Name: Date: Class: Physical Weathering. As you go from station to station, please follow all directions as they are presented to you.

Transcription

1 Name: Date: Class: Weathering Stations Physical Weathering As you go from station to station, please follow all directions as they are presented to you. Station 1 Frost Wedging At this station you should examine the three pictures and try to determine what is going on. Why is the rock in the picture split the way it is? Please answer the following questions: 1. Explain frost wedging and how it weathers rock. 2. Explain why climate and topography can have an effect on the amount of weathering that takes place. 3. Why should you never leave soda in the freezer or in a car overnight when the temperature is below 32 o F?

2 Station 2 Abrasion At this station you will be examining the effects that abrasion has on rocks. In this activity, we will be substituting sugar cubes for rocks. Directions 1. Using the electronic balance, find the mass of 5 sugar cubes. 2. Place the 5 cubes into the shaker bottle and shake it vigorously 20 times. 3. Dump the contents of the bottle into a tray and separate the cubes from the crumbs. 4. Using the electronic balance, find the mass of the 5 cubes 5. Sketch one of the cubes in the space provided 6. Repeat steps 2-5, adding 20 shakes each time (use the data table below as a guide) 7. When you have finished with your 100 shake trial and have taken your final measurements please dump all of the sugar into the trash and leave the station exactly as you found it. Shaking Trial Drawing of Sugar Cube Mass of Sugar Cubes (g) 0 Shakes 20 Shakes 40 Shakes 60 Shakes 80 Shakes 100 Shakes

3 Please answer the following questions: 1. Describe the overall trend for what is happening to the shape and mass of the cubes. 2. How do you account for the changes to the cubes? 3. Where in nature do you think you would see something like this? 4. If we assume that the sugar cubes represent rocks, what does the powder/crumbs that remain after shaking represent? Why?

4 Station 3 Organic Weathering At this station please read the following documents and look at the images that are provided, and then answer the questions that follow. You may read silently to yourself or to your partner but if you choose to read out loud, please be courteous of your classmates who may be reading quietly around you. 1. In Earth Science: The Physical Setting, please read the organic activity section (p. 345) and the human activity and plant and animal activities sections (p. 352) 2. Page with images 3. Article on gophers Please answer the following question: 1. List 4 ways that human or animals can affect the weathering of materials a. b. c. d. 2. Explain how plant activities weather rocks or soil.

5 Chemical Weathering Station 1 Oxidation At this station you will examine the effects of exposure to the air. Take a look at the objects in front of you. Think about what has changed from their original form to what you see now. Read this passage from Earth Science: The Physical Setting: Oxidation The process by which elements combine with oxygen is called oxidation. Oxidation commonly occurs in rock that has iron-bearing minerals, such as hematite and magnetite. Iron, Fe, in rocks and soil combines quickly with oxygen, O 2, that is dissolved in water to form rust, or iron oxide, Fe 2 O 3 : 4Fe + 3O 2 2Fe 2 O 3. The red color of much of the soil in the southeastern United States is due to mainly the presence of iron oxide produced by oxidation. Similarly, the color of many red-colored rocks is caused by oxidized, iron-rich minerals. Please answer the following questions: 1. What do you think can be done to prevent or slow oxidation? 2. In what situations have you seen oxidation?

6 Station 2 Organic Acids At this station you will examine the chemical effects that organics can have on objects. Please read the NYT article and answer the associated questions. You may read silently to yourself or to your partner but if you choose to read out loud, please be courteous of your classmates who may be reading quietly around you. Please answer the following questions: 1. How does organic chemical weathering differ from organic physical weathering? 2. How do you think these historical treasures can be preserved?

7 Station 3 Acid Precipitation At this station we will examine the effects of acid precipitation on rocks and manmade structures. For our purposes, we will be substituting pieces of chalk for rock and vinegar for acid rain. Chalk is made of calcium carbonate, CaCO 3, while vinegar contains acetic acid which is a weak acid that can have an effect on carbonates. From Earth Science: The Physical Setting Natural rainwater is slightly acidic because it combines with small amounts of carbon dioxide. But when fossil fuels, especially coal, are burned, nitrogen oxides and sulfur dioxides are released into the air. These compounds combine with water in the atmosphere to produce nitric acid, nitrous acid, or sulfuric acid. When these acids fall to Earth, they are called acid precipitation. Acid precipitation weathers some rock faster than ordinary precipitation does. In fact, many historical monuments and sculptures have been damaged by acid precipitation. Directions: 1. Take a piece of chalk and put it in the tray. 2. Use the dropper to spray the chalk with vinegar 3. Observe and record your observations to the right. 4. Try different amounts of vinegar and different angles to see if that changes what happens Please answer the following question: Why are marble sculptures so susceptible to chemical weathering due to acid rain?