Modeling Sinkhole Formation
Materials:
12 oz. Styrofoam cup
Sand
Sugar cubes
Scouring sponge
Empty 2-L soda bottle
Scissors
Procedure:
1. Take the circular piece of the scouring sponge and place the circle in hole in the bottom of the
cup.
2. Take four sugar cubes, and place them on top of each other, in the center of the cup on top of
the sponge.
3. Carefully pour sand in the cup, filling the sides around the sugar cubes, and fill to a height so
that the sand is a thin layer over the sugar cubes. Make sure you pour carefully so that the sugar
cubes remained stacked on top of one another.
4. Take the soda bottle and fill it about one-third full of water.
5. Place the styrofoam cup in the water. After 5 minutes, empty the water from the soda bottle
and sit the cup back into the empty bottle base.
Questions:
1.
Identify what each of the following materials represented:
a. Sugar
b. Water in the soda bottle
2. At what point in the activity did the sinkhole form? Why did it occur at this point in the lab?
3. Based on this activity, what characteristics does the rock need to have in order for a sinkhole to
occur?
4. Why does the sinkhole form only where the sugar was?
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Modeling Sinkhole Formation- Teacher Preparation
Teacher Preparation- The purpose of this section is to have the teacher prepare some parts of the
procedure for the students before they arrive to minimize time required for this activity. If the teacher
would prefer that the students do the following pre-lab preparations, they can do so.
1. In the bottom of each of the foam cups, make a hole about the size of a nickel.
2. Cut pieces of scouring sponges the same size as the hole in the bottom of the cups (the students
will put these together).
3. Cut the soda bottle slightly higher than the height of the cup. Discard the top portion- the
students only need the bottom of the bottle to act as a saucer.
Materials:
12 oz. Styrofoam cup
Sand
Sugar cubes
Scouring sponge
Empty 2-L soda bottle
Scissors
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Questions Responses (these are the target answers that students should be generating):
1.
Identify what each of the following materials represented:
a. Sugar- limestone or other dissolvable rocks
b. Water in the soda bottle- groundwater (that permeates through the sponge)
2. At what point in the activity did the sinkhole form? Why did it occur at this point in the lab?
For students, this can occur at a few different times in the activity, so there are a variety of
responses
1. The sinkhole formed while the Styrofoam cup was in the water (before
removing it). The sinkhole formed because the water (groundwater) went
through the opening in the bottom of the cup, through the sponge, and
dissolved the sugar. Once the sugar began to dissolve, the sand collapsed
because a hole was created where the sugar cubes were.
2. The sinkhole formed after the water was removed from the soda bottle. The
answer should include the explanation of the dissolved sugar above, but
students should also include that it didn’t collapse until the water drained in this
case.
3. Based on this activity, what characteristics does the rock need to have in order for a sinkhole to
occur? The rock must be able to be dissolved by water.
4. Why does the sinkhole form only where the sugar was? When the water entered the cup, it
slowly dissolved the sugar, forming a cave. Sand does not dissolve in water, so a sinkhole cannot
form where the sand was.
(C) Copyright 2014 - all rights reserved www.cpalms.org