chapter resources for differentiated instruction weathering … · · 2012-04-09chapter resources...

Chapter Resources for Differentiated Instruction Weathering and Soil

Title Page Lesson 1 Lesson 2 Level

Get Ready to Read 1 all students

Quick Vocabulary 3 all students

Student Lab Safety Form 5 all students

Launch Lab 8 28 all students

Content Vocabulary ELL 9 29 all students

Lesson Outline ELL 10 30 all students

MiniLab 12 32 all students

Content Practice A 13 33 AL OL BL

Content Practice B 14 34 AL OL BL

Language Arts Support 35 all students

Math Skills 15 all students

School to Home 16 37 all students

Key Concept Builders 17 38 AL OL BL

Enrichment 21 42 all students

Challenge 22 43 AL OL BL

Lesson Quiz A 25 44 AL OL BL

Lesson Quiz B 26 45 AL OL BL

Skill Practice 23 all students

Lab A 46–48 AL OL BL

Lab B 49–51 AL OL BL

Lab C 52 AL OL BL

Chapter Key Concepts Builder 53 AL OL BL

Chapter Test A 54–56 AL OL BL

Chapter Test B 57–59 AL OL BL

Chapter Test C 60–62 AL OL BL

Answers (with Lesson Outlines) T2–T13

AL Approaching Level OL On Level BL Beyond Level ELL English-Language Learner

Teacher evaluation will determine which activities to use or modify to meet any ELL student’s proficiency level.

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Copyright © by The McGraw-Hill Companies, Inc. All rights reserved. Permission is granted to reproduce the material contained herein on the condition that such materials be reproduced only for classroom use; be provided to students, teachers, and families without charge; and be used solely in conjunction with the Glencoe Middle School Science program. Any other reproduction, for sale or other use, is expressly prohibited.

Send all inquiries to:Glencoe/McGraw-Hill8787 Orion PlaceColumbus, OH 43240-4027

ISBN: 978-0-07-891438-6MHID: 0-07-891438-8

Printed in the United States of America.

1 2 3 4 5 6 7 8 9 10 MAL 15 14 13 12 11 10

page 39: Matthew Ward/Getty Images

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Weathering and Soil iii

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iii

Title Frequency Overview Appropriate For

Get Ready to Read: What do

you think?

1/Chapter

Using the Get Ready to Read anticipation guide in the Student Edition? This page matches the anticipation guide in the Student Edition. Students can complete this at the beginning of a chapter and check their responses at the end.

all students

Quick Vocabulary

1/Chapter

Need some options to preteach vocabulary and help students with vocabulary development ? By folding the Quick Vocabulary sheet in half, students will have an easy reference tool. Lesson vocabulary, along with academic vocabulary, review vocabulary, or multiple-meaning words, are listed and defined. Students can add other words that they need to remember as well.

all students

Student Lab Safety Form

1/Chapter

Need a standard lab safety form? Each FastFile includes this form that students can complete prior to each lab. Students indicate that they understand all aspects of the lab. There is a place for the student and you to sign it.

all students

Launch Lab 1/Lesson

Want a lab recording page for Student Edition Launch Labs ? Each recording page matches the Student Edition Launch Labs, so students do not need to use their textbooks in the lab.

all students

Content Vocabulary*

1/Lesson

Want to help students who need more vocabulary practice? Content Vocabulary pages provide review and reinforcement activities. Use these pages to help students master content terms.

all students

Lesson Outline*

1/Lesson

Want an outline of the chapter for a substitute teacher, for absent students, or for students to use for review ? Lesson outlines follow the head and subhead structure of the Lesson, emphasizing the major content objectives. They can be used in many ways. In addition to those listed above, they can help you organize teaching notes and accompany student reading.

all students

MiniLab 1/Lesson

Want a lab recording page for Student Edition MiniLabs ? This recording page matches the Student Edition MiniLab, so students do not need to use their textbooks in the lab.

all students

AL Approaching Level OL On Level BL Beyond Level * ELL English-Language Learner


To The TeacherThis book contains reproducible pages that support the Student Edition. Descriptions and frequencies of these resources are listed in the table that follows.

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iv Weathering and Soil

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Content Practice

(Leveled)1/Lesson

Need more options for content review? Content Practice A is designed to help students who have difficulties learning and understanding the vocabulary and Key Concepts of each lesson:

• Form A—helps struggling students grasp lesson content

• Form B—provides on-level and beyond-level reinforcement of lesson content

AL AL AL

AL OL BL

Language Arts

Support1/Chapter

Looking for a way to help students build reading and writing skills in science? Language Arts Support pages provide practice using vocabulary, language structure clues, and writing skills with science content.

all students

Math Skills 1/ChapterWant help for students who need to practice math skills ? This page provides additional practice of the Math Skill in the Student Edition.

all students

School to Home

1/Lesson

Looking for a way to help students with the content ? The School to Home page provides support for a home-learning partner to help a student better understand the Big Idea of a chapter.

all students

Key Concept Builders

4/Lesson

Have students who need more practice with Key Concepts ? Key Concept Builders present the content in a context different from the Student Edition. These pages can be used whenever a student is struggling with any of the lesson’s Key Concepts.

AL AL AL

Enrichment 1/Lesson

Looking for ways to help students to broaden their understanding of lesson concepts ? Use Enrichment pages to further explore information and Key Concepts introduced in a lesson.

all students

Challenge 1/Lesson

Want to motivate the independent learner ? The Challenge activity extends information in the Student Edition and challenges a student’s abilities. The activity can be completed in class or at home.

AL AL BL

Lesson Quiz

(Leveled)1/Lesson

Need options to evaluate students after each lesson? These quizzes are developed around the Key Concepts of a lesson:

• Quiz A—provides more guided questions

• Quiz B—provides more short-answer and completion questions

AL

AL OL BL



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Weathering and Soil v

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Skill Practice

1/Chapter

Need a lab recording page for the Skill Practice? This corresponds to the Skill Practice in the Student Edition. Write-on lines are included for answers. Tables/charts/graphs are included for recording observations, or space is provided for drawing tables/charts/graphs. Students do not need to use their textbooks in the lab.

all students

Lab (Leveled)

1/Chapter

Want leveled lab recording pages for the Lab in the Student Edition? These pages provide leveled versions of the Student Edition Lab. Write-on lines are included for answers. Tables/charts/graphs are often included for recording observations, or space is provided for creating tables/charts/graphs:

• Version A—This version follows the student edition lab but each step of the procedure is broken down sentence by sentence. Included are check-off boxes that provide easier processing for struggling learners.

• Version B—This version is the student edition lab.

• Version C—This version is designed to be a challenge for independent learners. Students must complete version B before doing version C.

AL AL AL

AL OL BL

AL AL BL

Chapter Key Concepts

Builder1/Chapter

Have students who need more practice with Key Concepts related to the Big Idea? This practice page is designed to reinforce chapter content for struggling students before they take the chapter test.

AL AL AL

Chapter Test

(Leveled)1/Chapter

Need options to assess each student according to his or her abilities ? These leveled chapter tests accommodate all students:

• Version A—provides students with more guided questions

• Version B—more short-answer and completion questions

• Version C—challenges students with more difficult and open-ended questions

AL AL AL

AL OL AL

AL AL BL

Teacher Pages

Want all the answers in one place? These pages contain the answers for all the practice pages.



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Weathering and Soil 1

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Name Date Class

Weathering and SoilWhat do you think?Before you read, decide if you agree or disagree with each of these statements. On the line before each statement, place an A if you agree or a D if you disagree. As you read this chapter, see if you change your mind about any of the statements.

Before You Read Statements After You

Read

1. Any two rocks weather at the same rate.

2. Humans are the main cause of weathering.

3. Plants can break rocks into smaller pieces.

4. Air and water are present in soil.

5. Soil that is 1,000 years old is young soil.

6. Soil is the same in all locations.

What have you learned?After you read each lesson, return to this worksheet to see if you have changed your mind about any of the statements related to that lesson. Place a C after each statement that is correct or an I for those that are incorrect.

Get Ready to Read

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Name Date Class

Quick Vocabulary

Lesson 1

chemical weathering processes by which the materials in a rock are changed into new materials

environment physical, chemical, and biotic factors acting in a community

mechanical weathering processes by which rock is broken into smaller pieces

oxidation cause of chemical weathering; combines the element oxygen with other elements or molecules

weathering mechanical and chemical processes that change objects on Earth’s surface over time

Lesson 2

biota all the organisms living in a region

climate average weather of an area

decomposition process that changes once-living material into organic matter

horizon layer of soil formed from the movement of the products of weathering

organic matter remains of something that was once alive

parent material starting material—rock or sediment—that weathers and forms soil

pore small hole or space in soil

sediment rock material that has been broken down or dissolved in water

soil mixture of weathered rock, rock fragments, decayed organic matter, water, and air

topography shape and steepness of the landscape

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Student Name: Date:

Lab/Activity Title:

• Carefully read the entire lab and answer the following questions.

• Return this completed and signed safety form to your teacher to initial before you begin the lab/activity.

1. Describe what you will be doing during this lab/activity. Ask your teacher any questions you might have regarding the lab/activity.

2. Will you be working alone, with a partner, or with a group? (Circle one.)

3. What safety precautions should you take while doing this lab/activity?

4. Write any steps in the procedure, additional safety concerns, or lab safety symbols that you do not understand.

Student Signature

Date of Approval

Teacher Approval Initials

Student Lab/Activity Safety Form

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Student Labs and Activities Page Appropriate For:

Launch Lab 8 all students

Content Vocabulary ELL 9 all students

Lesson Outline ELL 10 all students

MiniLab 12 all students

Content Practice A 13 AL AL AL

Content Practice B 14 AL OL BL

Math Skills 15 all students

School to Home 16 all students

Key Concept Builders 17 AL AL AL

Enrichment 21 all students

Challenge 22 AL AL BL

Skill Practice 23 all students

Assessment

Lesson Quiz A 25 AL AL AL

Lesson Quiz B 26 AL OL BL

Teacher Support

Answers (with Lesson Outlines) T2



Lesson 1 | Weathering

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8 Weathering and Soil

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How can rocks be broken down?Have you ever looked at the rocks in a stream? What makes some rocks look different from other rocks?

Procedure

Launch Lab LESSON 1: 10 minutes

Data and Observations

Think About This 1. Compare and contrast the “rocks” from each cup.

2. Key Concept What do you think caused your “rocks” to change?

1. Read and complete a lab safety form.

2. Obtain 12 pieces of candy-coated chocolate candies. Put four of them in a plastic cup. Place the rest into a container with a lid.

3. Fasten the lid tightly. Shake the container vigorously 300 times.

4. Remove about half of the pieces. Place them in another plastic cup.

5. Replace the lid, and shake the container 300 more times. Remove the remaining “rocks” and place them in another cup. Record your observations below.

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WeatheringDirections: An analogy is a relationship between two pairs of words. An analogy can be written in the following manner: a is to b as c is to d. For example, apple is to fruit as celery is to vegetable. In the analogies that follow, one of the words is missing. On each line, write the term from the word bank that correctly completes each analogy.

chemical weathering environment mechanical weathering

oxidation weathering

1. Ice wedging is to mechanical weathering as is to chemical weathering.

2. is to increased surface area as chemical weathering is to changed minerals.

3. Weathering is to water and temperature as is to physical, chemical, and biotic factors.

4. Acid rain is to as abrasion is to mechanical weathering.

5. Chemical and mechanical are to as rain and snow are to precipitation.

Content Vocabulary LESSON 1



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WeatheringA. Weathering and Its Effects

1. The chemical and physical processes that change objects on Earth’s surface over

time are called .

2. Over thousands of years, breaks up rocks into smaller pieces.

B. Mechanical Weathering

1. During , physical processes break rocks into smaller pieces.

2. Mechanical weathering does not change the of the rock.

3. When mechanical weathering breaks a large rock into smaller pieces, the total

of the rock increases.

4. Between sandy and clay soils, soil holds more water and nutrients because it consists of smaller particles that have more surface area.

5. In , water enters cracks in rocks and freezes. Water

when it freezes and makes the cracks larger.

6. Grinding rock away by friction or impact is called .

7. growing in a crack in a rock and animals burrowing through loose rock can cause mechanical weathering.

C. Chemical Weathering

1. During , the materials that make up rocks are changed into new materials.

2. Water is an important agent of weathering because

most substances in water.

3. A(n) is a more powerful weathering agent than water.

a. The measure of acidity is called .

b. An acid has a pH less than .

c. Rain weathers rock because rain is slightly .

d. rain contains pollutants that make its pH less than 5.

Lesson Outline LESSON 1



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Lesson Outline continued

4. Oxygen combines with other elements or molecules

during .

a. Most oxygen used in oxidation comes from the .

b. The product of oxidation is a(n) .

c. Oxides are useful because they form , which people use to obtain metals.

d. The part of a rock oxidizes the most because it has more contact with oxygen in the air.

D. What affects weathering rates?

1. Mechanical and chemical weathering depend on and temperature.

a. Mechanical weathering occurs fastest in areas that have a lot of

changes.

b. Chemical weathering is fastest where the climate is warm

and .

c. Overall, weathering occurs fastest in regions near the .

2. The type of also affects how fast weathering occurs. The

most easily weathered in a rock determines how quickly the rock weathers.



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How are rocks weathered?Chemical weathering can be caused by weak acids. These acids react with minerals in the rock and produce new substances.

Procedure

MiniLab LESSON 1: 20 minutes


Analyze and Conclude 1. Recognize Cause and Effect Which substance reacted with the rock? How do you

know a reaction occurred?

2. Key Concept What might happen to rocks exposed to such a substance in the environment?

1. Read and complete a lab safety form.

2. Use a magnifying lens to carefully examine the rocks provided by your teacher. Note details such as color, texture, and size of grains.

3. Use a thin-stem pipette to place several drops of water on each rock.

4. Observe what happens to each rock. Record your observations in the Data and Observations section below.

5. Use the pipette to place several drops of diluted hydrochloric acid on the each rock. Again, record your observations.



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Name Date Class

Content Practice A LESSON 1

WeatheringDirections: Complete this concept map by choosing statements and writing them in the correct spaces.

Rock and water grind other rock.

Pollutants dissolve in water.

Animals burrow into soil.

Intense temperature causes rocks to expand.

1. Mechanical weathering

Weathering

2. Chemical weathering

Ice expands cracks in rock.

Molecules combine and form oxides.

Plants cause rocks to crumble.



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WeatheringDirections: Complete the chart by choosing terms from the word bank and writing them in the correct spaces. Then finish each sentence.

abrasion acid rain animals

intense temperatures ice wedging normal rain

oxidation plants

Mechanical Weathering Chemical Weathering

1. cause(s) weathering

because .

6. is the process that

combines .


because .

7. has a pH of about 5.6

and can cause .


because .

8. has a pH of 4.5 or less

and causes .


because .


because .

Directions: Respond to each statement on the lines provided. Use complete sentences.

9. Define weathering.

10. Explain the effects of mechanical weathering.

11. Explain the effects of chemical weathering.

Content Practice B LESSON 1



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Name Date Class

Use GeometryThe area (A) of a rectangle equals length (l ) times width (w). This is shown by the formula A = l × w. For a rectangular solid, the total surface area (SA) equals the sum of the areas of all six surfaces. Area is measured in square units, such as square centimeters (cm2).

A rectangular block of stone has a length of 8 cm, a width of 2 cm, and a height of 10 cm. What is its surface area?

Step 1 Find the areas of the six surfaces. top and bottom = 8 cm × 2 cm = 16 cm2

front and back = 10 cm × 8 cm = 80 cm2

right and left sides = 2 cm × 10 cm = 20 cm2

Step 2 Add the areas of the six surfaces. top + bottom + front + back + right side + left side 16 + 16 + 80 + 80 + 20 + 20

= 232

The stone has a surface area of 232 cm2.

Practice

Math Skills LESSON 1

1. A rectangular block of stone has a length of 7 cm, a width of 3 cm, and a height of 10 cm. What is the surface area of the stone?

2. A rectangular block of stone has a length of 9 cm, a width of 4 cm, and a height of 12 cm. What is the surface area of the stone?

3. A rectangular block of stone has a length of 9 cm, a width of 3 cm, and a height of 5.5 cm. What is the surface area of the stone?

4. A rectangular block of stone has a length of 10 cm, a width of 3 cm, and a height of 15 cm. What is the volume of the stone?

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School to Home LESSON 1

Weathering

Did you know?Some of the world’s best-known structures have fallen victim to weathering. Weathering has worn down the stones on the statues on Easter Island and on the pyramids in Egypt. Structures such as the Eiffel Tower, the Taj Mahal, and the Statue of Liberty have been weathered by acid rain and other chemicals in the air.

For this activity, you will first find an example of mechanical weathering in your neighborhood. Then you will find an example of chemical weathering. Use the chart below to record data on the examples of weathering you find.

Object Description Type of Weathering

1. How did you identify your first example as mechanical weathering?

2. How did you identify your second example as chemical weathering?

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Name Date Class

LESSON 1

WeatheringKey Concept How does weather break down or change rock?

Directions: Use the clues and the terms listed below to complete the puzzle.

abrasion acid acid rain burrowing

chemical weathering crumbling ice wedging oxide

pH surface area

Key Concept Builder

1

2 3

10

9

4 5

6

7 8

CluesAcross 2. weathering caused by grinding away

at rock

5. what animals do that breaks down rock

7. the process that changes minerals into new minerals

9. weathering caused by plants and animals

10. rain with a pH of 4.5 or less

Down 1. weathering caused by water that freezes

3. all the space on the surface plane of an object

4. the product of oxidation

6. a measure of acidity

8. anything with a pH between 0 and 7

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Name Date Class

Weathering Key Concept How do mechanical processes break rocks into smaller pieces?

Directions: Respond to each statement in the space provided.

Mechanical Weathering

Cause Effect

1. Draw a picture showing ice wedging.

2. Explain how ice wedging causes weathering.

3. Draw a picture showing abrasion.

4. Explain how abrasion causes weathering.

5. Draw a picture showing how plants cause mechanical weathering.

6. Explain how plants cause weathering.

7. Draw a picture showing how animals cause mechanical weathering.

8. Explain how animals cause weathering.

Key Concept Builder LESSON 1



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Name Date Class

WeatheringKey Concept How do mechanical processes break rocks into smaller pieces?

Directions: Answer each question and explain its importance in the space provided.

Mechanical Weathering Answer Why It Is Important

1. What does mechanical weathering do?

2. How long does it take for the effects of mechanical weathering to be noticeable in rocks?

3. What happens to the surface area of rock as it breaks apart?

4. What is the sequence of events in ice wedging?

5. What is the sequence of events in abrasion?

6. What is the sequence of events in weathering caused by plants?

7. What is one way in which animals cause rock weathering?

LESSON 1Key Concept Builder



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WeatheringKey Concept How do chemical processes change rocks?

Directions: Answer each question and explain its importance in the space provided.

Chemical Weathering Answer Why It Is Important

1. What does chemical weathering do?

2. In which type of environment is the rate of weathering the fastest?

3. How does the process of dissolving occur?

4. Which material dissolves most substances in chemical weathering?

5. What is the range of pH levels of acid?

6. What can make normal rain more acidic?

7. What combines during oxidation?

8. How does the pH of normal rain compare with the pH of vinegar?

9. What is the pH level of acid rain?



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Enrichment

In the 1930s, huge dust storms swept through the Great Plains in the Midwestern United States. Dust storms were a result of the mechanical weathering, or erosion, of once-fertile farmland that was caused mainly by wind. The Plains suffered from poor farming techniques and an eight-year drought. Farmers who had settled in the region used techniques that were not suited to the dry, treeless area and its soft soils. Overtilling and overgrazing, combined with the drought, exposed the fertile topsoil to the persistent winds.

Erosion and Pollution Erosion can also contribute to

pollution. Erosion caused by storm runoff can carry chemicals such as fertilizers, pesticides, and herbicides into surface water. Scientists have determined that natural wetlands filter much of the contamination resulting from agricultural runoff. Applying this knowledge to farming, farmers plant buffers next to waterways, using native plants rather than crops. The two main types—forest buffers and grass buffers—capture much of the sediment and chemicals that rainwater normally washes off farmland.

The roots of grass and forest buffers absorb nitrates and help control nitrate levels in the soil and groundwater. The

Buffering the Effects of Agriculture

Applying Critical-Thinking Skills Directions: Respond to each statement.

1. Compare wetlands, grass buffers, and forest buffers.

2. Predict where you think farm runoff would go if no buffers were in place. Analyze the effects that this runoff would have.

LESSON 1

buffers’ roots encourage the growth of bacteria in the soil. These bacteria eat nitrates and other chemicals deposited by fertilizers in the groundwater.

Reducing Runoff Grass waterways and grass hedges can be

used to prevent erosion in areas with heavy rainfall. By building grass-covered pathways at the lowest level of a field, farmers can divert runoff to these pathways. Because the waterways are covered with grass, topsoil from them does not wash away easily. Grass hedges go further, trapping sediment from runoff as water flows through them. Hedges slow the pace of runoff, reducing its physical effects on the land.

Farmers once cleared fields entirely to maximize crop area. Now many farmers preserve wide buffer zones on both sides of a waterway. Some streams that were turbid and oxygen-depleted because of runoff sediments, fertilizers, and pesticides are now healthy because buffer zones were restored.

Buffers provide more benefits than just controlling farm runoff. Forest buffers can be selectively harvested for timber or other forest products. Grass buffers can be harvested as feed for livestock. They can also be used to control erosion on construction sites and in urban recreation areas.

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Challenge

Ice WedgingWater becomes less dense and expands when it freezes. This decrease in density keeps

frozen water floating on top of a lake instead of sinking to the bottom, where it would damage wildlife and vegetation. Water can expand as much as 9 percent when it freezes.

Water flows into a crack, freezes, expands, and makes the crack a bit wider. More water then flows into the crack and expands the crack even more. Over time, the crack gets wide enough to cause stress on the rock, and the rock breaks. Over time, large rocks can become sand. The wedging action of ice is powerful and persistent in nature.

Rock-Smashing ExpansionDemonstrate ice wedging by observing the expansion of ice. Firmly plug one end of a

plastic drinking straw with a piece of clay. Completely fill the straw with water, and firmly plug the other end with another piece of clay. In the left-hand box below, draw your setup. Put the straw in the freezer overnight. The next day, carefully remove the straw from the freezer. In the right-hand box below, draw what you observe. Label your drawings.

Directions: Respond to each statement.

1. Describe what you observe about the frozen water in the straw. What happened to the clay plugs? What happened to the straw?

2. Relate your observations to the weathering process of ice wedging.

3. Decide whether ice wedging is mechanical or chemical weathering. Justify your decision.

LESSON 1



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What causes weathering? Over time, rocks that are exposed at Earth’s surface undergo mechanical and chemical weathering. You have already seen how mechanical processes break down a rock into small particles called sediment. Now you will model the mechanical weathering of rock and determine how much rock is weathered.

ModelSkill Practice LESSON 1: 30 minutes

Learn It Scientists use models in a lab for many reasons. One use of a model is to study processes that happen too slowly to study them efficiently outside of the lab. Weathering is such a process.

Try It 1. Read and complete a lab safety form.

2. Use the data table below to record your data.

3. Soak some rock chips in water. Then drain off the water and pat dry with paper towels. Use a balance to measure 10.0 g of the soaked rock chips.

4. Place the rock chips in a wide-mouthed plastic bottle. Add enough water to cover the chips. Put the lid on the bottle. Shake the bottle vigorously for 3 minutes. Use a timer to time the shaking.

5. Drain the water and carefully remove the rock chips. Pat off the water with a paper towel. Measure the mass of the damp rock chips to the nearest tenth of a gram. Record the results in the data table.

Data Table

Trial Mass of Rocks at End of Trial (g)

Amount of Mass Lost (g)

Percent of Mass Lost

Start 10.0 None None

1

2

3

4

5

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Skill Practice continued

6. Repeat steps 4 and 5 four additional times.

7. Calculate the percent of mass lost in each trial. Use the following steps. Record each answer in your data table.

a. Find the amount of mass lost. Subtract the mass at the end of the trial from the mass at the start of the trial.

b. Find the percent of mass lost. Divide the amount of mass lost (step a) by the mass at the start of the trial. Your answer should be to three decimal places. Then multiply by 100 to change the answer to a percent.

Apply It 8. How did this percentage change during the experiment?

9. Key Concept What type of weathering did you model in this experiment? How is this model similar to the natural process that it represents? How does it differ?

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LESSON 1Lesson Quiz A

Weathering True or False Directions: On the line before each statement, write T if the statement is true or F if the statement is false.

1. Mechanical weathering changes the size of a rock.

2. Chemical weathering changes the materials in a rock.

3. Ice wedging is a chemical weathering process.

4. A rock with a great deal of surface area weathers more easily.

5. Weathering prevents plants from getting water and substances it contains.

6. Acid rain causes less chemical weathering than normal rain.

7. Oxidation is a type of mechanical weathering.

8. Dissolving can be an example of chemical weathering.

9. Most types of weathering are slower in cold, dry places.

10. Rocks containing minerals with low hardness undergo mechanical weathering more easily.

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Lesson Quiz B

WeatheringShort Answer Directions: Respond to each statement on the lines provided.

1. Compare and contrast mechanical and chemical weathering.

2. Describe two types of mechanical weathering.

3. Describe two types of chemical weathering.

4. Relate how surface area affects weathering rates.

5. State examples of two factors that affect weathering rates.

6. Assess the way weathering helps plants.

7. Differentiate normal rain from acid rain. Describe the way each affects the weathering of rock.

LESSON 1



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Lesson 2 | Soil

Student Labs and Activities Page Appropriate For:

Launch Lab 28 all students

Content Vocabulary ELL 29 all students

Lesson Outline ELL 30 all students

MiniLab 32 all students

Content Practice A 33 AL AL AL

Content Practice B 34 AL OL BL

Language Arts Support 35 all students

School to Home 37 all students

Key Concept Builders 38 AL AL AL

Enrichment 42 all students

Challenge 43 AL AL BL

Lab A 46 AL AL AL

Lab B 49 AL OL BL

Lab C 52 AL AL BL

Chapter Key Concepts Builder 53 AL AL AL

Assessment

Lesson Quiz A 44 AL AL AL

Lesson Quiz B 45 AL OL BL

Chapter Test A 54 AL AL AL

Chapter Test B 57 AL OL AL

Chapter Test C 60 AL AL BL

Teacher Support

Answers (with Lesson Outlines) T4



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Launch Lab LESSON 2: 10 minutes

What is in your soil?Soils are different in different places. Suppose you look at the soil along a river bank. Is this soil like the soil in a field? Are either of these soils like the soil near your home? What is in the soil where you live?

Procedure 1. Read and complete a lab safety form.

2. Place about a cup of local soil in a jar that has a lid. Add a few drops of liquid detergent.

3. Add water to the jar until it is almost full. Firmly attach the lid.


Think About This 1. How many different layers did your sample form?

2. Key Concept From your observations, what do you think makes up each layer?

4. Shake for 1 minute and place it on your desk.

5. Observe the contents of the jar after 2 minutes and again after 5 minutes. Record your observations in the Data and Observations below.

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SoilDirections: Use the clues and the terms listed below to complete the puzzle. NOTE: There is no empty square in the puzzle between the words of two-word terms. Some words may not be used.

biota climate decomposition horizon organic matter

parent material pore sediment soil topography

Content Vocabulary LESSON 2

CluesAcross 1. the shape of the land

4. the broken-down remains of dead plants and animals

6. all the living things in an area

9. the process that produces organic matter

10. mixture of weathered rock, rock fragments, decayed organic matter, water, and air

Down 2. the starting material that weathers and

forms soil

3. a small space in the soil

5. the average weather of an area

7. rock material broken down or dissolved in water

8. a layer of soil

1 2

3

4 5

6

8

9

10

7



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Soil A. What is soil?

1. is a mixture of weathered rock, decayed organic matter, mineral fragments, water, and air.

2. About half the volume of soil is made of materials.

a. Soil also contains water, other liquids, and .

b. In the soil, water and gases fill small holes called .

c. can flow through soil because pores are present.

d. The movement of water through pores is called .

3. The solid part of soil once part of living organisms is .

a. Organic matter forms when once-living material undergoes

by organisms in the soil.

b. Organic matter helps hold water and in the soil.

4. The part of soils is made from materials, such as rock

fragments, that have never been alive.

B. Formation of Soil

1. There are five of soil formation.

2. The starting material of soil is called .

a. Parent material is made of the rock or that weathers and forms soil.

b. The particle size and type of parent material can determine the

of the soil that develops.

3. is the average weather of an area. Soil can form rapidly

in , wet climates.

4. is the shape and steepness of the landscape.

5. The is all the organisms that live in a region. Some

biota in the soil form passages for to move through.

6. As time passes, weathering is constantly acting on and

sediment. Soil formation is a(n) , but slow process.

Lesson Outline LESSON 2



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C. Horizons

1. are layers of soil formed from the product of

weathering.

2. There are horizons common to most soils.

a. The is the part of the soil you are most likely to see when you dig a shallow hole; it contains most of the organic matter in the soil.

b. The usually contains a great deal of clay particles.

c. The consists of parent material.

D. Soil Properties and Uses

1. The of a soil determine the best use of the soil.

2. Plants depend on the that come from organic matter and the weathering of rocks.

3. There are major soil types in the world.

4. Soil type depends partly on .



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How can you determine soil composition? Scientists can sometimes feel soil to help identify the soil’s composition. Can you identify soil by feel?

Procedure 1. Read and complete a lab safety form.

2. Carefully observe your soil sample with a magnifying lens. In the Data and Observations below, record the sizes of the particles you observe.

3. Fill a spray bottle or a sprinkling can with water. Use the water to moisten the soil.


Analyze and Conclude 1. Classify What texture does the soil have?

2. Key Concept What other properties of your soil sample did you observe?

MiniLab LESSON 2: 20 minutes

4. Rub some moist soil between your fingers.

5. Use Figure 5 in your textbook and your observations to classify your soil as mostly sand, mostly silt, or mostly clay.



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Content Practice A LESSON 2

SoilDirections: Complete this chart by choosing terms from the word bank and writing them in the correct spaces.

A-horizon B-horizon biota C-horizon climate

color consistency fertility infiltration parent material

pH soil moisture structure temperature texture

time topography

1. List nine terms that describe the properties of soils:

a.

b.

c.

d.

e.

f.

g.

h.

i.

2. List three terms that describe the layers where soils are found:

a.

b.

c.

3. List five terms that explain the formation of soils:

a.

b.

c.

d.

e.

Soils



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Content Practice B LESSON 2

Soil Directions: Answer each question on the lines provided. Use complete sentences.

1. How do soils sustain life?

2. What is the difference between inorganic and organic material?

3. What is the importance of parent material in soil formation?

4. What effect does climate have on parent material?

5. How do biota in soil accelerate the process of soil formation?

6. How does topography affect soil formation?

7. Why are soils considered to be young even though they are thousands of years old?

8. What makes up the A-horizon?



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Word-Building Activity: Sentence CompletionDirections: Before reading Weathering and Soil in your textbook, study the terms and definitions below. Then write the term that correctly completes each sentence.

chemical weathering n. process that changes the minerals that are part of a rock into new materials

decomposition n. process of changing once-living material into dark-colored organic matter

mechanical weathering n. process that breaks a rock into smaller pieces without changing its chemical makeup

oxidation n. oxygen combining with other elements or metals in rocks

soil n. mixture of weathered rock, rock fragments, decayed organic matter, water, and air

weathering n. destructive process that breaks down and changes rocks that are exposed at Earth’s surface

1. A common example of is when oxygen combines with iron and forms rust.

2. Rain causing a boulder to slide down a cliff and break apart on the ground is an

example of because the process does not change the makeup of the boulder.

3. Most of the organic material in comes from the natural decay of animal bodies, foliage, and plants.

4. After undergoing years of , the cement wall was breaking apart and needed to be repaired.

5. An example of is when organisms that live in the soil break down twigs and leaves for food.

6. One cause of is a weak acid that results from the combination of carbon dioxide and water in the air.

LESSON 2Language Arts Support

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LESSON 2Language Arts Support

Reading-Comprehension Activity: True or FalseDirections: On the line before each statement, write T if the statement is true or F if the statement is false. If a statement is false, correct the sentence by crossing out the incorrect term and writing the correct term above. Study the example before you begin.

Example: abrasion F Glaciers, wind, and waves along a lakeshore or ocean can cause ice wedging.

1. Mechanical weathering is the physical breakdown of rocks, and chemical

weathering changes the makeup of a rock.

2. Ice wedging is an example of chemical weathering.

3. An acid is a substance with a pH between 0 and 7.

4. Oxidation is an example of mechanical weathering.

5. The rate of weathering depends on climate and rock type.

6. Acid rain is a more powerful weathering agent than normal rain.

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School to Home LESSON 2

Soil Directions: Use your textbook to answer each question or respond to each statement.

1. Soil stores water, provides nutrients, and anchors the roots of plants.

Identify the main materials that make up soil.

2. The quality and composition of soil vary from place to place, depending on how the soil was formed.

Explain the five factors of soil formation.

3. As you dig into the soil, there are different soil horizons.

What are soil horizons? How do they form?

4. The properties of soil determine its best use.

Which soil properties can you observe? What can they tell you about soil?

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SoilKey Concept How is soil created?

Directions: Answer each question in the space provided.

3. What is climate?

4. What are two ways climate is measured?

•

•

5. In what type of climate is parent material quickly weathered?

CLIMATE

1. What is parent material?

2. What are two ways parent material form soil?

•

•

6. What does biota mean?

7. What effect do biota have on soil formation?

8. What are two specific ways biota assist soil formation?

•

•

9. What is topography?

10. How does a flat topography affect soil formation?

11. How does a steep topography affect soil formation?

12. What are three things that are true about soil formation?

•

•

•

13. What often happens to the level of organic material in soil over time?

14. What materials produce layers in the soil?

BIOTA

TOPO

GRAPH

Y

TIME



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SoilKey Concept What are soil horizons?

Directions: Label the diagram with these three terms on the lines provided: A-horizon, B-horizon, C-horizon.

1.


Directions: Answer each question in the space provided.

A-horizon

2. What is present there? 3. How does this horizon benefit plants?

B-horizon

4. What is present there? 5. How does the B-horizon form?

C-horizon

6. What part of rock formation makes up this layer?

7. Which types of parent material might be in this horizon?


Matthew Ward/Getty Images


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SoilKey Concept Which soil properties can be observed and measured?

Directions: On each line, write the term from the word bank that correctly answers each question about soil properties. Some terms may be used more than once or not at all.

color consistency fertility infiltration pH

soil moisture structure temperature texture

Which soil property …

1. indicates how much water is in soil pores?

2. is a measure of the ability of a soil to support plant growth?

3. describes how the particles are held together?

4. is based on how light or dark soil is?

5. describes how fast water enters soil?

6. identifies the types of rock pieces?

7. changes with daily cycles and weather?

8. indicates the acidity of soil?

9. is the hardness or softness of a soil?

10. describes a grainy quality to the soil?

11. can indicate a reading between 5.5 and 8.2?

12. can indicate a prism shape?

13. describes the amount of elements that are essential for plant nutrition?

14. is measured by drying samples at 100°C?

15. indicates a soft, slippery characteristic when it is moist?

16. describes differences in size?




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SoilKey Concept How are soils and soil conditions related to life?

Directions: Answer each question or respond to each statement in the space provided.

Soils

1. Give two reasons why soils are important.

•

•

2. List three parts of soil.

•

•

•

3. List two properties of soils that plants depend on.

•

•

Inorganic Parts Organic Parts

4. What is meant by the inorganic part of soils? 8. What is meant by the organic part of soils?

5. How are soil fragments classified? 9. What are three examples of organic matter in soils?

•

•

•

6. What does the size of the inorganic matter in soils affect?

10. How does organic matter form in soils?

•

•

7. What are three examples of inorganic matter?

•

•

•

11. What important properties does organic matter give to soils?

•

•

•

•




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Enrichment LESSON 2

Saving the SoilSoil contains important nutrients, such

as phosphorus, carbon, and nitrogen, that make it possible for crops and other plants to grow and thrive. Many factors, including the types of plants grown and the way farmers grow them, can change the composition of soil.

Poor Farming Techniques Some traditional methods of farming

can deplete soil of valuable nutrients or deposit harmful elements. For example, irrigation of crops causes excess salt deposits and pesticide residues to build up in soil. Runoff into natural waterways can carry pesticides and fertilizers that pollute the water. Poorly managed irrigation can lead to soil erosion. Most experts believe that often it is better to work with a soil’s natural dry state rather than try to change it through irrigation. Irrigation can rapidly deplete an area’s available groundwater.

Dryland Farming Dryland farming is an agricultural

technique for cultivating land that normally receives little rainfall. Dryland farming uses only small amounts of fertilizer, compared to irrigation farming.

In dryland farming, a farmer will leave part of the farmland unplanted for one growing season. The unplanted ground is called fallow. A crop-fallow rotation

Applying Critical-Thinking Skills Directions: Respond to each statement.

1. Dryland farming can be an environmental problem when nitrates are released into groundwater. Explain how dryland farming can be an environmental advantage.

2. Identify areas of the United States where experts might recommend dryland farming. Justify your answer.

conserves nutrients and water. The farmer might till into the ground the stubble left by the previous crop. The nitrogen in the crop stubble breaks down into nitrate, and the fallow ground regains some of the nutrients that were used to grow the previous year’s crop. Adding small amounts of fertilizer further increases the amount of nitrate available in the soil.

Drawbacks Dryland farming potentially raises

nitrate levels in groundwater. While land lies fallow, nitrate from the crop stubble can be carried to groundwater by rain or melting snow. High levels of nitrate in drinking water can cause serious health problems in humans.

Solutions Dryland farming can be improved

through conservation tillage. With this method, a farmer does not till the crop stubble while the land lies fallow, but seeds the next crop on top of the stubble. This method saves at least one tilling. The more the land is tilled, the looser and more porous the soil will be, and the more easily water will travel through it, carrying nutrients away from plant roots. Conservation tillage can increase crop yields, extend the growing season, and reduce runoff of nitrates by rainfall.



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Life in the SoilSoil is home to a wide variety of living things. Most soil organisms are microorganisms,

such as bacteria, fungi, and viruses. But larger organisms live in the soil as well, such as plant roots, ants, termites, worms, and burrowing insects, animals, and rodents. For example, earthworms make tunnels that provide aeration to the soil. They eat soil, digest the microorganisms in it, and leave behind their waste as castings that contribute nutrients to the soil. Other organisms convert nitrogen. Some decompose the remains of dead organisms, so even dead organisms contribute to soil health.

What’s in Your Soil?Examine a shovelful of soil in an area where you might like to plant. Use local resources

to determine how to classify your soil. List and describe any living things that you can see in the soil. Decide what kind of plants would grow best in your soil. Develop a plan that includes what, if anything, you need to add to your soil to grow the plants. Chart your plan and diagram your garden. Be sure to take into account how much rainfall your plants will get, how much runoff and erosion might occur, and how exposed your garden is to sunlight and wind, which will affect the amount of evaporation that occurs. Finally, write an explanation about why you chose particular plants.

Challenge LESSON 2



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SoilMatching Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is used only once.

Lesson Quiz A LESSON 2

1. describes the ability of a soil to support plant growth

2. describes how quickly water flows through a soil

3. describes the size of the particles in a soil

4. describes the hardness or softness of a soil

5. describes the acidity of a soil

A. consistency

B. fertility

C. infiltration

D. pH

E. texture

True or False Directions: On the line before each statement, write T if the statement is true or F if the statement is false.

6. Clay-rich soils allow more water to move through than sandy soils.

7. Soils form more quickly on a steep hillside than on flat ground.

8. Soils form most effectively in cold, dry climates.

9. The B-horizon usually contains the most clay.

10. Soils that form near the equator are thicker and more fertile than soils that form near the poles.



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Lesson Quiz B LESSON 2

SoilCompletion Directions: On each line, write the term that correctly completes each sentence.

1. A clay-rich soil has a slippery when it is wet.

2. A soil that is rich in organic matter has a higher than a soil that has a great deal of inorganic matter.

3. Soils in humid climates can have a lower than soils in drier climates.

4. A soil that has a sandy feels gritty when it is rubbed between your fingers.

5. A wet, sandy soil has a slower rate than a dry, sandy soil.

Short Answer Directions: Answer each question or respond to each statement on the lines provided.

6. Differentiate Which one has the greatest amount of pore space—a sandy soil, a silty soil, or a clay-rich soil? Explain.

7. Write an example of the way in which topography affects the formation of a soil.

8. Compare and contrast the three major soil horizons.

9. Assess how climate affects the formation of soil in wet, warm climates.



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Lab A 40 minutes

Soil Horizons and Soil FormationSoil, the complex mixture of weathered rock and partially decayed organic matter, covers most of Earth’s land surfaces. Soil is different in different locations because it forms from different rocks and in different climates and topography. As soil develops, it forms horizontal layers that have different properties. These layers vary in color and thickness. Together, they form a soil profile. How can you model a soil profile and relate it to how soil formed at that location?

QuestionHow is a soil profile in a certain location determined by the soil-forming factors there?

Materialsindex cards glue colored pencils silt

clay sand topsoil

Safety

Procedure 1. Look at the Florida soil profile in your textbook.

Discuss the types of rocks, the climate, and the land features of Minnesota, Colorado, and Florida. You can use reference materials to get this information.

Record some similarities and differences.

2. Examine the soil profile from each of the samples shown in your textbook.

Record some similarities and differences.

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Lab A continued

3. Draw the sample profiles and mark the A-, B-, and C-horizons that are present on each drawing.

Form a Hypothesis 4. Use what you know about soil formation and the sample profiles to state how each

soil horizon relates to factors of soil formation.

5. Choose one of the three soil profiles (Florida, Minnesota, or Colorado) shown in your textbook. Use the provided materials to model this profile.

Label the model with the state and the horizons you see.

6. Examine the information about parent material, climate, and topography for the state you chose. Make generalizations about how soil profiles are affected by soil-forming factors.

Remember to use scientific methods.

Ask a Question

Form a Hypothesis

Test your Hypothesis

Analyze and Conclude

Communicate Results

Make Observations

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Lab Tips • Review where silt, clay, sand, and topsoil appear in soil horizons before modeling a soil

profile.

Analyze and Conclude 7. Were any of the profiles missing an A- , B-, or C-horizon?

Explain why a horizon might not be present in a profile.

8. Was one of the horizons thicker in any of the profiles?

What could explain this?

9. The Big Idea What did your conclusions show about how a soil profile relates to soil-forming factors?

Communicate Your ResultsAs a class, place a soil-profile model for each listed state on a map of the United States. For each profile, discuss what other states might have a similar soil profile.

Lab A continued



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Lab B 40 minutes

Soil Horizons and Soil FormationSoil, the complex mixture of weathered rock and partially decayed organic matter, covers most of Earth’s land surfaces. Soil is different in different locations because it forms from different rocks and in different climates and topography. As soil develops, it forms horizontal layers that have different properties. These layers vary in color and thickness. Together, they form a soil profile. How can you model a soil profile and relate it to how soil formed at that location?

QuestionHow is a soil profile in a certain location determined by the soil-forming factors there?

Materialsindex cards glue colored pencils silt

clay sand topsoil

Safety

Procedure 1. Look at the Florida soil profile in your textbook. Discuss the types of rocks, the climate,

and the topography of Minnesota, Colorado, and Florida. You can use reference materials to obtain this information. Record some similarities and differences.

2. Examine the soil profile from each of the samples shown in your textbook. Record some similarities and differences.



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3. Draw the sample profiles and mark the A-, B-, and C-horizons that are present on each drawing.

Form a Hypothesis 4. Use what you know about soil formation and the

sample profiles to state how each soil horizon relates to factors of soil formation.

5. Choose one of the three soil profiles (Florida, Minnesota, or Colorado) shown in your textbook. Use the provided materials to model this profile. Label the model with the state and the horizons you see.

6. Examine the information about parent material, climate, and topography for the state you chose. Make generalizations about how soil profiles are affected by soil-forming factors.

Lab B continued

Remember to use scientific methods.

Ask a Question

Form a Hypothesis

Test your Hypothesis

Analyze and Conclude

Communicate Results

Make Observations



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Lab Tips • Review where silt, clay, sand, and topsoil appear in soil horizons before modeling a soil

profile.

Analyze and Conclude 7. Were any of the profiles missing an A-, B-, or C-horizon?

Explain why a horizon might not be present in a profile.

8. Was one of the horizons thicker in any of the profiles?

What could explain this?

9. The Big Idea What did your conclusions show about how a soil profile relates to soil-forming factors?

Communicate Your ResultsAs a class, place a soil-profile model for each listed state on a map of the United States. For each profile, discuss what other states might have a similar soil profile.

Lab B continued

Extension

Choose a location on another continent. Find out whether the soil profile and soil-forming factors there support your hypothesis.



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Lab C

Porosity and PermeabilityDirections: Use the information and data from Lab Soil Horizons and Soil Formation to perform this lab.

You have learned that a soil profile is made of different types of soil. Different soils might be made of different materials and have different grain sizes. The size of the grains of a soil also affects size of the holes and spaces in the soil. These small holes and spaces in soil are called pores. Water flows around soil particles and through the pores. The volume of the pores in the soil is called porosity. The measure of how easily water flows through soil is called permeability. Permeability is related to porosity. In this investigation, you will design an experiment to measure the porosity and permeability of soil samples, and then you will determine how porosity and permeability are related.

Please note that you must complete Lab B before beginning Lab C. Also, have your teacher approve your design and safety procedures before beginning your experiment.



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Weathering and Soil End-of-Chapter Practice Directions: Work with a small group to design a demonstration showing the relationship between weathering and soil formation. Here is what you need to do to complete this activity:

• As a group, brainstorm ideas of how the relationship between weathering and soil formation can be demonstrated. Make a list of the ideas generated by the group.

Ideas to consider:

• Then,

Decide which idea will be the most interesting and possible to do:

List the steps needed to create the demonstration:

Make a list of the materials you will need:

Decide which role each member will play in completing the task.

• Prepare your demonstration.

Share you demonstration with your class. In some way, your demonstration should recognize that

• soil formation takes a very long time;

• weathering of rock occurs by mechanical and chemical processes;

• soils are measured by several different properties.

• Be prepared to answer questions from your teacher or classmates about the relationship between weathering and soil formation.

Chapter Key Concepts Builder

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Chapter Test A

Weathering and SoilMultiple ChoiceDirections: On the line before each question or statement, write the letter of the correct answer.

1. Mechanical weathering is any process that A. does not form a soil horizon. B. breaks rocks into smaller pieces. C. changes minerals into new ones.

2. Chemical weathering changes the A. size of a rock. B. materials in rock. C. the horizons of a rock.

3. Which is a type of mechanical weathering? A. abrasion B. infiltration C. consistency

4. Which process occurs in chemical weathering? A. abrasion B. dissolving C. ice wedging

5. Which material is an organic part of soil? A. clay B. water C. leaves

6. Which is NOT a factor in the formation of soil? A. biota B. climate C. fertility

7. Parent material in soil is in the A. A-horizon. B. B-horizon. C. C-horizon.

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Matching Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is used only once.

Chapter Test A continued

8. the size of grains of soil

9. a soil’s ability to support plants

10. how fast water enters soil

11. the amount of water in a soil

12. the hardness of soil

13. a soil’s acidity

A. consistency

B. fertility

C. infiltration

D. moisture

E. pH

F. texture

14. Label the A-, B-, and C-horizons of soil.

15. Which horizon contains the most organic matter? Write an O next to its label.

16. Write a P next to the parent material that weathered and formed this soil.

Interpreting a Diagram Directions: Use the diagram to respond to each statement.


Matthew Ward/Getty Images


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Short AnswerDirections: Respond to each statement on the lines provided.

17. Describe how plants and animals cause weathering.

18. Identify the areas of Earth where weathering occurs slowly and the areas where it occurs quickly.

19. Arrange these soil particles from largest to smallest—silt, clay, and sand. Identify the type of soil that water flows through most easily and explain why.

20. Explain two factors of soil formation.

Concept ApplicationDirections: Answer the question on the lines provided. Use complete sentences.

21. Infer Your family visits a large city where many buildings are made of rock. You observe that some of the addresses carved into the rock of the buildings are worn and hard to read. What can you infer about the rock?

Chapter Test A continued



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Chapter Test B

Weathering and Soil Multiple Choice Directions: On the line before each question or statement, write the letter of the correct answer.

1. Chemical weathering A. changes the size of rocks and minerals. B. is more likely to occur in a forest than a desert. C. is often caused by plant roots growing into cracks. D. occurs faster on larger rocks than on smaller rocks.

2. Which is true? A. All weathering occurs faster near the poles. B. Ice wedging is a minor process of weathering. C. Steep slopes slow down the weathering process. D. Normal water causes the most mechanical weathering.

MatchingDirections: On the line before each definition, write the letter of the term that matches it correctly. Not all terms are used.

3. processes that break rocks into smaller pieces

4. soil layer with the most organic material

5. processes that change a rock’s composition

6. soil components that were once alive

7. soil layer with the most parent material

8. this soil property determines the infiltration rate

9. depends primarily on the composition of the A-horizon

10. varies with the amount of moisture in a soil

11. would be slower in clay-rich soil than in sandy soil

A. A-horizon

B. B-horizon

C. C-horizon

D. chemical weathering

E. consistence

F. fertility

G. infiltration

H. mechanical weathering

I. organic matter

J. temperature

K. texture



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Interpreting a Diagram Directions: Use the diagram to respond to each statement.

12. On the diagram, label the soil horizon that is least developed with an L.

13. On the diagram, label the soil horizon that is most developed with an M.

14. Describe and label the soil’s B-horizon.

15. Deduce which soil horizon is most like the material the soil formed from and explain why.

Short AnswerDirections: Respond to each statement on the lines provided.

16. Compare and contrast the organic and inorganic components of a soil.

Chapter Test B continued



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17. Assess how mechanical weathering affects the rate of chemical weathering.

18. Write an example of the effect of climate on chemical weathering.

Concept ApplicationDirections: Respond to each statement on the lines provided. Use complete sentences.

19. Determine one example of mechanical weathering and one example of chemical weathering that you might observe near your school.

20. Analyze the color, texture, and infiltration rate of a soil that is rich in organic matter and contains a large volume of clay.

21. Select four properties of soil that a farmer would value when choosing land to grow crops on.

Chapter Test B continued



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Chapter Test C

Weathering and Soil Multiple Choice Directions: On the line before each question or statement, write the letter of the correct answer.

1. Mechanical weathering by plants is most effective A. in a desert. B. in a forest. C. in a stream. D. on a mountaintop.

2. Abrasion would be most effective on a rock A. covered with ice. B. with a small surface area. C. in a swiftly flowing stream. D. when temperatures are low.

3. Which models chemical weathering? A. exposing a rock to rain B. freezing a rock in a container of water C. breaking rock into pieces with a hammer D. shaking a container of sand with a rock in it

4. Inorganic components of most soils include A. clay, sand, and bacteria. B. air, water, and minerals. C. partially composed matter. D. parent material and animal waste.

5. In which location would soil form the fastest? A. a plain near the poles B. a forest in a warm climate C. a cold mountainous region D. a gentle slope in a dry climate

Completion Directions: On each line, write the term that correctly completes each sentence.

6. Chemical weathering changes the of rock.

7. A soil that is wet will have a slower rate than a soil that is dry.

8. Rock that undergoes combines with oxygen from the air.

9. is a soil property that changes daily with weather and most affects the upper A-horizon.



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10. The of a dry soil that is rich in clay is similar to flour.

11. A farmer would test the of a soil to find out how hard it is.

12. The large particles in sand do not hold together well, giving it a

grainy .

13. The amount of nutrients in soil determines its .

Interpreting a DiagramDirections: Respond to each statement in the space or the lines provided.

14. Illustrate and label a typical soil profile that includes three horizons. Include some internal detail in each horizon.

15. Differentiate the horizons in your diagram by describing each one in detail.

Chapter Test C continued



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Short Answer Directions: Respond to each statement on the lines provided.

16. Contrast places where mechanical weathering is most effective with places where chemical weathering is most effective.

17. Assess the importance of organic matter in soil.

18. State why most B-horizons are rich in clay.

Concept Application Directions: Respond to each statement on the lines provided. Use complete sentences.

19. Determine which soil type is more fertile—a soil rich in clay or a soil rich in sand? Explain your choice.

20. Specify the conditions that work against the formation of deep, rich soils in mountain areas.

21. Evaluate whether mechanical or chemical weathering is more important in forming desert soil. Explain your answer.

Chapter Test C continued


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Teacher Pages

Weathering and Soil T1

Lesson Outlines for Teaching T2

Answers T6

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T2 Weathering and Soil

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Lesson Outline for Teaching Lesson 1: WeatheringA. Weathering and Its Effects

1. The chemical and physical processes that change objects on Earth’s surface over time are called weathering.

2. Over thousands of years, mechanical weathering breaks up rocks into smaller pieces.

B. Mechanical Weathering

1. During mechanical weathering, physical processes break rocks into smaller pieces.

2. Mechanical weathering does not change the chemical makeup of the rock.

3. When mechanical weathering breaks a large rock into smaller pieces, the total surface area of the rock increases.

4. Between sandy and clay soils, clay soil holds more water and nutrients because it consists of smaller particles that have more surface area.

5. In ice wedging, water enters cracks in rocks and freezes. Water expands when it freezes and makes the cracks larger.

6. Grinding rock away by friction or impact is called abrasion.

7. Plants growing in a crack in a rock and animals burrowing through loose rock can cause mechanical weathering.

C. Chemical Weathering

1. During chemical weathering, the materials that make up rocks are changed into new materials.

2. Water is an important agent of chemical weathering because most substances dissolve in water.

3. A(n) acid is a more powerful weathering agent than water.

a. The measure of acidity is called pH.

b. An acid has a pH less than 7.

c. Rain weathers rock because rain is slightly acidic.

d. Acid rain contains pollutants that make its pH less than 5.

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4. Oxygen combines with other elements or molecules during oxidation.

a. Most oxygen used in oxidation comes from the air.

b. The product of oxidation is a(n) oxide.

c. Oxides are useful because they form ores, which people use to obtain metals.

d. The outer part of a rock oxidizes the most because it has more contact with oxygen in the air.

D. What affects weathering rates?

1. Mechanical and chemical weathering depend on water and temperature.

a. Mechanical weathering occurs fastest in areas that have a lot of temperature changes.

b. Chemical weathering is fastest where the climate is warm and wet.

c. Overall, weathering occurs fastest in regions near the equator.

2. The type of rock also affects how fast weathering occurs. The most easily weathered mineral in a rock determines how quickly the rock weathers.

Discussion QuestionHow does the climate where you live affect the speed of weathering?

Answers should indicate that rocks weather fastest in warm, wet climates and that weathering is slower in cold, dry places.


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Lesson Outline for Teaching Lesson 2: Soil A. What is soil?

1. Soil is a mixture of weathered rock, decayed organic matter, mineral fragments, water, and air.

2. About half the volume of soil is made of solid materials.

a. Soil also contains water, other liquids, and gases.

b. In the soil, water and gases fill small holes called pores.

c. Water can flow through soil because pores are present.

d. The movement of water through pores is called porosity.

3. The solid part of soil once part of living organisms is organic matter.

a. Organic matter forms when once-living material undergoes decomposition by organisms in the soil.

b. Organic matter helps hold water and nutrients in the soil.

4. The inorganic part of soils is made from materials that have never been alive.

B. Formation of Soil

1. There are five factors of soil formation.

2. The starting material of soil is called parent material.

a. Parent material is made of the rock or sediment that weathers and forms soil.

b. The particle size and type of parent material can determine the properties of the soil that develops.

3. Climate is the average weather of an area. Soil can form rapidly in warm, wet climates.

4. Topography is the shape and steepness of the landscape.

5. The biota is all the organisms that live in a region. Some biota in the soil form passages for water to move through.

6. As time passes, weathering is constantly acting on rock and sediment. This means soil formation is a(n) constant, but slow process.

C. Horizons

1. Horizons are layers of soil formed from the movement of the products of weathering.

2. There are three horizons common to most soils.

a. The A-horizon is the part of the soil you are most likely to see when you dig a shallow hole; it contains most of the organic matter in the soil.

b. The B-horizon usually contains a great deal of clay particles.

c. The C-horizon consists of parent material.



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D. Soil Properties and Uses

1. The properties of a soil determine the best use of the soil.

2. Plants depend on the nutrients that come from organic matter and the weathering of rocks.

3. There are 12 major soil types in the world.

4. Soil type depends partly on climate.

Discussion QuestionSuppose you have three soil samples. One sample of soil is red, is slippery when wet, and holds water well. Another sample is a light-yellow tan and contains sharp pieces of rock. A third sample is dark and contains small pieces of twigs and leaves. Which horizon is the source of each sample?

The first sample contains a great deal of clay and is probably from a B-horizon. The second sample contains parent material, so it probably is from a C-horizon. The organic matter and dark color of the third sample shows that it is from an A-horizon.




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What do you think? (page 1) 1. Disagree; erosion is the transport of weathered

material.

2. Disagree; natural processes are the main cause of weathering.

3. Agree; as plants grow in cracks of rocks, their roots expand in length and depth, causing the cracks to widen.

4. Agree; air and water exist within the pore spaces of soil.

5. Agree; mature soil can take many thousands of years to form.

6. Disagree; soil varies from location to location.

Lesson 1Launch Lab (page 8) 1. Student answers should reflect that the rocks

are alike in that they are still rocks. They differ in that they are smoother, smaller, and more broken the more they are shaken.

2. Possible answer: The rocks hit against each other and against the jar and lid, breaking off small pieces and making them rounder.

Content Vocabulary (page 9) 1. oxidation

2. Mechanical weathering

3. environment

4. chemical weathering

5. weathering

MiniLab (page 12) 1. The hydrochloric acid reacted with the rock.

Bubbles on the rock indicated that a chemical reaction occurred.

2. The rocks would undergo chemical weathering.

Content Practice A (page 13) 1. (in any order) Rock and water grind other rock.

Animals burrow into soil. Intense temperature causes rocks to expand. Ice expands cracks in rock. Plants cause rocks to crumble.

2. (in either order) Pollutants dissolve in water. Molecules combine and form oxides.

Content Practice B (page 14) 1–5. (in any order) Abrasion causes weathering

because a rock will break when water grinds against it. Ice wedging causes weathering because water freezes and expands cracks in rock. Intense temperatures cause weathering because rocks expand and crack. Plants cause weathering because stems and roots press against a rock’s cracks and break it. Animals cause weathering because they burrow into soil, causing rocks to break.

6. Oxidation is the process that combines oxygen with other elements or molecules.

7. Normal rain has a pH of about 5.6 and can cause chemical weathering

8. Acid rain has a pH of 4.5 or less and causes more chemical weathering than normal rain causes.

9. Weathering is the mechanical and chemical processes that change objects on Earth’s surface over time.

10. Mechanical weathering breaks rocks into smaller pieces.

11. Chemical weathering changes the minerals, which are part of a rock, into new materials.

Math Skills (page 15) 1. 242 cm2

2. 384 cm2

3. 186 cm2

4. 450 cm2

School to Home (page 16) 1. Answers will vary but should demonstrate

an understanding of common processes that constitute mechanical weathering. Students might observe cracks forming in a sidewalk as a result of a growing tree root, a rock that has fallen and smashed into pieces, ice wedging, or any type of rock that is cracked because of the work of natural elements.

2. Answers will vary but should demonstrate an understanding of common processes that constitute chemical weathering. Students might observe oxidation or rust of outdoor materials or the wearing away of a building’s façade due to acid rain or other pollutants in the air.

Key Concept Builder (page 17) 1. ice wedging

2. abrasion

3. surface area

4. oxide

5. burrowing

6. pH


8. acid

9. crumbling

10. acid rain

Key Concept Builder (page 18) 1. Drawing should depict the cracking of the

rock as ice forms.

2. Ice wedging occurs when water enters cracks in rocks, freezes, and expands as the water turns

Answers

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to ice, which causes the rock to break apart.

3. Drawing should depict some type of rock abrasion, such as rock grinding against rock, glaciers, wind, or wave action.

4. Abrasion is the grinding away of rock by friction or impact. For example, waves or wind can cause rock to break apart.

5. Drawing should depict a plant growing in a crack in a rock, showing the crack expanding and/or rock breaking.

6. Plants can cause weathering when they grow into cracks in rocks. As the stem and roots get larger, they push against the rock and eventually break it apart.

7. Drawing should depict an animal burrowing into the soil or a hole made by an animal.

8. Animals can cause weathering when they burrow into soil. Water enters the hole, causing weathering, or the animal loosens rock by its burrowing activity.

Key Concept Builder (page 19) 1. breaks rocks into smaller pieces; possible

answer: because it creates soil

2. thousands of years; possible answer: because of the importance of using soil correctly

3. surface area increases; because it increases mechanical weathering of the rock

4. water enters crack in rocks, water freezes and expands, crack widens, and rock breaks apart; possible answer: because it breaks apart rock in cold climates

5. winds carry grains of sand, this sand rubs against rock, the rock breaks apart; possible answer: because wind weathers rock in dry climates

6. plant grows inside a crack in a rock, plant gets larger and presses against the rock, rock breaks apart; possible answer: because trees that germinate in cracks break the rock apart

7. create holes in ground where water can enter; possible answer: because animals help build soil

Key Concept Builder (page 20) 1. changes the minerals, which are part of a

rock, into new materials; possible answer: because it helps create soil

2. in warm, wet places; possible answer: because soil formation could occur more quickly

3. when minerals break into smaller parts in solution; possible answer: because it causes normal rain to become more acidic

4. water; possible answer: because wet, warm places have more rapid chemical weathering

5. 0–7; possible answer: because the more acidic a solution is (the lower it is on the pH scale),

the faster it can chemically weather rock

6. acid-forming chemicals that enter the air from natural sources; pollutants

7. oxygen with other elements or molecules; possible answer: because oxidation can cause chemical weathering

8. Normal rain is slightly acidic with a pH of around 5.6; vinegar is more acidic with a pH of 2 to 3; possible answer: Vinegar and normal rain can cause chemical weathering.

9. a pH of 4.5 or less; possible answer: because acid rain causes more chemical changes than normal rain

Enrichment (page 21) 1. Wetlands, grass buffers, and forest buffers filter

sediment and chemicals from runoff. Wetlands and some forest buffers occur naturally, but other forest buffers and grass pathways and hedges are planted. Grass buffers and a part of planted forest buffers can be harvested.

2. Possible answer: Some runoff ends up in groundwater, which might enter the drinking water supply and water supply used for crop irrigation. High levels of some chemicals in drinking or irrigation water can be harmful to humans or livestock that drink this water and eat these crops. Other runoff ends up in surface water—streams, rivers, lakes, and the ocean. Chemicals in this water can affect fish and other organisms in the water ecosystems.

Challenge (page 22) 1. Possible answers: The water expanded, pushing

the plugs out of the straw. Or the straw might be split and expanded in the middle.

2. Possible answer: Water expands as it freezes. It exerts force on whatever contains it. Like the plugs of clay, the sides of a rock get pushed apart.

3. Ice wedging is mechanical weathering because no new substances are formed.

Skill Practice (page 23) 8. Students should see a change in mass of about

1 percent in each trial. Actual results will vary with the hardness of the rock. Softer rocks might show larger percentages than harder rocks. Careful drying will reduce errors in results.

9. Mechanical weathering is modeled and is similar to natural mechanical weathering because no chemical change takes place and the rock is broken into smaller pieces. The model takes place much more quickly.

Lesson Quiz A (page 25)True or False 1. T

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2. T

3. F

4. T

5. F

6. F

7. F

8. T

9. T

10. T

Lesson Quiz B (page 26)Short Answer 1. Both are processes that change rock.

Mechanical weathering breaks rocks into smaller pieces; chemical weathering changes the chemical composition of rocks.

2. Student responses should address two of the following: ice wedging, abrasion, plants. Possible answers: Ice wedging occurs when water freezes and expands inside cracks in rock. This breaks the rock into smaller pieces. Abrasion is the grinding away of rock by friction or impact. Plant roots grow inside and widen cracks in rock. Animals create holes in soil that allow water to penetrate and weather rock. Animals also dig through loose rock, helping to break it down.

3. Possible answers: Dissolving occurs when minerals in rock break up into smaller parts in solution. Normal rain and acid rain are acidic, and they weather rock. Oxidation combines the element oxygen with other elements or molecules. Most of the oxygen needed for oxidation comes from the air.

4. Surface area of an object is all the space on its surface plane. The rate of weathering depends on the surface area of a rock that is exposed. Increased surface area allows a greater effect on soil with smaller particles. It also increases the rate of chemical weathering.

5. Possible answers: Environment and rock type are two factors that affect weathering rates. Mechanical weathering occurs faster in places where temperatures change frequently. Chemical weathering occurs fastest in places that are warm and wet. Rock type is important because rocks containing minerals with low hardness undergo mechanical weathering more easily.

6. Water pools on the surface of rocks and attaches to grains of soil. A greater surface area means more water, along with any substances the water contains, sticks to surfaces. Soils that can hold higher concentrations of moisture and nutrients are better for plant growth.

7. Acid rain is more acidic than normal rain, which is slightly acidic. Both cause chemical weathering of rock. However, because of acid rain’s greater acidity, it can cause great damage to structures made of rock.

Lesson 2Launch Lab (page 28) 1. Answers will vary depending on soil type.

Most soils will produce a bottom layer of the heaviest material including gravel, sand, and some organic material. A second layer will form within an hour composed mainly of silt, clay, and organic matter. The water above the soil will be cloudy. With time, the clay particles will settle as a third layer on top. The water above the soil layers will appear clear.

2. Answers will vary, but students should recognize size differences in the particles in each layer.

Content Vocabulary (page 29) 1. topography

2. parent material

3. pore

4. organic matter

5. climate 6. biota

7. sediment

8. horizon

9. decomposition

10. soil

MiniLab (page 32) 1. Answers will vary. Possible answers include

gritty (sand), sticky (clay), and smooth (silt).

2. Possible answer: particle size, color, presence of organic material, ability to absorb water

Content Practice A (page 33) 1. (in any order) color, texture, structure,

consistency, infiltration, soil moisture, pH, fertility, temperature

2. A-horizon, B-horizon, C-horizon

3. (in any order) parent material, climate, biota, topography, time

Content Practice B (page 34) 1. Soils hold water and provide valuable

nutrients for plants. They also anchor plants so they can grow toward the Sun.

2. Inorganic material has never been alive, and organic matter is the remains of something that was once alive.

3. Parent material is the starting material of soil.


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It consists of rock or sediment that weathers and forms soil.

4. A warm, wet climate accelerates weathering of parent material.

5. Biota form passages that allow water to move through the soil and assist with decomposition.

6. Land that is flat allows water to enter the soil, but water washes away soil on steep topography.

7. Although soils are constantly changing, the process is very slow.

8. Organic matter made from the decay of roots and the action of soil organisms make up the A-horizon.

Language Arts Support (page 35) 1. oxidation

2. mechanical weathering

3. soil

4. weathering

5. decomposition


Language Arts Support (page 36) 1. T

2. F; Students should cross out chemical and write mechanical.

3. T

4. F; Students should cross out mechanical and write chemical.

5. T

6. T

School to Home (page 37) 1. Soil is a mixture of weathered matter from

rock, rock fragments, and decayed organic materials that were once part of living organisms, water, and air.

2. Five factors affect soil formation. Parent material determines the minerals that make up soil. Climate affects the rate of weathering. For example, a climate that is warm and wet speeds chemical weathering. Some biota that live in soil include decomposers that add organic matter to soil. Topography is a factor—steep slopes can slow soil formation, while flat areas can speed it up. Time determines the amount of weathering that occurs to form soil.

3. Horizons are the different layers of soil. They form from the weathering of parent rock and the movement of the products of weathering.

4. Possible answer: The texture of soil can be observed by looking at the size of its particles.

Observing the soil’s horizons can give information about its best use. For example, a soil that is deep and has few horizons is good for farming. The color of soil shows the amount of organic matter it contains. A dark soil with a great deal of organic matter holds nutrients and water well and is good for farming and gardening.

Key Concept Builder (page 38) 1. the starting material of soil

2. weathering of rock in the same place where the rock formed; pieces of rock that are carried by wind or water to another place

3. the average weather of an area

4. amount of precipitation, average annual temperatures

5. warm, wet climates

6. all organisms living in a region

7. speed up soil formation

8. form passages for water, decomposition

9. the shape and steepness of the landscape

10. It speeds weathering.

11. Water running downhill carries soil away.

12. occur over time, change constantly, change slowly

13. It increases.

14. materials that are in different states of soil formation

Key Concept Builder (page 39) 1. Students should correctly label the soil diagram

with the A-horizon for the top section, the B-horizon for the center section, and the C-horizon for the bottom, parent-material section.

2. darker soil that contains organic matter from the decomposition of living things

3. provides nutrients for plant growth

4. clay and other materials

5. Water carries clay particles though pores and deposits them below the A-horizon.

6. parent material

7. rock, transported material

Key Concept Builder (page 40) 1. soil moisture

2. fertility

3. structure

4. color

5. infiltration

6. texture

7. temperature


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8. pH

9. consistency

10. structure

11. pH

12. structure

13. fertility

14. soil moisture

15. consistency

16. texture

Key Concept Builder (page 41) 1. Possible answer: Soils help plants survive by

storing water for them, providing nutrients, and anchoring them so they can grow toward the Sun. We get food from animals, which eat plants that have grown in the soil.

2. any three of the following: weathered rock, rock fragments, decayed organic matter, water, air

3. Dark soil absorbs sunlight. Organic matter holds water and provides plant nutrients.

4. the materials that have never been alive

5. by their size

6. the properties of the soil

7. sand, silt, clay

8. the remains of something that was once alive

9. leaves, dead insects, waste products

10. leaves fall from trees, living things die

11. gives it a dark color that absorbs sunlight, helps it hold water, helps it hold plant nutrients, holds minerals together in clusters

Enrichment (page 42) 1. Dryland farming allows farming in dry areas,

uses less fertilizer, and conserves groundwater.

2. Possible answer: In the United States, areas might include the Midwest, the northern and southern Plains, and the corn belt. The soils are naturally dry and retain nutrients better without irrigation.

Challenge (page 43)Student answers and plans will depend on the soil they examine. Local resources should help them decide which type of soil they have. Help them find a soil-texture diagram that determines soil type—loamy sand, clay loam, silty loam—according to the proportions of sand, silt, and clay. Students might see some living and dead organisms. They can estimate the amount of organic matter in the soil roughly; a rule of thumb is that the darker the soil is, the more organic matter (or compost) the soil contains. Students also need to know the amount of rainfall the plants they have chosen need and how much generally falls. Their garden diagrams

should include a plan for avoiding erosion and for soil conservation.

Lesson Quiz A (page 44)Matching 1. B

2. C

3. E

4. A

5. D

True or False 6. F

7. F

8. F

9. T

10. T

Lesson Quiz B (page 45)Completion 1. consistency

2. fertility

3. pH

4. texture

5. infiltration

Short Answer 6. A sandy soil has the greatest amount of pore

space because sand particles are much larger than silt or clay particles. Being larger, they are not as tightly packed, leaving bigger spaces between the grains.

7. Possible answer: Soil would develop more quickly on a flat area of land than on a hillside. Water would wash the soil from the slope.

8. The A-horizon is the best developed. It contains the most organic matter. The B-horizon contains clay and other inorganic materials washed down from the A-horizon. The C-horizon is the least developed horizon and often contains large pieces of parent material.

9. Weathering occurs more easily and more quickly in wet, warm places. As a result, soils are thicker and better developed in these areas than in drier, colder ones.

Labs A and B (pages 46, 49) 4. A possible general hypothesis might be: If you

know information about parent material, climate, and topography for a particular soil profile, then you can make generalizations about that profile because soil profiles are affected by soil-forming factors.

5. In this step, students should pick one state profile to model and test their hypothesis. Students should use an index card, glue, and


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the silt, clay, sand, and topsoil to make their model. Students should start at the bottom with the C horizon and spread a thin layer of glue on the card wide enough to represent the C horizon of the state they chose. They should then carefully sprinkle on the materials that best represent that horizon, making sure all the glue is covered. Excess materials can be lightly shaken off. Students will repeat these steps for the remaining horizons. Be sure to remind students to leave room for labels. The state name and horizons should be labeled, and attention should be paid to the scale or size of each horizon as it relates to the other horizons in the profile.

6. Before students make their generalizations, remind them that the soil-forming factors include: parent material, climate, topography, biota, and time. Students’ generalizations should mention all of these factors as they pertain to their selected soil profile.

7. All three profiles contained an A, B, and C horizon. Sometimes a horizon may not be present in a profile for a variety of reasons. For example, young soils may not be old enough to have developed a B or C horizon and will be thin. Climate conditions such as drought may cause horizon development to be slow. Erosion may cause the topmost layers to be removed periodically resulting in a missing A horizon. In addition, a lack of organic material may cause A horizons to be thin and not easily noticed.

8. Extreme conditions create extreme differences in horizon size. Older soils will have well-developed horizons. Soils with large amounts of organic material will have thick A horizons (Minnesota). Sandy soils may have lots of leaching and thick B horizons (Florida). Young soils may have thicker C horizons with much broken-up parent material (Colorado).

9. Horizons with different thicknesses should illustrate the factors involved in soil formation. Extremes in any factor will cause extremes in horizon formation. For example, plenty of organic matter creates a thick A horizon. Wet climates create leaching, which in turn creates thick or clay-filled B horizons. Wet climates can also cause rapid weathering of parent material, which is exhibited in thick C horizons. Similarly, climates with varying temperature extremes can create large C horizons.

Communicate Your Results Students should place a soil-profile model on Minnesota, Colorado, and Florida. Students should identify states with similar soil profiles based on similarities in the rock type, the climate, and the topography of those areas. For

example, Wisconsin soil profiles might be similar to those in Minnesota, Wyoming soil profiles might be similar to those in Colorado, and Alabama soil profiles might be similar to those in Florida. Students should understand that each state will have a wide variation of soil profiles and that this comparison is general.

B. Extension The soil profile and soil-forming factors in a location on another continent should support students’ hypotheses. The same five factors of soil formation and influences of rock type, climate, and topography will apply to any location.

Lab C (page 52)Please note:

• Students must complete Lab B before they are assigned Lab C.

• The procedure given below is just one possibility of many.

• If you have students perform the labs they design, make sure proper safety precautions are included before allowing them to proceed.

Sample procedure:

Ask a question What is the relationship between porosity and permeability of soil?

Form a Hypothesis Student hypotheses will vary, but the following is an example: If a soil sample has a high porosity, then it will have a high permeability because water will move easily through the pore spaces.

Test Your Hypothesis Testing procedures will vary, but the following is an example:

To determine porosity:

• Pour 100 ml of water into your cup and draw a line at the water level. Pour the 100 ml of water back into a graduated cylinder.

• Fill the same cup with the first soil sample to this fill line. Carefully pour the water from the graduated cylinder into the cup until the water reaches the top of your sample. Record the volume of water remaining in the graduated cylinder.

• Subtract the volume of water remaining in the graduated cylinder from the original volume of water in the cup (100 ml). Record the result. The volume of water you added to the soil sample is the pore space.

• To determine the porosity of the sample (a percent value), divide the pore space volume by the total volume and multiply the result by 100. Record the porosity of the sample.

To determine permeability:

• Hold an empty cup with a hole in it over an empty container.

• Carefully pour your sample into the cup with the hole, allowing the water to drain into the jar.


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Answers continued • Use the stopwatch to measure how long it takes

to pour 100 ml of water into the sample until it drains out of the sample. Record the result.

• Repeat steps with the remaining samples.

Analyze and Conclude Students should present an analysis of their data and some conclusion.

Chapter Key Concepts Builder (page 53)Students should work cooperatively to complete the activity. Student demonstrations should show how mechanical or chemical weathering affects soil formation, recognize that the process takes a long time, and show how properties are used to observe and measure soil. Demonstrations do not need to be elaborate, but they should indicate a good understanding of the relationship between weathering and soil formation.

Chapter Test A (page 54)Multiple Choice 1. B

2. B

3. A

4. B

5. C

6. C

7. C

Chapter Test A (page 55)Matching 8. F

9. B

10. C

11. D

12. A

13. E

Interpreting a Diagram 14. From top to bottom, the horizons should be

labeled A, B, C.

15. The O should be on the A-horizon.

16. The P should be on the bedrock at the bottom of the C-horizon.

Chapter Test A (page 56)Short Answer 17. Plant roots can grow through cracks in rocks.

As the roots get bigger, they push on the cracks and break the rocks into smaller pieces. Animals create holes in soil that allow water to enter and cause weathering. Animals also burrow through loose rocks, breaking them down as they dig.

18. Weathering occurs slowly in cold, dry places, such as deserts and polar regions. It occurs

quickly in wet, warm places, such as tropical forests.

19. From largest to smallest: sand, silt, clay. Sand allows water to flow easily through it because it has the largest pore spaces.

20. Students can explain any two of these five—parent material, climate, biota, topography, and time.

Concept Application 21. The rocks have probably undergone chemical

weathering. Acid rain could have contributed to the wearing away of the rock as well.

Chapter Test B (page 57)Multiple Choice 1. B

2. C

Matching 3. H

4. A

5. D

6. I

7. C

8. K

9. F

10. E

11. G

Chapter Test B (page 58)Interpreting a Diagram 12. Students should label the C-horizon (bottom)

as the least developed.

13. Students should label the A-horizon (top) as the most developed.

14. Students should identify the middle horizon as the B-horizon. It is rich in clay minerals and other materials transported from the A-horizon.

15. The C-horizon is most like the parent material because it is the least altered layer in the soil.

Short Answer 16. Both are present in different amounts in

different soils. Inorganic soil components are materials, such as minerals, that were never alive. Organic soil components are materials that are alive or were once alive. Organic components include plant parts, insects and other animals, animal wastes, and bacteria.

Chapter Test B (page 59) 17. Mechanical weathering breaks rock into smaller

pieces, which have greater surface area than the original rock. Because chemical weathering works on the surface of rock, greater surface area speeds chemical weathering.

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Answers continued 18. Possible answer: Chemical weathering requires

water and warm temperatures. Therefore, chemical weathering is more effective in warm, tropical climates where abundant water easily dissolves substances than in dry climates, which have little or no water.

Concept Application 19. Answers will vary. Examples of mechanical

weathering might include ice wedging, abrasion, and plant roots breaking apart rocks. Examples of chemical weathering might include oxidation (rusting), dissolving, or rocks worn down by acid rain.

20. A soil rich in organic matter would be dark (brown or black) in color. The presence of clay would make its texture sticky when it is wet. The presence of clay would also mean tiny pore spaces, making the infiltration rate of such a soil very slow.

21. Answers will vary. Possible answer: A farmer might look for a dark soil, which indicates that the soil is rich in organic matter. The farmer might evaluate the consistency of a soil. A softer soil is easier to plow than a harder one. The farmer might also evaluate the infiltration rate of the soil to see how it accepts and holds moisture.

Chapter Test C (page 60)Multiple Choice 1. A

2. C

3. A

4. B

5. B

Completion 6. composition

7. infiltration

8. oxidation

9. Temperature

Chapter Test C (page 61) 10. texture

11. consistency

12. structure

13. fertility

Interpreting a Diagram 14. Student drawings should show three horizons.

The C-horizon should be a bit thicker than the other two and should contain unweathered bedrock (parent material). The B-horizon should include a few large pieces of bedrock. Students should also indicate an abundance of clay in the B-horizon. A-horizon should contain no large rocks, but students can include organic matter such as plant roots or worms.

15. Possible answers: The A-horizon is the most developed layer. It contains the most organic matter, making it darker in color and excellent for plant growth. The B-horizon contains weathered materials, including clays, which were carried down from the A-horizon by rain or melted snow. A small amount of unweathered parent material is present in the B-horizon. The C-horizon is the least weathered layer. Much of it is parent material.

Chapter Test C (page 62)Short Answer 16. Mechanical weathering requires many cycles of

wet and dry or freezing and thawing. Thus, it is most effective in locations that have frequent temperature changes. Most chemical weathering requires moisture and warmth. Thus, it is most effective in areas that are wet and warm.

17. Organic matter is important because it provides plants with nutrients, it holds water, and it helps keep soil pores open.

18. Clay is often washed from the A-horizon into the B-horizon by rain or melted snow.

Concept Application 19. A soil rich in clay is more fertile than a soil rich

in sand because smaller clay particles have greater surface area and smaller pore spaces. This allows clay to retain water (and any substances the water contains) much better than sand.

20. Students should reason that the cold climate of high mountain areas would reduce the weathering of bedrock. If weathering formed a thin layer of soil, rain or melted snow would probably wash it down steep slopes.

21. Water is essential for chemical weathering because most substances dissolve in water. With a limited water supply in deserts, mechanical weathering would be more important in breaking down rock.



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