluminous body orbiting a start.
a tightly condensed knot of material that has not yet attained fusion temperature.
solar nebula
the diffuse cloud of dust and gas from which the solar system originated
solar system
the sun together with the planets and other bodies that revolve around it
a massive sphere of incandescent gases powered by the conversion of hydrogen to helium and other heavier elements
the explosive collapse of a massive star
absolute dating
deteremining the age of a geological sample by calculation radioactive decay and/or its position in relation to other samples
the hot, plastic layer of the upper mantle below the lithosphere, extending some 350 to 650 kilometers below the surface. Convection currents withing the astenosphere power plate tectonics.
the relatively heavy vrustal rock that forms the seabeds, composed mostly of oxygen, silicon, magnesium, and iron.
the ability of an object to float in a fluid by displacement of a volume of fluid equal to it in mass
the theory that Earth's surface features are formed by catastrophic forces such as the biblical flood. Catastrophists believe in a young Earth and a literal interpretation of the biblical account of Creation
The transfer of heat through matter by the collision of one atom with another
continental crust
the solid masses of teh continents, composed primarily of granite
continental drift
the theory that the continents move slowly across the surface of the earth
movement within a fluid resulting from differential heating and cooling of the fluid. Convection produces mass transport or mixing of the fluid
convection current
a single closed-flow circuit of rising warm material and falling cool material.
convergent plate boundary
a region whree plates are pushing together and where a mountain range, island arc, and'or trench will eventually form; often a site of much seismic and volcanic activity.
the innermost layer of Earth, composed primarily of iron, with nickel and heavy elements. The inner core is thought to be a solid sphere, the outer core a liquid mass.
the outermost solid layer of earth, composed mostly of granite and basalt; the top of the lithosphere. The crust accounts for 0.4 percent of Earth's mass.
Curie point
The temperature aboce which a material loses its magnetism
divergent plate boundary
a region where plates are moving apart and where new ocean or rigt valley will eventually form. A spreading center forms the junction
a sudden motion of earth's crust resulting from waves in Earth caused by faulting of the rocks or by volcanic activity.
echo sounder
A device that reflects sound off the ocean bottom to sense water depth. Its accuracy is affected by the variability of the speed of sound through water.
a fracture in a rock mass along which movement has occurred.
the relatively light crustal rock- composed mainly of oxygen, silicon, and aluminum - that forms the continents.
time required for one-half of all the unstable radioactive nuclei in a sample to decay.
hot spot
a surface expression of a plume of magma rising from a stationary source of heat in the mantle
isostatic equilibrium
Balanced support of lighter material in a heavier, displaced supporting matrix; analogous to buoyancy in a liquid
the brittle, relatively cool outer layer of Earth, consiting of the oceanic and continental crust and the outermost, rigid layer of mantle
lower mantle
the rigid portion of Earth's mantle below the astehonsphere.
molten rock capable of fluid flow; called lava above ground
a device that measures the amount and direction of residual magnetism in a rock sample
the layer of Earth between the crust and the core, composed of silicates of iron and magnesium.
mantle plume
Ascending columns of superheated mantle originating at the core-mantle boundary
oceanic crust
the outermost solid surface of Earth beneath ocean floor sediments, composed primarily of basalt
an assemblage of subduction oceanic lithosphere scraped off (obducted) onto the edge of a continent
P wave (primary wave)
a compressional wave that is associated with an earthquake and that can move through both liquid and rock
Pacific Rings of fire
The zone of seismic and volcanic activitiy that encircles the Pacific Ocean
the "fossil", or remanent, magnetic field of a rock
Name by Alfred Wegener to the original "protocontinent"; the breakup of Pangea gave rise to the Atlantic ocean and the continents we see today.
Name given by Alfred Wegener to the ocean surrounding Pangaea
one of about a dozen rigid segments of Earth's lithosphere that move independently. The plate consists of continental or oceanic crust and the cool, rigid upper mantle directly below the crust.
plate tectonics
The theory that Earth's lithosphere is fractured into plates that move relative to each other and are driven by convection currents in the mantle. Most volcanic and seismic activity occurs at plate margins.
radioactive decay
the disintegration of unstable forms of elements, which releases subatomic particles and heat.
relative dating
determing the age of geological sample by comparing its position to the position of other samples
Richter scale
a logarithmic measure of earthquake magnitude. A great earthquake measures about 8
S wave (secondary wave)
a transverse wave that is associated with an earthquake and that cannot move through liquid
seafloor spreading
the theory that new ocean crust forms at spreading centers, most of which are on the ocean floor, and pushes the continents aside. Power is thought to be provided by convection currents in Earth's upper mantle
seismic waves
a low-frequency wave generated by the forces that cause earthquakes. Some kinds of seismic waves can pass through Earth
an instrument that detects and records earth movement associated with earthquakes and other disturbances
shadow zone
the wide band at Earth's surface 105 degrees to 143 degrees away from an earthquake in which seismic waves are nearly absent. P waves are absent beause they are refracted by Earth's liquid outer core; S waves are absent from this band and the zone immediately opposite the earthquake site because they are absorbed by the outer core
spreading center
the junction between diverging plates at which new ocean floor is being made
the downward movement into the asthenosphere of a lithosphereic plate.
subduction zone
an area at which a lithospheric plate is descending into the astenosphere. The zone is characterized by linear folds (trenches) in the ocean floor and strong deep foucus earthquakes
a very large mantle plume
an isolated segment of seafloor, island arc, plateau, continental crust, or sediment transported by seafloor spreading to a poisition adjacent to a larger continental mass; usually different in composition from the larger mass
abyssal hill
small sediment covered inactive volcano or intrusion of molten rock less than 200 meters high thought to be associated with seafloor spreading
ayssal plain
flat, cold, sediment-covered ocean floor betweent the continental rise and the oceanic ridge at a depth of 3,700 to 5,500 meters
active margin
the continental margin near and area of lithospheric plate convergence
the discovery and study of submerged contours
continental margin
the submerged outer edge of a continent, made of granitic crust; includes the continental shelf and continental slope
continental rise
the wedge of sediment forming the gentle transition from the outer (lower) edge of the continental slope to the abyssal plaing; usually associated with passive margins
continental shelf
the gradually sloping suberged extension of a continent, composed of grantic rock overlain by sediments; has features similar to the edge of the nearby continent
continental slope
the sloping transition between the granit of the continent and the basalt of the seabed; the true edge of a continent.
the point on Earth's surface directly above the focus of an earthquake
fracture zone
area of irregular, seismically inactive topography marking the position of a once-active transform fault.
a flat-topped, submerged inactive volcano
hydrothermal vent
a spring of hot, mineral- and gas- rich sea-water found on some oceanic ridges in zones of active seafloor spreading.
transform fault
a plane along which rock masses slide horrizontally past one another.
transform plate boundary
places where crustal places shear laterally past one another. Crust is neither produced nor destroyed at this typ of junction
the theory that all of Earth's geological features and history can be explained by processes occurring today and that these processes must have been at work for a very long time.
Alfred Wegener
German scientist who proposed the theory of continental drift in 1912.
John Tuzo Wilson
Canadian geophysicist who proposed the theory of plate tectonics in 1965
ice age
one of several periods of low temperature during the last million years. Glaciers and polar ice were derived from ocean water, lowering sea level at least 100 meters
island arc
curving chain of volcanic islands and seamounts almost always found paralleling the concave edge of a trench
ocean basin
deep-ocean floor made of basaltic crust.
oceanic ridge
young seabed at the active spreading center of an ocean, often unmasked by sediment, bulging above the avyssal plain. The boundary between diverging plates.
passive margin
The continental margin near an area of lithospheric plate divergence
a circular or elliptical projection from the seafloor
shelf break
the abrupt increase in slope at the junction between continental shelf and continental slope.
submarine canyon
a deep, v-shaped valley running roughly perpendicular to the shoreline and cutting across the edge of the continental shelf and slope.
an arc-shaped depression in the deep-ocean floor with very steep sides and a flat sediment-filled bottom coinciding with a subduction zone.
turbidity current
an underwater "avalanche" of abrasive sediments thought responsible for the deep sculpturing of submarine canyons and a means of transport for sediments accumulation on abyssal plains.

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