How Is Stalagmite Formed?

What is a Stalagmite

A stalagmite is geological formation known as a speleothem or a cave formation. These are also referred to as drip formations on occasion. They are usually cone-shaped in nature, but may also develop in a plate-like shape. Stalagmites grow up from the floor of a cavern and are typically found in limestone caverns and have developed all over the world. Carlsbad Caverns National Park, which is located in southern New Mexico, has some of the most extensive speleothem formations in the United States. Stalagmites generally do not form alone. In most cases, they form in tandem with a stalactite, which is similar in nature to a stalagmite, but grows downwards from the roof or ceiling of the cavern.

The formation of a stalagmite in a natural setting is an extraordinarily long process. Growth rates for a stalagmite can be a little as seven thousandths of a millimeter a year. The formation of stalagmite requires the presence of dripping water in the cavern. Generally, rain water or water from melting snow will drip through cracks in the roof of the cavern. This water contains mineral deposits, often picked up from the limestone of the cavern. When this water drips to the cavern floor, the impact causes a tiny bit of the minerals in the water to separate out and be deposited on the cavern floor. Evaporation helps to fix the minerals in place after the water is gone. Over the course of time, the deposits grow into a visually discernible formation that is called a stalagmite.

Speleothems such as stalagmites and stalactites are usually composed of calcite or (more rarely) by aragonite and gypsum. Due to the especially long formation period that a stalagmite goes through, they can develop an internal pattern that reflects changes in the climate and environment. When a stalagmite is cut open, it reveals a number of rings around a central channel, which is hollow. The rings are made up primarily of calcite (usually), but other deposits may be present including clay. The amount of clay in a ring can be used to make educated guesses regarding now wet or dry it may have been during the development of the stalagmite. The more clay in a ring, the drier the climate had been during a given period. Stalagmites are also incredibly fragile formations that can be disrupted by something as innocent as touching them. For this reason, they are generally protected by law from any interference.