Plate Tectonics 11 Flashcards

Terms Definitions
reverse fault
greek for "all earth"
seafloor spreading
paleomagnetism, mapped topography using sonar of seafloor showed linear mountain ranges in the middle of high heat flow and volcanism at ridge
rock changes because of rock
Continental fit
Observation of plate tectonics, measures along continental slope especially South America and Africa fit together
transform plate baundaries are not know for
ocean ridges
driving force behind plate tectonics, production of new crust, pushes old crust away causes plates to move since the Earth is not expanding crust must be destroyed at trenches elsewhere
machines which measure the times at which seismic waves arrive at different distances from an earthquake
plate boundaries
places where tectonic plates interact (come together, move apart, or slide horizontally past each other)
continental drift
the hypothesis that the continents slowly move acrosss earth's surface.
what type of plate boundary is responsible for the ring of fire?
this volcano is made of alternating layers of viscous lavas and pyroclast
Animal whose fossil, a small reptile who was freshwater and could not have swam across the ocean, was found both on the continents of Africa and South America
magnetic reversals
switches in magnetism of ocean crust, convinced people of plate tectonics
Convection currents
circular movement of a substance due to changes in temperature and density.
the thin and solid outermost layer of Earth above the mantle
reverse fault
when hanging walll moves up relative to the footwall
the study of the record of earth's magnetism
rigid layer of Earth about 100 km think, made of the crust and part of the upper mantle
stress that occurs when forces act to squeeze an object
Convergent boundary
mountains can form
convection current
the flow that transfers heat within a fluid
mid ocean ridge
An underwater moutain chain where new ocean floor is formed
global positioning system
measures the rate of tectonic plate movement
transform boundary
a plate boundary where two plates move past each other in opposite directions
Convergent plate boundary
A plate boundary where tectonic plates move towards each other.
deep-ocean trench
a deep valley along the ocean floor beneath which the oceanic crust slowly sinks toward the mantle.
a break in the body of rock along which one block slides relative to another
sea-floor spreading
new sea floor as plates move away from each other
Who is Alfred Wegener?
German scientist who came up with hypothesis of continental drift
describe the seafloor spreading
magma makes new crust and pushes the crust apart
Which ocean is growing insize? Which is shrinking?
Atlantic is growing, Pacific is shrinking
where does a hot spot meet a divergent boundary?
Iceland, Mid atlantic ridge
oceanic crust
Convergent Boundary
Plates collide
area above the epicenter
convergent boundries
plates moveing together
Earthquakes, rift valleys, volcanoes
Divergent -
above ground, above the focus
organism whose fossil provided evidence for continental drift, fossilized leaves of an extinct plant found in South Africa, Australia, India and Antarctica
mantle elements
silicon, oxygen, iron, and magnesium
As these types of _____________ currents cool at the Earth's surface, they sink, dragging some of the crustal plates down in subduction at convergent plate boundaries.
behind the idea of plate tectonics
transform fault boundary result
results in earthquakes
Colliding Plates (Convergent)
..Plates moving towards eachother
-ocean plate colliding with another ocean plate.
-the less dense plate slides under the more dense plate creating a subduction zone called TRENCH.
Alfred Wegner thought that the continents was toga
energy that is radiated or transmitted in the form of rays or waves or particles
Rift valley
steep, narrow valley formed as lithospheric plates separate
transform fault boundaries
active sections have many earthquakes
Bends in rock that form when compression shortens and thickens part of earths crust.
contintental drift
hypothesis that continents move slowly across Earth's surface to their current locations
normal fault
Caused by a divergent plate boundary--as two plates divide, the hanging wall falls.
Very large mantle plume; underlies the african continent and is breaking the continent apart.
Charles Darwin
\"Origin of the Species Through Natural Selection\" - 1859
Plate Tectonic Theory
Earth's lithosphere is broken into sections, and movement causes changes to Earth's surface
why did early mapmakers think the continents had moved?
matching coastlines
tectonic plates
a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle
divergent boundaries
(divide) a plate boundary at which plates move apart
the layer of the earth between the crust and the core. Is a layer hot but solid rock.
divergent boundary
The place, usually along the mid-ocean ridges, where two plates move apart
mantle plume
A burst of magma from the mantle
reverse polarity
rocks that don't show the same magnetism as the present magnet field
subduction boundary
converging boundary where 1 plate is over-riding the other one.
ricter scale
This rates the size of seismic waves
Subduction Zones
Places where the seafloor is forced under continental plates
List and describe the evidence used to support the plate tectonics theory.
what is the consistenct of the outer core
ocean plates
if they converge a subduction zone forms
Magnetic reversal
Changes in Earth's magnetic field over geologic time, recorded in ocean-floor rocks and continental basalt flows.
Sketch and label Earth's layers.
See p. 10 F.
active volcano
a volcano that is currently erupting, showing signs that it's going to erupt , or erupted at any time during recorded history
volcanic island arc
Linear group of volcanoes that form due to subduction of an oceanic plate under another oceanic plate
Mid Atlantic Ridge
Where the north and south American plates move away from the Eurasian and African plates
What is it called when the Earth's magnetic poles change places?
magnetic reversal
Hot Spot
Magma flows from a weak spot/vent in the crust creating a volcano
Convergent (continent to continent) boundary
no subduction occurs, instead mountains are formed that are not volcanic
Continental Drift Theory
theory proposed by Alfred Wegener in 1915 that continents drifted apart based on matching coastlines of continents, matching rock types, geographical features, fossils, coal deposits indicating similar climates in areas that are no far apart from each other, etc. not accepted though by scientific community b/c there was no explanation for what moved the continents
Constructive forces
A force that builds up mountains and landmasses on earth's surface
The ocean was just one single body of water called
Heat transfer
When you touch a hot pot or pan, energy moves from the pot to your hand this is called...
Name All The Earth's Layers..?
Inner Core, Outer Core, Mantle, Lithosphere, Asthenosphere, Crust
love waves
when P and S waves reach the surface they become surface waves, move only along the surface of the Earth, travel more slowly and are more destructive.
what are the two landmass that pangea formed called
gondwana and laurasia
where two plates are moving towards each other and one subducts under another
Where do convergent boundaries form?
Ocean to Continent Boundary
A type of onvergent boundary, where an oceanic plate and a continental plate collide and the oceanic subducts under the continental.
What is Land Land convergent?
When 2 land plates clash into each other. ( e.g. Mount Everest)( shallow earthquake)
Richter scale of Earthquakes
One step on the scale is a power of ten in energy (magnitude); R =5 is ten times the power of R = 4.
What are the causes of earthquakes in California?
the Pacific plate is shoving into and under the North American plate and shifting 3 inches a year. This puts stress on on the earthquake faults and it causes an earthquake.
Plate tectonics
inner core
is solid
where earthquakes originate
focus (underground)
Sea-floor spreading occurs along?
Mid-Ocean RidgeS
a boundary where earth's tectonic plates move away from each other, causing formations like mid-ocean ridges and rift valleys
The uppermost layer of the mantle
a linear downfold in sedimentary strata; the opposite of anticline
A destructive plate margin where oceanic crust is being pushed down into the mantle beneath a second plate.
What is ocean crust made of?
Plates slide past each other, resulting in earthquakes.
ex. San Andreas Fault
a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return
2 types of crust layers
Continental & Oceanic
describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color
seafloor spreading:
theory that magma moving upward spreads seafloor apart at mid ocean
What was the reaction to Wegner's theory
is a sign of an explosive volcano
Mountain Range
formed by two continental plates convergint
describes magma or igneous rock that is rich in feldspar and silica and that is generally light in color
fossil found in africa and south america
subduction oceanic trench
when two oceanic plates collide
quake after biggest quake in a sequence
When tectonic platres seperate they create what ty
Divergent Boundry
destructive force
A force that slowly wears away mountains and other features on the surface of Earth.
subduction zone
A boundary where one plate- usually made of dense, oceanic crust- collides and sinks under less dense crust
this type of stress pulls apart rocks, stretches like taffy and is thinner in the middle
Outer Core
The liquid part of Earth's interior made up of iron and nickel.
the amount of matter in a given space
This type of magma has the lowest melting temperature.
mid-ocean ridge
the undersea mountain chain where new ocean floor is produced.
Shield Volcano
A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava
A dark, dense, igneous rock with a fine texture, found in oceanic crust.
Plate Boundary
the region where two tectonic plates are in contact
a trace of an ancient organism that has been preserved in a rock
igneous rocks created at the MOR show magnetic tendencies because basalt contain iron
cinder cone
A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening
amount of force per unit area that is placed on an object
constructive force
A force that builds up mountains and landmasses on Earth's surface
Glossopteris plant
a fossil plant that helps support the theory of continental drift
pressure+temp decreases
what changes from the center of earth to the surface
matching mountain ranges
this piece of evidence might explain why you might find similar rock structures of the Andes Mountains in non-south american countries
From Divergent boundaries
What happens to cause sea floor spreading?
Strike Slip Fault
Plates get "stuck" then when the pressure is too much they will slip past one another and cause an earthquake.
Earth's Crust
A layer of rock that forms Earth's outer layer (skin).
near ocean ridges
is where you find the youngest ocean floor
hot less dense material below the earths crust rises towards the earths surface at mid ocean ridge. then it flows sideways carrying the seafloor away from the ridge in both directions.
sea floor spreading thing
Theory of Plate Tectonics
The theory that states that the plates of the earth move, pushed by convection currents.
Glaciers and naturally-forming salt
Other than the mantle, what are other examples of "flowing" solids? (2 things)
What was the southern section called/had?
Gondwanaland. made of S. Am., Africa, india, australia, antarctica
Uneven. Because an even distribution would imply no convection or hot spots, thus, we would not see plate movement or islands like Hawaii in the middle of a plate.
Is the Distribution of heat within the Earth even or uneven? How do you know?
What is the safest place to be during an earthquake?
go outside and stay away from power lines, buildings
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