PLATE TECTONICS. Plate Tectonics The Theory of Plate Tectonics states that the surface of the earth...

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


• 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”


• Divergent

• Examples:– Atlantic Ocean

Mid-Ocean Ridge

– Red Sea

– Iceland

– African Rift Valley


• Convergent– Oceanic-

continental

– Oceanic-Oceanic

– Continental-Continental


• 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


• Oceanic-Oceanic– One Ocean plate sinks under the other

• Subduction

• Forms a Trench

• Forms a Volcanic Island Arc

• Earthquakes

– Examples:• Japan

• Caribbean Islands


• Continental-Continental– Continent crashes into Continent

• No subduction after Continents hit.

• Forms Mountains

• Earthquakes

– Examples:• Himalayas

• Appalachia

• Urals


• Transform Fault– One plate grinds past another

• Deforms the surface

• Earthquakes

– Examples:• San Andreas Fault

• Anatolian Fault – Turkey

• Chaman Fault - Pakistan


• 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.


• 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.


• 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

PLATE TECTONICS. Plate Tectonics The Theory of Plate Tectonics states that the surface of the earth...

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