Plate TectonicsPlate Tectonics

Plate TectonicsPlate TectonicsPlate BoundariesPlate Boundaries

Causes of Plate TectonicsCauses of Plate Tectonics

Plate TectonicsPlate Tectonics

What is Plate TectonicsWhat is Plate Tectonics

• The Earth’s crust and upper mantle are broken into sections called plates

• Plates move around on top of the mantle like rafts

What is the What is the LithosphereLithosphere??

• The crust and part of the upper mantle = lithosphere–100 km thick –Less dense than the material

below it so it “floats”

What is the What is the AsthenoshereAsthenoshere??

• The plastic layer below the lithosphere = asthenosphere

• The plates of the lithosphere float on the asthenosphere

2 Types of Plates2 Types of Plates

• Ocean plates - plates below the oceans

• Continental plates - plates below the continents

Questions...Questions...• What is the theory of plate tectonics?

• What is the asthenosphere?• What is the connection between the

two?• What are the two types of plates?

Plate BoundariesPlate Boundaries

Plate BoundariesPlate Boundaries

• Divergent Boundary – moving • Convergent Boundary – moving • Transform Fault Boundary – moving

________________________

together

sideways past each other

Divergent BoundariesDivergent Boundaries

• Boundary between two plates that are moving apart or rifting

• RIFTING causes SEAFLOOR

SPREADING

Features of Divergent Features of Divergent BoundariesBoundaries

• Mid-ocean ridges• rift valleys• fissure volcanoes

• subduction zone called a TRENCH

Convergent BoundariesConvergent Boundaries

• Boundaries between two plates that are colliding

• There are 3 types…

Type 1Type 1• Ocean plate colliding with a less

dense continental plate

• Subduction Zone: less dense plate slides under the more dense plate

• VOLCANOES occur at subduction zones

Andes Mountains, Andes Mountains, South AmericaSouth America

Type 2Type 2• Ocean plate colliding with

another ocean plate

• VOLCANOES occur at subduction zones

Aleutian Islands, AlaskaAleutian Islands, Alaska

Type 3Type 3

• A continental plate colliding with another continental plate

• Have Collision Zones:–mountains form.

Transform Fault BoundariesTransform Fault Boundaries

• Boundary between two plates that are sliding past each other

• EARTHQUAKES along faults

San Andreas Fault, CASan Andreas Fault, CA

Questions...Questions...• What are the three types of

boundaries?• What direction do plates go for

each?• Which boundary has a subduction

zone…what occurs at a subduction zone?

Causes of Plate Causes of Plate TectonicsTectonics

What cause plates to move?What cause plates to move?

Convection Currents • Hot magma in the Earth moves

toward the surface, cools, then sinks again.

• Creates convection currents beneath the plates that cause the plates to move.

• The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH

• Subduction Zone: where the less dense plate slides under the more dense plate

• VOLCANOES occur at subduction zones

Explain Pangaea

• This is what type of boundary ?

What are the two types of plates?

Divergent plate boundaries move_______

Tectonic plates move only _______ per year

A. KilometersB. MilesC. CentimetersD. Millimeters

This type of plate movement can result in the formation of mountains and/or volcanoes

What is the lithosphere?

Two transformative plates slide past each other. What geological event is likely to occur?

Questions...Questions...

• How is a convection current formed?

• What are the three types of plate boundaries?

• What causes plates to move?