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Copyright © by Harcourt, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to School Permissions and Copyrights, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887-6777. Fax: 407-345-2418. HARCOURT and the Harcourt Logo are trademarks of Harcourt, Inc., registered in the United States of America and/or other jurisdictions. Printed in the United States of America ISBN-13: 978-0-15-349156-6 ISBN-10: 0-15-349156-6 1 2 3 4 5 6 7 8 9 10 179 15 14 13 12 11 10 09 08 07 06 If you have received these materials as examination copies free of charge, Harcourt School Publishers retains title to the materials and they may not be resold. Resale of examination copies is strictly prohibited and is illegal. Possession of this publication in print format does not entitle users to convert this publication, or any portion of it, into electronic format.
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Earth Materials Lessons 1–3 Rocks and Minerals . . . . . . .2 Comparing Minerals . . . . . .4 Wind and Rain Cause Weathering . . . . . .6 Water Causes Weathering .7 Plants Cause Weathering . .8 Things in the Air Cause Weathering . . . . . .9 Soil . . . . . . . . . . . . . . . . . . .10 Kinds of Soil . . . . . . . . . . . .12 Soil for Growing Things . .14
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Rocks and Minerals Mountains are made of rock. Rock is a hard, solid material. Some rocks are very big. Some are tiny. 2
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rocks mineral Rock is made up of minerals. Some rocks have only one mineral. Most rocks have two or more minerals. 3
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Comparing Minerals Minerals have different properties. Minerals are different colors. Some minerals are shiny. Some are not. Minerals have different textures. Some are rough. Some are smooth. Mineral Color 4
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Mineral Hardness talc diamond Some minerals are harder than others. A harder mineral will scratch a softer one. A diamond is the hardest mineral. It can scratch talc, the softest mineral. 5
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Wind and Rain Cause Weathering weathered rock Wind breaks rock into pieces. Rain also breaks down rock. This is weathering. Weathering changes all of Earth’s rock. 6
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Water Causes Weathering rock cracked by freezing water Water may freeze in the cracks of rock. When water freezes, it turns into ice. Ice takes up more space than water. So, the ice makes the cracks bigger. After a while the rock breaks into pieces. 7
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Plants Cause Weathering rock cracked by roots The roots of some plants are strong. They may push into the cracks in rocks. Little by little they make the cracks bigger. The roots of this tree have cracked the rock. 8
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Things in the Air Cause Weathering Water in the air mixes with other things. The mixture causes weathering. Weathering may change the color of rock. It may eat away minerals in the rock. weathered statue made of rock 9
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Soil is made of bits of rock and other material. Most soils have parts of dead plants in them. The dead plants rot and fall apart. The rotted bits become part of the soil. Parts of dead animals may also be in soil. The plant and animal matter is called humus. Worms mix up soil as they move through it. 11
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Kinds of Soil Clay • smooth when dry • sticky when wet • holds a lot of water Silt • smooth • feels like powder • does not hold water well There are many kinds of soil. Different soils look different. Some are light in color. Some are dark. 12
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Humus • soft, crumbly • holds a lot of water Sand • rough, grainy • does not hold water well Soils also feel different. Some soils are smooth. Some are grainy. 13
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Soil f or Growing Things corn in soil with clay lettuce in soil with humus Soil helps plants get the water they need. Some soil holds water better than others. Soil with a lot of humus holds water well. 14
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cotton in silt plants in sand Soil helps plants get the nutrients they need. Different soils have different nutrients. Different plants grow well in different soils. 15
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Vocabulary freeze, p. 7 humus, p. 11 mineral, p. 3 property, p. 4 rock, p. 2 rot, p. 11 soil, p. 10 texture, p. 4 water, p. 7 weathering, p. 6 16
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Think About the Reading 1. What new ideas do you have after reading this book? 2. How can you learn more about your new ideas? Hands-On Activity 1. Collect rocks of different colors and sizes. 2. Compare and sort the rocks by color. Then sort them by size. Think of another way to sort them. School-Home Connection Tell a family member what you have read about rocks and soil. Talk with the family member about the rocks and soil in your area.
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