Weathering

Learning Targets

• Observe the the ways that rocks are changed as they are broken down by various forces.

Success Criteria

• Safely conduct a scientific investigation.
• Develop an understanding of the forces that break down rocks.
• Create a definition that can be applied to all kinds of weathering.

Roles

• Organizer, Materials Manager/Technician, Time Keeper, Checker, Reader

3 Weathering Experiments

To learn more about the forces that cause changes to the Earth's surface, we will conduct three experiments that simulate the different weathering processes.

#1 - Effects of Acid Rain (Vinegar) on Copper (Pennies)

Question: To what extent does vinegar affect copper pennies?

Materials: 2 pennies, 2 clear plastic dishes, vinegar, water, 2 pipettes, beaker or measuring cup, clock or timer

1. Place a penny in each plastic dish.
2. Place a few drops of white vinegar over the penny in one dish and an equal amount of water in the other. Be sure to use the same amount of each.
3. Observe and record initial (starting) observations below.
4. Make and record further observations after 5 minutes.

Conclusion - Answer the above question based on your observations.

#2 - Effects of Sand on Sugar Cubes

Question: To what extent does sand affect the weathering of rocks?

Materials: 2 sugar cubes, sand, 2 baby food jar with lid, clock or timer

1. Place a sugar cube in each jar.
2. Put 2-3 spoons of sand in one jar.
3. Put lid on each jar and shake each for 1 minute. Record observations below.
4. Shake each jar with two hands for 1 more minute and record observations. CAUTION - you can take lid off to make observations but be careful to not breathe any of the dust!
5. Shake each jar for an additional 1 minute and record final observations.

Data/Results:

After 1 Minutes

After 2 Minutes

After 3 Minutes

Conclusion - Answer the above question based on your observations.

#3 - Effects of Water and Vinegar on Limestone

Question: To what extent does water and vinegar affect the weathering of limestone?

Materials: 2 chalk samples, 2 clear beakers, water, vinegar, beaker or measuring cup, clock or timer

1. Label one beaker “water” and the other “vinegar”.
2. Pour 25 mL vinegar into one beaker and 25 mL water in the other beaker.
3. Place 1 piece of chalk in each cup.
4. Record your initial observations in a data table.
5. Let stand for 5 minutes and record final observations.

Conclusion - Answer the above question based on your observations.

Back to Teams...

• Discuss your experiences with the experiments
  • What was your hypothesis?
  • What actually happened?
  • How were the experiments similar and different?

Definition

• Create a group definition that works for all kinds of weathering.

Questions to Ponder

• Can you describe something near where you live that has been weathered? What kind of weathering has it been shaped by?
• How would you stop weathering from happening to something that is valuable?

Weathering Gizmo Exploration

Learning Targets

• Observe the the ways that rocks are changed as they are broken down by various forces.

Success Criteria

• Develop an understanding of the forces that break down rocks.
• Tell the difference between mechanical and chemical weathering.
• Understand the time scales involved in the weathering of rocks.

Weathering Gizmo

• Weathering is the breakdown of rock at Earth's surface through physical or chemical means. You will learn about the different types of mechanical and chemical weathering, then use a simulation to model the effects of weathering on different types of rocks in varying climate conditions.

Day One

Activity A: Types of weathering

Get the Gizmo ready: Select the ANIMATION tab. Check that Frost wedging is selected.

Introduction:

• Mechanical weathering occurs when rocks are physically broken or worn down. Chemical weathering occurs when the minerals in the rock are changed by chemical reactions.

Question: What are the most common ways in which weathering occurs?

Observe: Read the text about frost wedging, then click Play.

• In the process of frost wedging, how does ice cause cracks in rocks to become larger?
• Is frost wedging more important in a warm or a cold climate?

Observe: Read about and look at the animations for the other major types of weathering: Abrasion, Pressure release, Dissolving, Clay formation, and Rusting.

• What are three different ways that rocks can be worn down by abrasion?
• How can a large block of granite form layers like an onion?
• What type of rock is affected by dissolving, and what features result?
• How does clay formation affect a rock?
• Which part of a rock will undergo rusting?

Back to Teams

• Compare: Check your work by comparing your answers to Activity A.
• Interpret: Based on the descriptions and images, guess which type of weathering is shown by each of the images below. Explain each answer.

Day Two

Learning Targets

• Observe the the ways that rocks are changed as they are broken down by various forces.

Success Criteria

• Develop an understanding of the forces that break down rocks.
• Tell the difference between mechanical and chemical weathering.
• Understand the time scales involved in the weathering of rocks.

Questions to Ponder

• How has your understanding of weathering changed since completing Day One?
• What more do you think there is to learn about weathering?

Activity B: Weathering of different rocks

Get the Gizmo ready: On the SIMULATION tab, click Reset. Set the Average temperature to 25 °C and Precipitation to 250 cm/yr.

Introduction: The Weathering Gizmo lets you explore weathering of four common rocks. Granite is a very hard rock formed from the crystallization of magma deep underground. Sandstone forms when sand grains become cemented together. Limestone is formed from ancient corals, shells and skeletons. Shale is formed from compacted mud.

Question: How does weathering affect different rock types?

Observe: Below Rock type, select Granite. Click Fastplay and run a simulation of about 100,000 years. Describe what you see: Look at Weathered rock above the outcrop. How much rock was weathered?

Observe: Click Reset. Repeat the same procedure for Sandstone, Limestone, and Shale. After 50,000 years, stop and describe your observations in your notebook. List the amount of weathered rock for each type of rock. Sandstone, Limestone, Shale

Compare: Compare the results of weathering of different landscapes:

• Which rock types tend to weather into rounded shapes?
• Which rock weathers into caves and lumpy hills?
• Which rock weathers most quickly? Most slowly?

Observe: Click Reset. Select Granite and click Fastplay. Run the simulation until you can see large cracks forming in the rock. (This may take a while, be patient!) What type of weathering forms these cracks? (Hint: You may need to review the different types of weathering on the ANIMATION tab.)

Infer: Some types of weathering only affect certain kinds of rocks. The Types of weathering that apply to each kind of rock are listed above the outcrop. If a type of weathering does not affect the selected rock, it is faded. Select each rock and list the types of weathering that affect it. Granite: Sandstone: Limestone: Shale:

Back to Teams

• Compare: Check your work by comparing your answers to Activity B.
• Interpret: Based on the weathering patterns, guess the rock type shown in each photo.