PLANET EARTHpp.729-737

Earth’s Interior and Plate Tectonics

Chapter 21, Section 1

The Earth is made of multiple layers:

CRUST• topmost layer of

solid and cool rock

the “plates”

Earth’s Interior- pages 729-730

TWO TYPES OF CRUSTOCEANIC CONTINENTAL

HOW ARE THE TWO TYPES OF CRUST DIFFERENT?

OCEANIC CRUST CONTINENTAL CRUST

~12-25 mi. thick-most thick beneath mountains-less dense (granite) than oceanic crust

~ 4-7 mi. thick-dense (basalt) *sinks under continental crust

Nye & Earth’s Crust Vogue Song

Thickness of the crust in KILOMETERS

2. ___________MANTLE• located below the crust (more _______)DENSE• ______ of

earth’s total volume

80 %

-top (outer) part of the mantle and crust= __________________ (rigid and cool)

ASTHENOSPHERE =“SOFT”

LITHOSPHERE

ASTHENOSPHERE-bottom (inner) part of the mantle = _______________________ (hot, soft, and easily deformed- like chewing gum)

LITHOSPHERE = SOLID

MANTLE

CRUST

3. CORE • mostly made of _________________• very hot

2 layers:1) OUTER CORE

2)INNER CORE

iron and nickel

b. Inner core (________ metal)- very high ____________ so atoms are forced together despite the ______.

SOLIDPRESSURE

HEAT

a. Outer core (________ metal)- even though it’s above the boiling point they do not boil due to high pressure (no gases)

LIQUID

Layers of the Earth (NASA)

S waves: can’t travel

through core (outer/liquid)

transverse & can’t travel

through liquid

P waves:can travel

through core but deflected

change in type of matter

Evidence of Earth’s Internal Structure

Layers of Earth Mr Lee

PLATE TECTONICS

*Early 1900s- German scientist =

_________________Continental Drift Song

What observations intrigued Wegener?

Alfred Wegener

• Wegener hypothesized that all of the continents fit together in the past to form ____________ (Greek: _____________ )PANGAEA “ALL LANDS”

PERMIAN 225 million years ago

PRESENT DAY650 million years in under 2 minutes

What evidence exists to support the theory of plate tectonics and

continental drift?How do we know this?

Pangaea’s Moving Farther Apart Song

– the same kinds of animals/plants once lived on continents that are now oceans apart.

1. ________FOSSILS

Glossopteris fernLystrosaurus land reptile

Mesosaurus FW reptile

Cynognathus land reptile

2. ________________________________ AGE OF ROCKS (ON OCEAN FLOOR)•Rocks are __________ near the center of the Atlantic Ocean.

YOUNGER

• As distance from the center increases, the rocks are _______.OLDER

3. ______________________________MAGNETISM (discovered mid 1960s)

Magnetic Reversals Explained

Seafloor Animation

• bands of rock on the ocean floor have alternating magnetic polarities

3. Magnetism – (discovered mid 1960s)

• magnetic patterns (formed when rocks cooled) are symmetrical (same) on either side of the Mid-Atlantic Ridge

Continents are on the tectonic plates and move with the plates.

*Convection currents within the Earth= (hot rock rises…cooler rock falls) moves the plates. • Convection Curr

ents Explained• Convection & Pl

ate Movement

Plate Boundaries (pages 734-737)* Classified how to plates move in relation to each other

_________________ boundary:DIVERGENT

• Occurs where two tectonic plates move apart and create a gap.

• Forms mid-ocean ridge (from rising magma). Hot rock from the asthenosphere rises up and cools to form new igneous rock. Divergent boundary

a. MID-ATLANTIC RIDGE

Examples of Divergent Boundaries

* ICELAND is right ON the mid-Atlantic Ridge

Examples of Divergent Boundaries

b. RED SEA (E. Africa)

How is the Red Sea forming?

Look at diagrams and then describe in your own words…

Crust in Pieces Song

_____________________ boundary:CONVERGENT

• Occurs where two plates push together

3 different situations for convergent boundaries…

a. b.

c.

a. Oceanic – Continental - Oceanic plate is more _______ and sinks below the continental plate. This is called _______________.

DENSESUBDUCTION

DENSER

SUBDUCTION FORMS:TRENCHES

Mountains / Volcanoes

EXAMPLES OF OCEANIC-CONTINENTAL CONVERGENT BOUNDARIES

1. CASCADE RANGE (Northwestern US)

EXAMPLES OF OCEANIC-CONTINENTAL CONVERGENT BOUNDARIES

2. ANDES MOUNTAINS- W. coast of S. America.

b. Oceanic – Oceanic – ________ and more ________ plate sinks below the other. DENSE

OLDER

EXAMPLES OF OCEANIC-OCEANIC CONVERGENT BOUNDARIES

1. Aleutian Islands, Alaska

EXAMPLES OF OCEANIC-OCEANIC CONVERGENT BOUNDARIES

2. Japan

c. Continental – Continental –________ and more ________ plate sinks below

the other. OLDER DENSE

Cont-Cont Animation

EXAMPLES OF CONTINENTAL-CONTINENTAL CONVERGENT BOUNDARIES

HIMILAYAN MOUNTAINS (like MT EVEREST and K2)

The 10 highest mountains in the world are found here

* Convergent Boundaries create ____________ and ________________, especially around the _________ Ocean in the _______________.

EARTHQUAKESVOLCANOES

PACIFIC “RING OF FIRE”

What is special about Hawaii?

Hot Spot Animation

3. ___________________ boundary:

Fault = a break in a body of rock. One block slides relative to the other (lots of friction) FAULT

TRANSFORM• Occurs where two plates slide past each other horizontally- along a fault

TRANSFORM FAULT BOUNDARYWhat do you see? How did this happen?

EXAMPLE OF A TRANSFORM FAULT BOUNDARY

San Andreas Fault- California/Mexico

TRANSFORM FAULT BOUNDARY- visuals…

Divergent Convergent TransformContinental crust rift valley

Oceanic crust mid-ocean ridge

Cont/Cont. plates mountain range

Plates move against each other.

Stress builds up…

Stress is released earthquake!

Oceanic/Oceanic orOceanic/Continental

subduction

A Review of Earth’s Interior and Plate Tectonics Video