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152 Cards in this Set
- Front
- Back
Cycle of Erosion
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W. M. Davis, youthful landscapes, peneplain, mature stage, downwearing
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Backwearing
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Walter Penck, pediment, inselberg, haldenhang
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Dynamic Equilibrium
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G. K. Gilbert, resistance, shear stress, equilibrium
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The waves beneath your cliff-side mansion have eroded the bottom of the cliff, increasing the slope angle.Which model of landscape evolution was developed to understand how to analyze such circumstances?
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Dynamic Equilibrium
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You go golfing. After a very bad round, you look across the flat plain made up of the hard rock type, granite. Behind the flat plain is a very steep isolated mountain, and there is a sharp slope angle at the mountain/plain junction. Which model of landscape evolution was developed to explain this pediment-inselberg landscape?
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Backwearing
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Falls, topples, and slides are examples of what?
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Mass wasting
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The key factor in all mass wasting events is ___________.
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Gravity
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Before a rock on a cliff can fall, what must happen first?
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Detachment from a steep slope or undercutting
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The pile of boulder rock falls that pile up at thebase of a cliff is called? When the rocks are smaller (cobbles), the pile is called? When the pile has a conical shape, it is called?
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Talus
Scree Talus Cone |
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When the rock fall is a rotating slab, it is called a _________.
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Topple
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Slides are ___________ when the failure occurs on a plat plane and ___________ when the failure occurs curved surface
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Translational
Rotational Slump |
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Your family won the lottery and is thinking of buying a condo at a ski resort. Like most ski resorts, avalanches are a concern. The real estate agent assures you that there's no danger. You look up at the mountain side and notice that the condo is underneath a gully with no trees. You tell the real estate agent that you won't buy here. What made you decide to avoid this spot?
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Your family won the lottery and is thinking of buying a condo at a ski resort. Like most ski resorts, avalanches are a concern. The real estate agent assures you that there's no danger. You look up at the mountain side and notice that the condo is underneath a gully with no trees. You tell the real estate agent that you won't buy here. What made you decide to avoid this spot?
A lack of trees indicates that the path is an avalanche chute, and avalanches thus frequently occur in this area. |
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What process turns solid material into a "plastic" that would flow downhill?
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Liquifaction
Thixotropic? |
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What is the difference between an earthflow, debris flow and mudflow?
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Earthflow: slow, deep, travel a few meters a day
Mudflow: fast, lots of mud, little rock content Debris flow: fast, lots of mud, lots of rock debris |
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Why do fires often lead to debris flows?
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Fires destroy the top layer of soil, resulting a lower root resistance to precipitation that then causes debris flow.
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A debris flow leaves ______, ridges along the side, as it flows.
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Levees
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What is sorting? How can sorting be used to distinguish a debris-flow deposit from a stream flood?
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Water or some other medium distributes sediment grain sizes, from small pieces to big pieces, in layers.
Water is good at sorting particles, and the layers are made of fairly similar sediment sizes. Debris-flow deposits carry an unsorted mixture of highly varied sediment sizes in which bigger pieces can "float" on top of smaller pieces. |
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What factors contribute to a mass wasting event? Could you pick out the wrong answer from a list of right answers? (odd-man out multiple choice question)
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Weak make-up of slopes (weathered rock, lots of clay)
Rock structure Steep slopes Pore pressure (rain raises the water table) Vegetation loss Removal of lateral support (undercutting from waves, streams, etc.) Added mass on slopes Transitory earth stresses (earthquakes, volcanoes, etc.) |
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Large landslides like Vaiont, Gros Ventre, and Madison River slides often have failure surfaces that have a layer of rock material (that slides) on top of a ________ tilted layer of ________.
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Downslope
Sediment |
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Permeable slopes
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transport-limited landscapes, vegetation covered, soil covered, creep is common,
convex slopes, tree-trow and other biogenic transport, stream channels uncommon |
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Impermeable slopes
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weathering-limited landscapes, desert/little vegetation, bare rocks common, overland flow of water, rills and gullies and stream channels are common, concave upward slopes
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What forces push a creeping soil particle away from the slope?
What force moves the particle down? |
Expansion from wetting or freezing
Gravity from drying or melting |
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Slope angle and lengths remain uniform as the slope retreats parallel to itself. Hillslopes are essentially free of sediment. ______ retreat occurs where underlying strata are protected by a resistant cap rock, such as a layer of sandstone, limestone, or lava. Failure of the caprock occurs only when erosion has removed the weaker rock supporting it.
-Penck's idea |
Parallel
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Upper slope weathers and erodes at at faster rate so there is progressive decline of slope angle occurs. Hillslopes have a thick mantle of regolith.
-W.M. Davis idea |
Slope decline
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Fences and old tomstones twisted and tilting downhill give you visual clues that what process is operating?
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Creep
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Why is the infiltration capacity of the slope so important?
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Infiltration capacity is the maximum amount of water that can enter the soil over a given time period.
It distinguishes permeable slopes from impermeable ones. Overland flow, and consequently the formation of rills and gullies, is based on infiltration capacity. |
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For overland flow to occur, what has to be greater: precipitation or infiltration rate? Why?
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The greater the precipitation, the greater the chance that the amount of water will exceed the infiltration rate and
cause overland flow. |
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Overland flow concentrates into ________.
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Rills
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What factors can turn rills into deep gullies?
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Slope too flat to concentrate flow
Rill erosion Gully erosion |
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This image is an example of a _____ limited landscape.
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Either weathering-limited (a desert) or transport-limited (a grassy field)
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The ____ of ____ is the stable ____ of earth material. If this is exceeded than downslope movement can occur.
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Angle of repose
Slope |
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A magnitude 7.0 earthquake
is ____ times larger than a magnitude 6.0 earthquake. |
Ten
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A _______ earthquake can generate _____ by displacing water over head.
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Submarine/underwater
Tsunamis |
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A magnitude ___ earthquake was the largest earthquake ever recorded. It took place in _____.
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9.5
Chile |
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The coasts of Japan, Chile, and the Pacific Northwest-USA, all have to worry about the potential of ______.
This is because each of these areas is located in close proximity to a _____ _____, which can lead to megathrust earthquakes. |
Tsunamis
Subduction zone |
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the oceans hold the most water. What are the next four biggest "reservoirs" of Earth's water, in order from most to least.
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Atmosphere
Glaciers Surface lakes/streams Groundwater |
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What type of water rises up against gravity? How can this cause salinization of soils?
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Capillary water
If plants extract capillary water from a salty water table, then salt can be transported to the soil surface and evaporate, thereby accumulating and causing salinization |
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How does water get into the ground?
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Gravity pulls water down through the soil
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What keeps water from getting into the ground?
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Soil texture, especially coarse-grained soils
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What would be a good example of an impermeable layer of rock?
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Bedrock
Aquiclude - shale compressed mud |
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What would be a good example of a layer of rock that is both permeable and porous?
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Shale
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Water moving downward towards the water table passes through what?
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Zone of Aeration/Vadose Zone
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The level of water in a well is the level of the?
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Water table
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Pumping water from an aquifer causes what to occur?
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The flow of groundwater
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When infiltrating water recharges ground water, what happens to the water table?
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Rises
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What is so special about an artesian well or spring?
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Artesian aquifers are confined by aquicludes, so the groundwater flows upward through the artesian well without having to be manually pumped
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Why does the removal of groundwater from an aquifer of unconsolidated sediment cause subsidence? What process happens?
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Drawdown causes the compaction of sediments because they are no longer supported
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What are different ways that groundwater can return to the surface?
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Baseflow to streams
Baseflow to marshes and lakes In springs |
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Explain the steps involved in how the oil or pesticide or some other contaminant dumped in the desert away from the city gets into your drinking water.
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Everything dumped in water gets mixed in the watershed, which can contaminate groundwater and therefore contaminate drinking water to
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How can groundwater supply water to a stream?
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Effluent streams are below the water table and are thus fed by groundwater/baseflow
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Under what circumstances does a stream supply water to groundwater?
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Influent streams are above the water table and thus supply the groundwater
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Influent streams:
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high drainage density, ephemeral stream flow, desert climates, little vegetation, less permeable slopes, more overland flow, weathering-limited landscapes, little soil cover
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Effluent streams:
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low drainage density, perennial stream flow, wet climates, abundant vegetation, permeable slopes, more infiltration, transport-limited landscapes, abundant soil cover
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What is plotted in a hydrograph?
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Discharge/Stage vs. Time
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How does a hydrograph of a desert stream differ from a hydrograph of a stream in a forest?
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For the same period of time, the discharge of a desert stream will be less than the discharge of a forest stream
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Tributary streams come together a funnel water through a single location in what geographic entity?
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Drainage basin
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What is a drainage divide? What is the continental divide?
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Line separating neighboring drainage basins
Line separating waters that flow to different oceans |
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Where would you expect to find the most erosion within a drainage basin? Where would you expect to find the most deposition within a drainage basin?
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Most erosion at the headwaters
Most deposition at the delta |
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What influences the pattern of a drainage basin? Why do you get a dendritic pattern versus a radial or rectangular pattern?
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Basin geology (structure, lithology, overburden), Climate, Developmental history, Slope
Dendritic - river channel follows slope of terrain, especially in valleys Radial - channel radiates outward from a high point, like a volcano Rectangular - channel follows rock joints that are at right angles |
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What is the difference betwteen tributary and distributary patterns? What two major landforms would you expect to see when water flows in a distributary pattern?
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Tributary streams flow together, and distributary streams split apart
Deltas, alluvial fans |
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Why do higher drainage densities occur in easily eroded rock? Why in deserts?
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Eroded rocks: greater surface area = higher drainage area = higher drainage densities
Since deserts have impermeable material that doesn't absorb much water, more water is drained because less infiltrates into the ground |
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Why do lower drainage densities occur in rocks that are harder to erode? Why in forests?
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Less eroded rocks: less surface area = lower drainage area = lower drainage densities
Since forests have permeable soil to absorb water, less water is drained because more infiltrates into the ground |
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What factors contribute to flash flooding?
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Intense rain
High drainage density + low permeability = rapid runoff Drainage basins with tributary patterns Narrow canyons where water can rapidly rise |
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You see a muddy stream, grab a water bottle and collect a sample. You pour it out in an open container. It takes awhile for the water to clear. Why?
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Muddy water has a lot of suspended sediment that only needs a low velocity to stay suspended, so it takes awhile for the velocity to decrease to the point where sediment begins to settle
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Braided:
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lots of cobbles and gravel, islands in the channel, common in deserts and in front of melting glaciers, shallow depth and wide width = high width:depth ratio
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Meandering:
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lots of silt and clay on banks, island rare, common in humid areas, deep depth and narrow width = low width:depth ratio
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How are goosenecks made?
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The amplitude/wiggling of the meander increases, deposition at point bars occurs, erosion at cut banks occurs, and a high velocity zone of water swings from cutbank to cutbank, thereby creating a gooseneck shape
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How are natural levees made along meadering streams?
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They build up after every flood from the heaviest sediments that have dropped closest to the channel
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What is the connection between bankfull discharge and avulsions?
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In a single channel stream, bankfull is the discharge that just fills the channel without flowing onto the floodplain. If bankfull discharge is exceeded, it causes avulsion, which is the process by which a river's flow permanently changes from its usual path to new path on the adjacent floodplain.
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Oxbow lakes tell you something about the history of a stream. What?
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Oxbow lakes, which form when an abandoned part of stream channel fills with stagnant water and is permanently cut off from the channel, reveal that the stream at one time followed a different path.
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Perennial:
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flows year round, discharge supplied in part by baseflow, found in humid regions
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Intermittent
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flows during wet seasons, flows when the water table is high, found in semi-arid areas
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Ephemeral:
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flows when it rains hard, water table always below the channel, found in deserts
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Where would go to find streams with high competence?
Where would go to find streams with high capacity? |
Competence is the maximum size particle that the stream can transport.
Aptos Creek has high competence. Capacity is the maximum amount of material that the stream can transport. The Mississippi River has high capacity. |
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What does it mean by saying that the magnitude of a flood is inversely related to the frequency of a flood?
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Smaller floods happen more frequently and bigger floods happen less frequently.
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What is Q? How is it measured? If you are given a stream's width, depth and velocity, can you calculate the stream's discharge?
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Q is discharge, which is measured by multiplying width x depth x velocity
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How would you change (increase or decrease) these variables to slow the velocity of a stream?
R, hydraulic radius S, Slope n, roughness |
V = (R x S)/n
Decreasing the velocity of a stream would be accomplished by decreasing hydraulic radius, decreasing slope, or increasing roughness |
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What happens to a stream's type of flow (e.g. laminar, turbulence) as velocity increases?
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As velocity increases, so does the Reynold's Number. When the Reynold's Number is around 500, the flow is laminar. When the Reynold's Number is 2,000 or bigger, the flow is turbulent.
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A waterfall is an example of a _____.
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Knickpoint
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A _____ valley is formed by fluvial erosion.
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V-shaped
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A ____ ____ is a stream in balance. This means all the _____ input into the fluvial system can be transported ____ of the system.
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Graded stream
Energy Out |
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A concave upward longitudinal profile is indicative of a ____ stream.
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Graded
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Which of the following best describes Base Level:
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The subterranean elevation below which a stream cannot vertically erode sediment. This hypothetical elevation is usually sea level.
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Which of the following is NOT a way a stream changes downstream?
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Stream changes downstream when:
Discharge increases Slope decreases Roughness decreases Net forward velocity increases Drainage area increases Load increases Particle size decreases |
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Would you rather dive into a stream's riffle or pool? Would you rather dive into a stream next to the point bar or next to the cut bank?
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Pool because it's deeper than a riffle
Cut bank because the velocity of the water has carved it deeper (The point bar is collecting sediment) |
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If a stream is grade, would you expect to see waterfalls and other types of knickpoints?
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equilibrium. Waterfalls and other knickpoints occurs in streams that are trying to reach equilibrium but not at it.
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How does a stream remove a knickpoint, and attempt to reach a graded condition?
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Through undercutting, falls and basins, and an eroding bed
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What is base level?
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The subterranean elevation below which a stream cannot vertically erode sediment. This hypothetical elevation is usually sea level.
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Why do deltas form at base level?
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Deltas occur where rivers meet oceans, which are located at sea level, the typical elevation for the base level.
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Can a dam create a new base level for a stream?
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Yes because they deposit the delta above the dam and erode below the dam, thereby reversing the base level in that particular area.
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What happens to the river upstream of a dam?
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Upstream, the base level rises and the valley fills in (aggradation).
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What happens to a river downstream of a dam?
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Downstream, the base level falls and the valley erodes deeply (incision).
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How would a rising base level influence deposition in a stream?
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Rising base level causes aggradation, which is an increase in the deposition of bedload.
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Stream terraces are former __________ of a river
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Floodplains
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The city of Mesa sits on a ____ ____.
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Stream terrace
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Which of the following is NOT a way to increase total energy into a fluvial system:
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Total energy increased by:
Increase in gradient (aggradation); decrease in base level (drop in sea level, degradation of higher order stream); uplift of mountains; overflow of lakes; increase in low sediment discharge from tributaries (from climate changes or extreme storms) |
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What is the difference between a strath and a fill terrace?
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Strath terrace is erosional (safe)
Fill terrace is depositional (unsafe) |
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ENSO is an acronym for ______
and this impacts Arizona in the ____ |
El Nino Southern Oscillation
Winter |
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Major floods along the Salt River occur during (winter or summer?) and are often associated with what atmospheric condition?
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Winter
El Nino Southern Oscillation |
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The last ice age started about ______________ years ago, sending Earth into a series of _________ year-long cycles between glacial and interglacial fluctuations.
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2.5 million
100,000 |
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The most popular explanation for these glacial-interglacial cycles involves changes in what aspects of Earth's orbit?
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Shape of orbit (eccentricity)
Tilt of axis (obliquity) Direction of axis (precession) |
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Why would changes in Earth's orbit cause fluctuations between glacial and interglacial fluctuations?
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All three elements of orbit change over time and create long-term fluctuations in the amount of solar radiation that reaches the earth (insolation).
The larger the eccentricity, the greater the difference in insolation. If there was no obliquity, there would be no seasonal change in insolation. The larger the obliquity, the greater the difference in seasonal temperatures. Changes in precession affect the accumulation of ice and snow at the poles. |
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What is the most important cause of the Little Ice Age?
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Solar radiation decreased
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Loess is?
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Deposits of silt laid down by wind during glacial and postglacial times
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Why would loess occur on the margins of ancient ice caps?
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Drainage winds moved outward from the ice sheets and deposited silt around the margins
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The largest area of loess deposition in the United States can be found _________.
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Midwest/Great Plains
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Stone rings, pingoes, and rock glaciers and other ___________ activity became more common during ice ages.
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Enhanced periglacial
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Sea level ________ about 130 meters in the last glacial maximum. Why?
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Decreased
Glacial/interglacial fluctuations moved water from the oceans to the ice. (Today, if glaciers melted, the sea levels would rise - so the opposite happened during ice ages. Glaciers increased, so sea levels fell.) |
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____ _____ refers to the response of the crust to loading and unloading of continental ice sheets.
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Glacioisostatic response
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Did plants change in response to the change from glacial to interglacial conditions?
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Yes
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When you see a playa like the Bonneville salt flats, this means that....
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There was a lake located there in glacial times
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Today, you can drive from Salt Lake City, Utah, to Reno, Nevada straight across falt desert grabens. How was this different in the last ice age?
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It used to be a large ancient lake (paleolake)
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Why is land rising in Scandinavia, the Northeastern United States and Canada?
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Continental ice sheets are unloading, so the crust is rebounding upwards in response to the weight being removed
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Geologists from the 1930s through the 1970s refused to believe J. Harlen Bretz, that giant floods of biblical proportion flowed across what is now the _______________ (two words).
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Pacific Northwest
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Why did they refuse to believe Bretz? HINT: Paradigm
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Uniformitarianism
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What changes as snow undergoes a metamorphosis to glacial ice?
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Density
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The intermediate stage between Snow and Glacial Ice is called _____.
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Firn
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Why is a bergshrund important to geomorphologists?
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They can see how glacial ice is lost (ablation)
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Glaciers ablate by ______, _______, and _____________.
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Calving
Melting Sublimation |
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Louis Agassiz fought the general perception of the Church that giant boulders in the Alps were caused by ___________ (two words), instead of glaciers.
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Noah's Flood
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You hike up into the highest peaks of the Sierra Nevada and notice tiny
glaciers on the shaded northeastern sides. You remember that these glaciers are above the ____ snowline, but still at a lower elevation than the ____ snowline, where sun would normally melt them. |
Orographic
Climatic |
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The ____________ separates the accumulation zone and the __________ (two words) of a glacier.
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Equilibrium line
Ablation zone |
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When accumulation > ablation, the glacier front __________.
When accumulation is < ablation, the glacier front _________. When accumulation = ablation, the glacier front _______________. |
Advances
Retreats Is Stable |
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Rank processes of glacial movement from slowest to fastest.
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Internal Deformation
Basal Regelation Slip Bed Deformation |
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What is at the bottom of an alpine glacier that would allow it to move fast?
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Meltwater
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Glacial crevasses are __________ in a glacier. They can form by ___________ or _____________.
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Cracks
Extension Compression |
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If you wanted to hold a concert in a mountain setting, the perfect glacial landform would be a _________, because it naturally has amphitheater shape.
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Cirque
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You are camping next to a rock bound lake in the mountains called a ________.
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Tarn
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A pyramid-shaped mountain surrounded by glacial cirques is called a _________
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Horn
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To hike between two glacial valleys, you would either have to go over a very sharp knife-like ridge called a ___________ or a gentle pass called a ___________.
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Arete
Col |
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The Matterhorn, in the Swiss Alps, is an example of a ____. (See image)
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Horn
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Yosemite Valley has many tribuatry valleys that are called ____ ____. (See image)This image shows what type of landform: (See image)
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U-shaped valleys
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Hanging valleys, fjords, paternoster lakes, glacial staircases are all associated with what basic glacial landform?
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Glacial trough
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What changed between today's fjord landform and when they were made by glaciers?
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Used to be only fresh water; now filled with a mixture of fresh water and sea water
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What is a major difference between how a glacial tributary meets the main glacier and how a stream tributary meets the main stream?
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Difference in elevation causes hanging valleys.
Tributary streams enter the main stream at the elevation of the main channel. But during glaciation, tributary glaciers feeding into the main valley are smaller and do not erode their valleys as deep as the glacier that occupies the main valley. Tributary valleys are left hanging at a higher elevation above the main valley floor as a result of more intensive downward cutting by the main valley glacier. |
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A deposit of boulders, cobbles, sand and clay -- a mixture of particle sizes (unsorted) -- characterizes lahaars, debris flows and _______.
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Till
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Moraines are _____.
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Ridges of tills
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Medial Moraine:
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middle ridge made by a combination of lateral moraines
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Terminal Moraine
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ridge representing the maximum extent of the glacier
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Recessional Moraine
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like a terminal moraine, but deposited where the glacier stops for a bit as it retreats
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Lateral Moraine
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ridge of till deposited on the side of the glacier
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Ground Moraine
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left behind as glacier retreats
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What is the difference between a medial moraine, lateral moraine and terminal moraine?
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Medial: middle ridge
Lateral: side ridge Terminal: end ridge |
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Why do you think the deposit in front of a glacier is called outwash? Is it deposited by glaciers or another process?
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Drift causes till to wash out in front of a glacier
Deposited by meltwater streams at the edge of a glacier |
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You see a beautiful blue turqouise color in a stream. You know that the cause of the color is due to the presence of ____________.
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Glacial flour (suspended sediment composed of ground-up rock)
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You are standing on a small mountain called a(n) _____________ surrounded by an ice cap.
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Nunatak
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Why do areas that once accumulated a continental glacier (like Ireland, Canada, Sweden) have so many lakes?
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Glacial ice scours out a place for lakes
Fills up lakes Glacial ice retreats Isostatic rebound |
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Long (several football fields), narrow cigar-shaped hills called ___________ can indicate the direction of a(n) ________ glacier.
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Drumlin
Continental |
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Long Island, Cape Cod, and hills in eastern Washington all tell you what?
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They are terminal moraines
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A large area of ice separates from the moving section of a continental glacier. It stagnates and melts in place. What landforms would you expect to see?
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Kames
Kettle lakes Esker Recessional moraines |
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What landform would you expect to see right in front of the end moraine of a continental glacier?
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Outwash plain
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There are two theories to explain Drumlin formation. Which of the following are the two theories?
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Deformational Theory
Fluvial Theory |