Download Plate boundaries presentation

Plate
Boundaries
Presented by Kesler Science
Essential Questions:
1. What is plate tectonics?
2. What are the three types of plate boundaries?
3. What crustal features are formed at plate
boundaries?
Quick Action – INB Template
1.
Cut out the INB Template.
Paste it into your
notebook.
2.
The next two pages will go
on top of this page to
make a 3 page flip book.
3.
This Template is page 3.
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KeslerScience.com
Quick Action – INB Template
Page 1
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Page 2
Plate Boundaries
Seven Continents today
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Plate Boundaries
Sea-Floor Spreading
Harry Hess discovered that magma was
rising on the sea floor causing it to spread.
The hot magma rising in the mantle caused
the spreading on the sea floor and the
large pieces of crust (tectonic plates) to
move.
Theory of Plate Tectonics
These two theories lead to the Theory of Plate
Tectonics.
Continental Drift Theory
Alfred Wegener
developed the theory that
the continents drift. At the
time he did not know the
mechanism that made this
happen.
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Plate Boundaries
Plate Tectonics is the theory that Earth's outer crust
(lithosphere) is divided into several plates that glide over
the less rigid asthenosphere (upper mantle).
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Plate Boundaries
What is the engine that
moves the plates?
Convection Currents
• Transfers energy in the
mantle
• Causes the hotter magma
in the mantle to rise
• Causes the cooler magma
in the mantle to sink
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Plate Boundaries
Continental Crust
• Layer of rock which forms the
continents
• Also forms shallow sea beds close to
shore (continental shelf)
• Floats on top part of the mantle
(asthenosphere)
• Older than oceanic crust, mostly
granite rock
• Thicker and less dense than oceanic
crust
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Plate Boundaries
Oceanic Crust
• A thin layer of crust that
underlies the ocean
basins.
• Consists mainly of basalt.
• Younger than continental
crust.
• More dense than
continental crust.
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Quick Action – Plate Boundaries
Let’s review the properties of continental and oceanic crusts. Make a T-chart
on your paper and list the characteristics of each type of crust under the
correct heading.
Continental Crust
Oceanic Crust
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Quick Action – INB Template
Type of
Boundary
Complete
the table as
you move
through the
PowerPoint
Presentation.
Glue into
your
notebook as
a reference.
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KeslerScience.com
Sketch of Boundary
Direction of Movement
Description/Features of Plate
Boundary
Examples
Ocean-Ocean
Ocean-Ocean
Ocean-Ocean
Ocean-Ocean
Ocean-Continent
Ocean-Continent
Ocean-Continent
Ocean-Continent
Divergent
Plate
Boundary
Transform
Plate
Boundary
Convergent
Plate
Boundary
Collision
Convergent
Plate
Boundary
Subduction
Plate Boundaries
What happens at plate
boundaries?
Plates do one of 3 things.
1. Converge (colliding or
coming together)
2. Diverge (dividing or
moving apart)
3. Transform (sliding past
each other)
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Converge
(destroys
crust)
Diverge
(creates
crust)
Transform
(neither destroys or creates
crust)
Quick Action – Plate Boundaries
Ready for a song? The melody is to the “Adam’s Family.”
Converging is colliding,
Diverging is dividing,
Transform is sliding,
We are the plate boundaries.
Dah na na na. <Snap, Snap>
Bet you can’t get that out of your head!
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Plate Boundaries
Divergent boundaries – dividing or moving apart
• Two oceanic crusts diverge and create a mid-ocean ridge (mountains under the
ocean).
• This process is call sea-floor spreading.
• New crust is created.
https://www.youtube.com/watch?v=ZzvDlP6xd9o
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The MidAtlantic
Ridge
actually
comes
above the
ground in
Iceland.
Plate Boundaries
Divergent boundaries – dividing or
moving apart
• Two continental crusts diverge and
create a rift valley.
• New crust is created.
• Example is the Great Rift Valley in Africa
• Over millions of years water will
eventually fill the valley.
https://www.youtube.com/watch?v=w7Y2R4KBwvo
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Plate Boundaries
Transform boundaries
• Plates slip sideways past each
other creating earthquakes.
• Crust is neither created or
destroyed.
• Many of these boundaries are
found on the sea floor.
• The most famous transform
boundary is the San Andreas fault
in California.
https://www.youtube.com/watch?v=ZxPTLmg0ZCw
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Plate Boundaries
What happens when plates
converge or collide?
• Continental/Continental =
folded mountains (Himalayas).
• Continental/Oceanic =
volcanoes form (Cascades in
Oregon and Washington)
• Oceanic/Oceanic = Volcanic
arc of islands form(Aleutian
Islands in Alaska)
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Plate Boundaries
Converging boundary -continental/continental boundary.
• Two continental crusts collide and push against each other.
• This pressure causes both plates to rise creating folded mountains.
• Not a subduction zone
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Himalaya
Mountains
Plate Boundaries
Converging boundary - continental/oceanic boundary
•
•
•
•
The ocean crusts goes below the continental crust because its more dense.
Volcanoes form on the continent.
A trench forms at the place when the plates collide.
Subduction zone
Cascade
Volcanoes in WA,
OR and CA
Old crust is destroyed
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Plate Boundaries
Converging boundary - oceanic/oceanic boundary
• Two oceanic crusts collide and push against each other.
• The older crust goes below the other one and creates a volcanic arc of islands.
• Subduction zone
Old crust is destroyed
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Aleutian
Islands in
Alaska
Quick Action – INB Template
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Quick Action – Plate Boundaries
Let’s review the three types of plate boundaries.
•
Get with a partner and get a white board
•
Decided which type of boundary you want to “act out.”
•
Demonstrate to the class your “boundary” and have the
class determine which type of boundary you are
representing by holding up the corresponding letter, which
represents converging, diverging and transform boundaries.
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KeslerScience.com
Plate Boundaries
Ring of Fire
•
•
•
•
A long chain of volcanoes
that surround the Pacific
Ocean.
One of the most geologically
active area on Earth.
Site of frequent earthquakes
and volcanic eruptions.
Caused by plate boundaries
converging, diverging and
transforming.
https://www.youtube.com/watch?v=KqrpkgKD5ko
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KeslerScience.com
Check for Understanding
Can you…
1.
Explain plate tectonics?
2.
Name the three types of plate boundaries and
describe their movement?
3.
Relate plate boundaries to the formation of crustal
features: such as mountains, trenches, volcanoes
and ridges?
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KeslerScience.com