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Plate Tectonics
Liz LaRosa for use with my 5th Grade Science Class
http://www.middleschoolscience.com 2009
Earth’s Layers
The Earth's rocky
outer crust solidified
billions of years ago,
soon after the Earth
formed.
This crust is not a
solid shell; it is broken
up into huge, thick
plates that move atop
the soft, underlying
mantle.
Stop and Answer!
1. What are the 4 layers of the earth?
2. Put them in order from the outermost layer
to the innermost layer (from the outside to
the center).
Plate Tectonics
• The plates are pieces of the lithosphere that
move around.
Think About This:
Imagine you have a balloon. You cover the outside
of it in a layer of toothpaste. Then you get a piece
of paper and slide it around the surface of the
balloon. This is similar to how the continents
(land) moves around the Earth. Think of the
mantle as the toothpaste and the crust as the
paper.
Each plate has a name. They have drifted around
the Earth’s crust, but if you put them together,
they would fit like puzzle pieces.
Continental Drift
Alfred Wegener
hypothesized in the
1900’s that continents
were once a single land
mass that drifted apart.
Fossils of the same
plants and animals are
found on different
continents, providing
evidence (supportive
data or proof) of the fact
that all of the
continents may have
once been one big
continent!
He called this supercontinent Pangea, a Greek
word for “all Earth,” and said it probably existed
about 245 Million years ago.
Evidence of Pangea: Look at all of the places
that the same fossils have been found!
Stop and Answer!
1. Why might finding the same fossils of the
same animals in different continents be proof
that the continents used to be part of the
same land mass? Explain your answer in
complete thoughts and complete sentences.
How do the plates move?
• Earth’s mantle transfers
heat through convection
currents.
• **Remember!**
Convection is when heat
energy is transferred in a
fluid. Warm objects or
locations move to cooler
objects or locations in
circular patterns.
The mantle is made up of
solids and liquids.
The top part of the mantle,
near the crust is cooler.
What happens to cooler
particles?
They get more dense (closer
together).
Dense objects sink through
less dense objects.
(Remember, that’s why
icebergs float)
The rocks closer to the core
are melted. They have more
energy, so the spread farther
apart and float to the top.
The mantle is constantly
moving in convection
currents.
What happens when the plates
move?
Earthquakes!!
What causes earthquakes?
• Tectonic plates move past each other causing
stress. Stress causes the rock to deform.
Stress
• Sometimes the rocks in the plates
stick together. As the plates continue
to move, the rocks get stressed.
• When the rocks break free, the
stress is released in a big shake
that we feel as an earthquake.
Earthquakes
San Francisco Earthquake 1910
• Earthquakes are a
sudden shaking of the
ground caused by the
movement of plates.
• Earthquakes occur
along faults.
– Faults are cracks in
the crust where
plates move past
each other.
Types of Faults
• Along the boundary
separating any two
Divergent:
plates, the relative
Pulling
motion between the
plates can be
Convergent:
classified into one of
Pushing
3 categories
Transform:
Sliding
Stop and Answer!
• Imagine that you live on a fault line. One day,
there is a huge earthquake! You step outside
and find that the swing set that used to be in
your backyard is now 20 feet away in your
neighbor’s yard.
1. What kind of fault line do you probably live
on? (You can use the slide before this for
reference.) Explain your reasoning.
Divergent Boundary – when two tectonic plates move
away from each other.
Arabian and African Plates are on a divergent boundary.
When this happens often bodies of water form, because
water fills in the area where land used to be.
Convergent Boundary – when two tectonic plates move
toward each other. The Indian and Eurasian Plates
are on a convergent boundary..
Time to investigate!
1. Logon to Discovery Education.
2. Click on the assignment that says “Tectonic Forces”
3. Click “Start Here” at the bottom of the screen and listen to
the information. Then, close out that window.
4. Click a boundary from the box that says “Choose a type of
boundary” at the top of the screen.
5. Click the white circles to see what kind of tectonic activity
and geographic features go together.
6. Read the background information by clicking the
“Background” tab at the bottom of the screen.
7. Answer the questions from the “Questions” tab in your
notebook.