4. What is “cohesion” as applied to a slope?5. What would permit sand grains to stand at a steeper slope? What would make a pile of sand grains collapse to be almost flat?7. What types of surfaces are most prone to sliding? What is the difference between a slump and a translational slide?15. What is in water in the ground that helps it dissolve limestone? Where does that substance come from?18. Name three of the eight states with the largest areas of ground subsidence, including sinkholes.20. Venice, Italy, is noted for numerous canals instead of normal streets that cars drive on. Why doesn’t it have many normal streets? Explain briefly and to the point. (Case in Poing: Subsidence Due to Groundwater Extraction).Name: _______________________Learning Unit 9: Mass Wasting and Subsidence Review QuestionsThis assignment is designed to assess your understanding of Unit 9 and includes some of the Questions for Review at the end of Chapters 8 and 9 from your text plus a few ad-ditional questions. Each question can be answered in one to two sentences. Please limit yourself to a maximum of three sentences. Access the assignment, complete it with ANSWERS IN A DIFFERENT COLOR FONT as a separate file, and send it back for evaluation and grading through the assignment tab by or before the due date. 1. What parts of the United States are most susceptible to landslides? In the United States, the most severe in states with hilly or mountainous terrain,which are mainly in the mid west, west, and eastern regions of the UnitedStates2. Why do people build in landslide-prone areas?People try to build in landslide prone areas because they think that if they build preventatives then they will not be effected by landslides. There are building codes that limit the steepness of slopes and the types of fill used in construction.3. Why is the friction force on a gently sloping slip surface greater thanthat on a steeply sloping slip surface?The reason for the friction force being greater on a gently sloping surface is because a bigger amount of the landslide is pressing against the slip surface while moving down the gentle slope.4. What is “cohesion” as applied to a slope? Cohesion is an example of Forces that resist movement down the slope are grouped under the term shear strength5. What would permit sand grains to stand at a steeper slope? Whatwould make a pile of sand grains collapse to be almost flat?In order for the sand grains to stand at a steeper slope, the stability of the soil or land would have to have been compromised after the last landslide. In orderfor the sand grains to fall flat, the land would have needed to suddenly settle, insomething such as a sinkhole. 6. What can you use to recognize the action of soil creep?A person can look at bent trees, tilted fences, poles, cracks in walls, doors andwindows stick7. What types of surfaces are most prone to sliding? What is the differ-ence between a slump and a translational slide?Steep surfaces are most prone to sliding. Surfaces that have loose or weak rocks or soil are also more prone to having slides. Slumps happen along a curving, concave-up surface of failure, often spoon-like in shape, while transitional slides happen most often on a relatively flat sloping surface of failure.8. List the main factors that affect whether a slope will fail (driving forcesof mass wasting).The main factors that affect whether a slope will fail are an 1) increase in the slope’s steepness, 2) a reduction of slope strength, usually because of weather-ing, burrowing animals, or infiltration of water 3) Water saturation, when heavy rain, rapid snowmelt, leaking water or sewage lines, or poor drainage happens in a short time, 4) an increase in weight at top of a slope 5) the removal of sup-port at the base of a slope and 6) shaking by either natural processes, such as an earthquake, or by human cause, such as an explosion or heavy traffic. 9. List three ways in which human activity can increase the danger ofmass wasting:Humans can increase the risks of mass wasting by overbuilding and depleting the nutrients in the land and causing the soil to become unstable, conducting explosions, or it can be caused by heavy traffic.10. List several distinctly different ways in which water can be removedfrom a wet slope that has slide potential.Some possible ways that water can be removed from a wet slope are by planting trees, or other kinds of vegetation, drainage ditches can be set up to run down the slope the water can be drained out, hydrauger holes can be drilledinto the ground and then lined with perforated pipe, so the excess water can then leak out. 11. What three methods can be used to minimize damage from rock-falls?1)Rock bolts, used to reinforce slopes consisting of cracked and fractured rock can be inserted, 2) a deflection wall can be built, to divert and funnel debris flows around structures and 3) a Shotcrete, a layer of concrete is sprayed out of a pressurized gun to cover a slope can be built12. What can be done to stabilize a steep, high, dangerous rock cliff orroadcut to keep it from collapsing onto a highway or railroad track?Inserting rock bolts are a great way to stabilize steep cliffs and protect the roadsand highways underneath from falling debris. The bolt is a retaining device usedto reinforce slopes consisting of cracked and fractured rock. They can be usedto reinforce cliffs, overhangs, and tunnels. Bolts that are anchored in concreteare particularly strong13. The disastrous Vaiont landslide in Italy involved what combinationof circumstances? (Case in Point: A Coherent Translational Slide Trig-gered by Filling a Reservoir)The two most common circumstances are when the land starts dipping in planesof weakness toward an open space. These planes might be sedimentary bed-ding planes, faults, or fractures in the rock. 14. What causes caverns in limestone—that is, where does the lime-stone go and why? The cavers in limestone is caused by groundwater, which is slightly acidic, the caverns are called karst terrain 15. What is in water in the ground that helps it dissolve limestone? Where does that substance come from?The water in the ground contains acid, which is what helps to dissolve the limestone. That acid comes from rocks and other sediments in the earth16. What causes sinkhole collapse—that is, where is the cavity that it collapses into and how does that cavity form? Sinkholes are
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