Final answer:
Stalactites are formations that hang from the ceiling of limestone caves, while stalagmites form on the cave floor. They are created by the deposition of calcium carbonate when groundwater seeps into the cave and water evaporates, causing the CaCO3 to precipitate and form these structures.
Step-by-step explanation:
Stalactites are cave formations that hang from the ceiling of limestone caves. They are formed by the deposition of calcium carbonate when groundwater containing atmospheric CO2 seeps into the cave. As water evaporates from the solution, a circular layer of solid CaCO3 is deposited, which eventually grows down from the ceiling and forms a stalactite. Stalagmites, on the other hand, are formed when water carrying calcium carbonate drips from the stalactites and accumulates on the floor of the cave, causing the CaCO3 to precipitate and form a spire that grows up.