Download mountains so high? - Discovery Education

WHY ARE THE
MOUNTAINS SO
HIGH?
An Introduction to Mountains
and Mountain Building
1 videocassette . . . . . . . . . . . . . . . 23 minutes
Copyright MCMXCV
Rainbow Educational Media
4540 Preslyn Drive
Raleigh, NC 27616-3177
Distributed by:
United Learning
1560 Sherman Ave., Suite 100
Evanston, IL. 60201
800-323-9084
www.unitedlearning.com |
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PRINCIPAL CREDITS
Producer, Writer and Director:
Peter Matulavich
Consultants:
Jim Mori, Ph.D. Scientist
in Charge United States
Geological Survey
Michael Worosz, M.A.
Curriculum Consultant
Peter Matulavich
Videography & Animation:
Diann Fried
Associate Producer:
Roxanne Hall
Production Manager:
United States Geological
Survey National
Geophysical Data
Center
KTVU
Volcano National Park
Stephen Harris, Ph.D.
Cascade Volcano
Observatory Mt. Rainier
National Park
Special Thanks to:
Video and Teacher's Guide produced for
Rainbow Educational Media
by Peter Matulavich Productions
San Dimas, California
TABLE OF CONTENTS
Introduction
1
Objectives
2
Summary
3
Review Questions
6
Discussion Questions
9
Activities
12
Glossary
14
Bibliography
16
Script
19
INTRODUCTION
This video is designed to introduce students to the subject of
mountains and mountain building.
Mountains have always captivated our imaginations but it has
been only in recent years that scientists have discovered the
mechanism behind mountain building: the slow-moving
tectonic plates which compose our planet's shell.
Students will learn through exciting, full-motion animation that
the earth's plates move as a result of movement in the material
that makes up the earth's mantle. Plate movement is
responsible for continental drift, earthquakes, volcanic
eruptions, and mountain building.
Mountains are formed in different ways. When two plates
squeeze against each other it causes the earth's crust to bend in
a series of folds we call folded mountains. Volcanic mountains
are formed when one plates dives beneath another, causing
magma to rise to the surface, where it cools and hardens into
rock. Fault-block mountains are formed when plate movement
causes sections of the earth's crust to snap and rise up on end.
Regardless of how they are formed, mountains are among the
most beautiful places on earth and provide us with many
natural resources, as well as retreats from the stresses of
modern living.
OBJECTIVES
After viewing this video, students should know:
• the name of the earth's interior layers
• the name of Alfred Wegener's supercontinent
• the cause of plate movement
• the three types of plate boundaries
• how folded mountains are made
• how fault-block mountains are made
• how volcanic mountains are made
• how hot spot volcanoes are made
• some natural resources found in mountains
• the recreational importance of mountains
SUMMARY
The video opens on some of the world's most majestic
mountains. After a montage of beautiful mountain scenics, the
narrator poses the questions: Why are there mountains in
some places on earth, but not in others? How are mountains
created? Why are the mountains so high?
Next, we see students pointing out mountain ranges on a large
globe. The narrator explains that while a globe is useful for
locating mountains, it can't tell us how mountains are made.
To understand that we have to look deep inside the earth.
Full-motion animation then reveals the various layers of the
earth's interior: the inner core; the outer core; the mantle; and
the earth's outer shell, which consists of the crust and the
rigid, outer portion of the earth's mantle.
Students learn that the earth's shell is cracked into more than a
dozen pieces called plates, and that each plate carries a
continent or an ocean basin, or sometimes both. The positions
of these plates are only temporary. They are moving at an
average rate of one to four inches a year in a variety of
directions, carrying continents and ocean basins with them.
Animation reveals what the continents looked like millions of
years ago and how they slowly reached their present-day
positions. Animation also shows what the world will look
like millions of years in the future as the continents continue
their slow dance around the globe.
The video then discusses what causes the plates to move: the
circulating movement of magma within the earth's mantle.
Students learn than in some places, plates are moving apart.
In other places, plates slide past each other. And in other
places, plates collide head-on. The area where
plates collide head-on is called a convergent boundary. Most of
the world's greatest mountain ranges occur near convergent
boundaries.
Next, animation reveals what happens when plates collide
head-on. Under the incredible pressure, layers of the earth's
surface are compressed and folded, rising high into the air,
forming folded mountains.
Students are featured making their own folded mountains by
laying out hand towels on a desk top and bringing the edges
together until the towels fold like sections of the earth's crust.
The world's highest mountains are made in much the same
way.
Students will learnthat some large mountains are actually
volcanoes, as the video segues to scenes of the 1980 Mt. St.
Helens eruption. Animation reveals how most of the world's
volcanoes are made, near subduction zones, as one plate dives
beneath another, causing liquefied rock to rise through the
earth's crust and erupt as lava.
Dramatic scenes of eruptions on Hawaii introduce students to
hot spot volcanoes, which form above a so-called hot spot in
the earth's mantle. Students will see how hot spot volcanoes
don't erupt with the explosive force of volcanoes like Mt. St.
Helens, but rather in showy displays.
A third type of mountain is the fault-block, and animation
clearly illustrates that this mountain is made when surface
faults snap, causing a section of crust to rise up on end.
Mountains are among the most beautiful places on earth as
the video's montage of mountain scenes depicts.
Students will learn that mountains are important for a variety of
reasons. They provide some of the last remaining habitat for
animals and provide people with a place to ease modern
stresses. Mountains are also important because of their many
natural resources. Finally, mountains teach us about the past,
and how our earth is constantly changing.
REVIEW QUESTIONS
1. What are the earth's interior layers?
The earth's interior layers consist of the inner
core, the outer core, the mantle, and the shell.
2. What composes the shell?
The shell is composed of the crust and upper
portion of the mantle.
3. The shell is broken into more than a dozen
pieces. What are these pieces called?
They are called plates.
4.
What causes the earth's plates to move?
The earth's plates move from the movement of
magma within the mantle.
5. What was the name of Alfred Wegener's
supercontinent?
It was called Pangaea.
6. What occurs at the three types of plate
boundaries?
The plates move apart, the plates come together and
the plates slide past each other.
7. How are mountains made at a convergent
boundary?
At a convergent boundary, the plates squeeze
together and the earth's crust is folded into
mountains.
8. How are volcanoes made at subduction
zones?
As one plate slides beneath the other, it causes
liquefied rock to rise through the earth's crust and
erupt as lava.
9.
How do volcanoes near subduction zones
typically erupt?
Volcanoes near subduction zones typically erupt with
explosive force.
10. What are hot spot volcanoes?
They are volcanoes that occur above hot spots in the
earth's mantle.
11. How do hot spot volcanoes typically erupt?
Hot spot volcanoes often erupt with showy displays of
lava fountains.
12. What type of zone does Mt. St. Helens occur
above?
Mt. St. Helens occurs above a subduction zone
13. How can you identify a volcano when it is not
erupting?
Many volcanoes have symmetrical sides.
14. How are fault-block mountains made?
Fault-block mountains are made as a section of crust
rises up on end.
15. Name some natural resources found in
mountains?
Answers include lumber, water, minerals and ores.
16. What is the climate at the top of the
world's highest mountains?
It is winter year round at the top of the world's
highest mountains.
17. How does vegetation change the higher you
go up a mountain?
As you go higher up a mountain, the dense forests
disappear and there are fewer species of plant life.
These questions are designed to
encourage classroom discussion
1. The video discusses how the earth's interior
consists of different layers.
Since we cannot see what is inside the earth, what
techniques do you suppose scientists use to determine
what is there?
Answers include drilling (limited to the crust), examining
lava, and seismic testing which renders images of the
earth's interior, not unlike the way radar and sonar render
images.
Why is drilling not an effective technique for
analyzing the earth's interior?
While drilling is useful at shallow depths, drills are
unable to penetrate more that a few miles into the crust.
2. Mountain building is discussed in the video.
Are the world's mountains increasing or decreasing in
size?
The world's youngest mountains are increasing in size as
the amount of growth (a couple of inches a year on
average) exceeds the amount of erosion. Older
mountains are no longer growing and are gradually being
worn away.
3. Most of the mountains featured in the video are
young mountains and were selected for their
impressive contours and peaks.
Can you name some young and old mountain ranges in
the United States?
Virtually all mountains in the western United States are
young mountains, having been formed in the last 20
million years. Virtually all mountains in the eastern
United States are old mountains, having been formed
over 200 million years ago. Young mountains can be
identified by their towering, jagged peaks. Old
mountains are not nearly so high, and their contours are
more rounded than jagged.
4. Folded, fault-block and volcanic mountains are
mentioned in the video.
Name some mountains close to you. Are they folded,
fault-block, or volcanic?
Answers vary with locality. The Appalachians and
Adirondacks and most eastern mountains are ancient
folded mountains. The Sierra Nevada, Tetons and many
other western mountains are fault-block. The Rockies
have features of both types. The Cascade range of the
Pacific Northwest are volcanic mountains.
5. The video discusses how a hot spot exists under
Hawaii.
Can you name an area in the United States that is
situated above a hot spot?
Yellowstone National Park is famous for its geysers, hot
springs and other geothermal features.
6. The video shows tons of ash pouring out of Mt.
St. Helens.
How might volcanic eruptions affect worldwide
weather?
10
Large eruptions can spew enormous amounts of ash and
debris into the atmosphere, where it can circle the globe,
block out the sun, and lower temperatures worldwide.
7. Mountains are often the focus of political and
environmental conflict. Some people want to
preserve the natural beauty of mountains and
want to restrict development, logging, mining
and certain recreational activities like mountain
biking and pack train trips. Other people feel
that mountains should be fully utilized for their
natural resources. Both sides present strong
arguments.
How should mountains be utilized in the future?
Answers vary with individual views.
11
ACTIVITIES
These activities are designed to encourage
students to learn more about some of the
things covered in the video.
1. The video shows the earth's interior layers.
Activity: Have students draw and color a crosssectional view of the earth showing the different
interior layers.
2. The video shows how the continents were once
joined in a supercontinent, called Pangaea.
Activity: Have students cut out shapes of the world's
continents and, by matching shorelines, position them
as they might have been positioned in the past.
3. The video explains that plate movement is
caused by circulating movement in the mantle.
Activity: This can be demonstrated by having students,
under supervision, boil rice, observing the circulating
movement of the rice as the water comes to a boil.
4. The video features several volcanic
eruptions.
Activity: Students can make their own erupting
volcanoes by first constructing a volcano out of papiermache, plaster of Paris, clay, or other material, making
sure to include a vent. Next, pour about 1/4 cup of
baking soda into the vent, followed by a similar amount
of vinegar. The baking soda reacts with the vinegar,
producing a foam which simulates lava during an
eruption.
12
5. The video shows how magma chambers can
fill with magma, causing a volcano to bulge.
Activity: This can be simulated by having students lay
an uninflated balloon near the edge of a table top and
then cover it with dirt. When the balloon is inflated it
causes the dirt to rise.
6.
The video discusses how folded mountains are
made when the earth's crust is squeezed
together.
Activity: This can be mimicked by having students lay
out a hand towel and then slide the edges together until
the towel rises up in folds.
7. The video concludes by showing the many
things to be found in the mountains.
Activity: Have students research and report to the class
on one or more aspects of mountains, e.g. mountain
recreation, plant and animal life, resources, ecology,
etc.
13
GLOSSARY
aqueduct: a large pipe or channel for bringing water from a
distant place
circulating: moving in a circle
compressed: pressed together
convection current: motion in a liquid or gas, caused by
heat
convergent boundary: boundary where two plates come
together
crater: a large depression formed by a volcanic eruption
crust: thin outermost layer of the earth debris: remains of
anything destroyed
divergent boundary: boundary where two plates move apart
erosion: process by which the surface of the earth is worn
away
erupt: burst forth
fault: crack in a rock, one or both sides of which have moved
in relationship to the other
fault-block mountain: mountain formed by the uplifting of
surface faults
folded mountain: mountain formed by the bending of the
earth's crust
fossil: hardened remains of a plant or animal
14
hot spot: area, far from plate boundaries, where magma has
surfaced
inner core: solid innermost layer of the earth
lava: molten rock that erupts from the earth
magma: name for lava before it reaches the earth's surface
magma chamber: reservoir of magma located in the
earth's crust
mantle: mostly molten layer of the earth, located below the
crust
ore: rock that contains metal
outer core: molten layer of earth located below the mantle
Pangaea: name for the supercontinent thought to have
existed millions of years ago
plates: rigid moving pieces of the earth's shell seismic
wave: shock wave caused by an earthquake
shell: outermost layer of the earth, including the crust and
outer portion of the mantle
subduction: process where one plate descends beneath
another
symmetrical: characterized by having matching parts
transform boundary: boundary where two plates slide past
each other
tectonic plates: rigid moving sections of the lithosphere
15
BIBLIOGRAPHY
Ballard, Robert D. Exploring Our Living Planet.
National Geographic Society, Washington, D.C.,
1983.
Bernstein, Leonard and Wong, Harry K. Earth Science,
2nded. Globe Book Co., New Jersey, 1979.
Calder, Nigel. The Restless Earth. Viking Press, 1972.
Cattermole, Peter and Moore, Patrick. The Story of the
Earth. Cambridge Univ. Press, 1985.
Clark, John. Earthquakes to Volcanoes. Gloucester Press,
New York, 1992.
Editors of Time-Life Books. Volcano. Time-Life Books,
Alexandria, VA, 1982.
Erickson, Jon. Rock Formations and Unusual Geologic
Structures. Facts on File, Inc., New York.
Erickson, Jon. Volcanoes and Earthquakes. Tab Books,
Inc., 1988.
Frances, Peter and Jones, Pat. Images of Earth.
Prentice Hall, Inc., New Jersey, 1984.
Harris, Stephen L. Fire and Ice. Pacific Search Press,
1980.
Harris, Stephen L. Agent of Chaos. Mountain Press
Publishing Co., Missoula, Montana, 1990.
Kaye, Glen. Hawaii Volcanoes. KC Publications, 1976.
16
Lutgens, Frederick and Tarbuck, Edward. Essentials of
Geology, 4th ed. Macmillan Co., New York, 1989.
Marvin, Ursula. Continental Drift. Smithsonian Institution
Press, 1973.
Mather, Kirtley F. The Earth Beneath Us. Random
House, New York, 1964.
Miller, Russell. Continents in Collision. Time-Life Books,
Alexandria, VA., 1983.
Redfern, Ron. The Making of a Continent. Times Books,
New York, 1986.
Simpson, Brian. Minerals and Rocks. Galahad Books, New
York, 1974.
Van Cleave, Janice. Earthquakes, Spectacular Science
Projects. John Wiley & Sons, New York, 1993.
Van Cleave, Janice. Volcanoes, Spectacular Science
Projects. John Wiley & Sons, New York, 1994.
Van Rose, Susanna and Marcer, lan F. Volcanoes. British
Museum, 1991.
Van Rose, Susanna. Volcano & Earthquake. Alfred A.
Knopf, 1992.
Walker, Bryce. Earthquake. Time-Life Books,
Alexandria, VA., 1982.
Weiner, Jonathan. Planet Earth. Bantam Books, New York,
1986.
17
Wright, Thomas and Takahashi, Taeko and Griegs, J.D.
Hawaii Volcano Watch. Univ. of Hawaii Press,
1992.
Zike, Dinah. The Earth Science Book. John Wiley &
Sons, Inc. 1993.
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SCRIPT
Mountains are the highest places on earth, towering
thousands of feet above the surrounding land.
Many mountains appear in long belts known as mountain
ranges.
Mountain ranges are like walls that can stretch for hundreds,
even thousands of miles across the land.
Other mountains stand alone, remote from all others.
Some mountains have sharp, jagged peaks... while
others are rounded.
Why are there mountains in some places on earth, but not in
others? How is it that mountains are created? Why are the
mountains so high?
When you look at a globe, you can see the many mountain
ranges on our planet. They're found on every continent.
Globes can be very useful, but...
to understand more about mountains and how they're created,
we have to look deep inside the earth. The earth's interior
consists of several different layers:
the inner core, which is believed to be solid iron and which is
very hot;
the outer core, which is believed to consist of rocky material so
hot and under such great pressure it is in a liquid state;
the mantle, which is not so hot as the outer core and not so
liquid.
19
The mantle's outermost portion is solid. This is the solid outer
portion of the mantle.
Above this is the outermost layer of the earth.. .the crust.
Together, the crust and solid outer portion of the mantle
form the earth's outer shell. They are referred to as the
lithosphere.
It's not always easy to see the earth's crust. It is covered by
vegetation and oceans. But if you could drain the oceans and
strip away our planet's vegetation, the earth might look
something like this.
Now you can see the earth's hard outer shell, and if you look
closely, you can also see the shell is cracked. The red glowing
lines mark the places where the earth's shell is cracked into
small and large pieces called tectonic plates. Each plate carries
a continent, or an ocean basin, or sometimes both. The plates
are moving one to two inches a year, carrying continents and
ocean basins with them.
Millions of years ago, the world looked something like this:
every continent in a different position. They were so close
together, they formed a single supercontinent called Pangaea.
But even then, the plates were moving, a few inches a year,
and kept moving until they reached their present-day
positions. The theory that continents move is called
continental drift.
When you look at a globe today, you are looking at only a
moment in time, because the continents are still moving.
In millions of years, scientists expect the world to look
entirely different.. .every continent in a new position.
Here's why the plates are moving. Scientists believe material
in the mantle is circulating much as it is doing here. The
circulating movement may be caused by heat within the mantle.
20
You can get an idea of how heat can cause a circulating
movement by watching rice as it boils. What you see
happening within this beaker is similar to what's happening ..
.within the earth's mantle. As mantle material moves,
perhaps only inches a year, it causes the plates above it to
move as well.
In some places, plates are moving in opposite directions. They
are moving apart. The area where two plates are moving apart
is called a divergent boundary.
In other places, plates slide past each other. The area where
two plates slide past each other is called a transform boundary.
And in other places, plates are colliding. Most of the
world's great mountain ranges occur where two plates
collide - an area called a convergent boundary.
Here's what happens at some convergent boundaries. In this
example, the plate on the left is carrying a continent and
moving in this direction. The plate on the right is also
carrying a continent but is moving in the opposite direction.
They are colliding. The two plates squeeze up against each
other. Under the incredible pressure, layers of the earth's
surface are compressed and folded, rising high into the air.
These raised layers of earth are called folded mountains...
because of the way they are folded.
You can make your own folded mountains simply by
squeezing the ends of some towels together. The earth's crust
will fold just as these towels will.
The world's highest mountains, the Himalayas, were made in
much the same way.
They were formed when the plate carrying India collided with
the Eurasian plate. Over millions of years, the earth's crust
was squeezed into folds more than five miles high.
21
Today, the Himalayas are growing even higher as the plate
carrying India continues to push against the Eurasian plate. It's
not always easy to see the folds, because the mountains have
been worn into jagged peaks by water, wind and ice.
But if you look closely at mountains like these, in North
America, you can see how rock has been folded under the
great stresses caused by moving plates.
This outline gives you an idea of what these mountains may
have looked like when they were much younger.
When Mt. St. Helens erupted in 1980, it reminded people that
some large mountains are actually volcanoes.
In a matter of seconds, much of Mt. St. Helens was blown
away, the mountain literally losing its top. Dense clouds of
volcanic ash and debris poured out of a newly formed crater
for days on end.
Carried by the wind, the ash was blown hundreds of miles,
burying towns and cities, turning day into night. The pictures
you are now looking at were recorded in mid-afternoon.
The eruption left a ghostly wasteland. Trees toppled like
match sticks. Vehicles tossed about like toys. Crews were
brought in to search for the dead and injured. All told, 62
people were killed. Forests and animal life were wiped out;
and at the mountain's summit - a new crater, nearly 2,000 feet
across and 500 feet deep.
Mt. St. Helens is but one of many volcanic mountains
situated in the Pacific Northwest states of Washington,
Oregon and California.
None of the Pacific Coast volcanoes are currently erupting,
but you can tell they are volcanoes. Unlike most other
mountains, they stand alone, great distances between them.
22
And unlike the jagged peaks of other mountains, the shapes of
most volcanoes are symmetrical, one side matches the other.
As with folded mountains, the Pacific Coast volcanoes occur
near a convergent boundary. The plate carrying the ocean basin
is moving in this direction. And the plate carrying the
continent is moving in this direction. Here's what happens.
Because the plate carrying the ocean basin is heavier, it will
dive beneath the plate carrying the continent. As it does so,
tremendous heat and pressure are created, causing solid rock to
liquefy into a material called magma. Magma is similar to lava
that erupts from volcanoes. The magma rises in large globs
into the plate carrying the continent. Eventually, the magma
stops rising. Some of the globs may form a magma chamber.
As more and more magma adds to the chamber, pressures
build. Some of the magma finds its way to the surface, where
it can erupt.
Mt. St. Helens erupted in much this same way.
Some volcanoes occur far from plate boundaries. The
Hawaiian Islands are thousands of miles from the nearest plate
boundary, yet this area is among the most volcanically active
areas in the world.
Scientists believe a hot spot exists in the earth's mantle
below Hawaii.
Hot spots are areas where magma has found its way through
the earth's crust.. .emerging on the ocean floor, where it
becomes hardened by cold ocean water.
More magma follows, adding to the formation of an
underwater volcanic dome.
The dome becomes larger and larger, and may, after
thousands of years, rise above sea level.
23
Every island in the Hawaiian chain, as well as many others
around the world, were formed in just this way.
Seldom do hot spot volcanoes erupt with the explosive force of
volcanoes like Mt. St. Helens, but what they lack in explosive
impact, they make up for in showy displays.
Lava fountains are typical of these kinds of volcanoes. The
lava can shoot hundreds of feet into the sky, and an eruption
like this can last for days.
Lava can also erupt through cracks in the ground, creating
walls of fire, or lava curtains.
A lava curtain can sometimes be more than a mile long and
reach a height of over 150 feet.
When lava travels downhill, it can create rivers of fire. In
some places, the lava slows to a stop, hardening into black
rock as it cools.
But in other places, the lava doesn't stop, reaching the ocean.
Steam explosions are common as the lava explodes as it
hardens.
New shorelines form under clouds of hissing steam.
When watching scenes like this, it's easy to forget that the
Hawaiian Islands are actually mountains, volcanic mountains.
These mountains in Wyoming are examples of a third type of
mountain. They are called.. .fault-block mountains. Here's
how fault-block mountains are created.
The earth's crust is filled with cracks, the way this rock is
filled with cracks.
24
Some cracks in the earth's crust are called faults, and faults are
places that are important to scientists.
One side of a fault tries to move in one direction, the other side
may try to move in the opposite direction. But the two sides
are locked in place. They can't move until enough stress builds
up to move them.
If you bend a stick slowly, you will find it won't break until
sufficient stress builds up.
That's what happens deep underground. The fault will remain
locked until enough stress builds up, and then it will suddenly
release, as one side of the fault slides past the other with a
tremendous burst of energy. The energy that is released is in
the form of seismic waves which radiate, or move outward.
If you've ever thrown a stone into a pond, you've seen
waves move outward in all directions.
The waves in this pond are similar to the waves caused by
movement along a fault.
If the disturbance is big enough, the waves will eventually
reach the surface, where they can cause considerable surface
movement which is referred to as an earthquake.
Each year there are thousands of earthquakes throughout the
world. While most are small, some are large, like this one
which struck California. Sixty-seven people were killed and
damage was widespread. So what does all this have to do with
fault-block mountains?
Well, some faults reach all the way to the earth's surface, and
over millions of years, and countless earthquakes, one side of
the fault may rise above the other side.
25
The uplifted section may rise miles into the sky. Mountains
made this way often have one side that is very steep.
These fault-block mountains rise nearly two miles over the
valley beneath them. This line shows how one section of the
earth's crust has risen above another section.
Mountains are so high, they are often covered by clouds...
and fog that creeps through forests and up ridge lines.
As you travel up a mountain, it becomes colder and snow
comes often. In some mountains, because they are so high,
the snow falls throughout the year.
Each spring, much of the snow melts, and the mountains are
alive with the sound of rushing water.
Spring is the time of renewed life in the mountains.
Some of the world's biggest trees are found in mountains.
This giant redwood has a diameter of over 30 feet and it is
more than 200 feet high.
As you go up a mountain, the trees get fewer and smaller.
The few trees you do find are bent from the strong winds,
and twisted by the freezing cold.
This is the bristlecone pine tree, the oldest living thing. Some
trees are over 2,000 years old. Many look dead, but they're
not.
Mountains are important in many ways. From mountain rock,
people mine valuable minerals and ores.
Mountains provide water for our farms and cities. Aqueducts
like this cany mountain snow-melt hundreds of miles, to
places where there is little water.
26
And from mountain slopes, we log trees with which we
build our homes and many products.
Mountain ranges may stretch for hundreds of miles, creating a
wall of mountains that serve as barriers to travel, and altering
weather patterns.
Mountains block clouds, and in some places, create dense
forests on one side of the range.. .while the other side may be
a desert.
Mountains teach us about the past. In many mountains, you
can find fossils of sea life. The fossils got there when layers of
the earth's crust, which were once underwater, were thrust into
the air.
Mountains teach us about the present. Near the tops of some
mountains, scientists have placed equipment that tell us about
the effects of air pollution.
Mountains provide recreational activities for fishing, boating,
skiing, hiking and much more.
Finally, mountains add beauty and grandeur to our world.
In this program, we've seen how the earth's shell is composed
of more than a dozen plates which move in different directions,
carrying continents and ocean basins with them.
We've seen that folded mountains are formed when two
plates carrying continents, squeeze against each other,
causing the earth's crust to fold.
The world's highest mountains, the Himalayas, are
examples of folded mountains.
Some volcanoes are formed when a plate carrying an ocean
basin dives beneath a plate carrying a continent, causing
magma to rise to the surface.
27
Many volcanoes have symmetrical sides.
Hot spot volcanoes occur far from plate boundaries, where
magma has found its way up through the earth's crust.
Hot spot volcanoes seldom explode, but they do put on
showy displays.
Fault-block mountains are formed when sections of the
earth's crust rise above other sections.
Fault-block mountains have one side that rises abruptly from a
flat plain.
We've seen how mountains are important to wildlife and
people.. .and how mountain ranges alter the weather and even
the way we live.
Mountains are the highest places on earth. Their very height
should remind us of the great forces at work in our planet.
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CLOZE EVALUATION QUESTIONS
WHY ARE THE MOUNTAINS SO HIGH?
NAME_______
DIRECTIONS: Select the answer, from the four choices given, by circling the correct letter.
1. Millions of years ago the earth was quite different than it is today. The continents
were all together and formed one large continent, called _____. The continents
and the plates that they rested upon have moved to their present position after
millions of years.
1.
A.
B.
C.
D.
Eurasian
Sub-Arctic
Pangea
Afro-Asia
2. After many more millions of years the earth will look entirely different than it
does today. One reason is because material in the _____ is circulating, or
moving. This movement is caused by great heat and the continents resting on this
material will continue to move ever so slightly.
2.
A.
B.
C.
D.
core
crust
oceans
mantle
3. Some mountains are formed when the plates carrying continents on them
collide with each other. Due to great pressure the layers are compressed and
folded. When the plate carrying India collided with the Eurasian, the _____
Mountains were formed. This type of folded mountain can also be found in other
parts of the world.
3.
A.
B.
C.
D.
Himalaya
Rocky
Appalachian
Alps
4. Another type of mountain building process is the formation of volcanoes.
Magma below the earth works itself up to the surface and with enough pressure
volcanoes will form. The Pacific Northwest states of California, Oregon and _____
have volcanic formations.
4.
A.
B.
C.
D.
Nevada
Washington
Utah
Montana
5. Mountains are important to us in many ways. They provide water for our farms
and cities. Some mountains have valuable _____ like gold and silver. Mountain
ranges also affect the weather in the areas in which they are found.
5.
A.
B.
C.
D.
substances
materials
objects
minerals
6. Scientists look below the surface of the earth to understand the process of
mountain-building. They believe that liquid matter in the mantle is moving or circulating. This causes the earth's plates to move. When two plates move in
opposite directions, the space between them is called a _____. Most are located
beneath the oceans.
6.
A.
B.
C.
D.
convergent boundary
divergent boundary
transform boundary
separation
7. There are different types of mountain-building processes. One type occurs
when two plates squeeze against each other. Under the incredible pressure,
layers of the earth's surface rise high into the air. The types of mountains formed
are known as _____ mountains. A good example is the Himalayas.
7.
A. volcanic B.
folded C.
fault-block D.
extended
8. The grinding of the earth's plates has been going on for millions of years.
One result of this process is a crack in the earth's surface, called a ________.
One side of this crack tries to move in one direction while the other side moves in
the opposite direction. The earth's plates remain locked in position until stress
from below forces them to move.
8.
A. break B.
space C. fault
D. separation
9. Some of the earth's cracks or faults reach all the way up to the earth's surface. If
one side of the fault is large enough it may rise above the other side of the fault,
forming _____ mountains. This type of mountain usually has one side that is
steeper than the other.
9.
A. fault-block
B. folded C.
volcanic D.
extended
10. There are places around the earth where magma is able to rise to the earth's
surface. As more and more magma builds up, pressure is increased and magma
erupts, forming another type of mountain, called _____. Typical examples are the
Hawaiian Islands and Mt. St. Helens.
10. A. extended B.
folded C.
fault-block D.
volcanic
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