Western California and Oregon (or Coast Ranges of), western Colorado, Appalachians (or western Carolinas and Virginia, West Virginia, Pennsylvania)A larger proportion of the load is pressing against the slip surface on a gentle slope.4. What is “cohesion” as applied to a slope?The holding together of otherwise loose grains on a slope – generally by moisture or cement.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?A little moisture permits sand grains to stand at a steeper slope (like building a sand castle). Too much water – enough to fill all of the pore spaces between the grains - would make a pile of sand grains collapse (too much water destroys a sand castle).7. What types of surfaces are most prone to sliding? What is the difference between a slump and a translational slide?Bedding planes between layers of sedimentary rock dipping towards an open space.Slopes undercut by erosion at their base.Old landslides slip surfaces.Control of surface water flow on vulnerable slopes can be done by planting vegetation (increase evapotranspiration), and/or by drainage ditches set at regular intervals on the slope to permit external drainage.rockboltscoating with shotcretedraping with heavy wire mesh15. What is in water in the ground that helps it dissolve limestone? Where does that substance come from?Carbonic acid; it forms from carbon dioxide in the air combining with rainwater18. Name three of the eight states with the largest areas of ground subsidence, including sinkholes.Florida, Georgia, Texas, New Mexico, Kentucky, Tennessee, Virginia, MissouriKarst is the ragged surface dissolved on the surface of limestone bedrock formerly buried under soil. Rainwater dissolves carbon dioxide to make weak carbonic acid. That acid seeps down into cracks in limestone, dissolving it and leaving high points or spines between the cracks.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).Extraction of groundwater under the city caused subsidence and sinking of the city below sea level.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 Ques-tions for Review at the end of Chapters 8 and 9 from your text plus a few additional questions. Eachquestion 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? Western California and Oregon (or Coast Ranges of), western Colorado, Appalachians (or western Carolinas and Virginia, West Virginia, Pennsylvania)2. Why do people build in landslide-prone areas?For the views, it is in a scenic area, boulders make for scenic landscaping.3. Why is the friction force on a gently sloping slip surface greater than that on a steeply sloping slip surface?A larger proportion of the load is pressing against the slip surface on a gentle slope.4. What is “cohesion” as applied to a slope? The holding together of otherwise loose grains on a slope – generally by moisture or cement.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?A little moisture permits sand grains to stand at a steeper slope (like building a sand castle). Too much water – enough to fill all of the pore spaces between thegrains - would make a pile of sand grains collapse (too much water destroys a sand castle).6. What can you use to recognize the action of soil creep?Tree trunks that bend out from a slope before curving up; fences or walls that tilt down slope, cracks in walls and foundations, sticking doors and windows.7. What types of surfaces are most prone to sliding? What is the difference be-tween a slump and a translational slide?- Bedding planes between layers of sedimentary rock dipping towards an openspace. - Slopes undercut by erosion at their base. - Old landslides slip surfaces.A slump fails as a relatively coherent rotational mass whereas a translational slide moves parallel to the surface of the slope.8. List the main factors that affect whether a slope will fail (driving forces of mass wasting).- Increase in slope steepness (shear force of gravity). - Reduction of slope strength by weathering, by burrowing animals, or by infiltration of water. - Water saturation. The single most important factor in most mass wasting. Water saturation can result from heavy rain, rapid snowmelt, leaking water or sewage lines, or poor drainage. Water saturation weakens rock by buildingup pore pressure and by lubricating contacts between particles. - Increase in weight at top of a slope. - Removal of support at the base of a slope. - Shaking by either natural processes (earthquakes) or human activities (ex-plosions, heavy traffic). 9. List three ways in which human activity can increase the danger of mass wast-ing:Adding water, loading the top of a slope, undercutting the slope, removing vegetation10. List several distinctly different ways in which water can be removed from a wet slope that has slide potential.- Water within the ground can be controlled by hydrauger holes: horizontal holes drilled into the ground and lined with perforated pipe. Excess water leaks into the pipes and flows into other pipes that take it away from the slope. An example is shown in this photograph. - Control of surface water flow on vulnerable slopes can be done by planting vegetation (increase evapotranspiration), and/or by drainage ditches set at regular intervals on the slope to permit external drainage. 11. What three methods can be used to minimize damage from rockfalls?- rockbolts- coating with shotcrete- draping with heavy wire mesh12. What can be done to stabilize a steep, high, dangerous rock cliff or roadcut to keep it from collapsing onto a highway or railroad track?See question 11.13. The disastrous Vaiont landslide in Italy involved what combination of circum-stances? (Case in Point: A Coherent Translational Slide Triggered by
View Full Document
Unlocking...