As water meets the limestone rock it dissolves the rock and picks up minerals. When this water evaporates it leaves a hard mineral called calcium carbonate. Over hundreds of years, calcium carbonate accumulates to form stalactites, stalagmites, columns and curtains. Stalactites grow from the ceiling down.
Stalagmites grow from the floor up.
The base of the stalagmite is thicker than the top. A column is formed when a stalactite meets a stalagmite. A curtain is formed when water flows down a sloped ceiling. A thin layer of rock is formed. No sunlight reaches the interior of a cave.