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.