Ocean Tethys history. Where the Tethys ocean was

Many millions of years ago, on the site of Crimea, huge waves swayed Ocean Tethys, which stretched from the Isthmus of Panama across the Atlantic Ocean, the southern half of Europe, the Mediterranean Sea region, flooding the northern shores of Africa, the Black and Caspian Seas, the territory now occupied by the Pamirs, Tien Shan, the Himalayas, and further through India to the Pacific Islands. Tethys existed for most of the history of the globe (until the Neogene period). Numerous original and unique representatives of the organic world lived in its waters.

The globe at that time had only two huge continents: Laurasia, located on the site of modern North America, Greenland, Europe and Asia, and Gondwana, which united South America, Africa, Hindustan and Australia. These continents were separated by the Tethys Ocean.

Mountain-building processes took place on the continents, erecting mountain ranges in Europe, Asia (Himalayas), and the southern part of North America (Appalachians). The Urals and Altai arose on the territory of our country.

Huge volcanic eruptions filled with lava the plains that were on the site of the modern Alps, Central Germany, England, and Central Asia.

Lava rose from the depths, melted rocks and solidified in huge masses.

The population of the seas is characterized by an abundance of protozoan foraminifera (fusulin ishvagerin). Large bryozoan reefs grew in the shallow zone of the Permian seas. When the seas departed, they left vast shallow lagoons, at the bottom of which salt and gypsum settled, as in our modern Sivashi. Huge areas of lakes covered the continents, just as they currently cover the Karelo-Finnish SSR. The sea basins abounded in stingrays and sharks, among which the outstanding USSR scientist A.P. Karpinsky found a very interesting shark, Helicoprion, which had a dental apparatus in the form of a mud with large teeth. Armored fish give way to ganoid, lungfish.

The climate had clearly defined zones. Glaciations, accompanied by a cold climate, occupied the poles, which were then located differently than in our time. The North Pole was located in the North Pacific Ocean, and the South Pole was near the Cape of Good Hope in South Africa. The desert belt occupied Central Europe; deserts lay between Moscow and Leningrad. Siberia had a temperate climate.

More than half a century ago, a natural history teacher at the local gymnasium, Vokht, lived in Simferopol. On Sundays, he went with a group of his students to the outskirts of the city, mainly up the Salgir River, to collect rocks and minerals.

One day they reached the villages. Maryino and on the right bank of the Salgir they encountered “a block of dark gray dense limestone, which had grown into the ground, like before<сих пор еще не встречали. Глыба лежала отдельно, и других, аналогичных, пород вокруг не было. Находка озадачила Фохта. По аналогии с другими районами, главным образом Донбассом, где имелись такие известняки, Фохт определил их возраст как каменноугольный. Дальнейшие исследования показали, что такие глыбы встречаются и дальше, в направлении на юго-запад, причем, что особенно замечательно, они лежат почти по прямой линии. Самая большая глыба, метров 100 длиной и метров 80 высотой и шириной, лежала в верховьях Марты, притока реки Качи. Более мелкие глыбы были найдены между реками Бодрак и Алма.

In 1916, scientists became interested in the blocks, in particular O. G. Tumanskaya. She then examined the blocks and discovered in them a rich fauna of fossilized foraminiferal rhizomes, cephalopods and gastropods, crustaceans - trilobites, brachiopods and bryozoans. The composition of fossil organisms allowed her to determine the age of these blocks as Permian. Moreover, she established that these limestones were deposited throughout the Permian period, which lasted about 25 million years. She was able to establish that they are very similar to the Permian deposits of the Urals, the Iberian Peninsula, the island of Sicily, the Balkan Peninsula, Asia Minor, the Caucasus, the Pamirs, Indo-China and the southern regions of North America and that they were deposited in shallow sea conditions.

At the same time, all researchers, from Vocht to modern scientists, were surprised that these blocks lie among young Triassic sediments, which formed much later than the Permian period. It was as if they were pulled out of the ground by the hand of some giant and, several million years later, dumped into younger sediments, where they were preserved. How could this happen? This interesting question is solved in different ways.

Some scientists believe that the Permian blocks lie in place, i.e., where the Permian sea was, that in the subsequent Triassic period they emerged from the sea as islands - skerries, as now, for example, ship rocks emerge against Mount Opuk off the southern coast of the Kerch Peninsula, and that Triassic sediments were deposited around them. Others prove that these blocks do not lie in place, that they were brought here by mountain-building processes or rolled down from the southern coast, which ran parallel to the location of the blocks, i.e., had a northeastern strike. Some supporters of this assumption believe that the blocks rolled down from the northern coast of the continent, which was on the site of the modern Black Sea, i.e. from the south, it is given that in Turkey on the Black Sea coast, in the Zanguldak region, coal deposits were found, which show that at that time the land lay to the north. from the coast of Turkey, towards the Crimean Peninsula, this continent remained in Permian times.

We believe that those scientists are right who consider them to be located in the place where they were formed in the Permian time. These were rocky islands (skerries) in the Triassic sea.

The Permian period ends the enormous Paleozoic era of the Earth’s life, which lasted more than three hundred million years, modest traces of which are found in Crimea.

Hello, friends! From time to time I write short notes related to diving, adventures or interesting facts. This time I want to introduce you to two news.

You, of course, know where the name of our portal came from - Tethys. Just in case, let me remind you that in ancient times there was a huge Tethys Ocean, part of which was located on the territory of modern Russia, in the North Caucasus.

The mountains are just over 200 km away from me, and like any restless person, they interest me no less than diving. From time to time, in the mountains, on “untrodden” tourist routes, in river beds or in rock outcrops, my friends and I found traces of the existence of the Tethys Ocean - fossils. In the form of huge spiral shells, the imprint of half an outlandish fish or a fossilized fragment of a coral reef.

The existence of the stone sea of Tethys on the Lago-Naki highland (it is correct to say it is a highland, not a plateau, read the definition in reference literature) has long been written on various tourist sites, as well as on the sites of hotels and recreation centers in the Republic of Adygea and the Absheronsky region of the Krasnodar Territory.

The place is well-known, the road is quite easy, you can get to the cordon by “puzoterka”. But somehow it was not possible to get there. There were a lot of interesting hikes before; on principle, I didn’t want to pay 300 rubles to enter the reserve for some reason, and my colleagues didn’t want to go there either.

At the end of May this year, desires and opportunities came together. We decided to “close the gap” in our mountain hikes. At the same time, prepare for the expedition, about which a little later. No regrets. The game was worth the candle.

Having paid the money and left the car 1 km from the cordon, there is no further passage, we move on foot. Along the way, friends help us carry a transport bag with mountain equipment; we still have a difficult descent into the cave. There is beauty all around - nature is awakening, many Red Book flowers, wonderful panoramas, delicious air. However, the road is difficult, you have to watch your step, rocky slopes give way to snowfields, where it’s easy to fall waist-deep and break a leg. We try to move along the well-worn path.

Our goal is a pass that offers a beautiful view of Oshten, the stone sea of Tethys (as it is called in Adygea) and a memorial obelisk to the soldiers of the border detachment who defended it during the war from the Nazis. The road there is constantly uphill, we make short stops, because each of us has different training and capabilities. After about 6 km we reach the pass, and we are greeted with amazingly beautiful views worthy of our efforts. Everyone takes a lot of photographs and enthusiastically. Next, a small snack. And Olga and I are going to the cave. The cave is a kind of birthday gift from my friends. Well, preparation for the expedition.

A vertical descent of 80 meters, three crossings, a glacier about 35 meters high. But then - unafraid beauty, huge icicles, stalagmites, a dark and gloomy well of water, going into the abyss. Afterwards we had to walk long and patiently up the glacier. But everything worked out, and I was happy. I won’t tell you the location, the cave is not for everyone. Maybe a memorial plaque at the entrance about a climber who died in the 70s will make you think about life and death and the magnitude of the risk. They returned at dusk, happy but tired. The main group waited near the car. We returned home after midnight.

Now about the main point. The entire hike - 13.5 km through snowfields and rocks, descent into a cave and ascent, high mountains - for me was a kind of training and preparation for the August high-mountain underwater search expedition to Karachay-Cherkessia. We don’t want to reveal all the secrets and our plans yet, but the expedition will be unique. We must be the first. Our research will be closely related to the events of the Great Patriotic War. We have a lot of hard work to do. We don't ask for help, but we need it. I am ready to answer all questions through my Facebook profile. Partial support for our project was, unfortunately, provided not by the Krasnodar branch of the Russian Geographical Society, but by the Black Shark diving club, Moscow, for which we are very grateful to them.

P.S.: If you learned a little new about the Tethys Ocean and the Caucasus, then I wrote not in vain.

Always yours,
Ernst Antonov

Photo: E. Antonov, S. Evdokimov, O. Dzhemelinskaya

The expansion of the Atlantic floor in the Late Jurassic and especially in the Early Cretaceous era was accompanied not only by the splits of continental megablocks, but also by their mutual movements. Thus, after the formation of the Central Atlantic Basin, the Gondwana block began to quickly shift eastward relative to Laurasia. Such movements had far-reaching consequences for the Tethys Ocean, the southern edges of which “floated” to the east relative to the northern ones. Then, after the opening of the South Atlantic and the breakup of Gondwana into several continental blocks, the Afro-Arabian block began to press against the northern edges of the Tethys Ocean. It began to slam shut.

During the opening of the Atlantic, the African continent shifted by more than 1,500 km. The speed of its movement in the interval of 180-100 million years was 2-3 cm/year. During this time, it turned 40° relative to Eurasia. In the same direction as the African continent, the Iberian continental block began to migrate, turning slightly to the south. As a result, the Iberian Trough was formed - a deep-sea trough in which turbidites of Early Cretaceous age accumulated. At the same time, the Bay of Biscay opened up on its western extension, and “black” clays—sediments enriched in organic matter—were deposited in its vicinity.

The continental margin of Gondwana, facing the Tethys Ocean, experienced steady subsidence for almost 140 million years, which led to the formation of a powerful lens of Mesozoic and Cenozoic rocks. At the beginning of the Campanian century, the northeastern protrusion of the Afro-Arabian block began to move closer to the opposite screen of Eurasia. This was accompanied by powerful compressions, splits of the continental crust and the subsidence of its marginal blocks. The Tethys bed, which found itself between the continents, was cracked, some of its fragments were literally squeezed out onto the edge of the Nubian shield in the Oman region. Currently, rocks that are completely uncharacteristic of continents rise in the depths of the Oman coast in the form of low mountains. These allochthonous massifs are composed of an ophiolite association, which contains rocks of clearly oceanic origin.

The closure of the eastern branch of Tethys was accompanied by collapses of the young ocean floor, which caused a drop in sea water levels in the Maastrichtian. Surface currents revived, including cold boundary currents, thanks to which in many parts of the outskirts of Africa - from Cameroon, Senegal and Morocco in the Central Atlantic to Algeria, Tunisia and Syria in the Tethys Ocean - there was an intense rise of deep waters. The formation of phosphorites, siliceous rocks and palygorskite-sepiolite clays was associated with it.

The blocking that arose as a result of the convergence of the Afro-Arabian and Eurasian continental blocks in the Oman zone lasted from the Campanian to the Middle Eocene, i.e. 72-48 million years ago. On the northern edges of the Tethys Ocean, the collision led to the drying of many areas previously covered by the sea. In the North Caucasus, in the region of the Dagestan wedge, numerous landslides occurred in Maastricht, which continued into Denmark and the Eocene. Throughout the entire strip of the Tethys Ocean there are traces of shallowing and drying of part of the continental shelves.

In the Eocene, the collapse of the Laurasian continental megablock was completed. Having separated from North America, Eurasia began to move eastward at a speed exceeding the speed of movement of the Afro-Arabian block. This was expressed in shear dislocations and splits of the continental crust, characteristic mainly of Western Europe. However, Tethys was still directly connected with the oceanic depressions of the Atlantic. They were united by a circulation system, and sediments of very similar composition accumulated over vast areas of the continental margins of this region. They were characteristic of vast shallow seas confined to the shelves of Africa and Eurasia. Over many areas of the outskirts, the rise of deep waters, which began in Maastricht (and in some places even in the Turonian), continued, with which in the Ypresian and Lutetian times the spread of palygorskites, sepiolites, cherts and limestones with phosphorites was associated. It is in the Paleocene and Eocene strata of the passive margins that the largest phosphorite deposits are located, which are currently being developed in Mauritania, Western Sahara, Morocco and other regions.

Approximately 48 million years ago, the African continent collided with the Iberian block in a strip of the northern outskirts of Morocco. This led to a slow turn of Africa to the north, as a result of which the western arm of the Tethys Ocean soon slammed shut. A global restructuring of the ocean circulation system has begun. Along the outskirts of the North and South American continents, bottom contour currents rushed to the equator, and from low latitudes the warm waters of the Gulf Stream flowed to the pole. Rocks of the ocean floor were squeezed out onto the outskirts of Morocco and Southern Spain, forming here the Rif mountain range and the Beta Cordillera. This was followed by tectonic activity that affected almost the entire African continent and the Iberian Peninsula. The Pyrenees trough finally slammed shut, and in its place the Pyrenees rose.

From this time begins the complex and largely unrevealed history of Mesogea. The ancient Tethys ocean gradually closed, and in its place the Alpine-Hi-Malayan fold belt grew. Its Himalayan branch arose in the late Miocene, after the Hindustan continental block, which broke away from Gondwana back in the Middle Cretaceous, collided with the southern outskirts of Eurasia. Around the same time, the Arabian Peninsula also moved closer to the edge of this continent, this time in a wide strip from Turkey to the Strait of Hormuz. In the process of convergence of both megablocks, the Tethys oceanic crust was gradually assimilated under its northern margin, disappearing in the Benioff zones. One of them was located in the Zagros mountain range (southwestern regions of Iran). The latter is part of an ancient accretionary ridge that once bordered the active continental margin of Eurasia.

It must be said that in the Mesozoic and Cenozoic the Tethys, apparently, was not very wide, so any restructuring in the system of movement of lithospheric plates led to the collision of the northern and southern continental blocks. At the same time, smaller masses were often torn off from them, subsequently moving on their own. Each collision was accompanied by the crushing of sediments accumulated on the convergent continental margins. The sediments often formed powerful folds that rose from the bottom of the sea in the form of mountainous countries, from which the sea escaped. Such events in geology are defined as folding phases. Each of them is given a name according to the region where it manifested itself most clearly. Thus, the Pyrenean and Alpine folding phases are known. The first belongs to the middle and late Oligocene, the second to the Miocene, when the folded systems of the Alps, Carpathians and Caucasus, part of the single Alpine fold belt, began to form.

It is believed that the Alps, Dinarides and other mountain ranges of Southern Europe arose as a result of the introduction of the Adriatic protrusion of Africa into the Eurasian block. Now this ledge is the bed of the Adriatic and partly Ionian seas. But the rocks that once made up the bottom of the Tethys and Mesogea oceans are now crumpled into folds or collected in a series of covers. They make up the Apennine Peninsula and certain areas of the islands of Corsica and Sardinia. In the collision zone of the African and Eurasian plates, south of the island of Crete and the Peloponnese Peninsula, the East Mediterranean Wall grows - a system of underwater ridges separated by small depressions. Over time, the tops of these ridges will rise above sea level and ultimately turn into a large folded mountain belt, similar in structure to the Alpine. Since the uplift of a mountainous country is accompanied by subsidence of the crust in the adjacent parts of the platforms and middle massifs, this process has already led to the subsidence of individual blocks of Africa. The Levantine depression that arose here is a forward trough, where a fairly thick cover of continental, including salt-bearing, and marine sediments has already formed. Similar troughs in the Late Cenozoic existed on the edge of the European Platform, at the junction with the growing mountain systems of the Caucasus, Carpathians, and Alps.

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▲ 2.6–2.7 billion years ago, the entire Earth was covered by the waters of a huge ocean. There were no continents, and the land consisted of archipelagos of islands scattered among the endless water surface. The earth's crust, which was not yet strong, was in constant motion. Volcanic forces created new islands and archipelagos and gradually expanded the land mass. In that ancient era, the only living things on earth may have been bacteria or microbes, the remains of which were found in layers formed two billion years ago.
▲ Approximately 1.8–2 billion years ago, in the warm water of shallow sea bays, the first simple algae that lived in water appeared - unicellular and multicellular (sponges, brachiopods, mollusks, crustaceans), that is, representatives of all types of invertebrate animals. Later, in the Proterozoic era, bacteria and algae became widespread, and invertebrate animals appeared at the end of the era. Then, in fact, on Earth there was a division of living nature into two branches - plant and animal, and they each began to develop in their own way.
▲ Even 200 million years ago, the entire landmass of the Earth existed in the form of a single supercontinent of Pangea, washed by the waves of the all-terrestrial ocean Panthalassa. Several million years passed, and Pangea turned out to be divided by a latitudinal reef into two parts: northern - Laurasia, which included modern Asia (without India), Europe and North America, and southern - Gondwana, which included Africa, India, Australia, South America and Antarctica. About 135 million years ago, Africa began to separate from South America. Another 50 million years passed - and North America and Europe diverged.
▲ In the Paleozoic era, when the origin of life on Earth began, then in the Mesozoic and Cenozoic, on the territory of present-day Karachay-Cherkessia, the waters of the ancient huge bay splashed Ocean Tethys(Thetis). Tethys is a system of ancient sea basins (named after the ancient Greek goddess of the sea Thetis - Thejcida, or Tetis, the daughter of King Neptune - the god of the seas). ▲ For a long time, a number of scientists have suggested that the Mediterranean, Black and Caspian seas are relics of Tethys. Sedimentary rocks were marine and were often found in areas stretching from the Pyrenees to the Himalayas and China. But was Tethys just a chain of shallow seas or a real ocean? This remained controversial. What spoke in favor of the oceanic past of Tethys? In some areas of the deep-sea bed of the Mediterranean, Black and Caspian seas, as it turned out, a transitional type of the earth’s crust still exists, a seemingly preserved junction between the shelf continuation of the European continent and the bottom of the ancient ocean. An even more convincing argument were the finds in Cyprus. There, at the base of Mount Trudos, geologists discovered hypermafic rocks, that is, igneous ultrabasic rocks, poor in silicic acid and enriched in magnesium. At one time, this became a real sensation: previously, such rocks were taken by dredges from the gorges of mid-ocean ridges located at great depths, from gorges where the constant birth of new earth's crust occurs. Therefore, the mined blocks were considered samples of the material that makes up the base of the ocean floor (and, according to some scientists, even the upper mantle of our planet).
In 1978, an employee of the Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry of the USSR Academy of Sciences V. Yarmolyuk discovered hyperbasites in the center of the Asian continental massif - in the Gobi Desert (Southern Mongolia). This was direct proof that Tethys was indeed an ocean!
▲ More than 500 million years ago, that is, until the very beginning of the Tertiary period of the Cenozoic era, and this time is 60–65 million years distant from us, the vast Tethys Ocean, stretching through southern Europe and Central Asia, was connected to the Atlantic Ocean in the west, and in the east - with the Quiet. The ocean was characterized by low salinity and abounded in foraminifera - the simplest microscopic organisms from the order of rhizomes. The layers that have accumulated over 30 million years in the ocean are called foraminifera.
▲ In the Caucasus Mountains at a considerable altitude, scientists find stones left to us as a legacy by the Tethys Ocean with imprints of the bones of sea animals and algae. The remnants of the ocean are the Kura-Arakchinskaya lowland and the Kuma-Manych depression with numerous salt lakes, the steppe “sea” Manych and Sengileevskoe lake, the Batalpashinsky salt lakes.
▲ Soil salinity is one of the “legacies” of the Tethys Ocean. Farmers have to wage a constant struggle against this phenomenon, which requires considerable resources.
▲ By the middle of the Tertiary period (about 30 million years ago), as a result of the uplift and subsidence of the earth's crust, Tethys was separated first from the Pacific Ocean, and then from the Atlantic. On the site of the present Caucasus, the so-called Maykop Sea was formed, which was replaced by other deep-sea basins - Chokrak and Karagan. They deposited layers of clays, marls, limestones, and sandstones.
▲ The fact that the waves of Tethys splashed over the territory of present-day Karachay-Cherkessia is evidenced not only by numerous exhibits of the republican museum-reserve - various fossils, but also by the highest peaks, which are composed of marine sediments. They contain remains of Jurassic sea shells that are over 130 million years old. Moreover, in many places the ancient rocks, which were marine sediments and lavas of underwater volcanic eruptions, were then changed under the influence of high temperatures and enormous pressure. Over time, they turned into crystalline schists, gneisses and granites.
▲ Scientists have found that the waves of the ocean either retreated or again covered the current territory of Karachay-Cherkessia. Marine deposits of almost all geological periods are found here: Cambrian, Silurian, Devonian, Carboniferous, Permian, Triassic (geologists divide the last 600 million years of Earth's history into eras, and eras into periods).
▲ In the Paleozoic, land formed on the site of the present Sea of Azov. By the middle of the Mesozoic era, the waves of the ancient sea, inhabited by ammonites, belemnites, corals and sponges, splashed here again. In the Cenozoic era, the Sarmatian Sea splashed on the site of the North Caucasus, which was successively replaced by the Meotic Sea and the Pontic desalinated basin. In the process of partial shallowing and drainage of the Pontic basin in the Tertiary period, the Cimmerian lake-sea was formed, with a characteristic estuary-delta regime. At the end of the Tertiary period, the Cimmerian and Akchagyl sea basins successively replaced each other, the waves of which extended to the east and northeast up to the present foothills of the Urals and the Kama and Belaya basins.
Through the depression of modern Lake Manych, the brackish Akchagyl basin was connected with the desalinated Chaudinsky, which turned into the Ancient Euxinsky and formed a single whole with the Baku (later Khazar) brackish basin. The waters of the Aral-Sarykamysh plain (depression) also rushed here. During the Quaternary period, in place of the present North Caucasus, the Azov and Black Seas, the waters of seven more seas were replaced. Note : The classification and periodicity of the emergence of ancient seas is given according to the works of the largest Russian zoologist and hydrobiologist, Academician S. A. Zernov.
▲ About 150 million years ago, when the Mediterranean, Black, Azov, Aral and Caspian seas had not yet been born in today’s contours, a slow rise of the bottom of the Tethys Ocean began, which was facilitated by volcanic transformations. The greatest geological catastrophe took place on Earth - the Indian continent collided with the Asian continent in its movement. It was then that the masses of Tibet and the Himalayas appeared on the globe. Forces of incredible power shook the Earth, in many places tore and reared its hard shell. As a result, new land areas and “young” mountainous countries appeared - the Alps, Andes and the Caucasus, stretching for 1.4 thousand kilometers. Volcanic forces not only helped the mountainous part of the Caucasus rise from the ocean floor, but also thoroughly “worked” on its relief.
▲ In the Neogene, 25 million years ago, the territory of the North Caucasus was covered by the Chokrak Sea. In the area of the village of Belomechetskaya, which is located 20 kilometers north of Cherkessk, where the Kuban cuts the sandy sediments of this ancient sea, in 1926, accumulations of bones of very ancient mammals were found.
▲ About 15 million years ago, the connection between the two parts of the Tethys Gulf was interrupted. Instead of the eastern part (on the site of the present North Caucasus), the desalinated Sarmatian Sea was formed, and its inhabitants partially died out and partially adapted to the desalinated water. The Sarmatian Sea stretched from present-day Vienna to the foot of the Tien Shan and included the modern Black, Azov, Caspian and Aral seas. Isolated from the ocean, it was greatly desalinated by the waters of the rivers flowing into it, but for a very long time such typical ocean animals as whales, sirens and seals lived in it. Later they were gone.
About 12–13 million years ago the sea retreated north. The Caucasian island turned into a large peninsula of Asia Minor. Later, this place was occupied by the Central Sarmatian Sea, which disappeared about five million years ago. Mollusks from this sea are still found in the limestones of the outskirts of Rostov-on-Don and in the famous catacombs near Odessa.
The sea that later surrounded the ancient Stavropol Peninsula (now the Stavropol Upland) was called the Upper Sarmatian; it was similar to the previous one, but differed in a different composition of mollusks.
▲ The chronicle of the Earth is under man's feet. Its sheets are the layers of rocks that make up the earth's crust. Where they lie flat, only the top pages, most recently written, are visible. Where they have bends and breaks, deeper “sheets” recorded thousands and millions of years ago are exposed.
For residents of the North Caucasus, it is enough to drive from the northern border of the Stavropol Territory to the southern border of Karachay-Cherkessia, that is, to the Main Caucasus (Watershed) Range, in order to see almost the entire series of rock strata over the entire 3 billion years of earth’s history at a distance of 200–300 kilometers. Therefore, these places are a genuine geological museum.
In areas of the deep sea, at its bottom, clays were usually deposited, but if the sea was shallow, then the deposited layers consisted of sand or even pebbles, which is clearly visible in the territory of Cherkessk. In drying bays in dry climates, various salts or layers of gypsum could accumulate. Where the sea often flooded the coast with lush tropical vegetation, forests died at its bottom, the wood of which over time turned into coal with layers of sand and clay sediments, as, for example, this happened in the territory of the present Karachay region in the Jurassic period of the Mesozoic era.
▲ If you take limestone from the Pastbishchny Ridge in the vicinity of Ust-Dzheguta, you can see that it consists of petrified corals. Corals live in the seas, which means there was once a sea here. Corals can only develop in warm water, therefore, the sea during this period in the Ust-Dzheguta area was warm, with an average annual water temperature of at least 20 ° C, that is, it was a tropical sea. Corals always live near the coast, at depths of no more than 90 meters, from here we see that the sea in this place was shallow. Now there is no sea here. Coral limestone lies thousands of meters above sea level. Consequently, the region of Ust-Dzheguta, and also Cherkessk (since it is also located half a kilometer above sea level), underwent mountain building, and the former seabed became the surface of the Pastbishchny Ridge.
▲ During the Miocene (3–7 million years ago), significant mountain-building movements occurred. As a result, Tethys shrinks in size and is divided into a series of brackish basins.
▲ At the end of the Miocene and the beginning of the Pliocene (2–3 million years ago), the Sarmatian basin shrank to the size of the Meotic Sea. At this time, a connection with the ocean reappeared, the water became saltier, and marine species of animals and plants penetrated here.
▲ In the Pliocene (1.5–2 million years ago), communication with the ocean again completely ceased, and in place of the salty Meotic Sea, the almost fresh Pontic Sea-lake arose. In it, the future Black and Caspian seas communicate with each other in the place where the North Caucasus is now located.
In the Pontic Sea, marine fauna disappeared, but a brackish-water fauna formed. Its representatives are still preserved in the Caspian and Azov Seas, in the desalinated areas of the Black Sea.
▲ Further uplift of the land a million years ago finally divided the Black and Caspian seas. The Caspian Sea remains desalinated.
▲ With the onset of the Quaternary or Ice Age, the salinity and composition of the inhabitants in the future Black Sea continue to change, and its outline also changes. At the end of the Pliocene (less than one million years ago), the Pontic lake-sea decreased in size to the boundaries of the Chaudin lake-sea.
▲ As a result of the melting of ice at the end of the Mindel glaciation (about 400–500 thousand years ago), the Chaudin Sea is filled with meltwater and turns into the Ancient Euxinian basin. In outline it resembles the modern Black and Azov Seas.
▲ During the post-glacial period, which began about 200 thousand years ago, the Azov-Black Sea basin, as well as the Aral and Caspian seas, were finally formed
▲ On the site of the Ancient Euxinian basin, the Karangat Sea was formed 100–150 thousand years ago. At this place, 18–20 thousand years ago, there was already the Novoevksinsky sea-lake. About 10 thousand years ago, instead of a sea-lake, the modern Black Sea was formed, and 8 thousand years ago its connection with the Mediterranean Sea was formed. Then the salinization of the Black Sea gradually began.
▲ The coastline of the modern Sea of Azov took its current shape no more than 10 thousand years ago, when the last glaciers of the East European Plain disappeared.
▲ After a sudden earthquake 8 thousand years ago, the Bosporus Strait was formed. A mass of salty Mediterranean water then poured into the Black Sea basin. Historians believe that this event happened before the eyes of the people who lived here and could be reflected in the legend of the Great Flood (after all, the Bible does not indicate exactly the place where the flood took place).

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