Download Plate Tectonics

Plate Tectonics
Objective: describe the theory of plate
tectonics
Plate Tectonics
The crust is embedded into the lithosphere and
broken into plates
Plate Tectonics
Plate tectonics: continents are embedded
in lithospheric plates, as the lithosphere
moves on the asthenosphere, the
continents also move.
What makes plates move?
The heat of the mantle forms a process called
Convection.
As the magma in the mantle that is close to the
core heats up, it rises towards the surface of the
Earth.
When it gets near the surface it cools and sinks
back down again, gets re-heated and the process
repeats
Why do plates move?
This movement of magma into the
asthenosphere is what causes the lithosphere
and plates to move!
Develop a Theory
Come up with a theory to explain the
next 3 pieces of evidence…
Evidence #1
The continents look like they fit together.
Evidence #2
Some fossils are only found in isolated parts of the
world all the way across the oceans.
Evidence #3
Rock layers and structures match in continents
separated by the oceans.
What does this evidence support about how the world
looked 250 million years ago?
Why/What caused continents to move?
Continental Drift Theory
Continental drift theory is the movement of the continents
It states that 250 million years ago the continents were one
super continent and have since drifted apart
The super continent is called Pangaea
The Evidence:
While we cannot go back 250 million years and
observe the position of the continents (since we
don’t have a time machine), here is the evidence
that supports continental drift theory:
Evidence for continental drift
1.
The continents appear to fit together
2. Fossils of the same animals and plants are found
on different continents
3. Matching rock formations are found on different
continents
Stop!
Plate Boundaries
The edge of a plate where it meets another plate is
called a Plate Boundary
There are three things that can happen at plate
boundaries:
http://www.classzone.com/books/earth_science/terc/
content/visualizations/es0804/es0804page01.cfm?cha
pter_no=08
1: Plates can move apart- Divergent
Animation!
http://scign.jpl.nasa.gov/
learn/plate4.htm
Divergent:
This happens at Mid-ocean ridges, it causes the sea to get
wider. (Sea-Floor Spreading)
Causes earthquakes, volcanoes, rift valleys, ridges.
Ex: the Mid-Atlantic ridge, the East Pacific Rise
2: Plates can slide past each otherTransform
Transform:
Plates slide past each other
Causes earthquakes
Ex: San Andreas Fault, North Anatolian Fault
http://www.classzone.com/books/earth_science/t
erc/content/visualizations/es0804/es0804page01.c
fm?chapter_no=08
3) Plates move towards each otherConvergent
Three types of convergent boundariesa) Ocean-ocean subduction
b) Ocean-continent subduction
c) Continent-continent collision
Subduction means one plate diving under another plate
A: Ocean-ocean subduction
Occurs deep in the ocean.
Causes deep-sea trenches, earthquakes, volcanic island
arcs
Ex: Indonesian Islands
A: Ocean-ocean subduction
PICTURE!
B: Ocean-continent subduction
An oceanic plate dives under a continental plate
Causes deep-sea trenches along continents,
earthquakes, volcanoes on the edge of a continent
Ex: Western coast of South America
http://www.classzone.com/books/earth_science/terc/content/visualizations/e
s0804/es0804page01.cfm?chapter_no=08
B: Ocean-continent subduction
Picture!
C: Continent-Continent Collision
Two continents run in to each other.
Causes mountains to rise (mountain building),
earthquakes
Ex: Himalayas- India crashed in to Asia!
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0808/es0
808page01.cfm?chapter_no=08
C: Continent-Continent Collision
http://www.classzone.com/books/earth_science/terc/content/visualizations
/es0808/es0808page01.cfm?chapter_no=08
Questions (due Monday!):
Section review 8.2- pg 179
1: Explain how new oceanic crust is formed at a divergent boundary.
2: Describe two different types of subduction boundaries. Use the plate boundary map on
pages 712-713 to identify an example of each type.
3: Describe what happens at a collision boundary. Identify a collision boundary on the map on
pages 712-713.
4: Describe the movement of plates at a transform boundary, and give some examples.
5: What types of plate boundaries are not shown in the diagram on pages 174-175?
6: Critical Thinking: Explain how the densities of oceanic crust and continental crust
influence what happens when an oceanic plate converges with a continental plate.
7: Geography: In 2001, a large earthquake related to the movements of two plates occurred
about 20 kilometers northeast of Olympia, Washington. Use the map on pages 712-713 to
identify the plates and the type of boundary they share.