stalactite and stalagmite

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.

* * *

▪ mineral formation
 elongated forms of various minerals deposited from solution by slowly dripping water. A stalactite hangs like an icicle from the ceiling or sides of a cavern. A stalagmite appears like an inverted stalactite, rising from the floor of a cavern.

 Stalactites hanging from the ceilings of caverns commonly exhibit a central tube or the trace of a former tube whose diameter is that of a drop of water hanging by surface tension. A drop on the tip of a growing stalactite leaves a deposit only around its rim. Downward growth of the rim makes the tube. The simplest stalactite form, therefore, is a thin-walled stone straw, and these fragile forms may reach lengths of 0.5 m (20 inches) or more where air currents have not seriously disturbed the growth. The more common form is a downward-tapering cone and is simply a thickening of the straw type by mineral deposition from a film of water descending the exterior of the pendant.

 Stalagmites have thicker proportions and grow up on the bottom of a cavern from the same drip-water source, the mineral from which is deposited after the water droplet falls across the open space in the rock. Not every stalactite has a complementary stalagmite, and many of the latter may have no stalactite above them. Where the paired relation exists, however, continual elongation of one or both may eventually result in a junction and the formation of a column.

 The dominant mineral in such deposits is calcite (calcium carbonate), and the largest displays are formed in caves of limestone and dolomite. Other minerals that may be deposited include other carbonates, opal, chalcedony, limonite, and some sulfides.

      Conditions that favour the deposition are: (1) a source rock above the cavern; (2) downward percolation of water supplied from rain; (3) tight but continuous passageways for this water, which determine a very slow drip; and (4) adequate air space in the void to allow either evaporation or the escape of carbon dioxide from the water, which thus loses some of its solvent ability.

* * *


Universalium. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • stalactite, stalagmite — Only geologists are likely to use these terms often, but others have difficulty in remembering which hangs down from the roof of a cave and which rises up from the floor. Both stalactite and stalagmite refer to deposits of calcium carbonate… …   Dictionary of problem words and expressions

  • stalagmite —    1. Speleothem, normally of calcite, formed by upward growth from a cave floor, and therefore the complement of a stalactite. Stalagmites form when dripwater that is still saturated falls from a cave roof or stalactite and, when or after it… …   Lexicon of Cave and Karst Terminology

  • stalagmite — stalactite, stalagmite A stalactite hangs down from the roof of a cave, and is formed from dripping water containing rich minerals. A stalagmite rises up from the floor and is formed from deposits also caused by dripping. Both words are derived… …   Modern English usage

  • stalactite — stalactite, stalagmite A stalactite hangs down from the roof of a cave, and is formed from dripping water containing rich minerals. A stalagmite rises up from the floor and is formed from deposits also caused by dripping. Both words are derived… …   Modern English usage

  • Stalactite — A stalactite (Greek stalaktites , (Σταλακτίτης), from the word for drip and meaning that which drips ) is a type of speleothem (secondary mineral) that hangs from the ceiling or wall of limestone caves. It is sometimes referred to as dripstone.… …   Wikipedia

  • Stalagmite — A stalagmite (from the Greek stalagma ( ), drop or drip ) 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. . If these formations grow… …   Wikipedia

  • stalagmite —   a similar feature to a stalactite, formed by the same process, but found on the cave floor beneath the stalactite above. Tend to be shorter and more rounded due to the impact of the falling drip …   Geography glossary

  • STALACTITE —    a cone of carbonate of lime attached like an icicle to the roof of a cavern, and formed by the dripping of water charged with the carbonate from the rock above; Stalagmite being the name given to the cone formed on the floor by the dripping… …   The Nuttall Encyclopaedia

  • Phong Nha-Ke Bang National Park — Infobox World Heritage Site WHS = Phong Nha Ke Bang National Park State Party = VIE Type = Natural Criteria = viii ID = 951 Region = Asia Pacific Year = 2003 Session = 27th Link = http://whc.unesco.org/en/list/951Infobox protected area | name =… …   Wikipedia

  • Aggtelek Caves — ▪ caves, Hungary also called  Baradla Domica Caverns        limestone cave system on the Hungarian Slovakian border, about 30 miles (50 km) northwest of Miskolc, Hungary, and 40 miles (65 km) southwest of Košice, Slovakia. It is the largest… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”