A seemingly timeless usage problem in geology is the difference between stalagmites and stalactites. They are both examples of mineral deposits that form in caves, or speleothems. The source of each word can be traced back to the Greek word stalassein, meaning “to drip.” This is appropriate since the source of each in nature is the dripping of mineral-rich water within caves. The difference is in their orientation: a stalactite is an icicle-shaped mineral deposit that hangs from the roof of a cavern, and a stalagmite is a conical mineral deposit that extends up from the floor of a cavern.
