plate tectonics. plate tectonics the theory of plate tectonics states that the surface of the earth...
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PLATE TECTONICSPLATE TECTONICS
Plate TectonicsPlate Tectonics
• The Theory of Plate Tectonics states that the surface of the earth is broken up into a few large plates and many smaller ones
Plate TectonicsPlate Tectonics
Plate TectonicsPlate Tectonics
• These solid plates float on the semisolid mantle
• The plates interact with each other in three major ways:– Pull away from each other “Divergent”– Move towards each other “Convergent”– Slide past each other “Transform Fault”
Plate TectonicsPlate Tectonics
• Divergent
• Examples:– Atlantic Ocean
Mid-Ocean Ridge
– Red Sea
– Iceland
– African Rift Valley
Plate TectonicsPlate Tectonics
Plate TectonicsPlate Tectonics
Plate TectonicsPlate Tectonics
Plate TectonicsPlate Tectonics
• Convergent– Oceanic-
continental
– Oceanic-Oceanic
– Continental-Continental
Plate TectonicsPlate Tectonics
• Oceanic-Continental– Ocean plate sinks under the continental plate
• Subduction
• Forms a Trench
• Forms a Continental Volcanic Arc
• Earthquakes
– Examples:• West coast of the United States and South America
Plate TectonicsPlate Tectonics
• Oceanic-Oceanic– One Ocean plate sinks under the other
• Subduction
• Forms a Trench
• Forms a Volcanic Island Arc
• Earthquakes
– Examples:• Japan
• Caribbean Islands
Plate TectonicsPlate Tectonics
• Continental-Continental– Continent crashes into Continent
• No subduction after Continents hit.
• Forms Mountains
• Earthquakes
– Examples:• Himalayas
• Appalachia
• Urals
Plate TectonicsPlate Tectonics
• Transform Fault– One plate grinds past another
• Deforms the surface
• Earthquakes
– Examples:• San Andreas Fault
• Anatolian Fault – Turkey
• Chaman Fault - Pakistan
Plate TectonicsPlate Tectonics
• Evidence for Plate Tectonics– Paleomagnetism
• The natural remnant magnetism in rock bodies
• When rock solidifies from the molten state the magnetic crystals that form align with the magnetic field of the earth.
• The Earths magnetic field has flipped many times in the past.
• This shows up as alternating strips of polarity in the rocks of the seafloor.
Plate TectonicsPlate Tectonics
• Evidence for Plate Tectonics– Earthquake patterns
• Most earthquakes happen along plate boundaries and happen at different depths according to the type of boundary.
– Ocean Drilling• Data on age of seafloor crust supports seafloor
spreading.
– Hot Spots• Hawaiian Island chain supports the idea that the plates
are moving.
Plate TectonicsPlate Tectonics
• Mechanisms of Plate Tectonics– Slab-Pull and Ridge-Push
• Slab-Pull – As the slab sinks down into the mantle it pulls the rest of the plate after it.
• Ridge-Push – The push of the magma from the mantle at the ridge causes the material at the top of the ridge to fall down the sides of the ridge.
– Mantle Convection• Currents of rock moving in the earths interior over
millions of years.– Cool rock sinking – Hot rock rising