Reading Notes: Plate Tectonics Page
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3 layers= Crust, mantle, core
Compound= a substance composed of 2 or more elements
Crust= the thin and solid outermost layer of the Earth above the mantle
2 types= Continental and Oceanic Crust (oxygen, silicon, aluminium, etc.)
Mantle= the layer of rock between the Earth’s crust and core
Find out by mantle rock and ocean floor (volcanoes, magma)
Core= the central part of the Earth below the mantle
5 physical layers
Outer Core= liquid layer of the Earth’s core that lies beneath the mantle and surrounds the
inner core
Inner Core= solid, dense centre of our planet that extends from the bottom of the outer core
to the centre of the Earth
Lithosphere= divided into pieces called tectonic plates, the solid, outer layer of the Earth
that consists of the crust and the rigid upper part of the mantle
Mesosphere= the strong, lower part of the mantle between the asthenosphere and the
outer core
Asthenosphere= the soft layer of the mantle on which the tectonic plates move
Tectonic plate= a block of lithosphere that consists of the crust and the rigid, outermost part
of the mantle (like ice cubes in a bowl of punch)
Know about earth layers by earthquakes which produce seismic waves shown by machine,
seismograph, studied by seismologists
Continental drift= the hypothesis that states that the continents once formed a single
landmass, broke up, and drifted to their present locations (know because of fossils found in
many places)
One single, huge continent= Pangaea (all earth, Greek)
Existed 245 million years ago, Laurasia and Gondwana= 180 million years ago
Panthalassa= all sea
Mid-ocean ridges= underwater mountain chains that run through Earth’s ocean basins
Sea-floor spreading= the process in which new ocean lithosphere forms as magma rises
toward the surface and solidifies
Evidence= Magnetic Reversals
Magnetic Reversals= magnetic poles change places
Plate tectonics= the theory that explains how large pieces of the Earth’s outermost layer,
called tectonic plates, move and change shape
Boundaries= place where tectonic plates touch
Convergent Boundaries= the boundary formed by the collision of two lithospheric plates
3 types= continental-continental boundaries, continental-oceanic boundaries, oceanicoceanic boundaries
Continental- oceanic collisions= subduction zone
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Divergent boundary= the boundary between two tectonic plates that are moving away from
each other
Forms new sea floor, mid-ocean ridges
Transform boundary= the boundary between tectonic plates that are sliding past each other
horizontally
San Andreas Fault in California
Causes of tectonic plate motions= ridge push, convection, and slab pull
Global Positioning system (GPS) measure the rate of tectonic plate movement, radio signals
Stress= amount of force per unit area on a given material
Deformation= process by which shape of a rock changes because of stress
Compression= stress that occurs when forces act to squeeze an object (mountains may
form)
Tension= stress that occurs when forces act to squeeze an object (mid-ocean ridges)
Folding= the bending of rock layers due to stress
Types of fold= anticlines (upward-arching fold), synclines (down-ward troughlike folds),
monocline (rock layers are folded so that both ends of the fold are horizontal
Fault= a break in a body of rock along which one block slides relative to another
Normal faults= hanging wall to move down relative to the footwall, tension
Reverse Faults= hanging wall to move up relative to the footwall, compression
Strike-slip faults= form when opposing forces cause rock to break and move horizontally
Folded mountains= rock layers are squeezed together and pushed upward; convergent
boundaries where continents have collided
Fault- Block mountains= tension causes large blocks of the Earth’s crust to drop down
relative to other blocks; sedimentary rock layers are tilted up by faulting, produce mountains
with sharp, jagged peaks
Volcanic mountains= located at convergent boundaries where oceanic crust sinks into the
asthenosphere at subduction zone; rock that is melted in subduction zone from magma,
which rises into the Earth’s surface and erupts; form under the sea, islands; ring of fire
Uplift= the rising of regions of the earth’s crust to higher elevations
Subsidence= the sinking of regions of the Earth’s crust to lower elevations
Rebound= process when one area rises without deforming
Subsidence of cooler rocks
Subsidence= occur when lithosphere becomes stretched in rift zone
Rift zone= a set of deep cracks that forms between two tectonic plates that are pulling away
from each other