Rock Weathering
Cody Jorgensen
3rd Grade Teacher
Valley View School
Adams County, Colorado
Grades: 3-5
Objectives:
Students will be able to explain what weathering is and how it affects rocks.
Students will be able to explain what causes weathering.
Students will be able to examine a panel of rock art (petroglyphs) and determine if
weathering is harming the petroglyph.
Length of lesson: 3-5 days
1. Begin by asking the students if they think that rocks last forever. They will most likely
answer yes. Explain to them that rocks do not last forever because they go through a
process called weathering.
Give them the definition of weathering: when rocks break down and change over a long
period of time from being exposed to many different processes. Remind them that, while
the weather might influence rocks breaking into smaller pieces, scientists also call the
rock decay—like a cavity in your tooth that’s hard, but can decay over time because
different factors break it into smaller and smaller pieces. Explain that one way this occurs
in rocks is through water that breaks down the rocks by a chemical reaction which
loosens the bonds holding the rocks together. This weakens the rock. The rock begins to
break down into smaller pieces over a long period of time.
2. Show them pictures of rocks and old gravestones that have obvious weathering
occurring. Gravestones are a good example because the kids can see how the words on
the gravestones are disappearing because the rock is decaying.
3. In order to give the students a more concrete example of weathering do one, or both, of
the following experiments:
Experiment 1
Materials needed:
Six jars
Carbonated water or vinegar
Samples of limestone
Samples of sandstone
Samples of shale
*Fill three of the jars with tap water and the other three jars with carbonated water or
vinegar.
*Put a piece of limestone in one tap water jar and one carbonated water/vinegar jar.
*Put a piece of sandstone in one tap water jar and one carbonated water/vinegar jar.
*Put a piece of shale in one tap water jar and one carbonated water/vinegar jar.
*Let the jars sit for a few days and observe what happens to the rocks. The rocks in the
carbonated water/vinegar jars will break down much more quickly than the ones in the
tap water because the carbonated water/vinegar is mimicking acidic water which breaks
down rocks and causes weathering.
*Have the students observe and record their observations over the few days that the rocks
sit in the jars.
*Discuss with the students that this is how weathering occurs. The water from rain and
snow becomes acidic and begins to break down rocks over long periods of time.
Experiment 2
Materials needed:
Jars for each group
Effervescent tablets such as Alka-Seltzer
*This experiment speeds up the process of showing students how weathering occurs.
*Have the students place a tablet in a jar of water and observe how the tablet breaks
down from the water.
*Explain that this is what happens to rocks, but in a much slower process, when
weathering occurs.
4. Now that the students have learned what weathering is and some of what causes it,
teach the students why it is important to study weathering. Explain to the students that
physical geographers and geologists are people who study the earth and how it changes.
Tell them that some physical geographers and geologists study rocks and weathering.
5. Explain to the students what rock art (petroglyphs) are and show them pictures of
petroglpyhs.
Petroglyphs are drawings that have been carved into rocks by ancient people.
Discuss with the students why petroglyphs are important to history and the cultures they
come from. Then tell them that because petroglyphs are old and were carved on rocks
that have weathering occurring, some petroglyphs are in danger of disappearing like the
words on the gravestones they saw.
6. Tell the students that some of the scientists who study rocks, specifically study rocks
that have petroglyphs on them so that they can determine which petroglyphs are in the
most danger from the weathering occurring on the rock. They will analyze (study) the
rock to see what sort of weathering is occurring and to see if the petroglyph is starting to
disappear from loss of the weathered rock.
7. Tell the students that today they are going to be earth scientists studying panels (rocks)
that have petroglyphs on them to determine if the petroglyph is in danger of disappearing.
Give them the Rock Art Weathering form (see attached worksheets) and explain how to
fill the form out while showing them a picture with an example of rock art. You may
need to do a few examples with them before giving them their own rock art picture to
analyze.
Rock Art Weathering Activity
*Break the students into groups and give each group a picture of rock art to analyze.
Make sure the picture shows the actual rock and not just the petroglyph because they are
looking at the weathering that is occurring on the entire rock, not just where the art is.
*First, they need to draw a picture of their rock and the petroglyph in the box on page
one.
*Then, they will answer each question on page two by circling the response for each
question. I have given the terms that a physical geographer or geologist would use in
bold, and then asked a question to explain what that word means for each row. This is so
that you may teach the scientific word along with what the word means.
*Once they have completed page one and two, have them give their final results on the
last page. On this page they will use their analysis from page 2 to determine if their panel
of rock art is in danger of disappearing from weathering. If they decide that it is in
danger, have them brainstorm a way that they think the rock art could be saved from
disappearing.
Rock Art Weathering
Name________________________________
Date________________
Draw a picture of your panel. Make sure to include any cracks you see in
the rock.
Now let’s see if your panel is in danger from weathering!
Fissures
Does your panel
have cracks in it?
Many cracks
Some cracks
No cracks
Plants growing
on my panel
Plants growing
near my panel
No plants
growing on or
near my panel
Many flakes
missing
Some flakes
missing
No flakes
missing
Large piece
missing
Small piece
missing
No pieces
missing
Large amount of
moss
Some moss
No moss
Plant Growth
Are there plants
growing on or
near your panel?
Flaking
Are there flakes
of rock missing
from your panel?
Undercutting
Are there large
pieces of rock
missing from the
bottom of your
panel?
Lithobionts
Is there moss or
lichens growing
on your panel?
Graffiti
Does your panel
have graffiti on
it?
Large amounts of
Some graffiti
graffiti
No graffiti
My Results
Look at your answers from page 2 and decide if your panel is in danger of
disappearing from weathering.
How many happy faces do you have? _______________
How many middle faces do you have? _______________
How many sad faces do you have? _________________
 If you have 5 or 6 happy faces then it is not in danger of disappearing.
 If you have 3 or 4 happy faces then it is somewhat in danger of
disappearing.
 If you have 0-2 happy faces and mostly middle or sad faces, then it is
in a lot of danger of disappearing.
Fill in the blank with one of the underlined terms above.
I found that my rock art panel is _____________________________danger
of disappearing from weathering.
If your panel is somewhat in danger or in a lot of danger of disappearing,
how do you think you can save your panel?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________