Why do some caves grow stalactites and stalagmites?
Quick Answer
They form when mineral-rich water drips or falls in caves and leaves behind calcium carbonate. Over time, deposits hanging from the ceiling become stalactites, and those on the floor become stalagmites.
The Full Story
Rainwater absorbs carbon dioxide from soil, making weak carbonic acid that can dissolve limestone. When that water enters a cave, it can lose carbon dioxide to the air and precipitate calcite, building dripstone formations. Stalactites hang from the ceiling because deposits form where the water drops leave mineral residue. Stalagmites rise from the floor where falling drops land, and if both keep growing they can eventually join into a column.
Key Facts
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