Plate Tectonics. © 2011 Pearson Education, Ic. Global Plate Boundaries.
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Transcript of Plate Tectonics. © 2011 Pearson Education, Ic. Global Plate Boundaries.
Plate TectonicsPlate Tectonics
© 2011 Pearson Education, Ic.
Global Plate BoundariesGlobal Plate Boundaries
Plate BoundariesPlate Boundaries
►There are 3 main There are 3 main plate boundaries:plate boundaries:
► 1) Convergent 1) Convergent BoundaryBoundary
► 2) Divergent 2) Divergent BoundaryBoundary
► 3) Transform 3) Transform BoundaryBoundary
Types of Plate BoundariesTypes of Plate Boundaries
Draw With Me Draw With Me
1. Convergent 1. Convergent BoundariesBoundaries
►Occurs when 2 Occurs when 2 plates plates collide.collide.
Oceanic plate is Oceanic plate is denser (3.2 g/cmdenser (3.2 g/cm33), ), faster and thinner - it faster and thinner - it is usually forced is usually forced under the under the continental plate continental plate (2.8 g/cm(2.8 g/cm33).).
The rock in the Oceanic plate melts as the The rock in the Oceanic plate melts as the plate sinks. The melted rock rises up plate sinks. The melted rock rises up causing volcanic eruptions.causing volcanic eruptions.
► The area of convergence is called a The area of convergence is called a SUBDUCTION ZONESUBDUCTION ZONE. .
► When two continental plates collide:When two continental plates collide: They are the same density. They are the same density. This causes the plates to fold and bend This causes the plates to fold and bend
(mountain building) as well as earthquakes.(mountain building) as well as earthquakes.
Convergent Boundary Convergent Boundary
► Plates move toward each otherPlates move toward each other► Oceanic crust destroyedOceanic crust destroyed
Ocean trenchOcean trench Volcanic arcVolcanic arc
Example of a Convergent Example of a Convergent Plate BoundaryPlate Boundary
► South America: South America: ► Oceanic Nazca Plate is Oceanic Nazca Plate is
colliding into the South colliding into the South America plate. America plate.
► Producing the Andes Producing the Andes Mountains (volcanoes Mountains (volcanoes along the mountain crest) along the mountain crest) and formed a deep trench and formed a deep trench off the coast in the Pacific off the coast in the Pacific Ocean. Ocean.
http://http://earthguide.ucsd.edu/eoc/earthguide.ucsd.edu/eoc/teachers/t_tectonics/teachers/t_tectonics/p_subduction.htmlp_subduction.html
© 2011 Pearson Education, Inc.
Convergent BoundariesConvergent Boundaries
Let’s do some drawing!Let’s do some drawing!
Divergent Plate BoundariesDivergent Plate Boundaries► Plates are being Plates are being pulled apart pulled apart
by convection currents in the by convection currents in the mantle.mantle.
► As the plates separate along As the plates separate along the boundary, they crack into the boundary, they crack into faults and blocks. Magma faults and blocks. Magma from the mantle rises through from the mantle rises through the cracks. This cools and new the cracks. This cools and new crust is formed along the crust is formed along the boundary.boundary.
► Earthquakes occur along the Earthquakes occur along the faults, and volcanoes form faults, and volcanoes form where the magma reaches the where the magma reaches the surface. surface.
Mid Atlantic RidgeMid Atlantic Ridge
► Mid-Atlantic Ridge is Mid-Atlantic Ridge is a Divergent Plate a Divergent Plate Boundary.Boundary.
► Over 15 000 km long.Over 15 000 km long.► Average height of Average height of
volcanoes - 3 km.volcanoes - 3 km.
► http://http://earthguide.ucsd.edu/earthguide.ucsd.edu/eoc/teachers/eoc/teachers/t_tectonics/t_tectonics/p_seafloorspreading.p_seafloorspreading.htmlhtml
Age of Ocean FloorAge of Ocean Floor
Example of a Divergent Plate Example of a Divergent Plate BoundaryBoundary
http://www.wwnorton.com/college/geo/egeo/http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm#1 animations/ch2.htm#1 The Process of RiftingThe Process of Rifting
Divergent Boundary Divergent Boundary
► Plates move apartPlates move apart► Mid-ocean ridgeMid-ocean ridge
Rift valleyRift valley► New ocean floor New ocean floor
createdcreated
Sea Floor DiagramSea Floor Diagram
© 2011 Pearson Education, Inc.
Generation of a Divergent Generation of a Divergent BoundaryBoundary
Types of Spreading CentersTypes of Spreading Centers
Sea Floor SpreadingSea Floor Spreading►Mid-ocean ridge Mid-ocean ridge – spreading center– spreading center►Subduction zones Subduction zones – oceanic trench – oceanic trench
site of crust destructionsite of crust destruction► http://www.watchknowlearn.org/Video.aspx?http://www.watchknowlearn.org/Video.aspx?
VideoID=698&CategoryID=2464VideoID=698&CategoryID=2464
© 2011 Pearson Education, Inc.
Earthquakes As EvidenceEarthquakes As Evidence
►Earthquake activity mirrors tectonic Earthquake activity mirrors tectonic plate boundaries.plate boundaries.
Global Distribution of Global Distribution of Earthquakes Earthquakes
Transform BoundaryTransform Boundary► Places where plates slide Places where plates slide
past each other sideway.past each other sideway.
► Transform boundaries are Transform boundaries are not marked by spectacular not marked by spectacular surface features, but their surface features, but their sliding motion causes lots of sliding motion causes lots of earthquakesearthquakes..
► The slice of California to the The slice of California to the west of the fault is slowly west of the fault is slowly moving north relative to the moving north relative to the rest of California. rest of California.
The Problems of Haiti…The Problems of Haiti…
Interactive Plate Tectonic Interactive Plate Tectonic Map Map
►http://geology.com/plate-http://geology.com/plate-tectonics.shtmltectonics.shtml
►Go to the following site and complete Go to the following site and complete the activity!the activity!
Earth’s Magnetic FieldEarth’s Magnetic Field
►http://science.howstuffworks.com/http://science.howstuffworks.com/environmental/planet-earth-videos-environmental/planet-earth-videos-playlist.htm#video-29143playlist.htm#video-29143
HOT SPOT VOLCANOES HOT SPOT VOLCANOES
►http://www.wwnorton.com/college/http://www.wwnorton.com/college/geo/egeo/animations/ch2.htm#1 geo/egeo/animations/ch2.htm#1 AnimationAnimation
Examples of Plate BoundariesExamples of Plate Boundaries
Transform Boundary Transform Boundary FeaturesFeatures
► Oceanic Transform Fault Oceanic Transform Fault – ocean floor only– ocean floor only► Continental Transform Fault Continental Transform Fault – cuts across – cuts across
continentcontinent► All transform faults All transform faults
occur between occur between mid-ocean ridge mid-ocean ridge segments.segments.
Global Hotspot LocationsGlobal Hotspot Locations
Hawaiian Island – Emperor Hawaiian Island – Emperor Seamount NematathSeamount Nematath
Plate Tectonics FeaturesPlate Tectonics Features► Seamounts Seamounts
Rounded topsRounded tops► Tablemounts Tablemounts oror guyots guyots
Flattened topsFlattened tops► Subsidence of flanks of mid-ocean ridgeSubsidence of flanks of mid-ocean ridge► Wave erosion may flatten seamountWave erosion may flatten seamount
Detecting Plate Motion with Detecting Plate Motion with SatellitesSatellites
World Map 50 million Years in World Map 50 million Years in FutureFuture
Coral Reef DevelopmentCoral Reef Development
► Fringing reefs Fringing reefs – – develop along develop along margin of landmassmargin of landmass
► Barrier reefs Barrier reefs – – separated from separated from landmass by lagoonlandmass by lagoon
► AtollsAtolls – reefs – reefs continue to grow continue to grow after volcanoes are after volcanoes are submergedsubmerged
Coral Reef DevelopmentCoral Reef Development