8.2T

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BOUNDARIES

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3 main types• Divergent• Convergent• Transform

TYPES OF PLATE BOUNDARIES

Divergent boundary (aka spreading center): a boundary between 2 lithospheric plates that are moving apart

DIVERGENT BOUNDARIES

Most are in the ocean

Have rift valleys

deep valleys at the center of a mid-ocean ridge

Molten rock forces its way up through cracks (rifts)

Older crust is pushed away from the mid-ocean ridge

DIVERGENT BOUNDARIES CONT’D

Fracture zones: broken segments in the lithosphere that are perpendicular to the ridge

DIVERGENT BOUNDARIES CONT’D

A boundary between 2 plates that are moving toward each other

Subduction boundary

Collision boundary

CONVERGENT BOUNDARIES

Subduct: when the denser plate moves under another plate

Subduction boundary: boundary between 2 plates where one plate is pulled beneath another

Deep-Sea Trench: forms along this boundary when 2 oceanic plates converge

Deepest part of the ocean

has a chain of volcanic islands (volcanic island arc) on the upper plate

SUBDUCTION BOUNDARIES

When oceanic and continental plates converge, the denser oceanic plate is subducted

A deep-sea trench is formed

Mountain chain and volcanoes form on the upper continental plate

SUBDUCTION BOUNDARIES CONT’D

If 2 converging plates have continents then they may be pushed together to make a larger continent

Collision boundary

Causes the Earth’s crust to move upward to form mountains

https://www.youtube.com/watch?v=HuSHOQ6gv5Y

COLLISION BOUNDARIES

A boundary between 2 plates that are sliding past each other

Does not move at the same rate

San Andreas Fault

https://www.youtube.com/watch?v=ZxPTLmg0ZCw&spfreload=10

https://www.youtube.com/watch?v=hqR2_sHDfvs

TRANSFORM BOUNDARIES

Answer the following questions.

Use complete sentences.

You may NOT use your book. You MAY use your notes.

This is a quiz grade.

1)Explain how each type of boundary moves.

2)How are the 3 kinds of convergent boundaries different?

8.2 EXIT TICKET