1. Unit 4 Lesson 4 What Are Natural Resources?
Copyright © Houghton Mifflin Harcourt Publishing Company

2. Resources You Can Rely On
Unit 4 Lesson 4 What Are Natural Resources?
Resources You Can Rely On
Natural resources are materials found in nature that are used by living things.
Natural resources that can be replaced quickly are called renewable resources. These resources include air, water, trees, and sunlight.
The wise use of resources is called conservation.
Renewable resources must be conserved so that they are not used up.
Copyright © Houghton Mifflin Harcourt Publishing Company

3. Nonrenewable Resources
Unit 4 Lesson 4 What Are Natural Resources?
Nonrenewable Resources
Resources that aren’t replaced easily are called nonrenewable resources. Soil, rocks, minerals, fossil fuels, and ores are all nonrenewable resources.
Because they form so slowly, there are limited amounts of nonrenewable resources. These resources are used more quickly than they are naturally replaced.
Copyright © Houghton Mifflin Harcourt Publishing Company

4. Nonrenewable Resources
Unit 4 Lesson 4 What Are Natural Resources?
Nonrenewable Resources
Soil is a nonrenewable resource used by people to grow crops. If it is used improperly it can be washed away.
Fossil fuels, such as oil, coal, and natural gas, are burned to produce electricity or used to run different vehicles.
Copyright © Houghton Mifflin Harcourt Publishing Company

5. Nonrenewable Resources
Unit 4 Lesson 4 What Are Natural Resources?
Nonrenewable Resources
Rocks and minerals are used for many different things, from building materials to dyes for clothing.
A mineral is a nonliving solid with a crystal form.
A rock is a solid substance made up of one or more minerals.
An ore is a rock that contains valuable minerals.
Copyright © Houghton Mifflin Harcourt Publishing Company

6. Unit 4 Lesson 4 What Are Natural Resources?
From Coast to Coast
Mining is done to get valuable minerals, such as silver, iron, and copper.
Mining also takes place to get fossil fuels. Other mining gets rocks used to construct roads and buildings.
Some land is used for food production. Some farmers grow crops, such as corn, or raise cows that provide milk to make cream and cheese.
Copyright © Houghton Mifflin Harcourt Publishing Company

7. Unit 4 Lesson 4 What Are Natural Resources?
From Coast to Coast
Some land is used to produce green energy, or energy generated using renewable resources.
Wind farms, solar panels, and hydroelectric dams use wind, sunlight, and water to produce electricity.
Forests, or areas with large numbers of trees, provide lumber used to make furniture and paper and to build houses.
Copyright © Houghton Mifflin Harcourt Publishing Company

8. Unit 4 Lesson 4 What Are Natural Resources?
Flowing Down Slope
In the United States, water from 31 states drains into the Mississippi River, which makes this river system one of the largest watersheds in the world.
A watershed is all the land and water that drain into a river system.
The Mississippi River watershed is an important natural resource. It supplies drinking water to more than 50 cities. People also use water from this watershed to grow crops, for recreation, and for transportation.
Copyright © Houghton Mifflin Harcourt Publishing Company

9. Unit 4 Lesson 4 What Are Natural Resources?
Keeping It Clean
Pollution can harm natural resources such as air, water, and soil. Pollution also can harm plants and animals.
Recycling, reducing waste, and reusing materials are common ways to conserve natural resources.
Copyright © Houghton Mifflin Harcourt Publishing Company