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 can be through-holes with several openings 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 water 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.

Moscow State Institute of Steel and Alloys

Vyksa Branch

(University of Technology)

Abstract on the subject

crystal physics

On the topic: "The formation of caves and karsts"

Student: Pichugin A.A..

Groups:MO-07 (MFM)

Teacher: Lopatin D.V.

Moscow 2008

I. General information about caves and karsts

II. Hypothesis about the origin of karst areas

III. Conditions for the formation of caves

IV. Types of caves:

1. Karst caves

2. Tectonic caves

3. Erosion caves

4. Glacial caves

5. Lava cave

V. Caves in the territory of the Baikal region

VI. Cave Kyzylyarovskaya named after. G.A. Maksimovich.

General information about caves and karsts

Karst(from German Karst, after the name of the limestone alpine plateau Kras in Slovenia), - a set of processes and phenomena associated with the activity of water and expressed in the dissolution of rocks and the formation of voids in them, as well as peculiar landforms that arise in areas composed of relatively easily water-soluble rocks (gypsum, limestone, marble, dolomite and rock salt).

Negative landforms are most characteristic of karst. Based on their origin, they are divided into forms formed by dissolution (surface and underground), erosive and mixed. According to morphology, the following formations are distinguished: karrs, wells, mines, dips, funnels, blind karst ravines, valleys, fields, karst caves, underground karst channels. For the development of the karst process, the following conditions are necessary: ​​a) the presence of a flat or slightly sloping surface so that water can stagnate and seep in through cracks; b) the thickness of karst rocks must have a significant thickness; c) The groundwater level should be low so that there is sufficient space for vertical movement of groundwater.

According to the depth of the groundwater level, deep and shallow karst are distinguished. There is also a distinction between “bare” or Mediterranean karst, in which karst relief forms are devoid of soil and plant cover (for example, the Crimean Mountains), and “covered” or Central European karst, on the surface of which the weathering crust is preserved and soil and plant cover are developed.

Karst is characterized by a complex of surface (craters, quarries, trenches, basins, caverns, etc.) and underground (karst caves, galleries, cavities, passages) relief forms. Transitional between surface and underground forms are shallow (up to 20 m) karst wells, natural tunnels, shafts or failures. Karst sinkholes or other elements of surface karst through which surface water flows into the karst system are called ponors.

Karst, limestone plateaus - a complex of irregularities, convex outcrops of rocks, depressions, caves, disappeared streams and underground drains. Occurs in water-soluble and weathered rocks. The process is typical for limestone, as well as for those places where rocks are washed out. Many rivers are underground, there are also many caves and large caverns. The largest caves can collapse and form a gorge or gorge. Gradually all the limestone can be washed away. The phenomenon is named after the Karst plateau in the former Yugoslavia. Characteristic karst systems are widely represented in the Crimean mountains and in the Urals.

Karst can be observed in the Western Alps, in the Appalachians (USA) and in southern China because the limestone layers, which first consisted of a layer of calcite (calcium carbonate), up to 200 m thick, which was partially eroded by water. Carbon dioxide from the atmosphere was dissolved in rain and contributed to the formation of weak carbonic acid, which in turn contributed to the erosion of rocks, especially along cleavage lines and layers, increasing them to the formation of karst caves, valleys that arose as a result of the collapse of cave walls, which, when further development process can turn into gorges, and finally, the remains of limestone that have not been eroded, characteristic of a karst landscape, remain.

Cave- a natural cavity in the upper layer of the earth's crust, communicating with the surface of the earth by one or more exit openings passable for humans. 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.

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

HYPOTHESIS ON THE ORIGIN OF KARST REGIONS

Namely, there is a hypothesis that:

In ancient times, 300-400 million years ago, in sea water there was a process of growth and death of living organisms that intensively used calcium to build their shells. The water was a saturated solution of calcium carbonate. Dead shells sank to the bottom and accumulated along with sediments precipitating out of solution as a result of climatic changes;

Over millions of years, limestone mass accumulated at the bottom in layers;

Under pressure, the limestone sediment changed its structure, turning into stone lying in horizontal layers;

At the moment of shifts in the earth's crust, the sea receded, and the former bottom became dry land;

Two scenarios for the development of events were possible: 1) the layers remained almost horizontal and undisturbed (as near Moscow); 2) the bottom protruded, forming mountains, while the integrity of the limestone layers was violated, numerous transverse cracks and faults formed in them. This is how the future karst region was formed.

This hypothesis is confirmed by the finds of the remains of ancient shells and other former living organisms in the thickness of limestones. Be that as it may, it is obvious that the caves and the rocks where they form are closely connected with ancient life on Earth.

CONDITIONS FOR THE FORMATION OF CAVES

There are three main conditions for the formation of karst caves:

1. The presence of karst rocks.

2. The presence of mountain building processes, movements of the earth's crust in the zone of distribution of karst rocks, as a result - the presence of cracks in the thickness of the massif.

3. Presence of aggressive circulating waters.

Without any of these conditions, cave formation will not occur. However, these necessary conditions may be superimposed by local features of the climate, the relief structure, and the presence of other rocks. All this leads to the appearance of caves of various types. Even in one cave there are various "composite" elements that are formed in different ways. The main morphological elements of karst caves and their origin.

Morphological elements of karst caves:

Vertical abysses, shafts and wells,

Horizontally inclined caves and meanders,

Labyrinths.

These elements arise depending on the type of disturbances in the thickness of the karst massif.

Types of violations:

Faults and faults, cracks:

bedding,

On the border of karst and non-karst rock,

Tectonic (usually transverse),

The so-called lateral resistance cracks.

Scheme of the formation of vertical elements of caves (wells, mines, abysses): Leaching.

Wells are formed at the intersection of tectonic cracks - in the most mechanically weak point of the massif. This is where precipitation water is absorbed. And slowly dissolves the limestone; over millions of years, water expands cracks, turning them into wells. This is a zone of vertical circulation of groundwater

Nival wells (from the surface of the massif):

In winter, the cracks are clogged with snow, then it slowly melts, this is aggressive water, it intensively erodes and expands the cracks, forming wells from the surface of the earth.

Formation of horizontally inclined moves:

Water, penetrating through the layer (layer) of karst rock, reaches the bedding crack and begins to spread along it along the plane of the "fall" of the layers. There is a process of leaching, a subhorizontal course is formed. Then the water will reach the next intersection of tectonic cracks and again a vertical well or ledge will form. Finally, the water will reach the boundary of karstic and non-karstic rocks and then spread only along this boundary. Usually an underground river is already flowing here, there are siphons there. This is a zone of horizontal circulation of groundwater.

Hall formation.

The halls are found in fault zones - large mechanical disturbances in the massif. The halls are the result of alternating processes of mountain building, leaching, and mountain building again (earthquakes, landslides).

It happens that additional mechanisms are included:

Mechanical removal of rock fragments by water flows,

Action of pressure thermal waters (New Athos cave).

Karst caves– these are underground cavities formed and thicker than the earth’s crust, in areas where easily soluble carbonate and halogen rocks are distributed, subject to leaching and mechanical stress, these rocks are gradually destroyed, which leads to the formation of various karst forms. Among them, the greatest interest is caused by underground karst forms - caves, mines and wells, sometimes characterized by a very complex structure. One of the main conditions formation of karst caves is the presence of karst rocks characterized by significant lithological diversity. Among them are carbonate rocks (limestones, dolomites, chalk, marbles), sulfate rocks (gypsum, anhydrites) and halide rocks (rock salts, potassium salts). Karst rocks are very widespread. In many places they are covered by a thin cover of sandy-clay deposits or directly come to the surface, which favors the active development of karst processes and the formation of various karst forms. The intensity of karst formation is also significantly influenced by the thickness of the rocks, their chemical composition and features of occurrence.

Water is the builder of karst caves

As already mentioned, the builder of karst caves is water. However, in order for water to dissolve rocks, they must be permeable, that is, fractured. Rock fracturing is one of the main conditions for the development of karst. If a carbonate or sulphate massif is monolithic and consists of solid rock varieties devoid of fracturing, then it is not affected by karst processes. However, this phenomenon is rare, since limestones, dolomites and gypsums are fissured in nature. Cracks that cut through limestone massifs have a different origin. Highlight cracks lithogenetic, tectonic, mechanical unloading and weathering. The most common are tectonic cracks, which usually cut through different layers of sedimentary rocks, without refracting during the transition from one layer to another and without changing their width. Tectonic fracturing is characterized by the development of complex mutually perpendicular cracks 1–2 mm wide. Rocks are characterized by the greatest fragmentation and fracturing in zones of tectonic disturbances. Falling on the surface of a karst massif, atmospheric precipitation penetrates deep into this massif through cracks of various origins. Circulating through underground channels, water leaches the rock, gradually widens the underground passages and sometimes forms huge grottoes. Moving water is the third prerequisite for the development of karst processes. Without water, which dissolves and destroys rocks, there would be no karst caves. That is why the features of the hydrographic network and the peculiarity of the hydrogeological regime largely determine the degree of trickiness of the karst strata, the intensity and conditions for the development of underground cavities.

Rain and melt snow water

The main role in the formation of many karst cavities is played by infiltration and inflation rain and snowmelt waters. Such caves are corrosion-erosion origin, since the destruction of the rock occurs both due to its chemical leaching and by mechanical erosion. However, one should not think that these processes proceed simultaneously and continuously. At different stages of the development of caves and in different parts of them, one of these processes usually dominates. The formation of some caves is entirely associated with either corrosion or erosion processes. There are also nival-corrosion caves, which owe their origin to the activity of melted snow waters in the zone of contact between the snow mass and karst rock. These include, for example, relatively shallow (up to 70 m) vertical cavities in the Crimea and the Caucasus. Many caves arose as a result of the collapse of the roof over underground corrosion-erosion voids. Some natural cavities were formed by leaching of rocks by artesian, mineral and thermal waters ascending along cracks. Thus, karst caves can be of corrosion, corrosion-erosion, erosion, nival-corrosion, corrosion-gravity (failure), hydrothermal and heterogeneous origin.

condensation water

In addition to infiltration, inflation and pressure waters, condensation waters also play a certain role in the formation of caves, which, gathering on the walls and ceiling of caves, corrode them, creating bizarre patterns. Unlike underground streams, condensation waters affect the entire surface of the cavity, and therefore have the greatest impact on the morphology of the caves. Particularly favorable conditions for moisture condensation are characterized by small cavities located at a considerable depth from the surface, since the amount of condensation moisture is directly dependent on the intensity of air exchange and inversely on the volume of the cavity. The observations made in , showed that in

Karst caves are underground cavities formed in the thickness of the earth's crust, in areas where readily soluble carbonate and halogen rocks are distributed. Being subjected to leaching and mechanical impact, these rocks are gradually destroyed, which leads to the formation of various karst forms. Among them, the most interesting are underground karst forms - caves, mines and wells, sometimes characterized by a very complex structure.

One of the main conditions for the development of karst caves is the presence of karst rocks, characterized by significant lithological diversity. Among them are carbonate rocks (limestones, dolomites, chalk, marbles), sulfate rocks (gypsum, anhydrites) and halide rocks (rock salts, potassium salts). Karst rocks are very widespread. In many places they are covered by a thin cover of sandy-clay deposits or directly come to the surface, which favors the active development of karst processes and the formation of various karst forms. The intensity of karst formation is also significantly influenced by the thickness of the rocks, their chemical composition and features of occurrence.

As already mentioned, the builder of karst caves is water. However, in order for water to dissolve rocks, they must be permeable, that is, fractured. Rock fracturing is one of the main conditions for the development of karst. If a carbonate or sulphate massif is monolithic and consists of solid rock varieties devoid of fracturing, then it is not affected by karst processes. However, this phenomenon is rare, since limestones, dolomites and gypsums are fissured in nature. Cracks that cut through limestone massifs have a different origin. Allocate cracks lithogenetic, tectonic, mechanical unloading and weathering. The most common are tectonic cracks, which usually cut through different layers of sedimentary rocks, without refracting during the transition from one layer to another and without changing their width. Tectonic fracturing is characterized by the development of complex mutually perpendicular cracks 1-2 mm wide. Rocks are characterized by the greatest fragmentation and fracturing in zones of tectonic disturbances.

Falling on the surface of a karst massif, atmospheric precipitation penetrates deep into this massif through cracks of various origins. Circulating through underground channels, water leaches the rock, gradually widens the underground passages and sometimes forms huge grottoes. Moving water is the third prerequisite for the development of karst processes. Without water, which dissolves and destroys rocks, there would be no karst caves. That is why the features of the hydrographic network and the peculiarity of the hydrogeological regime largely determine the degree of cavernousness of the karst strata, the intensity of leaching processes, and the conditions for the development of underground cavities.

The main role in the formation of many karst cavities is played by infiltration and inflation rain and snowmelt waters. Such caves are of corrosion-erosion origin, since the destruction of the rock occurs both due to its chemical leaching and mechanical erosion. However, one should not think that these processes proceed simultaneously and continuously. At different stages of the development of caves and in different parts of them, one of these processes usually dominates. The formation of some caves is entirely associated with either corrosion or erosion processes. There are also nival-corrosion caves, which owe their origin to the activity of melted snow waters in the zone of contact between the snow mass and karst rock. These include, for example, relatively shallow (up to 70 m) vertical cavities in the Crimea and the Caucasus. Many caves arose as a result of the collapse of the roof over underground corrosion-erosion voids. Some natural cavities were formed by leaching of rocks by artesian, mineral and thermal waters ascending along cracks. Thus, karst caves can be of corrosion, corrosion-erosion, erosion, nival-corrosion, corrosion-gravity (failure), hydrothermal and heterogeneous origin.

In addition to infiltration, inflation and pressure waters, condensation waters also play a certain role in the formation of caves, which, gathering on the walls and ceiling of caves, corrode them, creating bizarre patterns. Unlike underground streams, condensation waters affect the entire surface of the cavity, and therefore have the greatest impact on the morphology of the caves. Particularly favorable conditions for moisture condensation are characterized by small cavities located at a considerable depth from the surface, since the amount of condensation moisture is directly dependent on the intensity of air exchange and inversely on the volume of the cavity. Observations carried out in the Crimean Mountains showed that 3201.6 m 3 of water condenses in the studied karst caves during the year (Dublyansky, Ilyukhin, 1971), and in the underground cavities of the entire main ridge 2500 times more (i.e. 0, 008004 km 3). These waters are highly aggressive. Their hardness exceeds 6 mEq (300 mg/l). Thus, due to the infiltration waters of the cave Mountain Crimea, as simple calculations show, increase by about 5.3% compared to the total volume. The average mineralization of condensation waters is about 300 mg/l, therefore, they carry out 2401.2 tons (8004 10 6 l X 300 mg/l) of calcium carbonate during the year. The total removal of calcium carbonate by karst springs in the Crimean Mountains is about 45,000 tons/year (Rodionov, 1958). Consequently, the role of condensation waters in the formation of underground cavities is relatively small, and their impact on the rock as a denudation agent is limited mainly to the warm period.

How does the process of leaching of karst rocks proceed? Let us consider this issue in general terms using the example of carbonate formations. Natural waters always contain carbon dioxide, as well as various organic acids, with which they are enriched upon contact with vegetation and seepage through the soil cover. Under the action of carbon dioxide, calcium carbonate is converted to bicarbonate, which is much more readily soluble in water than carbonate.

This reaction is reversible. An increase in the content of carbon dioxide in water causes the transition of calcite into solution, and with a decrease in it, precipitation of calcium bicarbonate (lime sediment) from an aqueous solution occurs, which accumulates in some places in a significant amount. There is an inverse relationship between carbon dioxide content and water temperature.

The solubility of limestones increases sharply when groundwater is enriched with acids and salts. Thus, when groundwater is enriched with sulfuric acid, the reaction proceeds according to the equation

The carbon dioxide released as a result of this reaction is an additional source of hydrocarbonate formation.

The degree of solubility of gypsum and anhydrite also depends on the presence of certain acids and salts. For example, the presence of CaCl 2 in water significantly reduces the solubility of gypsum, on the contrary, the presence of NCl and MgCl 2 in water increases the solubility of calcium sulfate. The dissolution of gypsum can, in principle, also occur in chemically pure water.

Although we call carbonate and sulfate rocks easily soluble, they dissolve extremely slowly. It takes many, many thousands of years for underground voids to form. At the same time, karst rocks dissolve and collapse only along cracks; outside the cracks, they remain very strong and hard as before.

Atmospheric waters penetrating into karst massifs through cracks and tectonic disturbances are initially characterized by predominantly vertical movement. Having reached the aquitard or local erosion base, they acquire horizontal movement and usually flow along the dip of the rock layers. Part of the water seeps into deep horizons and forms a regional runoff. In this regard, several hydrodynamic zones are distinguished in the karst massif, namely the zone of surface, vertical, seasonal, horizontal, siphonic and deep circulation of karst waters (Fig. 1). Each of these hydrodynamic zones is characterized by a certain set of karst forms. Thus, mainly vertical underground cavities - karst wells and mines - are confined to the zone of vertical water circulation or the aeration zone. They develop along vertical or gently inclined cracks as a result of periodic leaching of rocks by melted snow and rainwater. In the zone of horizontal circulation, where there is a free flow of free-flowing water to river valleys or the periphery of the karsting massif, horizontal caves are formed. Inclined and horizontal cavities are observed in the zone of siphon circulation, characterized by pressure waters that move in sub-channels often below the local erosion base.

The development of caves, in addition to morphostructural and hydrogeological features, is also significantly influenced by climate, soil, vegetation, animal world and human economic activity. Unfortunately, the role of these factors in cave formation is currently far from sufficiently studied. It is to be hoped that this gap will be closed in the near future.

The theory of the origin of limestone karst caves developing in rocks with horizontal layers was developed by W. M. Davis (1930). In the evolution of the so-called two-cycle caves, formed during the double uplift of the limestone massif, he distinguished five main stages: a) embryonic channels formed in the zone of complete saturation of slowly moving phreatic waters under pressure; b) mature galleries, when mechanical erosion (corrosion) begins to dominate under the conditions of the spread of free-flow vadose flows; c) dry galleries that arose as a result of water moving deeper into the massif due to local uplift of the territory; d) sinter-accumulative, characterized by the filling of galleries with sinter-drop and other cave deposits; e) destruction of underground galleries (peneplanization).

On the basis of the development of Davis's views, an idea was created about the phreatic (cave galleries are developed by groundwater under pressure) and vadose (groundwater freely, not under pressure, moves along the galleries towards drainage systems) stages of cave development (Bretz, 1942).

The questions of the evolution of underground cavities were most fully developed by Soviet researchers G. A. Maksimovich (1963, 1969) and L. I. Maruashvili (1969), who identified several stages in the formation of horizontal karst caves. The first stage is fissure, then crevice. As the width of cracks and crevices increases, an increasing amount of water penetrates into them. This activates karst processes, especially in areas of pure rock differences. The cave passes into the canal stage. With the expansion of channels, underground flows acquire turbulent motion, which favors an even greater increase in the processes of corrosion and erosion. This is the stage of the underground river, or vokluzovaya. It is characterized by a significant filling of the underground channel with a water stream and its exit in the form of an open source to the day surface, as well as the formation of organ pipes, the collapse of vaults, and the growth of grottoes.

Due to the erosion of the bottom of the underground channel, water seeps through cracks into the depths of carbonate and halogen strata, where it develops new cavities at a lower level, forming the lower floor of the cave (Fig. 2). Gradually, underground channels expand. The water flow partially and then completely goes into the lower horizons of the massif, and the cave becomes dry. Only infiltration water penetrates into it through cracks in the roof. This is a corridor-grotto scree-scree (water-gallery, according to L.I. Maruashvili) stage of cave development. It is distinguished by a wide distribution of chemical and mechanical accumulation (in gypsum caves, the stage of sinter accumulation is absent). The ceiling and walls of the cave are covered with various calcite deposits. Stone and earthen "talus" are formed, the latter are located mainly under the organ pipes. Sediments of rivers and lakes also accumulate. With the departure of the watercourse, the further increase in the underground cavity slows down sharply, although the corrosive activity continues due to infiltration and condensation waters.

As the cave develops, it passes into the corridor-grotto landslide-cementation (dry-gallery, according to L.I. Maruashvili) stage. At this stage, as a result of the collapse of the roof over the underground cavities, it is possible to open some parts of the cave. The gradual collapse of the cave roof leads to its complete destruction, which is especially typical for the upper parts with a small roof thickness. In the surviving areas, only karst bridges and narrow arches remain. With the complete destruction of the cave, a karst valley is formed.

If the thickness of the roof exceeds 100-200 m, then, as a rule, no dips are formed in it, and underground cavities are filled with blocks of rock that have fallen from the ceiling and brought sandy-argillaceous deposits, which break the cave into separate isolated cavities. In this case, the development of the cave ends with a corridor-grotto landslide-cementation stage (grotto-chamber stage, according to L. I. Maruashvili).

The duration of individual stages of the cave-forming cycle, which differ in their hydrodynamic and morphological features, the specifics of physicochemical processes and the peculiarity of bioclimatic conditions, is measured in tens and hundreds of millennia. Thus, the dry-gallery stage of the Kudaro Cave in the Caucasus has been going on for 200-300 thousand years (Maruashvili, 1969). As for the early stages of cave development (fissure, slit, channel and vault), their duration is much shorter. Caves "may reach a mature water-gallery state several millennia from the initial moment of their development." In this regard, experimental studies by E. M. Abashidze (1967) on the dissolution of crack walls in glauconite limestones of the Shaori reservoir (Caucasus) are of interest. Experiments have shown that for 25 years of continuous filtration, depending on the flow rate, hairline cracks of 0.1-0.25 mm in size can increase to 5-23 mm.

Thus, karst caves are characterized by a complex evolution, the features of which depend on a combination of various factors that often determine significant deviations from the considered scheme. The development of caves, for one reason or another, can stop or start again at any morphological and hydrological stage. Complex cave systems usually consist of sites at different stages of development. So, in the Ischeevskaya cave in the Southern Urals, there are now sections from the canal stage to the karst valley.

A feature of many caves is their multi-tiered, and the upper tiers are always much older than the underlying ones. The number of floors in different caves varies from 2 to 11.

The distance between two adjacent levels of multi-storey caves ranges from several meters to several tens. The collapse of the arches separating the cave floors leads to the formation of giant grottoes, sometimes reaching a height of 50-60 m (Krasnaya and Anakopiya caves).

G. A. Maksimovich connects the appearance of a new floor with the tectonic uplift of the area where the cave is located. N. A. Gvozdetsky assigns the main role in the development of multi-storey caves in conditions of high thickness of karst rocks to ascending movements, which he considers not as a disturbing factor, but as a general background for the evolution of karst. According to L. I. Maruashvili, the multi-tiered caves can be determined not only by the tectonic uplift of the karst massif, but also by the general lowering of the ocean level (eustasia), which causes an intensive deepening of river valleys and a rapid decrease in the level of horizontal circulation of karst waters.

Layering is best expressed in the caves of the plains and foothills, which are distinguished by relatively slow tectonic uplifts. During the formation of caves, sometimes there is a shift in the axis of cave galleries from the original vertical plane. The Tsutskhvatskaya cave is interesting in this respect. Each younger (of the four lower) tiers of this cave is shifted to the east relative to the previous one, and therefore the underground section of the Shapatagele River is currently located much to the east than during the formation of the higher tiers of the cave. The displacement of the axis of cave galleries is associated with the inclination of tectonic cracks, to which underground cavities are confined.

What is the age of karst caves and by what signs can one judge the beginning of the formation of the cave? According to L. I. Maruashvili, the period of its transition to the scree (water-gallery) stage should be taken as the beginning of the formation of the cave, since at the earlier stages of its development the cave is not yet a cave in the usual sense: it is poorly developed, completely filled water and completely impassable.

Various research methods are used to determine the age of the caves, including paleozoological, archaeological, radiocarbon and geomorphological. In the latter case, the hypsometric level of caves is compared with the levels of surface forms. Unfortunately, many of these methods only provide an upper limit on the age of a cave. Direct and indirect evidence proves the very long existence of karst caves, sometimes determined by many millions of years. Of course, the age of caves largely depends on the lithological composition of the rocks in which they are formed, and the general physical and geographical situation. However, even in easily soluble sulfate (gypsum, anhydrite) formations, caves remain for a very long time. Of interest in this regard are the gypsum caves of Podolia, the beginning of their formation dates back to the Upper Miocene. I. M. Gunevsky, based on the features of the geological structure of the territory, the degree of fracturing of rocks, the nature of the relief, the morphology of underground cavities and the structure of sinter formations, distinguishes the following stages of the formation of Podolsk caves: Upper Sarmatian (the beginning of intense deep erosion), Early Pliocene (characterized by the intensification of processes of the vertical direction ), Late Pliocene (horizontal groundwater circulation processes prevail over vertical ones), Early Pleistocene (cave formation processes reach their maximum intensity), Middle Pleistocene (underground karst formation processes begin to fade), Late Pleistocene (accumulation of mineral and chemogenic formations), Holocene (accumulation of blocky deposits). Thus, the age of the world's largest gypsum caves Optimistic, Ozernaya and Kryvchenskaya in Podolia apparently exceeds 10 million years. The age of limestone caves may be even more significant. So, some ancient karst caves of the Alai Range (Central Asia), which are of hydrothermal origin, according to Z. S. Sultanov, were formed in the Upper Paleozoic time, that is, more than 200 million years ago.

Ancient caves are found, however, relatively rarely, remaining for a long time only in the most favorable natural conditions. Most of the karst caves, especially in heavily watered sulfate rocks, are of young, predominantly Quaternary or even Holocene age. Of course, separate galleries of complexly built multi-tiered caves were formed at different times and their age can vary considerably.

For a quantitative assessment of karst cavities, G. A. Maksimovich (1963) offers two indicators: the density and density of karst caves. Density refers to the number of caves related to an area of ​​1000 km 2, and density is the total length of all cavities within the same conventional area.

J. Korbel proposed to characterize the size of karst caves with an indicator of voidness, calculated by the formula

Where V - the volume of soluble rock in which the cave is developed, in 0.1 km 3; L- distance (on the plan) between the extreme points along the main axis of the system of cavities - 0.1 km; J- the distance between the two most distant points along the perpendicular to the main axis - 0.1 km; H - the difference in marks between the highest and lowest points of the cave system is 0.1 km.

To determine the size of caves, there is also another method, which is associated with the calculation of the volume of cavities. If the cavity has a complex shape, then it should be represented as a set of various geometric shapes (prism, cylinder, full and truncated cone, full and truncated pyramid with a base of any shape, ball, etc.), the volume of which is calculated by the Simpson formula

Where v - the volume of the geometric figure, m 3; h - figure height, m; s1, s2, s3 - areas of the lower, middle and upper sections of the figure, m 2. Verification of this method by Crimean speleologists showed that errors in calculating the volume of cavities using the Simpson formula do not exceed 5-6%.

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: water flow, which 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 ceased to fall into 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.

Recently, more and more caves have been 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 filled 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. Meltwater in such caves can flow both along the glacier bed and over 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 can create voluminous galleries, but such caves do not lie in the glacier itself, but underneath it, since the ice melts from below. Thermal glacial caves are found in Iceland and Greenland and reach significant sizes.

Volcanic caves

These caves appear during volcanic eruptions. The lava flow, as it cools, becomes covered with a hard crust, forming a lava tube, inside which molten rock still flows. After the eruption has actually 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 in length and 1100 m in depth (Kazumura Cave, Hawaiian Islands).

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

Caves by type of host rock

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. There are known caves 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 Gorlo 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 point caves. According to estimates, the maximum depth of the cave passages under the surface (not to be confused with the depth of the cave!) Can be no more than 3000 meters: any cave deeper 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 enters), nevertheless, some animals live in caves or even only in caves. First of all, these are 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.

In addition to bats, several species of insects, spiders (Neoleptoneta myopica), shrimp (Palaemonias alabamae) and other crustaceans, salamanders and fish (Amblyopsidae) live in some caves in warmer climates. Cave species adapt to complete darkness, and many of them lose their organs of vision and pigmentation. These species are often very rare, many of them endemic.

archaeological finds

Prehistoric people used caves all over the world as homes. Even more often, animals settled in caves. Many animals died in the cave-traps, starting from steep wells. The extremely slow evolution of caves, their constant climate, and protection from the outside world have preserved a huge number of archaeological finds to us. 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 served as modern cinemas.

Water in 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. Underwater caves are often found. 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 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 blocked by 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 is created; 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 Dormition 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, the "Mistress of the Copper Mountain", the Serpent Gorynych, lives there. In northern mythology, Sirte live in caves. One of the most famous literary characters who ended up in 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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