ROCK SOLID Name: _______________________ Date: __________ ROCK SOLID Pre-Lesson Assessment (3 points) 1. 2. 3. Of what material(s) is the earth's crust made? _______________________________________________________________ How do rocks break in nature? ________________________________________________________________ How would the breaking of a large rock affect people? ________________________________________________________________ ________________________________________________________________ Part 1: Read We see rocks outside every day, in both landscaping and nature. In fact, the entire earth is basically one gigantic rock! The earth's crust is entirely made of solid rocks, so there are huge rocks in the ground covering the entire planet! We cannot see many of these rocks. Sometimes dirt covers them and we must dig very deep to find them, but huge rocks cover the entire earth's crust, even under the oceans. That means that all of our buildings, all of our bridges, all of our roads, and even your home, are sitting on rock. Part 2: View PPT http://www.woboe.org/cms/lib8/NJ01912995/Centricity/Domain/867/rock%20solid%20intro%20ppt.ppt Part 3: Predict (3 Points) The following are questions that geotechnical engineers think about when determining locations to place structures. Geotechnical engineers understand what causes rocks to break. They know how to identify different types of rocks, and determine if a certain rock is likely to break. They work with structural engineers to plan the best way to build structures in different rock conditions. 1. What might happen if some of these huge rocks broke? 2. What types of natural disasters might be caused? 3. What would happen to the bridge or skyscraper resting upon one of those massive rocks? ROCK SOLID Page 1 ROCK SOLID Part 4: Background Information: READ Why Care about the Strength of a Rock? The most important reason why we care about the strength of a rock is that when a large rock breaks, it can be a hazard and possibly cause a disaster. There are many different disasters caused by breaking rocks, including earthquakes, tsunamis, volcanoes, rock falls, and landslides. To protect structures and people, we want to be able to predict or prevent such disasters. If an engineer knows the characteristics of a particular rock type, she may be able to predict or prevent disasters. Furthermore, a less serious reason why we care about the strength of rocks is for development, which means building and expanding the use of land (such as new shopping centers, schools or homes being built in a town). Many building plans require deep foundations, making it necessary to excavate or dig out rock. An engineer provides information about the best way to excavate the rock, so as to build an adequate foundation. What Can Break Rocks? When pressure is applied to an area, such as a rock, it is called stress. If you press your hands together, you can feel the forces of stress. In nature, stress can cause rocks to break, and one way that stress occurs is by the natural movements of the earth's crust (remember that the earth's crust is basically floating on liquid magma, and so it moves often). There are three types of stress Figure 1. Three types of stresses in rocks. 1. Compressional stress is when a rock is pressed together into itself, like when crust movements cause two rocks to squeeze another one between them. Another example is when mountains are formed at a convergent boundary, like the Rocky Mountains. Press your hands together again. You can feel that the inner parts of your hands are being smashed by compressional stress from the muscles in your hands pushing inward. ROCK SOLID Page 2 ROCK SOLID 2. Tensional stress is when a rock is pulled apart. For example, if a rock wedged itself into the crack of another rock, and movement of the earth's crust caused it to wedge even further until the rock broke apart. Another example is a divergent boundary, like the Mid-Atlantic Ridge, which is formed by two tectonic plates pulling apart from each other to allow lava to flow upward. Use one of your hands to pull a finger on your other hand. You can feel the tensional stress because your hand is pulling your finger one way, and your other hand is attached to your finger, pulling it the other way by holding it in place. 3. Shear stress is when a rock is pulled on one side but pushed on the other side. This can happen if the crust movements on one side of a rock are opposite of those on the other side of the rock. An example of this is the San Andreas Fault, which is on a transform boundary, with the California plate moving southward and the Pacific Ocean plate moving northward. Put your hands together again, but this time press upward with your right hand and downward with your left hand. If you press hard, you should notice that the skin on your right hand is being pulled down because of the forces from your left hand pulling down, and the skin on your left hand is being pulled up because of your right hand. (It may be easier to see the skin being pulled if you use an area on your body where the skin is looser, such as your hand pressing upward against your arm or cheek.) In addition to stress due to the movement of the earth's crust, stress can come from weathering. Weathering is the breaking down of rocks into sediments (small bits of rock), due to conditions in nature. There are many types of weathering: Physical weathering is when a physical action breaks the rock, such as the forces of wind or water. A common example is the freeze/thaw action of water in rock cracks. As the water freezes, it expands, causing stress (pressure) that breaks the rock. (Note: If students ask what kind of stress this is, tell them that the process is complicated and includes both tensional and compressional stress.) Chemical weathering is when the rock is chemically broken down. Some common examples of this are rust forming on granite or acid rain breaking down limestone. This type of weathering is not considered a type of stress because there is no pressure on the rock (remember that stress is pressure applied to an area). Biological weathering is when living organisms break the rock. A typical example is a tree root breaking a rock due to the stress caused by its pressure. (Note: If students ask what kind of stress this is, tell them that the process is complicated and includes both tensional and compressional stress.) So, rocks in the earth are usually broken by either the stress from the movement of the crust or the stress from weathering. ROCK SOLID Page 3 ROCK SOLID Part 5: Lab Exploration Pressure on Rocks – Soapy Stress Lab Rocks cover the entire earth, and we need to know how they break. Who can tell me why? If we know how rocks break, then we can predict many types of natural hazards, which can, in turn, save structures or even our lives. Also, because we live on the earth and build structures on and in the earth, we need to know about how rocks break. Geotechnical engineers know all about rocks in the earth's crust. They know how to identify different rocks, and determine if a certain rock is likely to break. They do tests and simulations to predict volcanoes, earthquakes or rockslides. Geotechnical engineers also need to know how rocks break so that other engineers can excavate or dig into them to build the deep foundations or basements of buildings such as parking garages, bridge piers or skyscrapers. Do you know how rocks break? Well, rocks break from stress. Stress is when pressure is applied to an area, such as a rock. There are three types of stress. Compressional stress is when something is pressed together, like when mountains form. Tensional stress is when something is pulled apart, like when a ridge such as the Mid-Atlantic Ridge is formed. Shear stress is when something is pulled one way on one side and the other way on the other side, like the San Andreas Fault. Now that we've reviewed how rocks break, let's demonstrate these types of stresses ourselves! Using our own hands, do you think we could create enough stress to break a rock? Probably not! What are some things that we can break with our hands? Soap is a good model because with it, we can show the three different types of stress. Since we are not strong enough to break rocks, we can imagine that the bars of soap are rocks, and break them in different ways. Vocabulary/Definitions compressional stress: earth's crust: erosion: When something is being pressed together. Causes a rock to shorten. (geology) The exterior surface of the earth. Natural processes that wear away material. Includes weathering, dissolution, abrasion, corrosion and transportation. Geotechnical A person concerned with the engineering properties of earth materials. They engineer: investigate the soil and rock below ground to determine its properties, and then design foundations for human-made structures built on the ground, such as buildings or bridges. They design structures built in or of soil or rock. They also assess the risk to humans, property and the environment from natural hazards such as landslides, debris flows and rock falls. godel: A small object that represents another, often larger object. Often used in testing or perfecting a final product. rock: A naturally-formed aggregate of mineral matter constituting a significant part of the earth's crust. sedimentary rock: (geology) A rock made by the deposition of sediment (small bits of old rock). Examples: sandstone, siltstone, limestone and shale. shear stress: When something is being pulled one way on one side, and the opposite way on the other side. Causes rocks to slip past each other. stress: Pressure applied to an area. The three types are compressional, tensional and shear. tensional stress: When something is being pulled apart. Causes a rock to elongate, or pull ROCK SOLID Page 4 ROCK SOLID weathering: apart. Breaking down of rocks, due to such things as water, wind, acid rain and plants. Procedure MODEL #1 Tensional Stress (When something is being pulled apart.) 1. Choose one team member to place TENSIONAL STRESS on the bar of soap. Watch what happens carefully. Draw a picture of the soap and how it was broken. Draw arrows showing the direction of the force placed on the soap. (2 points) 2. Describe the area where the soap broke. (Smooth, rough, jagged, stretched, etc.) (2 Points) ________________________________________________________________________ 3. What is a real life example of tensional stress? (5 Points) ___________________________________________________________________________ ___________________________________________________________________________ Figure 1. Using tension (pulling apart movement) to break a bar of soap. ROCK SOLID Page 5 ROCK SOLID MODEL #2 COMPRESSIONAL Stress (When something is being pushed together.) 1. Choose one team member to place COMPRESIONAL STRESS on one of the pieces left from the bar of soap. Watch what happens carefully. Draw a picture of the soap and how it was broken. Draw arrows showing the direction of the force placed on the soap. (2 points) 2. Describe the area where the soap broke. (Smooth, rough, jagged, stretched, etc.) (2 points) ________________________________________________________________________ 3. What is a real life example of compressional stress? (5 Points) ___________________________________________________________________________ ___________________________________________________________________________ Figure 2. Using compression (pressed together pressure) to break soap. ROCK SOLID Page 6 ROCK SOLID MODEL #3 SHEAR Stress (When something is being pulled one way on one side, and the opposite way on the other side. Causes rocks to slip past each other.) 1. Choose one team member to place SHEAR STRESS on one of the pieces left from the bar of soap. Watch what happens carefully. Draw a picture of the soap and how it was broken. Draw arrows showing the direction of the force placed on the soap. (2 Points) 2. Describe the area where the soap broke. (Smooth, rough, jagged, stretched, etc.) (2 Points) ________________________________________________________________________ 3. What is a real life example of compressional stress? (5 Points) ___________________________________________________________________________ ___________________________________________________________________________ Figure 3. Using shear stress to break soap. One hand pulls up, the other hand pulls down. ROCK SOLID Page 7 ROCK SOLID MODEL #4 How might you demonstrate combination stresses using a piece of soap? (Clue: Try bending a bar of soap to cause both compressional and tensional stresses.) 1. Draw a picture of the soap and how it was broken. Draw arrows showing the direction of the force placed on the soap. (2 Points) 2. Describe the area where the soap broke. (Smooth, rough, jagged, stretched, etc.) (2 Points) ________________________________________________________________________ 3. What is a real life example of combination stress? (5 Points) ___________________________________________________________________________ ___________________________________________________________________________ ROCK SOLID Page 8 ROCK SOLID Assessment (6 Points) Matching: Match the correct pieces together. Journaling: Answer the following questions in paragraph form. 1. Today we demonstrated the three different types of stress. How would some of these stresses occur on a bigger scale in the natural world? BE SPECIFIC! (10 Points) _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 2. Why do geotechnical engineers need to understand stress in rocks? BE SPECIFIC! (Hint: think natural disasters, human made objects, etc.) (10 Points) _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ ROCK SOLID Page 9 ROCK SOLID Part 6: Interactive Explorations Kinds of Rocks and How Rocks Are Made 1. Go to: http://www.learner.org/interactives/rockcycle/types.html 2. Fill in this table: (9 Points) Name of Rock How it Forms Example 3. READ this chart Here's a chart of some of the key characteristics that can help you identify the rocks within these three main classes. Crystals Small, flat surfaces that are shiny or sparkly, like tiny mirrors. ROCK SOLID Fossils Imprints of leaves, shells, insects, or other items in the rock. Gas bubbles "Holes," like Swiss cheese, in the rock. Glassy surface A shiny and smooth surface, like colored glass. Ribbonlike layers Straight or wavy stripes of different colors in the rock. Sand or pebbles Individual stones, pebbles, or sand grains visible in the rock. Page 10 ROCK SOLID 4. START YOUR ROCK COLLECTION: Go to: http://www.learner.org/interactives/rockcycle/types2.html 5. Click on and read about each of the 6 rocks. WHEN YOU ARE DONE SHOW YOUR TEACHER for her initials. _____________ (Teacher Initials) (5 Points) 6. IDENTIFY ROCK TYPES: Go to: http://www.learner.org/interactives/rockcycle/types3.html 7. Play until you get 10 out of 10 correct. WHEN YOU ARE DONE SHOW YOUR TEACHER for her initials. _____________ (Teacher Initials) (10 Points) 8. HOW ROCKS CHANGE: Go to: http://www.learner.org/interactives/rockcycle/change.html Complete the three pages of the interactive. (Click next to go to each new page.) 9. Change a Rock Interactive Go to: http://www.learner.org/interactives/rockcycle/change4.html 10. Complete the interactive. WHEN YOU ARE DONE SHOW YOUR TEACHER for her initials. _____________ (Teacher Initials) (5 Points) 11. THE ROCK CYCLE DIAGRAM Go to: http://www.learner.org/interactives/rockcycle/diagram.html and read the diagram. 12. ROCK CYCLE DIAGRAM INTERACTIVE Go to: http://www.learner.org/interactives/rockcycle/diagram2.html 13. Play until you get 10 out of 10 correct. WHEN YOU ARE DONE SHOW YOUR TEACHER for her initials. _____________ (Teacher Initials) (10 Points) 14. TEST YOUR SKILLS Go to: http://www.learner.org/interactives/rockcycle/testskills.html 15. Take the test. If you score below and 80% refresh the page and do it again. WHEN YOU GET TO AT LEAST 80% SHOW YOUR TEACHER for her initials. _____________ (Teacher Initials) (10 Points) ROCK SOLID Page 11 ROCK SOLID Post Assessment Rock Cycle Diagram (20 Points) You may have noticed in learning about the different rock families that all new rocks are made from old rocks. This is the idea behind the rock cycle (see Figure 6). For example, under certain geophysical processes, a metamorphic rock can be formed from a sedimentary and/or igneous rock. Likewise, all rocks can become every other type of rock given the right circumstances. The rock cycle describes the processes that allow the creation of new rocks from old rocks. Use boxes or circles to show the different stages of rocks. Use arrows to show the changes in your rocks. ROCK SOLID Page 12 ROCK SOLID Post-Lesson Assessment 1. Of what material(s) is the earth's crust made? Give specific examples. (2 Points) ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 2. How do rocks break in nature? (2 Points) ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ 3. How would the breaking of a large rock affect people? (2 Points) ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ ROCK SOLID Page 13 ROCK SOLID Teacher Notes 1. Day 1 – Video, Rock Solid Part 1-4 and when completed book questions about erosion and weathering. 2. Day 2 – Part 5 – Soap lab 3. Day 3 and 4 – Rest of sections….Part 6 and post assessment ROCK SOLID Page 14