Caves and Sinkholes

What You'll Learn

Sinkholes form when underground limestone dissolves, leaving a cavity that collapses. They are common in areas with karst topography where water slowly dissolves the bedrock.

Key Words

mineral
climate

Materials Needed

food coloring
clear container
rocks
sand

Safety First

Work in a well-ventilated area when using vinegar or other strong-smelling substances.
Dispose of materials properly after the experiment.
Handle glass items carefully to avoid breakage.

Steps

Step 1 — Read

Look at the vocabulary words and write a definition for each in your own words.

Step 2 — Do

Test rock hardness using Mohs scale: try scratching rocks with your fingernail, a penny, and a nail. Rank them from softest to hardest.

Step 3 — Observe

Compare the before and after states.

Step 4 — Record

Write your conclusion: did the results match your hypothesis? What would you change next time?

Check Your Understanding

Question 1

1 of 3

What causes ocean tides?