Main Caucasian Range

The mountain system of the Caucasus in Russia, Georgia and Azerbaijan. A continuous mountain range extending from west-northwest to east-southeast between the Chyorny and Caspian Seas for almost 1200 km, expanding from 30 to 180 km. Along the watershed of the Greater Caucasus, the border between Europe and Asia is usually drawn.

The highest point of the Caucasus, Russia and Europe is Mount Elbrus (5642 m).

The Greater Caucasus is divided into

• Western (from the Taman Peninsula to Mount Elbrus),
• Central (between the Elbrus and Kazbek mountains) and
• East Caucasus (from Mount Kazbek to the Absheron Peninsula).

Greater Caucasus Ranges

In the north, the Main Caucasian Range borders on the Kuban-Priazovskaya and Tersk-Kum lowlands and the Stavropol Upland, in the south it is separated by the Kolkhida Lowland and the Kurin Depression.

The main Caucasian Range is an asymmetric mountain system with long gentle northern and short steep southern slopes.

The Greater Caucasus forms four parallel ranges for the most part, rising from north to south step by step.

The smallest Pasture Range, it is also called the Black Mountains with heights up to 1,500 meters. Behind it grows the Rocky Ridge up to 2000-2500 meters high). These two ridges are cueste ridges, with a gentle northern and steep southern slope.

After the Rocky, the Lateral, or Front Ridge with heights of 4000-5000 meters rises, it is on it that 7 peaks above 5000 meters are located, including Elbrus (5642 meters), Dykh-Tau, Kostan-Tau, Kazbek (5033 meters) and other peaks.

With narrow Arkhyzsk-Zagedanskaya, Bezhetinskaya and other depressions, the Lateral Ridge is separated from the Main, or Dividing Ridge. The highest and rocky section of the Main, or Dividing, ridge is the Bezengi Wall.

The narrow southern slope of the Greater Caucasus is replaced by the Transcaucasian Depression, which consists of the Rionian or Colchis Depression, and the Kurin Depression. Between the depressions is a narrow Suram or Likh ridge.

In the east, the complex and diverse relief of Dagestan is dominated by plateaus, for example Gunib and folded ridges.

For most of the southern slope of the Greater Caucasus, short erosion-denudation ridges are typical, composed mainly of limestones.

In the West Caucasus - Kodorsky, Svanetsky, Rachinsky and other (height up to 4000 m) ridges. In the East Caucasus, the southern slope is very narrow and steep with deep river valleys and large carry cones.

In the relief of the Greater Caucasus, there are many forms associated with active exogenous processes, including catastrophic ones. In the highlands - avalanche, mudflows, permafrost; in the middle mountains - landslide-crayfish, landslide, in the low mountains - erosion. Karst is developed in carbonate rocks, especially on the southern slope. In Russia, the most famous are the Vorontsov Cave, in Abkhazia - the New Athos Cave and the Snow Abyss.

Abrasion and landslides (including seismic landslides) are active on the Black Sea coast of the Caucasus. Mud volcanoes are typical in the eastern edge parts of the Main Caucasus Range.

The history of the formation of the mountains of the Caucasus

Main article: The history of the Earth before the appearance of hominids

About 390 million years ago, three large plates - Lawrence, Baltic and Sibiria - successively collided with each other, connecting to a large continent - Laurasia. At the same time, Laurasia itself was approaching Gondwana, a huge continent in the South Pole. Between them narrowed the ancient ocean Paleotetis. Colliding, Laurasia and Gondwana formed a huge single supercontinent of Pangea, within which the Paleothetis Ocean continued to narrow.

The movement of the Paleotetis plate pressed on the edge of the Pangea in the area of ​ ​ the northern edge of the ocean (Russian platform) - in the place where the Caucasus is now located. This pressure led to the formation of ancient mountains on the site of the Caucasus.

The mining structure did not last long by geological standards, and about 250 million years ago only the base crumpled into folds remained of it. This foundation was called the Scythian Platform; it adjoins the Russian platform from the south.

To the south, the extension of the Tethys Ocean shifted several continental plates to the north. These plates crept onto the oceanic crust of Paleotetis.

During the Triassic period (250-200 million years ago), the supercontinent Pangea begins to split into separate plates, which will later turn into the continents we know. The African Plate began to separate first - from the Eurasian and then North American Plate, thereby giving rise to the Atlantic Ocean.

At the beginning of the Jurassic period, about 200 million years ago, the collapse of the Pangea supercontinent continues. Still connected to each other, and break off from it Antarctica Australia. In the area of ​ ​ India the modern Caucasus at that time, due to the increase in world ocean level, the Scythian platform was almost completely covered with water. At the bottom of the sea, clays are first deposited, and later limestones consisting of the remains of marine plants and animals, such as shells, accumulate.

Where the oceanic crust of the Tethys Ocean pushed hard under the edge of the Scythian Plate, there was a weakening of this edge. This is due to the fact that the ocean plate, going down, melts, and the excess of molten matter tries to break up.

Rifting began to occur on the weakened edge of the plate - the formation of rifts with the extension of the split fragments of the previous base. The new crust was expanding toward the ocean. The crust was generally continental, granite, but broken by outpourings of basalts. So (at the end of the Lower and beginning of the Middle Jurassic, something about 175 million hp) the so-called Big Caucasus basin was formed. It was a marginal sea. It was separated from the main ocean of Tethys by an island volcanic arc, the existence of which is also explained by the weakening of the lithosphere in the subduction zone, the sub-wave, and the breakthrough of magma to the surface with the formation of volcanoes. The Big Caucasus Basin was extended 1700-1800 km long and 300 km wide^[1] of^[2].

Three depressions are successively formed behind island arcs: West and East Black Sea and South Caspian. We can say that in the Cretaceous period (145-65 million years ago) the Black Sea was born and the process of raising the Caucasus Mountains began.

In the Cretaceous period, the disintegration of Pangaea continues. It has already divided into three major continents: this is North America with Eurasia; Africa with South America; Antarctica with Australia and India. And there are already splits between North America and Eurasia, and between Africa and South America.

The split of the Pangaea into South America and Africa (with Arabia) led to an increase in the oceanic lithosphere between them and, very importantly for the Caucasus, to a reduction in the distance between Africa and Eurasia. The Tethys Ocean began to shrink in size.

About 70 million years ago, the Mediterranean folded belt was formed in its modern form. It separates the southern group of ancient platforms, which constituted the supercontinent Gondwana until the middle of the Jurassic period, from the northern group, which formerly constituted the continent of Laurasia and the Siberian platform.

This belt includes the southern regions of Europe, Northwest Africa, Alps, Carpathians, Crimea, Caucasus, Persian mountain systems, Kopet Dag, Pamir, Himalayas, Tibet, Indochina and Indonesian islands.

By the end of the Cretaceous period (65 million years ago), Pangea finally disintegrates into continents already familiar to us. The Atlantic Ocean expands and lengthens to both north and south. India and Australia are breaking away from Antarctica. In the place of the Caucasus, there is still a shallow sea, separated from the ocean by an island arc. Limestones, sands and clays continue to accumulate in this sea.

By the middle of the Paleogene epoch (about Z0 Ma), Africa, with its northeastern edge - the Arabian Plate - collided with the Eurasian continent. As a result of this collision, the size of the Big Caucasus basin first decreased, an island arc with volcanoes approached the continent. Mount Ararat is one of these volcanoes.

When the Great Caucasus Basin completely contracted and the pressure of the Arabian Plate did not weaken, the rocks of the plate edge began to shrink into folds and extruded up - the process of raising the Caucasus mountains began.

In the last period (12 million years ago to the present), the pressure of the Afro-Arabian platform continues unabated. Throughout this period, the Caucasus continued to rise. Moreover, under conditions of monstrous compression, volcanism intensified. 7 million years ago, a mass of volcanoes formed both in the Small Caucasus and later within the Greater Caucasus. The largest mountain in Europe is Elbrus, a volcano that formed at least 2 million years ago.

Now we see the result of the action of the geological processes described above. In the West Caucasus, in that number in the Sochi region, the tops of the mountains are composed of ancient crystalline rocks by the remains of parts of ancient plates squeezed onto the surface. These rocks are framed by marine rocks of Jurassic, Cretaceous and Paleogene ages. Rocks formed at the bottom of the sea by the force of collision of plates were raised to a height of several kilometers. This is why marine shells can be found high up in the mountains.

Earthquakes in the Caucasus

The movement of the plates continues in our time. Due to the pressure of the Afro-Arabian Plate on the Scythian Platform, rocks are compressed and squeezed upward to form mining structures, and the lower denser part of the plate probably moves under the Scythian Platform and goes deep into the mantle. Some of the plate's substance at depth melts and rushes up to the surface. If molten magma reaches the surface, a volcano forms.

Due to all these processes, earthquakes often occur in the Caucasus, which are distinguished by the shallow depth of the focus and great destructive force. The area of ​ ​ maximum shaking (earthquake epicenter) can be measured by tens of kilometers. The tremors of such earthquakes occur due to the sudden release of stress arising from the processes of mountain formation, which have a large pressure in the center. Discharge in this case occurs when the earth's crust is displaced or faults form.

In order to protect himself from danger, a person began to observe the shocks of the earth's crust and the harbingers of earthquakes. The first instrumental observations of earthquakes began in the Caucasus in 1902 in Azerbaijan, where three seismic recording stations were installed that controlled seismicity at oil production sites. Later, during the USSR, a dense network of seismological stations was organized, registering harbingers earthquakes, which made it possible to predict their development. For 2023 in the Caucasus 94 active seismic stations. Thanks to their work, most of the earthquakes that occurred were predicted and assistance was provided in time to eliminate their consequences.

Climate

The main Caucasian ridge is an important climatic barrier on the path of cold air masses from the north and warm from the south, moisture-bearing air masses from the west and dry from the east. The diversity and contrast of climates are due to the position on the border of the temperate and subtropical climatic zones, the sub-latitudinal strike of the mountain system, high heights, the exposure of slopes and the variety of terrain. In the highlands, the climate is cold and humid, in the middle mountains and low mountains - moderate, in the lower parts of the southern slope of the Western Caucasus - subtropical humid, northwest of Tuapse - Mediterranean, in the East Caucasus - subtropical dry. The average annual temperature at the foot of the northern slope is 10 ° C, at the southern 16 ° C, above 2400-2800 meters - negative, at an altitude of 4250 meters drops to -10.2 ° C. Exposure differences are better expressed in winter. The average January temperature at the foot varies from -3.5 and -5 ° C in the north to 6 ° C in the south, at an altitude of 2000 meters about -8 ° C; in the highlands (4250 meters, Elbrus weather station) -19 ° С. The average July temperature at the foot rises from 22-24 ° C in the west to 25-27 ° C in the east, the temperature of August (the warmest month) decreases in the middle mountains to 10-13 ° C, in the highlands to 1 ° C.

Along the foot of the northern slope, precipitation falls from 400-600 mm in the west to 300-400 mm in the east, at altitudes of more than 2000 meters, respectively, from 2000-2500 mm to 800-1150 mm. Dry (300-500 mm) is distinguished by intermountain basins and the southern slopes of ridges located in the "rain shadow." The most humidified southwestern slopes are up to 3500 mm (3682 mm, Achishkho weather station at an altitude of 1880 meters, the wettest place in Russia). Along the foot of the southern slope, rainfall increases per year from west to east from 500-800 mm to 1200-1600 mm in the center, and decreases to 200 mm in the extreme east.

The snow border rises to the east from 2500 meters to 3600 meters. In the highlands, powerful modern glaciation is developed (2050 glaciers, with an area of ​ ​ 1426 km2); 70% - on the northern slope. Just over half of the glaciers are concentrated in the Central Caucasus; the largest - Bezengi (17.6 km - one of the longest glaciers in Russia), Dykhsu, Karaug, Lekziri, etc. A large center of glaciation is Mount Elbrus (area 124.9 km2, 2005). Pulsating glaciers are peculiar - Devdorak, Kolka, known for periodic, including catastrophic, movements and gatherings (the latter occurred in Russia, in the Karmadon Gorge, Kolka Glacier, 2002).

Water resources

The rivers belong to the basins of the Chyorny (Mzymta, Bzyb, Rioni, Inguri, etc.), Caspian (Kura, Terek, Kuma, etc.) and Azovsky (Kuban) seas. The density of the river network is uneven, most developed in the west, especially on the southern slope, in the highlands and mid-mountains. Mountain rivers with a high flow rate (do not freeze in winter), with sharp fluctuations in runoff (winter low water), rapids and waterfalls. Often flow along picturesque canyon-like gorges. The annual flow of rivers is 79 km3, including 29.6 km3 on the northern slope, and 49.4 km3 on the southern slope. River flow decreases from west to east and with a decrease in height. River nutrition is mainly mixed with flood in the warm period of the year, in the west often with floods. Many rivers are selenary. The transport significance of the rivers is small, in the lower reaches navigable Kura, Rioni, Kuban. A large number of rivers are used for irrigation, hydroelectric power stations were built (Baksanskaya, Gizeldon, Inguri hydroelectric power plants, etc.).

There are many lakes of various origins in the Great Caucasus: glacial (Baduk, Klukhorskoye in the river basin Teberda, Bashkara in the river basin Baksan, etc.), karst (Blue in the valley of the river Cherek, etc.), tectonic - Abrau and Ritsa (one of the most picturesque). The lakes are small in area, but deep enough.

Landscapes

The Main Caucasus Range is characterized by various landscapes with the dominance of mountain-forest and mountain-meadow. Altitude zonation is clearly manifested, which varies depending on the exposure of macrosclones and longitude. The greatest differences in the structure of the altitudinal zonation are characteristic of the lower parts of the slopes. On the northern slope of the West Caucasus

• in the foothills, small areas occupy steppe landscapes on chernozems (up to 450-500 meters), replaced by forest-steppe areas with meadow steppes on chernozems and oak forests on gray forest soils;
• above (600-800 meters) - mountain-forest landscapes with low-mountain broadleaf (oak and hornbeam-oak) and medium-mountain (beech) forests on shrews and sod-carbonate soils;
• at an altitude of 1300-1600 meters - mixed and coniferous (beech-spruce and spruce-fir) forests on shrews and podzolic soils.

At the upper border of the forest (2000-2300 meters), a belt of birch, less often beech and maple, crooked forests is developed. Mountain-meadow landscapes are typical for highlands: tallgrass subalpine (with thickets of Caucasian rhododendron) on turf soils and alpine low-grass meadows (at an altitude of 2500 meters) on alfegumus soils. Above them is a subnival belt with fragmentary vegetation on primitive soils. Above 3300 meters - glacial-nival landscapes.

On the southern slope of the Western Caucasus, the structure of high-rise belts is similar, only in the foothills up to a height of 600 meters subtropical broad-leaved forests of the Colchis type are formed, polydominant (from chestnut, oak of Georgia and Hartvis, beech) with evergreen undergrowth (holly, rhododendron Pontic, laurel, boxwood) and lyans (Colchis ivy) on yellow trees, less often red trees; sod-carbonate soils are common. Of the coniferous species, berry yew is found. Northwest of Tuapse - Mediterranean forests (fluffy oak, false pistachio, high juniper) and shrubs on sod-carbonate and brown soils.

On the northern slope of the East Caucasus, dry-steppe landscapes prevail in the lower parts, with shiblyak and frigana on chestnut soils, less often brown, at an altitude of 800-2000 meters - low-mountain and middle-mountain steppe and meadow-steppe landscapes on chernozems. The mountain-forest zone with pine forests is fragmented.

On the slopes facing the Caspian Sea, at an altitude of 600-1200 meters, there are sections of broad-leaved forests (with oak, hornbeam) on shrews. For highlands, mountain meadows with xerophytic elements on turf and alfegumus soils are typical. The glacial-nival zone begins higher (3800-3900 meters) than in the Western Caucasus.

On the southern slope of the East Caucasus in the extreme east, foothill semi-deserts are developed, at an altitude of about 300 meters - low-altitude arid woodlands and thickets of shiblyak on brown soils, in the middle mountains - broad-leaved forests (from oak of eastern and Georgian, hornbeam, beech) with the participation of Hyrkan relict species (majestic maple, danaya shrub) on shrews; above are mountain-meadow landscapes with subalpine and alpine meadows on alfegumus soils; in some places - glacial-nival landscapes.

There are many rare and relict species in the diverse flora and fauna of the Greater Caucasus, including up to 30% endemic to the plant world. Among the animals endemic are the Caucasian tour, ular, black grouse, promethean vole, etc. Typical forest species are wild boar, brown bear, fox, dormouse-shelf. The population of the bison that previously lived here has been restored. Sulfur, tours, alpine jackdaw, snow vole, etc., are common in the highlands.

The landscapes of the Main Caucasus Range are changed by man, especially foothill and low-mountain steppe and subtropical forest. The landscapes of the East Caucasus are severely disrupted.

Resorts

Picturesque mountain and seaside landscapes are attractive for recreation, highland landscapes are attractive for skiing and mountaineering (Elbrus region, Dombai, Arkhyz, Krasnaya Polyana, Rosa Khutor, etc.).

The Black Sea coast of the Caucasus is an area of ​ ​ popular climatic (Anapa, Gelendzhik, Sochi, etc.) and balneological (Matsesta) resorts.

Protected Natural Areas

To protect typical and unique natural landscapes, reserves have been created, the most famous -

• Caucasian and Teberdinsky (both biospheric),
• Kabardino-Balkarian (all in Russia),
• Lagodekhsky (one of the first in the Caucasus, 1912) and Ritsinsky (both in Georgia), etc.

National parks - Sochi, Elbrus (both in Russia), etc.

Among the natural monuments is the karst massif "Stone Sea" (Lagonaki plateau, Western Caucasus). The Caucasus Reserve, Sochi National Park and other territories are included in the World Heritage List.

Notes