Weathering and Erosion Guide - GVLIBRARIES.ORG

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Teacher's Guide

Weathering

Editors:Brian A. Jerome, Ph.D.Stephanie Zak Jerome

Assistant Editors:Anneliese BrownLouise Marrier

Graphics:Fred Thodal

Lyndsey CanfieldDean Ladago

and Erosion

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Table of Contents2

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A Message from our Company

Viewing Clearances

Use and Copyright

National Standards Correlations

Student Learning Objectives

Assessment

Introducing the Program

Program Viewing Suggestions

Video Script

Answer Key to Student Assessments

Answer Key to Student Activities

Pre-Test

Post-Test

Video Review

Vocabulary

Writing Activity

Shake it Up!

A Rock’s Journey

Neighborhood Weathering

Landslides


National Standards CorrelationsBenchmarks for Science Literacy(Project 2061 - AAAS)

National Science Education Standards(Content Standards: K-4, National Academy of Sciences, c. 1996)

Grades 3-5

Earth and Space Science (D) - Structure of the Earth System

By the end of the fi fth grade, students should know that:The Physical Setting - Processes that Shape the Earth (4C)

• Waves, wind, water, and ice shape and reshape the earth’s land surface by eroding rock and soil in some areas and depositing them in other areas, sometimes in seasonal layers.

• Rock is composed of different combinations of minerals. Smaller rocks come from the breakage and weathering of bedrock and larger rocks. Soil is made partly from weathered rock, partly from plant remains - and also contains many living organisms.

Earth and Space Science (D) - Changes in Earth and SkyAs a result of activities in grades K-4, all students should develop an understanding of:

• The surface of the earth changes. Some changes are due to slow processes, such as erosion and weathering, and some changes are due to rapid processes, such as landslides, volcanic eruptions, and earthquakes.

As a result of activities in grades 5-8, all students should develop an understanding of:

• Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion.


Student Learning ObjectivesUpon viewing the video and completing the enclosed student activities, stu-dents will be able to do the following:

• Describe weathering as a process that involves the breaking down of rocks and other materials on Earth’s surface.

• Differentiate between the processes of mechanical weathering and chemical weathering.

• Defi ne mechanical weathering as the process by which rocks or other

materials are physically changed, but not chemically changed.

• List examples of ways mechanical weathering occurs, including abrasion, temperature fl uctuations, landslides, freezing and thawing, and the action of plant roots.

• Explain that chemical weathering is the process by which the actual

composition, or chemical makeup, of a rock is changed in to a different substance.

• Provide examples of chemical weathering, including the effect of water, air, acid rain, oxidation, and plants on rocks.

• Defi ne erosion as the process by which earth materials are moved from one

place to another.

• List and describe some agents of erosion, such as the following: moving water, waves, wind, and glaciers.

• Provide and describe some common examples of agents of erosion near your

home.


The Post-Test can be utilized as an assessment tool following student completion of the program and student activities. The results of the Post-Test can be compared against the results of the Preliminary Test to assess student progress.

The Preliminary Test is an assessment tool designed to gain an understanding of students’ preexisting knowledge. It can also be used as a benchmark upon which to assess student progress based on the objectives stated on the previous pages.

Assessment

Preliminary Test (p. 14-15):

Video Review (p. 18):

Post-Test (p. 16-17):

The Video Review can be used as an assessment tool or as a student activity. There are two sections. The fi rst part contains questions displayed during the program. The second part consists of a fi ve-question video quiz to be answered at the end of the video.


Introducing the Program

Program Viewing SuggestionsThe student master “Video Review” is provided (p. 18) for distribution to students. You may choose to have your students complete this Master while viewing the program or do so upon its conclusion.

The program is approximately 14 minutes in length and includes a fi ve-question video quiz. Answers are not provided to the Video Quiz in the video, but are included in this guide on page 12. You may choose to grade student quizzes as an assessment tool or to review the answers in class.

The video is content-rich with numerous vocabulary words. For this reason you may want to periodically stop the video to review and discuss new terminology and concepts.

Before viewing the program, write the term “weathering” on the board. Explain to students that weathering involves the breaking down of rocks and other materials on Earth. Ask students to list some examples of weathering they have observed around the school. Write their examples on the board. Next, write the following terms on the board: “mechanical weathering” and “chemical weathering.” Explain that in mechanical weathering, rocks are physically broken down, but the actual chemical composition of the rock does not change. In chemical weathering, the actual makeup, or chemical composition, of a rock is changed. Next to each example of weathering, state if it is the result of mechanical weathering, chemical weathering, or both.

If time remains, conduct the following simple demonstration illustrating the difference between mechanical weathering and chemical weathering. Take a piece of chalk and break it in half. Break the pieces of chalk in half again. Tell students this is an example of mechanical weathering. Then, hold up a new shiny nail, and an old, rusty nail. Ask students what happened to the old nail. This is an example of chemical weathering called oxidation. Tell students to pay close attention to the video to learn more about weathering.


Video Script 1. What force was responsible for sculpting these unusual formations in southern

Utah? 2. What caused this rock to fall from the overhanging cliff? 3. What force caused the tombstone in this graveyard to become nearly illegible? 4. And how was the sand in these dunes transported here? 5. During the next few minutes, we are going to try to answer these questions and

others... 6. ...as we investigate the very important and powerful forces of weathering... 7. ...and erosion. 8. Graphic Transition – What is Weathering? 9. Every time you go outside, you experience the weather.10. Weather is the condition of the atmosphere.11. The process of weathering, however, is different.12. Weathering involves the breaking down of rocks and other materials on Earth’s

surface.13. The process of weathering is occurring all around us, even though we may not

realize it.14. But, we can easily see the effects of weathering.15. Over the years, weather has taken a toll on this old house.16. Weathering is responsible for rusting this car.17. And weathering broke down these large rocks into smaller pieces.18. There are two major types of weathering: mechanical weathering and chemical

weathering.19. Let’s take a look fi rst at mechanical weathering.20. Graphic Transition – Mechanical Weathering21. You Predict! What will happen when you hit this brick with a hammer?22. The brick breaks into smaller pieces.23. Mechanical weathering works in a similar way. In the process of mechanical

weathering, rocks or other materials are physically changed, but are not chemically altered.

24. In other words, rocks are broken into smaller and smaller pieces, but the makeup of the rock stays the same.

25. This sort of weathering can even change the size and shape of Earth’s surface.26. For instance, the downward pull of gravity on rocks is an important force causing

rocks to fall and break apart.27. Sometimes landslides occur, causing large parts of the Earth’s surface to move

downhill.28. Rocks also rub against each other in a process called abrasion.29. Abrasion causes rocks to become less jagged, smaller, and more rounded.30. This often occurs in rivers and streams.31. Abrasion also results when wind-blown sand scours landforms.


Video Script32. Temperature changes can also weather rocks.33. Fluctuations between hot and cold temperatures cause rocks to continually

expand and contract, eventually causing them to split apart.34. Here in Yosemite National Park, large sheets of rock periodically fl ake off due to

heating and cooling.35. The freezing and thawing of water can also mechanically weather rocks.36. You Predict! What will happen to this glass bottle of water when placed in the

freezer overnight?37. As you can see, the water froze and the bottle broke.38. When water freezes, it expands. In this case, the water expanded so much that it

broke the glass bottle.39. A similar process occurs here in Bryce Canyon National Park.40. These unusual columns of rocks, called hoodoos, are formed in part due to the

freezing and thawing of water.41. When water in cracks freezes, it expands and widens the cracks.42. Moving water from snowmelt and rain storms causes further weathering,...43. ...and carries away rock particles. Occasionally huge pieces of rock fall in to the

canyon fl oor.44. The cracks you see in sidewalks and roads are often caused by freezing and

thawing.45. The roots of trees and other plants sometimes penetrate cracks in rocks as well.46. And as roots expand over time, they force cracks farther apart, eventually

breaking the rocks.47. These are just a few examples of some of the more common forces of mechanical

weathering.48. Graphic Transition – Chemical Weathering49. This rusty nail...50. ...and this stone monument have experienced another type of weathering called

chemical weathering.51. In the process of chemical weathering, the actual composition, or chemical

makeup, of a rock is changed into a different substance.52. Air, water, and other substances react with rocks to alter them.53. Water is one of the most prevalent agents of chemical weathering.54. Over time, this process causes rocks to decompose or break down.55. You Observe! What happens to these halite rock fragments when stirred in

water?56. Halite, the rock from which table salt is made, dissolves in water.57. Water can dissolve many minerals that hold rocks together.58. Water can also form acids when mixed with some gases in the air.59. Acids often speed up the decomposition of rocks.60. Certain types of air pollution can often make rainwater quite acidic, forming what’s

called acid rain.


Video Script61. Acid rain accelerates the weathering of rocks.62. If you have ever left a metal tool or other metal object out in the rain, you’ve seen

the effects of another type of weathering called oxidation.63. Oxidation is the process of oxygen combining with a chemical to produce a new

substance.64. The orange coloring seen on this nail, called rust, is the product of oxidation.65. Oxygen in the air reacted with iron in the nail.66. Often, rocks that contain iron also undergo oxidation, giving them an orangish

color.67. Living things, such as plants and plant-like organisms, can also chemically

weather rocks.68. For example, these living things, called lichens, release weak acids that weather

rocks.69. Similarly, the roots of plants produce acids that, over time, decompose rocks.70. It is important to realize that chemical weathering and mechanical weathering

often work together to break down earth materials.71. Graphic Transition – What is Erosion?72. This stream is carrying out erosion.73. Erosion is a process by which earth materials, such as weathered rock and soil

particles, are moved from one place to another.74. There are many different ways earth materials are transported. These different

ways are referred to as agents of erosion.75. Let’s take a closer look at some examples of agents of erosion.76. This glass of water was taken from this rushing river. Notice how dirty the water

looks.77. If we let the glass sit still for a few hours, the sediments settle to the bottom.78. You Decide! Where did the sediment come from?79. As water moves across the surface of land in a process called runoff, it carries

sediments into rivers and other bodies of water.80. Moving water is the most common powerful agent of erosion.81. Rivers, streams, and creeks are examples of moving water.82. It’s estimated that the Mississippi River transports over 500 million tons of

sediment each year.83. Waves are the major force of erosion along coasts.84. At this very moment, waves on this beach are transporting tons of sand, steadily

moving it along the coast.85. Wind is also a signifi cant agent of erosion.86. Wind can carry large amounts of sediments, including sand.87. In Death Valley, California, for example, strong winds move sand particles,...88. ...which are deposited here, forming sand dunes.89. This large fi eld of ice and snow is a glacier. Glaciers are actually moving sheets

of ice and snow.


Video Script 90. As glaciers slowly move, they carry out erosion by moving fragments of rock,

boulders, and other debris. 91. The dirt you see here is actually sediments eroded by the glacier. 92. When parts of the glacier melt, large deposits of rock, boulders, and sediment

are formed. 93. Graphic Transition – Summing Up 94. During the past few minutes, we have discussed some of the aspects of

weathering and erosion. 95. We learned that weathering involves the breaking down of rocks and other earth

materials. 96. Some of the aspects of mechanical weathering were explained,... 97. ...as were the ways chemical weathering breaks down rocks. 98. We then discussed erosion, the process by which Earth’s materials are moved

from one place to another. 99. And some of the major agents of erosion, including moving water, wind, waves,

and glaciers, were briefl y investigated. 100. So the next time you walk across a weathered sidewalk,...101. ...notice a rusty nail,...102. ...or observe a stream carrying sediment,...103. ...think about some of the things we’ve discussed during the past few minutes. 104. You just might think about weathering and erosion a little differently.105. Graphic Transition – Video Assessment

Fill in the correct word to complete the sentence. Good luck and let’s get started. 1. _______ involves the breaking down of rocks. 2. In the process of ________ weathering rocks are only physically changed. 3. Oxidation is an example of _____ weathering. 4. _______ is the movement of Earth materials from one place to another. 5. Moving ______ is the most common, powerful agent of erosion.

Answers can be found on page 12.


Answer Key to Student AssessmentsPre-Test (p. 14-15) Post-Test (p. 16-17)

Video Review (p. 18)1. When the brick is hit with the hammer, it breaks into smaller pieces.2. The glass bottle broke when the water froze and expanded.3. Halite, the rock from which table salt is made, dissolves in water.4. The sediment came from water moving across the surface of the land in a process called runoff.

1. b - weathering 2. a - physically 3. c - abrasion 4. a - freezing and thawing 5. d - chemical weathering 6. c - oxidation 7. d - erosion 8. b - runoff 9. a - wave action10. d - moving water11. true12. false13. true14. false15. true16. During the process of mechanical weathering, rocks are broken into smaller and smaller pieces, but the makeup of the rock stays the same.17. Some common examples of mechanical weathering are freezing and thawing, and abrasion.18. During the process of mechanical weathering, the chemical makeup of the rock is not changed. In chemical weathering, the chemical makeup of the rock changes causing it to form a different substance. 19. Earth materials are moved from one place to another in the process of erosion. Weathering breaks down earth’s materials.20. Rivers, streams, and creeks act as agents of erosion by moving sediment from one place to another.

1. a - wave action 2. a - freezing and thawing 3. b - runoff 4. c - abrasion 5. d - moving water 6. b - weathering 7. d - chemical weathering 8. a - physically 9. d - erosion10. c - oxidation11. false12. true13. true14. true15. false16. During the process of mechanical weathering, the chemical makeup of the rock is not changed. In chemical weathering, the chemical makeup of the rock changes causing it to form a different substance. .17. Rivers, streams, and creeks act as agents of erosion by moving sediment from one place to another. 18. During the process of mechanical weathering, rocks are broken into smaller and smaller pieces, but the makeup of the rock stays the same.19. Some common examples of mechanical weathering are freezing and thawing, and abrasion.20. Earth materials are moved from one place to another in the process of erosion. Weathering breaks down earth’s materials.

1. weathering 2. mechanical3. chemical 4. erosion 5. water


In Your Own Words (p. 20)

Writing Activity (p. 20)

Vocabulary (p. 19 )

Answer Key to Student Activities

1. weathering 2. mechanical weathering 3. abrasion 4. chemical weathering 5. acid rain 6. oxidation 7. rust 8. erosion 9. glacier10. moving water

Weathering involves the breaking down of Weathering involves the breaking down of Weatheringrocks and other materials on Earth’s surface. There are two major types of weathering. In the process of mechanical weathering, rocks are physically changed, but not chemically altered. Abrasion is the process in which rocks rub against each other, becoming more rounded and less jagged. In the process of chemicalweathering, the actual composition of a rock is changed into a new substance. Oxidation is an example of chemical weathering in which oxygen combines with iron and forms rust. Living things, such as tree roots and lichens, can also chemically alter rocks. Erosion is the process by which sand, silt, rocks, and sediments are moved from one place to another. Moving water is the most powerful agent of water is the most powerful agent of watererosion. Wind and glaciers are also agents of Wind and glaciers are also agents of Winderosion.

Shake it Up (p. 21)1. The more times the rocks are shaken, the smoother their surface.2. The more times the rocks are shaken, the smaller they become.3. The water became cloudy. As the rocks weather, small particles break off, clouding the water.4. Mechanical weathering caused the rocks to change.5. This process could occur in a river, stream, or ocean.

Neighborhood Observations (p. 23)Answers will vary. Examples include rust on a car (chemical weathering, caused by oxidation); rock fragments (mechanical weathering, can be caused by abrasion in a river); and cracks in sidewalks (mechanical weathering, caused by freezing and thawing).

Landslides (p. 25)1. Landslides can move between 48 an 80 kilometers per hour, and can travel as fast as 320 kilometers per hour.2. Gravity is the primary force responsible for landslides. 3. A landslide is the downward and outward movement of a large amount of rock or soil.4. Earthquakes, volcanic eruptions, heavy rainfall, and erosion by rivers, ocean waves, and glaciers can cause slopes to weaken and become too steep.5. A large landslide occurred in Washington when Mount St. Helens erupted.6. Communities prone to landscapes can develop evacuation plans. They can also not allow building on areas prone to landslides. 7. Landslides are more likely to occur in British Columbia in Canada; Alaska, Hawaii, California, Washington, and Oregon in the United States; and Colima State in Mexico.

1. Buildings, roads, and sidewalks undergo mechanical weathering from the action of water, freezing and thawing, and vibration of moving cars. Acid rain also causes chemical weathering.2. Mechanical weathering involves physically breaking down rocks into smaller and smaller pieces. Chemical weathering involves breaking down rocks by altering the actual chemical makeup of the rock.3. Erosion commonly occurs in most places where moving water or wind transports sediments from one place to another.

d. clouds

d. photosynthesis

d. chemical weathering

d. metamorphosis

Pre-Test

4. Which of the following is an example of a process that causes mechanical weathering of rocks?

5. Acid rain causes the following type of weathering:

1. The breaking down of rocks and other earth materials is called:

2. How does mechanical weathering change rocks?

3. The process of rocks rubbing together, causing them to become smaller and more rounded, is called:

Circle the best answer for each of the following questions.

a. evaporation b. weathering c. consolidation

a. freezing and thawing

c. equally

c. abrasion d. oxidation

a. physical weathering

b. mechanical weathering

c. sedimentation d. condensing and sublimating

b. crystallization

b. rounding

c. low impact weathering

a. physically

a. erosion

b. chemically d. synergistically

6. Rust is the result of which process?

a. sublimation b. erosion c. oxidation

10. In wet environments, the major cause of erosion is:

d. evaporation

d. erosion

7. What is the name of the process by which earth materials, such as stones and soil particles, are moved from one place to another?

8. The process of water moving across the surface of the land is called:

9. The major cause of erosion along coasts is:

a. rain

c. chemical weathering

a. wave action b. tornadoes

c. precipitation b. runoff

b. weathering

c. earthquakes

a. condensation

a. wind b. animal movement c. air movement d. moving water

Visual Learning Company

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14Weathering and Erosion

Name

Write a short answer for each of the following.

Pre-Test

16. Describe the process of mechanical weathering in your own words.

17. Identify two common examples of mechanical weathering that occur near your home or school.

18. Explain how chemical weathering is different from mechanical weathering.

11.

12.

13.

14.

15.

Write true or false next to each statement.

19. What is the difference between weathering and erosion?

20. Describe how moving water acts as an agent of erosion.

It is possible to see the effects of weathering.

Mechanical weathering and chemical weathering are the same processes.

Mechanical weathering and chemical weathering often work together.

Rust is a product of mechanical weathering.

There are several different agents of erosion.


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Circle the best answer for each of the following questions.

Post-Test

9. What is the name of the process by which earth materials, such as stones and soil particles, are moved from one place to another?

7. Acid rain causes the following type of weathering:

6. The breaking down of rocks and other earth materials is called:

4. The process of rocks rubbing together, causing them to become smaller and more rounded, is called:

1. The major cause of erosion along coasts is:

10. Rust is the result of which process?

8. How does mechanical weathering change rocks?

2. Which of the following is an example of a process that causes mechanical weathering of rocks?

5. In wet environments, the major cause of erosion is:

3. The process of water moving across the surface of the land is called:

c. earthquakes b. tornadoes

d. metamorphosis a. evaporation

a. wave action d. clouds

a. freezing and thawing

c. sedimentation b. crystallization d. condensing and sublimating

d. evaporation a. rain c. precipitation b. runoff

c. abrasion d. oxidation b. rounding a. erosion

a. wind b. animal movement c. air movement d. moving water

b. weathering c. consolidation

d. chemical weathering

a. physical weathering

b. mechanical weathering

c. low impact weathering

c. equally a. physically b. chemically d. synergistically

d. erosion c. chemical weathering

b. weathering a. condensation

d. photosynthesis a. sublimation b. erosion c. oxidation


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Post-Test

Write a short answer for each of the following.

20. What is the difference between weathering and erosion?

18. Describe the process of mechanical weathering in your own words.

17. Describe how moving water acts as an agent of erosion.

11.

12.

13.

14.

15.

Write true or false next to each statement.

16. Explain how chemical weathering is different from mechanical weathering.

19. Identify two common examples of mechanical weathering that occur near your home.

Rust is a product of mechanical weathering.

There are several different agents of erosion.

It is possible to see the effects of weathering.

Mechanical weathering and chemical weathering often work together.

Mechanical weathering and chemical weathering are the same processes.


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Name

1. What will happen when you hit this brick with a hammer?

3. Oxidation is an example of ________________ weathering.

2. In the process of __________________ weathering rocks are only physically changed.

1. ________________ involves the breaking down of rocks

After you watch the video, test your knowledge with these questions.

While you watch the video, answer these questions:

2. What will happen to this glass bottle of water when placed in the freezer overnight?

3. What happens to these halite rock fragments when stirred in water?

Video Review

You Predict!

You Observe!

You Predict!

4. Where did the sediment come from?

You Decide!

4. ______________ is the movement of earth materials from one place to another.

5. Moving _________ is the most common, powerful agent of erosion.


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Name

VocabularyUse these words to fi ll in the blanks next to the sentences below.

1.

7.

2.

6.

8.

4.

5.

3.

9.

10.

Wo

rds

The breaking down of rock and other materials on Earth’s surface.

The process of rock breaking down physically, but not chemically.

This occurs when rocks rub against each other, becoming less jagged and more rounded.

A type of weathering in which a rock is changed into a different substance.

Precipitation that often causes chemical weathering.

The process of oxygen combining with a chemical to form a new substance.

The process that results from oxidation and produces an orange color seen on iron rocks or objects.

The movement of weathered rock, sediments, or particles from one place to another.

Large moving sheet of ice and snow that has the ability to erode rock.

The most common, powerful agent of erosion.

weathering

mechanical weathering

abrasionchemical weathering

acid rain

oxidation

rust

erosion

glaciermoving water


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Name

2. Explain the difference between mechanical weathering and chemical weathering.

1. Describe an example of weathering in your neighborhood.

Use the correct word from above to complete the sentences in the following paragraph.

Writing Activity

In Your Own Words

3. How does erosion occur near your home?

________________ involves the breaking down of rocks and other materials on Earth’s surface. There are two major types of weathering. In the process of ______________weathering, rocks are physically changed, but not chemically altered. ______________is the process in which rocks rub against each other, becoming more rounded and less jagged. In the process of ________________ weathering, the actual composition of a rock is changed into a new substance. ________________ is an example of chemical weathering in which oxygen combines with iron and forms ________________. ________________ things, such as tree roots and lichens, can also chemically alter rocks. ________________ is the process by which sand, silt, rocks, and sediments are moved from one place to another. Moving ________________ is the most powerful agent of erosion. ________________ and glaciers are also agents of erosion.

weatheringmechanical abrasion

chemicaloxidation

rustliving

erosion waterwind

Wo

rds


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Shake It Up!Background: Many of the smaller rocks you see around your school were once much larger rocks. How did they get to be so small? Larger rocks break into smaller rocks as a result of a process called weathering. Weathering involves the breaking down of rocks and other materials on Earth’s surface. There are two major types of weathering: mechanical and chemical. In this activity, you will learn more about mechanical weathering. Mechanical weathering is the process by which rocks or other materials change physically, but not chemically.

Materials:Large, clean plastic mayonnaise jar with lid24 pieces of limestone, approximately the same sizewater8 index cardssomething to write with

Activity:1. Write the following numbers on an index card, using one index card per number: 0, 100, 200, 300, 400, 500, 600, and 700. These numbers indicate the number of times you will shake the mayonnaise jar. 2. Arrange the cards on a large, fl at surface, leaving space to place 3 rocks below each index card.3. Place three of the limestone rocks under the index card marked 0.4. Place the remaining 18 rocks in the mayonnaise jar and fi ll half of the jar with water.5. Place the lid on the jar and make sure it is sealed tightly. Quickly shake the jar 100 times. Then remove three of the rocks and place under the index card marked 100.6. Repeat step 5 for each of the index cards until three rocks have been place beneath all of the cards.7. Observe the 8 piles of rocks. Notice how the piles are similar to and different from one another.

Questions:1. Compare the surface of the piles of rocks. How does the surface change based on the number of times the rocks were shaken?2. Compare the size of the piles of rocks. How does the size change based on the number of times the rocks were shaken?3. Did the water change by the end of the experiment? If so, how? Why do you think this occurred?4. What is the name of the process that caused the rocks to change size, texture, and shape?5. Where might this type of similar process happen in the natural world?


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A Rock’s Journey

Background: If you have ever been to a beach, you have probably noticed that there are many different sizes of rocks - some are very large and some are small pebbles. Many of these rocks were broken down by the processes of mechanical and chemical weathering. In mechanical weathering, rocks are physically altered, changing their size and shape. With chemical weathering, the chemical makeup of the rock changes. In some cases, the broken down rocks are transported thousands of kilometers. Where did the rocks come from and how did they travel such great distances? Some started at the peaks of distant mountains and were carried to the ocean as a result of erosion. Erosion is the process by which earth materials are moved from one place to another. Rivers, waves, wind, and glaciers are all agents of erosion.

Activity: On a separate piece of paper, write a story about a rock that has undergone weathering and has been moved via the process of erosion. Your rock’s journey will begin at the top of a tall mountain and end at a beach on a distant ocean. Answer the following questions in your story:

1. Where did your rock begin its journey?2. What did your rock look like when it started? How has its size changed? Its texture? Has it changed chemically? What forces caused it to change?3. How did your rock get to the ocean? Was it carried there by a fast moving river, the wind, a wave, a glacier, or a combination of these forces?4. What was the rock’s favorite part of its journey? Is there a place it liked visiting the most?5. What was the scariest part of the rock’s journey? The most fun part? 6. How long did the rock’s journey take?


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NeighborhoodWeathering Background: Weathering is the process by which rocks and other materials on Earth’s surface are broken down. There are two primary types of weathering: mechanical and chemical. Mechanical weathering is the process by which rocks are physically changed, but their actual composition remains the same. Examples include changes in size and texture. Mechanical weathering can occur as a result of abrasion, temperature fl uctuations, landslides, and the action of plant roots. Chemical weathering is the process by which the chemical makeup of a rock is changed into a different substance. Chemical weathering occurs as a result of water dissolving materials, air reacting with materials, acid rain, oxidation, and plant activity on materials.

Example of weathering Type of weathering(mechanical or chemical)

Cause of weathering

Directions: Find examples of weathering around your neighborhood. Use these examples to fi ll in the chart. Identify if it is an example of chemical or mechanical weathering and describe the cause of weathering.


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Landslides

Directions: Read the information below and answer the questions on the following page.

Have you ever been riding in a car and seen a sign that says “Watch for Falling Rocks?” If so, you were probably in an area that is prone to landslides. The term “landslide” is used to describe the downward and outward movement of a large amount of rock or soil. Rocks falling, sliding, and fl owing are all landslide actions. The speed of landslides can range from 48 to 80 kilometers per hour, with some reaching 320 kilometers per hour.

Most landslides are due to gravity. At some point, the slope on which soil and rock exists becomes too steep and weak, causing rock and soil to begin moving downward and outward. Several factors can weaken slopes and cause them to become too steep, such as erosion by rivers, ocean waves, and glaciers. Slopes can also be weakened by heavy rainfall, when there is more water than the soil can absorb. Earthquakes can weaken slopes. Volcanic eruptions are capable of producing debris fl ows, known as lahars, which pick up a lot of materials and speed as they move, making them particularly dangerous. Landslides can also be caused by human activity. Roadwork, blasting, mining, and logging can all weaken the soil on a slope.

Landslides have the potential to cause severe damage, depending on the size and location of the landslide. If a landslide gains enough speed and mass, it can take out trees, cars, houses, and even parts of villages. In 1998, torrential rain fell in Honduras, Guatemala, Nicaragua, and El Salvador, causing landslides throughout the region that killed approximately 10,000 people. A very large landslide occurred in the aftermath of the eruption of Mount St. Helens in Washington state in 1980. Fortunately, only 5-10 people died as a result of the landslide because the areas near the volcano were evacuated. However, many homes, highways, and buildings were destroyed.

Are certain areas more prone to landslides? The answer is yes. Landslides are more likely to occur in areas with steep slopes, such as mountainous, volcanic, and coastal regions. The areas of the United States, Canada, and Mexico most commonly affected by landslides include British Columbia in Canada; California, Oregon, and Washington in the United States; and the Colima State in Mexico. Alaska and Hawaii are also commonly affected.

Landslides occur all over the world. It is important to fi nd out if you live near an area that is prone to landslides. The best place to get this information is through your Geological Survey offi ce. Communities can also protect themselves from the devastating effects of landslides by creating evacuation plans in the event of landslides, and by not building in areas that are prone to landslides.


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Directions: Use the information on the previous page to answer the questions below.

1. How fast can landslides move?

2. What is the primary force responsible for landslides?

3. What is a landslide?

4. List four natural occurrences that can cause slopes to weaken and become too steep.

5. Give an example of a large landslide that occurred in North America. What caused this?

6. What can a community do to prepare for and protect itself from a landslide?

7. In what areas of the U.S., Canada, and Mexico are landslides more likely to occur?

Landslides


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Documents

Weathering and Erosion Guide - GVLIBRARIES.ORG