Transcript Weathering, Erosion, & Deposition

 Weathering is the breaking down of rocks into
smaller and smaller pieces.
 There are two types of weathering:
 Mechanical Weathering
 Chemical Weathering
 Mechanical weathering
is the breakdown of rock
by physical means.
 Some examples are:
 Ice (Ice wedging/frost
action is a series of
freezing and thawing)
 Abrasion (wearing away
of rock by the mechanical
action of other rocks)
 Wind, Water, and Gravity
are different forms of
abrasion.
 Chemical Weathering is
when rocks break down as
a result of chemical
reactions causing the
composition of rocks to
change.
 Some examples are
 Acid (found in water,
precipitation or lichens)
 Air (Oxygen reacts with
iron in a process called
Oxidation which forms
Rust).
 Some rocks and minerals are more resistant to
weathering, while others experience weathering more
quickly.
 Weathering happens more quickly in hot and wet
climates.
 Climate and rock type are the most important
factors in the rate of weathering.
 Weathering happens more quickly when there is more
surface area.
 For example, a pile of pebbles will weather more
quickly than one large boulder.
 Erosion is the process
through which soil and
sediment are
transported from one
place to another.
 Erosion is primarily
responsible for the
formation of river
systems.
 Wind erosion occurs
when wind blows over
sand. The sand is
deposited when the wind
hits an obstacle.
 The process of wind
erosion is called
deflation.
 The movement of wind
erosion is a bouncing
movement called
saltation.
 Wave erosion occurs
 Glacial erosion is the
along shorelines.
mass movement of
glaciers.
 Mass movement is the movement of material down a
slope through gravity.
 Examples: Landslide, Mudslide, Creep, Slump
 Mass movement can occur quickly (landslide, rock
falls) or slowly (creep).
 Soil is valuable because living things need it and
fertile soil takes a long time to create.
 To prevent erosion of valuable soil, we can plant
plants to help hold the soil in place.
 If plants are removed, a
situation like the dust bowl
in the 1930’s could take place.
 Farmers will also leave the
stalks of previous year’s crops
to help hold the soil in
place.
 Deposition is the
process through which
soil and sediment is
dropped off or deposited.
 Two examples of where
this occurs are on
beaches and at river
deltas.