Download Plate Tectonics Class Notes

Plate Tectonics
The Earth’s Crust in Motion…
Essential Question:
• What is the theory of
continental drift?
Continental Drift…
Most scientists believe that millions of years
ago, Earth was very different from the way
it is today. There was only one super
continent. Over time, the continent broke
apart, becoming today’s seven continents.
The Continental Drift Theory
In 1910 Alfred Wegener begins
to wonder…
What’s the relationship
Between the continents?
Perhaps all these pieces used to be connected.
Continental drift=slow movement over
Earth’s surface
300 million years ago…
What is the theory of Continental Drift?
 Alfred Wegener first proposed the theory
of continental drift.
Continental Drift is a
theory that states that the continents
were once a single landmass that broke
apart and moved into the positions
they are today.
 Wegener named this
supercontinent Pangaea.
Supercontinent
Pangaea – all lands
•Reptiles and insects
•Tropical forests
-coal deposits
Tens of Millions of years!
Pangaea Puzzle…
• Can you and your team mate
create the super-continent
Pangaea?
This is
how the
continents
fit
together!
Pangaea
means all
lands.
Evidence to Support the Theory
• Fossils of tropical plants found on an
island in the Arctic Ocean are evidence for
the theory of continental drift.
• Pieces of the continents fit together like
pieces of a puzzle.
Evidence to Support the Theory
• Wegner studied fossils of the Lystrosaurus an
animal that lived in fresh water.
• He found fossils of this animal on both the
continents of South America and Africa.
• Mountain Ranges of different continents
seem to match. A mountain range on the
Eastern United States and Canada match
mountain ranges in Greenland and
Europe.
Evidence to Support the Theory
• Diamonds found in African &
South American coal mines
Are the same size and
clarity.
Theory Rejected!!
 Wegener’s theory was rejected by scientists
during his day, because he could not
explain what force pushes or pulls
continents apart.
• 1. The idea that continents move slowly
on Earth’s surface is known as
____________ _____________.
• 2. _______ _______ was the scientist
who put forth the idea of continental drift.
• 3. Wegener’s evidence for continental drift
included all of the following EXCEPT:
• a. matching fossils.
• b. matching mountain ranges.
• c. matching river beds.
• d. matching coal beds.
QOTD 1-19-12
Fossils of Lystrosaurus, an early landdwelling reptile, have been found in
Antarctica, India, and South Africa.
The distribution of these fossils
suggests that these areas were once
•
•
•
•
a.
b.
c.
d.
made of the same chemical elements.
covered by oceanic crust.
home to a wide variety of organisms.
connected to one another.
•
WAC ATTACK…
Explain how Pangaea
supports the theory of
continental drift.
Question of the Day 3-25-14
• 1. The crust and solid upper mantle is called
the _____________.
• 2. It moves on top of a thick syrupy layer called
the ______________.
• 3. Why did the lithospheric plates break apart
and move?
• 4. If a fossil of a tropical plant was found on an
island in the Arctic, what would this reveal
about its past?
Essential Question:
• What is plate tectonic
theory?
Structure of the Earth’s Interior
Now, scientists believe
that…
 The upper mantle and crust make
up the lithosphere.
 The asthenosphere is a soft layer
that can bend like plastic.
 The lithospheric
Plates float and move
On top of the
asthenosphere.
How does it work?
Plates – pieces of the
lithosphere
Plates fit closely
together along cracks
called Plate Boundaries
Convection Currents 
movement
How does it work?
 How is heat is
transferred in the
mantle? Is it by
radiation,
conduction, or
convection.
 Convection is heat
transfer by the
movement of
heated liquid.
Lithospheric Plates
 The lithosphere is broken into separate
sections called plates.
 The geological theory that states that
pieces of Earth’s lithosphere are in
constant, slow motion, driven by
convection currents in the mantle is plate
tectonics.
Earth’s Puzzle
• What plate do we live on?
• What plates do we border?
• USGS Earth’s Plates
• How far do we move every year?
Review Time!!
1. Earth’s crust is divided into
sections called ____________.
Review Time!!
2. How many major sections is Earth’s
crust divided into?
Review Time!!
3. The place where plates meet is called
a…
Review Time!!
4. Most volcanoes and
earthquakes are located
at the ………..…between
two tectonic plates
Essential Question:
• How do lithospheric plates
move?
• How do the different types
of movement create
different landforms?
Types of Boundaries
• Divergent
• Convergent
• Transform
Divergent Boundaries
 The place where two plates move apart or
diverge is called a divergent boundary.
 When a divergent boundary develops on land,
two of Earth’s plates slide apart.
 A deep valley called a rift valley forms along the
divergent boundary.
Convergent Boundaries
 A convergent boundary is where two
plates come together, or converge. The
result of the plates hitting together is called
a collision.
Transform Boundaries
 A transform boundary is a place
where two plates slip past each other,
moving in opposite directions.
 These transform boundaries cause
EARTHQUAKES!
Plate Movements-Icing on the
Cake Activity
A
Divergent
B
Convergent
C
Transform
•plates are
moving
apart
•plates are
coming
together
•plates are
slipping
past each
other
•crust is
returning
to the
mantle
•crust is
not created
or
destroyed
•new crust
is created
•Magma is
coming to
the surface
A
Divergent
Continental crust
 rift valley
B
Convergent
2 continental plates 
mountain range
C
Transform
Plates move
against each
other
Stress builds up
Oceanic crust  midocean ridge
2 oceanic plates or
oceanic + continental
subduction
Stress is released
earthquake
The Big Picture
Let’s Play
Mountains
Plates move apart
Volcanoes
Changes the shape of the ocean
floor
Causes Earthquakes
Plates collide
Two plates slide past one
another
One plate slides under another
When two plates
converge
________
magma may
work its way
through the
crust.
A ____________
is
volcano
formed when magma
breaks through to the
surface.
New _______
land is
formed when the
lava cools and
hardens.
An _______________
earthquake
occurs when plates move
and the crust slips or
breaks
past one
another.
Essential Question:
• What is sea floor
spreading?
Sea-Floor Spreading
 The mid-ocean ridge is the
longest chain of mountains on the
ocean floor.
 Most of the mountains in the midocean ridge lie hidden under
hundreds of meters of water.
 Hess proposed that the ocean
floors move, carrying the
continents along with them. The
movement begins at the midocean ridge.
 At the mid-ocean ridge, molten
material rises from the mantle and
erupts. This is called Sea Floor
Spreading.
Sea Floor Spreading
The process that continually adds
new material to the ocean floor is
called sea-floor spreading.
 The ocean floor plunges into deep
underwater canyons called deepocean trenches.
 Subduction is the process by which
the ocean floor sinks beneath a deepocean trench and back into the
mantle.
Ticket Out:
• 1. Most
volcanoes and earthquakes
are located where two ___________
________ meet.
• 2. The upper mantle and crust make
up the _______________.
 3. The ____________is a soft layer
that allows the lithosphere to float on
top of it.
Key Terms for Map
convergent boundary
divergent boundary
transform boundary
subduction
rift valley
mid-ocean ridge
continental crust
oceanic crust
mountain range
earthquake