PLANET EARTH
pp.729-737
Earth’s Interior and Plate Tectonics
Chapter 21, Section 1
Earth’s Interior- pages 729-730
The Earth is made of multiple layers:
CRUST
• topmost layer of
solid and cool rock
 the “plates”
TWO TYPES OF CRUST
OCEANIC
CONTINENTAL
HOW ARE THE TWO TYPES OF CRUST DIFFERENT?
OCEANIC CRUST
~ 4-7 mi. thick
-dense (basalt)
*sinks under
continental crust
CONTINENTAL CRUST
~12-25 mi. thick
-most thick beneath
mountains
-less dense (granite)
than oceanic crust
Nye & Earth’s
Crust Vogue
Song
Thickness of the crust in KILOMETERS
2. ___________
MANTLE
DENSE
• located below the crust (more _______)
80 % of
• ______
earth’s total
volume
-top (outer) part of the mantle and crust=
__________________
LITHOSPHERE (rigid and cool)
-bottom (inner) part of the mantle =
ASTHENOSPHERE (hot, soft, and
_______________________
easily deformed- like chewing gum)
CRUST
LITHOSPHERE = SOLID
MANTL
E
ASTHENOSPHERE =“SOFT”
3. CORE
iron and nickel
• mostly made of _________________
• very hot
2 layers:
1) OUTER CORE
2)INNER CORE
a. Outer core (________
LIQUID metal)- even though
it’s above the boiling point they do not boil due
to high pressure (no gases)
b. Inner core (________
SOLID metal)- very high
____________ so atoms are forced together
PRESSURE
despite the HEAT
______.
Layers of the
Earth (NASA)
Evidence of Earth’s Internal Structure
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
Layers of Earth Mr Lee
PLATE TECTONICS
*Early 1900sGerman scientist =
Alfred
Wegener
_________________
Continental Drift Song
What observations
intrigued Wegener?
• Wegener hypothesized that all of the
continents fit together in the past to form
PANGAEA (Greek: _____________
“ALL LANDS” )
____________
PERMIAN
225 million years ago
PRESENT DAY
650 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
1. ________
FOSSILS – the same kinds of
animals/plants once lived on continents
that are now oceans apart.
Lystrosaurus land reptile
Glossopteris fern
Cynognathus land reptile
Mesosaurus FW reptile
AGE OF ROCKS (ON OCEAN FLOOR)
2. ________________________________
•Rocks are __________
YOUNGER near the center of
the Atlantic Ocean.
• As distance from
the center
increases, the
rocks are
OLDER
_______.
3. ______________________________
MAGNETISM (discovered mid 1960s)
Magnetic Reversals Explained
Seafloor
Animation
3. Magnetism – (discovered mid 1960s)
• bands of rock on the ocean floor have
alternating magnetic polarities
• 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
• Convection
plates.
•
Currents
Explained
Convection &
Plate Movement
Plate Boundaries (pages 734-737)
* Classified how to plates move in relation to each other
DIVERGENT boundary:
_________________
• 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
Examples of Divergent Boundaries
a. MID-ATLANTIC
RIDGE
* ICELAND is right ON the mid-Atlantic Ridge
b. RED SEA
(E. Africa)
Examples of Divergent Boundaries
Crust in Pieces
Song
How is the Red
Sea forming?
Look at
diagrams and
then describe in
your own
words…
CONVERGENT boundary:
_____________________
• Occurs where two plates push together
3 different situations for convergent boundaries…
a.
b.
c.
a. Oceanic – Continental - Oceanic plate is
more _______
DENSE and sinks below the continental
plate. This is called _______________.
SUBDUCTION
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 – OLDER
________ and more
________
DENSE plate sinks below the other.
EXAMPLES OF OCEANIC-OCEANIC CONVERGENT
BOUNDARIES
1. Aleutian Islands, Alaska
EXAMPLES OF OCEANIC-OCEANIC CONVERGENT
BOUNDARIES
2. Japan
c. Continental – Continental –
________
OLDER and more ________
DENSE plate sinks below
the other.
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 ____________
VOLCANOES
and ________________,
EARTHQUAKES especially around the
“RING OF FIRE”
_________
PACIFIC Ocean in the _______________.
What is special about Hawaii?
Hot Spot
Animation
TRANSFORM boundary:
3. ___________________
• Occurs where two plates slide past each
other horizontally- along a fault
Fault = a break in a body of rock. One
block slides relative to the other (lots of
friction)
FAULT
TRANSFORM FAULT BOUNDARY
What do you see? How did this happen?
EXAMPLE OF A TRANSFORM FAULT BOUNDARY
San Andreas FaultCalifornia/Mexico
TRANSFORM FAULT BOUNDARYvisuals…
A Review of Earth’s Interior and Plate Tectonics Video
Divergent
Continental crust
 rift valley
Convergent
Cont/Cont. plates 
mountain range
Transform
Plates move against
each other.
Stress builds up…
Stress is released
earthquake!
Oceanic crust  midocean ridge
Oceanic/Oceanic or
Oceanic/Continental
subduction