Making Caves: How Solution Caves Form

Activity Source:

Adapted with permission by National Park Service

Caves form through a variety of natural processes depending on their local geology and climate. Flowing lava, melting ice, dissolving rock, and crashing waves are the major processes that form these wondrous environments. In this activity, students will observe a model of how the most common type of cave — solution caves — form.

Materials

Per student or small group:
• 4 ounces of modeling clay
• Sugar cubes (3-6 per cave)
• See-through bowl (cutting the top off a 2-liter bottle works well)
• Toothpick
• Spray bottle with warm water
• Lined paper
• Pen or pencil

Procedure

1. Organize the sugar cubes into a half pyramid along the bottom of the bowl, making sure the sugar is pressed up against one side of the bowl.
2. Seal the cubes tightly against the side of the bowl with the modeling clay, making sure there are no gaps. The clay layer should be about 1/8 inch thick. The sugar cubes that are pressed up against the glass should remain visible. This will act as a window into your cave.
3. Poke holes through the top of the clay with the toothpick, making sure that the holes go all the way through to the sugar cubes and are large enough for water to flow through them.
4. Spray the top of the cave with the warm water from the spray bottle. Continue spraying until the sugar cubes either are no longer in their original shape or have completely dissolved.
5. As the water seeps through the clay and into the sugar cubes, record your observations.
6. Draw a picture or describe what your cave looked like when finished.

Discussion

• What did the sugar cubes represent? What did the clay represent? Describe in your own words how this model simulated the formation of caves.
• How does observing the process of caves forming, or the caves and formations that result, inspire you?
• What words would you use to describe caves or how they form to someone who has never seen one?

NGSS Connections

Crosscutting Concepts

- Cause and effect

- Structure and function

Science and Engineering Practices

- Asking questions and defining problems

- Engaging in argument from evidence

- Developing and using models

Disciplinary Core Ideas

- Life Science:
• Interdependent relationships in ecosystems