Plate TectonicsBOUNDARIES

Chapter 17

Learning Targets:• What are the three types of plate boundaries?• What features can be found at each one?

Plate Tectonics

• Earth’s crust is cracked into smaller pieces called PLATES

• Looks like a cracked egg shell• There are two types of crust

– Continental crust– Oceanic crust

Plate Boundaries

• Divergent Boundary– Moving away

• Convergent Boundary– Moving together

• Transform Boundary– Sliding past each other

Plate Tectonics• Divergent Plate Boundaries

– Magma comes up pushing plates away – New rocks are created– Mid-Ocean Ridge = largest divergent

boundary• Underwater Mountain Range

– Called a Rift Valley if on land• Great Rift Valley in Africa

Watch Animation

Plate Tectonics

• Divergent Boundary– Plates are moving AWAY from each

other – I need 2 Volunteers!– DIVergent DIVorce

Plate Tectonics• Convergent Boundaries

– There are 2 main types of Convergent Boundaries

• First one is when an oceanic plate meets a continental plate

Oceanic – Continental Boundary

• Oceanic Crust is denser than Continental Crust

• Oceanic Crust gets SUBDUCTED underneath Continental Crust– Subduction goes underneath

• Creates a Trench and Volcanoes – Example: Mt. St. Helens

Watch Animation!

Continental – Continental Boundary

• Plates have same densities– No subduction

• Plates Collide and land goes UP• Mountains are created

– Paper Demo• Example: Himalayan Mountains

(Mt. Everest)

Plate Boundaries

• Convergent Boundaries– Plates moving TOWARDS each other– Need 2 more Volunteers!

– Convergent Connecting or COUPLE

Plate Boundaries• Transform Boundary

– A.k.a Sliding boundary– One plate is sliding horizontally past another

plate– Earthquakes are common at these

boundaries– The San Andreas Fault (California) is the

most well known example

Watch Animation