Name: ________________________
Due Date: _____________________
Per: ________
40 minutes
Rock Abrasion
Purpose: At the end of this activity, you should be able to identify the effects of
moving water on different rock types.
Materials: 100 grams of presoaked marble chips, 100 grams of presoaked
sandstone, 100 grams of Rock Salt, container for shaking, screen for draining the
rocks, beaker for measuring water, electronic balance
Objectives:



Determine the effects of moving water on rocks.
Describe the appearance of weathered rocks.
Infer what factors may influence the rate of weathering.
Introduction:
Running water wears down the surface of the Earth. As the current of a
flowing stream carries rocks downstream, they tend to wear into smaller and
smaller pieces. Rock fragments have their edges physically rounded as they are
abraded against each other and rolled and bounced along the stream channel.
Running water may also dissolve soluble minerals in the rocks.
Do all rocks undergo the same type of change under roughly the same
conditions? What happens to the rate of weathering 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. The model
represented by this lab will demonstrate some factors that control the weathering
of particles in running water.
Vocabulary: Prior to starting the lab, write out definitions to the following terms:
Abrasion - ________________________________________________________
_________________________________________________________________
Sediment - _______________________________________________________
_________________________________________________________________
Soluble - _________________________________________________________
_________________________________________________________________
VVS Earth Science
Weathering
Rock Abrasion
Page 1 of 4
Procedures:
Effects of weathering on marble:
1. Retrieve a handful of presoaked marble chips (at least 100 grams).
a. Dry the pieces well with paper towels.
b. Find the total mass to the nearest 0.1 gram.
c. Record in data table 1 at Time = 0 (no shaking has taken place yet).
2. Place marble chips into the plastic container. Add about 500 mL of water.
3. Tightly cap the container and shake vigorously for three (3) minutes.
4. Drain the marble chips through a screen and dry them with paper towels.
5. Find the new mass. Record in data table 1 at Time = 3.
6. Return the marble chips to the container and repeat the process 2 more
times (shaking for 3 min, drying, massing, recording data) until the chips
have been shaken a total of 9 minutes.
7. Use the following equation to find the % remaining after each 3 minute
interval:
% Remaining = (New Mass / Mass @ Time = 0) x 100
8. When done with your rocks, throw them away.
Effects of weathering on sandstone:
1. Obtain about 100 grams of sandstone.
2. Repeat the same procedures as you did for the marble chips.
Effects of weathering on rock salt:
1. Obtain about 100 grams of rock salt.
2. Repeat the same procedures as you did for the marble chips and
sandstone.
Graphing Data:
1. Plot the data for Percent Mass Remaining (dependent variable) versus Time
(independent variable) for all 3 rocks.
2. Be sure to properly set up the scales for both axes and label them. You
may not need to use every line provided on the graph paper.
3. Draw a line graph for each rock and label them or create a color-coded key.
VVS Earth Science
Weathering
Rock Abrasion
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Data Table:
Weathering
Time
(minutes)
Mass of
Marble
(grams)
0
Percent (%)
Marble
Remaining
100
Mass of
Sandstone
(grams)
Percent (%)
Sandstone
Remaining
Mass of
Rock Salt
(grams)
100
Percent (%)
Rock Salt
Remaining
100
3
6
9
Conclusions:
1. Why did we need to soak the rock chips before conducting the
investigation? ________________________________________________
____________________________________________________________
2. What is the relationship between shaking time and mass (and shape) of the
rocks? ______________________________________________________
____________________________________________________________
3. What other factors could have affected your results? (What are possible
sources of error?) _____________________________________________
____________________________________________________________
4. How would the results of your investigation be affected if you used pieces of
a harder rock such as quartzite? __________________________________
____________________________________________________________
5. What property of the rock salt made it lose mass so quickly?
_____________________________________________________________________
_____________________________________________________________________
VVS Earth Science
Weathering
Rock Abrasion
Page 3 of 4
The Effect of Time on Weathering
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Weathering
Rock Abrasion
Page 4 of 4