27.09.2019

Cave exploration. Fairy world of caves. Planet Earth

One summer I found myself in a cave for the first time, and in the famous cave of Petralona, located in northern Greece. This cave is of great importance in the field of anthropology and paleontology - it is here, according to Greek scientists, that the skeleton of the oldest Neanderthal man in Europe, who lived in Europe more than 700 thousand years ago, was found. And since then, the question of the cradle of humanity, where humanity nevertheless originated, has been controversial, despite numerous studies and collected evidence.

But most of all, this Greek cave struck me with its size and beauty. Here I first saw a cave lake, stalactites, stalagmites and stalagnates. Passing from hall to hall of this cave, I thought how it happens that “icicles” - stalactites - hang from above. Why do they have such bizarre shapes and do not melt? And below, like trees, other “icicles” grow - stalagmites. What do they grow out of if there are stones around? Why don't they fall? Why are they both hard and brittle at the same time, but wet to the touch? What if you grow a stalagmite or stalactite at home and decorate your room? Or such a curiosity can be useful in everyday life?

After returning home, I decided to investigate this issue. And I had to start with studying the “habitat” of these amazing cave formations - from the caves themselves. There was also a lot of interesting and exciting here. I still had the initial idea and information after visiting the Greek cave. Our guide was very interesting and told in detail about the cave in which I was. But how are the caves themselves born? And why exactly in them, and nowhere else, do stalactites and stalagmites appear? What are these stalactites made of?

In the course of my research, in order to solve the tasks, I had to study science articles and the results of speleological research. Speleology is a science that deals with the study of caves. In addition, I decided to conduct an experiment on growing a stalactite at home.

And in order to understand the nature of stalactites and stalagmites, first I needed to learn everything about caves - what are they and how do they form? I found the necessary theoretical information in encyclopedias and on Internet sites.

Caves. Their education.

A cave is a natural cavity in the upper thickness of the earth's crust, which communicates with the earth's surface by one or more outlets passable for a person. The largest caves are complex systems passages and halls, the total length of which often reaches several tens of kilometers. Caves are an object of speleology study.

Caves have long been associated with the history of human development. Even in the Stone Age, caves saved people from winter cold. But even after the ancient people stopped using the caves as dwellings, the caves were surrounded by an aura of the unusual and strange. The Greeks believed that the caves were the temples of their gods - Zeus, Pan, Dionysius and Pluto. In ancient Rome, it was believed that nymphs and sorceresses lived in caves. The ancient Persians and other peoples believed that the king of all earthly spirits, Mithras, lives in the caves. Today, the vast and beautiful caves attract tourists.

In nature, there are no two identical caves. Caves form in different ways. However, all the largest caves in the world are formed in a similar way. Some large caves began to be created 60 million years ago. Rains poured, rivers overflowed, and monolithic mountains slowly collapsed, and large voids appeared inside the hills, mountains and rocks (Appendix 1).

The rock in which the caves arise is limestone. This is a soft rock, it can be dissolved by weak acid. The acid that breaks down limestone comes from rainwater. Falling raindrops take carbon dioxide from the air and soil. This carbon dioxide turns water into carbon dioxide.

Therefore, acid rain watered limestone for millions of years. They constantly dripped onto the mountains, and cracks began to appear on them. And the rains continued to pour. The water flowed, widening the cracks. She found new cracks in the monolith. The cracks widened into tunnels. Tunnels crossed, niches appeared. After millions of years, the caves took their shape. And the water made the caves bigger and bigger.

Some caves have holes in the ceiling (Appendix 2). They formed in the place where water once accumulated, which then broke into the cave. In the caves you can find rows of galleries going one above the other. Streams of water flow through some caves, in others - after their formation, the water goes down, and the cave dries up.

Caves are hidden everywhere: in the mountains, just in stony soil, composed of soft rocks. Caves are built not only by water, but also by wind, sea surf, and volcanic lava. Caves remain after the extraction of rock salt. There are also ice caves, only they are short-lived.

Types of caves.

The caves can be divided according to their origin into five groups. These are tectonic, marine, glacial, volcanic and, finally, the largest and most common group, karst caves.

Tectonic caves can occur in any rocks as a result of the formation of tectonic faults. As a rule, such caves are found in the sides of river valleys deeply cut into the plateau, when huge rock masses break off from the sides, forming cracks (sherlops), which in turn usually converge with depth like a wedge. Sometimes they form rather deep vertical caves up to 100 m deep. This type of caves is widespread in Eastern Siberia.

Sea caves arose under the influence of splashing waves on stone cliffs along the coast (Appendix 3). Sea waves containing grains of solid material (pebbles, fine sand) dissolved the cliffs. They were destroyed, undermined from year to year by the surf. Separate caves are located under water. They are usually the result of the activity of groundwater, washing out soft rocks, for example, the same limestone.

Glacial caves are found in many glaciers and are formed inside the glaciers by melt water (Appendix 4). Glacial melt water is absorbed by the glacier along large fissures or at the intersection of fissures. At the same time, passages are formed along which a person can sometimes pass. Such caves have the shape of a well and reach a depth of 100 meters or more. In 1993, a giant glacial well "Izotrog" with a depth of 173 meters was discovered and explored.

A special type of glacial caves are caves formed in a glacier at the exit of underground thermal waters. Since the water is hot, it is able to make voluminous galleries. Such caves are located not in the glacier itself, but under it, since the ice melts from below. Thermal glacial caves are found in Iceland, Greenland and reach considerable sizes.

Volcanic or lava caves occur during volcanic eruptions (Appendix 5). The lava flow, cooling down, is covered with a solid crust, forming a lava tube, inside of which molten rock is still flowing. After the eruption has already, in fact, ended, the lava flows out of the tube from the lower end, and a cavity remains inside the tube. It is clear that lava caves lie on the very surface, and often the roof collapses.

However, lava caves can reach very large sizes. Such, for example, as the Kazumura Cave in Hawaii - 65.6 km long and 1100 m deep. And the largest volcanic cave in the world Cueva de Loe Verdes is located on one of the Canary Islands.

Karst caves are the majority of such caves (Appendix 6). It is karst caves that have the greatest length and depth.

Caves are formed due to the dissolution of rocks by water. Therefore, karst caves are found only where soluble rocks occur: limestone, marble, chalk, gypsum and salt. Limestone, and even more so marble, dissolves very poorly with pure distilled water. Solubility increases several times if dissolved carbon dioxide is present in water, and in nature it is always dissolved in water. However, all the same, limestone dissolves poorly, compared, say, with gypsum or, moreover, salt. But it turns out that this has a positive effect on the formation of extended caves, since gypsum and salt caves not only quickly form, but also quickly collapse.

Caves are a special world that has no analogues on the surface. There is neither winter nor summer in the caves. The temperature is always the same. In cold caves, it ranges from +2 to +8 degrees, and in warm and hot - from +15 to +28.

It turns out that the air in the caves is sterile. It has a thousand times fewer germs than on the surface. It turns out that radioactive isotopes of carbon penetrate into the caves along with underground waters. They cause the glow of stalactites, ionize the air, kill microbes.

The longest cave in the world - Flint Mammoth - is located in the USA, in the state of Kentucky. The length of all its corridors is more than 550 kilometers. And the deepest cave is located in Abkhazia - the cave of Krubera-Voronya. A person can go down to 2 kilometers into it.

Despite the fact that so much is already known about caves, more discoveries lie ahead of scientists. Each cave has passages, crevices and corridors that cave travelers - speleologists - do not yet know about. They think that they have already studied everything, but suddenly one day they notice a gap behind a stone blockage, and behind it is a corridor, beyond which there are several more meters of cave beauty.

As a result of these studies, it can be concluded that there are several types of caves, but the most common are karst. For the formation of a cave, a sufficient amount of water precipitation and a successful form of relief are necessary, that is, precipitation from a large area must fall into the cave, and the entrance to the cave must be located noticeably higher than the place where they are unloaded The groundwater.

Stalactites, stalagmites and stalagnates

Water is a great power. She grinds stone when she makes her way, she builds galleries, and then she leaves them, undermines rocks, and they sink, collapse, move. This is how the caves themselves are born. However, water is not only a builder, but also an artist, a sculptor!

Caves are found in different rocks, and water brings different particles into them, builds from different materials: from calcite, gypsum, rock salt. The dissolution and destruction of sedimentary rocks by water is called karst - the karst process.

The karst process is two-faced: water dissolves rock in one place, transfers it to another, and there it creates beautiful sinter formations from the same rock - stalactites and stalagmites.

Stalactites (from the Greek stalaktós - flowing drop by drop), are drip-drop 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 (Appendix 7).

Stalagmites (from the Greek. stálagma - a drop), drip-and-drop formations of columnar, conical and other shapes, rising from the bottom of caves and other underground karst cavities (Appendix 8).

Stalagnates are sag-drop formations in the form of columns that appear in caves when stalactites and stalagmites join (Appendix 9).

How are they formed? Rain drop, seeping through a crack in the rock, dissolves a piece of stone. Thus, each such drop contains particles of limestone or other minerals. By dissolving limestone, water takes away the mineral calcite from it. A drop of solution saturated with calcite through the smallest cracks reaches the ceiling of an already created cave and hangs on it (Appendix 10).

Gradually, very slowly, the drop evaporates, and the piece of calcite or other mineral brought by it with the thinnest film settles on the ceiling. After some time, the next droplet comes to this place and again deposits calcite. Growing, grains of calcite first turn into a thin transparent and empty tube inside. Why empty? Yes, because the drop itself is empty inside.

But then a grain of sand gets into the drop and clogs the tube. Then other drops begin to flow around this tube from all sides, and a stone icicle grows, the same as the ice one - a stalactite.

But the drops come unevenly from one side or the other, and the stalactite is not quite round. And then it rains on the surface, the water becomes dirty, the stalactite darkens. The rain has stopped, the water is clear again, and the next layer of stalactite has become a different color. If you cut it, then the cut will have the same rings as a tree, but not annual ones. Just spring and fall more water, and the stalactite grows faster. The water is darker, and the ring is darker, there is less water, and growth has stopped (Appendix 11).

I even found chemical formula stalactite formation process. Here it is: CaCO3 + H2O + CO2 Ca2+ + 2 HCO3

But not all calcite settles on the ceiling and gives growth to the stalactite. Under their own weight, some of the drops fall to the floor, and a stalagmite grows from below towards the stalactite. When a stalactite and a stalagmite join and grow together, a calcite column is formed - a stalagnate. And stalactites, and stalagmites, and columns are very large - tens of meters in height and several meters in diameter.

Water drops, falling on them, form streams that flow around the columns from all sides, and then there are streaks in the form of ribs. If the drops flow down the wall of the cave, then no less amazing streaks appear on it in the form of stone waterfalls, flags and other fantastic formations.

Sometimes streaks of completely unexpected forms appear in the caves. Stalactites suddenly begin to grow at random, creating bizarre stone weaves. Surprisingly beautiful stone and gypsum stalactite flowers appear on the floor and on the walls - corallites, crystallictites and helictites (Appendix 12).

Where there is an imbalance in the flow of the solution - for example, it drips from above, but so little that the drops immediately spread like a film - hybrid forms arise, the stalagmite blooms with a bush. In this case, a wide variety of transitional forms, polymineral forms, and much more arise. For example, you can find formations that exactly copy the architecture of wasp nests. And the gypsum web, which is thinner than a human hair, crumbles into dust at the slightest fluctuation of air.

Billions of drops over millions of years have created in the cave a whole forest of stalactites, stalagmites, fantastic interior decoration of columns and openwork stone curtains, flags and waterfalls (Appendix 13).

On the floor of the cave, flowing water also deposits calcite and forms "baths" that vary in shape and color. The smallest particles of salts of various minerals and metals - copper, cobalt, iron - make the stains pink, yellow, blue, red, carrot, black. Very rarely found in the "baths" the so-called cave pearls. It is formed in the same way as the sea, but not in the shell. Sometimes cave pearls reach three to five centimeters in diameter - almost like a ping-pong ball - but this is very rare.

A wide variety of stalactites can be found in karst caves. For example, tubular stalactites, they are pasta. The channel, which runs along their entire length, for centuries automatically suggested to researchers that the stalactite is fed through this channel. But it turned out that this was not the case at all. It turned out that the channel is just a consequence of crystallization along the perimeter of the detached drop. That is why new stalactites, growing in place of the broken ones, do not continue the original pipe, but grow slightly to the side, where it is more convenient for water to drip.

The most spectacular of the stalactites are draperies (Appendix 14) that appear on sloping walls. It is then that the growing stalactite begins to influence the point of separation of the drop, and it becomes mobile, moving along the slightest whim of the water stream and fixing in its dashingly swirling form the direction of these jets, where they should flow.

When a mineral changes, say, calcite to gypsum, the cave also changes, and beyond recognition (Appendix 15). Gypsum has a different crystallization chemistry. Therefore, in such a cave, gypsum formations “grow” - “crystal chandeliers” (Appendix 16) and gypsum “snow-covered firs”.

They form in an extremely remarkable way. The cave also has dry and wet seasons, and gypsum is a highly soluble mineral. When moisture settles on the surface, the gypsum dissolves. When the moisture evaporates, the gypsum crystallizes. Water "likes" to settle in depressions, and to evaporate from ledges is elementary physics. And then it turns out that the inner cavity of the stalagmite continues to dissolve, and the outer surface - to grow, moreover, branched bushes of crystals. Those same “snow-covered firs” appear. When the wall becomes thinner so that the stalagmite no longer holds its own weight, then “dying”, it falls into itself, providing its own “reserves” of gypsum for the growth of other formations.

It takes a lot of time to create all this extraordinary underground beauty. Scientists have calculated that, on average, a stalactite grows by four tenths of a millimeter per year and grows by only four centimeters in a hundred years. And in 100 years, a stone icicle will appear at this place - a stalactite 4 centimeters long. And every 100 years, the stalactite will grow by the same amount. And below, where the drop fell, a stone tower will grow - a stalagmite. After millions of years, the stalactite and stalagmite will unite and turn into a sparkling column. This means that a man who broke a meter-long stone icicle destroyed what nature had been creating for about two and a half thousand years!

Thus, in the course of the study, I learned that stalactites, stalagmites and stalagnates are drip-leak formations in caves. The process of formation of stalactites and stalagmites is a complex chemical process, which consists in the fact that water dissolves the rock, transfers it to another place and after a while deposits it back, creating sinter formations. This process takes hundreds, thousands of years.

Other mysteries of the caves

Paleontology is the science that studies fossil plants and animals. Fossils are the remains of animals that lived millions of years ago, which have survived to this day. It is mainly through the study of fossils that we know what the animal world was like hundreds of millions of years ago.

At the beginning of my work, I already said that the study of caves is of great scientific importance in paleontology, mineralogy, anthropology, and archeology. This is confirmed by the loudest and interesting discovery The 20th century is the discovery of the Petralona cave in northern Greece. I myself was in this cave, and it became the starting point for me in studying the mechanism of formation of caves and stalactites. Therefore, I want to briefly talk about it (Appendices 17-24).

In 1959, on the peninsula of Halkidiki, in northern Greece, at an altitude of 250 meters above sea level, at the foot of Mount Katsika, an entrance to a cave was discovered. It all happened quite by accident, a shepherd named Petralona was tending sheep in the area. Once, having heard the quiet murmur of water, I decided to carefully examine the foot of the mountain and stumbled upon the entrance to the cave. Further research was undertaken by specialists, in particular the famous Greek anthropologist Aris Poulianos, who later built a paleontological museum next to the cave and even sometimes conducts excursions himself. I was lucky, I also saw him when I was on a tour.

The area of the cave is 10 thousand square meters, the total length of the corridors (passages) is 1,500 meters. A tourist route, open to the public, is still only 600 meters. The finds that were discovered inside this cave made a real revolution in anthropology. In 1960, a year after the discovery of the cave itself, a skull and skeleton of an ancient European, a Neanderthal man, called archanthropus, was discovered inside. The results of the first study of the skull were presented at the International Congress of Anthropologists in Moscow in 1964 and produced great impression for specialists.

In addition, petrified bones, stone tools, animal remains - bears, hyenas, turtles, rhinos, lions and even a giraffe were found in the cave. And another unusual find from the Petralona cave is traces of fires and ash, which is 1 million years old. According to scientists, these are the oldest traces of the use of fire by man.

Until recently, it was believed that the age of mankind is 3.5-4 million years, and Africa is the homeland. However, the finds from the Petralone cave and their dating give the right to assume that the cradle of mankind is South-Eastern Europe, and man appeared 11-12 million years ago in Greece. All finds from the Petralona cave are exhibited in the anthropological museum built next to the cave.

In fact, there are a lot of mysteries and mysteries in the caves. As I found out in the course of my research, the animal world of the dungeons is unusual and interesting. Even primitive man knew and painted on the walls of animals that lived in caves - cave lion, hyena, cave bear. By the way, rock paintings also carry a lot of interesting information for scientists (Appendix 25).

Ancient animals died out long ago, people left the caves, but the caves themselves were not empty. serious biological research underworld began only in 1831, when the first cave beetle was found. Since then, many different cave creatures have been discovered - both aquatic and terrestrial. These are troglobionts, which means "living in caves" - crustaceans, fish, wood lice, centipedes, spiders, false scorpions and other insects.

The adaptation of living organisms to cave life is very complex and diverse. Compared with their terrestrial relatives, they have longer and subtle bodies, more elongated legs and antennae, they are transparent and colorless. Since there is no light in the caves, they do not need sight, and therefore they do not have eyes. In the caves there are blind beetles, fish, amphibians, crayfish and even blind and wingless flies. The air in the caves is saturated with moisture, and therefore troglobionts can live both in water and on land.

According to scientists, animals and insects went into the caves due to climate change on Earth, namely during a cold snap. Thus, the majority of modern cave dwellers are representatives of past eras, living fossils that are no longer found on the surface, but have retained the appearance and habits of bygone millennia.

However, most lovers of the dark spend only part of their lives underground. For example, butterflies only hibernate in caves. And the presenters night image life, some species of grasshoppers are there all day. The cave bear also belonged to them, because the cave was for him only a place of rest. The hyena and the lion spent even less time in the caves. Unlike the cave bear, they never went far into the depths of the cave, but stayed at the entrance.

Treasures of the caves - another mystery and mystery of the caves. For many millennia, legends and tales have been talking about treasures hidden in caves. Under the ground, more than once, the bones of lost treasure hunters were found, who never managed to find the treasured treasures. One of the caves in the Czech Tatras is called the Cave of the Treasure Seekers. And how many legends about pirate treasure hidden, including in caves. But in every legend there is some truth.

CONCLUSION

The object of my research was the caves and their mysteries, the main of which are stalactites, stalagmites and stalagnates, the mechanism of their formation and the possibility of creating in domestic conditions, that is, at home. At the beginning of the work, I intended to conduct an experiment on such cultivation. I thought that by studying the nature and mechanism of stalactite formation, I could do the same myself. But even in the course of theoretical research, I realized that it is impossible to grow a real stalactite at home.

In order to grow a stalactite, several very essential conditions are required. Namely - a cave with a certain relief and microclimate, a constant flow of water, the presence of carbon dioxide, and most importantly - several hundred and even thousands of years. human life not enough to repeat such an unusual and beautiful phenomenon as a stalactite or stalagmite. There is only one thing left - to admire and cherish.

Based on the results of my research, I can draw the main conclusion - there are such natural phenomena which a person should study, cherish, but it is not at all necessary to repeat them or use them in their life. Perhaps someday people will invent a time machine or a time accelerator and then they will be able to artificially accelerate the natural process of stalactite growth, but the next question arises, is it necessary?

Why do I need this knowledge? Can they be useful to me in life? I think yes. And mainly, in order to better understand the world around us, to see and appreciate the beauty that nature can create. And yet - suddenly the climate on the Planet will change dramatically again and people will again have to return to the caves. With this knowledge, it will be easier for me to get used to it myself and help others.

“A cave is a cavity in the upper part of the earth’s crust that communicates with the surface by one or more inlets,” Wikipedia gives this definition. In fact, everything is true, but these words do not even remotely convey all the bewitching beauty, all the uniqueness of these natural objects, which gave shelter to the first people hundreds of thousands of years ago, and now amaze their descendants with their power, diversity and, let's not be afraid of this word, splendor.

Brief information about the caves:

Let's start with the fact that they can be simply gigantic in size. For example, the total length of the Mammoth Cave (Kentucky, USA) is more than 678 kilometers, it is considered the longest in the world.

The deepest is located in Abkhazia - Krubera-Voronya (- 2196). But the largest cave in terms of volume is located in Vietnam - Hang Son Dung. The dimensions of its main hall are amazing - 5000 meters long, 150 wide and 200 high. This volume is enough to accommodate 40 skyscrapers! By the way, it was opened only in 2009.

So on our seemingly well-trodden planet, there are still places for amazing geographical discoveries.

Types of caves:

Karst caves- the most numerous and, perhaps, the most beautiful group. It is the caves of this group that amaze us with their depth, length and volume. Formed by dissolving in water various breeds- limestone, gypsum, chalk, salt and even marble. And in tropical climate even quartzite can dissolve in water. An example of this is the relatively recently discovered caves of Abismo Gai Collet (length - 671 m) and Cueva Ojos de Cristal (length 16 km).
In karst caves, due to the physical and chemical processes taking place there, stalactites, stalagmites, helictites are formed, as well as such an amazing sinter formation as cave onyx, which can be up to a meter thick.
Tectonic caves- formed due to tectonic faults in earth's crust. Most often found on the sides of river valleys cut into the plateau.
erosion caves- according to the mechanism of formation, they are somewhat similar to the formation of karst caves. Only if the latter appear due to the dissolution of rocks, then these are due to the erosion of rocks under the influence of water containing solid particles. As a rule, such caves are small, but occasionally quite large ones are found. For example, Bat Cave (length 1.7 km) in Colorado (USA).
Glacial caves formed under the influence of melt water in glaciers. They are usually up to several hundred meters long. special kind ice caves - thermal caves formed under the influence of underground thermal waters. Found in Greenland and Iceland.
Volcanic caves- Formed during volcanic eruptions. The youngest of all types of caves. The mechanism of their formation is as follows. During the eruption, the lava flow, gradually cooling down, is covered with a hard crust from above. A lava tube is formed, inside of which the still liquid lava moves. In the end, the part of the lava that did not have time to solidify flows out of the lower end of such a tube, and a cavity forms inside. Volcanic vents should also be considered caves of this type.

Curious facts about caves

These interesting and in many ways mysterious objects always worried about people. We can say that humanity came out of the caves. Over the millennia, a huge number of facts of "cooperation" of people with them have been accumulated. Let's take a look at the most amazing of them.

Rock paintings found in Spanish cave of Altamira ancient man, created in the era of the Upper Paleolithic (10 thousand years ago). Drawn horses, bison, wild boars are made in several colors. Moreover, the ancient artist was able, using the unevenness of the wall, to achieve a three-dimensional effect for his images!
In the small Australian town of Coober Pedy, located in a very hot area, almost the entire population (about 2 thousand people) lives in caves. City facilities are also located there, incl. cemetery.
In the Luray Cave (Virginia, USA), an organ has been installed that includes stalactites in its design. It turns out an unusual, interesting sound.

Over time, we will post on the site all the interesting facts we have collected and put them in a separate section!

Five of the most interesting caves in the world, open for inspection

Waitomo Caves ( New Zealand, North Island).
Jaita caves (Lebanon).
Cuevas del Drak (Spain, Mallorca).
Kungur ice cave (Russia, Perm region).
Mulu caves (Malaysia, Borneo).

The caves are one of the most interesting objects Land for study and inspection. Ancient people reverently attributed the creation of caves to giants and inhabited them with immortal monsters guarding Realm of the Dead. Now we ourselves have become giants, but we have not ceased to admire these amazing creatures nature.

Every year, thousands of speleologists and speleotourists penetrate this mysterious and exciting underground universe to hear the ringing silence, see the world, plunged into darkness for thousands of years, recognize it and ... freeze with delight.

Before answering the question “How do caves form?”, you need to understand what caves are and what they are.

Caves are empty spaces in rocks underground or under water, as well as above ground. Caves are through with several holes or with one. They are divided into horizontal, vertical, as well as inclined and single-level or multi-level. The size of the cave also varies. It happens that the cave stretches for many kilometers, rises or falls even under the water of an underground river. But the most important difference between one cave and another is the material from which they are composed, and how they were formed.

So, the largest group of caves is Karst. They are divided into marble, salt, crystal, gypsum and limestone caves, as well as others. Such caves are formed due to the dissolution of various rocks in water, and many of them have their own stalactites and stalagmites.

Evolutionists argue that the main factor that forms these caves is carbon dioxide-laden groundwater seeping through cracks along the limestone beds. This process, in their opinion, takes millions of years. But recently another factor has become known that washes out the caves much faster - this is sulfuric acid.

There are also erosive caves by water (along coastline), which are mechanically washed out by water with large grains of sand, fragments of stones, etc. Tectonic caves are formed in the sides of rivers in places of tectonic faults.

Volcanic caves appear during volcanic eruptions, when lava solidifies, creating a kind of pipe through which it flows further, forming voids. Caves in the vents of volcanoes are also volcanic. During the global flood, called Noah's Flood in the Bible, there was worldwide volcanic activity, as a result of which many caves of this type formed very quickly.

Cave - a cavity in the upper part of the earth's crust, communicating with the surface by one or more inlets. Another definition: a cave is a natural underground cavity accessible to human penetration, having parts not illuminated by sunlight and a length (depth) greater than the other two dimensions. The largest caves are complex systems of passages and halls, often with a total length of up to several tens of kilometers. Caves are an object of speleology study. Speleotourists make a significant contribution to the study of caves.

Caves according to their origin can be divided into five groups: tectonic, erosional, ice, volcanic and, finally, the largest group - karst. Caves in the entrance part, with suitable morphology (horizontal spacious entrance) and location (close to water), were used by ancient people as comfortable dwellings.

Caves by origin

Karst caves

Most of these caves. It is karst caves that have the greatest length and depth. Karst caves are formed as a result of the dissolution of rocks by water, so they are found only where soluble rocks occur: limestone, marble, dolomite, chalk, as well as gypsum and salt. Limestone, and even more so marble, dissolves very poorly with pure distilled water. Solubility increases several times if dissolved carbon dioxide is present in water (and it is always present in natural water), but limestone still dissolves poorly compared to, say, gypsum or, moreover, salt. But it turns out that this has a positive effect on the formation of extended caves, since gypsum and salt caves not only quickly form, but also quickly collapse.

A huge role in the formation of caves is played by tectonic cracks and faults. According to the maps of the explored caves, one can very often see that the passages are confined to tectonic disturbances that can be traced on the surface. Also, for the formation of a cave, a sufficient amount of water precipitation is necessary, a successful form of relief: precipitation from a large area should fall into the cave, the entrance to the cave should be located noticeably higher than the place where groundwater is discharged, etc.

Many karst caves are relic systems: the water flow that formed the cave left it due to a change in the relief either to deeper levels (due to a decrease in the local basis of erosion - the bottom of neighboring river valleys), or stopped entering the cave due to a change in the surface catchment, after which the cave goes through various phases of aging. Very often, the studied caves are small fragments of an ancient cave system, opened up by the destruction of the enclosing mountain ranges.

The evolution of karst processes and their chemistry are such that often water, having dissolved mineral substances of rocks (carbonates, sulfates), after some time deposits them on the vaults and walls of caves in the form of massive crusts up to a meter or more thick (cave marble onyx) or special for each cave of ensembles of mineral aggregates of caves, forming stalactites, stalagmites, helictites, draperies and other specific karst mineral forms - sinter formations.

IN Lately more and more caves are being opened in rocks traditionally considered non-karst. For example, in the sandstones and quartzites of the mesas of the tepui mountains of South America, the caves of Abismo Guy Collet with a depth of −671 m (2006), Cueva Ojos de Cristal with a length of 16 km (2009) were discovered. Apparently, these caves are also of karst origin. In a hot tropical climate, under certain conditions, quartzite can be dissolved in water.

Another exotic example of the formation of karst caves is the very long and deepest cave in the US mainland, Lechugia Cave (and other caves in Carlsbad national park). According to the modern hypothesis, it was formed by the dissolution of limestones by rising thermal waters saturated with sulfuric acid.

Tectonic caves

Such caves can arise in any rocks as a result of the formation of tectonic faults. As a rule, such caves are found in the sides of river valleys deeply cut into the plateau, when huge rock masses break off from the sides, forming sagging cracks (sherlops). Seizure cracks usually converge with depth in a wedge. Most often they are covered with loose deposits from the surface of the massif, but sometimes they form rather deep vertical caves up to 100 m deep. Sherlops are widespread in Eastern Siberia. They are relatively poorly studied and probably occur quite often.

erosion caves

Caves formed in insoluble rocks due to mechanical erosion, that is, worked out by water containing grains of solid material. Often such caves are formed on the seashore under the action of the surf, but they are small. However, the formation of caves, worked out along the primary tectonic cracks by streams going underground, is also possible. Quite large (hundreds of meters long) erosional caves are known, formed in sandstones and even granites. Examples of large erosion caves would be T.S.O.D. (Touchy Sword of Damocles) Cave in gabbro (4 km/−51 m, New York), Bat Cave in gneisses (1.7 km, North Carolina), Upper Millerton Lake Cave in granites (California).

Glacial caves

Caves formed in the body of glaciers by melt water. Such caves are found on many glaciers. Melted glacial waters are absorbed by the body of the glacier along large cracks or at the intersection of cracks, forming passages that are sometimes passable for humans. The length of such caves can be several hundred meters, the depth - up to 100 m or more. In 1993, a giant Izortog glacial well, 173 m deep, was discovered and explored in Greenland; the inflow of water into it in summer was 30 m³ or more.

Another type of glacial caves are caves formed in a glacier at the point where intraglacial and subglacial waters exit at the edge of glaciers. melt water in such caves, they can flow both along the glacier bed and on glacial ice.

A special type of glacial caves are caves formed in glaciers at the exit point of underground thermal waters located under the glacier. Hot water is capable of making voluminous galleries, however, such caves do not lie in the glacier itself, but under it, since the ice melts from below. Thermal glacial caves are found in Iceland, Greenland and reach considerable sizes.

Volcanic caves

These caves are formed during volcanic eruptions. The lava flow, cooling down, is covered with a solid crust, forming a lava tube, inside of which molten rock is still flowing. After the eruption has already, in fact, ended, the lava flows out of the tube from the lower end, and a cavity remains inside the tube. It is clear that lava caves lie on the very surface, and often the roof collapses. However, as it turned out, lava caves can reach very large sizes, up to 65.6 km long and 1100 m deep (Kazumura cave, Hawaiian Islands).

In addition to lava tubes, there are vertical volcanic caves - the vents of volcanoes.

Caves by type of host rocks

The longest Mammoth Cave in the world (USA) is karst, laid in limestone. It has a total length of passages of more than 600 km. The longest cave in Russia - the Botovskaya cave, over 60 km long, is laid in a relatively thin layer of limestone, sandwiched between sandstones, is located in Irkutsk region, river basin Lena. Slightly inferior to it is Bolshaya Oreshnaya - the world's longest karst cave in conglomerates in the Krasnoyarsk Territory. The longest cave in gypsum is Optimistic, in Ukraine, with a length of more than 230 km. The formation of such extended caves in gypsum is associated with a special arrangement of rocks: the layers of gypsum that enclose the cave are covered from above with limestone, due to which the vaults do not collapse. Caves are known in rock salt, in glaciers, in solidified lava, etc.

Caves by size

The deepest caves of the planet are also karst: Krubera-Voronya (up to −2196 m), Snezhnaya (−1753 m) in Abkhazia. In Russia, the deepest cave is Throat Barloga (−900 m) in Karachay-Cherkessia. All these records are constantly changing, only one thing is invariable: karst caves are in the lead.

The deepest caves in the world

The depth of a cave is the height difference between the entrance (the highest of the entrances, if there are several) and the lowest point of the cave. If there are passages in the cave located above the entrance, the concept of amplitude is used - the difference in levels between the lowest and highest points of the cave. According to estimates, maximum depth the occurrence of cave passages under the surface (not to be confused with the depth of the cave!) can be no more than 3000 meters: deeper than any cave will be crushed by the weight of the overlying rocks. For karst caves, the maximum depth of occurrence is determined by the karst base (the lower limit of karst processes coinciding with the base of the limestone sequence), which can be lower than the erosion base due to the presence of siphon channels. The deepest cave, at present, is the Krubera-Voronya cave with a depth of 2196 m, this is the first and only cave that crossed the line of 2 km. The first explored cave with a depth of more than 1000 meters was the French Berger abyss, considered the deepest in the world from the discovery in 1953 until 1963.

		Depth, m	Location
1	Krubera-Crow
2
3
4	Lamprechtsofen
5	Mirolda
6	Jean Bernard
7	Torca del Cerro
8	Pantyukhinskaya
9	Sima de la Cornisa
10			Slovenia

The longest caves in the world

		Depth, m	Location
1	Mamontova
2
3	Aux Bel Ha
4	optimistic
5
6
7	Sak-Aktun
8			Switzerland
9	Fisher Ridge
10	Gua Air Jernih		Malaysia

Contents of the caves

Speleofauna

Although the living world of caves, as a rule, is not very rich (excluding the entrance part, where sunlight), however, some animals live in caves or even only in caves. First of all, this the bats, many of their species use caves as a daily shelter or for wintering. Moreover, bats sometimes fly into very remote and hard-to-reach corners, perfectly orienting themselves in narrow labyrinth passages.

Apart from bats, in some caves in areas with warm climate there are several species of insects, spiders (Neoleptoneta myopica), shrimp (Palaemonias alabamae) and other crustaceans, salamanders and fish (Amblyopsidae). Cave species adapt to complete darkness, and many of them lose their organs of vision and pigmentation. Often these species are very rare, many of them are endemic.

archaeological finds

Primitive people used caves all over the world as a dwelling. Even more often, animals settled in the caves. Many animals died in the cave-traps, starting from steep wells. Extremely slow evolution of caves, their constant climate, protection from outside world preserved to us a huge number of archaeological finds. These are pollen of fossil plants, bones of long-extinct animals (cave bear, cave hyena, mammoth, woolly rhinoceros), rock paintings of ancient people (Kapova caves in the Southern Urals, Divya in the Northern Urals, Tuzuksu in the Kuznetsk Alatau, Niah Caves in Malaysia), tools of their labor (villages Strashnaya, Okladnikova, Kaminnaya in Altai), human remains of different cultures, including Neanderthals, up to 50-200 thousand years old (Teshik-Tash cave in Uzbekistan, Denisova cave in Altai, Cro-Magnon in France and many others).

The caves may have played the role of modern cinemas.

Water in the caves

Water, as a rule, is found in many caves, and karst caves owe their origin to it. In the caves you can find condensate films, drops, streams and rivers, lakes and waterfalls. Siphons in caves significantly complicate the passage, require special equipment and special training. Often there are underwater caves. In the entrance areas of the caves, water is often present in a frozen state, in the form of ice deposits, often very significant and perennial.

Air in the caves

In most caves, the air is breathable due to natural circulation, although there are caves in which you can only be in gas masks. For example, guano deposits can poison the air. However, in the vast majority of natural caves, air exchange with the surface is quite intense. The reasons for air movement are most often the temperature difference in the cave and on the surface, so the direction and intensity of circulation depend on the season and weather conditions. In large cavities, the movement of air is so intense that it turns into wind. For this reason, air draft is one of the important features when looking for new caves.

cave deposits

There are mechanical (clay, sand, pebbles, boulders) and chemogenic deposits (stalactites, stalagmites, etc.). In cave systems with an active watercourse, as a rule, mechanical deposits are presented in the form of blocky blockages, often of very large volumes, formed as a result of the collapse of the set of passages, which are formed by the dissolution of the water flow. Blockages are difficult to pass, and dangerous, since the balance of a block blockage is often unstable. Clay deposits are widely represented in the galleries left by an active stream that carried mechanically insoluble rock particles. In the limestone containing the cave, the soluble component is calcium carbonate, which often makes up only about 50% of the rock. The remaining minerals are usually insoluble, and if the water that dissolves the rock is presented in the form of a drop, infiltrate, with a low water flow, unable to provide mechanical transfer of particles, clay deposits begin to accumulate. Very often, ancient passages are completely covered with clay.

Chemogenic deposits (sinter formations) also usually adorn ancient cave galleries, where water, slowly filtering through cracks in limestone, is saturated with calcium carbonate, and when it enters the cavity of the cave, due to a slight change in the partial pressure of water vapor when a drop breaks off, or when when it falls to the floor, or when turbulence occurs when draining, calcium carbonate crystallizes from a saturated solution in the form of calcite.

excursion caves

Some caves are equipped for visiting tour groups (the so-called showcaves). To do this, in the part of the cave, the most spacious and rich in sinter formations, footpaths, ladders, bridges are laid, electric lighting; in some cases, if the entrance part of the cave is a technically difficult area, tunnels are made. In the territory former USSR the most famous caves are Marble in the Crimea, Kungurskaya in the Urals, Novoafonskaya in Abkhazia.

Caves in the solar system

In addition to the Earth, caves have been found on the Moon and Mars. Apparently, these are volcanic caves, ancient traces of volcanic activity.

artificial caves

Caves - dungeons of the industrial world

Under any major city there is a system of technical dungeons: basements of ground buildings, metro, life support system (water supply, heating, sewerage, electrical and telephone cables, fiber optic network), bomb shelters, bunkers in case of war, etc.

Cave - as the dwelling of holy ascetics

Many holy ascetics settled in the caves. Later, monasteries and Lavra were founded on these places:

Kiev-Pechersk Lavra
Pskov-Caves Monastery
Holy Assumption Cave Monastery (Crimea)
Kholkovsky monastery
Chelter Coba
Basarbovsky Monastery
Cave churches in Ivanovo

Holy ascetics who lived in caves:

“And Lot went out of Segor and dwelt in the mountain, and his two daughters with him, for he was afraid to dwell in Segor. And he dwelt in a cave, and his two daughters with him” (Genesis 19:30)
“And the Prophet Elijah went into the cave there and spent the night in it” (1 Kings 19.9)
Hilarion of Kyiv
Anthony Pechersky
Varlaam Pechersky

cave houses

Many peoples made dwellings in caves, as they were easy to keep clean and maintain a constant temperature throughout the year.

Cappadocia
Anasazi
Guadis
Sassi Di Matera

Healing caves

In many medical institutions there are rooms called "salt caves". The walls are lined with potash salt bricks, and patients spend some time in them, listening to music and getting a healing effect.

Entertaining caves

Horror caves are known as a part of amusement parks, cafes and bars, finished under a cave.

Caves in mythology, mysticism and religion.

V. G. Ivanchenko wrote about the symbolic and mystical meaning of the caves in his article “The Sign of the Cave”, published in the journal “Orientation”.

Caves in art, literature and cinematography

Caves appear in many fantastic works (both in fantasy and science fiction). Caves (more precisely, bunkers) in science fiction mainly serve as shelters after a global catastrophe that made life on the surface impossible. And also the caves in fantasy are inhabited by: gnomes, kobolds, goblins, dragons, and in Russian folk tales there lives the "Mistress of the Copper Mountain", Zmey Gorynych. In northern mythology, Sirte live in caves. One of the most famous literary heroes who got into the caves were: Tom Sawyer along with Becky Thatcher, Bilbo Baggins.

underground cavities

In addition to caves that have access to the surface and are accessible for direct study by humans, there are closed underground cavities in the earth's crust. The deepest underground cavity (2952 meters) was discovered by drilling on the coast of Cuba. In the Rhodope Mountains, an underground cavity was discovered at a depth of 2400 meters while drilling. On Black Sea coast in Gagra, underground voids were discovered by drilling at a depth of up to 2300 meters.

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The largest caves are complex systems of passages and halls, often with a total length of up to several tens of kilometers. Caves are an object of study for speleology. Speleotourists make a significant contribution to the study of caves.