Name:______________________________________________
Rock Abrasion Lab
Lab #____________
DUE:_____________
Background: As rocks are carried along by the current of a flowing stream, they tend
to wear into smaller and smoother pieces. Do all rocks undergo the same type of
change under roughly the same conditions? What happens to the rate of change
through time? In this investigation, you will study the physical changes that some rocks
undergo in a short period of time by observing them in a model situation.
Problem: What effect do hardness of rock and length of time that the rock has been
exposed to weathering have on the way rock particles are changed by physical
weathering?
Objectives: After you have completed this investigation, you should be able to:
1. State the relationship between time and the rate of abrasion for a rock of
particular type or hardness
2. Compare the effect of abrasion, in a given period of time, upon rock types of
differing hardness.
Materials:
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Container
Stopwatch
10 sugar cubes
Ruler
Data
Procedure:
1.
2.
3.
4.
5.
6.
In the top box of the chart, draw a picture of the sugar cube
Describe the cube (size in cm, shape, etc.)
Place the sugar cubes into the container.
Shake the container vigorously for 30 seconds
Draw and describe what you see in the spaces provided on the chart
Repeat steps 4-5 until all 10 observations are completed
After data table is complete proceed to questions
Data Table
Drawing
Initial Observation
0:00
1st Observation
0:30
2nd Observation
1:00
3rd Observation
1:30
4th Observation
2:00
5th Observation
2:30
6th Observation
3:00
7th Observation
3:30
8th Observation
4:00
9th Observation
4:30
10th Observation
5:00
Description
Lab Report
1. Describe the overall shape of the sugar cubes at the beginning of the exercise.
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2. Describe the overall shape of the sugar cubes at the end of the exercise.
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3. Approximately how long did it take the sugar cubes to change shape?
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4. What caused the object to change shape?
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5. Explain how this lab relates to weathering of rocks?
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6. As the objects were shaken, think about how the container was shaken. What do
you think the outcome would be if the container were shaken less vigorously?
What if the container was shaken more vigorously?
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7. A 100g of Shale were
massed, and then placed
into a container with water.
The container was shaken
for 12 minutes, every three
minutes the mass of the
shale was recorded. The
results are recorded below.
Weathering
Mass of
Time
rock
(minutes) remaining
(grams)
0
100.0 g
3
98.0 g
6
96.3 g
9
95.1 g
12
94.4 g
Construct a LINE graph
using this data
Use the data from question 7 to answer questions 8 and 9
8. How did the mass of the shale chips change over time?
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9. A) During which time period was there the greatest loss of mass from the shale
chips? ( for example from 9 to 12 minutes)
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B) Why do you suppose the greatest loss was during the time period above?
(THINK about the change in shape)
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10. A 100 grams of rock salt was places into a container with water and was shaken
for 3 minutes, after three minutes the shaker recorded the mass of the
remaining rock salt. The same procedure was repeated for 100 grams of marble
and shale. The data is shown below. Use this data to construct a BAR graph.
Type Of Rock
Mass of rock
remaining
(grams)
Rock Salt
29.3 g
Marble
98.8 g
Shale
98.0 g
Use the Data from Question 10 to answer 11-13
11. Did all three rock types weather at the same rate? If not, which one weathered at
the fastest rate?
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12. What effect does increased hardness seem to have on the amount of abrasion of
rock materials through time?
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