Why does Earth have mountains?Why does Earth have mountains? Where do they come from?Where do they come from?

Why are there ocean fossils at Why are there ocean fossils at the top of the Himalayas?the top of the Himalayas?

Why does California have Why does California have Earthquakes?Earthquakes?

Where do volcanoes come from?Where do volcanoes come from?

Plate TectonicsPlate Tectonics

Chapter 8Chapter 8

Alfred WegenerAlfred Wegener

Continental DriftContinental Drift Wegener thought Wegener thought

whole sections of the whole sections of the crust moved crust moved

EvidenceEvidence Shape of ContinentsShape of Continents Rock EvidenceRock Evidence

Same mountains on Same mountains on different continentsdifferent continents

Fossil EvidenceFossil Evidence Same fossils on Same fossils on

different continentsdifferent continents

Continental DriftContinental DriftAfrica and South Africa and South

America look like America look like they fit togetherthey fit together

Click on the picture to Click on the picture to see the evidencesee the evidence

1.1. Ancient Mountain Ancient Mountain BeltsBelts

2.2. Ancient Sand DunesAncient Sand Dunes

3.3. Fossil EvidenceFossil Evidence

Continental DriftContinental DriftFossil Fossil EvidenceEvidence

- Same - Same fossilsfossils found found on different on different continentscontinents

1.1. MesosaurusMesosaurus

2.2. LystrosaurusLystrosaurus

3.3. GlossopterisGlossopteris

4.4. CynognathusCynognathus

Continental DriftContinental Drift

What the hypothesis was missing What the hypothesis was missing was the was the HOW?HOW? Alfred WegenerAlfred Wegener proposed that the proposed that the

continents were moving on a more continents were moving on a more fluid fluid layerlayer under the under the crustcrust that could that could possibly be moving due to possibly be moving due to internal internal heatheat . . . . . .

He had no way to prove it!He had no way to prove it!

He was right!. . .well mostlyHe was right!. . .well mostly

He died before his He died before his hypothesishypothesis was was accepted as a accepted as a theorytheory..

New technology allowed scientists to New technology allowed scientists to examine the examine the structure of Earthstructure of Earth They found that the lithosphere was They found that the lithosphere was

moving due to Earth’s moving due to Earth’s internal heatinternal heat.. This developed into the theory of This developed into the theory of Plate Plate

TectonicsTectonics

Who came up with continental Who came up with continental drift?drift?

1 2 3 4

0% 0%0%0%

1.1. Alfred WegenerAlfred Wegener

2.2. Sir Isaac Sir Isaac NewtonNewton

3.3. CopernicusCopernicus

4.4. Alfred Alfred HitchcockHitchcock

What evidence did Alfred What evidence did Alfred Wegener use to support Wegener use to support

continental drift?continental drift?

1 2 3 4

0% 0%0%0%

1.1. Shape of Shape of continentscontinents

2.2. Rock evidenceRock evidence

3.3. Fossil evidenceFossil evidence

4.4. All of the aboveAll of the above

Why could Alfred Wegener not Why could Alfred Wegener not prove continental drift?prove continental drift?

1 2 3

0% 0%0%

1.1. He could not He could not prove the land prove the land movedmoved

2.2. He could not He could not prove how the prove how the land movedland moved

3.3. He didHe did

Where do most earthquakes Where do most earthquakes and volcanoes occur?and volcanoes occur?

1 2 3 4

0% 0%0%0%

1.1. In the middle of In the middle of platesplates

2.2. Along coastsAlong coasts

3.3. Along mountain Along mountain rangesranges

4.4. Along plate Along plate boundariesboundaries

Plate TectonicsPlate Tectonics

EvidenceEvidence Continental Drift (continents fit, fossils, Continental Drift (continents fit, fossils,

rocks)rocks) New EvidenceNew Evidence

Location of Earthquakes and Volcanoes Location of Earthquakes and Volcanoes (p173)(p173)

Magnetism of the ocean floor (p174)Magnetism of the ocean floor (p174) Age of the ocean floor (p175)Age of the ocean floor (p175)

Plate Tectonics EvidencePlate Tectonics Evidence

Earthquakes and Volcanoes:Earthquakes and Volcanoes: Most earthquake and volcano activity Most earthquake and volcano activity

happen along happen along plate boundariesplate boundaries.. Plates are Plates are movingmoving apart, apart, movingmoving together, together,

or or sliding pastsliding past one another. one another. This creates This creates earthquakesearthquakes

Where plates move apart and come together Where plates move apart and come together magmamagma is brought to the surface is brought to the surface

This creates This creates volcanoesvolcanoes

Plate TectonicsPlate TectonicsWorld Earthquakes

See page 712 to view direction See page 712 to view direction of plate movementof plate movement

Plate Tectonics EvidencePlate Tectonics Evidence

Magnetism of the Ocean Floor Magnetism of the Ocean Floor (see page 174)(see page 174)

Mid-ocean Ridges are places where Mid-ocean Ridges are places where NEWNEW rock is forming. rock is forming.

These rocks contain These rocks contain magnetic mineralsmagnetic minerals (minerals with iron) they point to the (minerals with iron) they point to the north polenorth pole

The north pole can The north pole can flipflip with the south pole with the south pole These minerals flip too. This is called a These minerals flip too. This is called a

magnetic reversalmagnetic reversal..

Plate TectonicsPlate Tectonics

Seafloor Magnetism

Video

Plate Tectonics EvidencePlate Tectonics Evidence

Age of the Ocean FloorAge of the Ocean Floor New rock is formed at a New rock is formed at a mid-ocean ridgemid-ocean ridge

or spreading centeror spreading center These are formed in the These are formed in the middlemiddle of the ocean of the ocean

The rock gets The rock gets olderolder as you move away as you move away from the ridgefrom the ridge

The ocean floor is not that old because it The ocean floor is not that old because it subducts under continentssubducts under continents

The oldest ocean floor is ~The oldest ocean floor is ~180 million years 180 million years oldold

Plate Tectonics Plate Tectonics Age of the ocean floorAge of the ocean floor

oldest

youngest

Earth’s StructureEarth’s Structure Crust + Crust + Upper MantleUpper Mantle

= Lithosphere (= Lithosphere (solidsolid)) AsthenosphereAsthenosphere

“fluid” portion of the “fluid” portion of the mantlemantle

Mantle - Mantle - SolidSolid Outer Core – Outer Core – LiquidLiquid Inner Core – Inner Core – SolidSolid

Heat comes from Heat comes from radioactive materialradioactive material in the corein the core

Mantle ConvectionMantle Convection

CompositionComposition

Thick

Low Density

High Silica

Floats

Thin

High Density

Low Silica

Sinks

3 Types of Plate Boundaries:3 Types of Plate Boundaries:

1.1. DivergentDivergent

2.2. ConvergentConvergent

3.3. TransformTransform

Divergent BoundaryDivergent BoundarySea floor spreadingSea floor spreading Large continents Large continents

begin to begin to crackcrack and and splitsplit apart apart

The gaps fill with The gaps fill with waterwater

Small seas become Small seas become oceansoceans

The The mid ocean mid ocean ridgeridge continues to continues to produce new crustproduce new crust

Divergent BoundaryDivergent BoundaryCharacteristicsCharacteristics

2 plates2 plates are moving apart are moving apart Shallow EarthquakesShallow Earthquakes MagmaMagma comes to the surface and cools comes to the surface and cools

BasaltBasalt rock forms rock forms DenseDense and and darkdark in color in color

Creates a Creates a Mid-Ocean RidgeMid-Ocean Ridge Rift valleys form in the centerRift valleys form in the center

Examples: Mid Atlantic Ridge and East Examples: Mid Atlantic Ridge and East Pacific Rise Pacific Rise

Divergent BoundaryDivergent BoundaryHow?How?

The plates are pulled The plates are pulled apart by apart by convection convection currentscurrents in the mantle in the mantle belowbelow

Caused by heat Caused by heat released from natural released from natural radioactiveradioactive processes processes

At mid-ocean ridges At mid-ocean ridges moltenmolten rock from below rock from below rises up to fill the gap rises up to fill the gap with new with new basalticbasaltic rock rock

Let’s Draw a Divergent Let’s Draw a Divergent BoundaryBoundary

Using the Map on page 712-713 Highlight the Divergent Boundaries

True or False: The magnetic True or False: The magnetic polarity of Earth changespolarity of Earth changes

1 2

0%0%

1.1. TrueTrue

2.2. FalseFalse

Magnetic stripes of oceanic crust proves…Magnetic stripes of oceanic crust proves…

1 2 3

0% 0%0%

1.1. Earth is rotatingEarth is rotating

2.2. One piece of One piece of evidence to evidence to prove plate prove plate movementmovement

3.3. That the rocks That the rocks are very oldare very old

Seafloor rock gets older Seafloor rock gets older as…as…

1 2 3

0% 0%0%

1.1. You move away You move away from the mid-from the mid-ocean ridgeocean ridge

2.2. As you move As you move toward the mid-toward the mid-ocean ridgeocean ridge

3.3. As you move into As you move into the mid-ocean the mid-ocean ridgeridge

The Lithosphere is…The Lithosphere is…

1 2 3 4

0% 0%0%0%

1.1. The crust and The crust and the the upperupper mantlemantle

2.2. Another word Another word for mantlefor mantle

3.3. The crust and The crust and asthenosphereasthenosphere

4.4. The inner coreThe inner core

Which layers of the Earth are Which layers of the Earth are solid?solid?

1 2 3 4 5 6

0% 0% 0%0%0%0%

1.1. Inner CoreInner Core

2.2. Outer CoreOuter Core

3.3. MantleMantle

4.4. CrustCrust

5.5. All of the aboveAll of the above

6.6. 1, 3, and 41, 3, and 4

Which layers of the Earth are Which layers of the Earth are liquid?liquid?

1 2 3 4 5 6 7

0% 0% 0% 0%0%0%0%

1.1. Inner coreInner core

2.2. Outer coreOuter core

3.3. MantleMantle

4.4. AsthenosphereAsthenosphere

5.5. CrustCrust

6.6. All of the aboveAll of the above

7.7. 2 and 42 and 4

A divergent boundary is where A divergent boundary is where plates…plates…

1 2 3

0% 0%0%

1.1. Move apartMove apart

2.2. Come togetherCome together

3.3. Slide past each Slide past each otherother

All divergent boundaries All divergent boundaries eventually form…eventually form…

1 2 3 4

0% 0%0%0%

1.1. MountainsMountains

2.2. OceansOceans

3.3. ContinentsContinents

4.4. The moonThe moon

3 Types of Plate Boundaries:3 Types of Plate Boundaries:

1.1. DivergentDivergent

2.2. ConvergentConvergent

3.3. TransformTransform

Convergent BoundariesConvergent Boundaries

2 plates are moving together2 plates are moving together Ocean-OceanOcean-Ocean Ocean-ContinentOcean-Continent

****DeepDeep Earthquakes Earthquakes

Continent-ContinentContinent-Continent

**Earthquakes**Earthquakes

Subduction Zone

Volcanoes Form

Creates Mountain Belts

NO VOLCANOES

32

Convergent Plate Boundaries• Where lithospheric plates are moving towards one another at

their boundary, lithospheric area must be consumed. This is accomplished by subduction or thickening and delamination.

Convergent BoundariesConvergent Boundaries-Subduction--Subduction-

Ocean-Ocean-OceanOcean or Ocean- or Ocean-ContinentContinent The The denserdenser plate always plate always subductssubducts

•Subducting Plate

• more dense

Volcano Forms

Plate Melts

Ocean – Continent Ocean – Continent SubductionSubduction

                                   

        

Ocean – Continent Ocean – Continent SubductionSubduction

The The ocean plateocean plate always subducts always subducts because it is more dense.because it is more dense.

Continental volcanic arcsContinental volcanic arcs or a or a mountain chain of volcanoes form on mountain chain of volcanoes form on the the continental platecontinental plate..

Examples: Examples: Cascades of N. AmericaCascades of N. America

Andes of S. AmericaAndes of S. America

Ocean – Ocean Subduction Ocean – Ocean Subduction

Ocean – Ocean SubductionOcean – Ocean Subduction

The The denserdenser ocean plate always ocean plate always subductssubducts because it is more dense. because it is more dense.

Volcanic island arcsVolcanic island arcs or chains of or chains of volcanic islands form on the volcanic islands form on the OTHER OTHER OCEANOCEAN plate. plate.

Examples: Examples: Aleutian Islands, AlaskaAleutian Islands, Alaska

Mt Pinatubo, PhilippinesMt Pinatubo, Philippines

Mt Fuji, JapanMt Fuji, Japan

Lets Draw a Subduction Lets Draw a Subduction BoundaryBoundary

Collision BoundaryCollision Boundary

Collision BoundaryCollision Boundary

Convergence of IndiaConvergence of India

Collision BoundaryCollision Boundary

There is There is NO SUBDUCTIONNO SUBDUCTION because because both plates are both plates are continentalcontinental and have and have low densitylow density..

They They buckle upbuckle up forming mountains forming mountains (not (not volcanoesvolcanoes))

Examples: Himalayas, India/AsiaExamples: Himalayas, India/Asia

Highlight and Label the Highlight and Label the Major Convergent Major Convergent

BoundariesBoundaries

Using the Map on page 712-713 Highlight the Divergent Boundaries

What tectonic plate ALWAYS What tectonic plate ALWAYS subducts?subducts?

1 2 3 4

0% 0%0%0%

1.1. Oceanic plateOceanic plate

2.2. Continental Continental plateplate

3.3. BothBoth

4.4. NeitherNeither

What convergent boundary can What convergent boundary can form volcanoes?form volcanoes?

1 2 3 4 5 6

0% 0% 0%0%0%0%

1.1. Ocean – oceanOcean – ocean

2.2. Ocean – Ocean – continentcontinent

3.3. Continent – Continent – continentcontinent

4.4. All of the aboveAll of the above

5.5. 1 and 21 and 2

6.6. 3 and 43 and 4

What is an example of a What is an example of a continental volcanic arc?continental volcanic arc?

1 2 3 4 5 6

0% 0% 0%0%0%0%

1.1. HawaiiHawaii

2.2. CascadesCascades

3.3. HimalayasHimalayas

4.4. AndesAndes

5.5. 2 and 42 and 4

6.6. All of the aboveAll of the above

What is an example of a What is an example of a volcanic island arc?volcanic island arc?

1 2 3 4 5 6 7

0% 0% 0% 0%0%0%0%

1.1. HawaiiHawaii

2.2. Mt. PinatuboMt. Pinatubo

3.3. CascadesCascades

4.4. HimalayasHimalayas

5.5. Mt. FujiMt. Fuji

6.6. 2 and 52 and 5

7.7. All of the aboveAll of the above

What plate subducts in a What plate subducts in a collision boundary?collision boundary?

1 2 3

0% 0%0%

1.1. The more dense The more dense continental platecontinental plate

2.2. Both continental Both continental platesplates

3.3. Neither Neither continental platecontinental plate

What is an example of a What is an example of a collision boundary mountain collision boundary mountain

range?range?

1 2 3 4 5 6 7

0% 0% 0% 0%0%0%0%

1.1. HawaiiHawaii

2.2. Mt. PinatuboMt. Pinatubo

3.3. CascadesCascades

4.4. HimalayasHimalayas

5.5. Mt. FujiMt. Fuji

6.6. 1, 2, and 41, 2, and 4

7.7. All of the aboveAll of the above

3 Types of Plate Boundaries:3 Types of Plate Boundaries:

1.1. DivergentDivergent

2.2. ConvergentConvergent

3.3. TransformTransform

Transform BoundariesTransform Boundaries

Occur when 2 plates are Occur when 2 plates are sliding past sliding past one anotherone another

Ocean – Ocean – OceanOceanOcean – Ocean – ContinentContinent

Continent - Continent - ContinentContinent No No Volcanic ActivityVolcanic Activity ExamplesExamples

San Andreas FaultSan Andreas Fault Along Ocean FloorAlong Ocean Floor

** Earthquakes!

Let’s Draw a Transform Let’s Draw a Transform BoundaryBoundary

Highlight and Label the Highlight and Label the Major Transform BoundariesMajor Transform Boundaries

Using the Map on page 712-713 Highlight the Transform Boundaries