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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