Erosion and Mass Wasting

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Erosion and Mass Wasting

• What is erosion?
• General processes whereby earth materials are
  loosened, dissolved, worn awayremoved from one
  place to be added to another.
• Processes involved.
• Hydraulic impact
• Corrosion
• Corrasion
• Tillage
• Frost

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Hydraulic Impact
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Corrosion
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Corrasion
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Tillage
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Frost
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Erosion and Mass Wasting

• What is mass wasting?
• Erosion on a massive scale

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Erosion and Mass Wasting

• Why use aerial photographs?
• Hazard detection/warning
• Clues to soil behavior, climate events
• The vertical perspective allows forms to be seen
  in their entirety
• Predict behavior under new land uses

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Erosion and Mass Wasting

• General procedural goal for aerial photos.
• Learn to recognize fresh forms, then old forms
  that are covered by vegetation.

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Erosion

• Erosion features observable from aerial
  photographs
• Drainage channelsrills, gullies, streams
• Cross sections and plan views
• See Keser, p.27, table 2

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Erosion

• Observable from aerial photographs
• Slope forms
• Straight
• Concave
• Convex

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Erosion

• Observable from aerial photographs
• Tone changes across bare soil areas-exposed B and
  C horizons

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Erosion

• Erosion control patternsclues to predicting soil
  properties and behavior.
• Contour cropping
• Terraces
• Sediment ponds
• Dammed impoundments

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Terraces
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Sediment Ponds
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Mass Wasting

• Mass wasting forms
• observable from aerial
• photographs
• Falls-transported by
• gravity without water
• talus, rock fall, rock streams

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Mass Wasting

• Slumps-shear failure on concave face with block
  movement of soil and underlying strata. Block may
  not be deformed.

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Mass Wasting

• Earth flowshear failure and movement of upper
  soil layers. Soil behaves like liquid.

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Mass Wasting

• Debris flowsmaterial behaves like a liquid,
  flows out of channels.