Theory of Plate TectonicsTheory of Plate Tectonics

Plate TectonicsPlate Tectonics

Plate 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 AsthenosphereAsthenosphere??

• 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 lithosphere?

• What is the asthenosphere?

• What is the connection between the two?

• What are the two types of plates?

Plate BoundariesPlate Boundaries

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: where the

less dense plate slides under the more dense plate

• VOLCANOES occur at subduction zones

PLATE A

PLATE B

GUIDE QUESTIONS:1.What type of plate is Plate A? What about Plate B? Why do you say so?

GUIDE QUESTIONS:2.Describe what happens to Plate A as it collides with Plate B? Why?

GUIDE QUESTIONS:3. What do you think may happen to the leading edge of plate A as it continues to move downward? Why?

GUIDE QUESTIONS:4. What do you call this molten material?5. What is formed on top of Plate B?

GUIDE QUESTIONS:6. As the plates continue to grind against each other, what other geologic event could take place?

CONTINENTAL &

OCEANIC PLATES

Type 2Type 2

• Ocean plate colliding with another ocean plate

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

ACTIVITY 2.B CONVERGENCE OF TWO OCEANIC PLATES

Aleutian Islands, AlaskaAleutian Islands, Alaska

GUIDE QUESTIONS:ACTIVITY 2.B

1. What are the geologic processes/events that will occur out of this plate movement?

GUIDE QUESTIONS:ACTIVITY 2.B

2. What geologic features might form at the surface of Plate A?

GUIDE QUESTIONS:ACTIVITY 2.B

3.If the edges of Plate A suddenly flicks upward, a large amount of water may be displaced. What could be formed at the surface of the sea?

Video

Type 3Type 3

• A continental plate colliding with another continental plate

• Have Collision Zones:–a place where folded and thrust

faulted mountains form.

ACTIVITY 2.C : CONTINENTANL PLATES CONVERGING

GUIDE QUESTIONS:ACTIVITY 2.C

1. What happened to the strips of clay as they were pushed from opposite ends?

GUIDE QUESTIONS:ACTIVITY 2.C

2. If the strips of clay represent the Earth’s Lithosphere, what do you think is formed in the lithosphere?

GUIDE QUESTIONS:ACTIVITY 2.C

3. What other geologic event could take place with this type of plate movement aside from your answer in Q2?

GUIDE QUESTIONS:ACTIVITY 2.C

4.In terms of consequences on the Earths Lithosphere, how will you differentiate this type of convergent plate boundary with the other two?

Andes Mountains, Andes Mountains, South AmericaSouth America

FORMATION OF HIMALAYAS

FORMATION OF FOLD MOUNTAINS

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

GUIDE QUESTIONS:ACTIVITY 3

1. What are common on the pictures?

GUIDE QUESTIONS:ACTIVITY 3

2. What do you think is happening to the Earth’s crust in those pictures?

GUIDE QUESTIONS:ACTIVITY 3

3. If the event continues for million of years, what do you think will be the effect on the crust?

GUIDE QUESTIONS:ACTIVITY 3

4. Complete the part of the video below to illustrate your answer in Q3.

VIDEO

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

Convection CurrentsConvection 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.

EARTH’S INTERIOR & PLATE TECTONICS

Questions...Questions...

• What causes plates to move?

• How is a convection current formed?