How does dripping water deposit calcite inside caves?

Calcite is deposited inside caves through a process driven by the movement of water and changes in chemical equilibrium. As rainwater infiltrates the soil, it absorbs carbon dioxide to form a dilute solution of carbonic acid. This acidic water dissolves calcite as it percolates through limestone bedrock.1

When this mineral-rich water emerges from a joint in a cave ceiling, it hangs as a pendant drop. Upon exposure to the cave atmosphere, the water loses carbon dioxide, which reduces its ability to hold calcium carbonate in solution, causing some of it to precipitate.12

This process creates various speleothems:
* Stalactites: As drops hang from the ceiling, they leave behind a ring of calcite. Over time, these rings build downward into icicle-like structures.12
* Stalagmites: When the remaining water drips onto the cave floor, the mineral matter precipitates further, building upward from the ground.12
* Flowstone: Water flowing along walls or ledges leaves behind sheets of calcite, forming massive deposits.1

Essentially, the infiltrating water acts as a pump, removing calcite from the surface bedrock and redepositing it within the stable environment of the cave.1