Stalagmite

A stalagmite is a rock that grows upward from the floor of a cave, one drip at a time, at about one centimetre per century. It is the only rock that is taller now than when you started reading this sentence, by roughly a billionth of a millimetre.^[1]

Stalagmites grow up from the floor; stalactites hang down from the ceiling. The traditional way to remember this is that stalactites hold on “tight”, while stalagmites “might” one day reach them. After 40,000 years most stalagmites have stopped answering when this is brought up.

Growth

In 1902 a team of geologists set out to watch a stalagmite meet the stalactite above it, across a gap of just over a centimetre. Their children took over in 1931, their grandchildren in 1967, and their great-grandchildren in 1994. On 12 March 2019, at 3:14 pm, the two finally touched. Witnesses described the moment as “a drip”. The column has done nothing since, which experts say was the plan all along.^[2]

Classification

Under the Standard of Lumps, a stalagmite is a boulder that grew upwards instead of outwards, in the way that a skyscraper is a house that kept adding upstairs. A stalagmite more than ten metres tall may apply to be called a column, but must first prove it is not standing on another stalagmite.^[3]

See also

• Rock (rock) – a stalagmite with no ambitions
• Skyscraper – also grows upward, faster
• Dew – the same drip, outdoors, in less of a hurry

References

1. Drip, D. et al. (1902–2019). “Are They Touching Yet?”. Field notes, four generations.
2. Limestone, L. (2011). Up, Slowly. Calcite Press. Vol. 1 of an expected 400.
3. International Lump Council (1971). “Columns: Guidance for Applicants”.