Have you been aching for some ocean front
property? Just sit tight for several million years. You might get it.
As you know, the earth is continually changing. The outer layer of the
earth is called the crust. Under the continents, the crust is over 30
miles thick. Under the oceans, the crust is only about seven miles thick.
The crust is broken into chunks known as plates. The plates move about
on a fluid layer of the earth. Plates can move apart, come together, and
push past each other. When they do, tremendous things happen.
The mighty Himalayas
This
spectacular mountain range is the result of plates colliding. The 30-50
million years ago the continental plate that India is on came crashing
into the Eurasian plate. The crust pushed up forming the some of the tallest
mountains in the world. Mount Everest, in the Himalayas is 29, 028 feet
tall and still growing!
This pushing up of the land is called uplift.
It is one method of mountain building. You will learn others.
Try it!
Snickers,® Science This experiment
requires a Snickers® candy bar. It works best with a small, fun-sized
one, but you don't have to tell your folks that. This candy provides you
with a great and tasty model of Earth's structure and its plates.
Carefully unwrap and take out your Snickers®.
Bite off one end of your candy bar! Look closely
at the layers of the earth!
Chocolate - thin like Earth's crust
Caramel - fluid like the asthenosphere
(Earth's fluid layer)
Nougat - solid, representing the Earth's mantel
Core - sorry. Use your imagination here!
Gently
push your finger into the surface of your candy bar. Make sure that
you crack the chocolate layer.
The cracks your finger make represent Earth's plates.
Now it's time to play with your candy bar! Gently pull it apart.
Notice how the "plates" move on the caramel. Push it together.
Try to build your own little Mount Everest!
This is a Snickers® model of uplift.
One plate pushed into another buckling the bar.
Once you finish testing how the plates move, destroy
your evidence!
Earthquake!
Have you tried sliding a heavy box around? If you haven't,
you are really missing out. What usually happens is you are sliding along
just fine when you hit a little bump or ridge. You push harder and harder
until you conquer the bump. The box surges forward, much faster than before.
The box story is a simple example of how force builds
up and is released in an earthquake. An earthquake is a
shaking or trembling of the earth. Earthquakes happen at the edges or
boundaries of plates. The earth moves along cracks called faults.
If a fault builds up pressure, when the force is great enough it suddenly
releases. The result is violent shaking.
Do
it!
You can simulate your very own earthquake. You'll need ...
your two hands! Push your hands together with all your might. Try to slide
one toward you and the other away from you while you push. Eventually one
hand will win. There will be a tremendous release of pressure and your hands
will move apart. As long as you have all your lab supplies, simulate all
three types of faults at the right.
Pele, daughter of an island goddess named
Haumea, knew she was different. She was quick-tempered with red hair and
eyes. Her uncle, Lonomakua, was keeper of the flames. He knew Pele would
be an apt student. He taught her all his secrets of fire. Pele's sister,
Namaka was goddess of the water. She was jealous of Pele and forced Pele,
her bothers and other sisters out of their home. They traveled across
the sea to a new place called Hawaii.
But Hawaii already had its own god named Aila'au,
or forest eater. Pele and Aila'au fought for control of Kilauea.
They threw fireballs, erupted volcanoes and spewed smoke at each other.
When the smoke finally cleared, Pele had won. People of the Hawaii respected
Pele. Legend says that if you remove lava rock from the islands Pele will
curse you. She's there today you know, whenever Kilauea, Mauna Loa, or
Mauna Kea, the volcanoes of Hawaii, turn on the heat.
The Hawaiian Islands were created by volcanoes.
A volcano is an opening in the earth's crust where rock and steam come
out. The islands are located on a plate, which is moving northwest at
a rate of about four inches per year. The plate is passing over a "hot
spot" or volcanic vent. This vent has been spewing lava for millions
of years. The
vent spews lava and creates a volcanic island. The plate moves on. The
vent spews more lava, creates another island, and the plate moves on.
The evidence? The oldest islands are the northwestern ones - in the direction
the plate is moving.
Volcanic landforms
Shield Volcanoes
form from relatively quiet eruptions. The slides are gently sloping.
It doesn't really look like a classic volcano.
Cinder Cones have
a classic volcano shape. They are smaller than composite or stratovolcanoes
because their explosive eruption doesn't contain much material, and
that material is cinders.
Composite
Cones also have the classic volcano shape. They develop from
alternating explosive eruptions of cinders and quieter eruptions with
accompanying lava flow.
Calderas are rounded
depressions formed when the ground collapses from an explosive eruption.
This caldera filled with water forming Crater Lake.
Volcanic
Plateaus don't look like volcanic
landforms, but they are. They are flat-topped, and built of volcanic
flows. Remember the buttes from earlier in this unit? Their hard,
flat top is often volcanic material.
Quiz
time!
Read each question and answer it in your head.
Check your answer using the drop down menu option.
What volcanoes are created from alternating violent and calm
eruptions?
What mountain building force created the Hawaiian
Islands?
Which flat volcanoes indicate quite eruptions
and lava flows.
Crater Lake is actually one of these that filled
with water.
Who is the respected goddess of Hawaii's volcanoes?
Which volcanoes are composed of cinders rather
than lava flow.
Volcanoes are classified as active, dormant,
and extinct. Which would prove the least threat to us?
How do we know the Hawaiian plate is moving?
Build
a volcano 1
Materials:
Index card
Plastic zipper storage bag
Plaster of Paris
Food coloring
Water
Hair dryer
Procedure:
Mix about 1/2 cup of plaster of Paris with enough water to pancake
batter consistency.
Put a drop or two red food coloring in the mixture.
Spoon the mixture into the storage bag.
Clip a small hole in one corner of the bag.
Cut a small hole in the center of the index
card.
Slip the baggie through and squeeze a little
plaster through the hole.
Squeeze gently. Remember, shield volcanoes erupt
calmly and quietly.
Use the hair dryer to dry the first eruption.
Repeat the process.
You may have to cut the hole open again if "lava"
clogs it.
You can paint your resulting shield volcano.
Build a
volcano 2
Materials:
Film canister
Salt dough (1/2 c. salt, 2 c. flour, water)
Baking soda
Red food coloring
Vinegar
Paints
Plate
Procedure:
Construct a volcano out of salt dough on the plate.
You will want to create a classic composite
shape.
Insert the film canister in the center.
Let your composite volcano dry.
Paint the volcano if you would like.
When you are ready to cause it to erupt, go
outside.
Fill the film canister 1/2 full of vinegar.
Add a couple of drops of red food coloring and
1 tablespoon of baking soda.
Your "lava" will erupt and flow over
the sides of your volcano.
Cheater
Volcano
Materials:
1 warm bottle or can of soda
Procedure:
Go outside!
Shake the soda.
Open it up.
The soda explodes out of the can much like a volcanic
eruption. The contents of the can are under pressure. When the pressure
is released the contents rush out.
Get the plug-ins:
, and
(The QuickTime plug-in is needed to play sounds and movies correctly.)
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