weathering and soil formation rocks and weathering how soil forms soil conservation table of...
TRANSCRIPT
Weathering and Soil Formation
Rocks and Weathering
How Soil Forms
Soil Conservation
Table of Contents
Weathering and Soil Formation
Chemical Weathering
- Rocks and Weathering
As weathering breaks apart rock, the surface area exposed to weathering increases.
Weathering and Soil Formation
Which Weathered Faster?
The graph shows the rate of weathering for two identical pieces of limestone that weathered in different locations.
- Rocks and Weathering
Weathering and Soil Formation
Which Weathered Faster?
Time in years
Reading Graphs:
What does the x-axis of the graph represent?
- Rocks and Weathering
Weathering and Soil Formation
Which Weathered Faster?
The thickness of stone lost to weathering
Reading Graphs:
What does the y-axis of the graph represent?
- Rocks and Weathering
Weathering and Soil Formation
Which Weathered Faster?
Stone A lost about 8.5 millimeters; Stone B lost slightly more than 4 millimeters.
Reading Graphs:
How much thickness did Stone A lose in 1,000 years? How much thickness did Stone B lose in the same period?
- Rocks and Weathering
Weathering and Soil Formation
Which Weathered Faster?
Stone A weathered at a faster rate.
Drawing Conclusions:
Which stone weathered at a faster rate?
- Rocks and Weathering
Weathering and Soil Formation
Which Weathered Faster?
They were exposed to different climate conditions.
Inferring:
Since the two identical pieces of limestone weathered at different rates, what can you infer caused the difference in their rates of weathering?
- Rocks and Weathering
Weathering and Soil Formation
Relating Cause and EffectA 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.
Chemical weathering
Oxygen
Water
Acid rain
- Rocks and Weathering
Causes
Effect
Weathering and Soil Formation
More on Weathering
Click the PHSchool.com button for anactivity about weathering.
- Rocks and Weathering
Weathering and Soil Formation
End of Section:Rocks and Weathering
Weathering and Soil Formation
What Is Soil?
- How Soil Forms
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
Soil Layers Activity
Click the Active Art button to open a browser window and access Active Art about soil layers.
- How Soil Forms
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
Building VocabularyA 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.
- How Soil Forms
Key Terms: Examples:
soil Soil is the loose, weathered material on Earth’s surface in which plants can grow.
bedrock Bedrock is the solid layer of rock beneath the soil.
humus Humus is a dark-colored substance that forms as plant and animal remains decay.
fertility The fertility of soil is a measure of how well the soil supports plant growth.
Key Terms: Examples:
loam
soil horizon
topsoil
Soil that is made up of about equal parts of clay, sand, and silt is called loam.
A soil horizon is a layer of soil that differs in color and texture from the layers above or below it.
The A horizon is made up of topsoil, a crumbly, dark brown soil that is a mixture of humus, clay, and other materials.
Key Terms: Examples:
subsoil
litter
decomposer
The B horizon, often called subsoil, usually consists of clay and other particles washed down from the A horizon, but little humus.
As plants shed leaves, they form a loose layer called litter.
Decomposers are organisms that break the remains of dead organisms into smaller pieces and digest them with chemicals.
Weathering and Soil Formation
Soil
Click the Video button to watch a movie about soil.
- How Soil Forms
Weathering and Soil Formation
End of Section:How Soil Forms
Weathering and Soil Formation
Soil Damage and Loss
- Soil Conservation
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
Previewing VisualsBefore 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.
- Soil Conservation
Weathering and Soil Formation
Links on Soil Conservation
Click the SciLinks button for links on soil conservation.
- Soil Conservation
Weathering and Soil Formation
Soil Conservation
Click the Video button to watch a movie aboutsoil conservation.
- Soil Conservation
Weathering and Soil Formation
End of Section:Soil
Conservation
Weathering and Soil Formation
Graphic Organizer
The C horizon forms as bedrock breaks apart.
Bedrock begins to weather
Soil Horizons
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