Melanie Giambattista
Lesson 6a – Erosion
Table of Contents
1. Teacher Notes
2. Engage Activity – Mechanical Weathering of Rocks (day 1)
a. Engage Activity 2 – Rock Erosion
3. Day 2 – Demo
4. Understanding Concepts Assignment
Teacher Notes
Definitions:
Erosion – is the movement of rock and mineral grains from one place to another. Sediment
comes from larger rocks that have broken down or worn away through weathering. Rocks can
be weathered mechanically or chemically.
Mechanical Weathering – is the physical break-up or disintegration of rocks.
Ex) -Gravity causes rocks to fall down a cliff and break apart
-rocks, rolling down a slope or in a fast-moving stream rub and bump against each other,
becoming smoother and rounded
-temperature change: during the freeze-thaw period, between winter and spring, snow
and ice melt in the daytime, allowing water to seep into cracks in the rock. At night,
when the temperature falls below 0*C, the water freezes and expands, pushing the
cracks wider apart. This causes the rock to slowly break apart.
-wind and water wear away the surfaces of rocks and carry the pieces to another place,
where the pieces build up. (What is this build up process called?)
Erosion by Wind:
-ex) the devastating dust storms in the Prairies during the severe droughts in the 1930s
demonstrated the wind’s power. The rich soil was blown away, leaving behind layers that were
not suitable for crops
-wind wears away rock (like sandpaper on wood) by driving soil and sand particles against it for
thousands of years
Erosion by Water:
-large waves hitting the shoreline and knocking soil from the banks into the water
-fast moving water also knocks soil from the banks into the water
-pounding waves breaks down rocks into smaller and smaller pieces – eventually sand
-mountain stream, over thousands of years, gradually wears away even the hardest of rocks
Erosion by Ice: Nature’s Bulldozer
-glaciers
-slowly move downhill due to their immense weight. The weight of the glaciers scrapes the
ground causing the land to change around it.
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Melanie Giambattista
-once a glacier starts to melt, it leaves the broken rocks it eroded in enormous piles called
moraines.
Chemical Weathering – breaks down minerals through chemical reactions. Some material may
be dissolved and some may be weakened.
-chemical weathering occurs when water, air, and other materials react with the rocks,
changing the substances that make up the rocks. (water is the main cause)
-ex) acid rain – acidic rainwater, which contains dissolved chemicals from air pollution, reacts
with limestone and dolomite.
Biological weathering-is the physical or chemical breakdown of rock caused by living
organisms, such as plants, animals, bacteria, and fungi.
Ex) when a plant root wedges into a rock by forcing its way into a crack
Ex) acidic fluids produced by plant roots, bacteria, fungi and some insects and small
animals can cause chemical reactions
Engage Activity – Erosion from Running Water
From: Nelson Science and Technology 7, The Earth’s Crust – 4.6
Make a cone-shaped pile of sand in a shallow pan. Flatten the top, as in Figure 5, and place an
ice cube carefully on the cone. Allow the ice cube to melt.
1. What changes do you observe in the sand mountain as the ice cube melts?
2. What is erosion? Write a definition, without using a dictionary or textbook, in your
science journal.
Engage Activity 2 – Rock Erosion
From: Teaching Science to Children an Inquiry Approach, 6th edition (page 292)
Fill a small jar half full of rock chips consisting mostly of sandstone, limestone or shale. Add
water. Have pupils take turns shaking the jar vigorously for several minutes. Observe the chips
carefully under a magnifying glass. Inspect the water and the bottom of the jar for any deposits.
1. Compare the appearance of the chips before and after shaking the jar.
2. Observing that the chips are generally smaller and more rounded after shaking than
before
3. Inferring that the shaking ground off tiny bits of rock which clouded the water and
settled to the bottom.
4. Generalizing to relate the activity to the mechanical erosion of rocks
Day 2 Demo – stole from Adam Krammer off the wiki
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Melanie Giambattista
TITLE: "IT'S EATING AWAY AT YOU"
AUTHOR: Judy Grunke, Weiser Middle School;
Weiser, Idaho (borrowed from Falma Moye)
GRADE LEVEL: 6-8, Earth or Physical Science
OVERVIEW: Acid rain is a major pollutant in the world today. This activity is designed to show
the effect of acid rain on rock, edifices, and sculptures.
PURPOSE: To show the effect of acid rain on limestone rock.
OBJECTIVE(s): The student will be able to:
1. Demonstrate, using chalk and vinegar solution, the chemical reaction of acid on limestone.
2. Explain what happens in this process.
3. Identify the compounds used in the reaction and the gas which is given off.
4. Tell where acid rain originates.
5. Explain the effect of acid rain on limestone buildings and statuary.
RESOURCES/MATERIALS:
CLASS: Textbook, acid rain
FOR EACH LAB GROUP:
 vinegar solution
 chalk
 eye dropper
 pan to set chalk in and to catch vinegar
ACTIVITY AND PROCEDURES:
1. Place a piece of chalk in pan.
2. Using an eyedropper, have one student drop vinegar onto the chalk in a constant stream.
3. Observe the fizzing on the surface of the chalk when the vinegar is dropped.
4. Notice the crumbling of the chalk.
**• Air pollution is a major cause of acid rain. When rain becomes more acidic than normal it
can damage soil, water, building materials, plants, animals, and humans.
• Chalk is made from calcium carbonate (CaCO3)/calcite.
• In this activity the vinegar, which is acidic, reacts with the chalk forming carbon dioxide gas
(the bubbles you see during the reaction are the carbon dioxide gas forming), water, and
another calcium compound.
• The remaining material no longer looks like the original chalk.
• The chalk remains the same in the water.
• This simple experiment demonstrates the effects of acid rain on limestone or calcium
carbonate-containing statues and buildings.
• The acid rain dissolves the calcium carbonate causing the surfaces to become rough and the
intricate detail of the statue/building to be lost."
Source and further information:
http://peer.tamu.edu/NSF_Files/tk.asp?file=AcidRain1_resultstable||doc&id=185
http://www.answerbag.com/q_view/1302669
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Melanie Giambattista
Understanding Concepts Assignment
1. What is erosion?
2. What is weathering?
3. What is the difference between weathering and erosion?
4. Make a chart explaining the differences between mechanical,
biological, and chemical weathering (include an example of each)
5. Water is an agent of both chemical and mechanical weathering.
Explain.
6. Some scientists list gravity as one of the causes of erosion
because slopping land erodes more quickly than flat land. Why?
7. What kinds of erosion would you expect to affect a farmer’s field?
List the possibilities.
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