OCN Chapters 1-3
passive
____ margins include shelf, slope, and rise that extends toward the deep ocean basins
atlantic
____ ocean has simplest and most symmetrical pattern
passive margins
_____ are formed by sea floor spreading and rifting of continental landmasses
pacific
_____ ocean has least symmetrical pattern because many subduction zones around it
coral reef
a calcareous organic reef composed of solid coral and coral sand
convection cell
a circular moving loop of matter involved in convective movement (circular movement of rock material in the mantle)
magnetic field
a condition found in the region around a magnet or an electric current, characterized by existence of a detectable magnetic force at every point in the region and by the existence of magnetic poles
tablemounts
a conical volcanic feature on the ocean floor resembling a seamount except that is has had its top truncated to a relatively flat surface
active margins
a continental margin marked by a high degree of tectonic activity, such as those typical of pacific rim
passive margins
a continental margin that lacks a plate boundary and is marked by a low degree of tectonic activity, such as those typical in the Atlantic ocean -embedded into lithospheric plates and lack major tectonic activity
barrier reef
a coral reef separated from nearby landmass by open water
rift valley
a deep fracture or break extending along the crest of a mid ocean ridge
magnetometer
a device used for measuring the magnetic field of earth
terrane
a distinct geological fragment of crustal material broken off from one tectonic plate and accreted or sutured onto another plate
magnetic anomaly
a distortion of the regular pattern of earth's magnetic field resulting from the various magnetic properties of local concentrations of ferromagnetic minerals in earth's crust
spreading center
a divergent plate boundary
east pacific rise
a fast spreading divergent plate boundary extending from gulf of california to south pacific ocean
transform faults
a fault with side to side motion that offsets segments of a mid ocean ridge -give mid ocean ridge its zigzag appearance
continental shelf
a gently sloping depositional surface extending from the low water line to the depth of a marked increase in slope around the margin of a continent or island
nematath
a linear chain of islands and/or seamounts that are progressively older in one direction created by passage of lithospheric plate over a hotspot
mid ocean ridge
a linear volcanic mountain range that extends through all major oceans; source of new oceanic crustal material
mid ocean rigde
a linear, volcanic mountain range that extends through all major oceans
sounding
a measured depth of water beneath a ship
sonar
a method that uses sound to determine distance of objects in the ocean
wilson cycle
a model that uses plate tectonic processes to show the distinctive life cycle of ocean basins during their formation, growth, and destruction
oceanic rises
a portion of the global mid ocean ridge system that is characterized by fast spreading and gentle slopes
oceanic ridges
a portion of the global mid ocean ridge system that is characterized by slow spreading and steep slopes
seismic reflection profile
a profile view of the structure beneath the sea floor produced by energy generated from explosions or air guns
fringing reefs
a reef directly attached to a shore of an island or continent
atoll
a ring shaped coral reef growing upward from a submerged volcanic peak
mantle plume
a rising column of molten magma from earth's mantle
seismic movement magnitude
a scale used for measuring earthquake intensity based on energy released in creating very long seismic waves
ping
a sharp high pitched sound emitted from echo sounder
mid atlantic ridge
a slow spreading divergent plate boundary running north south and bisecting the atlantic ocean
fathom
a unit of depth in the ocean; equal to 1.83 meters
spreading
amount of energy released by earthquakes on divergent plate boundaries is closely related to ____ rate
pangaea
an ancient supercontinent of geological past that contained all of earth's continents
volcanic arc
an arc shaped row of active volcanoes directly above subduction zone
continental arc
an arc shaped row of active volcanoes produced by subduction that occurs along convergent active continental margins
island arc
an arc shaped row of volcanic islands
precision depth recorder
an early type of sonar device that uses high frequency sound beams to a depth of 1 meter -maps produced by this method confirm ideas of sea floor spreading and plate tectonics
seamounts
an individual volcanic peak extending over 1000 meters above ocean floor
intraplate features
any feature that occurs within a tectonic plate and not along a plate boundary
transform boundary
are found where lithospheric plates slowly grind past one another
deep ocean basins
areas of ocean floor that have deep water, are far from land, and are underlain by basaltic crust
Vine and Matthews
combined unrelated pattern of magnetic sea floor stripes with process of sea floor spreading to explain magnetic stripes on the sea floor
lower
deep areas (trenches) correspond to ____ gravitational attraction
echo sounder
device that transmits sound from a ship's hull to the ocean floor where it is reflected back to receivers -depth determined by travel time of sound signal
continental transform fault
fault that cuts across a continent
seabeam
first multibeam echo sounder -emits multiple beams of sound that are reflected off the ocean floor
lava
fluid magma coming from opening in earth's surface
magma
fluid rock material from which igneous rock is derived through solidification
igneous rocks
form from solidification of molten or partly molten material (magma)
divergent boundary
found along ocean ridges where new lithosphere being added
convergent boundary
found where plates where moving together and one plate subducts against another
slab pull
generated by pull of weight of a plate as it sinks underneath an overlying plate and pulls rest of plate behind it
alfred wegener
german meteorologist and geophysicist was first to advance idea of mobile continents
plate tectonics
global dynamics having to do with movement of semirigid sections of Earth's crust
continental accretion
growth or increase in size of a continent by gradual external addition of crustal material
convective
heat moves to surface with magma in ____ motion
polarity
intrinsic polar separation, alignment, or orientation, especially of a physical property
panthalassa
large, ancient ocean surrounding pangaea
subduction zone
long, narrow region beneath earth's surface in which subduction takes place
atlantic pacific
major outcome of plate tectonic events has been creation of ____ ocean continuing to grow and ___ ocean shrinks b/c of subduction
oceanic transform fault
most common types, occurs wholly on ocean floor
trenches
most large earthquakes occur along ocean _____ this reflects energy released during subduction
magnetite
naturally magnetic iron mineral (nearly all igneous rocks contain this)
trenches
ocean floor being destroyed at ocean ________
san andreas fault
one of the best studied faults in the world; continental transform fault that cuts through california
continental margins
one of the main provicences of the ocean floor that is shallow and close to land
deep ocean basins
one of the main provinces of ocean floor that contains deeper areas further from land
mid ocean ridge
one of the main provinces of ocean floor that contains tall volcanic mountain range
mid ocean ridge
other earthquakes occur along _____ this reflects energy released during sea floor spreading
lithosphere
outer layer of Earth's structure (crust and upper mantle)
asthenosphere
plastic layer in upper mantle that may allow lateral movement of lithospheric plates and isostatic adjustments
transform faulting
process by which a transform fault moves with side to side motion -produces shallow but often strong earthquakes in lithosphere
sea floor spreading
process that moves ocean floor away from ridge axes
transform
regardless the type of ____ fault, always occur between two segments of a mid ocean ridge
sedimentary rock
rock resulting from consolidation of loose sediment
continental drift
sea floor spreading is the best evidence to support _____ ______
slab suction
subducting plate pulls mantle flow towards subduction zone
earthquakes
sudden releases of energy caused by fault movement or volcanic eruptions
continental drift
term applied to early theories supporting idea that continents move across earth's surface through time
magnetic dip
the degree to which a magnetic particle points into earth (directly related to latitude)
bathymetry
the measurement of ocean depth and charting of the shape of the ocean floor -involves measuring vertical distance from ocean surface down to the sea floor
rifting
the movement of two plates in opposite directions such as along a divergent boundary
mid ocean ridges
the ocean floor is youngest here and increase in age as they move away from here
subduction
the process by which one lithospheric plate descends beneath another as they converge
heat flow
the quantity of heat flow to earth's surface per unit of time
hotspots
the relatively stationary surface expression of a persistent column of molten mantle material rising to the surface
fast slow
the slope of ___ spreading segments is less steep than slope of ____ spreading segments
paleomagnetism
the study of earth's ancient magnetic field
paleogeography
the study of historical changes of shapes and positions of the continents and oceans
continental margins
the submerged area next to a continent comprising the continental shelf, continental slope, and continental rise
subsidence
to sink to a low or lower level
basalt
volcanic rock characteristic of ocean crust (comprises ocean crust)
oceanic
when an oceanic plate and continental plate converge, denser _____ plate is subducted
neither
when two continental plates converge _____ plate subducts b/c both too low in density instead create a tall mountain range
oceanic
when two oceanic plates converge, the denser ____ plate is subducted
plate boundaries
where plates interact with each other
