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55 Cards in this Set
- Front
- Back
Types of motion (mass wasting)
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-falling
-flowing -sliding |
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Mass wasting
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the downslope movement of Earth's materials due to gravity
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Factors that cause mass wasting
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-rainfall
-construction -undercutting by waves -type of material that makes up ground -angle of repose |
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Which process of mass wasting causes most economic damage?
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surface creep
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slump
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when Earth's materials move along a curved surface
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Processes of Mass wasting
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-rock fall
-rock avalanche -landslide -slump -earthflow -mudflow -surface creep -solifluction |
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Which processes of mass wasting cause the most damage?
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surface creep and solifluction
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Human activities that enhance mass wasting
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-increased runoff leads to slumping in river bends
-building roads, retaining walls -lawn (watering, spectic tanks) -vegetation (limits how hard water falls, roots hold soil in place, slows runoff process, helps soil process) -unnatural drainage -urban areas |
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What does running water do?
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-erode
-sculpt the land -build up landscapes |
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angle of repose
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steepest angle at which material remains stable
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rockslides
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when blocks of bedrock break loose and slide down a slope
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debris slide
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when involved material is largly unconsolidated
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Where do earthflows form?
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on hillsides in humid areas
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Creep
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involves gradual downhill movement of soil and regolith
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solifluction
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when soil is saturated with water and the soggy mass flows downslope
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Permafrost
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permanently frozen ground that occurs in association with Earth's harsh tundra
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Sheet flow
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broad, thin sheets across the ground
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runoff
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when the rate of rainfall is greater than the land's ability to absorb it, additional water flows over the surface into lakes and streams
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discharge
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total amount of water flowing past a certain point (Q= width x depth x velocity)
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erosion
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lifting of particles by turbulant flow
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stream capacity
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total amount of sediment
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stream competence
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maximum sized sediment in a stream
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What is the most common destructive geologic hazard?
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FLOODS!!!
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What causes flooding?
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-more rainfall, snow melt
-natural part of the process |
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How often do rivers flood?
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About every two and a half years
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Where are flash floods most common?
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In deserts
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How does urbanization affect rivers?
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1. decrease in lagtime
2. decreases infiltration 3.increases runnoff 4. reduces vegetation |
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Flood Control measures
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- construct dams
-levees -dikes -straighten channels - fill in wetlands -riprap |
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laminar flow
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water particles move steadily downstream without mixing
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Turbulant Flow
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water moves in erratic fashion, swirling
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Factors in the Velocity of a river
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-gradient
-shape, size, and roughness -discharge |
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Gradient
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slope of stream
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longitudinal Profile
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cross section view of a river
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base level
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downward limit to stream erosion
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graded stream
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correct slope etc. necessary to maintain just velocity
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Oxbow Lake
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A curved lake produced when a stream cuts off a meander.
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Point Bar
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A crescent-shaped accumulation of sand and gravel deposited on the inside of a meander.
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Cut Bank
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the area of active erosion on the outside of a meander
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levees
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a dam along the river to force water into a channel (can be natural or artificial)
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Three Ways Streams Transport Things
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1. solution
2. suspension 3.bedload (bottom of channel) |
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Settling Velocity
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speed at which a particle falls through a still liquid
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Mouth
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point downstream where it empties into another body of water
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bars
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coarser components of a stream's laod
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meanders
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when streams form in a series of bends
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floodplain
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part of a valley that is inundated during a flood
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Alluvial Fan
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forms when a high gradient stream leaves a narrow valley in a mountinous terrian and comes out suddnely onto a broad blat plain
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Delta
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forms when a stream enters a lake or an ocean
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distributaries
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smaller channels it is divided into
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What are some sources of pollution?
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runoff
salts |
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Dams
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-try to limit flooding
-source of hydtroelectric power -affects the eco system -organisms need annual rise in water |
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causes for pollution in sreams (urban areas)
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1. excess sediment runoff
2. road runoff 3. trash, garbage from storm sewers 4. lawn chemicals 5. pathogens 6. agricultural runoff 7. stream pollution |
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Sustainable Remedies For Flood Management
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- better floodplain management
-space for natural wetlands -land use planning -building restrictions |
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Remedies For Pollution
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-restrictions on use of yard chemicals
-restrictions on use and application of agricultural chemicals -pet waste |
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Thalwag
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region of maximal flow velocity
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riprap
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-rock or other material used to stabalize the shore
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