Stalagmite
A stalagmite (
The corresponding formation hanging down from the ceiling of a cave is a stalactite. Mnemonics have been developed for which word refers to which type of formation; one is that stalactite has a C for "ceiling", and stalagmite has a G for "ground",[4] another is that, as with ants in the pants, the mites go up and the tights (tites) come down.
Formation and type
Limestone stalagmites
The most common stalagmites are
If stalactites – the ceiling formations – grow long enough to connect with stalagmites on the floor, they form a column.
Stalagmites should normally not be touched, since the rock buildup is formed by minerals precipitating out of the water solution onto the existing surface;
Lava stalagmites
Another type of stalagmite is formed in lava tubes while molten and fluid lava is still active inside. Their mineralogical composition, close to that of siliceous minerals commonly found in basalt (for example, obsidian), the main constituent of volcanic glass, is different. Their mechanism of formation/crystallization is also notably different from that of limestone stalagmites (CaCO
3) but the common point is that it remains driven by gravity. Drops of molten lava (siliceous material, SiO
2) solidify onto the floor of the already emptied lava tube, when the lava temperature sufficiently decreases after the passage and the complete purge of the main lava flow. Essentially, it is still the gravity deposition of material onto the floor of a cave (or a void).
However the difference from calcareous stalagmites is that the transport of siliceous material occurs in the molten state and not dissolved in aqueous solution; CO2 degassing does not play any significant role. With lava stalagmites, their formation also happens very quickly in only a matter of hours, days, or weeks, whereas limestone stalagmites may take up to thousands or hundred thousands of years. A key difference with lava stalagmites is that once the molten lava has ceased flowing, so too will the stalagmites cease to grow. This means that if the lava stalagmites were to be broken, they would never grow back.[2] Stalagmites in lava tubes are rarer than their stalactite counterparts because during their formation, the dripping molten material most often falls onto still-moving lava flow which absorbs or carries the material away.
The generic term "lavacicle" has been applied to lava stalactites and stalagmites indiscriminately, and evolved from the word "icicle".[2]
Ice stalagmites
A common stalagmite found
Ice stalactites may also form corresponding stalagmites below them, and given time, may grow together to form an ice column.
Concrete derived stalagmites
Stalactites and stalagmites can also form on concrete ceilings and floors, although they form much more rapidly there than in the natural cave environment.[10][11]
The secondary deposits derived from concrete are the result of concrete degradation, where
Secondary deposits, which create stalagmites, stalactites, flowstone etc., outside the natural cave environment, are referred to as "calthemites".[11] These concrete derived secondary deposits cannot be referred to as "speleothems" due to the definition of the word.[10]
Records
The largest known stalagmite in the world exceeds 70 metres (230 ft) in height and is in
In the
Photo gallery
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Coves d’Artà, Mallorca, Spain
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Seven-star Cave, Guilin, China
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A “crayfish back”, Jenolan Caves, New South Wales, Australia
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Hérault, France
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Castellana Grotte, Apulia, Italy
References
- ^ σταλαγμίας, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus.
- ^ a b c Larson, Charles (1993). An Illustrated Glossary of Lava Tube Features, Bulletin 87, Western Speleological Survey. p. 56.
- ^ Hicks, Forrest L. (1950). "Formation and mineralogy of stalactites and stalagmites" (PDF). 12: 63–72. Retrieved 2013-07-08.
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: Cite journal requires|journal=
(help) - ^ "Archived copy" (PDF). Archived from the original (PDF) on 2017-02-11. Retrieved 2015-02-08.
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: CS1 maint: archived copy as title (link) - Nova. PBS. Retrieved 2013-07-01.
- ^ C. Michael Hogan. 2010. “Calcium”. eds. A. Jorgensen, C. Cleveland. Encyclopedia of Earth. National Council for Science and the Environment.
- )
- ^ Keiffer, Susan (2010). "Ice stalactite dynamics". Retrieved 2013-07-08.
- ^ Lacelle, Denis (2009). "Formation of seasonal ice bodies and associated cryogenic carbonates in Caverne de l'Ours, Québec, Canada: Kinetic isotope effects and pseudo-biogenic crystal structures" (PDF). Journal of Cave and Karst Studies. pp. 48–62. Retrieved 2013-07-08.
- ^ a b Hill, C A, and Forti, P, (1997). Cave Minerals of the World, 2nd editions. pp. 217 & 225 [Huntsville, Alabama: National Speleological Society Inc.]
- ^ a b c Smith, G K. (2016). "Calcite straw stalactites growing from concrete structures". Cave and Karst Science, 43(1), 4–10.
- ^ Macleod, G, Hall, A J and Fallick, A E, 1990. An applied mineralogical investigation of concrete degradation in a major concrete road bridge. Mineralogical Magazine, Vol.54, 637–644.
- ^ Sundqvist, H. S., Baker, A. and Holmgren, K. (2005). "Luminescence in fast growing stalagmites from Uppsala, Sweden". Geografiska Annaler, 87 A (4): 539–548.
- ^ Smith, G K., (2015). "Calcite Straw Stalactites Growing From Concrete Structures". Proceedings of the 30th 'Australian Speleological Federation' conference, Exmouth, Western Australia, edited by Moulds, T. pp. 93–108.
- ^ "Son Doong Cave (Hang Sơn Đoòng)". Wondermondo. 15 June 2014.