mass movement

MASS MOVEMENT

SETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSNATURAL TRIGGERS

Earthquakes cause liquefaction

Peru, 1970

MASS MOVEMENT

SETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSNATURAL TRIGGERSVolcanic events induce lahars.

Mt. St. Helens, WA1980

MASS MOVEMENT

SETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSANTRHOPOGENIC TRIGGERSClear-cutting and Forest Fires

MASS MOVEMENT

SETTING OFF A MASS MOVEMENTTRIGGERING MECHANISMSANTRHOPOGENIC TRIGGERSBuilding on Steep Slopes

MASS MOVEMENT

SETTING 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”

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

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.

MASS MOVEMENT

TYPES OF MASS MOVEMENT

SLOW 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

MASS MOVEMENT


SLOW MASS MOVEMENT

SURFACE CREEP

MASS MOVEMENT


SLOW MASS MOVEMENT

SOLIFLUCTION (SOIL FLOW)

Result of movement attributed to freeze-thaw action.Thawed material becomes saturated and can flow.

MASS MOVEMENT


SLOW MASS MOVEMENT

SOLIFLUCTION (SOIL FLOW)

MASS MOVEMENT


RAPID 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.

MASS MOVEMENT


RAPID MASS MOVEMENT

ROCK FALL

Arizona

British Columbia

MASS MOVEMENT


RAPID 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.

MASS MOVEMENT


RAPID MASS MOVEMENT

ROCK SLIDE or LANDSLIDE

Gros Ventre SlideWyoming

1925

MASS MOVEMENT


RAPID 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.

MASS MOVEMENT


RAPID MASS MOVEMENTSLUMPS

MASS MOVEMENT


RAPID MASS MOVEMENT

SLUMPS

CO Rt. 93, Golden, CO

Rt. 36, Boulder, CO

MASS MOVEMENT


RAPID 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.

MASS MOVEMENT



Earthflow - relatively dry during movement.

MASS MOVEMENT



Earthflow

Slumgullion Slide,western CO

700 yBP

MASS MOVEMENT



Mudflow - fine-grained particles mixed with water.

MudflowGuatemala,

1989

MASS MOVEMENT



Quick Clay slide, Rockland, Maine, April 24, 1996

Quick Clay - ground vibrations liquefy sediments.

MASS MOVEMENT



Debris Flow - contains coarser than sand-sizedparticles.

Occurs with a sudden introduction of water.

MASS MOVEMENT



Debris Flow

Revelstoke, BC,Canada

MASS MOVEMENT

PREDICTION OF MASS MOVEMENT

Study 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.

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

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.

STREAMS AND FLOODS

HYDROLOGIC CYCLE

Consider only the surface water component in this chapter.

STREAMS AND FLOODS

STREAMSA stream is any surface water whose flow is confined to

a channel.Stream and river should be used interchangeably.

STREAMS AND FLOODS

FLOODPLAINA floodplain is any flat land immediately surrounding a

stream channel.Floodplains would be submerged if stream overspilled

its banks.

STREAMS AND FLOODS

DRAINAGE BASINThe drainage basin of a stream is the water-collecting

area of a stream.

STREAMS AND FLOODS

TRIBUTARIESTributaries are any smaller streams that feed larger

streams within a drainage basin.

STREAMS AND FLOODS

DRAINAGE DIVIDEA drainage divide is an area

of high topography thatseparates drainage basins (Rocky Mountains).

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.

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

STREAMS AND FLOODS

STREAM FLOW AND DISCHARGE

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.

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.

STREAMS AND FLOODS


Ultimate Base Level Mississippi Delta, LA

Local Base Level Yosemite Falls, CA

STREAMS AND FLOODS


Streams can respond to changes in sea level.Erode rapidly downward when sea level falls.Deposit rapidly when sea level rises.

STREAMS AND FLOODS


AGGRADATION occurs when deposition is greaterthan erosion.

GRADED STREAMS

Aggradation of the Rivière des Ha! Ha! in Quebec

STREAMS AND FLOODS


DEGRADATION occurs when erosion is greaterthan deposition.

GRADED STREAMS

Broadstreet HollowStream, NY

STREAMS AND FLOODS

CHANNEL PATTERNS

STRAIGHT CHANNELS

Channels are dominated by fractures, faults and joints.

STREAMS AND FLOODS

CHANNEL PATTERNS

BRAIDED CHANNELS

Converging and diverging stream channels separatedby sand and gravel bars.

Usually occur in aggrading streams.Deposit most of their sediment in channel beds.

STREAMS AND FLOODS

CHANNEL PATTERNS

BRAIDED CHANNELS

STREAMS AND FLOODS

CHANNEL PATTERNS

MEANDERING 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.

STREAMS AND FLOODS

CHANNEL PATTERNS

MEANDERING CHANNELS

Point Bars

Cut Banks

STREAMS AND FLOODS

WATERFALLS

Occur where barriers to down-cutting exist.Usually only last as long as the barrier exists.

STREAMS AND FLOODS

WATERFALLS

May develop a PLUNGE POOL at the base.

Lower Yellowstone Falls, WYCourtesy of Lindsay Masters

SHORES AND COASTAL PROCESSES

Very dynamic settings.Affected by tides, waves and nearshore currents.Change can be rapid and dramatic.


The COAST is the entire region bordering a body ofwater.

A SHORELINE is the precise border where a body ofwater meets adjacent dry land.


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


WAVES, CURRENTS AND TIDESWAVES AND CURRENTSWave Nomenclature


WAVES, CURRENTS AND TIDESWAVES AND CURRENTSThe distance that the wind travels over water is called its FETCH.Greater the fetch, the larger the waves.


WAVES, CURRENTS AND TIDESWAVES MOVEMENT


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.



BREAKING 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.



BREAKING WAVES



SWASH



BACKWASH


WAVES, CURRENTS AND TIDESWAVE REFRACTION & COASTAL CURRENTS

Produces LONGSHORE CURRENT.


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.


WAVES, CURRENTS AND TIDESTIDAL BORE

Bay of Fundy, NS and NB,Canada



Hopewell Rocks,New Brunswick,

Canada

Low tide

High tide


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.


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.


EROSIONAL LANDFORMS

WAVE CUT NOTCH


EROSIONAL LANDFORMS

WAVE CUT BENCH


EROSIONAL LANDFORMS

SEA CAVES

Australia

Wisconsin


EROSIONAL LANDFORMS

SEA ARCH Elephant Rock, PEI, Canada

London Bridge, AustraliaCourtesy of Lorraine Beane


EROSIONAL LANDFORMS

SEA STACK Acadia

Percé Rock, Quebec


PROTECTION FROM EROSION

RIP RAPHeaps of large angular to subangular boulders.These boulders are piled along the shoreline to slow

or reduce erosion.


PROTECTION FROM EROSIONSEAWALLS

Structures built parallel to shore to prohibit erosion.


COASTAL TRANSPORT AND DEPOSITION

Most 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.

mass movement

Documents

intact mass

results of mass movement

slide moves

concave slipplane

plane of weakness

beforeturtle mountain

preexisting plane ofweakness

face of turtle mountain