KEY CONCEPT
Natural resources
support human activity.
BEFORE, you learned
NOW, you will learn
• Earth’s distant past is revealed
in rocks and fossils
• Layers of sedimentary rock
show relative ages
• Living things have inhabited
Earth for over 3 billion years
• What makes a natural resource
renewable or nonrenewable
• About benefits and costs of
using fossil fuels
• How people use natural
resources in modern life
VOCABULARY
THINK ABOUT
natural resource p. 147
renewable resource p. 148
nonrenewable
resource p. 148
fossil fuel p. 150
What resources do you
need the most?
Think about all the products you
use at school and at home—clothing,
books, video games, CDs, backpacks,
and other items.
Which ones do you use the most
often? What materials are these products made of? Plastic? Cloth? Metal?
What would you lose if one of these
materials, such as plastic, vanished
from Earth overnight?
Natural resources provide materials
and energy.
VOCABULARY
Use a four-square diagram
for the term natural resource
in your notebook.
For thousands of years, people have used natural resources to make
tools, build cities, heat their homes, and in general make their lives more
comfortable. A natural resource is any energy source, organism, or
substance found in nature that people use.
The four parts of the Earth system—atmosphere, hydrosphere,
biosphere, and geosphere—provide all the resources needed to sustain
human life. The atmosphere, for instance, provides the air you breathe
and the rain that helps living things grow. The hydrosphere contains all
of Earth’s waters in rivers, lakes, oceans, and underground. The biosphere and the geosphere are sources of food, fuel, clothing, and shelter.
Chapter 5: Natural Resources 147
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NOTE TAKING
A content frame can help
you take notes about the
costs and benefits of using
natural resources.
However, people also know that there are costs as well as benefits in
using natural resources. For example, burning coal produces heat but
also releases smoke that pollutes the air. When forests are cut down, the
soil beneath is exposed to the air. Wind and rain can strip away valuable
topsoil, making it harder for new trees to grow. The soil can choke
streams and rivers and kill fish and other animals living in the waters.
As you can see, using resources from one part of Earth’s system affects
all the other parts.
People are also concerned about saving natural resources. Some
resources, such as the water in a river or the wind used to turn a
windmill, are constantly being replaced. But others, such as oil, take
millions of years to form. If these resources are used faster than they
are replaced, they will run out. Today people are more aware of which
resources are renewable and which are nonrenewable.
check your reading
Summarize the costs and benefits of using natural resources.
Renewable Resources
The charts on page 149 list some of the most common resources people
use in modern life. As you might have guessed, sunlight, wind, water,
and trees and other plants are renewable. A renewable resource is a
natural resource that can be replaced in nature at about the same rate
it is used.
For example, a lumber company might plant a new tree for each
mature tree it cuts down. Over time, the forest will continue to have
the same number of trees. However, if the trees are cut down faster
than they can be replaced, even a renewable resource will run out.
Nonrenewable Resources
A nonrenewable resource is a natural resource that exists in a fixed
amount or that is used up faster than it can be replaced in nature.
This means the supply of any nonrenewable resource is limited.
In general, all resources produced by geologic forces—coal, natural gas,
oil, uranium—are nonrenewable. These resources form over millions
of years.
Today people are using coal, oil, and natural gas much faster than
they are forming in nature. As a result, these resources are becoming
more scarce and expensive. Many countries realize that they must
conserve their nonrenewable resources. Some, like the United States,
are developing alternative energy sources, such as solar and wind energy.
check your reading
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148 Unit: The Changing Earth
Compare and contrast renewable and nonrenewable resources.
Natural Resources
Natural resources can be classified as renewable and
nonrenewable resources.
Renewable Resources
Resource
Common Uses
Sunlight
power for solar cells and batteries, heating of homes and
businesses, and generating
electricity
Wind
power to move windmills
that pump water, grind grain,
and generate electricity
Water
power to generate electricity,
transportation with boats
and ships, drinking and
washing
Trees and
other plants
materials for furniture,
clothing, fuel, dyes,
medicines, paper, cardboard,
and generating electricity
Animal waste
material for fuels
Nonrenewable Resources
Resource
Common Uses
Coal
fuel to generate electricity,
chemicals for medicines and
consumer products
Oil
fuel for cars, airplanes, and
trucks; fuel for heating
and generating electricity;
chemicals for plastics, synthetic fabrics, medicines,
grease, and wax
Natural gas
fuel for heating, cooking,
and generating electricity
Uranium
fuel to generate electricity
Minerals and rocks
materials for coins, jewelry,
building, computer chips,
lasers, household products,
paint, and dyes
Read the common uses of each resource. Which of these resources are
used to generate electricity?
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Fossil fuels supply most of society’s energy.
Every time you turn on the air conditioner, a computer, or a microwave
oven, you use energy from fossil fuels. Millions of people depend on
these fuels—coal, oil, and natural gas—for electricity, heat, and fuel.
A fossil fuel is a nonrenewable energy source formed from ancient
plants and animals buried in Earth’s crust for millions of years. The
energy in such a fuel represents a form of stored sunlight, since ancient
organisms depended on the sun. The buried organisms form layers
at the bottom of oceans, ponds, and swamps. Over a long time, this
material is compressed and pushed deeper into Earth’s crust. High heat
and pressure change it chemically into coal, oil, and natural gas.
check your reading
Explain how fossil fuels are formed from ancient organisms.
Fossil Fuel Power Station
U.S. Energy Sources
Oil
Coal
Natural gas
Other
41%
25%
20%
14%
Smoke stack: Byproducts
of burning fuel are released
into the air.
Source: U.S. Department of Energy, 2000
Boiler: Heat from burning
fossil fuels boils the water
to produce steam.
Turbine: Steam
from the boiler
turns the turbines
Generator: Turbines
drive generators to
produce electricity.
Power
Lines
Fossil
fuel
source
Water is used to
cool the machinery.
Condenser: Steam
How does burning fossil fuels help to produce electricity?
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150 Unit: The Changing Earth
condenses into water, which
will return to the boiler.
Fossil fuels burn easily and produce a lot of heat. They are used to
run most of the power plants that generate electricity. As shown in the
diagram on page 150, heat from a burning fuel is used to change water
into steam. The steam turns a turbine. The turbine drives a generator
to produce electricity, which is carried through power lines to towns
and cities. Electricity runs nearly everything in modern life, from giant
factories to the smallest light in your home.
reading tip
Turbine is based on
the Latin turbo, which
means “spinning top.”
Generator is based on the
Latin generare,
which
means “to produce.”
But these resources also harm the environment. Burning fossil
fuels produces excess carbon dioxide, harmful acids, and other forms
of pollution. Most of this pollution comes from power plants and
fossil fuels burned by cars and other vehicles.
Coal
Coal is a solid fossil fuel formed underground from buried and decayed
plant material. As shown below, heat and pressure determine the type
of coal formed. The hardest coal makes the best energy source. It burns
hotter and much cleaner than softer coals. At one time, coal was the
main source of energy in the United States.
1
2
3
Swamp plants decay
and are compressed
to form peat.
Sediments bury the
peat, and rising pressure
and heat change it into
soft coal.
Over millions of years,
increasing pressure and
heat form harder coal.
4
It takes the longest time
and the greatest heat
and pressure to form
the hardest coal.
The world’s largest coal deposits are in the United States, Russia,
and China. People use surface mining and deep mining to obtain coal.
In surface mines, overlying rock is stripped away to expose the coal.
In deep mines, miners must go underground to dig out the coal.
Most of the world’s coal is used to fuel power plants and to run factories
that produce steel and cement.
When burned as a fuel, however, coal produces byproducts that
pollute air and water. Also, surface mining can destroy entire landscapes.
Coal dust in deep mines damages miners’ lungs. Yet reducing pollution,
restoring landscapes, and protecting miners cost millions of dollars.
Society faces a difficult choice—keep the cost of energy low or raise
the price to protect the environment and human health.
check your reading
What is the main use of coal?
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reading tip
Non- is a Latin prefix meaning “not.” Porous rock is
full of tiny cracks or holes.
Therefore, nonporous rock
is rock that does not have
tiny cracks or holes.
Oil and Natural Gas
Most oil and natural gas are trapped underground in porous rock.
Heat and pressure can push the oil and natural gas upward until they
reach a layer of nonporous rock, where they collect. As shown in the
illustration below, wells can be drilled through the nonporous rock to
bring the oil and natural gas to the surface. Major oil and natural gas
deposits are found under the oceans as well as on land.
check your reading
How is oil removed from layers of rock?
Recovered oil is transported by ships, trucks, and pipelines from the
wells to refineries. Refineries use heat to break down the oil into its different parts. Each part is used to make different products, from gasoline
and jet fuel to cleaning supplies and plastics. Oil and natural gas burn
at high temperatures, releasing energy. They are easily transported,
which makes them ideal fuels to heat homes and to power vehicles.
There are costs in using oil. When ships that transport oil are
damaged, they can spill millions of gallons into the environment.
These spills pollute coastlines and waterways, killing many plants
and animals. Cleaning up these spills costs governments millions of
dollars each year. Even after the cleanup, some of the oil will remain
in the environment for years.
Air pollution is another problem. Waste products from the
burning of gasoline, jet fuels, and diesel fuels react with sunlight
to produce smog—a foglike layer of air pollution. Some countries
have passed clean air laws to reduce this pollution. Yet smog
continues to be a problem in most cities.
check your reading
What are the benefits and costs of using oil?
Oil and Natural Gas Wells
Wells are drilled
through nonporous
rock to bring the oil
and gas to the surface.
Products from a Barrel of Oil
nonporous shale
Oil and gas are
trapped in porous
rock layers.
porous sandstone
Gasoline
Diesel and
heating fuel
Jet fuel
Other products
Gases
Asphalt
44%
26%
10%
9%
8%
3%
SOURCE: American Petroleum Institute, 2001
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152 Unit: The Changing Earth
Fossil Fuels
SKILL FOCUS
Why does an oil spill do so much harm?
Modeling
PROCEDURE
1
MATERIALS
Fill the pan about halfway with water. Using an eyedropper, carefully add
10 drops of oil in the middle of the pan. Rock the pan gently.
• vegetable oil
• large pan (at
least 22 cm)
• plastic-foam ball
(about 5 cm)
• eyedropper
2 Observe what happens to the drops of oil over the next 2 min.
Record your observations in your Science Notebook.
3 Place the plastic-foam ball in the oil slick, wait a few seconds, then carefully
lift the ball out again. Examine it and record your observations.
TIME
20 minutes
WHAT DO YOU THINK?
• What happened when the drops of oil came in contact with the water?
• What might happen to an animal that swims through spilled oil?
CHALLENGE Think of a way to clean up the oil slick
on the water. Discuss your ideas with your teacher
before you test your cleaning method.
Fossil fuels, minerals, and plants supply
materials for modern products.
Many of the products you use come from fossil fuels. For example, oil
is broken down into different chemicals used to make plastics. Plastic
materials can be easily shaped, colored, and formed. They are used in
electronic and computer equipment, in packaging, in cars and airplanes,
and in such personal items as your shoes, toothbrush, and comb.
Minerals are found in cars and airplanes, tools, wires, computer
chips, and probably your chair. Minerals such as limestone, gypsum,
sand, and salt are used to make building materials and cement. In the
United States, it takes 9,720 kilograms (20,000 lbs) of minerals every
year to make the products used by just one person.
Plants are used to make another large group of products. For centuries people have used wood to build homes and to make furniture,
household utensils, and different types of paper. Plants are also rich
sources of dyes, fibers, and medicines. The plant indigo, for example,
has been used to dye fabrics since Roman times.
These products benefit people’s lives, but they also have drawbacks.
Fossil fuels must be burned to generate power for the factories and
businesses that produce these products. Factory waste can pollute air,
Chapter 5: Natural Resources 153
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Consumer Products
Thousands of everyday products are made from natural resources.
Fossil Fuels
Minerals and Rocks
The U.S. Treasury uses zinc, copper, and
nickel to mint over 14 billion coins a year.
Gold and silver are used in special coins.
Trees and Other Plants
Fossil fuels are used to make thousands of products
from aspirin to zippers. For example, oil-based plastics
are used to make this motocross rider’s safety helmet,
suit, gloves, and boots. Gasoline powers the motorbike.
Each year, the United States produces
about 400 billion square feet of corrugated
cardboard used to make boxes of all sizes.
water, and soil. Even making computer chips can be a problem.
So much water is needed to clean the chips during manufacture
that local water supplies may be reduced.
To maintain modern life and to protect the planet, people must
use natural resources wisely. In the next section you will read about
ways for every person to conserve resources and reduce pollution.
KEY CONCEPTS
CRITICAL THINKING
1. Define renewable resource
and nonrenewable resource.
Give four examples of each
type of resource.
4. Infer Why do you think people
are willing to accept the costs
as well as the benefits of using
fossil fuels?
2. List three advantages and
three disadvantages of using
fossil fuels.
5. Predict If supplies of coal, oil,
and natural gas ran out tomorrow, what are some of the ways
your life would change?
3. In what ways are natural
resources used to make people’s
lives more comfortable?
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154 Unit: The Changing Earth
CHALLENGE
6. Apply Suppose you are lost in
the woods, miles from any city
or town. You have some dried
food and matches but no other
supplies. What natural resources
might you use to survive until
you are found?