How Are Stalagmites Formed?

Stalagmites form when rain water or melted snow seeps through the cracks and rocks of caves and drips down to the floor. The mineral deposits that remain create stalagmites that grow higher as more material drips down.

Stalagmites are usually cone-shaped but may also be plate-shaped and can be found in limestone caverns all over the world. While drip formations can be formed quickly, in nature stalagmites may only grow seven thousandths of a millimeter a year, and most stalactites grow between a quarter-inch to an inch every century. Stalagmites and stalactites can therefore takes thousands of years to form.

Stalagmites and stalactites, which develop from the ceiling of caves, are usually composed of calcite and more rarely of aragonite and gypsum. Usually they grow in pairs and sometimes they even grow together to form one big column. The enormously long formation period causes internal patterns to develop that reflect climate and environmental changes. When stalagmites are cut open, they reveal rings around a hollow, central channel. The amount of clay in a ring can give clues as to how wet or dry it may have been during the development of the stalagmite. The drier the climate during a certain period, the more clay in a ring. Stalagmites are also incredibly fragile formations that can be broken with a mere touch. This is why they are generally protected by law.

Carlsbad Caverns in New Mexico are one of the many limestone caves around the globe that is world famous for its display of dripstone, as is Timpanogos Caves in Utah, Mammoth Cave in Kentucky, and Jenolan Caves and Buchan Caves in Australia.