Download Plate Tectonics PowerPoint

2/26/2014
Explain CONVECTION in
your own words.
Today’s Goal:
I CAN explain what plate
tectonics is, what causes
it, and forms from it.
Today’s Plan
1. Finish continental drift questions
2. Special demonstration (reward
for students with finished work)
2. Vocabulary Practice
What are “Plates?”
The Earth’s Plates are
a lot like the cracked
shell of a hard boiled
egg.
Earth’s
LITHOSPHERE, its
solid outer shell, is
broken into pieces
separated by jagged
cracks.
How Plates Move
• Theory of Plate Tectonics:
Pieces of Earth’s Lithosphere are in slow, constant
motion, driven by convection currents in the
mantle.
This theory explains:
• The Formation,
• The Movement,
• And Subduction of Earth’s Plates
Plate Boundaries
• Three types of Plate Boundaries:
– DIVERGENT: Where two plates move APART.
-CONVERGENT: Where two plates come TOGETHER.
Plate Boundaries
• Types of Plate Boundaries:
– TRANSFORM: Where two plates slide past
each other, moving in opposite directions.
How the Plates Move
• The movement of convection currents in the
mantle is the major force that causes plate
motion.
Convection Currents
Convection: When a fluid is heated and
becomes less dense it rises, and when it cools
down it becomes more dense and sinks
Convection happens in the ASTHENOSPHERE
Let’s take a closer look at how this works:
COOL by crust
Heat gives
particles more
energy and
they spread
apart
becoming less
dense
Particles lose
energy, slow
down and
move together,
becoming
more dense
HEAT from core
Other contributors to plate movement
• Ridge Push: gravity pulls oceanic lithosphere
downhill, especially at mid-ocean ridges
Other contributors to plate movement
• Slab Pull: oceanic lithosphere is more dense
than hot asthenosphere, so the oceanic
lithosphere will sink when it meets the
asthenosphere
Other contributors to plate movement
• Subduction: when one plate goes under another
plate (part of slab pull at convergent boundary)
Vocabulary Practice
You need to write a definition AND draw/color a
picture for each of the following 8 words:
Pages 108-110 will help you. The picture should
be ¼ of page. (So this will take 2 pages)
•
•
•
•
•
•
Plate Tectonics
Divergent
Convergent
Transform
Convection
Ridge Push
• Slab Pull
• Subduction