PHSC 210 WEEK 5 Mastering Geology Assignments 7+ Mastering Geology Assignments 7 Item 1 Part A Where are the headwaters of the Mississippi River? Missouri River Rocky Mountains Gulf of Mexico Northern Minnesota Appalachian Mountains Part B Water erodes the outside of a river bend to form a __________. oxbow lake meander cut bank point bar drainage basin Part C What is discharge a measurement of? the amount of water flowing in a river the speed of a river the turbulence of a river the steepness of a river the ability of a river to erode Part D How did the Mississippi River delta form? Dams and locks trap sediment. To keep the Mississippi River clear for navigation, sediment is dredged and dumped along the shoreline and forms a delta. As sea level has risen since the end of the last Ice Age, wave action along the Gulf Coast has eroded the mainland, leaving behind a lobe-shaped landmass. As the Mississippi River enters the Gulf of Mexico, its velocity decreases and it begins to drop its sediment load. After Pangea broke apart, the North American plate has continued on a northward course, leaving debris on the trailing edge. When the Mississippi River floods its banks, sand grains settle out just beyond the river’s normal banks to form a natural ridge. Part E What has caused the hypoxic “dead zone” to form off the coast of the Gulf states? Poor farming practices increase the sediment load in the Mississippi River, blocking sunlight and thereby inhibiting photosynthesis. The highly turbulent Mississippi River carries so much sand and silt into the Gulf of Mexico during the spring that it chokes marine species. Fertilizers promote the growth of algae. When they die and decompose, oxygen is depleted in the Gulf of Mexico. Fertilizers flushed from farmers’ fields enter the river and promote algae growth, which then competes for oxygen with native fish and other marine species. Fertilizers and pesticides are toxic chemicals. When they run off of fields and into the Mississippi River, they make their way to the Gulf and poison fish and other species. Item 2 Gravity is the major controlling force of mass wasting. Mass movement occurs if gravitational force is greater than the resisting strength of a rock. The resisting strength is the sum of the frictional resistance to movement and the cohesion between minerals in the rock. The size of the gravitational strength is greater on steep slopes. Several processes can change the slope, friction or cohesion of a mass of rock or sediments and cause the slope to be unstable. The instability can trigger mass movement. The triggers include water saturation, vegetation cover, oversteepening slopes, and vibrations from earthquakes. The different types of mass wasting have their own unique characteristics in terms of material constituents, angle of movement and rate of movement. Hence, triggers for each mass wasting type are somewhat different. Part A – Triggers of Mass Movement In this activity, you will explore and test your knowledge about triggers of four mass movement types. Drag the appropriate labels to their respective targets. Item 3 Part A Which of the following are classifications describing how rock and other material move downslope? fall, creep, flow, slip, avalanche slide, avalanche, flow, waste, roll slide, creep, roll, flow, slump fall, slide, slump, creep, flow creep, flow, slip, waste, fall Part B What is mass movement? movement of material under the influence of gravity and wind movement of material under the influence of gravity and water movement of material under the influence of gravity alone movement of material under the influence of gravity and ice Part C How is a fall different from creep? Falls occur slowly and in areas with low slope, whereas creep occurs rapidly in areas with high slope. Falls occur rapidly and in areas with high slope, whereas creep occurs slowly in areas with low slope. Falls occur slowly and in areas with high slope, whereas creep occurs rapidly in areas with low slope. Falls occur rapidly and in areas with low slope, whereas creep occurs slowly in areas with high slope. Part D How are slumps and slides related? Slides are a type of slump in the special case where the rupture surface is linear. Slides are a type of slump in the special case where the rupture surface is curved. Slumps are a type of slide in the special case where the rupture surface is curved. Slumps are a type of slide in the special case where the rupture surface is linear. Part E How are debris avalanches and flows related? Debris avalanches are small, slow flows of rock. Debris avalanches are large, rapid flows of rock. Debris avalanches are large, slow flows of rock. Debris avalanches are small, rapid flows of rock. Part F Which type of mass movement event requires the addition of water? fall slump flow creep slide Part A Pre-existing rocks are broken down into smaller particles by which of the following processes? CHOOSE ALL THAT APPLY. oxidation unloading frost wedging thermal expansion lithification Part B In temperate and polar regions, the accumulation of talus slopes at the base of steep, rocky cliffs is most often attributed to which of the following processes? unloading or exfoliation biological activity oxidation frost wedging thermal expansion Part C The production of tabular slabs of rocks caused by unloading of material overlying igneous bodies is known as _____. sheeting talus exfoliation domes mining frost wedging Part D In the accumulation of particles in a talus slope, which of the following influences moves particles to their resting place? gravity glaciers running water wind sheeting Part E Mechanical weathering is a significant factor in the breakdown of rocks. Which of the following factors enhances the effectiveness of further weathering as particles are created? volume of rock increases increased surface area of the particles volume of rock decreases decrease in surface area rate of dissolution increases Item 5 Part A The chemical weathering process known as oxidation would be most effective in the breakdown of which of the following Earth materials? pyroxenes quartz calcite halite feldspars Part B The chemical weathering process known as dissolution is most effective in the breakdown of which of the following minerals? pyroxenes quartz feldspars olivine calcite Part C During hydrolysis, ions and clay minerals are produced by the decomposition of which of the following Earth materials? halite quartz feldspars calcite olivine Part D The Hawaiian Islands contain active volcanoes and are known for nutrient-rich soils and lush vegetation. What is the most powerful explanation for this? Minerals in the volcanic rocks produce clay minerals as weathering by-products. There is abundant rainfall. Volcanic rocks contain minerals rich in iron, so they are susceptible to oxidation. Volcanic rocks contain minerals susceptible to hydrolysis. all of the above Part E Sand dunes are typically dominated by quartz grains and very little other mineral matter. Why does this selection occur? Quartz is only susceptible to hydrolysis. Quartz is extremely resistant to all forms of chemical weathering. Quartz is only susceptible to oxidation. Other minerals are removed by the wind because they have a lower density. Quartz is only susceptible to dissolution.