warm-up weathering and soil - edgenuity inc.€¦ · weathering and soil 2 slide weathering...
TRANSCRIPT
© Edgenuity, Inc. 1
Warm-Up Weathering and Soil
?
Lesson Goals
Identifyfactors thataffect the rateof weathering.
Explain howsoil is formed.
Classifydifferent typesof soil.
Distinguishbetweenmechanicaland
weathering.
Describe the
of soil.
Lesson Question
Words to Know
Fill in this table as you work through the lesson. You may also use the glossary to help you.
abrasionthe process of rocks and particles scraping against
one another, away their surfaces
bedrock a layer of solid rock found beneath
chemical weatheringthe of rocks that also changes
their mineral composition
erosion the process by which of rock are
loosened and carried away
fertility the ability of soil to agricultural plant growth
WK2
© Edgenuity, Inc. 2
Warm-Up Weathering and Soil
Words to Know
humus dark, highly organic matter in soil
mechanical weatheringthe physical breakdown of rocks without changing
their composition
oxidationchemical reaction in which a substance combines with
sedimentsmall, solid pieces of material from rocks or
soil an accumulation of loose, material
covering much of Earth’s surface
soil horizon a recognizable of soil with characteristic properties
soil profilea section of soil that ranges from the
surface to the bedrock
uniformitarianismthe idea that Earth’s features have formed gradually
by processes that are still occurring
weathering the breakdown of rocks into particles by natural processes
WK2
© Edgenuity, Inc. 3
Warm-Up Weathering and Soil
Famous Landmarks
A variety of landmarks are formed by being broken down.
The Canyon National Park, Utah
© Edgenuity, Inc. 4
Weathering and Soil
2Slide
Weathering
Weathering is the of rocks into smaller particles by natural processes.
• It can be caused by:
• .
• wind.
• cold and heat.
• gases.
• The small particles created by weathering are called .
Erosion
Erosion is the process by which fragments of rock are loosened and
away.
• Sediment is transported as solid material or components.
• The most common transporting agent is water.
• Other transporting agents include and ice.
Instruction
© Edgenuity, Inc. 5
Weathering and Soil
2Slide
Uniformitarianism
Uniformitarianism is a principle in geology that suggests Earth’s geologic
processes acted in the manner and intensity in the past as they do in the present.
• Accounts for all geologic change
• Shows how layers of collected on Earth’s surface
The present is the key to the past.
Mechanical Weathering
In mechanical weathering, rocks are broken down into smaller pieces
changing their composition.
Mechanical weathering is caused by:
• and thawing.
• release of .
• plant growth.
• action of .
• abrasion.
Instruction
4
© Edgenuity, Inc. 6
Instruction Weathering and Soil
Factors That A�ect Rates of Weathering
Two key factors a�ect the rate of weathering—rock type and .
• Rock type
• Minerals that easily weather faster.
• Softer minerals apart more easily.
• Porous minerals weather more easily.
7
4Slide
Chemical Weathering
In chemical weathering, rocks are broken down, and their composition
. Chemical weathering is caused by:
• .
• .
• carbon dioxide.
• organisms.
• rain.
© Edgenuity, Inc. 7
Instruction Weathering and Soil
7Slide
Factors That A�ect Rates of Weathering
Climate is the single most important factor that a�ects the rate of weathering.
• Chemical reactions occur faster at higher .
• Warm climates favor weathering.
• Cold climates favor mechanical weathering, principally
and thawing.
• The more moisture, or precipitation present, the more noticeable the weathering
Soil
Soil is an of loose, weathered material covering much of
Earth’s surface.
Bedrock is a solid layer of rock lying beneath Earth’s soil layer. Bedrock:
• is the source of rock and mineral that make up soil.
• is not weathered if it is not exposed to and water.
10
© Edgenuity, Inc. 8
Instruction Weathering and Soil
Soil Composition
• Soil is a mixture of:
• rock particles—sand, silt, and clay.
• .
• organic material—humus.
• water.
• air.
• Fertility refers to the ability of soil to plant growth.
Soil Texture
The texture of soil depends on its particle .
• – fine
grains, very little space for water
• – coarse
grains, loose, water drains quickly
• – medium
grains, retains water
10Slide
© Edgenuity, Inc. 9
Instruction Weathering and Soil
12Slide
Soil Profile
A soil profile is a section
of soil that ranges from the surface to the
.
• Each layer of a soil profile is
referred to as a soil .
• Horizon O is the top layer,
where is
present.
• Horizon A is topsoil.
• Horizon B is subsoil.
• Horizon C contains weathered rock.
© Edgenuity, Inc. 10
Instruction Weathering and Soil
12Slide
Formation of Soil Horizons
Soil forms as rock is broken down by and mixes with other materials.
• Horizon O forms at the surface due to the accumulation of organic material.
• Horizon A is mineral rich and forms due to
organic material from above.
• Horizon B undergoes the most change and no longer resembles parent material.
• Horizon C features parent material and is barely
a�ected by the formation process.
Rate of Soil Formation
The rate of soil formation depends on climate and type of parent material.
• Climate
• : Warmer weather creates soil faster.
• : More precipitation creates soil faster.
• Type of parent material
• composition: Some minerals are more resistant
to weathering.
• : Rocks that have a larger grain size break down
more quickly.
• Layers: Rocks with clearly defined layers undergo weathering at a faster pace.
© Edgenuity, Inc. 11
Instruction Weathering and Soil
Soils of America
In the Plains, where many crops are grown, the soils are mostly
, which are fertile soils.
In the southeastern portion of the country, there is a lot of yellow-orange,
representing , which is weathered soil.
15Slide
Soil Classification
Soil scientists recognize major orders of soils.
• The groups are based on:
• .
• type.
• soil .
Gelisols: frozen Histosols: organic, wet
Spodosols: sandy
Andisols: volcanic
Oxisols: very weathered
Vertisols: shrink and swell
Aridisols: very dry
Ultisols: weathered
Mollisols: fertile Alfisols: lightly weathered
Inceptisols: young
Entisols: newly formed
© Edgenuity, Inc. 12
Instruction Weathering and Soil
15Slide
Organisms and Soil
Organisms have a great e�ect on soil.
• Formation of humus
• litter
•
• Mixing of soil by earthworms and burrowing animals
© Edgenuity, Inc. 13
Summary Weathering and Soil
?
2Slide
Review: Key Concepts
Weathering is the breakdown of rocks into smaller pieces of sediment. The rate of weathering is a�ected by the type of rock and the climate.
Weathering
• Physical breakdown of rock into smaller pieces without changing the rock’s minerals
Weathering
• Chemical breakdown of rock that includes changing the minerals present in the rock
Answer
Lesson Question How does weathering a�ect Earth’s surface?
© Edgenuity, Inc. 14
Summary Weathering and Soil
Review: Key Concepts
Weathered material eventually forms soil.
Soil Soil Soil
• Texture is determined by particle size.
• Loam is a combination of clay, silt, and sand.
• Humus is rich in nutrients.
• Weathering forms soil.
• The soil profile shows layers of soil as soil horizons.
• Soil is classified into twelve major groups based on climate and soil composition.
Use this space to write any questions or thoughts about this lesson.
2Slide