Download Updated Plate Tectonics

Module F: Chapter 4
Plate Tectonics
Section 1: Inside the Earth
Section 2: Restless Continents
Section 3: The Theory of Plate Tectonics
Section 4: Deforming the Earth’s Crust
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
Inside the Earth
Bell Ringer
Recall your knowledge of the rock cycle, and if you
journeyed to the center of the Earth, what do you think you
would see along the way?
Draw an illustration of the journey in your notes.
End of Slide
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Section 1
Inside the Earth
Objectives
• Identify the layers of the Earth by their composition.
Warning!!!!!!!
• Identify the layers of the Earth by their physical
properties.
You must understand these objectives
• Describe
tectonic plate.
toamaster
this section!!!!!!
• Explain how scientists know about the structure of Earth’s
interior.
Did you read the objectives?
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 1
Inside the Earth
The Composition of the Earth
• The Crust: The outermost layer of the Earth is the crust.
The crust is 5 to 100 km thick. It is the thinnest layer of the
Earth, and it is mainly made of silicate material, which
consists of mostly the elements silicon and oxygen.
• The Mantle: The layer of the Earth between the crust and
the core is the mantle. The mantle is much thicker than the
crust and contains most of the Earth’s mass.
• The Core: The layer of the Earth that extends from below
the mantle to the center of the Earth is the core. Scientists
think that the Earth’s core is made mostly of iron.
End of Slide
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Section 1
The Composition of the Earth
Did you
read the
captions?
End of Slide
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Section 1
The Physical Structure of the Earth
The Physical Structure of the Earth
• Five Physical Layers The Earth is divided into five
physical layers— the lithosphere, asthenosphere,
mesosphere, outer core, and inner core.
• Illustrated Earth The next slides will show these five
layers.
End of Slide
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Section 1
The Earth’s Crust, Lithosphere, & Asthenosphere
Did you read the
captions?
Which layer is
made of tectonic
plates?
End of Slide
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Section 1
The Earth’s Mesosphere, Outer Core, and Inner Core
Did you read the captions?
The inner core
is liquid: true
or false?
End of Slide
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Section 1
Inside the Earth
Tectonic Plates
• A Giant Jigsaw Puzzle: Each tectonic plate fits together
with the tectonic plates that surround it. The lithosphere is
like a jigsaw puzzle, and the tectonic plates are the pieces.
• A Tectonic Plate Close-up: Many tectonic plates not only
consist of the upper part of the mantle but also consist of
both oceanic crust and continental crust.
• Like Ice Cubes in a Bowl of Punch: Tectonic plates
“float” on the asthenosphere. The plates cover the surface
of the asthenosphere, and they touch one another and
move around.
End of Slide
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Section 1
A Tectonic Plate
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Section 1
Tectonic Plates
Does the North American plate consist of
oceanic crust, continental crust, or both?
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Section 1
Tectonic Plates & Movement
In which general direction is the
North American plate moving? End of Slide
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Section 1
Inside the Earth & Mapping
Mapping the Earth’s Interior
• Seismic Waves: When an earthquake happens,
vibrations called seismic waves are produced. Seismic
waves travel at different speeds depending on the density
and composition of material that they pass through.
• Seismographs: When an earthquake happens, machines
called seismographs measure the times at which different
seismic waves arrive and record the differences in their
speeds. Seismologists can then use these measurements
to calculate the density and thickness of Earth’s layers.
End of Slide
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Section 1
Inside the Earth & Mapping
Mapping the Earth’s Interior
P or Primary Waves:
• First to arrive & fastest
• Travel through all states of
matter
• Faster through dense material
• Compression waves: squeeze
or push/pull like a slinky
S or Secondary Waves:
•Second to arrive & slower
• Travel only through solids
• Shear waves: move up &
down like a rope End of Slide
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Section 1
Inside the Earth & Mapping
True or False
Seismographs record S waves first. False
P waves can travel through gases. True
S waves can travel through liquids. False
P waves are called compression waves. True
S waves cannot travel through the Earth’s core. True
End of Slide
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Section 1
Inside the Earth & Mapping
How a seismograph works
• Click on the picture below to open website
• Then click on animation “How a Seismograph Works”
End of Slide
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Section 1
Inside the Earth & Mapping
How Seismic Waves Move
End of Slide
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Section 2
Restless Continents
Bell Ringer
Judge what is meant by the following statement: “The
United States is moving westward.” From what you know
about geology and plate tectonics explain if you believe this
statement to be true or false.
Record your answer in your notes.
End of Slide
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Section 2
Restless Continents
Objectives
• Describe Wegener’s hypothesis of continental drift.
• Explain how sea-floor spreading provides a way for
continents to move.
• Describe how new oceanic lithosphere forms at midocean ridges.
• Explain how magnetic reversals provide evidence for
sea-floor spreading.
End of Slide
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Section 2
Restless Continents
Wegener’s Continental Drift Hypothesis
• What Is Continental Drift? Continental drift is the
hypothesis that states that the continents once formed a
single landmass, broke up, and drifted to their present
locations.
The Breakup of Pangaea
• Pangaea, a single huge continent, existed about 245
million years ago. Pangaea split into two large continents—
Laurasia and Gondwana— about 180 million years ago.
The next slide shows how Pangaea eventually broke up
into the continents that exist today.
End of Slide
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Section 2
The Breakup of Pangaea
End of Slide
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Section 2
The Breakup of Pangaea Animation
Yes! There is a question hidden here! If you’re
ready then click away!
What are the names of the two land masses that
were created when Pangaea broke-up?
Click on the Earth
to view Pangaea’s
breakup & the
future world!
End of Slide
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Section 2
The Breakup of Pangaea: Evidence
Geography
(PuzzleLike)
Sea-Floor
Spreading
Fossil
Record
Continental
Drift
End of Slide
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Section 2
The Breakup of Pangaea & Fossil Record
A scientist named Wegener observed that similar fossils existed on
the different continents.
End of Slide
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Section 2
The Breakup of Pangaea & Geography
Wegener also observed that the
continents fit together like a jigsaw
puzzle, and terrain features like
mountain ranges lined up.
End of Slide
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Section 2
The Breakup of Pangaea & Sea Floor Spreading
Sea-Floor Spreading
• Mid-Ocean Ridges and Sea-Floor Spreading: Midocean ridges are places where sea-floor spreading takes
place. Sea-floor spreading is the process by which new
oceanic lithosphere forms as magma rises toward the
surface and solidifies.
• Evidence for Sea-Floor Spreading: Magnetic
Reversals When Earth’s magnetic poles change places,
this change is called a magnetic reversal.
• Magnetic Reversals and Sea-Floor Spreading Magnetic
reversals are recorded over time in oceanic crust.
End of Slide
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Section 2
The Breakup of Pangaea & Sea Floor Spreading
Where does sea floor
spreading take place?
Where is the youngest
oceanic crust located?
Near the mid-ocean ridge or
away from it?
Are you smarter than a fifth grader? What type of rock is
formed at mid-ocean ridges? The answer is not on the slide
but in your head!
•Click on the picture to the right to open
website
•Then click on “(2.5) Sea Floor Spreading”
to view animation
End of Slide
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Section 2
Sea-Floor Spreading & Magnetic Reversals
•Click on the picture below to open website
•Then view two related animations
• Click on “(2.3) Magnetic Reversals”
• Click on “(2.4) Wandering Poles or Continental
Drift”
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Theory of Plate Tectonics
Bell Ringer
If the sea floor is spreading an average of 4 cm a year, how
many years did it take New York and the west coast of
Africa to reach their current locations, 676,000,000 cm
apart?
Calculate your answer in your notes.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Theory of Plate Tectonics
Objectives
• Describe the three types of tectonic plate boundaries.
• Describe the three forces thought to move tectonic
plates.
• Explain how scientists measure the rate at which tectonic
plates move.
End of Slide
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Section 3
The Theory of Plate Tectonics
Tectonic Plate Boundaries
• Convergent Boundaries: When two tectonic plates
collide, the boundary between them is a convergent
boundary.
• Divergent Boundaries: When two tectonic plates
separate, the boundary between them is called a divergent
boundary.
•Transform Boundaries: When two tectonic plates slide
past each other horizontally, the boundary between them is
a transform boundary.
End of Slide
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Section 3
Convergent Boundaries
Did you read the captions?
End of Slide
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Section 3
Divergent & Transform Boundaries
End of Slide
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Section 3
Tectonic Plate Boundaries: Animation
To view animations for tectonic plate boundaries follow
the instructions below:
1. Click on picture to right to open
a webpage containing the
animations
2. Then go to Exploring Earth
3. Then go to Visualizations
4. Then go to Chapter 8
5. Then go to link with code:
ES0804
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Theory of Plate Tectonics
Possible Causes of Tectonic Plate Motion
• Movement of the Asthenosphere: The solid rock of the
asthenosphere flows very slowly. This movement occurs
because of changes in density within the asthenosphere.
These density changes are caused by the outward flow of
thermal energy from deep within the Earth. As you can see
on the next slide, movements of the asthenosphere may
lead to tectonic plate motion.
Okay! This is a mouthful! Imagine that the Asthenosphere is a big
lava lamp. The heated globs float upward, cool, then sink where
they are reheated, and the cycle starts all over again. Does this
help?
End of Slide
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Section 3
Possible Causes of Tectonic Plate Motion
There are three
possible causes:
Ridge Push, Slab
Pull, and
Convection (the
lava lamp theory)
Convection
Did you read the
captions?
Can you explain
the three theories?
Please raise your hand to let your teacher know that you
End of Slide
are ready to explain one of these theories?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 3
The Theory of Plate Tectonics
Tracking Tectonic Plate Motion
• Measuring Tectonic Plate Movement: Tectonic plate
movements are so slow and gradual that you can’t see or
feel them— the movement is measured in centimeters per
year.
• The Global Positioning System: Scientists use a system
of satellites called the global positioning system (GPS) to
measure the rate of tectonic plate movement.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Deforming the Earth’s Crust
Objectives
• Describe two types of stress that deform rocks.
• Describe three major types of folds.
• Explain the differences between the three major types of
faults.
• Identify the most common types of mountains.
• Explain the difference between uplift and subsidence.
End of Slide
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Section 4
Deforming the Earth’s Crust
Deformation
• What Is Deformation? The process by which the shape
of a rock changes because of stress is called deformation.
• Compression and Tension The type of stress that
occurs when an object is squeezed, such as when two
tectonic plates collide, is called compression. Another form
of stress is tension. Tension is stress that occurs when
forces act to stretch an object.
End of Slide
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Section 4
Deforming the Earth’s Crust
Folding
• What Is Folding? The bending of rock layers because of
stress in the Earth’s crust is called folding.
• Types of Folds The two most common types of folds—
anticlines, or upward-arching folds, and synclines, downward, trough-like folds. Another type of fold is a monocline.
In a monocline, rock layers are folded so that both ends of
the fold are horizontal.
End of Slide
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Section 4
Deforming & Folding
Folding
A: Monocline
B: Anticline
C: Syncline
End of Slide
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Section 4
Deforming & Folding
Which type of fold?
Syncline
End of Slide
End of Slide
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Section 4
Deforming & Folding
Which type of fold?
Anticline
End of Slide
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Section 4
Deforming & Folding
Which type of fold?
Monocline
End of Slide
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Section 4
Deforming the Earth’s Crust
Faulting
• Normal Faults: When a normal fault moves, it causes the
hanging wall to move down relative to the footwall.
• Reverse Faults When a reverse fault moves, it causes
the hanging wall to move up relative to the footwall.
• Telling the Difference Between Faults You can what
kind of fault a fault is by looking at the order of sedimentary
rock layers on each side of the fault.
• Strike-Slip Faults Strike-slip faults form when opposing
forces cause rock to break and move horizontally.
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Deforming the Earth’s Crust
Faulting
1. Click on picture
2. Then go to Exploring
Earth
3. Then go to
Visualizations
4. Then go to Chapter 11
5. Then go to link with
code: ES1103 & ES1105
End of Slide
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Section 4
Deforming the Earth’s Crust
Plate Tectonics and Mountain Building
• Folded Mountains: Folded mountains form when rock
layers are squeezed together and pushed upward.
• Fault-Block Mountains: Fault-block mountains form
when this tension causes large blocks of the Earth’s crust
to drop down relative to other blocks.
• Volcanic Mountains: The rock that is melted in the
subduction zone forms magma, which rises to the Earth’s
surface and erupts to form volcanic mountains.
End of Slide
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Section 4
Deforming the Earth’s Crust
Plate Tectonics and Mountain Building
• Folded Mountains Folded mountains form when rock
layers are squeezed together and pushed upward.
End of Slide
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Section 4
Deforming the Earth’s Crust & Fault Block Mts
Plate Tectonics and Mountain Building
• Fault-Block Mountains Fault-block mountains form when
this tension causes large blocks of the Earth’s crust to drop
down relative to other blocks.
End of Slide
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Section 4
Deforming the Earth’s Crust
Plate Tectonics and Mountain Building
• Volcanic Mountains The rock that is melted in
subduction zone forms magma, which rises to the Earth’s
surface and erupts to form volcanic mountains.
End of Slide
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Section 4
Deforming the Earth’s Crust
Uplift and Subsidence
• Uplifting of Depressed Rocks: Uplift often happens
when a weight is removed from the crust.
• Subsidence of Cooler Rocks: Rocks that are hot take
up more space than cooler rocks. The farther the
lithosphere is from the ridge, the cooler and denser the
lithosphere becomes. Because the oceanic lithosphere now
takes up less volume, the ocean floor subsides.
• Tectonic Letdown: Subsidence can also occur when the
lithosphere becomes stretched in rift zones.
End of Slide
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Section 4
The End
If you are unsure of any concept in
this Power Point presentation, please
review animations in your online
textbook (Visual Concepts). For
further assistance, please complete the
interactive tutorial in your online
textbook (Activities and Quizzes)
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