Why do stalactites and stalagmites grow in caves?
Quick Answer
They grow because mineral-rich water drips through cave ceilings and leaves behind calcite when carbon dioxide escapes. Over time, tiny deposits build into large cave formations.
The Full Story
In limestone caves, groundwater can carry dissolved calcium bicarbonate. When a drop hangs from the ceiling or lands on the floor, it loses carbon dioxide and precipitates calcite, the mineral form of calcium carbonate. Deposits hanging from the ceiling are stalactites, while those building upward from the floor are stalagmites. If they meet, they form a column. Cave decorations can take thousands of years to form, and their growth rates depend on drip frequency, water chemistry, and temperature.
Key Facts
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