Earth to change.pdf
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Transcript of Earth to change.pdf
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by Cassandra Jenkins
Scott Foresman Science 3.8
Genre Comprehension Skill Text Features Science Content
Nonfi ction Sequence Captions
Call Outs
Glossary
Changes on Earth
ISBN 0-328-13829-0
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Vocabularycore
crust
erosion
landform
lava
magma
mantle
weathering
What did you learn?1. What forces can cause erosion?
2. Name the different layers of Earth.
3. How do volcanoes erupt?
4. In this book you have read about how weathering affects landforms. Write to explain how weathering can change landforms. Use examples from the book to support your answer.
5. Sequence What happens during an earthquake?
Illustrations: 3, 4, 7 Big Sesh StudiosPhotographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd)Opener: David Muench/Corbis; Title Page: Big Sesh Studios; 2 David Muench/Corbis; 5 (BC) Pat OHara/Corbis, (CR) Royalty-Free/Corbis; 6 Photographers Choice/Getty Images; 8 (CR) Spencer Grant/Photo Researchers, Inc., (B) Lloyd Cluff/Corbis; 9 (BL) Ken M. John/Photo Researchers, Inc., (BR) La Prensa Grafica/AP/Wide World Photos; 10 (R) Fred Whitehead/Animals Animals/Earth Scenes, (BR) Jeremy Horner/Corbis; 11 Natural History Museum/DK Images; 12 DK Images; 13 La Prensa Grafica/AP/Wide World Photos; 14 William Manning/Corbis; 15 David Muench/Corbis
ISBN: 0-328-13829-0
Copyright Pearson Education, Inc.
All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.
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Changes on Earthby Cassandra Jenkins
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2What are Earths layers?Earths Layers
Earth is divided into three layers. The crust is the
outer layer of Earth. It is made up of different kinds of
rock. The thickness of the crust is different in different
places. The crust is about 37 kilometers (23 miles)
thick under the continents. Compare Earth to a peach.
The crust would be the skin of the peach.
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3
The mantle is below the crust. It is made up of
very hot rocks. It can flow like thick toothpaste.
The core is the innermost layer of Earth. It is made
up of metal. The core is so hot that it could melt. But
it is packed tightly together and stays mostly solid. Its
outer part is a very hot liquid.
Crust
Core
Mantle
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4Shapes on Earths Surface
A landform is a solid feature on Earths crust.
Mountains, hills, and valleys, are landforms. Other
features include bodies of water. There are many
different types of landforms on Earth.
Forces shape these landforms. Moving water is a
strong force. Rivers can act as saws. Sand and pebbles
in the water slowly cut through rock. Flooding rivers
leave silt, sand, and pebbles on their banks. These
things help form valleys.
GlacierValley Plateau
Ocean
Coast
Do you recognize these landforms?
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5
A glacier is a moving body of ice. It slowly moves
downhill. A volcano is an opening in Earths crust.
Hot, melted rock is forced through it. Some mountains
form when pieces of rock are pushed along cracks in
Earths crust. A lake forms when water flows slowly
enough to fill up an area.
Volcano Mountain
LakeRiver
This picture shows a mountain, a kind of landform, and a lake.
Plain
Hill
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6What are volcanoes and earthquakes?How Do Volcanoes Form?
Volcanoes start in the mantle. This is where
magma forms. Magma is hot, partly melted rock that
is under pressure from gases it contains. This pressure
forces it up through Earths crust. The hot material
erupts through an opening in a volcano.
Lava is the material that erupts from a volcano.
Lava has ash, cinders, and hot rock in it. As lava
cools, it becomes new crust.
This lava was once magma inside Earth.
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7
Volcanoes
Magma collects in large pockets. These pockets
are called magma chambers. As magma leaves a
chamber, it moves up a tunnel or vent. Sometimes
magma escapes and erupts from a side vent. But
most magma erupts through a central vent. It erupts
through a bowl-shaped
crater at the top of
the volcano.
Crater Central vent
Side vent
Magma chamber
Side vent
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Earthquakes
Parts of Earths crust can shift suddenly. This causes
the ground to vibrate. This shaking is called an
earthquake. Most earthquakes begin along a fault.
A fault is a large crack in Earths crust.
Earthquake vibrations move as waves through
Earth. They also move up and down. The waves can
cause cracks. They can pile up rubble in areas around
the parts of the crust that moved.
8
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Earthquake Damage
How much earthquake damage occurs depends on
how long the crust shakes. It also depends on how
close the earthquake is to the surface. Earthquakes
can happen very close to a city. This causes a lot of
damage to buildings, bridges, pipes, and roads.
An earthquake can cause landslides. Landslides are
downhill movements of rocks and earth. Landslides
can happen on the land or the ocean floor. Landslides
underwater can cause huge waves. Landslides on the
land can bury large areas.
9
Earthquakes can cause damage in cities and in nature.
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What are weathering and erosion?Weathering
Landforms are always changing. This happens
when rocks in landforms break apart. Weathering is
any action that breaks rocks into smaller pieces.
Weathering goes on all the time. It causes changes
over time. Some changes might take a year. Others
could take hundreds of years.
Plants can cause weathering. Their roots grow into
rocks. As the roots grow, they break apart rocks.
10
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11
Water mixed with decayed
material in soil can also cause
weathering. This water changes
the minerals in the rock. The
rock grows weak and starts to
break apart. Water can also seep
in and freeze in the cracks of a
rock. Then the water expands.
Ice pushes against the rock and
breaks it apart over time.
Ice changes rocks in a different
way. Glaciers are huge bodies of
ice. Rocks and ice scrape against
the ground as a glacier moves.
This makes valleys wide and
smooth. Rocks of all sizes drop
to the ground when the glacier
melts. These rocks and soil line
the edges where the glacier used
to be.
Look at how weathering has broken down this boulder into smaller and smaller pieces.
Boulder
Cobble
Pebble
Sand
Silt
Clay
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12
Erosion
Sometimes weathered materials are picked up and
carried away. The movement of weathered materials is
called erosion. Glaciers, gravity, wind, and water can
cause erosion.
Water erosion is the most common form. Rivers move
bits of rock. During floods, mud and sand flow over a
rivers banks. Rainwater washes soil away from hills.
Erosion can make new islands. Rivers carry rocks
and soil to the ocean. They build up over time into
islands. Then wind and waves
change their shape.
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13
In dry places such as deserts, wind often causes
erosion. Wind can pick up dry sand and soil. It blows
them to other places since there arent many plants
to hold them down. The particles bump into rocks
and cause small grains to break
off. Slowly the rocks change.
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Living things can cause erosion. Some squirrels
tunnel through soil. Worms can mix and carry soil to
new places. Groups of ants move soil to make nests.
When an animal tunnels, it allows water and air
into the ground. Then the air and water continue
the erosion.
14
Erosion caused the hole in this cliff.
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Gravity causes erosion by pulling rocks downhill.
This material moves slowly unless the slope is steep.
Weathered material moves very quickly on steep
slopes! The movement of wet soil is called a mudflow.
When rocks slide quickly down a hill, it is called
a rockslide.
15
This hillside eroded. The side of the hill slumped down.
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16
Glossary
core the innermost layer of Earth
crust the outer layer of Earth
erosion the movement of weathered material
landform a solid feature formed on Earths crust
lava molten rock that erupts from a
volcano
magma hot, partly melted rock that is under
pressure
mantle the part of Earth just beneath the crust
weathering any action that breaks rocks into
smaller pieces
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Vocabularycore
crust
erosion
landform
lava
magma
mantle
weathering
What did you learn?1. What forces can cause erosion?
2. Name the different layers of Earth.
3. How do volcanoes erupt?
4. In this book you have read about how weathering affects landforms. Write to explain how weathering can change landforms. Use examples from the book to support your answer.
5. Sequence What happens during an earthquake?
Illustrations: 3, 4, 7 Big Sesh StudiosPhotographs: Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the property of Scott Foresman, a division of Pearson Education. Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R) Background (Bkgd)Opener: David Muench/Corbis; Title Page: Big Sesh Studios; 2 David Muench/Corbis; 5 (BC) Pat OHara/Corbis, (CR) Royalty-Free/Corbis; 6 Photographers Choice/Getty Images; 8 (CR) Spencer Grant/Photo Researchers, Inc., (B) Lloyd Cluff/Corbis; 9 (BL) Ken M. John/Photo Researchers, Inc., (BR) La Prensa Grafica/AP/Wide World Photos; 10 (R) Fred Whitehead/Animals Animals/Earth Scenes, (BR) Jeremy Horner/Corbis; 11 Natural History Museum/DK Images; 12 DK Images; 13 La Prensa Grafica/AP/Wide World Photos; 14 William Manning/Corbis; 15 David Muench/Corbis
ISBN: 0-328-13829-0
Copyright Pearson Education, Inc.
All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to: Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.
3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 05
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