* Construction of a heavy building above a cavity loads it and can cause collapse. What material causes swelling soils? * smectite, the swelling clay What parts of United States and Canada are most susceptible to damage from swelling soils? * The Great Plains, east of the Rockies, the Gulf Coast states of Texas, Louisiana, and Mississippi, the Coast Ranges of California, some valleys of the Rocky Mountain states. How can you recognize the presence of swelling soils? * They are extremely slippery when wet. * The form a popcorn-like surface when dried out. What is bad about swelling soils? * Swelling deforms and cracks foundations, chimneys, walls, driveways, and roads. * Roads are extremely slippery when wet. * Landslides are more common. A cavity in what kind of material suddenly collapses to form a sinkhole? * sandy to clay-rich soil 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 air combining with rainwater. Name three of the eight states with the largest areas of ground subsidence, including sinkholes. * Florida, Georgia, Texas, New Mexico, Kentucky, Tennessee, Virginia, Missouri What are two main mechanisms of ground subsidence? * sinkholes, extraction of water or other fluids from sediments, and drainage of peat or other organic soils. How would you recognize a karst landscape? * a ragged “dissolved” limestone surface. 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. * extraction of groundwater under the city caused subsidence and sinking of the city below sea level. What specific area of the western United States is noted for almost 8 meters of subsidence in the past 100 years? Specifically what caused the subsidence? * The San Joaquin Valley (Great Valley of California). Subsidence caused by extraction of groundwater for agriculture.
What is the origin of all the lakes and springs in western Florida? * limestone caverns and sinkholes filled with water because of the high water table. Chapter 9 - Multiple choice questions: What causes sinkhole collapse; where is the cavity that it collapses into and how does that cavity form? A limestone cavern dissolves out with acid rain; a sinkhole forms when its roof collapses. * Soil above a limestone cavern percolates down into the cavern, leaving a soil cavity above; that cavity may collapse to form a sinkhole. An underground erodes a wide area; a sinkhole forms if its roof collapses The roof of a gold or copper mine collapses to form a sinkhole. Families of moles or gophers dig large underground chambers that can collapse to form sinkholes. What causes caverns in limestone? Hard grains of quartz sand carried in underground streams erode the soft limestone. They form when above collapse into the limestone Limestone readily dissolves in seawater so the caverns formed originally at sea level Groundwater in limestone is somewhat caustic so over many years it dissolves limestone.. * Rainwater dissolves carbon dioxide to make weak carbonic acid that dissolves limestone. Where in the North America are sinkholes most prevalent and why? In Michigan because outcrops of limestone are widespread and it is surrounded by the Great Lakes. In Washington State because of all the rain west of the Cascades In metamorphic rocks of the Canadian Shield because of all the lakes * In Florida because it is almost all limestone and has abundant groundwater In Colorado because layers of sedimentary rocks under the Great Plains bend up to the surface there.. What is karst and how does it form? * Karst is the ragged surface dissolved on the surface of limestone bedrock formerly buried under soil. Karst is windblown dust deposited in areas of dune-like hills. Karst is the deposit of calcium carbonate that precipitates on rocks in soil when groundwater evaporates. Karst is the cold wind that blows off the North Atlantic Ocean at times in late Fall.