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This 9 page Study Guide was uploaded by Alanna Wight on Monday November 16, 2015. The Study Guide belongs to Geology 101 at Washington State University taught by Wilkie in Fall 2015. Since its upload, it has received 120 views. For similar materials see Geology in Geology at Washington State University.
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Date Created: 11/16/15
Geology 101 Quiz 3 Study Guide Alanna Wight Chapter 13 – Unsafe Ground: Landslides and Other Mass Movements Know the controlling force of mass wasting – GRAVITY The processes that transport large quantities of earth materials down slope Know the important factors in mass wasting (water saturation, angle of repose, vegetation, earthquakes) Nature of Slope Material: o Solid rock may be reduced by deformation, physical, chemical weathering o Sedimentary rocks with bedding planes o Foliated metamorphic rocks Unconsolidated Material Angle of repose maximum angle at which a slope of loose material will lie without cascading down o Shape and size of grains, amount of friction and cohesion affect Vegetation plants add slope stability by protection against erosion Water Saturation water fills pore spaces o Water in some spaces binds particles o Water between all particles keeps them apart and allows them to flow o You WANT damp sand! Not dry or watersaturated Steepness affected by tectonic and erosion activity, human interactions Review the types (fall, slide, flow) and rates of movement (e.g., creep compared to rock avalanche) Fall solid blocks of rock fall rapidly from a steep or vertical slop, ONE UNIT FAST ROCK o Talus is debris Rock Avalanche flows by entraining air as it moves down slope, FLUID FAST ROCK o Air hockey table Slide single mass of rock or sediment is released and moves rapidly along a plane of weakness, ONE UNIT MODERATE ROCK Creep slowest mass wasting process, unconsolidated material moves slowly downslope under the influence of gravity, FLUID VERY SLOW UNCONSOLIDATED o Causes once vertical objects to slant over time Slump rapid slide of unconsolidated material (usually soil) along a curved surface, ONE UNIT SLOW TO MODERATE UNCONSOLIDATED o Travels as a unit, typical of the Palouse o Typically forms stepped scars Flows fluid mass movement high water content o Debris avalanche is fastest, mixed with air Know the effects of deforestation on mass wasting deforestation alters the rates at which natural erosion and deposition take place How do structures in the rocks affect mass wasting? Nature of Slope Material: o Solid rock may be reduced by deformation, physical, chemical weathering o Sedimentary rocks with bedding planes o Foliated metamorphic rocks What are the triggers for mass wasting? Can human activity trigger mass wasting? How? Weathering, Physical erosion, Faults/Folds (tectonic activity) Human Activity: added mass of building on slopes, removal of vegetation, increasing angle of slopes, addition/removal of water Chapter 14 – Running Water: The Geology of Steams and Floods How do rivers and streams fit into the hydrologic cycle (run off verses infiltration)? run off is when water returns to the sea infiltration makes weak surfaces underground more slippery Not all runoff flows into rivers, much of it soaks into the ground as infiltration What are the different water reservoirs? Be able to place them in order from largest to smallest? ocean glacier groundwater How are materials transported in rivers and streams? What are the sediments called that are transported via streams? Dissolved load in solution (ions) Suspended load in suspension (finer particles that are suspended in water column, murky muddy) Bed load along the bottom (large particles, sliding rolling saltation (bouncing)) o Movement of bed load forms ripple marks at LOW velocity o Movement of bed load forms dunes at HIGHER velocity Be able to recognize the difference between stream channel types (straight, meandering, braided). Straight fast flowing, mountain streams (steep slopes), straight segments Braided multiple channels, split and rejoin, carries high amounts of sediment, high velocity at terminus of glacier Meandering one main trunk winds back and forth across flood plain, low slopes (low velocity) through easily eroded bedrock (low suspended sediment) Be able to recognize the different stream drainage patterns and what each tells you about the underlying rocks. (dendritic – flat lying or composed of similar materials, etc.) Drainage basin area of land which funnels all the water into streams draining the area Drainage divide ridge of high ground along which all rainfall runs off down one side of the rise or the other Dendritic flat lying layers (similar rock type) o Looks like tree Trellis folded rock layers o Rectangular rock units cut by joints or faults o Radial high mountain peal (volcanoes) o Point with streams coming off it (like a flower or sun) Describe how velocity changes within a meandering stream. How does this lead to the formation of point bars and cut banks? How do meandering streams change over time? How do oxbow lakes form? Velocity is higher in the middle of the stream, in a meandering stream the high velocity area bumps against the points of the stream causing high erosion. Cut banks form in the inside bends where the velocity is slower, depositing materials. Meandering streams change as erosion increases, cutting bigger bends. In floods, new streams can form connecting bends, and cutting off the larger bends to become oxbow lakes, IF two bends are close by they will connect Be able to define (and recognize units of) the following terms: velocity, gradient, discharge. Velocity speed of the stream Distance over Time Gradient rise over run (slope) Feet per mile Discharge the volume of water flowing past a certain point in a given unit of time (typically cubic feet per second or CFS) Q=VxA in terms of CFS 25ft/16.3seconds= 1.53 ft/sec 35ft x 1.53ft/sec= 50.49 ft squared 50.49ftsq x 1.53ft/sec= 77.25 ftcubed/sec = 72 CFS Recognize and explain how the following form: floodplain, levees, terraces, alluvial fans, deltas. Floodplain area covered in water during flooding, fine sediments are deposited at the outer parts of the floodplain Levees—during a flood the thickest and coarsest sediments are deposited at the channel edges o ManMade: increase sediment deposition (raising channel above floodplain) increase time to drain flooded areas behind levees backs up water upstream of levee, increasing flooding in upstream areas Terraces—mark previous level of floodplain, formed by renewed down cutting to lower base Alluvial Fans—fan shaped accumulations of sediment o Form where streams adjust velocity when leaving a narrow valley for a broad relatively flat area o Bajada multiple alluvial fans that have merged Deltas—triangular shaped deposits of sediment deposited as streams enter the ocean (slow velocity) If a flood has a recurrence interval of 20 years, what is the % chance that this magnitude flood will happen this year? What about the next year? Recurrence interval the average time between two floods of a given magnitude o Depends on climate, width of floodplain, channel size 5% it will happen this year, 5% next year Chapter 16 – Hidden Reserve: Groundwater Be able to describe the hydrologic cycle. Water enters the hydrologic cycle by evaporating from the earth's surface and rising into the atmosphere. After a period of time, this water condenses and falls back down in the form of rain or snow. Some of this rain or snow stays on the land and surface water. Gravity then plays its part in making all the surface water run down the slope. This running water collects in stream sources and are moved from the higher to lower elevation. List the factors that control the rate of groundwater recharge (infiltration). 1) Condition and type of surface materials 2)Vegetation 3)Topography 4)Precipitation Be able to use the following terms as related to lecture and lab: unsaturated zone, saturated zone, water table, porosity, permeability, aquifer, confined aquifer, aquiclude, artesian well, and recharge. Unsaturated zone and Saturated zone: how far you dig until you reach water. Water table: boundary between unsaturated and saturated zone. It is not constant. Porosity: total volume of pore space in a sediment or rock. Permeability: The ability of water to flow through spaces in rock. Aquifer: the space between two aquitards, is not open to the surface. Unconfined Aquifer: open to the surface (saturated and unsaturated zones) with a water table. Aquitard: bed or rock through which water cannot move or move slowly. Artisian Well: Penetrates confined aquifers in which water is under enough pressure to rise above the surface on their own. Water flows freely without help. Recharge: When water enters or reenters the ground. Consider the following 6 rock/sediment samples. Which sample/samples have high or very high porosity? Which has the highest permeability? Which sample/samples would be most likely to form aquifers? Which sample/samples would form aquitards? Gravel High permeability high porosity Clay= low permeability low permeability. Porositytotal volume of pore space in sediment or rock High perm=lots of water Permeabilitythe ability of water to flow through spaces in rock and sediment Sample A wellsorted, coarsegrained unconsolidated sediments.(high) Sample B very poorly sorted unconsolidated sediments.(very high)(highest permeability) Sample C highly fractured basalt (very high) Sample D unfractured granite, with no vesicles (low) Sample E unfractured mudstone /shaleSample F very well cemented sandstone Explain when and why the following occur: cone of depression, subsidence, saltwater intrusion Cone of Depression: Occurs when water in pulled out of an aquifer faster than it can recharge. Subsidence: When large amounts of ground water have been excessively withdrawn from an aquifer Saltwater intrusion: The movement of saline water into fresh water aquifers. Can lead to contamination of drinking water sources. What is the difference between hot springs and geysers? What heats the water of hydrothermal activity? What is the source (plate boundary or hot spot) of heat for the geysers of Yellowstone? Yellowstone is known for both its hot springs and geysers. These are heated by a pluton beneath the north american plate. What is karst? How is it related to groundwater? In which rock type does karst most commonly form? Describe the features of karst (below and above the earth’s surface). Karst is a type of topography that indicates the presence of caves belowground. This is typefied by sinkhole, disappearing streams and hillside springs What is dissolution? Caves are formed primarily in limestone which dissolves in acid including the slightly acidic water that is naturally found in many groundwater reservoirs. What are speleothems? How do they form? Speleothems are made of which mineral? How does it form caves? How do stalactites differ from stalagmites? speleotherms features formed through water based deposits of CaCO3 stalactites and stalagmites are considered speleotherms stalactites top stalagmite bottom How do collapse sinkholes form? Sinkholes are formed when the overlying sediment weight becomes too much for the cave to support. This happens in three primary ways: the cave becomes too large and the ceiling too thin (can collapse), water subsidence removing the grain support, or increased weight at the surface. What are some possible sources for groundwater pollution that you may see in a rural or urban setting? Agricultural waste, industrial waste, effluent from "sanity" landfills and septic tanks, radioactive waste. Chapter 15 – Restless Realm: Oceans and Coasts How do we know what the seafloor is like? Explain how man has been able to map the seafloor we mapped it through a variety of ways early navigators used a lead line survey used LIDAR and bounce light off of the ocean bottom to get a more detailed picture best way is through satellite laser imagery. The ocean surface hints at what is under water and lasers can be used to measure the height of the ocean at different spots to within inches. Have portions of the continental shelf ever been exposed at the surface? If so, when might this occur and how might this change its surface? Does the continental shelf area have any economic importance? Please explain The continental shelf comes to the surface at convergent boundaries. It is found as blueschist evidenced as shells found at peaks of the himalayan mountains. During convergence the sea floor moves up as an accretionary wedge or as nonvolcanic mountains. The continental shelf is important economically because it is an area where metallic ores hydrocarbon and oil are very frequently removed. Identify the type of mass movement of sediment which occurs along the continental slope and rise. What submarine features do they give rise to? Dissected by submarine canyons and modified by turbidity currents How do waves form? What factors would increase a waves’ height? Understand and be able to explain the following terms: wavelength, wave height, and wave period. Waves form through wind. The stronger the wind, the higher and bigger the waves. Wavelength: The distance between crests Wave height: vertical distance between the crest and trough. Wave period: time between successive waves to pass Be familiar with the major parts of a beach profile. What is the swash zone? What causes breakers (breaking waves) in the surf zone? What is a long shore current? And how does it move sediment? Swash zone: zone where water comes on beach from a wave. Gravity causes breakers as the top of the wave gets too high. Longshore Current: where waves arrive at the shore obliquely. This moves sediment because it moves in a sawtooth pattern that results in gradual transport of the beach sediment parallel to the beach. A rip current is a seaward strong flow perpendicular to the beach. Explain what causes ocean tides on earth Ocean tides on earth are caused by the gravitational pull from the moon and sun. Tides are higher at some locations because they are closer to the sun/moon at certain times. Be able to identify some erosional coastal landforms (wave cut cliffs, platform, terrace, sea stacks, sea arch), and depositional coastal landforms (tombolos, sand spits, barrier islands). Also be able to identify emergent and submergent coastlines and what landforms occur there. Wave cut: when wave erosion gradually undercuts a cliff face. Sea stacks: because the refraction waves attack the sides of a headland, slowly eating through it creating a sea arch. Eventually this arch collapses leaving sea stacks. Tombolo: A depositional landstructure as an island that is connected by a narrow land bridge like a spit. Sand spits: the coastland idents landward, beach drift stretches beaches out into open open water to create a sand spit. Barrier Islands: in regions with an abundant sand supply offshore bars rise above the mean high water level and become barrier islands. How do seasonal changes affect beach profiles? Manmade structures like groins, breakwaters, jetties are used to prevent beach erosion. In general what is there affect where there constructed? And the affect downcurrent (down coast) of the structures? When humans add structures in order to slow erosion sediments typically become piled and downstream is quickly eroded away. When other approaches are taken (beach nourishment, land use planning) erosion is typically not caused in new areas.
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