What are stalactites and stalagmites made of? Stalagmites, stalagnates and other sinter formations. Stages of formation of karst caves

Cave stalactites people have always been interested. Among sinter stalactite formations, gravitational (thin-tube, cone-shaped, lamellar, curtain-shaped, etc.) and anomalous (mainly helictites) are distinguished.

Particularly interesting thin tubular stalactites sometimes forming whole calcite thickets.

Their formation is associated with the release of calcium carbonate or halite from infiltration waters. Leaking into the cave and getting into new thermodynamic conditions, the infiltration waters lose some carbon dioxide. This leads to the release of colloidal calcium carbonate from a saturated solution, which is deposited along the perimeter of a drop falling from the ceiling in the form of a thin roller. Gradually growing, the rollers turn into a cylinder, forming thin-tubular, often transparent stalactites. The inner diameter of tubular stalactites is 3–4 mm; the wall thickness usually does not exceed 1–2 mm. In some cases, they reach 2–3 and even 4.5 m in length.

Among the most common stalactites cone-shaped stalactites

Their growth is determined by water flowing down a thin cavity located inside the stalactite, as well as by the influx of calcite material along the surface of the incrustation. Often the internal cavity is located eccentrically. From the opening of these tubes every 2-3 minutes. dripping clear water. The sizes of cone-shaped stalactites, located mainly along cracks and indicating them well, are determined by the conditions of calcium carbonate supply and the size of the underground cavity. Usually stalactites do not exceed 0.1–0.5 m in length and 0.05 m in diameter. Sometimes they can reach 2–3, even 10 m in length () and 0.5 m in diameter.

interesting spherical (bulb-shaped) stalactites formed as a result of blockage of the opening of the tube. Aberration thickenings and patterned outgrowths appear on the surface of the stalactite. Spherical stalactites are often hollow due to the secondary dissolution of calcium by water entering the cave.

Anemoliths - curved stalactites

In some caves, where there is significant air movement, there are curved stalactites - anemoliths, the axis of which is deflected from the vertical.

The formation of anemoliths is determined by the evaporation of hanging water droplets on the leeward side of the stalactite, which causes it to bend in the direction of the air flow. The bending angle of individual stalactites can reach 45°. If the direction of air movement periodically changes, then zigzag anemoliths.

Curtains and draperies hanging from the ceiling of caves have a similar origin with stalactites. They are associated with infiltration water seeping along a long fissure. Some curtains, composed of pure crystalline calcite, are completely transparent. In their lower parts, stalactites with thin tubes are often located, at the ends of which water droplets hang. Calcite deposits can look like petrified waterfalls. One of these waterfalls is noted in the grotto of Tbilisi in the New Athos (Anakopia) cave. It is about 20 meters high and 15 meters wide.

- these are complexly built eccentric stalactites, which are part of a subgroup of anomalous stalactite formations. They are found in various parts karst caves(on the ceiling, walls, curtains, stalactites) and have the most diverse, often fantastic shape: in the form of a curved needle, a complex spiral, a twisted ellipse, a circle, a triangle, etc. Acicular helictites reach 30 mm in length and 2–3 mm in diameter. They are a single crystal, which, as a result of uneven growth, changes its orientation in space.

There are also polycrystals that have grown into one another. In the section of acicular helictites, growing mainly on the walls and ceiling of caves, the central cavity is not traced. They are colorless or transparent, their end is pointed. Spiral helictites develop mainly on stalactites, especially thin tubular ones. They are made up of many crystals. Inside these helictites, a thin capillary is found, through which the solution reaches the outer edge of the aggregate.

Water droplets formed at the ends of helictites, unlike tubular and conical stalactites, long time(many hours) do not come off. This determines the extremely slow growth of helictites. Most of them belong to the type of complex formations that have a bizarrely intricate shape.

The most complex mechanism of the formation of helictites is currently not well understood. Many researchers (N.I. Krieger, B. Zhese, G. Trimmel) associate the formation of helictites with blockage of the growth channel of thin-tubular and other stalactites. Water entering the stalactite penetrates into the cracks between the crystals and comes to the surface.

This is how the growth of helictites begins, due to the predominance of capillary forces and crystallization forces over gravity. Capillarity is, apparently, the main factor in the formation of complex and helical helictites, the direction of growth of which initially largely depends on the direction of intercrystalline cracks.

F. Chera and L. Mucha (1961) by experimental physicochemical studies proved the possibility of precipitation of calcite from the air of caves, which causes the formation of helictites. Air with a relative humidity of 90-95%, supersaturated with tiny droplets of water with calcium bicarbonate, turns out to be an aerosol. Droplets of water that fall on ledges of walls and calcite formations quickly evaporate, and calcium carbonate precipitates.

The highest growth rate of a calcite crystal goes along the main axis, causing the formation of needle-like helictites. Therefore, under conditions where the dispersion medium is a substance in a gaseous state, helictites can grow due to the diffusion of a dissolved substance from the surrounding aerosol. The helictites created in this way ("aerosol effect") are called "cave hoarfrost".

Along with the clogging of the feeding channel of individual thin-tubular stalactites and the “aerosol effect”, the formation of helictites, according to some researchers, is also influenced by the hydrostatic pressure of karst waters (L. Yakuch), air circulation features (A. Vihman) and microorganisms. These provisions, however, are not sufficiently substantiated and, as studies have shown recent years are largely debatable. Thus, the morphological and crystallographic features of eccentric sinter forms can be explained either by capillarity or by the influence of aerosol, as well as by a combination of these two factors.

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 them began to be called karst. known to people caves. 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.

Avshalom cave located on western slopes Judean mountains in Israel, is real natural museum(with an area of ​​​​more than 5000 square meters), in which numerous stalactites and stalagmites. These outgrowths reach about 4 m in length and resemble outlandish objects: huge pieces of fabric, Coral reefs or bunches of grapes... Special lighting installed in the cave further enhances the mystical effect, so that Avshalom is quite like a ready-made scenery for some horror movie.

Recall that stalactites and stalagmites are formed from water that mixes with limestone and flows down from the cave ceiling. For hundreds of thousands of years, drops of mineralized water solidify on the floor and ceiling, gradually forming tall columns and hanging outgrowths.

The Avshalom Cave was discovered by accident in May 1968 during the extraction of building rubble. After another explosion, the workers saw the entrance to the cave. The first impression was fantastic: the cave shimmered with all the colors of the rainbow, as if it was strewn with mountains of diamonds. Later, having descended, the discoverers saw that the sun shone with water that flowed down the stalactites.

Geologists took up the study of the cave and found that it was formed about 25 million years ago, when the mountain range of the Judean Hills rose above the surface of the water. For thousands of years, water saturated with carbon dioxide seeped through cracks and through the soil layer, which formed the “decoration” of the karst cave. Currently, the cave maintains a constant temperature (+22 C) and high humidity (92 -100%) all year round, which ensures the continuous growth of stalactites and stalagmites.

The cave is named after an Israeli soldier, Avshalom Shoham, who died during the war of attrition (1967-1970). After the cave was discovered, the secret of its existence was kept for several more years, because the government was afraid that negligent tourists would simply break the beauty that had been created by nature for thousands of years. Avshalom became accessible to visitors only in 1975, since then tourists from all over the world have been coming to see this natural wonder.

Gulyaeva Milena Nikolaevna, student of the 2nd "B" class of the Moscow Autonomous Educational Institution of the Domodedovo Secondary School No. 2, Class. head Ponomarenko I. Yu.

The goals of the project "Stalactites and stalagmites":

1. Learn what stalactites and stalagmites are.

2. To study the process of the appearance of stalactites and stalagmites.

3. Conduct an experiment on creating stalactites at home.

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Project on the topic "Stalactites and stalagmites".

Prepared by a student of 2 "B" class Gulyaeva Milena Nikolaevna.

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Objective of the project:

1. Learn what stalactites and stalagmites are.

2. To study the process of the appearance of stalactites and stalagmites.

3. Conduct an experiment on creating stalactites at home

conditions.

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Introduction

One fine winter day, I came across a note about the Nikitsky caves, located in the vicinity of my hometown Domodedovo.

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I was wondering what is in them? I decided to ask my sister about it. She said that some kind of stalactites and I did not understand anything. I open the encyclopedia, and there ...

Whole new world, the world of underground nature! And the most beautiful phenomenon of the caves seemed to me those same stalactites. How beautiful and bizarre their shapes and sizes are. Let me tell you now!

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Let's understand how stalactites and stalagmites appear. And stalactites and stalactites grow very slowly - hundreds and thousands of years.

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If the cave is not very high, then the stalactite and stalagmite grow together and a stalagnate is obtained. Stalactite - growing from above Stalagmite - growing from below Stalagnate - fused icicles of stalactite and stalagmite.

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The word stalactite is translated from Greek as "leaked drop by drop".

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Stalactites arise as a result of a process called karst (karst process). Water, saturated with limestone, reaches the ceiling of an already created cave through the smallest cracks and hangs on it. The fact is that even the highest stone mountains they are not a solid monolith; they have microcracks through which water seeps from the surface of the mountain into the caves.

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As I understand it, stalactites can consist of different substances, but the main creator is water, it dissolves mineral salts, limestone and rocks. Stalactites can form from many soluble substances, but the most common are:

1. Calcite (limestone) stalactites.

2. Gypsum stalactites.

3. Salt stalactites.

4. Ice stalactites.

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Among the many stalactites and stalagmites there are unusual ones - they have their own names, for example: "Witch's finger", "Sorek" cave, "Gentle" cave.

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While reading a children's encyclopedia, I saw the experience of growing stalactites and decided to repeat it myself. All stages of this experience were documented.

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Objectives of the experiment: to conduct an experiment on growing a stalactite at home; fix the stages of the experiment; draw conclusions based on the findings.

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First, I make a saturated solution of soda.

Then I pour it into jars connected with a woolen thread.

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Day after day, I watched the growth of "home" stalactites and recorded them

Value. Here's what I got!

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Conclusion

After the experiment, I realized that stalactites grow for a long time, but growing

"Home" stalactites are possible! This is very interesting and educational.

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Summarizing.

During my research on this topic, I:

1. Studied the history of such natural phenomena as stalactites and stalagmites.
2. Learned a lot of new and interesting facts about caves.
3. She conducted a fascinating experiment on growing stalactites in artificially created conditions.
4. Prepared a colorful presentation for those who are interested in the beautiful and wonderful world nature!

Thank you for your attention!!!

Nature has always been and remains a mystery to man, both in distant primitive times and in modern world. One of these mysteries of modern times are caves. Previously, people were not interested in where they came from - the main thing is that they served as a reliable shelter from bad weather and enemies. Today, the study of caves is engaged in a special science - speleology. Speleologists study in detail all the regularities in the appearance of depressions, the composition of rocks, the characteristics of flora and fauna, and also give forecasts for their development. The caves contain a lot of interesting things: unknown living creatures, various water sources, processes - stalactites and stalagmites. We will talk about them in this article.

How are stalactites and stalagmites formed?

Such processes are formed mainly in karst and caves - where a large number of mineral rocks. These include limestone, chalk, dalamit, marble, gypsum, salt. Under the influence of rain moisture, which contains dissolved carbon dioxide, the rocks are eroded, and sedimentary water flows into such caves. The appearance of one or another type of processes depends on the rate of water runoff.

- a process consisting of mineral rock and formed from the ceiling of the cave. It is formed when water flows slowly and drops linger for a long time at the top of the cave recess. In the caves, a lower temperature prevails, and it is precisely this that contributes to the solidification of drops. So gradually flowing and solidifying drops form a certain stone formation in the form of a thick needle, but most of all, the shape of a stalactite resembles an icicle.

Stalagmite- an outgrowth consisting of mineral rock and formed from the lower surface of the cave. It occurs when sedimentary water flows quickly from the ceiling of the cave space and hits one point on the floor. On the lower surface of the cave, the temperature is even lower than at the top, and the drops solidify even faster. Under the force of gravity, the drop hits the floor and spreads a small distance in a circle from the place where the drop fell. Such solidification of drops forms a thick and dense base of the stalagmite, and it looks like a cone-shaped process with a pointed top.

The frequency of location of stalactites and stalagmites depends on the degree of permeability of the cave surface and on the composition of mineral rocks. If the rocks are mostly limestone or gypsum, they will dissolve faster and the water will run down the top of the cave faster. Stalactites and stalagmites in such a rock will be fragile, therefore, when examining such caves, one must be careful - do not touch the processes, neither scream, nor stomp, otherwise injuries from the fall of such formations are inevitable. Sometimes stalactites and stalagmites merge into one continuous column - stalagnate; such columns can form whole columns inside the caves.

Stalactites can look different, it depends on the composition of the rocks and the chemical processes that occur under the influence of carbon dioxide and water. Also big influence the temperature and air circulation in the cave exerts, if the wind often walks inside, then the threads, processes can be indirect, curved, arcuate. So in the cave you can see a fringe of stalactites, scallops, drapery, threads, various figures, fungi. The shape of stalagmites can also be different - from simple conical columns to flattened fungi.

Formations in the form of offshoots in karst caves can grow for centuries. Some grow faster, some take longer. On everything the globe there are thousands of karst caves, many of them have already been studied, many are still unknown to the world.

The world's most famous stalactite and stalagmite caves

"Mammoth Cave" (USA, Kentucky)

According to scientists, it arose about 10 million years ago, got its name due to its size, its length is about 600 km. Inside there is a whole system of mines and branches. Mineral outgrowths in this cave are located on whole floors, in many of its departments and halls, stone blocks stick out directly from the water. The spectacle impresses both speleologists and tourists, but you need to be careful - it is very easy to get lost in it.

"Crystal Cave" (Mexico)

Inside the cave is filled with gypsum crystals, the largest outgrowth reaches 11 meters in height, and its mass is 54 tons! It is unlikely that you will be able to visit such a cave. ordinary tourists because the temperature inside reaches +50 degrees.

"Cave of Throat Barloga" (Russia)

The height of the cave is about 2800 meters, inside there is a whole system of halls, wells and streams of various sizes. The filling in the halls varies from large pyramidal crystalline processes to various clay and calcium deposits. Going down into such a cave is dangerous even for professionals.

Despite all the dangers associated with traveling through such masterpieces of nature, the caves will always beckon with their unique and enchanting beauty, and mysterious silence, where there is its own chronology and its own special course of life.

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