Photo stalactites. Stalactites and stalagmites Fused stalactites and stalagmites

Why do caves appear

The earth's surface has a structure that is complex in composition and configuration. At one time, when the formation of land and oceans took place, various minerals were also formed. For example, basalt appeared at high temperature and pressure as a result of volcanic activity. Granite also arose under the same conditions. But limestone, marble, chalk, gypsum and salt, which can be composed of stalactites and stalagmites, were formed according to a different mechanism, in less extreme circumstances. All of them dissolve in water - this is their distinctive property. When water washes these elements out of the composition of rocks, voids appear inside. They are called caves.

Empty space inside any body is karst. In accordance with this term, most of the caves known to people began to be called karst. I must say that caves can also be formed as a result of other processes occurring in the earth's crust, but this is a topic for a separate discussion. It is important to emphasize that stalactites and stalagmites appear precisely in karst formations. In these voids, natural processes do not stop even for a moment, although they continue for many millions of years. Scientists have calculated that stalactites and stalagmites grow by about 1 cm in 100 years.

According to experts, the largest karst cave on the planet is located in the United States. Kentucky is famous for its Mammoth Caves, whose stalactites and stalagmites attract both tourists and scientists. These caves communicate with each other. The total length of underground halls and passages is 560 kilometers. On the island of Crete there are almost one and a half thousand caves. The most interesting of them is Sfedoni. Its age is estimated from seven to fifteen million years. It has modest dimensions, only 145 meters. However, its interior (so to speak) is remarkable for its amazing proportions and beauty. It looks like it was made by human hands.

At first, acquaintance with the caves, some people have a question about how stalactites and stalagmites differ? Speaking in everyday language, stalactites are "icicles" that hang from the ceiling. Water seeps through soil and rock, eroding along the way those minerals that dissolve in it. Getting into the cave room, water evaporates, and minerals remain in the dry residue. The icicle gradually grows and increases in size. In the case when the mineral solution is formed weakly saturated, its drops fall from a height and reach the floor. In this place, an "icicle" is also formed, only with the tip up. This is a stalagmite.

Experts and lovers of underground routes do not get tired of being surprised by the variety of caves on the planet. It would seem that everything has already been studied and explained. However, new facts make us return to the same questions again and again. It is well known that stalactites and stalagmites are formed as a result of the evaporation of moisture that penetrates from the outside. However, recent studies have shown that this is not always the case. From what has been said, it follows that the caves have not yet revealed all their secrets. Curious and energetic researchers have yet to break their heads over their solution.

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Aquatic chemogenic cave deposits are formed by sedimentation from flowing or stagnant water. They are represented by various forms of sinter formations.
stalactites(from the Greek stalaktós - flowing drop by drop) - drip-drip (usually calcareous in karst caves) formations hanging in the form of conical icicles, draperies, curving fringe or hollow tubes from the vaults and upper parts of the walls of karst caves or other underground voids (English : Speleothem). This is the most widely known manifestation of the gravitational textures of mineral aggregates. The terms "stalactite" and "stalagmite" were introduced into literature in 1655 by the Danish naturalist Ole Worm.
Stalactites result from the precipitation of calcium carbonate during decomposition in a solution of calcium bicarbonate with the formation of less soluble calcium carbonate and CO 2, and the removal of carbon dioxide from water saturated with it. The solubility of carbonates depends on the presence of CO 2 in solution. Once the CO 2 limit in the pore solution is used up, carbonate dissolution will stop. When the solution is close to saturation, some parts of the overall filtration-diffusion system will dissolve, while others will precipitate carbonate. In this case, dissolution can occur on the walls of thin pores and cracks, and precipitation can occur on individual crystallization nuclei in an open cavity.
There are also gypsum and salt stalactites formed by increasing the saturation of the solution during the evaporation of the solvent (water).
Under certain conditions, from the bottom of caves and other underground karst cavities grow towards stalactites stalagmites in the form of cones, and the merging stalactite and stalagmite form columnar columns called stalagnate. On stalactites or stalagmites, partially flooded by groundwater in caves, grow save(aggregates crystallizing in a horizontal plane at the water-air boundary from the edges of the solid phase), as a result of which complex ensembles of mushroom-shaped aggregates are formed.
Gura, or calcite dams that spring up underground lakes - are found mainly in limestone and much less often in dolomite cavities. They are formed in horizontal and inclined passages as a result of precipitation of calcium carbonate from the solution, which is associated with the release of carbon dioxide due to the turbulence of the water flow and / or changes in its temperature when moving through the underground gallery. The outlines of the dams, which usually have the form of a regular or curved arc, are determined mainly by the initial shape of the protrusions of the floor of the cave. According to morphological features, the gurs are divided into areal and linear. The latter are developed mainly in narrow passages with underground streams, which they divide into separate reservoirs. The water flow not only creates calcite dams, but also destroys them. With a change in flow rates and mineralization of groundwater, holes, breaks and cuts are formed in the gures under the influence of erosion and corrosion. This leads to the formation of dry gours, unable to hold water. As a result of further dissolution and erosion, only heavily corroded protrusions remain in place of the calcite dams, which are noted on the floor and walls of the cavity.
"Icicles" of ice, both in ice caves and on the surface of the Earth, are also stalactites. According to V.I. Stepanov, the following types of stalactites are distinguished for karst caves:
with strictly axial feeding, tubular stalactites (macaroni) appear, which are characterized by a constant channel diameter and a structure controlled by geometric selection during the growth of a drop on the meniscus;
with combined areal and axial feeding, conical stalactites appear. They cannot be considered simply as tubular stalactites overgrown with a spherulitic crust, since synchronous fouling affects the morphology of the meniscus;
with linear nutrition, draperies occur;
ensembles of stalactites and draperies are extremely characteristic;
Tuflaktites can be especially distinguished - stalactites growing under conditions of high supersaturation, consisting of calcareous tuff, and thus devoid of the structure specified by geometric selection. The separation of concepts also removes the conflict between the widespread definition that tubular stalactites are always single-crystal and the existence of tubular tuflaktites, which are typical, for example, for adits of the Khaidarkan deposit.
Stalactite-stalagmite crust, as well as the tuff stalactite-stalagmite crust (Stepanov, 1971), essentially consist of aggregates of extremely similar structures and textures with the same characteristic symmetry. At the same time, the specific compositions of these cores can vary considerably in terms of aggregates. There are caves with a sharp predominance of stalagmite forms, and vice versa. In most cases, as shown in [Maksimovich, 1965], the ratio of the number of stalactite and stalagmite forms is controlled solely by the degree of flooding of the cave.
According to V.A.Maltsev, “The existing division of stalactites into types of nutrition (external-internal) does not correspond either to their morphology, or to their structure, or to the real mechanisms of their nutrition. In true stalactites crystallizing as a result of solution degassing or melt cooling, the central channel is not a cause, but a consequence, and the “feeding” through the channel observed in some tubular stalactites is secondary.”
Stalactite-like aggregates of chalcedony, quartz, goethite, and many minerals described as stalactites from the secretions of effusive and sedimentary rocks and from the voids of ore veins, upon careful study, almost always turn out to be pseudostalactites or other stalactite-like forms of aggregates.
Travertine(travertine terraces) is formed by precipitation of calcite and/or aragonite from solutions containing calcium bicarbonate. This process occurs, in particular, with a drop in pressure during the release of groundwater to the earth's surface. As a result, a chemical reaction occurs during which calcium carbonate, which is insoluble in water, is released. In the presence of carbon dioxide in geothermal water, CaCO3 dissolves as calcium bicarbonate:
CaCO3 + CO2 + H2O \u003d Ca (HCO3) 2
With the release of geothermal water to the Earth's surface, the partial pressure of CO2 decreases and the carbonate-calcium equilibrium in it shifts towards the formation of a solid phase: Ca(HCO3)2 = CaCO3↓ + CO2 + H2O.
When the carbonate-calcium balance is disturbed in geothermal water, a suspension of CaCO3 crystals up to 10 microns in size and more is formed. The amount of suspension formed in this case is from 4 to 25 mg/l. The main share is accounted for by particles less than 1 μm in size. Some of them, falling into the laminar sublayer, settle on solid surfaces forming deposits. Depending on the speed of the water flow relative to the settling surface, deposits of various densities are formed on it.

Literature:
Maksimovich G.A. Genetic series of sinter deposits of caves (carbonate speleolithogenesis) // Caves, issue 5(6). Perm, 1965.
Maltsev V.A. Minerals of the Cap-Kutan karst cave system (southeast of Turkmenistan) // "World of Stones", 1993, No. 2 (rus/eng).
Maltsev V.A. Once again about stalactites with "internal" and "external" nutrition // Full version in English: V.A.Maltsev. Staractites with "internal" and "external" feeding, Proc. Univ. Bristol Spel. Soc., 1998, 21(2), 149-158
Stepanov V.I. Periodicity of crystallization processes in karst caves // Proceedings of Min. museum to them. Fersman. Moscow, 1971, issue 20, p. 161-171.
Stepanov V.I. Structures and textures of mineral aggregates formed in the free space of voids
C. Hill, P. Forti. Cave minerals of the world. NSS, 1986, 238 p.

Water is able to pierce long passages in rocks. Such passages are called caves. Caves in most cases are formed in those places where layers of minerals lie, which water can dissolve. Caves are rarely a single void in a mountain, but more often a series of voids.

These voids take the form of halls or grottoes of various sizes. The caves are usually interconnected by narrow or low passages. In the mountain there are whole underground cities with a system of passages and halls located almost on the same level, or with a slope to one of the sides.

In some chambers, underground rivers or streams flow. There are underground depressions where lakes-pools of various sizes with stagnant water at the bottom of individual grottoes have been preserved.

Chambers are either very large or very small. In North America, there is the famous Mammoth Cave. It consists of two hundred galleries, with a total length of at least two hundred and fifty kilometers. The largest one is thirty meters high. The floor of the caves is usually littered with rock fragments, or covered with dust. The bones of people and animals that lived here many thousands of years ago are often found in caves. Then people did not know how to build houses and hid from the cold and predators in caves.

Nowadays, the caves are inhabited by bats, owls, owls and pigeons.

Primitive man, who lived in caves, left in them his bones and the animals he ate, the coals and ashes of his fires, the remains of stone and bone axes and knives. On the walls of many caves, drawings and inscriptions have survived to this day.

At the bottom and roof of almost any cave, you can see hard, petrified forms that were formed from lime and water droplets seeping through cracks in the ceiling. Thus, the icicle slowly but surely grows, turning over time into a rather tangible hulk, and it is called a stalactite.

From the floor, at the same time, another icicle grows, wider and flatter - a stalagmite. If there are many cracks in the ceiling, then many stalactites grow on it over time. If you do not break off the stalactites and stalagmites, they eventually, having connected with each other, form a strong shiny column. These droplets on the vault and on the floor of the cave create very beautiful and spectacular architectural ensembles under artificial lighting.

Even more beautiful are the light effects in the caves - glaciers, since the stalactites and stalagmites in them are made of ice. At low temperatures, they grow not only in winter, but also in summer. On walls and vaults, where water does not drip, water vapor is deposited in the form of hoarfrost, consisting of large beautiful ice crystals. These crystals reflect the fire of candles or torches with millions of sparkles.

STALACTITES AND STALAGMITES.

In caves, stalactites are very often found - "icicles" of various sizes hanging from the ceiling, and stalagmites - "icicles" growing from the floor of the cave.

Word " stalactite"translated from Greek means" dripping drop by drop ". The fact is that even the highest stone mountains on Earth are not a solid monolith - they have microcracks through which water seeps from the surface of the mountain into the caves. But water enters the caves through the thickness is very slow - literally rare drops.These droplets of water are slightly washed out of the rock calcium - this is how stalactites are obtained.

Dripping on the floor of the cave, the water brings with it calcium crystals, which begin to fold into a "hill" - stalagmite. Stalagmites are usually thicker than stalactites, because the water splashes when falling and the crystals crumble.

Both stalactites and stalagmites grow very slowly - hundreds and thousands of years. If the cave is not very high, then the stalagmites and stalactites coalesce over time.

On the polished section of the stalagmite, growth rings are clearly visible.

By the way, there is a very simple method of how to remember what to call a stalactite and what a stalagmite - in the word "stalag m it "is the letter M, as in the word" ze m la". So, a stalagmite is something that grows on the ground!

The longest, free-hanging stalactite is considered to be a huge stone icicle in Gruga do Janelao, Brazil, 12 meters long, and the record holder among stalagmites has a height of 32 meters. It is located in the Krasnogorska cave near Roznava, Slovakia.

We have a huge number of caves in Russia where you can see this miracle of nature. If you have the opportunity to visit the caves with a tour - be sure to go - we guarantee impressions of a lifetime!

Lime drip, lime icicle, sinter formation, helictide, mukarn, ledge down Dictionary of Russian synonyms. stalactite n., number of synonyms: 8 ledge (61) ... Synonym dictionary

STALACTITE, a sintered mineral formation consisting of tiny crystals of CALCIUM CARBONATE, hanging in the form of an icicle or fringe from the ceiling of the CAVES, composed of limestones of the Carboniferous period. Stalactites are formed by water, slowly ... ... Scientific and technical encyclopedic dictionary

STALACTITE, stalactite, husband. (from Greek stalaktos dripping) (miner). A calcareous growth on the ceiling of a cave formed by percolating drops of lime-laden water. Explanatory Dictionary of Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov

STALACTITE, a, husband. An icicle-shaped calcareous growth descending from the ceiling of a cave, formed by seeping drops. | adj. stalactite, oh, oh. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

Miner. sinter formation growing on the ceilings of caves, mines and descending down in the form of icicles. Formed during the evaporation of minerals. water seeping through limestone cracks. Such water is hard, since the content. calcium carbonate ... ... Geological Encyclopedia

stalactite- a, m. stalactite f. gr. stalaktos dripping. A calcareous build-up on the ceiling or upper part of the walls of underground voids (caves, galleries, etc.), formed by seeping drops of water containing calcium bicarbonate. BAS 1. Lime ... ... Historical Dictionary of Gallicisms of the Russian Language

stalactite- Leaky drip formation in the form of icicles or fringes hanging from the ceiling of a karst cave, arising from the constant supply of carbonate in the form of calcite from percolating groundwater ... Geography Dictionary

STALAGMITE or STALACTITE (Greek, from stalagma thickened drops). Lime deposits formed at the bottom of the caves, due to the slow and continuous dripping of lime water from the vaults, have the shape of cones with their tops up. Dictionary of foreign ... ... Dictionary of foreign words of the Russian language

M. Sintered limestone formation in the form of large icicles on the ceiling or upper part of the walls of underground voids (caves, galleries, etc.), formed by seeping drops of water saturated with calcium and carbon dioxide. Explanatory Dictionary of Efremova ... Modern explanatory dictionary of the Russian language Efremova

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