This video segment adapted from NOVA chronicles the discoveries that led to a radical new theory in which living organisms, not just geological processes, play an active role in cave formation. [5:42]

Take a look at the inside of caves. Recognize stalactites, stalagmites and other features of caves.

Companion to a PBS program in the Nova series. There are wonderful photos of the Lechuguilla cave system in New Mexico, and some new information on how caves are formed.

Facts and resources for kids regarding the Cave of the Winds.

The National Caves Association provides a directory of caves in the United States. This directory is in alphabetical order by state. It also answers frequently asked questions and provides helpful links.

What is the highest elevation on earth? How about the driest place on earth? Do you know where the greatest earthquake took place? Let Extreme Science take you to these places and other extreme places around the world.