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Weathering

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Once a rock has been broken down by weathering, rock particles and soil can be moved by ... *plants can be both physical and chemical weathering Erosion The carrying ... – PowerPoint PPT presentation

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Title: Weathering


1
Weathering
  • All of the processes that break rock into smaller
    pieces
  • Rocks can be weathered only when they are exposed
    to the earths surface.

2
There are 2 types of weathering
  • Physical The ways in which rock breaks down
    into smaller pieces without any chemical change
    in the materials of the rock.
  • Also known as MECHANICAL
  • Examples of physical weathering include
  • a. Frost action water enters cracks in rock
    freezes.
  • b. Root action roots work their way into
    rocks (plants can do this).
  • c. Thermal expansion heating and cooling
    (wind)
  • d. Abrasion rocks come in contact with other
    rocks.

3
  • Chemical the ways in which rock breaks down by
    chemically changing some of the materials in the
    rock.
  • takes place best in hot, wet climates.
  • Agents of chemical weathering include
  • a. Water
  • b. Oxygen (rusting by oxidation)
  • c. Carbon dioxide (carbon dioxide water
    acid
  • d. Living organisms (lichens fungi algae)
  • plants can be both physical and chemical
    weathering

4
Erosion
  • The carrying away of weathered material.
  • Once a rock has been broken down by weathering,
    rock particles and soil can be moved by several
    means. These include gravity, streams,
    ice/glaciers, wind, or waves.

5
  • Types of Erosion
  • Erosion by Gravity
  • Pulls pieces of rock to the bottom of a slope.
  • This type of erosion causes landslides, creep,
    and slump
  • Erosion by Streams
  • Happens one of 2 ways.
  • 1. soil and rock are carried away, and water
    does not change the rock.
  • 2. when particles are carried away by the
    waters current, they wear away the channel
    through which the stream flows.
  • This type of erosion forms valleys, canyons,
    dunes, deltas, and mountain bowls

6
  • Erosion by Glaciers
  • Like huge plows, they carve and shape large
    parts of the Earths surface.
  • This type of erosion forms sharp mountain
    peaks, wide valleys, level plains, and lakes.
  • Erosion by Wind
  • Moves only small rock particles like sand and
    dust.
  • This type of erosion has the greatest effect in
    dry, desert climates.
  • Erosion by Waves
  • The constant pounding of waves erodes the rocks
    along the shoreline.
  • Careless use of land by humans speeds the rate
    of erosion

7
Deposition
  • All of the processes by which eroded materials
    are dropped.
  • There are 4 types of deposits.
  • 1. stream
  • 2. glacial
  • 3. wind
  • 4. waves

8
  • Types of Deposits
  • Stream Deposits
  • Rock and soil are carried any place where the
    flow slows down.
  • These are most commonly found
  • a. At the base of mountains
  • b. At the edge of stream channels
  • c. Where rivers meet a lake or ocean
  • Glacial Deposits
  • Moving glaciers pick up a great deal of rock
    when the glacier stops advancing and begins to
    melt
  • Wind Deposits
  • The sand, silt, and dust carried by the wind is
    deposited when the wind encounters a barrier and
    slows down.
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