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Reading Essentials and Study Guide 1Thinking Like a Geographer

Drawing From ExperienceHave you ever used a road map on a long car trip? Have you

glanced at a subway map while riding a subway? If so, you have used geography!

In this section, you will learn what geography is. You will also learn how geographers study places and people.

LOOKING AT THE EARTH

remains of a living thing, such as a humanfossilitem such as a tool, pottery, painting, or weapon from a past societyartifact

phers gather many kinds of information about a placecomputer software that helps geogra-geographic information systems (GIS)

earth that tells the exact locations of placesgroup of satellites traveling around theGlobal Positioning System (GPS)

natural surroundingsenvironmentindividual features of the land, like mountains and valleyslandform

the study of the earth and its land, water, plants, animals, and peoplegeography

Key Terms

Reading Essentials and Study Guide 1

Read to LearnIntroduction

Mount Etna in Italy is one of the world’s most active volcanoes. It has erupted twice between 2001 and 2003. Scientists who study volcanoes constantly watch Mount Etna. They hope to learn about the volcano. They want to be able to warn people when the volcano will erupt again. This warning could save many lives. Studying volcanoes is one example of how geography can help the world.

Geography is the study of the earth. Physical geography is the study of the earth’s land, water, plants, and animals. Human geography is the study of people and where and how they live in their environment. It also compares different groups to one another. 9. Why do scientists study Mount Etna?

8.6.4.2.

Example

7.5.3.1.

Example

RegionsEnvironmentPeopleA place

Geographers study:

Copyright © by The McGraw-Hill Companies, Inc.

geographers raphers study. For each item listed below, give two examples of details

Use the chart below to help you take notes. Think about what geog-Organizing Your Thoughts

A Geographer’s View of PlaceGeographers study places. They want to know where something is

on the earth. They also want to know what the place is like. To learn about a place, they study its landforms. These are features of the land. Mountains, valleys, and bodies of water are landforms. Does the place have freshwater? Is it near the ocean? How hot or cold is the place? How much does it rain there? Does the place have resources like minerals, metals, and trees? Geographers study the people in a place. Do many people live there? Do they live far apart? What religions do they follow? What work do they do? What languages do they speak?

Environment is the natural surroundings of a place. Geographers want to know how people use their environment. People near the sea might catch fish for a living. People on rich soil might farm for a living.

Geographers also study how people change their environment. When people build dams, they change their environment. They change the way rivers flow.

Geographers also look at the big picture. They study how places relate to one another. Areas that are alike in many ways are regions. Regions can be small. Your town can be a region. Regions can be large. The western United States is a region. Even several countries can be a region. The people may speak the same language. Their ways of life may be alike.10. Give an example of a landform near your town.


Reading Essentials and Study Guide 1 (continued)Copyright © by The McGraw-Hill

The Tools of GeographyGeographers use maps and globes to study the earth. Different

types of maps show certain features of a place. Geographers gather information to make good maps. One way to gather information is to take photographs from high above the earth. These photos are called Landsat images. They show the shape of the land. They also show what plants cover an area.

The Global Positioning System (GPS) is a group of satellites circling the earth. The satellites send signals back to special devices called receivers on the earth. The signals tell exactly where places are located. People can then make good maps.

Computers also help geographers do their work. Geographic information systems (GIS) is special computer software. Geographers gather different kinds of information about a place. They put this information in the GIS. The GIS combines the information, and then places the information on special maps. Geographers can then look at different kinds of information about the same place. For example, they can see where different animals live in the Amazon rain forest. This information helps people make good decisions about how to use the land.11. Why do geographers need to know exactly where places are

located on the earth?

Uses of GeographyPeople use geography to plan. Government leaders use it to plan

new community services. Companies use it to see where people are moving. They can then plan to open a new store there.

People use geography to make good decisions. City leaders might use it to decide where to put a new building or sewer.

People use geography to manage resources. Oil and coal are kinds of natural resources. These resources are in limited supply. Geography can help find more of these. Trees are also resources. People can plant more to replace what they use. Geography can help manage resources so people will not use them all up.

12. Name three natural resources.

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Reading Essentials and Study Guide 1

Clues to Our PastHistorians, archaeologists, and anthropologists are scientists who

study early times. They use tools to help them.Historians learn about the past by looking at written records. They

study diaries and newspapers. However, some scientists study prehistory. Prehistory is the time before writing was invented.

Archaeologists and anthropologists learn about prehistory by studying artifacts. Artifacts are items such as tools, pottery, and weapons from ancient times. Scientists also study the remains of humans, or human fossils. Artifacts such as tools and weapons help scientists learn how early humans lived. Bones, animal skins, and plant seeds tell scientists what early people ate.13. How might a scientist determine what kinds of animals early

people ate?


Reading Essentials and Study Guide 2The Earth in Space

Drawing From ExperienceOn what day is your birthday? Are the temperatures about the

same on your birthday from year to year? Have you ever wondered why?

The last section described how geographers study people and places. This section discusses how the sun makes life possible. You will also learn about seasons.



Equator; when day and night are of equal length in both hemispheresthe day in March and September when the sun appears directly over theequinox

hours of sunlightTropic of Capricorn; the day in the Northern Hemisphere with the fewest

the day in December when the sun appears directly over thewinter solsticeof sunlightTropic of Cancer; the day in the Northern Hemisphere with the most hours

the day in June when the sun appears directly over the summer solsticea year that has an extra day; occurs every fourth yearleap year

one complete orbit of a planet around the sunrevolutionPolesimaginary line that runs through Earth’s center between the North and Southaxis

layer of air surrounding Earthatmospherepath a planet follows in revolving around the sunorbit

group of planets and other bodies that revolve around the sunsolar system

Key Terms

Organizing Your ThoughtsUse the diagram on the next page to help you take notes. Assume

that you live in the northern half of the world (the Northern Hemisphere). In the first boxes, name the days that begin each season. In the second column, note where the sun is located above the earth on those days. Then, in the third set of boxes, describe the amount of sunlight on those four days.Reading Essentials and Study Guide 2


Imagine you are flying through space. You look down. There is a blue and white ball. It looks like a marble floating in the dark. This marble is Earth! The sun provides heat and life for our planet. Earth and eight other planets travel around the sun. Thousands of smaller bodies do as well. All of these bodies plus the sun form the solar system. Earth is the third planet from the sun. 13. Why do you think Earth looks like a blue and white marble from

space?

Amount of SunlightLocation of SunDay

12.11.10.

9.8.7.

6.5.4.

3.2.1.


Reading Essentials and Study Guide 2 (continued)

The sun is made of very hot gases. It gives off light and heat. Without this light and heat, nothing could live on Earth.

The atmosphere is the layer of air surrounding Earth. This air makes life on Earth possible. Most of the atmosphere is nitrogen and oxygen. Humans and animals need oxygen to breathe. The atmosphere protects life in other ways, too. It holds in the sun’s heat. This keeps Earth from being too cold. The atmosphere also keeps some heat out. This keeps Earth from being too hot. The atmosphere also blocks some of the sun’s dangerous rays from reaching Earth.

The moon travels around Earth in about 30 days. The moon is cold and rocky. It has no water. It has no atmosphere. It has no light. Light from the sun bounces off the moon. This makes it look like the moon is shining.

Earth rotates, or spins, on its axis. The axis is an imaginary line that runs through Earth’s center. It goes between the North and South Poles. Earth finishes one complete spin on its axis in 24 hours. For this reason, a day is 24 hours long. As Earth turns, parts of it go in and out of sunlight. When a part faces the sun, it has day. When it faces away from the sun, it has night.

Earth moves in another way, too. It makes one revolution, or complete trip around the sun, in 365 1/4 days. This is one year. Every four years, the extra 1/4 days add up to a full day. In that year, our

of rocks and dust go around each one.

of gas, not solid like rocks. They have many moons. They spin fast. Rings

Jupiter, Saturn, Neptune, and Uranus. They are huge. They are like balls

The other type is like Jupiter. The planets in the second type areThey have few or no moons. They spin slowly.like Earth are Mercury, Venus, Mars, and Pluto. They are solid and small.

Planets can be divided into two types. One type is like Earth. Planets

paths are ovals, like stretched-out circles.

Theorbit.

Each planet travels around the sun along its own path, or The Solar System



calendar has an extra day: February 29. A year that has this extra day is called a leap year.14. How many full days are in a leap year?

The Sun and the SeasonsEarth is tilted on its axis. It takes one year for Earth to travel

around the sun. As it does, its tilt makes the seasons change. The sun’s rays fall directly on the northern and southern halves of Earth at different times. Direct rays bring more warmth than slanted rays. When the northern half of Earth receives the direct rays, the people there feel the warmth of summer. When that half receives slanted rays, the people are having winter.

Four days mark the start of the four seasons. The summer solstice is on or about June 21. During this time, the North Pole is tilted toward the sun. The sun appears directly over the Tropic of Cancer. This day in the northern half of Earth has more hours of sunlight than any other dayReading Essentials and Study Guide 2

and is the first day of summer. In the southern half, it is the first day of winter. The day has the fewest hours of sunlight there.

About December 22, the North Pole is tilted away from the sun.

The sun appears directly over the Tropic of Capricorn. In the northern half of the world, this day is the winter solstice. It has the fewest


hours of sunlight. It is the first day of winter. In the southern half, this day is the start of summer.

The equinoxes mark the starts of spring and fall. On these two days, day and night are of equal length in both halves of the world. The sun shines directly over the Equator. About March 21 is the vernal equinox. It is the start of spring in the north. About September 23 is the autumnal equinox. It is the start of fall in the north.15. What makes the seasons change?

Reading Essentials and Study Guide 3Forces Shaping the Earth

Have you ever picked up rocks along a stream? Were many of them smooth? Did you wonder how they got that way?

In the last section, you learned about the sun, planets, and seasons. This section describes forces inside and on top of the earth. These forces shape the land.


Copyright © by The McGraw-Hill giant sheet of iceglacier

icethe moving or wearing away of weathered material by water, wind, anderosion

frost, chemicals, and plantsthe breaking down of surface rocks into smaller pieces by water,weathering

s crust’crack in the earthfault huge wave caused by undersea earthquakestsunami

s crust’violent and sudden movement of the earthearthquake of rock

s crust is made up of huge, moving plates’theory that the earthplate tectonics one of the seven major land areas of the earthcontinent

outer layer of the earthcrust ing volcanic eruptions

s surface dur-’s mantle that flows to the earth’melted rock from the earthmagma s core’layer of solid and melted rock surrounding the earthmantle

center of the earth that is solid metal and rock surrounded by hot liquid metalcore

Key Terms

Drawing From Experience

Organizing Your ThoughtsUse the diagram on the next page to help you take notes. Name

the layers of the earth. Some layers have two parts. Write what each layer is made of.Reading Essentials and Study Guide 3

Earth Name Made of


Just think. Thousands of miles inside, the earth is so hot that metal is melted. Forces inside the earth formed features on top. They created landforms like mountains and deserts. These features are still changing today. Some forces work slowly. They may take thousands of years to make changes. Others make sudden changes. Some forces destroy things on the surface. 9.Give an example of one of the earth’s forces that can destroy things.

Inside the EarthThe earth has three layers. They are the core, mantle, and

crust. Think about a melon cut in half. The earth’s core is like the center of the melon. The mantle is like the part of the melon that

8.7.

6.

5.4.

3.

2.1.


you eat. The earth’s crust is the top layer. It is like the melon’s skin. Let’s take a closer look.

The earth’s core is its center. It is made of hot iron mixed with other metals and rock. The core has two parts. The very center is solid. The outer layer is hot liquid metal. Around the core is the mantle. This is a layer of rock. It is 1,800 miles thick. The mantle has two parts. The inside part is solid rock. The outside part sometimes melts. This melted rock is called magma. When a volcano explodes, magma flows to the earth’s surface.LOOKING AT THE EARTH


The top layer of the earth is the crust. It is thinner than the other layers. It is about 31 to 62 miles deep. The ocean floors are part of the crust. The crust is thinnest there. The crust also includes the continents.These are seven huge land areas. The crust is thicker below these land areas.10. Magma is part of which layer of the earth?

Forces Beneath the Earth’s CrustPlate tectonics is a theory about the earth. It states that the

crust is not a solid shell. Instead, it is made up of plates. These plates are huge slabs of rock that move. The plates float on the mantle’s liquid rock. They often move in different directions. Oceans and continents sit on these giant plates.

Study a map of the world. Look at the eastern side of South America. Now look at the western side of Africa. They look like they could fit together, like puzzle pieces. Actually, they once were fit together. Millions of years ago, the continents moved apart. The plates are still moving. They move too slowly to feel. They move a few inches a year.

Sometimes plates pull apart. Sometimes they push together. Two continental plates smashing together makes mountains.

A continental plate is thicker than an ocean plate. When these two kinds of plates hit, the continental plate will slide over the ocean

plate. The edge of the lower plate melts. The liquid rock may erupt in a volcano. The two sliding plates may also cause the earth’s crust to


move suddenly. This is an earthquake. Earthquakes can destroy buildings. Earthquakes under the ocean can cause huge waves called tsunamis. These waves can flood towns next to the ocean.

Sometimes two plates do not hit head-on. They rub their sides together as they move different ways. This causes faults.These are cracks in the earth’s crust. Earthquakes can happen near faults. 11. What are plates?

Forces Shaping LandformsForces inside the earth cause volcanoes and earthquakes. These

change the earth’s landforms. Forces on the earth’s surface keep changing these landforms.Reading Essentials and Study Guide 3

Weathering is the process of breaking rocks into smaller and smaller pieces. Huge rocks become gravel. Gravel becomes sand. Sand becomes soil. Water and frost cause this to happen. Water drips into cracks in rocks and freezes. Ice gets bigger as it freezes. As the ice gets bigger in the crack, it splits the rock.

Chemicals and plants also cause weathering. Chemicals in dirty air mix with rain. The rain falls to the earth. The chemicals eat away the rocks. Plant seeds fall into the cracks. The plants spread their roots. In time, the roots cause huge rocks to break apart.

Erosion is the process of wearing away or moving weathered material. Water, wind, and ice cause erosion. They carry away rocks and soil. Rain picks up sand and dirt as it runs downhill. Rivers pick up sand and soil along their banks.

Wind also blows soil and sand to other places. Sand in the wind works like sandpaper. It hits rocks and rubs them smooth.

Ice is the third cause of erosion. Glaciers are giant sheets of ice. They form high in mountains. As they move, they change the land. They carry rocks down the mountains. The rocks act like sandpaper, too. They grind everything below them as they move. In time, the weight of the ice cuts valleys at the mountains’ base.

12. What are the three causes of erosion?

Reading Essentials and Study Guide 4Landforms and Waterways




s mouth and built up over time’soil and sand deposited at a riverdelta body of water, wider than a strait, between two pieces of landchannel

narrow body of water between two pieces of landstrait deep valley on the ocean floortrench

underwater plateau that lies off each coast of a continentcontinental shelf piece of land smaller than a continent and completely surrounded by waterisland

piece of land with water on three sidespeninsula narrow piece of land that connects two larger pieces of landisthmus flat land at higher elevations than plainsplateau

low-lying stretch of flat or gently rolling landplain height above sea levelelevation

Key Terms

Drawing From ExperienceWhat is the land around you like? Is it mountainous or hilly? Is it

fairly flat? Are there rivers or an ocean nearby? Think about a place very different from yours. How would your life change if you moved there?

The last section discussed forces that shape the earth. This section describes landforms and bodies of water on the earth. You will also learn why people choose to live where they do.

Organizing Your ThoughtsUse the chart on the next page to help you take notes. Some

landforms are alike in certain ways. They are different in other ways. The chart shows pairs of landforms. For each pair, write the main difference between them.Reading Essentials and Study Guide 4


The earth has seven continents. These are North America, South America, Europe, Africa, Asia, Australia, and Antarctica. All have many land features, or landforms.6. What kinds of land features do you know about that are in the

United States?

5.

4.

3.

2.

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Main Difference

oceans and lakes

straits and channels

peninsulas and islands

valleys and trenches

plains and plateaus

Landform Pair


Types of LandformsMountains are huge towers of rock. Plates smashing together

made them. Volcanoes also make them. The world’s tallest mountain is Mt. Everest. It is in the Himalaya mountain ranges in Asia. Mt. Everest is 29,035 feet high. This is almost five and a half miles high!

Mountains have high peaks. Their sides are steep and rough. Hills are lower and rounded. Hills at the base of mountains are called foothills.

Plains and plateaus are mostly flat. The difference is their height above sea level, or elevation. Plains are low areas of flat land. Plateaus are higher areas of flat land. Some plateaus have cliffs on one side. Others have tall mountains around them.

Valleys lie between mountains and hills. A valley is lower than the land around it. Often, rivers are at the bottom of valleys. Canyons are low areas with steep sides. Rivers cut canyons through plateaus. The Grand Canyon is in Arizona. The Colorado River flowed over a plateau for millions of years. It cut through the rock to form the Grand Canyon.LOOKING AT THE EARTH


An isthmus is a narrow piece of land. It connects two larger pieces of land. A peninsula is land with water on three sides. Land with water on all sides is an island.

Landforms under the oceans are like those on land. A continental shelf is a plateau off each coast of a continent. It runs for several miles underwater. The shelf ends in a steep cliff. The cliff drops to the ocean floor.

The ocean floor has tall mountains. It also has deep valleys. Trenches are valleys on the ocean floor. They are the lowest spots on the earth’s crust. The Mariana Trench is the deepest one. If you placed Mt. Everest in the Mariana Trench, the mountain peak would still not reach the ocean’s surface.

People live on all types of landforms. Some live high in mountains. Others live in valleys. Some landforms are easier to live on than others.

People decide where to live for several reasons. One is climate. This is the average temperature and rainfall of a region. Another reason is resources. People live where they can get freshwater. They live where they can grow or catch food and raise animals. They look for places with useful supplies. For example, people use trees for building and they use oil for making energy. 7.What kinds of things make an area a good place to live?

Bodies of WaterAbout 70 percent of the earth’s surface is water. Most is salt

water. People and most animals cannot drink salt water. Only a small amount is drinkable freshwater.

The earth’s largest bodies of water are oceans. Oceans are made of salt water. Smaller bodies of salt water have land around them. Some are called seas, like the Mediterranean Sea. Others are called gulfs or bays.

Two types of bodies of water connect larger bodies of water. A strait is a narrow water passage between two pieces of land. A channel is a wider passage of water.

Bodies of freshwater appear on land. These are lakes, rivers, ponds, and streams. A river usually begins high in the mountains. This starting point is its source. At the other end is the river’s mouth. Here it emptiesReading Essentials and Study Guide 4


into another body of water. A river carries sand and soil from its banks. It drops this material at its mouth. In time, the sand and soil build up to form a delta.8.How is a lake different from a gulf?


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