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

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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

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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

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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