Plate Tectonics 4 Flashcards

Terms Definitions
convergent boundaries include
divergent boundaries include
rifts and ridges
Oceanic Crust
Thinner than Continental Crust (7-10km)More dense than Continental CrustMafic composition
Nuee ardente
"glowing cloud" or "glowing avalanche"
mixture of mud and hot water
a circulation pattern driven by the rising of hot material and the sinking of cold material
driving mechanism for plates is...
bringing together two small atoms with sufficient pressure so that they form a single, larger atom
ocean-continent characteristics
very deep earthquakes and many volcanoeshave thrust faulting--compressionhave trench, accretionary wedge, magmatic arc, and back arc
is earth's outer core solid or fluid?
Felsic composition
higher amounts of silica (SiO2), Al, Na and Kex: granite/diorite (granodiorite)
a zone of low seismic wave velocity that behaves in a ductile manner because of increased temperature and pressure
transform fault
portion of fracture zone between two offset portions of ridge crest
Phenomena of wave propagation formula
Velocity=Travel Distance/ Travel TimeorV=X/T
where does the deepest seismicity form?
at subduction zones
documentation of earthquakes goes back how many years?
what kind of boundry is the san andreas fault?
mantle plumes
narrow columns of hot mantle rock that rise through the mantle, much like smoke rising from a chimney
Kepler's Laws
1) orbit of each planet travels in eclipse motion with the sun as on foci2) A line drawn from sun to the planet sweeps out equal area in equal time3) p2=kd3
Where are the deepest parts of oceans
at subduction zones
Which of the three waves have the slowest velocity?
Surface waves
how big was the Alaskan 1964 Earthquake fault?
800 KM long!
the outer part of the mantle and th crust; 50-100km thick; no clear edge
types of crustal boundaries
middle of oceansocean to oceanocean to continentcontinent to continent
what can transform faults connect?
they can connect convergent and divergent plate boundaries in various combos
How much do you hate your life doing this flash cards right now kelsie?
a lot.
Which of the three waves arrives second?
The shear or s wave
Where do displacements in surface waves decay?
Displacements in surface waves decay away from surface
Oceanic crust vs. continental crust
oceanic is thin and dense. continental is thick and less dense.
What are the three types of tectonic settings?
1. Convergent Margins2. Divergent Margins3. Transform Margins
What direction do surface rayleigh waves travel?
All motion in surface rayleigh waves is vertical and parallel to propagaion direction
How do we measure plate motion?
1. GPS2. Piercing points - two halves of the same structure that have been moved apart by tectonic forces (determined by knowing when the two halves were together and seeing how far they have drifted apart through time.)
name the rift details set up in order from top to bottom
sedimentspillow lavas and sheet flowssheeted dykes gabbro
what happens when magma is still fluid?
small, magnetic particles in the magma align themselves with the Earth's magnetic field.
Do P waves move slower in fluids or solids?
P waves move slower in fluids
Alyssa Vandekerckhove
folds down
oceanic crust is
silica poor
study of earth's magnet feild
oceanic crust sinks beneath a deep-ocean trench
iron minerals
paleomagnetism, show current magnetic north at the time of formation (magnetite especially)
A single large land mass, supercontinent. Made up of all the continents.
no continental force
Problem with original continental drift theory
converent boundary
the boundary between tectonic plates that are colliding
magnetic reversal
a change in earth's magnetic field
which type of volcano is the largest?
rocks on opposite sides of the fracture slide horizontally past each other
oceanic-oceanic convergence
one oceanic plate dives underneath another oceanic plate. forms trenches, subduction zones. forms volcanic island arcs. causes earthquakes. slab pull (Aleutian Islands, Japan Island Arc)
hess deitz
_______ and ______ came up with seafloor and ocean ridges spreading at relatively the same time
subduction zone
The region where oceanic plates sink down into the asthenosphere.
the central part of Earth below the mantle
Mid-ocean ridge
An underwater moutain chain where new ocean floor is formed
use of sound waves to detect and measure objects under water
the name of the single landmass that broke apart 200 mil. years ago and gave rise to today's continents.
what type of plate baundaries do Not create significant amounts of volcanism?
an island arc is created because two _______ lithospheres collided
convergent collision
plates crash into one another creating a mountain range
inner core
a dense sphere of solid iron and nickel
Transform plate boundary
Boundary between two plates that are sliding past each other.
divergent boundary
a plate boundary where two plates move away from each other
rift zone
a set of deep cracks that forms between two tectonic plates that are pulling away from each other
Seafloor spreading
The process that creates new sea floor as plates move away from each other at the mid-ocean ridges
plate tectonics
the theory that the pieces of earth's lithosphere are in constant motion, driven by convection currents in the mantle.
continental- continental convergence
2 plates with same density collide, fold and crumple. form mountains from pushing up against eachother (Himalayas, Appalachians)
continental crust
the topmost layer of earth of which we live on
how are nuee ardentes formed?
callapse of eruption collum, collapse of lava bulge, overspilling of the creater, direct blast
Theory of Continental drift
a theory that all the continents had once been joined together as a single landmass, named pangaea and has drifted apart
What is the earth's magnetic field
currents in the liquid outer core force the solid inner core to spin slightly faster than the earth rotates
What is fossil evidence of continental drift?
1. fossils of identical animals found on S. America and Africa 2. Plant fossils on multiple continents of plants whose seeds could not have drifted that far
A three-dimensional shape
divergent ocean/continental boundary
volcanic arc
Alfred Wagener
Theory of Continental Drift
Will there be another Pangea?
literally, the "middle sphere"-strong, lower part of the mantle between the asthenosphere and the outer core
Plate boundary where lithosphere is created.
Thrust fault
older rocks above younger rocks
increases as go deeper into earth
A mafic, coarse-grained igneous rock composed predominantly of ferromagnesian minerals and with lesser amounts of calcium-rich plagioclase feldspar.
theory of plate tectonics
convection currents drive plates
when plates collide, the denser one sinks below
subduction zone
Andes Mtn.
South American mountain range with many volcanoes made of andesite lava caused by divergent plates
A scientist who studies the forces that make and shape planet earth
most likely to form where two continental plates converge.
Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.
island arc
more dense sinks under the other
seismic waves
when an earthquake happens the vibrations that come from earthquake
Alfred Wegener
credited with the theory of Continental Drift
Large pieces of Earth's crust that move due to Convection Currents.
The areas where sea-floor spreading takes place is
mid-ocean ridge
subduction zones
places where plates are pushed down into the upper mantle
evidence for continental drift
similar rock structures, mountain ranges, rock type, and fossils, climate
l wave
slowest siesmic wave it moves thruogh the earths surface
the layer of rock that forms Earth's outer surface
Continental Drift
the gradual movement and formation of continents (as described by plate tectonics)
continental drift hypothesis
there once was a supercontinent (Pangea) that broke into smaller continents that drifted to their present position
(geology) a crack in the earth's crust resulting from the displacement of one side with respect to the other
sea-floor spreading
the process by which new oceanic lithosphere (sea floor) forms as magma rises to Earth's surface and solidifies at a mid-ocean ridge
the type of stress that occurs when forces act to stretch an object
Earthquake magnitude
measure of ground shaking during and earthquake, which depends of distance from epicenter and the geological material.
mantle convection
movement of mantle that causes plates to move
Richter scale
Measures the ground motion from an earthquake to find the earthquake's strength.
a large crater caused by the violent explosion of a volcano that collapses into a depression
Convergant Boundary
The region where oceanic plates sink down into the asthenosphere., A boundary of tectonic plates where two plates collide
Ancient Climates
coal deposits have been found in Antarctica, glacial deposits have been found on Africa, India, Australia, and South America
Purposed that the continents were all once togethe
Alfred Wegener
Rift Valley
A deep valley that forms where two plates move apart.
<100 km
What is the seismicity of a transform plate boundary?
deep sea trenches
formed when 2 oceanic plates converge and both are pushed back into the mantle
Convergent Boundary
a plate boundary where two plates move toward each other
transform boundary
place where two plates slip past each other, moving in opposite directions
Sheild volcano
A wide gentle slopping volcano made of layers of lava and formed by quiet erruptions.
Deep Sea Trench
At a convergent boundary, the area where an ocean plate is pulled into a convergent boundary
separating plates
when two plates pull away from each other
outer core
the thick liquid layer of the earth made up of iron and nickel
convergent boundaries
plates collide and one is pulled into the mantle and recycled
convergent plate boundary
2 plates coming together / also called destructive plate boundary (continental-oceanic, oceanic-oceanic, continental-continental)
Hot Spot
An area of the earths crust that is weak and allows magma to come up and create volcanos or islands
Constructive Force
a force that means the build up or creation of new land (often formed by cooling magma)
divergent plate boundary
The line between two plates where they are separating and moving in opposite directions. Found over the rising plume of a mantle convection cell. As the plates spread apart magma fills the void forming new crust. Divergent boundaries form new ocean floor
Convergent Boundry (Cont. to Cont.)
When two plates push together causing mountains
Where do plates pull apart?
At a rift of an undersea boundary.
What does convergent boundary do?
It formes by lthe collision of 2 lithospheric plat
What is Wilson's theory of Plate Tectonics?
Pieces of the lithosphere are in slow constant motion driven by convection currents in the mantle
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