Mass movements
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Mass Movements. Mass Movements. Mass Movement - The transfer of rock and soil downslope due to gravity.

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Mass Movements

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Mass movements

Mass Movements


Mass movements1

Mass Movements

  • Mass Movement - The transfer of rock and soil downslope due to gravity

http://www.google.com/imgres?sa=X&biw=1242&bih=564&tbm=isch&tbnid=VcH3Ba1hGjgUnM%3A&imgrefurl=http%3A%2F%2Fwww.physicalgeography.net%2Ffundamentals%2F10x.html&docid=nHHnC9GUoREK_M&imgurl=http%3A%2F%2Fwww.physicalgeography.net%2Ffundamentals%2Fimages%2Frockfall.jpg&w=450&h=307&ei=Fq0MU8eEKMiWyAGklYAg&zoom=1&ved=0CGwQhBwwAQ&iact=rc&dur=808&page=1&start=0&ndsp=10

http://www.google.com/imgres?sa=X&biw=1242&bih=564&tbm=isch&tbnid=9v1Vxp8K8tfP5M%3A&imgrefurl=http%3A%2F%2Fwww.onegeology.org%2Fextra%2Fkids%2Fearthprocesses%2FmassMovements.html&docid=BaWI15hTa4h_qM&imgurl=http%3A%2F%2Fwww.onegeology.org%2Fextra%2Fkids%2Fimages%2FriverErosion.jpg&w=500&h=300&ei=Fq0MU8eEKMiWyAGklYAg&zoom=1&ved=0CG8QhBwwAg&iact=rc&dur=251&page=1&start=0&ndsp=10


Triggers of mass movements

Triggers of Mass Movements

  • Gravity is the force behind mass movements.

  • Several factors make slopes more susceptible to the pull of gravity.


Factors that trigger mass movements

Factors that Trigger Mass Movements

  • Saturation of surface materials with water

  • Over steepening of slopes

  • Removal of vegetation

  • Earthquakes


Water as a trigger for mass movement

Water as a Trigger for Mass Movement

  • Heavy rains and rapid snowmelt can saturate surface materials and trigger a mass movement.

  • Example – 1998 Hurricane Mitch produced torrential rains, causing devastating mudflows.

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=wHZgPgHa2qt6OM%3A&imgrefurl=http%3A%2F%2Fsarahi07.blogspot.com%2F2011%2F04%2Fhonduras-background-history.html&docid=Jgt59aPqWqqnvM&imgurl=http%3A%2F%2Fproyectolatinoamerica.wikispaces.com%2Ffile%2Fview%2Fmitchgal1.jpg%2F33869145%2Fmitchgal1.jpg&w=350&h=253&ei=CLEMU9zhHemQyAGswIHYCw&zoom=1&ved=0CIIBEIQcMAk&iact=rc&dur=433&page=1&start=0&ndsp=10


Mass movements

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=cCyCnYzsisz1kM%3A&imgrefurl=http%3A%2F%2Fhurricanemitchinteraction.blogspot.com%2F&docid=yt8DwNdhPnwhAM&imgurl=http%3A%2F%2F4.bp.blogspot.com%2F_clfj3FfKfYo%2FSf72kilFISI%2FAAAAAAAAAB0%2FIeYDjEYLPGY%2Fs320%2Fel%252Bsalvador.bmp&w=318&h=268&ei=CLEMU9zhHemQyAGswIHYCw&zoom=1&ved=0CIgBEIQcMAs&iact=rc&dur=317&page=2&start=10&ndsp=16

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=fPyepA6pFI75fM%3A&imgrefurl=http%3A%2F%2Fbelizeadventure.com%2F2013%2F11%2Fhurricane-mitch%2F&docid=gIHHUqRYvohcAM&imgurl=http%3A%2F%2Fbelizeadventure.com%2Fwp-content%2Fuploads%2F2013%2F11%2FCG-Tegucigalpa-1.jpg&w=900&h=591&ei=CLEMU9zhHemQyAGswIHYCw&zoom=1&ved=0CHwQhBwwBw&iact=rc&dur=320&page=1&start=0&ndsp=10


Water as a trigger for mass movement1

Water as a Trigger for Mass Movement

  • When pores in sediment become filled with water, the particles slide past each other more easily.


Water as a trigger for mass movement2

Water as a Trigger for Mass Movement

  • When sand grains are slightly moist they will stick together, even on a relatively steep slope.

  • If you add enough water however, the pores between the grains will fill with water and the sand-water-mixture will ooze downhill


Over steepened slopes

Over-steepened Slopes

  • Loose soil particles can maintain a relatively stable slope up to a certain angle.

  • The slope angle ranges between 25 and 40 degrees, depending on the size and shape of the particles.

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=SWO5g8KoTOd_rM%3A&imgrefurl=http%3A%2F%2Fblogs.scientificamerican.com%2FWSS%2Fpost.php%3Fblog%3D22%26post%3D156&docid=4TzSl6JgZWP1qM&imgurl=http%3A%2F%2Fblogs.scientificamerican.com%2Fhistory-of-geology%2Ffiles%2F2011%2F07%2FBRESSAN_angle_repose.jpg&w=500&h=468&ei=xbsMU8iCMaiQyAGt8oGIDQ&zoom=1&ved=0CIgCEIQcMDo&iact=rc&dur=190&page=5&start=55&ndsp=15


Over steepened slopes1

Over-steepened Slopes

  • An over-steepened slope is a slope which exceeds the stable angle for the type of material in the location.

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=eQHWc0NsJXvIZM%3A&imgrefurl=http%3A%2F%2Fimnh.isu.edu%2Fdigitalatlas%2Fgeo%2Fbasics%2Fmassmvnt.htm&docid=H50w3C-07S7s2M&imgurl=http%3A%2F%2Fimnh.isu.edu%2Fdigitalatlas%2Fgeo%2Fbasics%2Fimgs%2Fdiagram.gif&w=399&h=244&ei=_b8MU8SdIumkyQHqs4HoDA&zoom=1&ved=0CJQCEIQcMD4&iact=rc&dur=454&page=5&start=60&ndsp=14


Over steepened slopes2

Over-steepened Slopes

  • An over-steepened slope can result when a stream undercuts a valley wall or waves pound against the base of a cliff.

  • People can create over-steepened slopes during excavation for roads or other structures

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=TFrHAp6GUrNGbM%3A&imgrefurl=http%3A%2F%2Fwww.tulane.edu%2F~sanelson%2Fgeol204%2Fslopestability.htm&docid=tOuWwjrehUOctM&imgurl=http%3A%2F%2Fwww.tulane.edu%2F~sanelson%2Fimages%2FHwycut2.jpg&w=265&h=209&ei=_b8MU8SdIumkyQHqs4HoDA&zoom=1&ved=0CG0QhBwwCQ&iact=rc&dur=360&page=1&start=0&ndsp=15


Removal of vegetation

Removal of Vegetation

  • Plants make slopes more stable because their root systems bind soil and regolith together.

  • When plants are removed by forest fires or human activities such as logging or farming, the likelihood of mass movement increases.

http://www.google.com/imgres?hl=en&biw=1242&bih=564&tbm=isch&tbnid=s5crKvG6o17LWM%3A&imgrefurl=http%3A%2F%2Fwww.npr.org%2Fblogs%2Fparallels%2F2013%2F05%2F31%2F187301981%2FBattling-Deforestation-In-Indonesia-One-Firm-At-A-Time&docid=dKWDKrQKsJbyEM&imgurl=http%3A%2F%2Fmedia.npr.org%2Fassets%2Fimg%2F2013%2F05%2F30%2Fsumatra_deforestation1_custom-39040cba07f740c9627ec3f75c5fd0982029db73.jpg&w=4256&h=2832&ei=hsIMU9iYCsepyAHNo4DQCg&zoom=1&ved=0CIUBEIQcMAo&iact=rc&dur=400&page=2&start=8&ndsp=13


Removal of vegetation1

Removal of Vegetation

  • In Menton France, farmers replaced olive trees, which have deep roots, with carnations, a more profitable but shallow rooted crop.

  • Planting the carnations made the slopes less stable.

  • A landslide on one of the slopes killed 11 people

http://www.google.com/imgres?sa=X&hl=en&biw=1242&bih=564&tbm=isch&tbnid=WqOY3v9BcWhNVM%3A&imgrefurl=http%3A%2F%2Fxenophilius.wordpress.com%2F2009%2F10%2F14%2F&docid=veb-93oJanJSaM&imgurl=http%3A%2F%2Fi2.cdn.turner.com%2Fcnn%2F%2Fvideo%2Fweather%2F2009%2F10%2F13%2Fvon.wa.landslide.aerials.komo.576x324.jpg&w=576&h=324&ei=C8MMU8iCJPOLyQGWm4E4&zoom=1&ved=0CGEQhBwwBQ&iact=rc&dur=298&page=1&start=0&ndsp=15


Earthquakes

Earthquakes

  • Earthquakes are one of the most dramatic triggers of mass movements.

  • An earthquake and its aftershocks can dislodge enormous amounts of rock and soil.

  • The landslide in the

    picture was triggered by

    an earthquake


Types of mass movements

Types of Mass Movements

  • Geologists classify mass movements based on the kind of material that moves, how it moves, and the speed of the movement.

  • There are 5 main types of mass movement

    Rockfalls, slides, slumps, flows, and creep


Rockfalls

Rockfalls

  • A rockfall occurs when rocks or rock fragments fall freely through the air.

  • This type of mass movement is common on slopes that are too steep for loose material to remain on the surface.

http://www.google.com/imgres?sa=X&hl=en&biw=1242&bih=564&tbm=isch&tbnid=j3drk6LnBQtCCM%3A&imgrefurl=http%3A%2F%2Fgeology.campus.ad.csulb.edu%2Fpeople%2Fbperry%2FMass%2520Wasting%2FFalls.htm&docid=Fk6UWTXrfaXLWM&imgurl=http%3A%2F%2Fgeology.campus.ad.csulb.edu%2Fpeople%2Fbperry%2FMass%252520Wasting%2FRockAvalancheDiagramFallS.GIF&w=354&h=253&ei=tNQMU4uZNaiCyQHqpoEQ&zoom=1&ved=0CI0BEIQcMAw&iact=rc&dur=279&page=2&start=10&ndsp=17


Rockfalls1

Rockfalls

  • Many rockfalls result from the mechanical weathering of rock caused by freeze-thaw cycles or plant roots.

  • Rockfalls sometimes trigger other mass movements.


Slides

Slides

  • In a slide, a block of material moves suddenly along a flat, inclined surface.

  • Slides that include segments of bedrock are called rockslides.


Rockslides

Rockslides

  • Rockslides are among the fastest mass movements, reaching speeds of over 200 km per hour.

Click for Rockslide Video


Slumps

Slumps

  • A slump is the downward movement of a block of material along a curved surface.

  • The material in a slump usually does not travel very fast or very far.

  • As the block moves, its upper surface sometimes tilts backward.


Slumps1

Slumps

  • Slumps leave a crescent-shaped cliff just above the slump, which you can see in the picture.

  • They are common on oversteepened slopes where the soil contains thick accumulations of clay.


Flows

Flows

  • Flows are mass movements of material containing a large amount of water, which move downslope as a thick fluid.

  • Flows that move quickly, called mudflows, are common in semiarid mountainous regions, such as parts of southern California.

http://www.google.com/imgres?start=93&biw=1242&bih=564&tbm=isch&tbnid=t0SIVOhvQdCXrM%3A&imgrefurl=http%3A%2F%2Fwww.mvequinox.net%2F2011%2F12%2Fadventures-ahoy.html&docid=tfa35gTSDtkJGM&imgurl=http%3A%2F%2F1.bp.blogspot.com%2F-LimTeNGC2h8%2FTuLHisGjfaI%2FAAAAAAAACuA%2FNYlpIIOtUP0%2Fs1600%2FDSC01102.JPG&w=800&h=600&ei=Q90MU7SED-eayAHM14D4Cw&zoom=1&ved=0CBUQhBwwBDhk&iact=rc&dur=193&page=8&ndsp=16


Mudflows

Mudflows

  • In these regions, protective vegetation is sparse. A heavy downpour or rapid snowmelt can flood canyons with a mixture of soil, rock, and water.

  • The mixture may have the consistency of wet concrete.


Mudflows1

Mudflows

  • It follows the contours of the canyon, taking large boulders and trees along with it.

  • As you see in the photo, mudflows in populated areas are very dangerous and destructive.

    Click photo for mudflow video


Earthflows

Earthflows

  • Earthflows are flows that move relatively slowly—from about a millimeter per day to several meters per day.

  • Their movement may continue for years.

  • Earthflows occur most often on hillsides in wet regions.


Earthflows1

Earthflows

  • When water saturates the soil on a hillside, the material breaks away, forming a tongue-shaped mass like the one shown


Creep

Creep

  • The slowest type of mass movement is creep, which usually only travels a few millimeters or centimeters per year.

  • One factor that contributes to creep is alternating between freezing and thawing

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=BiCGnUaxouhl5M&tbnid=pdzHjgTkhNnjbM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.geogrify.net%2FGEO1%2FLectures%2FWeathering%2FMassWasting.html&ei=VOkMU_jcBYigrQGr4YHIDA&psig=AFQjCNEPNTuYl_Uz6CDf3LlV2FxvefWW2g&ust=1393441267515600


Creep1

Creep

  • Because creep is so slow, you cannot observe it directly.

  • You can recognize the effects of creep easily however – creep causes structures that were once vertical to tilt downhill.

http://courses.missouristate.edu/EMantei/creative/WeathStrem/creep.jpg


Click photo for landslides videos

Click Photo for Landslides Videos

http://www.google.com/imgres?biw=1242&bih=564&tbm=isch&tbnid=BAmPBXiDDcL_TM%3A&imgrefurl=http%3A%2F%2Fgallery.usgs.gov%2Fphotos%2F03_08_2010_bFVi0MLyx6_03_08_2010_12&docid=R28pxRp5Jj5T7M&imgurl=http%3A%2F%2Fgallery.usgs.gov%2Fimages%2F03_08_2010%2FbFVi0MLyx6_03_08_2010%2Fmedium%2Flandslide.jpg&w=500&h=333&ei=XusMU72BDeblyQGqsIHwDA&zoom=1&ved=0CNsBEIQcMCQ&iact=rc&dur=503&page=3&start=25&ndsp=15


Mass movements

VideosMudflow- https://www.youtube.com/watch?v=MM1TTzARW94Creep- http://www.youtube.com/watch?v=l1jqDLiQXbsRockslide= http://www.youtube.com/watch?v=ZVYGJYnJTi0Landslide=http://www.youtube.com/watch?v=K5pidzTZslohttps://www.youtube.com/watch?v=Z02coWd2ixI


References

References

  • Adapted from Prentice Hall Earth Science Text at http://mhs.wcpss.net/teachers/murphy/earthscience/textbook/este053.pdf


Picture of the day

Picture of the day!!!!

  • http://epod.usra.edu/


Mass movements

Earth & Space Science

Today’s Schedule

September 16, 2014

5 min-Bell ringer

30 min- Mass Wasting Notes and Videos

25 min Erosion & Deposition definitions (cause & effect), examples matching review

10 Exit – HASHTAG VOTES

Essential Question

What are different types of deposition?

Vocabulary

*Creep *Mudflow *Earthflow *Rockslide

*Landslide

Today we will…….

ES.1.18 - Demonstrate the possible effects of atmospheric changes brought on by things such as acid rain,

ES.1.26ES.1.26 - Differentiate among the processes of weathering, erosion, transportation of materials, deposition, and soil formation.

ES.1.27ES.1.27 - Illustrate the various processes that are involved in the rock cycle and discuss how the total amount of material stays the same through formation, weathering, sedimentation, and reformation.


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