Transcript What do you think

• 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
What We Know So Far
What We Want To Know
• What causes the plates to move?
• THE answer to this question we believe is:
convection currents in the mantle.
• animation
Convection
• 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
• 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
• Animation
• As the convection currents move through the
mantle, it causes the plates to move in the
lithosphere.
What do you see here?
• Plate Boundaries
Plate Boundaries
• 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
• Place where 2 plates come together, or
converge.
• Oceanic plate + Continental plate = subduction
• Continental plate + Continental plate =mountains
•
OptIPuter Outreach
Subduction at Trenches
• 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
•
Subduction Animation - Earthguide Online Classroom
Transform Boundary
• Place where two plates slip past each other in
opposite directions.
• Transform Boundaries = Earthquakes
•
•
Observe animations of processes that occur along plate boundaries.
animation
• land masses have slowly
moved over time
• Plates move on top of
asthenosphere
• Two plates slip past each
other in opposite directions
Matching Game
• Convergent boundary
• Sea-floor spreading
• Plate tectonics
• Happens at divergent
boundaries, allows magma to
rise to the ocean floor
• Continental drift
• Two plates collide with each
other
• Divergent boundary
• Two plates separate with
each other
• Transform boundary
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.