Earth ScienceEarth Science GenreGenre Comprehension SkillComprehension Skill Text FeaturesText Features Science ContentScience Content Nonfi ctionNonfi ction Compare andCompare and • Captions• Captions Rocks and SoilRocks and Soil ContrastContrast • Charts• Charts • Labels• Labels • Glossary• Glossary Scott Foresman Science 3.7Scott Foresman Science 3.7 ì<(sk$m)=bdicgf<ì<(sk$m)=bdicgf<ISBNISBN 0-328-13826-60-328-13826-6 +^-Ä-U-Ä-U+^-Ä-U-Ä-U by Lorrie Oestreicherby Lorrie Oestreicher
Vocabulary What did you learn?Rocks and Soil decay 1. How are metamorphic rocks formed? igneous rock 2. Name some different ways minerals are used.by Lorrie Oestreicher loam 3. What are the three layers of soil? metamorphic rock 4. In this book you have read mineral about minerals. Write to explain how scientists identify minerals. Use details from the book. nutrient 5. Compare and Contrast Compare and rock contrast ways igneous rock forms and the effects sedimentary rock these ways have on the rock. soil 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: ©Mark Newman/Lonely Planet Images; Title Page: ©Douglas Peebles/Corbis; 2 ©J. A. Kraulis/ Masterfile Corporation; 4 (B) ©Douglas Peebles/Corbis, (CL) ©DK Images; 6 (BR) ©DK Images, (CL) Royal Museum of Scotland/©DK Images, (TR) Getty Images; 7 (T, CC) ©DK Images; 8 ©DK Images; 10 (CL) ©DK Images, (TL) ©M. Claye/Jacana Scientific Control/Photo Researchers, Inc., (CCT) ©Ross Frid/Visuals Unlimited, (CC) Getty Images, (CCB) ©Royalty-Free/Corbis, (CLB, BL) ©DK Images; 12 (CC) ©G. I. Bernard/Animals Animals/Earth Scenes,(CR) ©Jeremy Burgess/Science Photo Library/Photo Researchers, Inc., (BR) ©Dr. Parvinder Sethi; 13 ©Peter Hulme; Ecoscene/Corbis ISBN: 0-328-13826-6 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
How do rocks form? Rocks can be many different colors. The texture of the rock is the size of the bits of minerals that make up Rocks the rock. Is it smooth to touch? Is it rough? Does it feel scratchy? Does it feel hard or soft? The grains of the Rock is found in nature. Rock is solid. It is minerals that make up the rock determine how it feels. nonliving matter. All rocks are made of one or more In some rocks the bits of minerals are so small you minerals. A mineral is a natural material that forms can’t see them easily. from nonliving matter. You can tell rocks apart by their properties. Physical properties are what we see by looking at a rock. These properties include the rock’s color, the minerals in the rock, and the texture. 2 3
Rock Groups Sediment is material that settles Rocks are put into three different groups. to the bottom of rivers, lakes, and Igneous rock forms from minerals and gases oceans. Little bits of rock make up melted together. Sometimes this mixture cools slowly sediment. After a very long time, and hardens below ground. Then the mineral grains layers of these bits of rock pile up may be easy to see. Other times, the red-hot mixture and stick together. Over time, the cools quickly above ground, or in the ocean. Then the layers get pressed together, and mineral grains may be too small to see. they form sedimentary rock. Sedimentary rock forms in layers. It forms one layer at a time. Igneous rock 4 5
Fossil remains can be found in sedimentary rocks. The word metamorphic means “to change form.” Extinct plants and animals were buried in sand and Metamorphic rock is rock that is changed by heat, mud. This hardened into rock. Layers of rocks with pressure, or both into another kind of rock. Shale is fossils show the history of life. a sedimentary rock. When shale gets buried deep underground, heat and pressure change its minerals. The shale becomes slate, a metamorphic rock. Shale changes to slate. These are all fossils of ancient animals. 6 7
What are minerals? Another test to identify minerals checks their hardness. The hardest mineral is diamond. No Identifying Minerals mineral can scratch it except another diamond. Some minerals can be identified by how they look. Color is a property of minerals. Some minerals come Gold sometimes comes in nuggets. Other minerals can in many different colors. Quartz can be pink, purple, be identified by how they feel, smell, or taste. yellow, brown, white, or black. Some minerals only come in one color. Scientists use many tests to Properties of Minerals help identify minerals. Rub a Mineral Mineral Color Luster Streak Hardness mineral across a rough surface. MicaMica It may leave a streak mark or Mica breaks black, pearly on white can be powder. Even if a mineral comes into flaky gray, surfaces scratched pieces green, with a knife in different colors, it will always when struck. violet leave the same color streak mark. Minerals also have luster. This property shows how a mineral MolybdeniteMolybdenite This mineral is silvery metallic bluish can be reflects light. one of the gray scratched strongest and with a most commonly fingernail used heat-resistant metals. CrocoiteCrocoite Much of this reddish- very orange- can be mineral orange shiny yellow scratched comes from with a Australia. coin 8 9
How We Use Minerals Every day we use minerals. Most toothpaste Halite The mineral halite is crushed contains fluoride that helps fight cavities. Fluoride and then ground up. We use it to flavor and preserve food. comes from the mineral fluorite. The windows in your (We know this mineral as table salt.) house are made from the minerals quartz, soda, ash, and limestone. The salt in your food is the mineral halite. The fork and spoon you eat with are made Copper The mineral copper is found in igneous rock. The rocks are from minerals. We use minerals for almost everything. mined from the ground. When the rocks are crushed and heated, the copper becomes Minerals Keep Us Healthy separated from the rock. Then the copper can be made into objects, such as pots and pans. Our bodies need minerals to stay healthy. Minerals help form bones and skin. Minerals also help release Fluorite The mineral fluorite is found in many rocks, such as granite. energy and move it through our bodies. The rocks are crushed and the fluorite is separated out. Then it Many of the minerals we need are found in plants. is used to make many products, such as toothpaste. Green leafy vegetables, such as spinach, contain calcium. Iron is found in fruit and green vegetables. Sodium is a mineral found in celery. Potassium is Lead Lead is found in a mineral known as galena. The rocks found in fruits. Phosphorus is found in green beans. are crushed and heated to produce lead. Lead is put into Minerals are in almost everything we eat. aprons, such as the ones shown, to protect people while X-ray pictures are taken. Iron Iron is found in the rock called hematite. The rocks are crushed and heated. Then iron in the melted material is separated out. Iron is mixed with other materials to make steel. Steel is used for many tools and machines. 10 11
Why is soil important? Soil Layers Soil has three different layers. The layers Parts of Soil are topsoil, subsoil, and bedrock. The layers may look different in different Soil is a thin layer of loose material. It covers most places. of Earth’s land. Soil takes a long time to develop. It has Topsoil the material plants need to grow. Topsoil is the first layer. It has rock pieces Soil is more than just bits of mixed with decayed parts of plant and animal remains. The decayed remains are rock. It holds water. It holds called humus. Humus has a lot of what material that was once living. plants need to grow. Living things in soil break down what is left of plants and animals after they die. This Subsoil process is called decay. Decay Subsoil is the soil under topsoil. It is lighter releases nutrients into the soil. Earthworms mix up in color. It has less humus. It has pieces the topsoil as they of broken rocks. The roots of trees grow Some minerals release nutrients dig through it. That down into subsoil. Water from rain may improves the soil. soak down into this layer. too. Plants need nutrients to grow. We depend on topsoil to grow our food. Bedrock Soil must pack down hard As this rock breaks down, it slowly turns and stay firm so that houses into new soil over many, many years. built on it don’t shift. 12 13
Comparing Soils All soil has the same four ingredients. Most of Soils can be different. Sand, silt, and clay particles the soil is made up of weathered rocks. These rocks are found in soil. Sand particles are the largest. They have minerals. Humus makes up soil too. It is a very have large spaces between them. Water runs quickly important part of soil. Air and water fill in the spaces through sandy soil. Silt has medium-sized particles. Its between rocks and humus. spaces are not as large as those in sand. Silty soil holds Loam is a good soil for growing plants. It contains water well. Clay particles are the smallest. Once clay sand, silt, clay, humus, and air. Plants can soak up soil gets wet, the particles hold tightly together. water easily from loam. Sandy soil feels rough and gritty. How do you think silt feels? Wet clay feels smooth and sticky. 14 15
VocabularyGlossary What did you learn? decaydecay the breaking down of plant or 1. How are metamorphic rocks formed? igneous rock animal matter 2. Name some different ways minerals are used. igneous rockloam rock that is formed from a 3. What are the three layers of soil? red-hot mixture of melted metamorphic rock minerals and gases 4. In this book you have read mineral about minerals. Write to explain how scientists loam soil that contains sand, silt, identify minerals. Use details from the book. nutrient clay, air, water, and humus 5. Compare and Contrast Compare and metamorphic rockrock rock that is formed from other contrast ways igneous rock forms and the effects rocks by heat, pressure, or these ways have on the rock. sedimentary rock both soil mineral natural substances that form rocks nutrient a thing needed by plants to 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 itsgrow strong and healthy 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: ©Mark Newman/Lonely Planet Images; Title Page: ©Douglas Peebles/Corbis; 2 ©J. A. Kraulis/rock natural, solid, nonliving Masterfile Corporation; 4 (B) ©Douglas Peebles/Corbis, (CL) ©DK Images; 6 (BR) ©DK Images, (CL) Royal Museum of Scotland/©DK Images, (TR) Getty Images; 7 (T, CC) ©DK Images; 8 ©DK Images; 10 (CL) ©DK Images, (TL) ©M. Claye/Jacana Scientific Control/Photo Researchers, Inc., (CCT) ©Ross Frid/Visualsmaterial found in Earth Unlimited, (CC) Getty Images, (CCB) ©Royalty-Free/Corbis, (CLB, BL) ©DK Images; 12 (CC) ©G. I. Bernard/Animals Animals/Earth Scenes,(CR) ©Jeremy Burgess/Science Photo Library/Photo Researchers, Inc., (BR) ©Dr. Parvinder Sethi; 13 ©Peter Hulme; Ecoscene/Corbissedimentary rock rock that is formed by layers ISBN: 0-328-13826-6 of sediment that are pressed Copyright © Pearson Education, Inc. together All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher priorsoil loose material that covers to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. Formost of Earth’s land 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 16
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