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Disappearing Rocks
How Erosion Creates Ventifacts

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Hook

Disappearing Rocks Activity

Name:						Period:			Date:

Purpose:  Erosion is one of the main reasons our Earth looks the way it does today.  
What causes erosion and how do different materials erode?

Materials

  • Rock and mineral samples--5 for each group
  • water & paper towels
  • Student Lab Sheet
  • clock or timer
  • plastic jar with lid
  • scale

    • Procedure

    Activity:
1.  Your group should have 5 rock or mineral samples.  Your teacher will tell you the 
names of each sample so you can fill in your chart below.  Weigh each one and record 
its weight before.
    
2.  Before "weathering" your rocks, predict the effect on each one.  If you don’t want to
 predict a specific weight change, rank your rocks (1 meaning it will change the most, 
5 meaning it will change the least).
    
3.  Fill your jar 1/4 of the way with water.  Place the first sample in the jar, screw the lid 
on tightly, and shake for five minutes.  Remove the sample and dab dry with a paper towel.  
Get rid of any loose sediment.  Weigh again and record the weight under weight after.  
Repeat this procedure with the other samples.  Use the observation column for any changes 
that you can readily see (size, color, or shape).
    
4.  Clean up your work area.  Complete your chart information, using the formula below to 
find your % Changes.
    
6.  Designate a spokesperson to record your % Changes for each sample on the classroom chart.  
Answer the questions in the analysis section below.

    Rock / Mineral

    Weight Before

    Weight After

    Change in Weight

    Observations

    % Change
               
               
               
               
               
               
               

    Discussions Questions/Extensions ......
    Analysis:

    1. Which rock/mineral weathered the least?

    2. Which rock/mineral weathered the most?

    3. Why would there be a difference in weathering?

    4. What in real life might be similar to the shaking in water?

    5. How might erosion affect your own backyard?

    6. Why did you use the two different-sized salt pellets? (Hint: think about the surface area)

    7. Look at the following picture and explain in your own words what has happened.


    (Picture of ice table ventifact)

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