Download Plate Tectonic Theory

5 minute check
October 7, 2013
What are the layers of the Earth?
What is one fact about each layer?
http://www.cnn.com/2012/10/01/tech/mantle-earth-drillmission/index.html
3.1 - The student will describe the characteristics of the
layers of the earth.
Listen to songhttp://www.flocabulary.com/geology/
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Let’s watch Bill Nye The science guy video
Earth’s Crust
While watching the video I want you to fill in
the Earth’s Crust Quiz
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What is “Pangaea” (whole earth)?
5 minute check
October 8, 2013
What is “Pangaea” (whole earth)?
3.1 - The student will describe the characteristics of
the layers of the earth.
Evidence for
Plate Tectonics
•
Alfred Wegener in the early
1900’s proposed the hypothesis
that continents were once joined
together in a single large land
mass or super continent he
called Pangea (meaning “all
land” in Greek).
•
He proposed that Pangea had
split apart and the continents
had moved gradually to their
present positions - a process that
became known as continental
drift.
According to the hypothesis of
continental drift, continents
have moved slowly to their
current locations.
Pangaea about 200 million years ago, before it began breaking up.
Wegener named the southern portion of Pangaea Gondwana, and
the northern portion Laurasia.
The continents about 70 million years ago. Notice that the
breakup of Pangea formed the Atlantic Ocean. India’s eventual
collision with Eurasia would form the Himalayan Mountains.
The position of the continents today. The continents are still
slowly moving, at about the speed your fingernails grow. Satellite
measurements have confirmed that every year the Atlantic Ocean
gets a few inches wider!
Continents fit together
like a puzzle….e.g. the
Atlantic coastlines of
Africa and South
America.
The Best fit includes the
continental shelves (the
continental edges under
water.)
Picture from
http://www.sci.csuhayward.edu/~lstrayer/geol2101/2101_Ch19_03.pd
Picture from
http://volcano.und.e
du/vwdocs/vwlesson
s/plate_tectonics/par
t3.html
Fossils of plants and animals of the
same species found on different
continents.
This hypothesis helped to explain why fossils of
plants and animals, along with matching rocks (strata),
have been found on both sides of the Atlantic Ocean.
Example: Applachain Mountains
And if the continents are put back to
their pre-drift locations the mountains
form a continuous chain.
Lystrosaurus - fossils of this little land reptile were found in Africa,
India, Argentina, China and Antarctica!
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Rock sequences (meaning
he looked at the order of
rock layers) in South
America, Africa, India,
Antarctica, and Australia
show remarkable
similarities.
Wegener showed that the
same three layers occur at
each of these places.
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Picture from
http://volcano.und.edu/vwdocs/vwlessons/plate_tectonic
s/part4.html
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Everyone agreed that Wegener’s evidence
was compelling. But wouldn’t we feel the
movement?
Also, wouldn’t there be evidence to show
that the continents were still moving today?
Wegener was a meteorologist and his theory
was not well accepted. (He died on an
expedition in Greenland collecting ice
samples)
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One reason scientists had
a hard time with
Wegener’s theory is that
there was no mechanism
for the continents
motion.
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Picture from USGS
http://pubs.usgs.gov/gip/dynamic/HHH.html
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In the 1960’s, a scientist
named Henry Hess made a
discovery that would
vindicate Wegner.
Using new technology,
radar, he discovered that
the seafloor has both
trenches and mid-ocean
ridges.
Harry Hess proposed the
sea-floor spreading theory.
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Hess proposed that hot,
less dense material below
Earth’s crust rises toward
the surface at the midocean ridges.
Then, it flows sideways,
carrying the seafloor
away from the ridge in
both directions.
Picture from http://library.thinkquest.org/17457/platetectonics/4.php
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As the seafloor spreads apart at a midocean ridge, new seafloor is created.
The older seafloor moves away from the
ridge in opposite directions.
This helped explain how the crust could
move—something that the continental
drift hypothesis could not do.
Picture from
http://www.pbs.org/wgbh/aso/tryit/tectonics/divergent.html
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In 1968, scientists aboard the research ship
Glomar Challenger began gathering
information about the rocks on the seafloor.
Scientists found that the youngest rocks are
located at the mid-ocean ridges.
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Seafloor Spreading
provided insight to the
mechanism for how the
continents moved.
The magma which pushes
up at the mid-ocean ridge
provides the new land
pushing the plates, and the
subduction zones gobble
up the land on the the
other side of the plates.
The mechanism was
convection currents!
Picture from
http://library.thinkquest.org/17457/platetectonics/2.ph
p
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Both Hess’s discovery and
Wegner’s continental drift
theory combined into what
scientists now call the Plate
Tectonic Theory.
Theory of plate tectonics:
• The Earth’s crust and part of the
upper mantle are broken into
sections, called plates which move
on a plastic-like layer of the mantle
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Plate Tectonics explains
◦ Earthquakes
◦ Mountains
◦ Volcanoes
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Closing:
What is continental drift?
5 minute check
October 9, 2013
What is continental drift?
3.1 - The student will describe the characteristics
of the layers of the earth.

Alfred Wegener hypothesized what?
Supercontinent called Pangaea
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What evidence did he use?
Similarities in the types of rocks and ancient
fossils
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In the 1960s scientists discovered what about the
sea floor?
Between the crust and the mantle there were all
cracks and each piece they called plates. They
called the moving of these plates Plate Tectonics.
They are in constant motion and if there is a
continent on the plate then it too is moving.
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We are going to watch a video on sea floor
spreading
video
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First thing we have to understand that in the
Asthenosphere there are convection currents.
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But why do we have convection currents in
the Asthenosphere???
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Well the first thing we have to understand is
that heat can travel three different ways
Example
YUP 3!!!!
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By convection!
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Let’s see an example of what convection is
example we will need cold water and warm
water
Students have a try at it, example
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Fill the large beaker to EXACTLY 300ml, place in middle of draw
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In the small beaker fill close to the top, but not so high that you
cannot walk while holding it
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Add EXACTLY 3 drops of food coloring to your SMALL beaker and stir
with straw calmly till mixed
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Bring your small beaker to the microwave and heat water for 30
seconds. Using a paper towel to hold the small beaker walk calmly
back to your group.
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Place a piece of tin foil TIGHTLY on your small beaker and drop it
gently into the lager beaker carefully! Try not to spill!
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Using your straw poke A (meaning 1) hole in your aluminum foil to
let small beaker water out into big beaker.
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Watch to see convection currents occur
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Clean and dry all materials before you return them to the counter
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What is convection heat?
5 minute check
October 10, 2013
What is convection heat?
3.1 - The student will describe the characteristics
of the layers of the earth.
Now that we know why they move lets learn
about the different movements plates can make
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An example is seafloor spreading
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Plates are separating from each other as a new land mass forms
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This is seen at mid-ocean ridges and rifts
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Plate separation is a slow process. For example, divergence
along the Mid Atlantic ridge causes the Atlantic Ocean to widen
at only about 2 centimeters per year.
Even though most are under the sea, not all of them are, when
two continental crusts begins to separate the stretched crust
forms a long, narrow depression called rift valley. A rift valley is
currently forming in East Africa, and might eventually be new
ocean basin.
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Two continental
plates collide. &
crumple the edges of
the plates & form
mountains.
We can see the end result of
the collision between the
Indian & Eurasian plates
which are the Himalayan
Mountains.
Picture from www.geology.com Author Hobart M. King
Picture from USGS
collision
Three types of convergent boundaries:
Continental-Continental
Oceanic-Continental
Oceanic-Oceanic
destruction
Produces a subduction zone, where the lithosphere is sliding back into
the mantle.
What type of convergent boundaries are these?
a. Continental-Oceanic
______________
Oceanic-Oceanic
b. _______________
c. Continental-Continental
_______________
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When an oceanic plate goes
underneath or is subducted
under a continental plate it is
called subduction.
This forms a trench, or deep
valley, where the plates meet.
An example of a subduction
zone is the Marianas Trench
where the Pacific Plate is
subducting under the Eurasian
Plate.
Subduction is another type of a
convergent plate movement.
Picture from www.geology.com Author Hobart M. King
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Two plates slide past
each other
At transform
boundaries crust is
only deformed or
fractured.
◦ Example: San Andreas
Fault in California
A
Divergent
•plates are
moving apart
•new crust is
created
•Magma is coming
to the surface
B
Convergent
•plates are coming
together
•crust is returning
to the mantle
C
Transform
•plates are
slipping past each
other
•crust is not
created or
destroyed
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
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Fault: a crack or fracture in the Earth’s crust
along which movement, dislocation and
overlaps of plates occur.
Plate Boundary: Where two or more plates
meet
Divergent
Convergent
Transform
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Closing:
What are the three main types of plate
movements?
5 minute check
October 11, 2013
What are the three main types of
plate movements?
Video
3.1 - The student will describe the characteristics of
the layers of the earth.

Friday Quiz
A
Divergent
•plates are
moving apart
•new crust is
created
•Magma is coming
to the surface
B
Convergent
•plates are coming
together
•crust is returning
to the mantle
C
Transform
•plates are
slipping past each
other
•crust is not
created or
destroyed
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
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Fault: a crack or fracture in the Earth’s crust
along which movement, dislocation and
overlaps of plates occur.
Plate Boundary: Where two or more plates
meet
Divergent
Convergent
Transform