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crayon rock cycle

The rock cycle describes the continuous processes that break down and form the three main rocks- igneous,
sedimentary and metamorphic. Igneous rock is formed by the cooling and hardening of magma. Sedimentary
rock is formed through weathering and erosion, deposition, compaction, and cementation of rock fragments.
Metamorphic rock is formed by great heat and pressure on a rock that causes it to change form into a
metamorphic rock.
Problem Statement: How can crayons be used to model the rock cycle?
Making Sedimentary Rock-Part 1
In nature, rocks are broken down by the forces of nature. In this simulation the crayons represent rocks and
the coin represents weathering agents (wind, sun, ice, rain) that cause rocks to break down into smaller
1. Each partner needs to weather his/her rock. In other words, use a coin to shave your crayons into small
pieces. Collect the shavings on a paper towel. Be as neat as you can.
a. What do the different colored crayons represent?
b. What happens to the rock when it is weathered?
c. Are the fragments all the same size or shape? Explain.
Once rock fragments have been created, they are usually moved (eroded) by some force of nature like gravity
and dropped in a new location (deposition). Here you will act as a depositional force.
2. Each lab partner, in turn, should move (erode) and lay down (deposit) the rock fragments in a neat pile
in the center of the foil. Set each new pile on top of the previous ones.
a. What happened to your sediments during erosion and deposition?
This part of the simulation requires you to understand the cementation process. Spaces between the
fragments are reduced in size by pressure (compaction) and filled with the cementing agents (cementation).
This simulation will not add cementing agents. It will only simulate compaction. The compaction process
occurs as sediment layers are continually covered by new layers of sediments. The low layers become
compacted by the weight of the new layers above.
3. Carefully fold the loose layers of crayon shavings inside the aluminum foil creating a packet.
4. Press the packet between the palms of your hands and press firmly. You can also place the packet on
the table, put you palms of your hands on the top of the packet, and press down using a textbook. This
will compact your weathered and eroded rocks (crayon shavings).
a. Describe the compactions. Are the sediments tightly or loosely compacted?
Making Metamorphic Rock-Part 2
As the rocks are pushed deeper into the Earth’s crust, pressure and temperature increase. Metamorphic rock
may become contorted in appearance and flow like plastic material in response to the heat and pressure that
is cause by the overlying rocks.
5. Take your folded packet and open it. Place it for 15 seconds on a hot plate. Then “taco” your foil to
apply pressure.
a. Do you see any layers? Describe.
b. In nature, what is causing the increase in temperature and pressure?
Making Igneous Rock – Part 3
Igneous rocks form deep within the earth. They originate in magma chambers in solid rock.
6. Take your remaining crayon rock in the aluminum foil boat and place it on a hot plate to melt the
crayon. The cooling process will then form igneous rock.
a. Describe what the melted “rock” (magma) looked like.
b. Would your igneous rock be considered an intrusive or extrusive rock? Explain.
Complete the chart below by using the terms from your output and 22.3 Rock and Rock Cycle Reading
Process of the lab activity
Shaving down of crayons
Transferring of the sediment onto
the sheet of tin foil
Applying pressure to pile of crayon
Setting the rock in the tin foil on
hot plate and then applying
Setting the rock in the tin foil on
the hot plate to melt
Cooling of the melted crayons
Process of the rock cycle
Type of Rock Created
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