Plate TectonicsPlate Tectonics
Plate TectonicsPlate TectonicsPlate BoundariesPlate Boundaries
Causes of Plate TectonicsCauses of Plate Tectonics
Plate TectonicsPlate Tectonics
What is Plate TectonicsWhat is Plate Tectonics
• The Earth’s crust and upper mantle are broken into sections called plates
• Plates move around on top of the mantle like rafts
What is the What is the LithosphereLithosphere??
• The crust and part of the upper mantle = lithosphere–100 km thick –Less dense than the material
below it so it “floats”
What is the What is the AsthenoshereAsthenoshere??
• The plastic layer below the lithosphere = asthenosphere
• The plates of the lithosphere float on the asthenosphere
2 Types of Plates2 Types of Plates
• Ocean plates - plates below the oceans
• Continental plates - plates below the continents
Questions...Questions...• What is the theory of plate tectonics?
• What is the asthenosphere?• What is the connection between the
two?• What are the two types of plates?
Plate BoundariesPlate Boundaries
Plate BoundariesPlate Boundaries
• Divergent Boundary – moving • Convergent Boundary – moving • Transform Fault Boundary – moving
________________________
together
sideways past each other
Divergent BoundariesDivergent Boundaries
• Boundary between two plates that are moving apart or rifting
• RIFTING causes SEAFLOOR
SPREADING
Features of Divergent Features of Divergent BoundariesBoundaries
• Mid-ocean ridges• rift valleys• fissure volcanoes
• subduction zone called a TRENCH
Convergent BoundariesConvergent Boundaries
• Boundaries between two plates that are colliding
• There are 3 types…
Type 1Type 1• Ocean plate colliding with a less
dense continental plate
• Subduction Zone: less dense plate slides under the more dense plate
• VOLCANOES occur at subduction zones
Andes Mountains, Andes Mountains, South AmericaSouth America
Type 2Type 2• Ocean plate colliding with
another ocean plate
• VOLCANOES occur at subduction zones
Aleutian Islands, AlaskaAleutian Islands, Alaska
Type 3Type 3
• A continental plate colliding with another continental plate
• Have Collision Zones:–mountains form.
Transform Fault BoundariesTransform Fault Boundaries
• Boundary between two plates that are sliding past each other
• EARTHQUAKES along faults
San Andreas Fault, CASan Andreas Fault, CA
Questions...Questions...• What are the three types of
boundaries?• What direction do plates go for
each?• Which boundary has a subduction
zone…what occurs at a subduction zone?
Causes of Plate Causes of Plate TectonicsTectonics
What cause plates to move?What cause plates to move?
Convection Currents • Hot magma in the Earth moves
toward the surface, cools, then sinks again.
• Creates convection currents beneath the plates that cause the plates to move.
• The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH
• Subduction Zone: where the less dense plate slides under the more dense plate
• VOLCANOES occur at subduction zones
Explain Pangaea
• This is what type of boundary ?
What are the two types of plates?
Divergent plate boundaries move_______
Tectonic plates move only _______ per year
A. KilometersB. MilesC. CentimetersD. Millimeters
This type of plate movement can result in the formation of mountains and/or volcanoes
What is the lithosphere?
Two transformative plates slide past each other. What geological event is likely to occur?
Questions...Questions...
• How is a convection current formed?
• What are the three types of plate boundaries?
• What causes plates to move?
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