1. The Federal Cave Resource Protection Act of 1988 defines a cave as "any naturally occurring void, cavity, recess, or system of interconnected passageways beneath the surface of the earth." Caves are also called caverns.
2. Caves exist all over the world and come in many sizes and shapes. Some caves have an entrance at the earth’s surface, but many times they do not.
3. Some caves are filled with air and others are filled with water. Caves often contain sand, mud, clay, silt, or other sediment.
4 .When caves are discovered it is important they are protected. Their environment is fragile and can easily be destroyed when lighting, air, bacteria, and people enter their chambers.
5. Many things can be learned from cave exploration and study. They have rare plants and animals. They also have very distinctive mineral formations, fossils and artifacts.
6. Caves record the Earth’s history and climate.
7. The mineral deposits that hang from the ceiling of a cave like an icicle are know as stalactites. The stalagmite is on the floor of the caves and grows up. They grow in pairs as water drops down the stalactite making it grow downward, and as the drops fall on the floor they begin to build upward forming the stalagmite.
8. The eye can never adjust to total darkness, because there needs to be some light in order for any living thing to see. Therefore, the animals that live in caves have adapted to the darkness by having extraordinary hearing or antenna that help them survive.
9. The greatest and longest cave system in the world is at Mammoth Cave Park in Kentucky, USA. It has about 367 miles (591 kilometers) of cave system. The deepest cave is Voronya Cave in Abkhazia, Georgia with a depth of 7,188 feet (2,191 meters). The largest cave in the world is the Sarawak Chamber in Sarawak, Malaysia. Its floor area is so big it could hold ten 747 jets nose to tail.
10. Many people like to explore caves. These people are known as spelunkers.