Transcript Weathering Ch. 10

Weathering Ch. 10
By: Kelsey Bowman
and Tiffany Gee
What is weathering?
• Weathering is the breakdown of rock
into smaller pieces.
What are the two types of
weathering?
• The two types of weathering are
chemical and mechanical.
– Chemical weathering is the breaking
down of rock and minerals into new
substances by chemical means.
– Mechanical weathering is the breaking
down of rock into small pieces by physical
means.
Mechanical Weathering
• Abrasion is the action of rocks and
sediments grinding against each other
and the wearing away of exposed
surfaces.
– For example, abrasion occurs in the body of
rivers when rocks and pebbles roll along the
bottom. They eventually become river rocks.
Mechanical Weathering cont.
• Mechanical weathering also occurs
with plants and animals.
– The root wedging in plants is an example of
mechanical weathering.
– Ice wedging is the process of which water seeps
into a crack in a rock and freezes. This is a
form of mechanical weathering.
– Earthworms separating the soil is also an
example of mechanical weathering.
Chemical Weathering
• Acid precipitation contains acid that
is a form of chemical weathering.
– For example, acid precipitation occurs in bronze statues.
It also occurs in granite and makes the bonds between
mineral grains weaken as chemical weathering continues.
How does rust form?
• Oxidation is the chemical reaction in
which an element such as iron
combines with oxygen to form an
oxide. Rust is the most familiar result
of oxidation.
Caves
• Caves are a form of chemical
weathering
Differential Weathering
• The process by which softer, less
weather-resistant rocks wear away,
leaving harder, more weather-resistant
rocks behind.
– For example, the Devil’s Tower is a landform known as a
volcanic neck. When the molten solidified it was
protected from weathering by the softer rock of the
volcano.
What are soil and bedrock?
• Soil is a loose mixture of small mineral
fragments and organic material.
• Beneath the soil, is a layer of rock
know as bedrock.
• Sources of soil: parent rock. This rock
forms from granite that forms from
limestone soil.
Things that involve soil:
• Humus is small particles of
decay plant and animal
material. Humus is located
in Horizon A which is a
layer of topsoil.
– Topsoil is the top layer of
soil.
– When rainwater travels down
through the horizons of the
soil, it dissolves the nutrients
and minerals which is known
as the process of leaching.
The Importance of soil:
• It’s very important for our soil to be
taken care of, because it has many
benefits for our planet.
– One way you can help the soil is by soil conservation. This
is the various methods by which humans take care of the
soil.
– We can also try to prevent erosion in the soil. Erosion is
the process by which wind and water transfer soil and
sediment from one location to another.
Summary of Vocabulary
• During this
PowerPoint
presentation, you
have learned the
following vocabulary
words that deal with
weathering and
erosion. Just in case
you have forgotten
here is a recap of the
words:
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Weathering
Mechanical Weathering
Abrasion
Chemical Weathering
Acid Precipitation
Oxidation
Differential Weathering
Soil
Bedrock
Parent Rock
Humus
Topsoil
Leaching
Soil Conservation
Erosion