Transcript 7.3 Theory of Plate Tectonics

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Get out your lab and your Ch. 7 Section 3 Notes and on your small
paper answer the following question:
What do you think is the driving force that causes the Earth’s
tectonic plates to move?
Today’s Schedule
1. Ch. 7 Section 3 Notes/Discussion
2. Review Sea-Floor Spreading Lab
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What We Know So Far
What We Want To Know
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What causes the plates to move?
THE answer to this question we believe is:
convection currents in the mantle.
animation
Convection
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Convection- heat transfer by the movement of
currents within a fluid
Caused by differences of temp. and density within
the fluid
Convection Currents in Earth
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1. What is the heat source?
2. What is flowing?
Heat from the core and the mantle itself causes
convection currents in the mantle.
Google Image Result for http://www.windows.ucar.edu/earth/interior/e_thermal_history_animated.gif
Convection Currents in the Earth
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Animation
As the convection currents move through the
mantle, it causes the plates to move in the
lithosphere.
What do you see here?
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Plate Boundaries
Welcome to Science 9/21
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Get out the Ch. 7 Section 3 Notes
Today’s Schedule
1. Question of the Day
2. Experiment of the Day
3. Finish Notes/Discussion
4. Plate Tectonics Computer Activity
Question of the Day
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A decrease in the amount of sea otters can lead to
an increase in sea urchins. An increase in the sea
urchin population results in less kelp. Kelp
provides fish with protection from predators. What
does this chain of events demonstrate?
A. living things grow
B. living things depend on only other living things
C. living things depend on other living and
nonliving things
D. living things do not depend on each other
Plate Boundaries
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Divergent Boundary- place where 2 plates move
apart or diverge.
Most DB’s are at mid-ocean ridges.
On land DB’s form deep valleys called rift valleys
Fig. 19.21 - Evolution of a Divergent Plate Boundary
animation
Convergent Boundary
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Place where 2 plates come together, or converge.
Oceanic plate + Continental plate = subduction
Continental plate + Continental plate =mountains
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OptIPuter Outreach
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Subduction at Trenches
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Deep-ocean trench- underwater canyon where
ocean crust sinks into the mantle.
Subduction- process by which ocean crust sinks
beneath a deep-ocean trench and back into the
mantle
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Subduction Animation - Earthguide Online Classroom
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Transform Boundary
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Place where two plates slip past each other in
opposite directions.
Transform Boundaries = Earthquakes
Observe animations of processes that occur along plate boundaries.
animation
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Matching Game
land masses have slowly
moved over time
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Convergent boundary
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Sea-floor spreading
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Plate tectonics
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Continental drift
Two plates collide with each
other
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Divergent boundary
Two plates separate with each
other
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Transform boundary
Plates move on top of
asthenosphere
Two plates slip past each other
in opposite directions
Happens at divergent
boundaries, allows magma to
rise to the ocean floor
Transform
Plate Boundaries Contest
Convergent
Divergent
Ch. 7 Section 3 The Theory of Plate
Tectonics
Things you should know: what plates are,
directions plates move, and some landforms that
plate movement creates.
Now, you need to figure out what causes the plates
to move.
Observe these demonstrations to discover the
answer.