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Mass wastage

Mass wastage. Part One. What exactly do we mean when we say “ mass wastage ”?. Mass wastage = Mass wasting = Mass movement It is the down slope movement of weathered materials (rock , regolith, and soil) under the direct influence of gravity

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Mass wastage

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  1. Mass wastage Part One

  2. What exactly do we mean when we say “mass wastage”? • Mass wastage = Mass wasting = Mass movement • It is the down slope movement of weathered materials (rock, regolith, and soil) under the direct influence of gravity • It can be slow, or rapid, suddenand catastrophic

  3. Gravity • The effectiveness of gravity is determined by the steepness of the slope and thickness of loose materials • In other words, steeper landscape = greater force to move objects downslope • Greater the thickness of moving mass = greater speed

  4. Causes of mass wasting1) Natural: Expansion of soil • Expanding and contracting of soil • Water gets into soil  soil gets heavier  expansion makes soil move slightly  instability!

  5. Causes of mass wasting2) Logging practices • Clear-cuttingtrees (most or all trees in an area are uniformly cut down) leaves a slope with little vegetation stability • Logging roads cut deeply into mountain sides

  6. Causes of mass wasting3) Urbanization • Removed vegetation and alterednatural drainage patterns  creates flash floods

  7. Methods of stabilizing slopes1) Vegetation • Plant roots can help to anchor the soil • Leaves and roots can help protect the soil from being washed away by heavy rains

  8. Methods of stabilizing slopes… on Highways! • Bolts (See textbook diagram on page 37)

  9. Concrete spray People working on the Sea to Sky construction project

  10. Wire mesh

  11. Drainage pipes and Retaining walls • (See textbook diagram on page 37)

  12. Terracing

  13. Snowsheds • (See textbook diagram on page 37)

  14. Tunnels

  15. Types of Mass Wasting:1) Scree/ talus • On very steep slopes, soils do not have the chance to form and blocks of rock become loosened • Frost shatter causes the regolith to loosen and tumble down • Blocks are mostly large and sharp-edged and so do not travel far • They build a pile of loose rocks at the bottom calledscreeor talus

  16. Types of Mass Wasting:2) Soil Creep • Slow, almost imperceptible downhill motion of soil particles • Common in humid areas • Helped by soil expansion and contracting • Most common

  17. Types of Mass Wasting:3) Landslide • Rapid movement of soil down slope • Rock is weathered into soil • Heavy rainfall often triggers it • Freeze-thaw action

  18. http://www.youtube.com/watch?v=f19Onak6KC0

  19. Types of Mass Wasting:4) Mudflow • Soil absorbs so much water that it literally flows downhill • Everything in it mixes thoroughly

  20. http://www.youtube.com/watch?v=8mKC3eID074&feature=related http://www.youtube.com/watch?v=SrYqJlCuppA&feature=related

  21. Types of Mass Wasting:5) Slump • A slab of land breaks away and slips a short distance • See page 38 for a lovely diagram!

  22. Types of Mass Wasting:6) Avalanche • A mass of snow and ice that breaks away and slides down a slope • Heavy accumulation of snow • Air temperatures make them unstable • Can be very dangerous

  23. http://www.youtube.com/watch?v=bJ0osmXOfvs&feature=related

  24. Types of Mass Wasting:7) Soil Solution • Soil materials transported by water • Very small particles in seeming less transparent water

  25. TIME FOR REVIEW!!!

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