Caves and Caverns

A cave is a hollow space underground that is big enough for a person to enter. Caves form over thousands of years as water dissolves rock. A cavern is a very large cave. Many caves have amazing rock formations inside them.

How Caves Form

Most caves form in a type of rock called limestone. Rainwater mixes with a gas in the soil and becomes slightly acidic. This acidic water seeps into cracks in the rock. Over time, it dissolves the rock and makes bigger and bigger spaces underground.

What Is Inside a Cave

Caves can have beautiful rock shapes. Stalactites hang from the ceiling like icicles. Stalagmites grow up from the floor. When the two meet, they form a column. Some caves have underground rivers and lakes. Bats and other animals live in caves too.

Fun Facts

• Mammoth Cave in Kentucky is the longest cave system in the world, with over 400 miles explored.
• Some caves have crystals that are taller than a person.
• Cave paintings made by ancient people have been found in caves in France and Spain.

Did You Know?

A stalactite grows only about one inch every hundred years, so a long one could be thousands of years old!