stalagmite

Image showing the six most common speleothems with labels. Enlarge to view labels.

The Witch's Finger in the Carlsbad Caverns

A stalagmite (UK: /ˈstæləɡmaɪt/, US: /stəˈlæɡmaɪt/; from the Greek σταλαγμίτης - stalagmitês, from σταλαγμίας - stalagmias, "dropping, trickling"^[1]) is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate. This stalagmite formation occurs only under certain pH conditions within the underground cavern.^[2] The corresponding formation on the ceiling of a cave is known as a stalactite. If these formations grow together, the result is known as a column.

The Hall of Giants in the Carlsbad Caverns

Stalagmites should normally not be touched, since the rock buildup is formed by minerals precipitating out of the water solution onto the old surface; skin oils can alter the surface where the mineral water will cling, thus affecting the growth of the formation. Oils and dirt from human contact can also stain the formation and change its color permanently.

Similar structures can also form in lava tubes, associated with some types of lavacicles, although the mechanism of formation is very different. Stalactites and stalagmites can also form on concrete ceilings and floors, although they form much more rapidly there than in the natural cave environment.

The largest stalagmite in the world is 62.2 metres (204 ft) high and is located in the cave of Cueva Martin Infierno, Cuba.^[3]

In the Zagros Mountains of south Iran, approximately 6 km (3.7 miles) from the ancient city of Bishapur, in the Shapur cave on the fourth of five terraces stands the 3rd century CE statue of Shapur I, second ruler of the Sassanid Empire. The statue, carved from one stalagmite, is nearly 7 m (23 ft) high.

References

External links

• The Virtual Cave: Stalagmites

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