The Process of Erosion and Deposition of Sediments

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The Process of Erosion and Deposition of Sediments
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Erosion and Deposition

• The transportation and relocation of sediments
  weathered from rocks

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Erosion

• The moving of rock material from one place to
  another
• For erosion to occur, three processes must take
  place detachment, lifting of the particles, and
  transport.
• There are at least seven processes that can cause
  erosion.

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Erosion by Wind

• Small sediments can be carried in the air by the
  wind.
• Larger sediments can be rolled along the ground.
• Erosion by abrasion may occur as particles come
  in contact with solid objects.
• Examples sand dunes, desert pavement, loess

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Wind
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Erosion by Water

• Fast moving water has a lot of energy and can
  carry larger pieces of rocks and sediments.
• Slow moving water has less energy and can only
  carry tiny particles of sediment.
• When water loses energy, the sediments settle
  out.
• Water has the ability to move materials over long
  distances.
• Examples canyons, gullies, rills, deltas, splash
  erosion

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Water
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Erosion by Waves

• The relentless pounding of waves causes erosion
  in several ways.
• Grinding of materials brought by the waves
  against the shore. This forms sand. This can take
  over 100 years.
• Action of saltwater on the minerals in the rocks
  causes chemical changes in the rock by dissolving
  the minerals.
• Strong waves carrying sand strikes the base of a
  cliff undercutting or breaking the rock.

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Waves
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Erosion by Gravity

• Downward movement of rock and sediment down a
  slope due to the pull of gravity
• The process is quite slow and almost impossible
  to see until the land mass is no longer able to
  support itself and falls or slides down a slope.
• Examples landslide, slump, mass wasting,
  sinkhole, creep

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Gravitational Erosion
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Erosion by Glacial Ice

• Ice moves and carries rocks, grinding the rocks
  beneath it.
• Plucking happens when materials are picked up by
  the moving ice and pushed along by the glacier.
• During abrasion, smaller rocks act like large
  pieces of sand paper and cause grooves to be
  carved into the land.
• Huge U-shaped valleys are cause by continental
  glaciers.

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Ice
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Erosion by Bioerosion

• Bioerosion is the erosion of ocean rocks by
  living animals.
• This is done by boring, drilling, rasping, or
  scraping.
• Most often done by some mollusks, sponges,
  chiton, urchins, algae, bacteria, and fish

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Bioerosion
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Deposition

• The laying down or dropping off of sediments that
  were carried to a new location from another
  location
• Deposition can be transported by wind, water, or
  ice.

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Deposition by Wind

• Wind can transport material suspended in the air,
  hundreds of km from its original location.
• Heavier materials may be pushed along the ground.
• Material is deposited when the wind changes
  direction or loses its kinetic energy.
• Obstacles, man-made or natural, will often
  determine where the deposition occurs and the
  type of feature formed (Ex dunes, ripples).

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Wind
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Deposition by Water

• Water will carry sediments until the flow slows
  down enough to drop the sediments.
• Larger particles are deposited near the shore.
  Smaller particles settle out farther from the
  shore.
• Deposited materials can be seen in river beds,
  deltas, mud flats, and sand bars.

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Water
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Deposition by Ice

• Melting glaciers leave materials behind.
• Includes huge boulders (erratics), piles of
  smaller rocks (moraines), glacial lakes, clay,
  and sand (till)
• Glacial flows become slower if input is reduced
  or when the ice begins to melt.

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Ice