Geology 101. Reading Guides for Chapters 5 and 14 Weathering: the Breakdown of Rocks (p. 142)

Transcription

1 Geology 101 Name Reading Guides for Chapters 5 and 14 Weathering: the Breakdown of Rocks (p. 142) Please read the introduction to the chapter. What is the difference between weathering and erosion? Weathering Processes (p. 144) Mechanical Weathering: (p. 144) What is the difference between mechanical and chemical weathering? What are some ways in which mechanical weathering occurs? Chemical Weathering: (p. 147) For those who have had a chemistry course, you may be able to follow the chemical formulas in this section, but since most of the students in this class have not had a previous chemistry course, I will not expect you to know these formulas or be able to use them. If you have questions or would like to know more about them, see me during an office hour. List and briefly explain the three primary chemical weathering processes: 1) 2) 3)

2 Factors that Influence Chemical Weathering: (p. 152) What role does climate have in promoting chemical weathering? What type of climate does chemical weathering occurs at the fastest rate? Slowest rate? In general, rocks with more mafic minerals (dark colored) will chemically weather (faster/slower) than more felsic minerals. We can explain this trend because mafic minerals formed at higher temperatures, so they are the (least/most) stable at the earth s surface. Some Products of Chemical Weathering: (p. 155) From the previous section you learned that hydrolysis produces clays. These clays are useful in our world as are the metallic ores concentrated as a result of the weathering processes, but I will not ask the details of this material on an exam. You should be familiar with spheroidal weathering and how it forms. You see this in some of the basalts in eastern Washington. Weathering occurs faster on the corners and edges of the basalt columns, creating rounded masses of basalt without tumbling in a river. Soils and Soils Formation (p. 156) Influences on Soil Formation: (p. 157) An important idea in this section is that soils are also a function of the rock type of the bedrock. Soils that are derived from sandstones will be much sandier than soils derived from shales that will be more clayey. Sections entitled Typical Soil Profile, Classifying Soils, and Weathering in Extraterrestrial Environments will not be covered on the second exam. Students in Forestry and Civil Engineering may want to read the soils information carefully for applications in their field. 2

3 What Causes Mass Movement? (p. 438) Gravity, Friction and Slope (p. 438) Reading Guide for Chapter 14: Mass Movement (p.436) promotes down slope movement; resists it. What are some ways that the friction between a rock (or mass) and a hill can be reduced? What are some natural and human reasons that slopes are increased in angle? Slope Composition (p. 438) Solid Bedrock the six characteristics/conditions help us explain why solid rock sometimes fails. I will not ask you to list these six items, but you may need to be able to apply them to situations. I recommend reading them carefully, but you do not need to memorize them. One of the important ideas in this section is that layered rocks (such as layers of sedimentary or metamorphic rocks) may become folded (tilted) and the bedding planes between these layers are weak and frequently are the source of instability in a hillslope. The angle of repose concept only applies to materials. The angle of these materials depends primarily on their and their. Other than reducing the frictional forces in materials, what role does water play in the stability of a hillslope? 3

4 Setting Off a Mass-Movement Event (p. 441) The text divides the triggers of landslides into natural and human-induced triggers. What are some common characteristics of both natural and human-induced triggers? Types of Mass Movement (p. 444) Slow Mass Movement (p. 444) and Rapid Mass Movement (p. 444) Matching: Answers may be used more than once. 1. A mass movement that rotates as a block along a concave slip plane. Usually occurs in cohesive materials. 2. Relatively dry mass movements. They ooze downslope with a relatively high viscosity 3. The Gros Ventre mass movement is an example. 4. When news announcers say a mudslide has occurred, it is most likely this type. 5. A very slow type of mass movement that affects slopes at most latitudes. Freezing and thawing is one way this process occurs. 6. The fastest type of mass movement occurs when loose sediment or rocks breaks free 7. This type of mss movement moves along a defined slip plane. Normally parts of the mass hold together. 8. Common in semi-arid regions. Similar to mudflows but particles are larger. A. creep B. solifluction C. rock slide D. slump E. debris flow F. earthflow G. fall H. slide What are some characteristics of slumps? What is the difference between an earth flow and a debris flow? Avoiding and Preventing Mass-Movement Disasters (p. 454) 4

5 List four specific characteristics that we could use to determine a slope is unstable? (use the diagram on page 460) List three ways in which humans can reduce the risk associated with mass movements? Extraterrestrial Mass Movements (p. 459) You may read this section if you are interested, but you will not be tested over this material. 5