Weathering. Teacher's Guide. and Erosion. Visual Learning Company Editors: Brian A. Jerome, Ph.D. Stephanie Zak Jerome

Transcription

1 Weathering and Erosion Teacher's Guide Editors: Brian A. Jerome, Ph.D. Stephanie Zak Jerome Assistant Editors: Anneliese Brown Louise Marrier Graphics: Fred Thodal Lyndsey Canfield Dean Ladago Union Street Brandon VT 05733

2 A Message from our Company... Visual Learning is a Vermont-based, family owned company specializing in the creation of science programs. As former classroom science teachers we have designed our programs to meet the needs and interests of both students and teachers. Our mission is to help educators and students meet educational goals while experiencing the thrill of science! Viewing Clearances The video and accompanying teacher s guide are for instructional use only. In showing these programs, no admission charges are to be incurred. The programs are to be utilized in face-to-face classroom instructional settings, library settings, or similar instructional settings. Duplication Rights are available, but must be negotiated with the Visual Learning Company. Television, cable, or satellite rights are also available, but must be negotiated with the. Closed circuit rights are available, and are defi ned as the use of the program beyond a single classroom but within a single campus. Institutions wishing to utilize the program in multiple campuses must purchase the multiple campus version of the program, available at a slightly higher fee. Discounts may be granted to institutions interested in purchasing programs in large quantities. These discounts may be negotiated with the. Use and Copyright: The purchase of this video program entitles the user the right to reproduce or duplicate, in whole or in part, this teacher s guide and the black line master handouts for the purpose of teaching in conjunction with this video,. The right is restricted only for use with this video program. Any reproduction or duplication, in whole or in part, of this guide and student masters for any purpose other than for use with this video program is prohibited. The video and this teacher s guide are the exclusive property of the copyright holder. Copying, transmitting, or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506). Copyright 2008 ISBN

3 Table of Contents 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

4 National Standards Correlations Benchmarks for Science Literacy (Project AAAS) Grades 3-5 The Physical Setting - Processes that Shape the Earth (4C) By the end of the fi fth grade, students should know that: 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. National Science Education Standards (Content Standards: K-4, National Academy of Sciences, c. 1996) Earth and Space Science (D) - Changes in Earth and Sky As 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. Earth and Space Science (D) - Structure of the Earth System 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

5 Student Learning Objectives Upon viewing the video and completing the enclosed student activities, students 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

6 Assessment Preliminary Test (p ): 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. Post-Test (p ): 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. Video Review (p. 18): 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

7 Introducing the Program 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. Program Viewing Suggestions The 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

8 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 as we investigate the very important and powerful forces of weathering 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 Weathering 21. 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

9 Video Script 32. 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, 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 Weathering 49. This rusty nail 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

10 Video Script 61. 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, 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

11 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, 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 So the next time you walk across a weathered sidewalk, notice a rusty nail, or observe a stream carrying sediment, think about some of the things we ve discussed during the past few minutes You just might think about weathering and erosion a little differently 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 Assessments Pre-Test (p ) Post-Test (p ) 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 action 10. d - moving water 11. true 12. false 13. true 14. false 15. true 16. 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 - erosion 10. c - oxidation 11. false 12. true 13. true 14. true 15. false 16. 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 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. 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. weathering 2. mechanical 3. chemical 4. erosion 5. water

13 Answer Key to Student Activities Vocabulary (p. 19 ) 1. weathering 2. mechanical weathering 3. abrasion 4. chemical weathering 5. acid rain 6. oxidation 7. rust 8. erosion 9. glacier 10. moving water Writing Activity (p. 20) Weathering involves the breaking down of rocks 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 chemical weathering, 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 erosion. Wind and glaciers are also agents of erosion. In Your Own Words (p. 20) 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. 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

14 Pre-Test Name Circle the best answer for each of the following questions. 1. The breaking down of rocks and other earth materials is called: a. evaporation b. weathering c. consolidation d. metamorphosis 2. How does mechanical weathering change rocks? a. physically 3. The process of rocks rubbing together, causing them to become smaller and more rounded, is called: a. erosion b. rounding c. abrasion d. oxidation 4. Which of the following is an example of a process that causes mechanical weathering of rocks? a. freezing and thawing b. chemically c. equally d. synergistically b. crystallization c. sedimentation d. condensing and sublimating 5. Acid rain causes the following type of weathering: a. physical weathering b. mechanical weathering 6. Rust is the result of which process? c. low impact weathering a. sublimation b. erosion c. oxidation d. chemical weathering d. photosynthesis 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? a. condensation 8. The process of water moving across the surface of the land is called: a. rain b. weathering b. runoff c. chemical weathering c. precipitation d. erosion d. evaporation 9. The major cause of erosion along coasts is: a. wave action b. tornadoes c. earthquakes d. clouds 10. In wet environments, the major cause of erosion is: a. wind b. animal movement c. air movement d. moving water 14

15 Pre-Test Name Write true or false next to each statement 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. Write a short answer for each of the following. 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. 19. What is the difference between weathering and erosion? 20. Describe how moving water acts as an agent of erosion. 15

16 Post-Test Name Circle the best answer for each of the following questions. 1. The major cause of erosion along coasts is: a. wave action b. tornadoes c. earthquakes d. clouds 2. Which of the following is an example of a process that causes mechanical weathering of rocks? a. freezing and thawing b. crystallization c. sedimentation d. condensing and sublimating 3. The process of water moving across the surface of the land is called: a. rain b. runoff c. precipitation d. evaporation 4. The process of rocks rubbing together, causing them to become smaller and more rounded, is called: a. erosion b. rounding 5. In wet environments, the major cause of erosion is: c. abrasion d. oxidation a. wind b. animal movement c. air movement d. moving water 6. The breaking down of rocks and other earth materials is called: a. evaporation b. weathering c. consolidation d. metamorphosis 7. Acid rain causes the following type of weathering: a. physical weathering b. mechanical weathering c. low impact weathering d. chemical weathering 8. How does mechanical weathering change rocks? a. physically b. chemically c. equally d. synergistically 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? a. condensation b. weathering 10. Rust is the result of which process? c. chemical weathering d. erosion a. sublimation b. erosion c. oxidation d. photosynthesis 16

17 Post-Test Name Write true or false next to each statement Rust is a product of mechanical weathering. It is possible to see the effects of weathering. There are several different agents of erosion Mechanical weathering and chemical weathering often work together. Mechanical weathering and chemical weathering are the same processes. Write a short answer for each of the following. 16. Explain how chemical weathering is different from mechanical weathering. 17. Describe how moving water acts as an agent of erosion. 18. Describe the process of mechanical weathering in your own words. 19. Identify two common examples of mechanical weathering that occur near your home. 20. What is the difference between weathering and erosion? 17

18 Video Review Name While you watch the video, answer these questions: You Predict! 1. What will happen when you hit this brick with a hammer? You Predict! 2. What will happen to this glass bottle of water when placed in the freezer overnight? You Observe! 3. What happens to these halite rock fragments when stirred in water? You Decide! 4. Where did the sediment come from? After you watch the video, test your knowledge with these questions. 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. 18

19 Vocabulary Name Use these words to fill in the blanks next to the sentences below. Words mechanical weathering erosion oxidation acid rain rust chemical weathering moving water weathering glacier abrasion 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. 10. The most common, powerful agent of erosion. 19

20 Writing Activity Name Words wind erosion mechanical weathering water abrasion oxidation living chemical rust Use the correct word from above to complete the sentences in the following paragraph. 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. In Your Own Words 1. Describe an example of weathering in your neighborhood. 2. Explain the difference between mechanical weathering and chemical weathering. 3. How does erosion occur near your home? 20

21 Shake It Up! Name 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 lid 24 pieces of limestone, approximately the same size water 8 index cards something 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 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 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? 21

22 A Rock s Journey Name 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? 22

23 Neighborhood Weathering Name 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. 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. Example of weathering Type of weathering (mechanical or chemical) Cause of weathering 23

24 Landslides Name 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 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. 24

25 Landslides Name 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? 25