Rock Formation Demonstration (SEPUP Activity 19)
Julie Barker
Revised from Julia Stevens “How Does Sandstone Get Its Stripes? And The Society for Mining,
Metallurgy, and Exploration, Inc. “Sedimentary Rock Activities”
Target Concept: Sedimentary Rock Formation
8-3.4: Explain how igneous, metamorphic, and sedimentary rocks are interrelated in the rock
cycle.
8-2.2: Summarize how scientists study Earth’s past environment and diverse life-forms by
examining different types of fossils (including molds, casts, petrified fossils, preserved and
carbonized remains of plants and animals, and trace fossils).
Materials
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Large container (personally used a pretzel jug)

Smaller glass jar
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Sand

Rice

Golf Ball

Large rocks

Small Rocks

Sand

Dirt (keep this to a minimum otherwise water is too foggy)

Shells
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Rocks of Petra Activity Sheet
Procedures
1. Start by showing students photos of sedimentary rock that has many layers. Ask them to
write down what they observe about the photographs.
2. Have the students share what they wrote down with the class.
3. Prompt discussion by asking how they students think that the layers are formed. Suggest
(if a student has not done so) that at one point in time these rocks were once underwater.
4. Next show the students the pretzel jug in which you placed the two rock sizes, sand, dirt,
and water. Ask the students what will happen if you invert the jug and then right it again.
Will the heavier items be on top or the bottom? (bottom) Why? (they are heaviest)
5. Prompt the students by asking them how often do streams, lakes, and rivers get inverted?
(never) How can they mix? (currents, waves, tides, earthquake, plate tectonics, etc.)
What does this create? (energy)
6. Ask the students what will happen if you apply energy to the jug by swirling it around,
what will be on the bottom? (students will usually guess the large rocks, again because
they are heaviest… however the heaviest items will move to the top). Show the students
how layers were formed with the heaviest items on top. Ask why they think this
happened.
7. To make it more clear, in the smaller glass jar place the rice, sand, and golf ball. Push the
golf ball to the center of the sand/rice mixture. Shake the jar and the golf ball will come
to the surface.
8. Discuss with the students the idea that energy acts on the small particles which can fall
into the space between the large particles and push them to the surface.
9. Next ask how these layers shown in the pretzel jug become the rocks shown on the
screen? (over millions of years they harden to form rock). What type of rock formation is
this? What is another work for sand, dirt, stones? (sediment, so this is sedimentary rock)
10. To start to introduce fossils you can then show them a shell and ask where would it fall
within this layering system? (between the small stones and sand maybe) What would
happen to it once these layers become rock? (it will form a fossil) What are fossils made
of? (minerals). Show some pictures of fossilized shells.
11. Revisit the pictures that were shown at the beginning. Ask the students again how the
layers were formed. Make sure they understand that the top layer was made from the
heaviest materials and the bottom layer was made from the lightest materials.
12. Explain that sedimentary rock is only one type and that the reading will discuss the other
main rock types.
13. Assign the rocks of Petra activity sheet for homework to reinforce the ideas discussed in
the demonstration.
The Rocks of Petra
Name:____________________________________
Instructions: Before Answering these questions read pages 205-207 in your
Glencoe South Carolina Science book. Observe the following picture and answer
the questions.
Petra is an ancient city in the desert of
Jordan and is considered one of the new
wonders of the world. The site was
completely unknown until 1812 when it was
discovered by a Swiss explorer. Excavations
have shown that is was the ability of the
ancient people to control the water supply
that led to the rise of this desert city. The
history of the beginning of this city remains
unknown.
1. Describe the pattern in the rocks. What do you think might have caused this?
2. What types of rocks do you think were used to make these buildings? Why?