mass movement
DESCRIPTION
MASS MOVEMENT. SETTING OFF A MASS MOVEMENT. TRIGGERING MECHANISMS. NATURAL TRIGGERS. Earthquakes cause liquefaction. Peru, 1970. MASS MOVEMENT. SETTING OFF A MASS MOVEMENT. TRIGGERING MECHANISMS. NATURAL TRIGGERS. Volcanic events induce lahars. Mt. St. Helens, WA 1980. MASS MOVEMENT. - PowerPoint PPT PresentationTRANSCRIPT
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MASS MOVEMENTSETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSNATURAL TRIGGERS
Earthquakes cause liquefaction
Peru, 1970
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MASS MOVEMENTSETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSNATURAL TRIGGERSVolcanic events induce lahars.
Mt. St. Helens, WA1980
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MASS MOVEMENTSETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSANTRHOPOGENIC TRIGGERSClear-cutting and Forest Fires
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MASS MOVEMENTSETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSANTRHOPOGENIC TRIGGERSBuilding on Steep Slopes
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MASS MOVEMENTSETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSANTRHOPOGENIC TRIGGERSMining In April 29th, 1903 a disastrous landslide took place at Frank, Alberta.
A huge slab of limestone slid from the face of Turtle Mountain and wiped out part of the town.
Before
Turtle Mountain or “Mountain That Walks”
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100 seconds later, it was all over.
Survivors described a cracking sound like cannon fire echoing throughout the mountains.
A 640 metre high, 915 metre wide, 152 metre thick (2,100 feet by 3,000 feet by 500 feet) wedge of the eastern slope of Turtle Mountain gave way and slid 700 metres (2,300 feet) down the mountain side. An estimated 182,000,000,000,000 kg (one hundred million tons) of limestone slid into the valley and onto the town of Frank.
After
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MASS MOVEMENT
All mass movements are influenced by weatheringand erosion, water, tectonics and biology.
Results of mass movement stem from interactionbetween lithosphere, biosphere, atmosphereand hydrosphere.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTSLOW MASS MOVEMENT
Slowest form of mass movement.Gradual downslope movement of unconsolidated
material.Invokes only upper few meters of sediment.Moves faster at the surface than at depth.
SURFACE CREEP
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MASS MOVEMENT
TYPES OF MASS MOVEMENTSLOW MASS MOVEMENT
SURFACE CREEP
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MASS MOVEMENT
TYPES OF MASS MOVEMENTSLOW MASS MOVEMENT
SOLIFLUCTION (SOIL FLOW)
Result of movement attributed to freeze-thaw action.Thawed material becomes saturated and can flow.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTSLOW MASS MOVEMENT
SOLIFLUCTION (SOIL FLOW)
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
ROCK FALL
Fastest type of rapid mass movement.Particles fall from steep slope.
Particles move at rates of km/hr or m/sec.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
ROCK FALL
Arizona
British Columbia
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
ROCK SLIDE or LANDSLIDE
Occurs when rock, sediment, or unconsolidated material breaks loose and moves in contact withunderlying slope along a pre-existing plane ofweakness such as a fault, fracture or beddingplane.
Plane of weakness is called a SLIP-PLANE.SLIP-PLANE is usually flat or planar.Slide moves in a single, intact mass.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
ROCK SLIDE or LANDSLIDE
Gros Ventre SlideWyoming
1925
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
ROCK SLIDE or LANDSLIDE
Gros Ventre SlideWyoming
1925
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
SLUMPS
A slide that occurs on a curved or concave slip-plane moving in a downward and outward motion.
Slumps create their own slip-plane.Usually have a crescent-shape scar at top of slope.Steep slope at the top of the scar is called a scarp.End of the slump is called the toe.Slumps don’t usually travel far.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTSLUMPS
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENT
SLUMPS
CO Rt. 93, Golden, CO
Rt. 36, Boulder, CO
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Occurs when a mixture of rock fragments, soil and/orsediment moves downslope as a highly viscousfluid.
Flows move rapidly.Dangerous when they have a high water content.Can be related to rainfall.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Earthflow - relatively dry during movement.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Earthflow
Slumgullion Slide,western CO
700 yBP
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Mudflow - fine-grained particles mixed with water.
MudflowGuatemala,
1989
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Quick Clay slide, Rockland, Maine, April 24, 1996Quick Clay - ground vibrations liquefy sediments.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Debris Flow - contains coarser than sand-sizedparticles.
Occurs with a sudden introduction of water.
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MASS MOVEMENT
TYPES OF MASS MOVEMENTRAPID MASS MOVEMENTFLOWS
Debris Flow
Revelstoke, BC,Canada
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MASS MOVEMENT
PREDICTION OF MASS MOVEMENTStudy local geology.Consider local historical record.Determine if patterns of mass movement exist.
Use 14C, cosmogenic dating, lichenometry,and dendrochronology of older massmovements.
Consider animal behavior.
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MASS MOVEMENT
AVOIDANCE OF MASS MOVEMENT
Avoid slide prone areas.Look for signs of historical mass movement.
Bent treesCracks in slopeCuts at base of slopeTilted utility polesUnusually low house pricesCheck out the neighborhoodRead the local newspaper before buying
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STREAMS AND FLOODS
WATER DISTRIBUTION ON EARTH
The amount of water in, on, and above Earth isapproximately 1.36 billion cubic kilometers.
This amount has been fairly constant over past 1 by.
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STREAMS AND FLOODS
HYDROLOGIC CYCLE
Consider only the surface water component in this chapter.
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STREAMS AND FLOODS
STREAMSA stream is any surface water whose flow is confined to
a channel.Stream and river should be used interchangeably.
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STREAMS AND FLOODS
FLOODPLAINA floodplain is any flat land immediately surrounding a
stream channel.Floodplains would be submerged if stream overspilled
its banks.
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STREAMS AND FLOODS
DRAINAGE BASINThe drainage basin of a stream is the water-collecting
area of a stream.
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STREAMS AND FLOODS
TRIBUTARIESTributaries are any smaller streams that feed larger
streams within a drainage basin.
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STREAMS AND FLOODS
DRAINAGE DIVIDEA drainage divide is an area
of high topography thatseparates drainage basins (Rocky Mountains).
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STREAMS AND FLOODS
STREAM FLOW AND DISCHARGEFlow of any stream is driven by its gradient.GRADIENT is the vertical drop over the course of a
stream.Gradient depends upon topography.
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STREAMS AND FLOODS
STREAM FLOW AND DISCHARGEDISCHARGE is the volume of water passing a given
point in a given amount of time.
Q = D x W x V
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STREAMS AND FLOODSSTREAM FLOW AND DISCHARGE
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STREAMS AND FLOODS
STREAM FLOW AND DISCHARGE
Mississippi River discharge = 18,000 cms (600,000 cfs)
Amazon RiverDrains area 75% smaller than U.S.Discharge = 200,000 cms (7,000,000 cfs)= 1/5 of the Earth’s freshwater flow1 day’s discharge from the Amazon would
supply NYC with fresh water for 5 YEARS.
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STREAMS AND FLOODS
GEOLOGIC WORK OF STREAMS
Streams are responsible for erosion and deposition ofsediment.
Streams cut through uplifted land toward base level.BASE LEVEL is the lowest level to which a stream can
erode its channel.Ultimate base level is sea level.Local base levels can occur.
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STREAMS AND FLOODS
GEOLOGIC WORK OF STREAMS
Ultimate Base Level Mississippi Delta, LA
Local Base Level Yosemite Falls, CA
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STREAMS AND FLOODS
GEOLOGIC WORK OF STREAMS
Streams can respond to changes in sea level.Erode rapidly downward when sea level falls.Deposit rapidly when sea level rises.
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STREAMS AND FLOODS
GEOLOGIC WORK OF STREAMS
AGGRADATION occurs when deposition is greaterthan erosion.
GRADED STREAMS
Aggradation of the Rivière des Ha! Ha! in Quebec
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STREAMS AND FLOODS
GEOLOGIC WORK OF STREAMS
DEGRADATION occurs when erosion is greaterthan deposition.
GRADED STREAMS
Broadstreet HollowStream, NY
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STREAMS AND FLOODS
CHANNEL PATTERNSSTRAIGHT CHANNELSChannels are dominated by fractures, faults and joints.
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STREAMS AND FLOODS
CHANNEL PATTERNSBRAIDED CHANNELSConverging and diverging stream channels separated
by sand and gravel bars.Usually occur in aggrading streams.Deposit most of their sediment in channel beds.
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STREAMS AND FLOODS
CHANNEL PATTERNSBRAIDED CHANNELS
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STREAMS AND FLOODS
CHANNEL PATTERNSMEANDERING CHANNELSStreams wind across relatively flat landscape.Loops or MEANDERS form as stream erodes its
banks.Erosion takes place on the CUT BANK, which is the
outside loop of the meander.Deposition takes place on the POINT BAR, which is
on the inside loop of the meander.
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STREAMS AND FLOODS
CHANNEL PATTERNSMEANDERING CHANNELS
Point Bars
Cut Banks
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STREAMS AND FLOODS
WATERFALLS
Occur where barriers to down-cutting exist.Usually only last as long as the barrier exists.
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STREAMS AND FLOODS
WATERFALLSMay develop a PLUNGE POOL at the base.
Lower Yellowstone Falls, WYCourtesy of Lindsay Masters
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SHORES AND COASTAL PROCESSES
Very dynamic settings.Affected by tides, waves and nearshore currents.Change can be rapid and dramatic.
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SHORES AND COASTAL PROCESSES
The COAST is the entire region bordering a body ofwater.
A SHORELINE is the precise border where a body ofwater meets adjacent dry land.
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SHORES AND COASTAL PROCESSES
Waves are produced as air flows from high pressure areas to low pressure areas.
Air moves across water surface and with friction reshapes water surface into waves.
Velocity of 3 km/hr (2 mph) is all that is needed to generate waves.
WAVES, CURRENTS AND TIDESWAVES AND CURRENTS
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES AND CURRENTS
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES AND CURRENTSWave Nomenclature
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES AND CURRENTSThe distance that the wind travels over water is called its FETCH.Greater the fetch, the larger the waves.
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES AND CURRENTS
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENT
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENTWave form moves horizontally, water particles do not.Water particles move in a circular orbit.Called OSCILLATORY MOTION.This motion disappears below WAVE BASE.Wave base = 1/2 the wavelength.Water below wave base is generally undisturbed.
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENT
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENTBREAKING WAVES
As waves touch bottom, velocity decreases.Wavelength decreases, wave height increases.Waves bunch up and steepenWave crests move faster than troughs.Crest overruns the wave and BREAKS.Motion changes from oscillatory to translatory.Water moving forward on the beach becomes SURF.
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENTBREAKING WAVES
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENT
SWASH
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVES MOVEMENT
BACKWASH
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESWAVE REFRACTION & COASTAL CURRENTS
Produces LONGSHORE CURRENT.
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESTIDES
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESTIDES
Rising tide is called FLOOD TIDE.
Under right geologic and geographic conditions canproduce TIDAL BORE.
Lowering or falling tide is called EBB TIDE.
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESTIDAL BORE
Bay of Fundy, NS and NB,Canada
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SHORES AND COASTAL PROCESSES
WAVES, CURRENTS AND TIDESTIDES Hopewell Rocks,
New Brunswick,Canada
Low tide
High tide
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SHORES AND COASTAL PROCESSES
COASTAL EROSION
Due to the concentration of wave energy on shorelinesand coasts.
~14,000 waves hit exposed rock or beaches every day.Erosion is caused by the forcing of water and air
under high pressure into small crevices.Once rock is broken up, pieces are abraded against
the coast.
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SHORES AND COASTAL PROCESSES
COASTAL EROSION
Coastal erosion is driven by:
Wave size and energyErodibility of local rocksSlope of the sea floor
Gentle slope, waves break offshoreSteep slope, wave break close to shoreCommon in headland areas.
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SHORES AND COASTAL PROCESSES
EROSIONAL LANDFORMS
WAVE CUT NOTCH
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SHORES AND COASTAL PROCESSES
EROSIONAL LANDFORMS
WAVE CUT BENCH
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SHORES AND COASTAL PROCESSES
EROSIONAL LANDFORMS
SEA CAVES
Australia
Wisconsin
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SHORES AND COASTAL PROCESSES
EROSIONAL LANDFORMS
SEA ARCH Elephant Rock, PEI, Canada
London Bridge, AustraliaCourtesy of Lorraine Beane
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SHORES AND COASTAL PROCESSES
EROSIONAL LANDFORMS
SEA STACK Acadia
Percé Rock, Quebec
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SHORES AND COASTAL PROCESSES
PROTECTION FROM EROSIONRIP RAPHeaps of large angular to subangular boulders.These boulders are piled along the shoreline to slow
or reduce erosion.
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SHORES AND COASTAL PROCESSES
PROTECTION FROM EROSIONSEAWALLS
Structures built parallel to shore to prohibit erosion.
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SHORES AND COASTAL PROCESSES
COASTAL TRANSPORT AND DEPOSITIONMost commonly produces a feature known as a BEACH.A BEACH is a dynamic, relatively narrow segment of
coast washed by waves and tides and covered withsediments of various sizes and composition.
DUNES can develop at the back of a beach.DUNES are long ridges of sand formed by wind blowing
sand from the front of the beach to the back of the beach.