Weathering and Erosion

Overview: As you’ve learned in the readings, weathering is the process where rock is broken down into smaller pieces or dissolved. Erosion happens when sediment or rock is transported to another place by water, wind or gravity. There are two types of weathering: chemical and mechanical. In this lab, you will explore the different types of weathering and learn how to recognize causes of erosion.

Safety:
Read through all of the instructions for this laboratory activity before beginning. Follow the instructions closely and observe established laboratory safety practices.

Time Requirements:
Preparation: 15 minutes
Activity 1: 15 minutes
Activity 2: 15 minutes
Activity 3: 15 minutes

Materials needed from the Carolina Biological equipment and lab kits:
Graduated cylinder (from Carolina Biological equipment kit)
Ruler (from Carolina Biological equipment kit)
Steel sphere (from Carolina Biological Density lab kit)
Clay (from Carolina Biological Groundwater and Surface Water Interactions lab kit)

Materials needed but not supplied in the lab kit:
Graham crackers or other crackers with holes in the top
Straw
Plate

Procedure:

Activity 1:
1) Place the cracker oriented with the hole-side up. Prop it up at an angle using the clay.
2) Fill the graduated cylinder with 5 mL of water and gently pour it over the elevated end of the cracker.
3) Wait 5 minutes.
4) Fill the graduated cylinder with another 5 mL of water and gently pour it using the same method you used in Step 2.
5) Observe the cracker, looking for changes to the surface of the cracker.
6) Observe the water in the bottom of the plate, looking for particles present.
7) Take a picture of your results.
8) Dispose of the water and the cracker. Carefully clean the clay and the graduated cylinder and return them back to your lab and equipment kits. Clean the plate to use in Activity 2.

Activity 2:
1) Place a new cracker on the plate.
2) Drop the steel sphere from varying heights 5 times to simulate rocks or other material falling from above.
3) Observe the cracker, making note of where the cracker breaks and the relative sizes of the particles.
4) Take a picture of your results.
5) Carefully clean the steel sphere and return it back to your lab kit.
6) Save this cracker and any resulting crumbs from Activity 2 for Activity 3.

Activity 3:
1) Press down on your cracker from Activity 2 until your cracker is mostly crumbs.
2) Mark the location on your plate where you are planning on using your straw to blow on the crumbs. This is the starting location or source from where your crumbs are originating from.
3) Use your straw and blow on the crumbs in a constant pressure and direction until it forms a pile.
4) Observe the shape of the pile and take a picture of your results.
5) Using the ruler, measure the following and make notes of your findings:
a. the size of some of the crumbs on your plate
b. the distances each of those crumbs traveled from the source (their starting location)

Crumb # Crumb size (mm) Distance traveled (mm)
1
2
3
4
5

Lab Questions:
1) Include a photo of your cracker taken at the end of Activity 1.

2) At the end of Activity 1, how do the areas around the holes of the cracker compare to the other parts of the cracker?

3) What type of weathering is represented in Activity 1?

4) What is a real-world example of this type of weathering?

5) Include a photo of your cracker taken at the end of Activity 2.

6) At the end of Activity 2, how do the areas around the holes compare to the other parts of the cracker?

7) What type of weathering is represented in Activity 2?

8) What is a real-world example of this type of weathering?

9) Include a photo of your cracker taken at the end of Activity 3.

10) In Activity 3, what natural weather process does blowing through the straw represent?

11) At the end of Activity 3, what shape do the crumbs seem to form?

12) Is the pile steeper on the side where you were blowing or steeper on the far side?

13) What can this tell you about the direction of wind when a sand dune is formed?

14) Looking at your data on crumb size, which sized crumbs tended to travel the greatest distance?

15) What can the traveled distance from the source tell you about the relative force of the wind when you relate it the size of sediment particles?

Sample Solution

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