STALACTITE encyclopedia topics

STALACTITE - 5 reference results

stalactite ornament, type of ornament characteristic of Islamic architecture. Generally executed in wood or in plaster over a wood or brick base, it consists of little vertical polygonal or curved niches rising and projecting in rows above one another in such a way as to create a general prismatic, corbeled form. Ingenious and intricate compositions of these elements are possible, and such purely geometric decoration was particularly acceptable to the Muslims in view of the Qur'an's prohibition of the use of natural forms. The primary use of stalactites was to form pendentives in the corners of a square room to receive the base of a circular dome, though this use was relatively infrequent in the Spanish Muslim style. Absent from the earlier Muslim buildings, they came into general use everywhere early in the 12th cent., forming cornices and the caps of posts and columns, decorating the heads of niches, and supporting the projecting balconies of minarets. In the interior of the Alhambra at Granada, Spain (13th-14th cent.), stalactites appear in particularly beautiful arrangements, especially in the decoration of arches and in the fantastic honeycombed ceiling vaults.

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stalactite and stalagmite

stalactite and stalagmite, mineral forms often found in caves; sometimes collectively called dripstone. A stalactite is an icicle-shaped mass of calcite attached to the roof of a limestone cavern. Groundwater trickling through cracks in the roofs of such caverns contains dissolved calcium bicarbonate. When a drop of water comes in contact with the air of the cavern, some of the calcium bicarbonate is transformed into calcium carbonate, which is precipitated out of the water solution and forms a ring of calcite on the roof of the cavern. By repetition of this process the length and thickness of the stalactite is increased. A stalagmite is a cone of calcite rising from the floor of a cavern. Stalagmites and stalactites are often found in pairs, the stalagmite being formed as a result of further evaporation and precipitation from solution after the trickle of water falls from the stalactite. Stalactites and stalagmites often meet each other to form solid pillars. Curtains of dripstone sometimes form when water drips from the ceiling of a cave along joint planes. Since stalactites, stalagmites, and curtains of dripstone form only in the presence of air, their existence in a cave indicates that the cave was above the water table while the dripstone was forming. The many colors often seen in these formations are caused by the presence of impurities. Celebrated caverns that owe much of their beauty to their stalactites and stalagmites are Mammoth Cave, Ky.; the Luray Caverns, Va.; and the Carlsbad Caverns, N.Mex. Onyx marble (Mexican onyx, Egyptian alabaster, or Oriental alabaster), used as a decorative stone, is derived from stalagmites and stalactites, as well as from similar deposits.

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Licensed from Columbia University Press

stalactite work

or muqarnas

Honeycomb-like Islamic architectural ornamentation formed by the intricate corbeling (see corbel) of squinches (see Byzantine architecture), brackets, and inverted pyramids in overlapping tiers. It appeared in the early 12th century throughout the Islamic world; a frequent use was to overlay the transitional zone between domes and their supports. It reached its highest development in the 14th–15th century, when it became the usual decoration for door heads, niches, and the bracketing under cornices and minaret galleries. Rich examples are found in the Alhambra and other Moorish works in Spain.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

stalactite and stalagmite

Elongated forms of various minerals deposited from solution by slowly dripping water. A stalactite hangs like an icicle from the ceiling or side of a cavern. A stalagmite rises from the floor of a cavern. The two are not necessarily paired; when they are, continual elongation of one or both may eventually join them into a column. The dominant mineral in such deposits is calcite (calcium carbonate), and the largest displays are formed in caves of limestone and dolomite.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.