Cave

A cave is an air- or water- filled void beneath the ground, where there is insufficient rock to prevent human access.

They can be formed by

* acidic rainwater, eroding away large of rocks such as limestone.
* lava cooling and solidifying - either in bubbles, or when the crust of a lava flow solidifies, while the still-liquid lava underneath moves on.
* waves \- on coasts, waves can pound out caves in cliffs.
* erosion from wind or water

## External links[edit]

* Limestone caves: A Result of Noah’s Flood?

* Glossary