Scientists Say: Stalactite and stalagmite

These are formations that occur in caves when water evaporates and leaves minerals behind


This is a chamber in Luray Caverns in Virginia. Stalactites hang from the ceiling, and stalagmites grow up from the floor.


Stalactite (noun, “Stah-LACK-tight”)

This is a mineral formation found in a cave. Water in the cave drips down, over and over in the same place. If the water evaporates before the droplet falls, the minerals in the water remain behind on the ceiling of the cave. As they solidify, they form rock. Over many years, the minerals collect into a long icicle made of rock — a stalactite. 

Stalagmite (noun, “Stah-LAG-might”)

This is another mineral formation found in caves. In this case, water drips down onto the floor, over and over on the same spot. The water evaporates, leaving any minerals in it behind. Those minerals pile up over time and solidify into rock. Over many years, they will form a rock mound on the floor — a stalagmite.

How do you remember the difference between a stalagmite and a stalactite? Stalactites cling tight to the ceiling. Stalagmites might hang from the ceiling — but they don’t.

In a sentence

Tiny worms can live inside stalactites, eating bacteria they find there.

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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