Theory of Plate Tectonics: Lithosphere is broken up into many plates that move Lithosphere is broken...
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Transcript of Theory of Plate Tectonics: Lithosphere is broken up into many plates that move Lithosphere is broken...
Theory of Plate TectonicsTheory of Plate Tectonics:
• Lithosphere is broken up into many plates that move
• Interactions when the plates touch, explain most of the Earth’s land and ocean features
• Earthquakes can occur at all plate boundaries
Plate BoundariesTransfor
m
Divergent
Convergent
What happens at a divergent boundary?• Motion: Plates moving apart
• Features/Processes: o Sea floor spreadingo Mid-ocean ridgeo Volcanic activity
Ex: Mid-Atlantic Ridge
Ex: The Great Rift Valley • Divergent
boundary on a continent
• New ocean forming
DivergBound_PC
What happens at a transform boundary?
• Motion: Plates slide past each other
• Features/Processes: Many earthquakes
Ex: San Andreas Fault
What happens at a convergent boundary?• Motion: Plates
are pushed together
• Features depend on which types of plates are converging (details below)
Convergent(oceanic crust vs. continental
crust)• Oceanic subducts under continental because…o The oceanic crust has a greater density
• Trench is created off the coast• Volcanic Mountains created on land due to rising
magma
magma
Ex: The Andes Mountains
Convergent(oceanic crust vs. oceanic
crust)• The OLDER oceanic plate will sink beneath the newero The older plate is denser b/c it has more time to
compact • Trench is created in between the plates• A volcanic island arc is created due to rising magma
mag
ma
Examples: Island Arcs of1. Aleutian Islands, Alaska 2. Japan
3. The Philippines
Convergent(continental vs. continental)• Both plates collide and deform
o neither subducts because both plates have similar, low densities
• The crust thickens as mountains are pushed upwardo metamorphism of rocks takes place from
pressure
Ex: The Himalayas
ConvergMargV2
MotionAtPlate_PC