Transcript Weathering, Erosion, and Deposition

Weathering
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All of the processes that
break rock into smaller
pieces
Rocks can be
weathered only when
they are exposed to the
earth’s surface.
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.
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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
Erosion
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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.
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 water’s
current, they wear away the channel through which the
stream flows.
*This type of erosion forms: valleys, canyons, dunes, deltas,
and mountain bowls
Erosion by Glaciers:
Like huge plows, they carve and shape large parts of
the Earth’s 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
Deposition
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All of the processes by
which eroded materials
are dropped.
There are 4 types of
deposits.
1. stream
2. glacial
3. wind
4. waves
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.