GLY 101:Final Exam
161 Cards in this Set
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What are the two types of weathering?
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mechanical
chemical
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Frost Wedging
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Water inside rock fractures expands when freezing by 9%. Expands and enlarges pre-existing fractures.
Breaks rocks into angular fragments Pronounced in mountainous regions Can form talus slopes at base of steep cliffs
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Salt Crystal Growth
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Growth of salt in fractures can split rocks apart.
Common around shorelines and arid environments.
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Thermal Expansion
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Application of intense heat resulting in rock spalling (typically 1-5 cm thick)
low thermal conductivity of rocks; little inward transfer of heat differential internal and external stresses forest fires
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Unloading
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concentric slabs of igneous rock break as overlying material is removed.
layered slabs have an onion-like "peeled" appearance creates exfoliation domes different from joints
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Dissolution
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Water removes in solution from a pre-existing mineral
Greatly facilitated by a slightly acidic solution Calcite dissolution Makes caves and sink holes
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Hydrolysis
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Reaction between mineral elements and the hydrogen ion of dissociated water. (metallic cations replaced by Hydrogen cations).
Very important for breaking down of silicates
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Oxidation
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Chemical reaction involving the loss of electrons
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Rusting
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4 Fe (iron) + 3O2 (oxygen) --> 2Fe2O3
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What is the order of resistance to weathering for silicate minerals?
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Olivine, Pyroxene, Calcium Feldspar, Amphibole, Biotite, Sodium Feldspar, Potassium Feldspar, Muscovite, Quartz.
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Where are physical weathering processes dominant?
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Dominant in regions with adequate precipitation and temperatures near freezing.
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Soil
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Combination of unconsolidated mineral and organic matter, water and air at the Earth's surface.
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Regolith
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Layer of coarse rock and fragments; transition from soil to underlying bedrock.
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Parent Material
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underlying bedrock or consolidated deposits
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Climate
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Temperature or precipitation
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Biota
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(plants and animals) organic matter, organic acids, microorganisms, burrowing animals, plant roots.
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Topography
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(slope) steepness controls erosive energy, slope orientation, drainage
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Time
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weathering processes and soil depth layering
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What are the controls of soil formation?
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parent material
climate Biota Topography Time
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Describe the processes and characteristics of the typical horizons in a soil profile.
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O horizon: organic
A horizon: mixture of mineral and organic material E horizon B horizon: subsoil accumulation of clay and inorganic soil components C horizon: transition to bedrock
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How are soils classified?
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Soil taxonomy
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What are some of the processes and factors associated with soil erosion?
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rain splash impact
sheet erosion rill erosion gullies
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Why is soil erosion such a big problem?
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stream-channel sedimentation
reservoir siltation hydrophobic contamination loss of arable land
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Mass Wasting
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downslope movement or rock, regolith, and soil by gravity;
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What are some “triggers” of mass wasting events or episodes?
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pore space saturated
oversteepening beyond angle of repose vegetation removal Earthquakes
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Angle of Repose
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25 degrees to 40 degrees
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How are mass wasting events classified?
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type of material
type of motion rate of movement
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What are the three types of mass wasting events based on motion?
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Slump
Rockslide Debris Flow
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Slump
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downward sliding of rock or unconsolidated soil as one discrete unit along a curved failure plane; not particularly fast or long; rotational slide
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Rockslide
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blocks of bedrock break loose and fall down slope
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Debris Flow
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rapid event; flow of soil and regolith with large amount of water.
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Earth Flow
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typically slower than debris
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Flow
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saturated hill slopes in human regions
leaves a scar and forms a tongue at the base mostly cohesive silt and clay
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Creep
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gradual downslope movement of soil and regolith; more widespread
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Hydrological Cycle
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circulation of Earths water supply; powered by solar energy;
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What is the most important agent in modifying the Earth’s surface after land is created?
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running water
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Describe the differences between sheet flow, rill flow, and gully flow.
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sheet flow initiates as broad, thin sheets on the ground
rill flow is concentration of sheet flow into small temporary channels gullies are semi-permanent channels for runoff
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Infiltration Capacity
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Limitation of a soil to allow precipitation to enter the soil and groundwater system
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Drainage Basin
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land area that contributes water and sediment to a river system; separated by divides
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Laminar Flow
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Water particles move in parallel paths directly down the stream channel
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Turbulent Flow
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water particles generally move down stream, but temperatures move in different directions
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What are two factors that affect the velocity of running water in a stream?
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channel slope
channel roughness
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Stream Discharge
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Volume of water flowing past a cross-sectionof a stream channel for a specified duration.
Q=A
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Name some of the largest rivers in the world based on stream discharge.
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Amazon
Congo Yangtze Mississippi (7)
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Longitudinal Profile
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elevation of the stream channel from its headwaters to its outlet
also adjusts downstream
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Suspended Load
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mineral particles that remain in the water column
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Dissolved Load
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occur as ions in solution, usually from ground water entering strews...about 4 billion metric tons/years to oceans
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Bedload
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coarse particles that move or skip along the stream-channel
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Traction
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slide or roll along bed
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Saltation
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skip along bed
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Capacity
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Greatest amount of sediment that a stream can transport
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Competence
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largest particle size a stream can transport
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Alluvial Streams
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flow through sediment that it has deposited. Sensitive to increases or decreases in discharge and sediment load
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What are the two major controls of alluvial channel morphology (shape)?
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discharge
sediment load
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What are the two major stream channel patterns?
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braided
meandering
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Base-level
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elevation at which streams ultimately erode down
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Graded-level
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adjusted its morphology to transport the amount and size of sediment contributed to it
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Stream Valley
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includes the channel, floodplain, and terrace deposits
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How are stream valleys formed?
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formed by channel incision and widening
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Floodplain
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consists of alluvial sediment deposited by the stream channel and deposited by the stream channel and occurs at an elevation that regularly floods
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Natural levees
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elevated deposits of sediment that occur along the edge of a stream channel. They are deposited as relatively coarse-grained sediment (sand) falls out of suspension when velocity decreases out of the channel during a flood.
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Back Swamps
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Fine-grained sediment deposited by floods away from the channel in the flood plain.
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Terraces
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former flood plain surfaces that are "stranded" above the active flood plain
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Deltas
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deposited when a stream enters a lake or ocean. Flow velocity slows down and sediment is deposited into sloped fore set beds. Horizontal top set beds formed during flood stage and bottom set beds of tine particles of shore.
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Alluvial Fan
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deposited when the slope of a stream is rapidly reduced. Usually occur at base of a mountain range. Most common in arid settings.
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Stream Piracy
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occurs when headward erosion overtime of a relatively steep stream captures another stream
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How are floods statistically analyzed?
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floods are statistically analyzed as a recurrence interval
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Hydrograph
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plot of discharge through time
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What are some of the ways we attempt to control floods?
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dams
levees channelization
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Groundwater
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typically does not exist as "underground rivers", but usually fills the small pore spaces between rock particles. In highly dissolvable rocks, conduits can contain and transport groundwater. Represents the largest reservoir of fresh water available for human use.
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zone of soil moisture
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retention of molecular water as a surface film on soil particles; unsaturated zone
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zone of saturation
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all open pores are filled with water...top of this zone is the water table
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How are groundwater levels measured?
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water-table elevations measured at wells and spring locations. Groundwater flows from high to low water tables
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Gaining Streams
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groundwater contributes to stream flow; water table above stream
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Losing Streams
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surface water contributes to groundwater; water table is below the stream
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Porosity
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amount of pore space between solid particles in a rock or sediment
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Permeability
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degree of connection between pores-->ability to transmit fluid through rock
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aquitard
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impermeable rock layers
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aquifer
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permeable rock layers containing usable water
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Hydraulic Gradient
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slope of the water table; the higher the gradient, the faster the groundwater velocity
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Hydraulic Conductivity
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measure of the permeability of different rock types; also accounts for fluid viscosity
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Perched Water Table
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local aquitard creates local zone of saturation aboce regional ground water table
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What are some of the different mechanisms that cause springs?
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depression spring, contact spring, fault, sinkhole, joint, fracture
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Drawdown
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is a localized drop in the water table elevation because of pumping at wells
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Cone of Depression
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is a result from drawdown; hydraulic gradient is increased and water flows faster to the well
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How do artesian wells occur?
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artesian wells flow because subsurface pressure causes a potentiometric surface subsidence, salt-water intrusion, fractured conduit dominated aquifer
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Why is salt-water intrusion so difficult to control?
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fresh water is less sense, so salt water floats to the top
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Karst
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refers to land forms and features associated with dissolution of the bedrock by ground water
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Glacier
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a thick mass of ice originating on land by accumulation, compaction, and recrystallization of snow; moves slowl
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valley glaciers
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stream of ice situated in mountainous valleys; start in highest elevations; commonly joined by tributary glaciers
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ice sheets
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large scale; cover topography beneath; flow out in all directions from one or more snow
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ice shelves
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extensions of ice sheets into the ocean; still attached to land, but float
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ice caps
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smaller versions of ice sheets
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outlet glaciers
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extend down valleys and drain ice sheets
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piedmont glaciers
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glaciers that fan out along lowland base of mountain ranges; fed by valley glaciers
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firn
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snowflakes become spherical; lose pore space; granular; 50 meters deep
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snowline
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elevation at which snow remains throughout the year; elevation is lowered towards the poles
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plastic flow
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movement with in the ice; pressure exerted that causes ice molecules to slide past one another
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zone of fracture
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brittle behavior near glacial surface
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zone of accumulation
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net gain of ice aboce snow line
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zone of wastage
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net loss of glacial ice below snowline
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plucking
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fractured bedrock loosens and is incorporated into moving glacier; can result in very large boulders in ice
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abrasion
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bedrock is "grinded" by moving ice; "polishes" rock.
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rock flour
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fine-grained particles of abraded rock
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glacial striations
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long scratches and grooves in bedrock caused by stones
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cirques
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bowl-shaped glaciers at top of mountain zone of accumulation
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horn
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sharp mountain peak "carved" on all sides by cirque glaciers
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morain
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eroded material concentrated along glacial margins
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tarn
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small pond at base of cirque (formed by plucking)
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hanging valley
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base of tributary valley well above base of glacial trough; creates waterfalls
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fjords
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deep inlets of the ocean surrounded by cliffs; U-shaped valleys at and beneath sea-level
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roche moutanee
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asymmetrical knob of bedrock caused by glacial abrasion
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glacial drift
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collective term for sediment of glacial origin
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till
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unsorted materials deposited by glaciers
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drift
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stratified sediment deposited by glacial melt water
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glacial erratics
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boulders embedded in till or dropped out of melting glacial ice
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lateral morain
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linear till deposits caused by plucking and abrasion along sides of valley glacier
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medial morain
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merging of lateral moraines when two valley glaciers converge
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end morain
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ridge of till at terminus of a valley glacier or ice sheet
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erminal morain
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furthest most extension of a continental ice sheet
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drumlins
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smooth, elongate hill made of glacial till; occur at base of continental ice sheets
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outwash plain
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stratified drift deposited by melt water rivers (braided).
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kettles
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depressions in till or drift marking where a chunk of glacial ice was surrounded by glacial deposits; melted leaving behind a "pond"
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kames
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steep-sided hill of drift (often associated with fan shaped deposits).
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Esker
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linear, elevated ridge of coarse gravel or sand deposited by melt water stream beneath retreating glacier (often in "conduits" through ice).
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eccentricity
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variations in shape of Earth's orbit around the sun (10,000 year cycle)
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obliquity
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changes in the angle that the axis makes with the plane of Earth's orbit (41,000 year cycle)
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precession
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wobbling of Earth's axis (26,000 year cycle)
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deflation
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removal of loose material by wind
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blow outs
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depressions caused by deflations; depth and width controlled by water table or vegetation
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desert pavement
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thin layer of coarse gravels resting above fine-grained sand and silt
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ventifacts
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sharp stones abraded by windblow sand
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yardangs
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stream lined, wind-sculpted bedrock land forms oriented parallel to the prevailing wind direction
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What are some characteristics of sand dunes?
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occur in deserts and beaches
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barchan dunes
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form when there is a limited supply of sand and a flat surface devoid of vegetation; one prevailing wind direction
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tranverse dunes
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form where there is a large supply of sand and no vegetation; oriented perpendicular to prevailing wind direction
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longitudinal dunes
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form where supply of sand is moderate; one overall wind direction with slight variations to push sand into ridges
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parabolic dunes
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form when vegetation stabilizes the horns, allowing the "middle" of the dune to continue downwind
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star dune
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form when there are variable wind directions and an ample supply of sand
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loess
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blanket-like deposits of wind blown silt
form from dust storms over deserts a glacial outwash deposits
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shoreline
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the line marking the contact between the land and sea
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shore
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the area extending from the lowest tide level to the upper limit affected by storm waves
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foreshore
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area exposed when tide is low and submerged during low tide
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near shore
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area affected by waves and submerged during low tide
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back shore
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submerged during storms
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bern
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elevated, flat, dry sand
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beach free
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slope down from bern to shoreline
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wave refraction
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bending of waves around a relatively shallow bottom
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longshore current
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obliquely striking waves generate current in surf zone
responsible for large quantities of sediment transport along beaches
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wave cut platform
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beveled surface below high tide at water level; physical grinding of rocks by wave-transported particles
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marine terrace
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evidence of former tectonic uplift
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What are some of the features along high-relief shores that are produced by wave erosion?
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sea arch
sea stacks
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spit
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curvilinear beach deposit formed by combination of long shore currents and wave refraction
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baymouth bar
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longshore current; cuts off estuary from ocean
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barrier island
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low ridged of sand that parallel the mainland coast formed by
a. erosion of cut through spit b. combination of breakers spilling sand up and storms elevating it above sea-level c. mainland sand
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What are the impacts of hurricanes
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storm surge
sustained wind >74 mph high waves inland flooding tornadoes
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jetties
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built into the ocean at the entrances to rivers and harbors; concentrate tidal currents that keep channels open
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groins
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barrier oriented perpendicular to shoreline; traps sand moving by longshore currents
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sea walls
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built parallel to the shoreline; defense against breaking waves
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breakwaters
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build just offshore to force breaking waves and reduce energy
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Why are tides different place to place?
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......
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GLY 101:Final Exam