Plate Plate

TectonicsTectonics

Chapter 10Chapter 10

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PLATE TECTONIC PUZZLEPLATE TECTONIC PUZZLE

1.1.Reconstruct PangaeaReconstruct Pangaea

2.2.What evidence led to your What evidence led to your conclusion?conclusion?

3.3.What landmasses logically fit What landmasses logically fit together?together?

4.4.What other evidence led you to What other evidence led you to believe the continents fit believe the continents fit together?together?

Early Earth and Plate Tectonics

The early Earth & Plate Tectonics

The Earth’s Drifting The Earth’s Drifting ContinentsContinents

German scientist Alfred Wegener, 1900’s German scientist Alfred Wegener, 1900’s proposed the Theory of Continental Drift… proposed the Theory of Continental Drift… he was not the only one to do this… he was he was not the only one to do this… he was able to collect evidence thoughable to collect evidence though

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1.1.How could you prove

How could you prove

a theory like this?

a theory like this?2.2.How do you convince

How do you convince

people to support

people to support your ideas/thoughts?

your ideas/thoughts?

Evidence Evidence 1.1. Glossopteris (gymnosperm… seed fern), Glossopteris (gymnosperm… seed fern),

located in 250 myo rocks, were found in located in 250 myo rocks, were found in South Africa, Australia, India, and AntarcticaSouth Africa, Australia, India, and Antarctica

2.2. Antarctica once had a warmer climateAntarctica once had a warmer climate

3.3. Rock formations and deposits lined up on Rock formations and deposits lined up on several continentsseveral continents

4.4. Evidence of glaciers in now warm climatesEvidence of glaciers in now warm climates

The EvidenceThe Evidence

Same fossils on different continents

Same species of plants and rock formations on different

continents

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Can you think of any

Can you think of any

other evidence that

other evidence that Wegener could use?

Wegener could use?

The Real Issue………..The Real Issue………..

How could the continents move through the How could the continents move through the solid rock bottoms of the oceans?solid rock bottoms of the oceans?

In the 1950’s, scientists using better In the 1950’s, scientists using better instruments found underwater mountain instruments found underwater mountain chains with rift valleys in their centerschains with rift valleys in their centers

Midocean ridgeMidocean ridge

Earth’s Spreading Ocean Earth’s Spreading Ocean FloorFloor

A. Mid-ocean ridges form the single largest A. Mid-ocean ridges form the single largest mountain range in the world (under the mountain range in the world (under the oceans)oceans)

B. 80,000 km long and 3 km highB. 80,000 km long and 3 km high

C. Lava erupts to form new sea floor C. Lava erupts to form new sea floor

D. As it spreads it takes continents with itD. As it spreads it takes continents with it

This explained the mechanism for continental This explained the mechanism for continental drift!drift!

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Explain to your

Explain to your partner how we know

partner how we know

the sea floor is

the sea floor is spreading.spreading.

Seafloor Spreading

Iceland, "the land of fire and ice",Iceland, "the land of fire and ice", is being split by an is being split by an oceanic ridge that surfaces to create an oceanic island oceanic ridge that surfaces to create an oceanic island in the North Atlantic Ocean. in the North Atlantic Ocean.

Interesting Interesting IcelandIceland

1.1. Slightly smaller than KentuckySlightly smaller than Kentucky

2.2. Average temperature is 11°C (52°F) in July and -1°C (30°F) in Average temperature is 11°C (52°F) in July and -1°C (30°F) in January January

3.3. Natural hazards: Earthquakes and volcanic activity; avalanches Natural hazards: Earthquakes and volcanic activity; avalanches

4.4. Environment issues: Water pollution from fertilizer runoff; Environment issues: Water pollution from fertilizer runoff; inadequate wastewater treatment inadequate wastewater treatment

5.5. More land covered by glaciers than in all of continental Europe More land covered by glaciers than in all of continental Europe

6.6. Number of volcanoes: 43Number of volcanoes: 43

Magnetic stripes on the ocean floor were further Magnetic stripes on the ocean floor were further evidence that the sea floor was spreading. The evidence that the sea floor was spreading. The patterns are identical on each side of the ridgepatterns are identical on each side of the ridge

Closer examination shows that the magnetic Closer examination shows that the magnetic poles have reversed themselves anywhere from poles have reversed themselves anywhere from 9-2,000 times in the past 3.5 million years… 9-2,000 times in the past 3.5 million years… depends on the strength of the field tested.depends on the strength of the field tested.

Pole ReversalPole ReversalThe magnetic pole is currently 966 kilometers The magnetic pole is currently 966 kilometers (600 miles) from the geographic one. (600 miles) from the geographic one.

The magnetic pole lies in the Arctic Ocean… it is The magnetic pole lies in the Arctic Ocean… it is currently migrating toward Siberiacurrently migrating toward Siberia

EarthsMagnetic Field

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LITHOSPHERIC PLATES

Thousands protest against Global Warming!!!

If the ocean floor is being created, is If the ocean floor is being created, is the Earth getting bigger?... Nothe Earth getting bigger?... No

• Rock in the ocean is relatively youngRock in the ocean is relatively young

• Ocean floor is being destroyed in trenches in a Ocean floor is being destroyed in trenches in a process called subductionprocess called subduction

• The denser ocean crust is pushed downward into The denser ocean crust is pushed downward into the mantle and meltsthe mantle and melts

• It is a cycle… some goes down and some goes upIt is a cycle… some goes down and some goes up

Some comes up

Some goes down

The Earth’s Moving PlatesThe Earth’s Moving Plates

The Theory of Plate Tectonics, which links The Theory of Plate Tectonics, which links continental drift and seafloor spreading, continental drift and seafloor spreading, explains how the Earth has evolved over time. explains how the Earth has evolved over time. It helps to explain the formation, movement, It helps to explain the formation, movement, collisions, and destruction of the Earth’s crustcollisions, and destruction of the Earth’s crust

PLATE TECTONICSPLATE TECTONICS

Lithospheric Lithospheric PlatesPlates

There are seven major plates, Pacific, North There are seven major plates, Pacific, North American, South American, Eurasian, African, American, South American, Eurasian, African, Indo-Australian, and AntarcticIndo-Australian, and Antarctic

There are many small plates, Caribbean, There are many small plates, Caribbean, Arabian are examplesArabian are examples

Each plate moves at a different speed and Each plate moves at a different speed and directiondirection

Some are oceanic and some are continentalSome are oceanic and some are continental

Table

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1.1.How would plate

How would plate boundaries act

boundaries act differently if ocean

differently if ocean plates hit each other

plates hit each other

or if ocean plates hit

or if ocean plates hit

continental plates

continental plates2.2.Would there be a

Would there be a difference?difference?3.3.What would happen,

What would happen,

what would form?

what would form?

ACTIVITYACTIVITY1. Label & color the seven major plates2. Answer the questions on the back

Sand Art… Relax while you Sand Art… Relax while you work work

Moody Slide… hopefully it will workMoody Slide… hopefully it will work

Will the Earth Continue to Will the Earth Continue to Change?Change?

The Floating CrustThe Floating CrustIsostasy is the balance between the downward Isostasy is the balance between the downward force of the crust and the upward force of the force of the crust and the upward force of the mantlemantle

Plate BoundariesPlate BoundariesDivergent boundary-Divergent boundary- plates moving apart plates moving apart

C to C forms a rift valley that fills in w/ seawater:Iceland or African Rift Valley

O to O forms a mid-ocean ridge: Mid-Atlantic Ridge

Convergent Convergent boundary-boundary- plates that plates that are moving togetherare moving together

Collision of Collision of Continental and Oceanic Plates = Continental and Oceanic Plates =

Trench and Volcanic ArcTrench and Volcanic Arc

Pacific Coast, Washington State

Collision of Collision of 2 Continental Plates 2 Continental Plates = = Mountain RangeMountain Range

Himalayas (India)

Collision of Collision of 2 Oceanic Plates = 2 Oceanic Plates = Trench and Island Trench and Island

ArcArc

Transform boundary, slip-Transform boundary, slip-strike, lateral faults-strike, lateral faults- plates slide plates slide past one another resulting in past one another resulting in earthquakes earthquakes

San Andreas Fault is this type… and no CA will not fall into the ocean…. LA will be a suburb of San Francisco

Plate MotionPlate MotionThe power of the The power of the convection currentsconvection currents in the in the mantle is thought to be the force that moves mantle is thought to be the force that moves the platesthe plates

The Earth’s Changing The Earth’s Changing SurfaceSurface

Stress is what causes the surface of the Earth to Stress is what causes the surface of the Earth to changechange

As the rocks undergo stress, they slowly change As the rocks undergo stress, they slowly change shape and volumeshape and volume

They also move up and down or sidewaysThey also move up and down or sideways

Types of StressesTypes of Stresses CompressionCompression squeezes the rock (Convergent) squeezes the rock (Convergent)

TensionTension causes the rocks to stretch out over a causes the rocks to stretch out over a larger area (Divergent)larger area (Divergent)

ShearingShearing of the rock causes it to twist or tear of the rock causes it to twist or tear (Transform)(Transform)

FaultingFaultingA break or a crack along A break or a crack along which rocks move which rocks move

Earthquakes are sometimes Earthquakes are sometimes along these faultsalong these faults

If the rock above the fault moves down, the fault is termed normal (tension), whereas if the rock above the fault moves up, the fault is termed reverse (Compression)

Faulted Mountains and Faulted Mountains and ValleysValleys

Mountains formed Mountains formed when there are many when there are many normal faults in one normal faults in one areaarea

Blocks of rock are Blocks of rock are uplifteduplifted

Valleys may form Valleys may form when the block of land when the block of land between 2 normal between 2 normal faults slides downwardfaults slides downward

Folded Folded MountainsMountains

• When stress is applied to the rock formation When stress is applied to the rock formation and it bends but doesn’t breakand it bends but doesn’t break

• Forms an anticline which is an upward fold Forms an anticline which is an upward fold and a syncline which is a downward foldand a syncline which is a downward fold

Anticline v. SynclineAnticline v. Syncline

Synclines Sink

Volcanic Volcanic MountainsMountains

Single peak Single peak mountains formed mountains formed from volcanoesfrom volcanoes

YellowstoneYellowstone

Yellowstone Super Volcano Alert