Stalactites and stalagmites

Stalactites and stalagmites are formed by water dripping or flowing from fractures on the ceiling of a cave . They are the most common types of speleothems in caves. In caves, stalagmites grow rather slowly—0.00028–0.037 in/yr (0.007–0.929 mm/yr)—while in artificial tunnels and basements they grow much faster. Soda straw stalactites are the fastest growing (up to 1.57 in/yr, 40 mm/yr), but most fragile stalactites in caves. Soda straw stalactites form along a drop of water and continue growing down from the cave ceiling forming a tubular stalactite, which resembles a drinking straw in appearance. Their internal diameter is exactly equal to the diameter of the water drop. Formation of most stalactites is initiated as soda straws. If water flows on their external surface, they begin to grow in thickness and obtain a conical form. If a stalactite curves along its length, it is called a deflected stalactite. If its curving is known to be caused by air currents, it is called anemolite. Petal-shaped tubular stalactites composed of aragonite are called spathites. When some stalactites touch each other they form a drapery with a curtain-like appearance.

When dripping water falls down on the floor of the cave it form stalagmites, which grow up vertically from the cave floor. Any changes in the direction of the growth axis of the stalagmite are suggestive of folding of the floor of the cave during the growth of the stalagmite. If a stalagmite is small, flat and round, it is called button stalagmite. Stalagmites resembling piled-up plates with broken borders are called pile-of-plates stalagmites. Rare varieties of stalagmites are mushroom stalagmites (partly composed of mud and having a mushroom shape), mud stalagmites (formed by mud) and lily pad stalagmites (resembling a lily pad on the surface of a pond). A calcite crust (shelfstone) grows around a stalagmite if it is flooded by a cave pool and forms a candlestick.

When a stalactite touches a stalagmite it forms a column. Usually, stalactites and stalagmites in caves are formed by calcite, less frequently by aragonite, and rarely by gypsum . Fifty-four other cave minerals are known to form rare stalactites.

Sometimes calcite stalactites or stalagmites are overgrown by aragonite crystals . This is due to precipitation of calcite that raises the ratio of magnesium to calcium in the solution enough that aragonite becomes stable.

Rarely, elongated single crystals or twins of calcite are vertically oriented and look like stalactites, but in fact are not stalactites because they are not formed by dripping or flowing water and don't have hollow channels inside. These elongated crystals are formed from water films on their surface.

In some volcanic lava tube caves exist lava stalactites and stalagmites that are not speleothems because they are not composed of secondary minerals . They are primary forms of the cooling, dripping lava.

The internal structure of stalactites and stalagmites across their growth axis usually consists of concentric rings around the hollow channel. These rings contain different amounts of clay and other inclusions, and reflect drier and wetter periods. Clay rings reflect hiatuses of the growth of the sample. Stalagmites may be formed for periods ranging from a few hundreds years up to one million years. Stalactites and stalagmites in caves have such great variety of shapes, forms, and color that each of them is unique in appearance. At the same time, their growth rates are so slow that once broken, they cannot recover during a human life span of time. Thus, stalactites and stalagmites are considered natural heritage objects and are protected by law in most countries, and their collection, mining, and selling is prohibited.

See also Cave minerals and speleothems

Stalactites and Stalagmites

Resources

Stalactites and stalagmites are speleothems formed by water dripping or flowing from fractures on the ceiling of a cave.

Stalagmites grow slowly (0.00028 to 0.0366 in/yr [0.0007 to 0.929 mm/yr])in natural caves but much faster in man-made tunnels or basements. Soda straw stalactites are the fastest growing (up to 40 mm/yr.), but most fragile, stalactites in caves. Soda straw stalactites form along a drop of water and continue growing down from the cave ceiling forming a tubular stalactite, which resembles a drinking straw in appearance. Their internal diameter is exactly equal to the diameter of the water drop. Growth of most stalactites is initiated as soda straws. If water flows on their external surface, they begin to grow in thickness and obtain a conical form. If a stalactite curves along its length, it is called a deflected stalactite. If its curving is known to be caused by air currents, it is called an anemolite. Petal-shaped tubular stalactites composed of aragonite are called spathites. When some stalactites touch each other they form a drapery with a curtain like appearance.

When dripping water falls down on the floor of the cave it forms stalagmites, which grow up vertically from the cave floor. Any changes in the direction of the growth axis of the stalagmite suggests movement of the cave floor during the growth of the stalagmite. If a stalagmite is small, flat and round, it is called a button stalagmite. Stalagmites resembling piled-up plates with broken borders are called pile-of-plates stalagmites. Rare varieties of stalagmites are mushroom stalagmites (partly composed of mud and having a mushroom shape), mud stalagmites (formed by mud) and lily pad stalagmites (resembling a lily pad on the surface of a pond). A calcite crust (shelf-stone) grows around a stalagmite if it is flooded by a cave pool and forms a candlestick.

When a stalactite touches a stalagmite it forms a column. Usually, stalactites and stalagmites in caves are formed by calcite, less frequently by aragonite, and rarely by gypsum. Fifty-four other cave minerals are known to form rare stalactites. Sometimes calcite stalactites or stalagmites are overgrown by aragonite crystals. This is due to precipitation of calcite that raises the ratio of magnesium to calcium in the solution enough that aragonite becomes stable.

Rarely, elongated single crystals or twins of calcite are vertically oriented and look like stalactites, but in fact are not stalactites because they are not formed by dripping or flowing water and do not have hollow channels inside. These elongated crystals are formed from water films on their surface.

In some volcanic lava tube caves, there exist lava stalactites and stalagmites that are not speleothems because thay are not composed of secondary minerals. They are primary forms of the cooling, dripping lava.

The internal structure of stalactites and stalagmites across their growth axis usually consists of concentric rings around the hollow channel. These rings contain different amounts of clay and other inclusions, and reflect dryer and wetter periods. Clay rings reflect hiatuses of the growth of the sample. Stalagmites may be formed for periods ranging from a few hundred years up to one million years. Stalactites and stalagmites in caves have such great variety of shapes, forms, and color that almost each of them is unique in appearance. At the same time, their growth rates are so slow that once broken, they cannot recover during a human life span of time. Thus, stalactites and stalagmites are considered natural heritage objects and are protected by law in most countries, and their collection, mining, and selling is prohibited.

See also Mineralogy.

Resources

BOOKS

Ford, D.C. and P. Williams. Karst Hydrogeology &Geomorphology. New York: Wiley, 2006.

Hildreth-Werker, V., and J.C. Werker. Cave Conservation and Restoration. Huntsville, Alabama: National Speleological Society, 2006.

Yavor Shopov

Stalactites and stalagmites

Stalactites and stalagmites are speleothems formed by water dripping or flowing from fractures on the ceiling of a cave .

In caves, stalagmites grow rather slowly (0.00028-0.0366 in/yr [0.007-0.929 mm/yr]), while in artificial tunnels and basements they grow much faster. Soda straw stalactites are the fastest growing (up to 40 mm/yr.), but most fragile stalactites in caves. Soda straw stalactites form along a drop of water and continue growing down from the cave ceiling forming a tubular stalactite, which resembles a drinking straw in appearance. Their internal diameter is exactly equal to the diameter of the water drop. Growth of most stalactites is initiated as soda straws. If water flows on their external surface, they begin to grow in thickness and obtain a conical form. If a stalactite curves along its length, it is called deflected stalactite. If its curving is known to be caused by air currents, it is called anemolite. Petal-shaped tubular stalactites composed of aragonite are called spathites. When some stalactites touch each other they form a drapery with a curtain-like appearance.

When dripping water falls down on the floor of the cave it form stalagmites, which grow up vertically from the cave floor. Any changes in the direction of the growth axis of the stalagmite are suggestive of folding of the floor of the cave during the growth of the stalagmite. If a stalagmite is small, flat and round, it is called button stalagmite. Stalagmites resembling piled-up plates with broken borders are called pile-of-plates stalagmites. Rare varieties of stalagmites are mushroom stalagmites (partly composed of mud and having mushroom shape), mud stalagmites (formed by mud) and lily pad stalagmites (resembling a lily pad on the surface of a pond). A calcite crust (shelfstone) grows around a stalagmite if it is flooded by a cave pool and forms a candlestick.

When a stalactite touches a stalagmite it forms a column. Usually, stalactites and stalagmites in caves are formed by calcite, less frequently by aragonite, and rarely by gypsum. Fifty-four other cave minerals are known to form rare stalactites. Sometimes calcite stalactites or stalagmites are overgrown by aragonite crystals. This is due to precipitation of calcite that raises the ratio of magnesium to calcium in the solution enough that aragonite becomes stable.

Rarely, elongated single crystals or twins of calcite are vertically oriented and look like stalactites, but in fact are not stalactites because they are not formed by dripping or flowing water and do not have hollow channels inside. These elongsted crystals are formed from water films on their surface.

In some volcanic lava tube caves exist lava stalactites and stalagmites that are not speleothems because thay are not composed of secondary minerals. They are primary forms of the cooling, dripping lava.

The internal structure of stalactites and stalagmites across their growth axis usually consists of concentric rings around the hollow channel. These rings contain different amounts of clay and other inclusions, and reflect dryer and wetter periods. Clay rings reflect hiatuses of the growth of the sample. Stalagmites may be formed for periods ranging from few hundreds years up to one million years. Stalactites and stalagmites in caves have such great variety of shapes, forms, and color that almost each of them is unique in appearance. At the same time, their growth rates are so slow that once broken, they cannot recover during a human life span of time. Thus, stalactites and stalagmites are considered natural heritage objects and are protected by law in most countries, and their collection, mining , and selling is prohibited.

See also Mineralogy.

Resources

books

Taylor, Michael Ray, and Ronal C. Kerbo. Caves: ExploringHidden Realms. National Geographic, 2001.

periodicals

Shopov Y.Y. "Genetic Classification of Cave Minerals." Proceedings of X-th International Congress of Speleology, (1989):101-105.

Yavor Shopov

stalactite.
1. System of corbelling, called muqarna, really brick squinches (see dome) and vaults with the soffits elaborately carved to resemble a series of stalactites, in Islamic, particularly Moorish, architecture.

2. Stone or stucco forms resembling stalactites or icicles, called congelation, found in grottoes.

stalactite Elongated body of dripstone descending from the roof of a cave in a karst environment. It is produced by calcite precipitation as excess carbon dioxide diffuses from water droplets entering a cave environment.