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193 Cards in this Set

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geologic time scale

summarytimeline of all earth history, reflects currently accepted names of timeintervals for each segment of Earth’s history from vast eons through briefereras, periods and epochs

relative time

what happened in order; sequence of events based on the relative positions of rock strata above/below eachother; based on superposition- rock/sediment always are arranged with youngest beds "supoposed" toward the top of a rock formation and the oldest at the base if not disturbed

absolute time

actual number of years before the present; determined by scientific methods like radiometric dating


same physical processes active in the environment today have ben operating throughout geologic time


youngest epoch consisting of the last 11,500 years since the retreat of the continental glaciers


same physiacl processes active in the environment today have been operating throughout geologic time

where are the oldest materials in earths crust, and how old are they?

W. australia, 4.2-4.4 billion years old

how is earths interior sorted?

sorted in concentric layers, each distinct in chemical composition or temperature

how has the earth been thought to condense/congeal?

from a nebula of dust/gas/icy comets about 4.6 billion years ago

how does heat energy migrate?

it migrates outward from the center by conduction and physical convection in the more fluid or plastic layers in the mantle and neart the surface

inner core

thought to be solid iron that is well above the melting temperature, but remains sold bc of intense pressure


made of molten, metallic iron with lighter densities than the inner; fluid outercore generates at least 90% of earths magnetic field and the magnetopshere that surrounds and protects earth from solar, wind and cosmic radiation; circulation in outercore converts thermal and gravitational energy into magnetic energy producing earths magnetic field

zone of discontinuity

dividing earths outercore from the mantle, or a place where physical differences occur between adjoining regions in earths interior

80% of earths total volume

lower and upper mantle


rich in oxides of iron, magnesium and silicates which are dense adn tightly packed at depth, grading to lesser densities toward the surface

temperature in the mantle

gradual temperature increase with depth and a stiffening due to increased pressures

lower mantle

denser, thought to contain a mixture of iron, magnesium and silicates with some calcium and aluminum

upper mantle

divides into 3 distinct layers, upper mantle, asthenosphere and upper most mantle


made up of upper most mantle witht he crust


below lithosphere (aka plastic layer) contains pockets of increased heat from radioactive decay and is susceptible to slow convective currents in hotter/less dense materials; least rigid region of the mantle with densities avg. 3.3gcm^3; about 10% is molten in uneven patterns and hot spots; slow movement in this zone disturbs the overlying crust and creates tectonic activity

oceanic crust

basalt, granular and high in silica, magnesium and iton (can be called sima) thin and dense

continental crust

essentially granite, crystalline and high in silica, aluminum, potassium, calcium and sodium (can be called sial) about 2.7g/cm^3


explains certain vertical movement of earths crust due to bouyancy and balance; entire crust is in a constant state of compensating adjustment or ".." slowly rising and sinking in response as it is pushed/dragged and pulled over the asthenosphere


internal system builds landforms


external system wears down landforms

geologic cycle

give and take of the earths atmosphere; fueled from earths internal heat and solar energy from space influenced by leveling forces of gravity

what is the geologic cycle composed of?

hydrologic cycle (erosion, transportation and deposition) rock cycle (3 types of rocks found in the crust, igneous, sedimentary and metamorphic) tectonic cycle (brings heat energy adn new material to the surface and recycles materal, creating movement adn deformation of the crust


processes earths materials with chemical/physical action of water ice and wind

what is the most reactive gas in the lower atmosphere readily combining with other elements?



formed from earths elements; "song"

mineral is characterized by...

hardness, color, density etc

widespread mineral families are...

silicates (silicon/oxygen are common and readily combine with eachother and other elements; makes up 95% of earths crust)

oxides (oxygen combine with metallic elements like iron)

carbonates (carbon in combination with oxygen and other elements: calcium, magnesium, potassium)


assemblages of minerals bound together (granite) or a single mass of mineral (rock salt) or undifferentiaed material (obsidian) or solid organic material (coal)

why are continents adrift?

convection currents in the asthenosphere adn upper mantle dragging them around

Sir Francis Bacon

similarities between S. America and Africa

alfred wegener

"origins of the continents and ocean" father of continetnal drift (pangea in triassic period)

plate tectonics

include processes of upwelling magma; lithospheric plate movement (seafloor spreading) adn lithospheric subduction (earthquakes, volcanic activity) and lithospheric deformation (warping, folding and faulting)

sea floor spreading

mechanism that builds mountain chains and drives continental movement; submarine mountain ranges were mid ocean ridges adn the direct result of upwelling flows of magma from hot areas in the upper mantle and asthenosphere

magnetic tape recording in the sea floor

determined by earths reorientation of polarity during sea floor spreading

why is sea floor relatively young?

no more than 208 million years old becayse the farthest sections from the mid ocean ridges are slowly plunging beneath the continental crust and are reforming

divergent boundaries

characteristic of sea floor spreading centers where upwelling material from the mantle forms new seafloor and lithospheric plates spread apart (zone of tension) most ".." occur at mid ocean ridges, few occur within continents

convergent boundaries

characteristic of collision zones where areas of continental and oceanic lithosphere collide (zones of compression)

transform boundaries

occur where plates slide laterally past one another at right angles to a sea floor spreading center (no volcanic eruptions); spreading center mid ocean ridges are the location of transform faults

igneous rock

solidifies and crystallizes from a molten state; cooling history determines its physical characteristics. coarse grained (flower cooling) or fine grained/glassy (faster cooling); makes up approx 90% earths crust

intrusive igneous rocks

cools slowly in the crust, forms pluton

extrusive igneous rocks

formed through volcanic eruptions adn flows (lava that cools forms basalt)

how are igneous rocks classified?

through mineral composition and texture with 2 broad categories: felsic and mafic


derived both in composition and in name from feldspar and silica, high in silica, aluminum, potassium and sodium; low melting points, generally lighter in color and less dense


derived both in composition and name from magnesium and ferric; low in silica high in magnesium and iron; high melting points darker in color with greater density

sedimentary rock

solor energy and gravity drive the process of sedimentation with water; existin grock is disintegrated and dissolved by weathering, picked up/moved by erosion and transportation adn deposited along river, beach, ocean sites; involves lithification (process of cementation, compaction and hardening of sediments)

what are 2 primary sources of sedimentary rocks?

clastic sediments (formed from mechanically transported fragments of older rocks) and chemical sediments (from dissolved minerals in solution, some having organic origins) also biological

clastic sedimentary rocks

weathered and fragmented rocks that are further worn in transport provide clastic sediments; clast sizes range from boulders to microscopic clay particles and the form they take as lithified rock

chemical sedimentary rocks

formed not from physical pieces of broken rocl but from dissolved minerals, transported in solution and chemically precipitated from solution; once formed they are vulnerabe to chemical weathering

metamorphic rock

may be transformed from igneous/sedimentary; goes through profound physical/chemical changes under pressure and increased temperature; generally more compact than original rock adn are harder/most resistant to weathering/erosion; compressed during collisions between slabs of earths crust

continental landmasses

portions of crust that reside abover or near sea level including the undersea continental shelves along coastlines

ocean basins

enirely below sea level

tectonic activity

driven out by planets internal energy builds crust while exogenic processes of weathering/erosion, powered by the sun through actions of air, water, waves and ice tear down crust, generally slow requiring millions of years

what is the craton or heartland region of the continental crust?

Allcontinents have a nucleus of ancient crystalline rock on which the continent“grows” witht eh addition of crustal fragments and sediments;Cratons are generally eroded to a low elevationand relief; most date to Precambrian and can be more than 2 billion years old

continental shield

region where a craton is exposed at the surface

what are three types of stress?

tension (stretching), compression (shortening) and shear (twisting/tearing); stress is a force and the resulting strain is the deformation in the rock

fault zones

areas where fractures in the rock demonstrate crustal movement; at the moment of a fracture, a sharp release of energy occurs producing an earthquake

fault plane

fracture surface along which the two sides of a fault move

when does a normal fault form?

when rocks are pulled apart by tensional stress; when the break occurs rock on one side moves vertically along aninclined fault plane, the downward shifting side is the hanging wall, it dropsrelative to the footwall block; a cliff formed by faulting is commonly called afault scarp/escarpmentts"

when does a thrust/reverse fault form?

when rocks are forced together by compressional stress; converging plates force rocks to move upwardalong the fault plane; appears similar to a normal fault although but with morecollapse and landslides occur from the hanging wall component

when does a strike slip fault form?

when rocks are torn by lateral shearing stress; themovement is right lateral or left lateral depending on the motion perceivedwhen you observe movement on one side of the fault relative to the other side;can create linear rift valleys


birth of mountain; mountain building; net result of this accumulating material is a thickening of the crust

oceanic-continental plate collisions

occurring along the pacific coast of theAmericas and has formed the andes and sierra of central America; there arefolded sedimentary formations with intrusions of magma forming granitic plutonsat the heart of these mountains; active around the pacific rim, thermal innature because the dividing plate melts and migrates back toward the surface asmolten rock; known as circumpacific belt or ring of fire

oceanic-oceanic plate collision

collisions can either produce simple volcanicarcs or more complex arcs such as Indonesia and japan (which includedeformation and metamorphism of rocks and granitic intrusions) these processesformed the chains of island arcs and volcanoes that continue from thesouthwestern pacific to the western pacific, and the Philippines; active aroundthe pacific rim, thermal in nature because the dividing plate melts andmigrates back toward the surface as molten rock; known as circumpacific belt orring of fire

continental-continental plate collision

largemasses of continental crust are subjected to intense folding, overthrusting,faulting and uplifting; converging plates crush and deform both marinesediments and basaltic oceanic crust; (ex. formation of European alps); as aresult of such compression forces includes considerable crustal shortening,formed great overturned folds called nappes

focus/hypocenter of an earthquake

subsurface area along a fault plane where the motion of seismic waves is initiated

what is the area at the surface directly above the focus called>


what are tectonic earthquakes associated with?



instrument used to record vibrations transmitted as waves of energy throughout earth's interior and in the crust; this device helps scientists to rate earthquakes on a qualitative and quantitative level

qualitative scale

damage intensity scale

quantitative scale

magnitude of energy released scale

mercalli scale

measure damage intensity on a roman numeral scale 1-12

richter scale

a system designed to estimate earthquake magnitude, records the amplitude of seismic waves; is logarithmic where each whole number represents a ten fold increase in the measured wave amplitude

elastic rebound theory

how a fault breaks; 1. Generally, two sides along a fault appear to belocked by friction, resisting any movement despite the powerful forces actingon the adjoining pieces of crust 2. Stress continues to build strain along the faultplane surfaces, storing elastic energy 3. When strain build up finally exceeds frictionallock, both sides of the fault abruptly move to a condition of less strain,releasing a burst of mechanical energy

how many volcanoes erupt worldwide per year?



forms at the end of a central vent/pipe that rises from the asthenosphere and upper mantle through the crust into a volcanic mountain


circular surface depression usually forms at or near the summit

lava (molten rock)

gases and pyroclastics pass through the vent to surface and build the volcanic landform; can occur in many different textures and forms which accounts for the varied behavior of volcanoes adn the different landforms and their origins

location of volcanic mountains on earth is a function of...

plate tectonics and hot spring activity

volcanic activity occurs in 3 settings

1.Along subduction boundaries at continentalplate-oceanic plate convergence (Mt. St. Helens) or oceanic plate-oceanicconvergence (Philippines/Japan)2.Along seafloor spreading center on the oceanfloor (Iceland on Mid Atlantic Ridge) and along areas of rifting on continentalplates (rift zone in E. Africa)3. At hot spots where individual plumes of magmarise to the crust (Hawaii and Yellowstone)

what are the factors determining an eruption?

1. Magmas chemistry (related to its source) 2. Magmas viscosity (resistance to flow “thickness”)

what are the 2 types of eruptions?

effusive and explosive

effusive eruptions

relatively gentle but produce enormous volumes of lava annually on the seafloor and in Hawaii and Iceland; direct eruptions from the asthenosphere and upper mantle produce low viscosity magma that is fluid and cools to form a dark basaltic rock low in silica and rich in iron and magnesium; gases readily escape from this magma bc of low viscosity, adding to a gentle eruption with relatively small explosions and few pyroclastics
• Typical mountain landform built from effusive eruptions is gently sloped, gradually rising from the surrounding landscape to a summit crater ; known as a

shield volcano

explosive eruptions

volcanic activity inland from subduction zones produces explosive volcanoes; magma produced by the melting of subducted oceanic plate and other materials is thicker (more viscous) than magma that forms from effusive volcanoes, it is 50-75% silica and high in aluminum, consequently it tends to block the magma conduit inside the volcano, the block traps and compresses gases causing pressure to build for a possible explosive eruption

composite volcano

- is a explosively formed volcano (stratovolcano) built up in alternating layers of ash, rock and lava; tend to have steep sides, are more conical in shape; high viscosity , rising magma forms a plug near the surface where the blockage causes tremendous pressure, it then erupts producing much less lava than effusive, but larger amounts of pyroclastics (volcanic ash, dust, cinders, lapilli, scoria, pumice and aerial bombs (blobs of lava that were ejected)

nuee ardente

"glowing coud" is an incandescent, hot, turbulent fas, ash and pyroclastic cloud that can jet across the landscape in an eruption

low viscosity

very fluid

high viscosity

thick and flowing slowly


science of landsforms, their origin, evolution, form and spatial distribution


any process that wears away or rearranges landforms; principal denudation processes affection surface materials include weathering, mass movement, erosion, transportation, and deposition as produced by the agents of moving water, air, waves and ice (all influenced by the pull of gravity)


an open system with highly variable inputs of energy and materials

potential energy of position

created by uplift above sea level and therefore disequilibrium and imbalance between relief and energy

heat energy

converted from suns radient energy

kinetic cycle

imparted through the hydrologic cycle through mechanical motion

chemical energy

made available from the atmosphere and various actions within the crust

geomorphic threshold

point at which energy overcomes resistance against movement; system breaks through to a new set of equilibrium relationships as the landform and its slopes enter a period of adjustment and realignment


process that breaks down rock at earth’s surface and to some depth below the surface, either disintegrating rock into mineral particles or dissolving it in water; this process is both physical (mechanical) and chemical; the interplay of the 2 is complex, often forming a synergy, a combined action, as the suite of processes work the rock


parent rock from which weathered regolith and soils develop

factors influencing weathering processes

- Rock composition and structure (jointing): jointing in rock is important for weathering processes; joints are fractures or separations in rock that would occur without displacement of the sides- Climate: precipitation, temperature and freezethaw cycles are the most important factors affecting weathering - Subsurface water- influences through water table level and water movement within soil and rock structures- Slope orientation: geographic orientation of a slope; whether it faces north, south, east or west, controls the slopes exposure to sun, wind and precipitation; slopes facing away from the sun’s rays tend to be cooler, moister and more vegetated than slopes in direct sunlight- Vegetation: can protect rock by shielding fit from raindrop impact and providing roots to stabilize soil; also produces organic acids from partial decay of organic matter; plant roots can enter crevices and break up a rock

physical weathering

when rock is broken and disintegrated without any chemical alteration (aka mechanical weathering); by breaking up rock, physical weathering produces more surface area on which chemical weathering may operate

types of mechanical weathering

- Frost action: when water freezes its volume expands as much as 9%, this expansion creates a powerful mechanical force which can exceed the tensional strength of rock; repeated freezing/expanding and thawing/contracting of water breaks rocks apart; joint block separation- occurs along existing joints and fractures; frost wedging- ice begins in small openings gradually expanding until rocks are cleaved or split- Salt crystal growth (salt weathering): dry weather draws moisture to the surface of rocks, as the water evaporates, dissolved minerals in the water grow crystals In a process known as crystallization - Pressure release jointing: layer after layer of rock peels off in curved slabs or plates, thinner at the top of the rock structure and thicker at the sides; as these slabs weather, they slip off in the process of sheeting; this exfoliation process creates arch shaped and dome shaped features on the exposed landscape

chemical weathering

chemical breakdown of the constituent minerals in rock, always it the presence of water; chemical decomposition and decay become more intense as both temperature and precipitation increase; ex). spheroidal weathering- water penetrates joints/fractures and dissolves the rocks weaker minerals or cementing materials

types of chemical weathering

- Hydrolysis: when minerals chemically react with water; decomposition process that breaks down silicate minerals in rocks; involves water and elements in chemical reactions to produce different compounds; ex). weathering of feldspar minerals in granite can be caused by a reaction to the normal mild acids dissolved in precipitation; granular disintegration- when weaker minerals in rock are changed by hydrolysis, the interlocking crystal network breaks down so the rock fails, this is when “…” takes place- Hydration: “combination with water” little chemical change, water becomes part of the chemical composition of the mineral- Oxidation: certain metallic elements combine with oxygen to form oxides; most familiar is rusting; as iron is removed from the minerals in a rock, the disruption of the crystal structures makes the rock more susceptible to further chemical weathering and disintegration- Dissolution of carbonates: when a mineral dissolves into solution; water is universal solvent bc its capable of dissolving at least 57 of the natural elements and many of their compounds; carbonation- a reaction whereby carbon combines with minerals, dissolving them

characteristics of limestone

abundant on earth and composes many landscapes; these areas are susceptible to chemical weathering, which creates a specific landscape of pitted, bumpy surface topography, poor surface drainage, and well developed solution channels

karst topography

approx.. 15% of earth’s land area has some karst features with outstanding examples found in southern china, japan, Puerto rico, cuba the Yucatan of mexico, Kentucky, Indiana, new mexico and florida; approx.. 28% of Kentucky has sinkholes and related karst features noted on topographic maps

for a limestone landscape to develop into karst topography, several conditions are necessary

- Limestone formation must contain 80% of more calcium carbonate for dissolution processes to proceed effectively- Complex patterns of joints in the otherwise impermeable limestone are needed for water to form routes to subsurface drainage channels- An aerated (containing air) zone must exist between the ground surface and water table- Vegetation cover is required to supply varying amounts of organic acids that enhance the dissolution process

where does karst occur>

in arid regions, but primarily due to former climatic conditions of greater humidity


weathering of limstone landscapes create sinkholes which form in circular depressions; collapse sinkhole forms if such a solution sinkhole collapses through the roof of an underground cavern

karst valleys can be formed from....

the continuation of solution and collapse which coalesce to form a karst valley which is an elongated depression up to several km long

in wet tropics, karst topography forms in deeply joined...

thick limestone beds

where do caves form?

• caves generally form just beneath the water table where later lowering of the water level exposes them to further development



grow from the ceiling

build from the floor

mass movement

any unit movement of a body of material propelled and controlled by gravity; can be surface processes or submarine landslides beneath the ocean; content can range from dry to wet, slow to fast, small to large and free falling to gradual/intermittent

mass wasting

general process involved in mass movements and erosion of the landscape

angle of repose

steepness of something; angle represents a balance of the driving force (gravity) and resisting force (friction/shearing); the angle ranges for various materials at 33-37 degrees and for snow avalanche slopes between 30-50 degrees

what materials are highly susceptible to hydration?

clays, shales and mudstones

what are the 4 classes of mass movement?

rock fall, debris avalanche, landslides, flows and creep

rock fall

volume of rock that falls through the air and hits a surface; during “..” individual pieces fall independently and characteristically form a cone-shaped pile of irregular broken rocks on a talus slope at the base of a steep incline

debris avalanche

mass of falling/tumbling rock, debris and soil; speed often results from ice and water that fluidize the debris avalanche results from its tremendous speed and ack of warning; Peruvian Andes 1970, earthquake initiated the event and upward 100 million m^3 of debris buried the city of Yungay, where 18,000 people perished and the avalanche attained velocities of 300kmph


sudden rapid movement of a cohesive mass of regolith/bedrock that is not saturated with moisture; large amount of material failing simultaneously; to eliminate the surprise element scientists use the GPS to measure slight land shifts; slides occur in 2 basic forms:1. Translational slides- movement along a planar (flat) surface toughly parallel to the angle of the slope with no rotation; ex). Madison Canyon slide; flow and creep patterns are also considered “…” in nature2. Rotational slides- occur when surface material moves along concave surface; underlying clay presents an impervious surface to percolating water, so water flows along the clay surface; ex). La Conchita, California


include earth flows and more fluid mudflows; heavy rains can saturate barren mountain slopes and send them moving


persistent gradual mass movement of surface soil; individual soil particles are lifted/disturbed by the expansion of soil moisture as it freezes by cycles of moistness and dryness; in freeze thaw cycle particles are lifted at right angles to the slope by freezing soil moisture, but when the ice melts the particles fall straight downward in response to gravity; fence posts, trees go down with; strategies used to arrest the movement are grading the terrain, building terraces and retaining walls

what do rivers do?

• Rivers redistribute mineral nutrients important for soil formation and plant growth, and serve society in many ways• Shape the landscape by removing products of weathering, mass movement and erosion and transporting them downstream• Rivers provide with essential water supply and receive, dilute and transport wastes, provide critical cooling water for industry and for, one of the world’s most important transportation networks


science of water and its global circulation, distribution and properties, specifically water at and below earth surface


streamflow volume past a point in a give unit of time

rivers with greatest stream discharge

amazon, congo, yangtze, orinoco and in US missouri-ohio-mississippi, st. lawrence and mackenzie river systems

what are the driving forces of the fluvial systems

insolation and gravity power the hydrologic cycle


process of water dislodging, dissolving and moving surface material• Streams produce fluvial erosion in which weathered sediment is picked up for transport to new locations; thus a stream is a mixture of water and solids; the solids are rolled/carried by mechanical transport or move in a dissolved solution; materials are laid down by the process of deposition


clay, silt, sand, gravel and mineral fragments deposited by running water, which can be semi/sorted sediment on a floodplain, delta or streambed

base level

a level below which a stream cannot erode its valley, ultimate base level is sea level, the average between high/low tides

local base level

(or temporary) may control the lower limit of local streams for a region; local base may be a rover, lake, hard/resistant rock, or the reservoir formed by a human made dam

landforms are produced by 2 basic processes...

1. Erosive action of flowing water 2. Deposition of stream transported materials• Drainage basin- ever stream has

drainage basin

every stream has a “..” ranging in size from tiny to vast; ridges form drainage divides that define the catchment (water receiving) area of every drainage basin; ridges are dividing lines that control into which basin runoff water from precipitation drains

how does water flow in a drainage basin?

• In any drainage basin, water initially moves downslope in a thin film of sheetflow or overland flow


small scale downhill grooves that may develop into deeper gullies and then into a stream in a valley

continental divides

are situated in the US and Canada, are extensive mountain and highland regions separating drainage basins, sending flows to the Pacific, Gulf of MX, Atlantic, Hudson bay or Arctic ocean; these divides form water resource regions and provide a spatial framework for water management planning

drainage basins as open systems

ex. Danube river; inputs include, precipitation and minerals of rocks of the regional geology; energy and materials are redistributed as the stream constantly adjusts to its landscape; system outputs of water and sediment disperse through the mouth of the river into a lake or ocean

drainage denisty

primary feature of any drainage basin determined by dividing the total length of all stream channels in the basin by the area of the basin

drainage pattern

arrangement of channels in an area, quite distinctive for they are determined by a combination of regional steepness, variable rock resistance/climate/hydrology, relief of the land and structural controls imposed by underlying rocks

dendritic drainage

most common, a treelike pattern, similar to many natural systems (capillaries in humans, patterns in leaves); energy expended by this drainage system is efficient because the overall length of the branches is minimized

trellis drainage

pattern is characteristic of dipping/folded topography; exists in the nearly parallel mountain folds of the ridge and valley province in E. US

how are drainage patterns influenced

• Drainage patterns are influenced by rock structures of variable resistance and folded strata; parallel folded structures direct the principal streams, whereas smaller dendritic tributary streams are at work on nearby slopes

radial drainage

pattern results when streams flow off a central peak/dome, such as occurs on a volcanic mountain


formed by a faulted and jointed landscape which directs stream courses in patterns of right angle turns

parallel drainage

associated with steep slopes


produced by structural domes with concentric patterns of rock strata guiding stream courses


occurs in areas with disrupted surface patterns (glaciated sheild regions of canada) no clear geometry in the drainage and no true stream valley pattern

stream water; potential energy to kinetic

• A mass of water positioned above base level in a stream has potential energy; as water flows downslope or downstream, under the influence of gravity the energy becomes kinetic; the rate of the conversion from pot. To kin. Energy depends on the steepness of the stream channel and volume of water involved


streamsvolume of flow per unit of time, is dependent upon stream channel width anddepth and on the velocity of the flow?


• Q- discharge; w- channel width; d- channel depth; v- stream velocity

• Q increases in a downstream direction with inflow from tributaries, some combination of channel width/depth and stream velocity must also increase• Greater discharge increases the velocity and therefore the capacity of the river to transport sediment as the flood progresses


streams ability to move particles of a specific size is a function of stream velocity and energy available to suspend materials


total possible load that a stream can transport; 4 processes transport eroded materials: solution, suspension, saltation and traction


dissolved load of a stream, esp. the chemical solution derived from minerals such as limestone/dolomite/soluble salts

suspended load

consist of fine grained, clastic particles (bits/pieces of rock); they are held aloft in the stream with the fines particles not deposited until the stream velocity slows nearly to 0


coarser materials that are dragged, roller or pushed along the stream bed by traction or saltation


referring to the way particles bounce along in short hops and jumps; particles that move in this way are too large to remain in suspension but not limited to sliding and rolling

braided stream

maze of interconnected channels which often occurs when reduced discharge lowers a streams transporting ability such as after flooding, commonly occur in glacial environments

where are the greatest and lowest velocities in a stream?

• Greatest velocities in a stream are near the surface at a center channel corresponding to the deepest part of the stream channel• Velocities decrease closer to the sides and bottom of the channel because of frictional drag on the water flow

undercut bank

in streams a steep bank formed along the outer portion of a meandering stream; produced by lateral erosive action of a stream; sometimes called a cutbank

point bar

a deposit of the inner portion of a meander that experiences the slowest water velocity and thus receives sediment fill

oxbow lake

· when former meander becomes isolated from therest of the river that may gradually fill with organic debris and silt or mayagain become part of the river when it floods


degree of inclination; or decline in elevation from its headwaters to its mouth

graded stream

an idealized condition in which a streams load and the landscape mutually adjust; forms a dynamic equilibrium among erosion, transported load, deposition and streams capacity

dynamic eqilibrium

when channels adjust their slope size and shape so that a stream has just enough energy to transport its sediment load


when the longitudinal profile of a stream shows an abrupt change in gradient or a point of interruption (water fall or area of rapids); can result when a stream flows across a zone of hard, resistant rock or from various tectonic uplift episodes• Temporary blockage in a channel caused by a landslide or logjam can also be considered a nickpoint

flood plain

flat, low lying area flanking many stream channels that is subjected to recurrent flooding; formed when river overflows its channel during times of high flow


level of nearly level depositional plain that forms at the mouth of a river


smaller courses divded from channels

birds foot delta

long channel with many distributaries and sediments carried beyond the tip of the delta into the gulf of mexico


high waterflow that overflows the natural bank along any portion of a stream


graph of stream discharge over time for a specific location


work of wind erosion, transportation and deposition

winds ability to move materials

• Ability of wind to move materials is actually small compared with that of other transporting agents such as water and ice bc air is so much less dense than those other media• Over time wind accomplishes enormous work

grain size and wind erosion

intermediate sized grains move most easily (bounce along); largest and smallest sand particles require the strongest winds to move; large particles are heavier and require stronger winds, smaller particles are difficult to move because they exhibit a mutual cohesiveness and usually present a smooth surface to the wind• Finest dust once aloft is carried from continent to continent

wind erosion processes

deflation and abrasion


removal and lifting of individual loose particles; blows away loose or noncohesive sediment and works with rainwater to form a surface resembling a cobblestone street- Desert pavement: protects underlying sediment from further deflation and water erosion- Windblown particles settle between and below coarse rocks and pebbles that are gradually displaced upward- Rainwater is involved as wetting and drying episodes swell and shrink clay sized particles


grinding of rock surfaces by “sand blasting” action of particles captured in the air- Especially effective at polishing exposed rocks when the abrading particles are hard and angular- Variables that affect the rate of abrasion include the hardness of surface rocks, wind velocity and wind consistency- Abrasive action is restricted to the area immediately above the ground no more than a meter or two in height because sand grains are lifted only a short distance- Rocks exposed to eolian abrasion appear pitted, fluted (grooved) or polished


rocks that have evidence of eolian erosion; piece of rock etched and smoothed by eolian erosion


streamline rock structure formed by deflation and abrasion; appears elongated and aligned with the most effective wind direction

what materials can be transported worldwide?

• Atmospheric circulation can transport fine material such as volcanic debris, fire soot and smoke and dust world wide within days

saltation (eolian)

describes wind transportation of grains, usually larger than 0.2mm along the ground• About 80% of wind transport of particles is accomplished by this skipping and bouncing action; executed by aerodynamic lift, elastic bounce and impact

surface creep

grains hit other grains and knock them into the air, saltating particles crash into other particles knocking them both loose and foward


wind sculpted accumulation of sand

3 classifications of dunes

1. Crescentic (crescent/ curve shaped) 2. Linear (straight form) 3. Star dunes


fine grained clays and silts; its binding strength and its internal coherence, loess weathers adn erodes into steep bluffs or vertical faces

alluvial fan

• Fan is produced whenever flowing water abruptly loses velocity as it leaves the constricted channel of the canyon of whenever the stream gradient suddenly decreases and therefore drops layer upon layer of sediment along the base of the mountain block


continuous apron of coalesced alluvial fans, formed along the case of mountains in arid climates, presents a gently rolling surface from fan to fan


unwanted expansion of deserted because the area will no longer sustain agricultural activity once its soils are gone; Occurs due to poor agricultural practices, improper soil moisture management, erosion and salinization, deforestation and global climate change