Stalagmite

A stalagmite is a fascinating rock formation that grows upward from the floor of a cave. It forms when mineral-rich water drips from the ceiling of a cave and then builds up on the floor over many years. These formations are usually made of calcium carbonate, but they can also be created from other materials like lava, mud, peat, pitch, sand, sinter, and even the crystallized urine of pack rats.

Image showing the six most common speleothems

Stalagmites are often found in caves alongside their “siblings,” the stalactites, which hang down from the ceiling. While stalactites grow down, stalagmites grow up, and sometimes they meet in the middle to form a column. These formations tell us a lot about the history of the Earth and the movements of water deep underground.

Scientists and explorers study stalagmites to learn about past climates because the layers in these rocks can show how much rain fell and what the temperatures were thousands of years ago. They are important for understanding our planet’s history and the processes that shape caves and other natural wonders.

Formation and type

Calthemite stalagmite growing on a floor beneath a concrete structure

Stalagmites are rock formations that rise from the floor of caves. The most common type forms in limestone caves through the buildup of calcium carbonate from dripping water. These formations need certain conditions, like the right pH level, to develop. When stalactites hanging from the ceiling grow long enough, they can connect with stalagmites on the floor to form columns.

Other types of stalagmites include those formed from lava in volcanic tubes, which create quickly as drops of cooling lava pile up. There are also ice stalagmites that form when freezing water drips into caves. In addition, similar formations can appear on concrete structures due to the leaching of calcium from the material. Each type of stalagmite forms in unique ways but all involve the gradual buildup of material on a surface.

Records

The largest known stalagmite in the world rises over 70 meters (230 feet) and is found in Sơn Đoòng Cave in Vietnam.

In the Zagros Mountains of Iran, near the ancient city of Bishapur, stands a nearly 7-meter (23-foot) tall statue carved from a single stalagmite. This statue represents Shapur I, who ruled the Sassanid Empire in the 3rd century.