3 8 changes on earth (earth science)

Earth Science

by Cassandra Jenkins

Genre

Nonfiction

Comprehension Skill

Sequence

Text Features

• Captions
• Call Outs
• Glossary

Science Content

Changes on
Earth

Scott Foresman Science 3.8

ISBN 0-328-13829-0

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Vocabulary

What did you learn?

core

1. What forces can cause erosion?

crust

2. Name the different layers of Earth.

erosion

3. How do volcanoes erupt?

landform

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?

Changes on Earth
by Cassandra Jenkins

lava
magma
mantle
weathering

Illustrations: 3, 4, 7 Big Sesh Studios
Photographs: 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
O’Hara/Corbis, (CR) ©Royalty-Free/Corbis; 6 ©Photographer’s 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

What are Earth’s layers?
Earth’s 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

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.

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.

Crust
Mantle

Core

2

3


Shapes on Earth’s Surface

A glacier is a moving body of ice. It slowly moves

A landform is a solid feature on Earth’s crust.
Mountains, hills, and valleys, are landforms. Other
features include bodies of water. There are many

downhill. A volcano is an opening in Earth’s crust.
Hot, melted rock is forced through it. Some mountains
form when pieces of rock are pushed along cracks in
Earth’s crust. A lake forms when water flows slowly

different types of landforms on Earth.
Forces shape these landforms. Moving water is a

enough to fill up an area.

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.

Volcano

Mountain
Lake

River
Hill

Valley

Plateau

Glacier

Plain
Do you recognize
these landforms?

Ocean
Coast

4

This picture shows a
mountain, a kind of
landform, and a lake.

5


What are volcanoes and
earthquakes?
How Do Volcanoes Form?
Volcanoes start in the mantle. This is where

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

magma forms. Magma is hot, partly melted rock that

through a bowl-shaped

is under pressure from gases it contains. This pressure

crater at the top of

forces it up through Earth’s crust. The hot material

the volcano.

erupts through an opening in a volcano.
Crater

Lava is the material that erupts from a volcano.

Central vent

Lava has ash, cinders, and hot rock in it. As lava
cools, it becomes new crust.
Side vent

Side vent

Magma

chamber

This lava was
once magma
inside Earth.

6

7


Earthquakes
Parts of Earth’s crust can shift suddenly. This causes

Earthquake Damage
How much earthquake damage occurs depends on

the ground to vibrate. This shaking is called an

how long the crust shakes. It also depends on how

earthquake. Most earthquakes begin along a fault.

close the earthquake is to the surface. Earthquakes

A fault is a large crack in Earth’s crust.

can happen very close to a city. This causes a lot of

Earthquake vibrations move as waves through

Earth. They also move up and down. The waves can

damage to buildings, bridges, pipes, and roads.
An earthquake can cause landslides. Landslides are

cause cracks. They can pile up rubble in areas around

downhill movements of rocks and earth. Landslides

the parts of the crust that moved.

can happen on the land or the ocean floor. Landslides
underwater can cause huge waves. Landslides on the
land can bury large areas.

Earthquakes can cause
damage in cities and in
nature.

8

9


What are weathering
and erosion?

Water mixed with decayed
material in soil can also cause

Boulder

weathering. This water changes
the minerals in the rock. The

Weathering
Landforms are always changing. This happens

rock grows weak and starts to
break apart. Water can also seep

when rocks in landforms break apart. Weathering is

in and freeze in the cracks of a

any action that breaks rocks into smaller pieces.

rock. Then the water expands.

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.

Cobble

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

Pebble

the ground as a glacier moves.
This makes valleys wide and
smooth. Rocks of all sizes drop

Sand

to the ground when the glacier
melts. These rocks and soil line

Silt

the edges where the glacier used
to be.

Clay
Look at how weathering
has broken down this
boulder into smaller and
smaller pieces.

10

11

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

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 aren’t many plants
to hold them down. The particles bump into rocks
and cause small grains to break
off. Slowly the rocks change.

bits of rock. During floods, mud and sand flow over a
river’s 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.

12

13


Living things can cause erosion. Some squirrels

Gravity causes erosion by pulling rocks downhill.

tunnel through soil. Worms can mix and carry soil to

This material moves slowly unless the slope is steep.

new places. Groups of ants move soil to make nests.

Weathered material moves very quickly on steep

When an animal tunnels, it allows water and air

slopes! The movement of wet soil is called a mudflow.

into the ground. Then the air and water continue

When rocks slide quickly down a hill, it is called

the erosion.

a rockslide.

This hillside eroded. The side
of the hill slumped down.

Erosion caused the
hole in this cliff.

14

15

Glossary
Vocabulary

What did you learn?

core
core

the innermost layer of Earth

1. What forces can cause erosion?

crust
crust

the outer layer of Earth

2. Name the different layers of Earth.

erosion
erosion

the movement of weathered material

3. How do volcanoes erupt?

landform
landform

a solid feature formed on Earth’s crust

4.

lava
lava

molten rock that erupts from a

magma

volcano

magma

hot, partly melted rock that is under

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?

mantle

weathering

pressure

mantle

the part of Earth just beneath the crust

weathering

any action that breaks rocks into
smaller pieces

Illustrations: 3, 4, 7 Big Sesh Studios
Photographs: 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
O’Hara/Corbis, (CR) ©Royalty-Free/Corbis; 6 ©Photographer’s 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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