ESC 1000L Space Science Video Notes Name:
____________
Earth Revealed #15: Weathering and Soils(1992)
Please watch the video in
class. Take notes on the Earth Revealed Disc #15 disc Weathering and Soils.
Please circle each of the Chapter 4 vocabulary words discussed in the video.
When the film is finished and after
reading Chapter 4:Weathering, Soils, and Mass wasting finished, write questions
with answers that a student should be able to answer if she/he viewed this video.
You should have at least two or more questions for each chapter. List the most
significant discovery you made about Weathering and Soils which you did not
know before watch the film.
Play Video: http://www.learner.org/resources/series78.html
Chapter 4: Weathering,
Soils, and Mass wasting:
Key Concepts
Chapter 4: Weathering, Soil, and Mass Wasting
After
reading and studying
Concept 1: Define and describe the processes of weathering and erosion, including examples of negative and beneficial effects of these processes.
Concept
2: Use examples to explain the difference
between mechanical and chemical weathering and the variation in the rate of
weathering.
Concept
3: Discuss soil composition, texture,
structure, formation, and classification.
Concept
4: Provide examples of various types of mass
wasting and describe the controls and triggers of this process.
To evaluate and reinforce your understanding of any or
all of the Key Concepts, look at the selection bar on the left side of
this page. Select and click on the corresponding Concept Quiz or Chapter
Test and answer the questions provided.
Chapter Summary
The
following statements summarize and describe many of the key terms and concepts
presented in the chapter.
· External processes include (1) weathering—the disintegration and decomposition of rock at or near the surface, (2) mass wasting—the transfer of rock material downslope under the influence of gravity, and (3) erosion—the incorporation and transportation of material by a mobile agent, usually water, wind, or ice. They are called external processes because they occur at or near Earth's surface and are powered by energy from the Sun. By contrast, internal processes, such as volcanism and mountain building, derive their energy from Earth's interior.
·
Mechanical
weathering is the physical breaking up of rock into
smaller pieces. Chemical weathering alters a rock's chemistry,
changing it into different substances. Rocks can be broken into smaller
fragments by frost wedging, unloading, and biological
activity. Water is by far the most important agent of chemical
weathering. Oxygen in water can oxidize some materials, while carbon dioxide
(CO2) dissolved in water forms carbonic acid. The chemical
weathering of silicate minerals frequently produces (1) soluble products
containing sodium, calcium, potassium, and magnesium, (2) insoluble iron
oxides, and (3) clay minerals.
·
The rate at which rock
weathers depends on such factors as (1) particle size—small
pieces generally weather faster than large pieces; (2) mineral makeup—calcite
readily dissolves in mildly acidic solutions, and silicate minerals that form
first from magma are least resistant to chemical weathering; and (3) climatic
factors, particularly temperature and moisture. Frequently, rocks
exposed at Earth's surface do not weather at the same rate. This differential
weathering of rocks is influenced by such factors as mineral makeup and
degree of jointing.
·
Soil is a combination of mineral and organic matter, water,
and air—that portion of the regolith (the layer of rock and
mineral fragments produced by weathering) that supports the growth of plants.
Soil texture refers to the proportions of different particle sizes (clay, silt,
and sand) found in soil. The most important factors that control soil
formation are parent material, time, climate, plants and animals, and
topography.
·
Soil-forming processes
operate from the surface downward and produce zones or layers in the soil
called horizons. From the surface downward the horizons are
designated as O, A, E, B, and C, respectively.
·
In the
·
Soil erosion is a
natural process; it is part of the constant recycling of Earth materials that
we call the rock cycle. Rates of soil erosion vary from one place
to another and depend on the soil's characteristics as well as such factors as
climate, slope, and type of vegetation. Human activities have greatly
accelerated the rate of soil erosion in many areas.
·
Weathering creates
mineral deposits by concentrating metals into economically valuable deposits.
The process, called secondary enrichment, is accomplished by either (1) removing undesirable materials and leaving the
desired elements enriched in the upper zones of the soil or (2) removing and
carrying the desirable elements to lower soil zones where they are redeposited and thus become more concentrated. Bauxite, the
principal ore of aluminum, is one important ore created by secondary
enrichment.
·
In the evolution of
most landforms, mass wasting is the step that follows weathering. The combined
effects of mass wasting and erosion by running water produce stream valleys. Gravity
is the controlling force of mass wasting. Other factors that influence
or trigger downslope movements are saturation of the
material with water, oversteepening of slopes beyond
the angle of repose, removal of anchoring vegetation, and ground
vibrations from earthquakes.
·
The various processes
included under the name of mass wasting are classified and described on the
basis of (1) the type of material involved (debris, mud, earth, or rock), (2)
the kind of motion (fall, slide, or flow), and (3) the rate of movement (fast,
slow). The various kinds of mass wasting include the more rapid forms called slump,
rockslide, debris flow, and earthflow,
as well as the slow movements referred to as creep and solifluction.
Earth Revealed #15: Weathering and
Soils
The Cleopatra’s Needle obelisk in New York City’s Central Park is severely
weathered after only 75 years, whereas the dry climate of Egypt has preserved
similar structures in that country for millennia. This program shows how
weather, climate, chemicals, temperature, and type of substrate factor into
rock and soil erosion. Environmental connections are also considered.
.
Play
Video: http://www.learner.org/resources/series78.html
Video Notes:
Chapter 4:
Weathering, Soil, and Mass Wasting Word List
Angle of repose |
Frost wedging |
Sheeting |
Chemical weathering |
Horizon |
Slide |
Creep |
Internal processes |
Slump |
Debris flow |
Lahar |
Soil |
Differential weathering |
Leaching |
Soil profile |
Earth flow |
Mass wasting |
Soil Taxonomy |
Eluviation |
Mechanical weathering |
Soil texture |
Erosion |
Parent material |
Solifluction |
Exfoliation dome |
Permafrost |
Solum |
External processes |
Regolith |
Spheroidal weathering |
Fall |
Rockslide |
Talus slope |
Flow |
Secondary enrichment |
Weathering |
Video Notes continued:
Student Questions (with Answers):
1.
2.
Most Significant Discovery (discoveries):
What happened to Cleopatra's Needle?
Why does rock material change when exposed to surface conditions?
Discuss mechanical weathering.
Describe exfoliation, and the fracturing of rock due to pressure release.
What is ice wedging?
How much does water expand when it freezes?
Discuss chemical weathering.
How do mechanical and chemical weathering work together to disintegrate rock?
What are the principle agents of chemical weathering?
How does rain water become acidic?
How do climate and temperature affect the rate of weathering?
Discuss the formation of acid rain and its impact on surface materials.
Discuss the formation of soils and soil horizons.
What circumstances led to the Dust Bowl of the 1930's?
How do irrigation practices affect the long term health of soils?
What have you seen blowing away from the equipment in every scene during the last 10 minutes of this episode?
Why is soil one of our most important natural resources.
Play
Video: http://www.learner.org/resources/series78.html
Video Notes:
Student Questions (with Answers):
1.
2.
Most Significant Discovery (discoveries):
What is mass wasting?
Why does mass wasting occur everywhere?
How do human activities help trigger mass wasting events?
Describe how the angle of a slope affects mass wasting.
Describe how water in the ground contributes to mass wasting.
What is creep, and what causes it to occur?
What is slump?
Discuss landslides at Portuguese Bend.
How has road building contributed to the problems?
Why are many Portuguese Bend landowners unable to move?
Discuss mudflows and debris flows.
Describe rock slides.
What factors do engineering geologists look at when studying slope stability?
How do heavy rains contribute to mud and debris flows?
How does human activity contribute to mass wasting processes?