Download Weathering and Soil Formation

Weathering and Soil Formation
Table of Contents
Rocks and Weathering
How Soil Forms
Soil Conservation
Weathering and Soil Formation - Rocks and Weathering
Chemical Weathering
As weathering breaks apart rock, the surface
area exposed to weathering increases.
Weathering and Soil Formation - Rocks and Weathering
Which Weathered Faster?
The graph shows the rate of
weathering for two identical
pieces of limestone that
weathered in different locations.
Weathering and Soil Formation - Rocks and Weathering
Which Weathered Faster?
Reading Graphs:
What does the x-axis of the
graph represent?
Time in years
Weathering and Soil Formation - Rocks and Weathering
Which Weathered Faster?
Reading Graphs:
What does the y-axis of the
graph represent?
The thickness of stone lost to
weathering
Weathering and Soil Formation - Rocks and Weathering
Which Weathered Faster?
Reading Graphs:
How much thickness did
Stone A lose in 1,000 years?
How much thickness did
Stone B lose in the same
period?
Stone A lost about 8.5
millimeters; Stone B lost
slightly more than 4
millimeters.
Weathering and Soil Formation - Rocks and Weathering
Which Weathered Faster?
Drawing Conclusions:
Which stone weathered at a
faster rate?
Stone A weathered at a faster
rate.
Weathering and Soil Formation - Rocks and Weathering
Which Weathered Faster?
Inferring:
Since the two identical pieces
of limestone weathered at
different rates, what can you
infer caused the difference in
their rates of weathering?
They were exposed to
different climate conditions.
Weathering and Soil Formation - Rocks and Weathering
Relating Cause and Effect
A cause makes something happen. An effect is what
happens. As you read, identify the causes of chemical
weathering. Write them in a graphic organizer like the one
below.
Causes
Oxygen
Effect
Water
Acid rain
Chemical
weathering
Weathering and Soil Formation - Rocks and Weathering
More on Weathering
Click the PHSchool.com button for an
activity about weathering.
Weathering and Soil Formation
End of Section:
Rocks and
Weathering
Weathering and Soil Formation - How Soil Forms
What Is Soil?
Loam, a type of soil, is made
up of air, water, and organic
matter as well as materials
from weathered rock.
Weathering and Soil Formation - How Soil Forms
What Is Soil?
Soil particles range in size from gravel to clay particles too
small to be seen by the unaided eye. The sand, silt, and clay
shown here have been enlarged.
Weathering and Soil Formation - How Soil Forms
The Process of Soil Formation
Soil forms as rock is broken down by weathering and mixes
with other materials on the surface. Soil is constantly being
formed wherever bedrock is exposed.
Weathering and Soil Formation - How Soil Forms
Soil Layers Activity
Click the Active Art button to open a browser window and
access Active Art about soil layers.
Weathering and Soil Formation - How Soil Forms
Soil Types
Scientists classify the different types of soil into major groups
based on climate, plants, and soil composition.
Weathering and Soil Formation - How Soil Forms
Living Organisms in Soil
Some soil organisms make humus, the material that makes
soil fertile. Other soil organisms mix the soil and make
spaces in it for air and water.
Weathering and Soil Formation - How Soil Forms
Building Vocabulary
A definition states the meaning of a word or phrase by telling
about its most important feature or function. Carefully read
the definition of each Key Term and also read the
neighboring sentences. Then write a definition of each Key
Term in your own words.
Key Terms:
soil
loam
subsoil
soil
horizon
bedrock
litter
humus
topsoil
decomposer
fertility
Examples:
Soil that
is horizon,
the
weathered
material
on Earth’s
The
Soil
B
is loose,
made
often
up
of
called
aboutsubsoil,
equal parts
usually
of clay,
consists
sand,
surface
in called
which
plants
canwashed
grow. down from the A
and
of
clay
siltand
is
otherloam.
particles
horizon, but little humus.
A
soil horizon
a layer
that
differs in
Bedrock
is the is
solid
layerofofsoil
rock
beneath
thecolor
soil. and
As
plants
shed
they form
a loose
texture
from
theleaves,
layers above
or below
it. layer called
Humus
is
a
dark-colored
substance
that
forms as
litter.
The
horizon
is made
up decay.
of topsoil, a crumbly, dark
plantAand
animal
remains
Decomposers
are
organisms
that break
the
remains
brown soil that is a mixture of humus,
clay,
and
other
The
fertility
of
soil
is
a
measure
of
how
well
the
soil
of
dead
organisms
into
smaller
pieces
and
digest
them
materials.
supports
plant growth.
with
chemicals.
Weathering and Soil Formation - How Soil Forms
Soil
Click the Video button to watch a movie about soil.
Weathering and Soil Formation
End of Section:
How Soil Forms
Weathering and Soil Formation - Soil Conservation
Soil Damage and Loss
Wind erosion is one cause of soil
loss. For example, wind erosion
contributed to the Dust Bowl on the
Great Plains. The Dust Bowl ruined
farmland in western Oklahoma and
parts of the surrounding states.
Wind blew dry particles of soil into
great clouds of dust that traveled
thousands of kilometers.
Weathering and Soil Formation - Soil Conservation
Previewing Visuals
Before you read, preview Figure 13, “The Dust Bowl”. Then
write two questions that you have about the photo and map
in a graphic organizer like the one below. As you read,
answer your questions.
The Dust Bowl
Q. Where was the Dust Bowl?
A. The Dust Bowl was in western Oklahoma and parts of
the surrounding states.
Q. What caused the Dust Bowl?
A. Farming practices exposed the soil so that in times of
drought the topsoil quickly dried out, turned to dust, and
blew away.
Weathering and Soil Formation - Soil Conservation
Links on Soil Conservation
Click the SciLinks button for links on soil conservation.
Weathering and Soil Formation - Soil Conservation
Soil Conservation
Click the Video button to watch a movie about
soil conservation.
Weathering and Soil Formation
End of Section:
Soil
Conservation
Weathering and Soil Formation
Graphic Organizer
Soil Horizons
Bedrock begins to weather
The C horizon forms as bedrock breaks apart.
The A horizon develops from the C horizon where
plants grow in it.
The B horizon develops as clay and minerals wash
down from the A horizon.
Weathering and Soil Formation
End of Section:
Graphic Organizer