The appearance of man is associated with the moment of making primitive but conscious tools. Modern science determines the age of human existence to be no less than 2 million years. This period in the history of the Earth is called anthropogenic. It corresponds to the last period of the geological history of the Earth, the so-called Quaternary system, when the relief, climate, vegetation and animal world took on a modern look. The Quaternary system is divided into Pleistocene and Holocene (2 million-10 thousand years ago, last 10 thousand years, respectively). The Quaternary period is characterized by a general cooling of the Earth's climate and the development of extensive continental glaciations in the Pleistocene. Modern paleoclimatology quite accurately determines the temperature regime of the Earth and its climatic characteristics, determined by many factors of a cosmic and terrestrial nature /6/. Study of the temperature regime of the last 2 million years in various regions of the northern hemisphere by various groups of researchers different countries and different methods led to almost identical results and made it possible to derive a climate curve divided into periods of cold weather, glaciation and warming. The set of these periods is combined into a stratigraphic scale, which has its own name in different parts of the Northern Hemisphere - Alpine, Northern European, Eastern European, Siberian /7/, North American /8/. The paleotemperature of the Southern Hemisphere, the values ​​of which for the last 400 thousand years were experimentally obtained by drilling the Antarctic cover /9/, correlates with the established values ​​of the paleotemperature of the Northern Hemisphere. Enlarge Map of glaciations in Europe over the last 300 thousand years Glaciations in the Pleistocene have been studied quite well, especially the last three (Map of glaciations): Dnieper glaciation (250-190 thousand years ago) - the maximum area of ​​cover ice in Europe. On the northern European stratigraphic scale it is called the Drenthe stage of the Saal glaciation. Moscow glaciation (150-120 thousand years ago), called the Warth stage on the North European stratigraphic scale. Valdai glaciation, or Vistula glaciation on the North European stratigraphic scale, (60-10 thousand years ago). All three glaciations covered Scandinavia, the north of the West European Plain, the Baltic, and the west and north of the Russian Plain with the Scandinavian ice sheet. Between glaciations there were warm interglacials: the Likhvinsky one before the Dnieper glaciation after the Oksky one; Odintsovo between the Dnieper and Moscow glaciations; The Mikulino interglacial on the East European stratigraphic scale (Riess-Wurm on the Alpine, Eemian on the North European, Kazantsevsky on the Siberian), between the Moscow and Valdai glaciations, lasted in the period 120-60 thousand years ago. The last warming occurred about 13 thousand years ago. Increase

Graph 1 shows global temperature variations over the last 500 thousand years in Eastern Europe. A sinusoidal cyclicity of the temperature regime with a main period of approximately 100-120 thousand years is clearly visible. With this cyclicity, global glaciations of the Northern Hemisphere and warm interglacials were repeated.

Graph 1 shows global temperature variations over the last 500 thousand years in Eastern Europe. A sinusoidal cyclicity of the temperature regime with a main period of approximately 100-120 thousand years is clearly visible. With this cyclicity, global glaciations of the Northern Hemisphere and warm interglacials were repeated. Periods of warming and glaciation were accompanied by post-glacial transgressions and glacial regressions (decrease in level due to the concentration and conservation of water in cover glaciation) of the World Ocean and especially inland seas. Fluctuations in the level of the Black Sea-Caspian basin, in which the main role was played by the temperature regime of northern Eurasia, have been studied since the early Pleistocene. During the Oka glaciation, this basin experienced regression, and during the Likhvin interglacial, transgression (ancient euxine in the Black Sea and lower Khazar in the Caspian). At the same time, the connection of the Black and Mediterranean seas occurred. The Dnieper glaciation caused the Neo-Euxinian regression, which significantly reduced the surface of the Black Sea and dried up the Manych Caspian-Black Sea Strait and the Sea of ​​Azov (see Glaciation Map). During the Odintsovo interglacial, the Caspian reconnected with the Black Sea, during the Moscow glaciation it was disconnected, during the Mikulino interglacial it was connected, and during the Valdai glaciation it was disconnected. The question of connection and separation of these seas also depended on tectonic movements. Superimposed on the main temperature cycle were smaller harmonics, including those associated with the precession of the earth's axis and indicated by Tilak. It didn't change general pattern global cycle, but changed, and sometimes significantly, the temperature regimes of individual millennia. To consider the question of the possibility of human habitation in the polar latitudes during the interglacial period according to paleoclimatic conditions, let us turn to the nearest Mikulin interglacial in the period 120-60 thousand years ago. In the period 110-75 thousand years ago, the average temperature of the Northern Hemisphere exceeded modern temperatures by up to 10 degrees C. During this period, in the polar latitudes the climate was subtropical and especially favorable for the development of flora and fauna and human habitation. Increase

Graph 2 shows the updated temperature curve of Eastern Europe over the last 100 thousand years on a thousand-year scale. A similar process occurred throughout northern Eurasia. In addition to smaller harmonics, a “dip” in the maximum cold in positive side in the middle of the Valdai glaciation.

Graph 2 shows the updated temperature curve of Eastern Europe over the last 100 thousand years on a thousand-year scale. A similar process occurred throughout northern Eurasia. In addition to smaller harmonics, a “dip” of the cold maximum in a positive direction is visible in the middle of the Valdai glaciation. Within Eastern Europe, some authors divide this glaciation into two independent ones - the Kalinin and Ostashkovo, separated by a long mega-interstadial (48-22 thousand years ago), called in some works the Mologo-Sheksna interglacial. The graph shows that during this period in Europe it was colder than at present, but comparatively low temperatures did not induce the glaciation process. The Valdai glaciation, and especially its last Ostashkov phase, caused a decrease in the level of the Black Sea to 80 m from the modern level. Thus, the Mikulin interglacial is the closest interglacial in which, according to climatic parameters, humans could live in the North Pole region. Increase

13.5 thousand years ago, rapid warming began, accompanied by significant climatic fluctuations of the period 13.5-9 thousand years ago. Thus, over the period of 9.7-9 thousand years ago, the average temperature in northwestern Europe increased by 15 degrees. C and has reached the modern level.

Let's turn to the Holocene. 13.5 thousand years ago, rapid warming began, accompanied by significant climatic fluctuations of the period 13.5-9 thousand years ago. Thus, over the period of 9.7-9 thousand years ago, the average temperature in northwestern Europe increased by 15 degrees. C and has reached the modern level (Graph 3). This led to intensive melting of the glaciers of the Ostashkovo glaciation, floods and the formation of the modern water system of northern Europe, the Baltic, the White Sea, the Black Sea and the Russian Plain, except for the rivers of the western Urals, where there were no glaciations. The Baltic glacial lake, whose level was above ocean level, after the breakthrough of the bridge in central Sweden 10,200 years ago, connected with the ocean, about 9,200 years ago it was isolated from the ocean due to the glacioisostatic uplift of Scandinavia, about 7,200 years ago it again connected with the world ocean as a result of transgression and tectonic movements and took modern shape. The Black Sea entered its modern boundaries, rising by 70-80 m after its “drying out” during the last glacial period. The Upper and Middle Volga water basin was finally formed. This process began after the era of maximum Dnieper glaciation. The Volga stream, which previously flowed along the Don channel, rushed almost at a right angle into the Kama, the channel of which from the junction of the Northern Uvals and the Ural ridge to the Caspian Sea has existed for millions of years. The depth of the paleo-Kama channel reached hundreds of meters, the width was up to 3.5 km. After the retreat of the ice of the Valdai glaciation, human settlement of these territories began. Graph 3 shows a detailed curve of the temperature regime of Eastern Europe over the last 10 thousand years (Holocene). A steady increase in temperature in the period 10-8 thousand years ago led to the establishment of a temperature maximum, when average temperatures in the Northern Hemisphere exceeded modern ones by 1.5-2.0 degrees C, and in Eastern Europe by 2-2.5 degrees. This period, called the Atlantic, lasted until 5-4.5 thousand years ago. The level of the world's oceans and associated inland seas has risen by several meters compared to today. Coastal levels of that time with marks up to 6 m were recorded on all coasts. In Russia, these are the Baltic Sea, the Black Sea region, the coasts of the Arctic and Pacific oceans, and islands not subject to tectonic shifts. The level of the Caspian Sea, no longer connected to the Black Sea due to the tectonic uplift of the Manych depression, increased by 8-9 m relative to the present day. The Caspian Sea was also fed by thawed Central Asian glaciers from the Karakum River. large river Uzboy /10/. The warming of the Atlantic period led to the melting of almost all ice sheets. Climatic changes led to a restructuring of vegetation cover and directly affected the development of the animal world. The zone of broad-leaved and coniferous forests on the Eurasian continent has spread almost everywhere to the Arctic coast, including Yakutia and Chukotka. In the last 5-thousand-year period and up to our time, relative cooling occurred (subboreal periods), followed by minor warmings that did not reach the warming of the Atlantic period. During these periods there was a latitudinal shift in the habitat various types and representatives of flora and fauna. In light of the above, a favorable climate for humans in the polar latitudes during the interglacial period was in the period 110-75 thousand years ago. In the Atlantic period of the Holocene (8-5 thousand years ago), on the lands closest to the Pole (Franz Josef Land in the Eurasian sector of the Arctic), the glacier of the Ostashkov phase of the Valdai glaciation was preserved. The more southern Arctic islands were thawed and habitable, but no continent existed in the Arctic during the Holocene. The Lomonosov and Mendeleev ridges went under water 15-20 thousand years ago, but 100 thousand years ago the Arctic continent existed, as many researchers believed and still believe, for example, the famous oceanographer Ya.Ya.Gakkel. Therefore, from paleogeography it follows that the “interglacial civilization” of the Rus, following from Vedic sources and placed by Tilak in the period of the Young-Sheksna mega-interstadial, should most likely be pushed back to the Mikulino interglacial, or considered as post-glacial and existing on the southern Arctic islands in the Atlantic period Holocene.

The territory of modern Russia in Quaternary times was repeatedly subjected to large-scale glaciations, separated by interglacial eras, the climate of which was close to the modern one or even warmer. Within the glacial epochs, stages were distinguished, alternating with warmings of a lower rank - interstadials. The age of the oldest ice age is about 800 thousand years. The largest glacial stage was associated with the development of the Don glaciation, which began more than 500 thousand years ago. The ice then advanced into the basins of the Oka, Don and Lower Volga up to 51° N. w. The later glaciation - Oka (more than 350 thousand years ago) was smaller and, apparently, did not extend beyond the Oka basin.

In Siberia, the maximum glaciation of the early Pleistocene was characterized by two major advances. The ice moved south to 62–64° N. sh., into the basins of the modern lower reaches of the Irtysh, the middle reaches of the Ob and Yenisei to the mouth of the Podkamennaya Tunguska; in the northeast they reached the eastern coast of the Taimyr Peninsula.

In the Middle Pleistocene, which began about 350 thousand years ago, two glacial stages are distinguished. The early one was characterized by the development of ice cover mainly in the northeast of the European part of Russia. Its boundaries are not precisely established. The younger Dnieper ice sheet developed already in the second half of the Middle Pleistocene, about 250 thousand years ago. The ice then advanced to the middle reaches of the Dnieper and the upper reaches of the Oka, mainly from the western, Scandinavian, center. The role of the Dnieper ice sheet especially increased during the second, Moscow stage of the same glaciation. Its relief-forming activity was clearly manifested in the appearance of the Smolensk-Roslavl, Tver, Klin-Dmitrov, Galich-Chukhloma uplands.

On the territory of Siberia at this time, two large sheet glaciations were known, reaching 59–60° N in Western Siberia. w. The first extensive two-phase Samara glaciation developed at approximately the same time as the Dnieper glaciation. Ice advanced onto the mainland from the shelf and penetrated south into the basins of the modern Ob and Yenisei rivers to the mouth of the Podkamennaya Tunguska. Second, the Taz glaciation is comparable in age to the Moscow stage of the Dnieper.

In the Late Pleistocene, the ice advances that followed the last, Mikulino (Kazantsev) interglacial, which ended 110–115 thousand years ago, have been studied in more detail. It is believed that the first, early Valdai ice advance was modest in size in the European part of Russia, and the ice did not extend beyond the Baltic Basin at that time. On the contrary, due to climatic reasons, glaciation of this age could have been more extensive in the Siberian region of Russia. The maximum of the last cover glaciation of the late Pleistocene - Valdai (Sartan) dates back to 20-18 thousand years ago. Then to the territory European Russia The Scandinavian glacier advanced to the modern upper reaches of the Dnieper and Volga. In the final stages of its existence, it, like all previous ice sheets, left vast expanses of hilly-ridge relief formed by boulder loams and sands (moraine). Within the mountainous areas in the Late Pleistocene, individual glacial domes and caps formed, and in some areas, for example in Verkhoyansk, semi-cover and reticulate glaciation.

In the Asian part of Russia, in the vast lowlands and plains of Western, Central and Eastern Siberia and in Eastern Europe, a permafrost region spread south of the boundaries of the Scandinavian glacier. The first reliable traces of continuous permafrost with signs of polygonal ice wedges in Northeast Asia are known from the late Pliocene, in the rest of Siberia - from the Eopleistocene and early Pleistocene, on the East European Plain - from the Middle Pleistocene (Pechora cold stage).

In the last 250 thousand years, a clear tendency has been recorded for a reduction in the area of ​​cover glaciation during the cold stages of the Quaternary period and an increase in the area of ​​continuous permafrost (permafrost zone - underground glaciation). Maximum sizes The cryolithozone reached the end of the Late Pleistocene (Late Valdai - Sartan cold stage). At this time, the southern border of permafrost in Russia moved south of 50° N. w. Polygonal ice wedges formed everywhere here. Their thawing led to the widespread development of relict cryogenic microrelief.

During the second half of the Quaternary period (the last million years), a radical restructuring of natural zones took place within natural cycles. During the optimum period of the last (Mikulino) interglacial (about 125 thousand years ago), the forest belt expanded significantly in the north and south due to the reduction, respectively, of the tundra zone, which remained only on the Arctic islands, the north and in the northern sections of the Gydan Sea, isolated as a result of the ingression of the Kazantsev Sea. peninsula and Taimyr, as well as the steppe zone.

The zone of broad-leaved forests has expanded enormously, replacing the entire subzone of coniferous-broad-leaved forests and a significant part of the southern taiga subzone. The border of the broad-leaved forest zone in the European part of Russia ran more than 500 km to the north and 200–300 km to the south of its current position. Accordingly, forest-steppes, steppes and semi-deserts shifted significantly to the south.

In high latitudes, within , the tundra gave way to forest-tundra, the landscapes of which began to approach the ocean coast. From the south, the forest-tundra subzone was adjacent to the taiga region, represented by larch forests.

South of the northern taiga subzone in Central Siberia There was an area of ​​cedar-pine forests, which to the east, in Central Yakutia, were replaced by pine-birch and birch-larch (on the right bank of the Lena) forests.

Landscape zoning underwent a radical restructuring during the Ice Age and especially during the phase of greatest cooling, which corresponded to the maximum in the development of glacial systems of the Valdai-Sartan age, that is, about 20–18 thousand years ago. The plant communities of the periglacial region had no modern analogues.

The forest belt has completely degraded. Taiga and broad-leaved forests ceased to exist as components of the zonal structure. Representatives of woody vegetation retained only a subordinate importance in landscape systems. Within the entire extratropical space, specific open-type landscapes, the core of which were steppe and tundra communities adapted to cold periglacial conditions, occupied a dominant position.

I would be grateful if you share this article on social networks:

“Pleistocene” is what the famous English geologist Charles Lyell called the era immediately preceding ours in 1839. Translated from Greek, this word means “youngest era.” For in its deposits, fossil invertebrates do not differ from modern ones. “He could not have given a more successful name, even if he had known other signs. For many, the Pleistocene means glaciation. And this is justified, because the most outstanding event of that era was repeated glaciation, and glaciers occupied an area three times larger than the area of ​​​​their modern distribution, writes R. Flint in the monograph “Glaciers and Pleistocene Paleogeography.” - But glaciation was only one of the consequences of climate changes that occurred over millions of years before the Pleistocene. Climate changes caused: fluctuations in air and sea water temperatures within several degrees, movement of zones with a certain amount of precipitation, fluctuations in the snow line about an average height of 750 m, rise and fall of sea level by at least 100 m, deposition of loess-like soil by winds over a vast area material, freezing and thawing of soil in high latitudes, changes in the regime of lakes and rivers, migration of plant communities, animals and prehistoric humans.”

The idea that glaciers were once much more widespread than now has long occurred to observant inhabitants of mountain valleys and slopes. For in the meadows, arable lands and forests they found traces of former glaciers - polished boulders, polished and furrowed rocks, ridges of moraines. These traces were especially clearly visible in the Alps. It is not surprising that it was in Switzerland that the idea was born that there were once much more glaciers on the globe than there are now, and they covered vast areas.

Not all scientists agreed with this. Throughout almost the entire 19th century, there was heated debate about the great glaciation of our planet. And as they went, more and more evidence spoke in favor of the point of view that the great glaciation really happened, although even today there are risky hypotheses according to which all the evidence in favor of this glaciation can be interpreted differently and, therefore, , it exists only in the works of scientists.

Traces of past glaciations have been found in various parts of the planet. Geologists quickly learned to distinguish one from another glaciation that occurred more than two million years ago, traces of which were found north of Lake Huron in North America; glaciation that took place 600–650 million years ago, traces of which were found in the north and east of the Urals; glaciation, called Gondwana, which covered the continents of the Southern Hemisphere, as well as Hindustan and the Arabian Peninsula before the onset of the “era of lizards” - the Mesozoic; and, finally, the last great glaciation, which spread its ice over many areas of the Northern Hemisphere and “froze” Antarctica, before former mainland, where tropical fauna flourished and lizards and amphibians lived.

Map of the maximum extent of Pleistocene glaciation.

We are only interested in the last glaciation, at the end of which modern fauna and flora were formed and at the end of which homo sapiens - man appeared modern type. After long (and to this day not completely completed) discussions, scientists have learned to distinguish traces of the last stage of this glaciation from traces of earlier stages. In Western Europe it is called Würm, in North America - Wisconsin. It also corresponds to traces of the glaciation called Zyryansk, found in Northern Asia, as well as the Valdai glaciation, traces of which were found on the territory of Russia.

IN Lately Geologists, glaciologists, oceanologists and other representatives of various Earth sciences who have to deal with these traces have learned to identify within the last stage - the last glaciation! - several stages. It turned out that the Würm-Wisconsin-Zyryansk-Valdai glaciation was divided into a number of separate glaciations, between which there were periods of warming, glaciers decreased in size, the ocean level rose accordingly, and the waters of the next post-glacial flood advanced onto the land.

The last stage of the last glaciation of the planet began about 70 thousand years ago. But 30 thousand years ago, the level of the World Ocean, as the latest research shows, was approximately equal to the modern one. It is obvious that at that time the climate was not glacial, but much warmer. Following this, a new cold snap began. More and more ice was added to the monstrous mass of Antarctica's glaciers. Greenland continued to expand its ice shell, and there was much more ice than now. A huge ice sheet covered the territory of North America. Glaciers covered areas of Western Europe, including British Isles, the Netherlands, Belgium, northern Germany and France, Scandinavian countries, Finland, Denmark, the Alps. In Eastern Europe, they were in the center of Russia, reached Ukraine and the Don, covered the Northern and Central Urals, Taimyr and other areas of Siberia. Huge glaciers descended from the mountains of Chukotka, Kamchatka, Central Asia. Glaciers lay in the mountains of Australia, New Zealand, and Chile.

How were these glaciers formed? Naturally, due to water. And this water was supplied by the ocean. Therefore, its level decreased as the volume of glaciers increased. Areas of the shelf that were under water were drained and became parts of continents and islands, and underwater mountains turned into new islands. The outlines of the land at that time were significantly different from modern ones. In place of the Baltic and North Seas there was land, although covered with a shell of ice. A vast land stretching from north to south for one and a half thousand kilometers, called Beringia, connected Asia and America with a bridge along which animals could migrate, and after them primitive hunters, the first Columbuses of the New World. The Australian mainland was united with the island of Tasmania in the south, and in the north it formed a single landmass with New Guinea. A single massif connected with Indochina and the Malacca Peninsula was formed by Java, Kalimantan, Sumatra and many small islands of Indonesia. Was dry land Northern part Sea of ​​Okhotsk, land bridges connected with the Asian continent of Sri Lanka, Taiwan, Japan, Sakhalin. The land was on the site of the present Bahamas, as well as large expanses of shelf that stretched in a wide strip along the eastern coast of the North; Central and South America.

These were the contours of the continents during the maximum of the last stage of the Würm (also known as Wisconsin, Zyryansk, Valdai) glaciation 20–25 thousand years ago. And they began to change, flooded with the waters of the global flood, which began 16-18 thousand years ago.

Ice, water and shelf

Where was the border between sea and land before the last global flood? It would seem that it is not difficult to determine it if we remember that the shelf is the submerged outskirts of the continents. The level of the World Ocean at that time was lower than today. Exactly how many meters, apparently, can be judged by the shelf. However, in different seas and oceans the shelf boundaries are at different depths.

The shelf boundary of the California coast is at a depth of 80 meters, the Gulf of Mexico - 110, the coast of Argentina - 125, and off the Atlantic coast of the USA and Nigeria - at a depth of 140 meters. Sections of the Northern shelf Arctic Ocean submerged to depths of several hundred meters, and the Sea of ​​Okhotsk - over a kilometer. How can we determine what the level of the World Ocean was? After all, it couldn’t be a kilometer lower than it is now in the Sea of ​​Okhotsk, in the Atlantic - 140 meters, and off the Pacific coast of California - only 80 meters!

Blocks earth's crust can fail not only on land, but also under water (especially since the shelf crust is continental). Apparently, it is precisely these tectonic failures that explain the enormous depths of the shelf of the Sea of ​​Okhotsk and the deep-water areas of the Arctic Ocean. However, the earth's crust can not only fall, but also rise. Therefore, it is impossible to take shallow shelf depths, for example, 80 meters off the California coast, as a standard, and explain all others that exceed them by subsidence of the crust.

So by what depth mark should we determine the level of the World Ocean when we strive to outline the boundaries of the former land, which has now become a shelf after the last global flood - 80, 100, 120, 140, 180, 200, 1000 meters? Discard maximum and minimum values? But even without them, the spread is quite large.

Apparently, data from another science - glaciology, the science of ice - should be called upon for help. Based on the area and thickness of the glaciers that covered the planet during the last glaciation, it is not difficult to calculate how many meters the level of the World Ocean should have dropped. It is not so easy to determine the area, much less the thickness, of the ice that covered the Earth two dozen millennia ago.

Map of the successive stages of retreat of the last European ice sheet.

Modern ice covers an area of ​​about 16 million square kilometers, with more than 12 million in Antarctica. To calculate the volume of ice, you also need to know the thickness of the ice cover. It was possible to establish it only thanks to the research of geophysicists. In Antarctica, the thickness of the ice sheets reaches 3000–4600 meters, in Greenland - 2500–3000 meters. The average height of the ice sheet in Antarctica is 2300 meters; in Greenland its value is much less. On the planet today, continental ice contains 27 million cubic kilometers of ice, which, if melted, will raise the sea level, as already mentioned, by 66 meters (more precisely, by 66.3 meters). One should also take into account floating sea ice, the area of ​​which, depending on the season and average annual temperature, ranges from 6.5 to 16.7 million square kilometers in the Northern Hemisphere and from 12 to 25.5 million square kilometers in the Southern Hemisphere. According to V. M. Kotlyakov’s assessment in the book “Snow Cover of the Earth and Glaciers,” sea ice and snow currently cover 25 percent of the area in the Northern Hemisphere and 14 percent in the Southern Hemisphere, amounting to a total of 100 million square kilometers.

These are the data about the modern period. How much ice was there on the continents and in the sea during the last glaciation? Different researchers estimate their volume differently. Indeed, when making this assessment, it is necessary to take into account both the boundaries of the distribution of continental ice (and they are determined very conditionally) and the thickness of the ice cover (here the estimates are even more conditional: try to accurately determine the thickness of the ice that melted thousands of years ago!). But glaciers could also cover the areas of the current sunken lands, the shelf and be in the form of motionless “dead” ice, leaving no traces by which glaciologists determine the boundaries of ancient glaciation. This is why estimates of the volume and area of ​​ice of the last great glaciation vary so much: for example, the area is estimated at about 40, 50, 60 and 65 million square kilometers. The total volume of this ice is also estimated differently. As a result, an oceanographer who believes that the level of the World Ocean during the last glaciation was 90 meters lower than today chooses a lower estimate of the volume of water contained in the ice, and believes that glaciological data confirm his point of view. The oceanographer, who believes that the sea level in that era was lower not by 90, but by 180 meters, proceeds from other estimates given by glaciologists, and also believes that his conclusions are consistent with the data of glaciology. And, conversely, glaciologists, citing oceanologists, believe that their assessments are confirmed by data from oceanologists studying the shelf.

However, despite all the disagreements, most modern scientists believe that the level of the World Ocean in the last ice age was lower than the current one by more than 100 meters and less than 200 meters. Researchers who adhere to the golden mean believe that the level of the World Ocean at that time was lower than today by an amount of about 130–135 meters, equal to the average depth of the shelf (when we're talking about about the “depth of the shelf,” we, of course, mean the depths of its edge, the edge from which the cliff to the depths of the ocean begins; Naturally, the closer to the shore, the shallower the depth of the shelf spaces will be).

Ice melting rate

Even if we accept the minimum estimate of the level of the World Ocean before the last global flood, it still suggests that this flood must have been enormous. The spaces of ancient land, which were at that time below the level of 100 meters, should have been flooded. But this land was inhabited not only by animals, but also by people. For primitive man, such an invasion of water would have been a real disaster if... If the colossal supply of ice accumulated by glaciers had melted quickly. But can they a short time turn into the water of a global flood of ice, the thickness of which reaches tens, hundreds, thousands of meters? Of course no! Not only “in one disastrous night,” but also in a year, a decade, a hundred years, enormous deposits of ice, several kilometers thick, cannot melt.

This means that the global flood, which began 16–18 thousand years ago and raised the level of the World Ocean to the modern level, occurred slowly, gradually and stretched over hundreds and thousands of years? Facts obtained by a variety of sciences - from glaciology to archeology - indicate that this, most likely, was exactly the case. However, the process of melting ice at the same time did not proceed as evenly and smoothly as it seemed until recently.

Firstly, because in the thousands of years that have passed since the end of the last glaciation, there has been no continuous warming of the climate. The gradual melting of the ice stopped as soon as a temporary cooling occurred. The ocean has stabilized at a certain level - that is why terraces are found underwater, left by surf waves not only at depths of about 100–140 meters (the level before the ice begins to melt), but also at depths of 50, 40, 30, 20, 10 meters. For example, after carefully studying the bottom of the Bering Sea, the American geologist D. M. Hopkins came to the conclusion that its coastline during the last glaciation lay at a depth of about 90–100 meters. In addition, at the bottom there are coastlines at depths of 38, 30, 20–24 and 10–12 meters. They reflect “stops” in the melting of ice and the rise in sea levels.

But the melting of ice was not the only thing that stopped. The destruction of glaciers proceeded at a much faster pace than their formation. Moscow glaciologist G. N. Nazarov devoted a special chapter to the mechanism of destruction of the Great Glaciation in his interesting book “Glaciations and Geological Development of the Earth”.

“Many geologists categorically deny the possibility of earthquakes and tectonic movements under the influence of changing external loads from water or ice, mistakenly considering this effect for the earth’s crust to be insignificant. However, in this regard, even the volumes of water accumulated during the creation of artificial reservoirs can be dangerous. For example, on the Colorado River, the accumulation of 40 billion tons of water caused subsidence of the earth's crust and tremors. A devastating earthquake occurred in January 1966 in Evrytania (Greece) due to the formation of an artificial reservoir 150 m deep. An increase in seismicity after the filling of reservoirs was noted on the Volga. Significant earthquakes, as noted by J. Rothe, occur when reservoirs are filled if the water column exceeds 100 m. In the areas of eight high-rise dams, he noted the occurrence of earthquakes with a magnitude of up to 5.1–6.3, writes G. N. Nazarov. - It is believed that the most strong earthquake in New Madrid, numbering over 1200 impacts in flat platform (!) conditions in 1874, as a result of which an area of ​​500 km 2 was lowered and flooded with water, occurred as a result of the accumulation of sedimentary material in the Mississippi River valley.”

How much stronger must have been the movements of the earth's crust during the melting of the ice of the last great glaciation, if masses of water were moving, the weight of which was tens of times greater than the weight of the Caucasus mountain range! At the same time, it must also be taken into account that the land, freed from the monstrous weight of the glaciers, began to rise, and its growth rate was rapid. For even today, territories that were freed from glaciers several thousand years ago are “growing” upward at a speed that is significant even on a large scale. human life.

Back in the 17th century, Finnish bishop Erik Sorolainen, taking measurements on rocks, noticed with amazement that the “firmament of the earth,” which was motionless according to the dogmas of the Bible, was slowly but surely rising. The marks he made in the water ended up on land several years later. In the 18th century, the Swede Carl Linnaeus, the author of the first classification of all living creatures on the planet that has not lost its significance to this day, and his compatriot Anders Celsius, the inventor of the thermometer of the same name, after carrying out careful measurements, discovered that the shores of Northern Sweden were rising, and those of Southern Sweden were falling.

Modern science explains the rise of the coasts of Northern Sweden and Finland by the fact that the earth’s crust here continues to “straighten”, although the load of glaciers of the last glaciation was dropped thousands of years ago. In the north of the Gulf of Bothnia, the rise is occurring at a rate of 1 meter per century. Scotland rose almost 50 meters, freed from glaciers, and Spitsbergen rose almost 100 meters. Of course, in the past the rise was even faster than it is now. For example, the rate of rise of Scandinavia, freed from the load of glaciers, reached 4.5 centimeters per year - 45 meters per century!

“The results of studies of geological deposits formed over the last 10 thousand years show that there is a certain connection between the stages of glaciation, manifestations of seismicity and the intensity of landslide formation. It is possible that the beginning of the sliding of glacial blocks into the sea was initiated by one of the episodic earthquakes of internal or glacioisostatic origin. Earthquakes can also contribute to sudden breakthroughs of subglacial waters and warm currents into high-latitude areas. It is possible that as a result of this, some volumes of glacial accumulations were destroyed and dumped into the sea in very short periods of time, giving an abrupt nature to the process of destruction of ice sheets. This nature of destruction is confirmed, in our opinion, by existing geographical, paleographic and historical data,” writes G. N. Nazarov. And he further gives an example of such a “leap” that was possible during the era of the glacial “flood”.

On the Schmidt Plain in Antarctica there is a depression, the bottom of which lies one and a half kilometers below ocean level, and the surface of the ice filling it is three kilometers above ocean level. If the ice sheet contained in this depression were to collapse, it would cause sea levels to rise by two to three meters!

Thus, the advance of waters could not be smooth, but sometimes be catastrophic. The post-glacial flood could have its peaks and peaks; it could be accompanied by earthquakes and tsunamis, rapid invasion of meltwater, landslides and rubble in the mountains, such as those that caused local floods. In a word, the global flood, despite the fact that it lasted for many millennia, could give rise to natural disasters similar to those that formed the basis of the myths and legends about the flood of various peoples of the Earth.

Chronicle of the last global flood

Naturally, these flood peaks are not so easy to detect. In our time, we can record its “stops” - along ancient coastlines that are now under water. For example, in relation to the Bering Sea and its terraces, D. M. Hopkins outlines the following sequence: a terrace at a depth of 90–100 meters marks the ocean level before the flood, it refers to the coastline that existed 17–20 thousand years ago. The coastline at a depth of 38 meters was flooded approximately 13 thousand years ago, and the coastline at a depth of 30 meters was flooded approximately 11,800 years ago. The coastline, now sank to a depth of 20–24 meters, became submerged about 9–10 thousand years ago. The time of flooding of the ancient shores at a depth of 12 and 10 meters has not yet been established.

How can this time be established? First of all, based on sediments found at one or another depth. The radiocarbon dating method makes it possible to fairly accurately determine the age of organic sediments - and, therefore, the time when the current shelf was dry land. Thus, at the bottom of Norton Bay, which washes the shores of Alaska, peat accumulated 10 thousand years ago. From this it follows that there was once dry land here. The peat was found at a depth of 20 meters - and Hopkins believes that the coastline at a depth of 20 meters "may have been flooded soon after" - that is, about 10 thousand years ago. Since organic sediments could not be found at depths of 12 and 10 meters, it is impossible to establish with a sufficient degree of accuracy the age of flooding of the ancient shores that now lie at these depths.

Data of this kind were obtained not only for the Bering Sea, but also for a number of other sea basins that were dry land during the last glaciation. The shell of a mollusk living at depths of no more than four meters was raised from a depth of 130 meters off the Atlantic coast of the United States. Its age is about 15 thousand years. This means that at that time there was shallow water in this area and the sea level over the elapsed time has risen by more than 120 meters. On the same coast, peat that was 11 thousand years old was raised from a depth of 59 meters. Shells of shallow-water mollusks dating back 7,000, 8,000 and 9,000 years were recovered from depths of 20 to 60 meters. Finally, from various depths, up to 90 meters, 45 teeth belonging to mastodons and mammoths were recovered from the shelf in the same area. Their age was even less - 6000 years.

It is not so easy to find organic remains at the bottom of the sea. Indeed, during the time that elapsed after the onset of the flood, sea sediments superimposed on the “land” sediments. Therefore, nowadays, bottom drilling is widely used in order to break through the thickness of marine sediments and reach sediments formed in land conditions. Having drilled through a layer of marine sediments, at a depth of 21 meters off the coast of Australia, they found layers of peat that formed about 10 thousand years ago. At a depth of 27 meters at the bottom of the Strait of Malacca, layers of peat of the same age were discovered. Peat 8,500 years old was discovered off the coast of Guyana at a depth of 21 meters.

The scatter of data is obvious: peatlands of different ages were found at the same depth and, conversely, peatlands of the same age were found at different depths - 21 and 27 meters. Therefore, we cannot say with certainty whether the level of the World Ocean was 21 or 27 meters lower than it is today. But it is equally obvious that the search for dating is within one or two millennia, and the search for ocean levels is within ten meters. And these scales are incomparable with the scale of tens, hundreds of thousands, or even millions of years and with the depth range of the order of several kilometers, which the “flood hunters” operated at first.

How they restore the history of the last glacial - and global! - Flood scientists of our days? Let's try to give a brief chronicle of the flood, into which, without a doubt, corrections and additions will be made, but which, apparently, still corresponds in its main features to the real picture.

25 000 years ago - the maximum glaciation of the last stage of the last ice age of the Pleistocene. The level of the World Ocean is more than 100 meters below the current level (but does not exceed 200 meters).

Between the 20th and 17th millennium- the beginning of melting ice and rising sea levels. The rate of increase is about 1 centimeter per year.

15 000 years ago - the ocean level was approximately 80 meters lower than today.

10 000 years ago - the ocean level was 20–30 meters lower than today.

6000 years ago - a sharp slowdown in the glacial flood, the formation of the modern coastline. The ocean level is 5–6 meters lower than the modern one or equal to the modern one.

When did the flood stop?

As glaciers disappeared and the level of the World Ocean rose, land bridges that connected islands and continents found themselves under water. About 12–16 thousand years ago, Cook Strait separated the North Island of New Zealand from the South Island. One and a half thousand years later, Australia was separated by the Bass Strait from Tasmania and the Torres Strait from New Guinea. After another two thousand years, Sakhalin separated from the mainland. Around the same time, the Bering Strait was formed, and the land connection between the Old and New Worlds, which had existed for many tens of thousands of years, was interrupted.

Over the past six to seven thousand years, the contours of sea and land have been formed in the area of ​​the Bahamas, the Gulf of Mexico, the North Sea, the Baltic and the seas washing the islands of Indonesia, most of which at that time were still connected to each other and to the Malacca Peninsula. This is evidenced by numerous finds of peat bogs, bones of land animals, Stone Age tools and even primitive human settlements at the bottom of today’s seas and straits.

In the Baltic, peat about 7,500 years old was raised from a depth of 35 and 37 meters. A 9,300-year-old peat bog was raised from a depth of 39 meters from the bottom of the English Channel. Off the Shetland Islands, at a depth of 8–9 meters, deposits of peat bogs were found that formed 7000–7500 years ago. The list of such finds could be continued, but it is already obvious that the North Sea, the Baltic, and the seas of Indonesia are amazingly young from a geological point of view. They are a product of the last global flood.

It is very possible that 5000–6000 years ago the level of the World Ocean was not only equal to the current level, but also several meters (but no more than six!) higher than it. In other words, the maximum level of the glacial flood occurred at the time when the most ancient civilizations of our planet were born - in the Nile Delta and the Tigris-Euphrates valley.

Traces of this peak of the flood, called the Flanders transgression, were found not only in the Belgian province of Flanders, but also on the shores of the Mediterranean Sea and other seas, on the coast of Australia and the Black Sea region.

Some researchers, for example G.N. Nazarov, whom we quoted, suggest that the Flemish flood could have occurred as a result of the destruction of part of the glacial masses. This destruction, as you know, can be accompanied by earthquakes, a rapid rise of the earth’s crust freed from the weight of glaciers, tsunamis and other phenomena that can give rise not to the usual “slow” flood caused by the melting of ice, but to a rapid flood, which is of a planetary, worldwide nature .

Perhaps this is precisely what is reflected in the myths and traditions of some peoples. Indeed, at that time, 5000–6000 years ago, people were no longer nomadic tribes of gatherers and hunters, as they were during the era of the last great glaciation, but settled peoples, creating writing, creating temples and palaces. Was the peak of the flood reflected in the Dravidian legends about the southern ancestral home, in the ancient Indian legend about the prophet Manu, in the ancient Greek myth of Deucalion's flood and, finally, in the Sumerian-Babylonian version of the story about the flood, which was reflected in the Bible?

Of course, this is just a hypothesis, or many scientists consider the very fact of the Flanders transgression to be unproven, not to mention its catastrophic nature). But be that as it may, this is the only version of the global flood that can be reflected in the mythology and legends of antiquity. All other real world floods, including the last glacial one, as you yourself have seen, have nothing to do with ancient legends and myths.

Cities under water

The pace of the global flood, caused by the melting of the great glacier, slowed sharply about 6,000 years ago... Why then do we find flooded or half-submerged cities, ports, ancient piers and piers everywhere?

At the bottom of the Dnieper-Bug estuary lie ancient city walls and buildings Lower City famous ancient Olbia. The defensive towers of another ancient city, Chersonesos, are located at the bottom of Quarantine Bay. At the bottom of Sukhumi Bay, as many researchers suggest, are hidden the ruins of one of the most ancient ancient cities of the Black Sea region - Dioscuria. Near the modern port of Feodosia, under water there is a pier built in the era of antiquity. The walls of the capital of the Asian Bosporus - Phanagoria - go to the bottom of the Kerch Strait. Bulgarian submarine archaeologists discovered at the bottom of the Black Sea coast of their homeland traces of sunken settlements from antiquity, as well as the remains of ancient Apollonia, founded almost three thousand years ago.

Even more impressive is the list of ancient cities, ports and settlements found in the Mediterranean, completely or partially submerged. Salamis on the island of Cyprus. Harbors of the Phoenician ports and city-states of Tire and Sidon. The flooded port of Caesarea, the capital of the Kingdom of Judah. The breakwaters of the ancient Greek port of the glorious city of Corinth, which went to a depth of three meters. Protective walls of the ancient cities of Gythion and Kalydon on the coast of Greece. Flooded ancient tombs on the island of Melos in the Aegean Sea. Sunken defensive walls 200 meters from the shore of the island of Aegina. Buildings of the famous ancient resort of Bahia, sank to a depth of 10 meters to the bottom Gulf of Naples. The flooded piers of Ostia, the harbor of great Rome. Etruscan settlements at the bottom of the Tyrrhenian Sea. Port buildings of the ancient cities of Taufira and Ptolemais near the coast of Libya. The port and coastal buildings of Cyrene, the famous Greek colony in Africa. The sunken city of the island of Djerba lying off the coast of Tunisia. Numerous cities and settlements at the bottom of the Adriatic Sea.

This list is far from complete. Underwater archaeologists expect to find many other cities swallowed up by the waters of the Mediterranean Sea and its associated seas. But similar cities under water exist not only in the warm Mediterranean and Black Sea region, but also in the harsh North Sea - cities built not in the era of antiquity, but much later, in the Middle Ages, and flooded or half-flooded during the last millennium. At the bottom of the Baltic Sea lie settlements and sites of Stone Age people, and there also lie the ruins of one of the largest ports of medieval Europe, the city of Yumna, created by the coastal Slavs.

Water swallowed up not only medieval cities, but also cities created in modern times, several centuries ago. Remember Port Royal, nicknamed “pirate Babylon”. A third of the buildings in Orangetown, a smuggling village on the island of St. Eustatius, are located at a depth of 7 to 20 meters. The ruins of the “sugar port” of Jamestown on the island of Nevis lie at a depth of 3 to 10 meters.

Finally, the flood threatens and modern cities. The medieval city of Metamauco sank to the bottom of the Gulf of Venice about a thousand years ago. Its inhabitants founded a new city, which became the pearl of the Adriatic - Venice. "Venice is sinking!" - the call is being made to the whole world, for the palaces, churches, buildings of this beautiful city of the Doges, following Metamauco, are inevitably plunging under water. The medieval buildings and temples of the Brazilian city of Olinde on the east coast of the Atlantic have partially sunk and continue to sink. And our beautiful city of Leningrad is constantly threatened by floods.

Does this mean the global flood has not stopped?

The decline and death of many cities are explained by other reasons. Port Royal, as you know, went under water after the earthquake. The Adriatic coast is sinking, and therefore the cities standing on its low-lying shores are gradually drowning. Terrible storms caused the death of many cities on the North Sea coast. And yet, the main reason that many coastal cities are under water is that the level of the World Ocean is steadily rising.

Now the ocean is rising at a negligible rate. What does 1 millimeter per year, 10 centimeters per decade, 1 meter per century mean? But where is the guarantee that this rate of global flood will not increase? After all, we have studied in detail only a very small period of time covering the course of the last glacial flood, and even then there are many gaps in our knowledge of its rhythm. The history of the Earth says that the planet experienced much more powerful glaciations than the last. And where is the guarantee that they will not happen again - or, conversely, that the rapid melting of the remaining ice will not cause a catastrophe on the scale of all humanity, and not individual regions and cities? Moreover, more and more often voices are heard about man-made heating of the atmosphere, unknown in previous times.

Are we facing a global flood? This will be discussed in the final chapter of the book.

Before this, scientists had been predicting an imminent attack on Earth for decades. global warming, due to human industrial activity and they assured that “there will be no winter.” Today, it seems, the situation has changed dramatically. Some scientists believe that a new ice age is beginning on Earth.

This sensational theory belongs to an oceanologist from Japan, Mototake Nakamura. According to him, starting from 2015, cooling will begin on Earth. His point of view is also supported by a Russian scientist - Khababullo Abdusammatov from Pulkovo Observatory. Let us recall that the last decade was the warmest for the entire period of meteorological observations, i.e. since 1850.

Scientists believe that already in 2015 there will be a decrease solar activity, which will lead to climate change and cooling. Ocean temperatures will decrease, ice will increase, and overall temperatures will drop significantly.

The cooling will reach its maximum in 2055. From this moment on, a new ice age will begin, which will last 2 centuries. Scientists have not specified how severe the icing will be.

There is a positive aspect to all this; polar bears no longer seem to be in danger of extinction)

Let's try to figure it all out.

1 Ice Ages can last hundreds of millions of years. The climate at this time is colder, continental glaciers form.

For example:

Paleozoic Ice Age - 460-230 million years ago
Cenozoic Ice Age - 65 million years ago - present.

It turns out that in the period between: 230 million years ago and 65 million years ago, it was much warmer than now, and We live today in the Cenozoic Ice Age. Well, we've sorted out the eras.

2 Temperature during the Ice Age is not uniform, but also changes. Within the Ice Age, ice ages can be distinguished.

glacial period(from Wikipedia) - a periodically repeating stage in the geological history of the Earth lasting several million years, during which, against the background of a general relative climate cooling, repeated sharp growths of continental ice sheets occur - ice ages. These epochs, in turn, alternate with relative warmings - epochs of reduced glaciation (interglacials).

Those. we get a nesting doll, and within the cold ice age, there are even colder periods when the glacier covers the continents on top - ice ages.

We live in the Quaternary Ice Age. But thank God during the interglacial period.

Last ice age(Vistula glaciation) began ca. 110 thousand years ago and ended around 9700-9600 BC. e. And this is not so long ago! 26-20 thousand years ago the volume of ice was maximum. Therefore, in principle, there will definitely be another glaciation, the only question is when exactly.

Map of the Earth 18 thousand years ago. As you can see, the glacier covered Scandinavia, Great Britain and Canada. Note also the fact that the ocean level has dropped, and many parts of the earth's surface that are now under water have risen from the water.

The same map, only for Russia.

Perhaps the scientists are right, and we will be able to observe with our own eyes how new lands emerge from under the water, and the glacier takes over the northern territories.

If you think about it, the weather has been pretty stormy lately. Snow fell in Egypt, Libya, Syria and Israel for the first time in 120 years. There was snow even in tropical Vietnam. In the United States for the first time in 100 years, temperatures dropped to a record -50 degrees Celsius. And all this against the backdrop of above-zero temperatures in Moscow.

The main thing is to be well prepared for the Ice Age. Buy a plot of land in the southern latitudes, away from big cities (there are always a lot of hungry people there during natural disasters). Do it there underground bunker with food supplies for years, buy weapons for self-defense and prepare for life in the style of Survival Horror))

One of the curves showing sea level fluctuations over the past 18,000 years (the so-called eustatic curve). In the 12th millennium BC. sea ​​level was about 65 m lower than today, and in the 8th millennium BC. - already at less than 40 m. The rise in level occurred quickly, but unevenly. (According to N. Morner, 1969)

The sharp drop in sea level was associated with the widespread development of continental glaciation, when huge masses of water were withdrawn from the ocean and concentrated in the form of ice in the high latitudes of the planet. From here, glaciers slowly spread towards the middle latitudes in the northern hemisphere on land, in the southern hemisphere - along the sea in the form of ice fields that overlapped the shelf of Antarctica.

It is known that in the Pleistocene, the duration of which is estimated at 1 million years, three phases of glaciation are distinguished, called in Europe Mindel, Ries and Würm. Each of them lasted from 40-50 thousand to 100-200 thousand years. They were separated by interglacial eras, when the climate on Earth became noticeably warmer, approaching the modern one. In some episodes it became even 2-3° warmer, which led to the rapid melting of ice and the release of vast areas on land and in the ocean. Such dramatic climate changes were accompanied by equally dramatic fluctuations in sea level. During the era of maximum glaciation, it decreased, as already mentioned, by 90-110 m, and during interglacial periods it increased to +10... 4-20 m compared to the current one.

Pleistocene - no single period, during which significant fluctuations in sea level occurred. Essentially, they mark almost all geological epochs in the history of the Earth. Sea level has been one of the most unstable geological factors. Moreover, this has been known for quite a long time. After all, ideas about transgressions and regressions of the sea were developed back in the 19th century. And how could it be otherwise, if in many sections of sedimentary rocks on platforms and in mountainous folded areas, clearly continental sediments are replaced by marine ones and vice versa. Sea transgression was judged by the appearance of remains of marine organisms in the rocks, and regression was judged by their disappearance or the appearance of coals, salts or red flowers. By studying the composition of faunal and floristic complexes, they determined (and are still determining) where the sea came from. The abundance of thermophilic forms indicated the invasion of waters from low latitudes, the predominance of boreal organisms indicated transgression from high latitudes.

In the history of each specific region, its own series of transgressions and regressions of the sea stood out, since it was believed that they were caused by local tectonic events: invasion sea ​​waters associated with the subsidence of the earth's crust, their departure - with its uplift. When applied to the platform areas of the continents, on this basis a theory of oscillatory movements was even created: cratons either sank or rose in accordance with some mysterious internal mechanism. Moreover, each craton obeyed its own rhythm of oscillatory movements.

It gradually became clear that transgressions and regressions in many cases occurred almost simultaneously in different geological regions of the Earth. However, inaccuracies in paleontological dating of certain groups of layers did not allow scientists to come to a conclusion about the global nature of most of these phenomena. This conclusion, unexpected for many geologists, was made by American geophysicists P. Weil, R. Mitchum and S. Thompson, who studied seismic sections of the sedimentary cover within the continental margins. Comparison of sections from different regions, often very distant from one another, helped to reveal the confinement of many unconformities, breaks, accumulation or erosional forms to several time ranges in the Mesozoic and Cenozoic. According to these researchers, they reflected the global nature of ocean level fluctuations. The curve of such changes, constructed by P. Weil et al., makes it possible not only to identify epochs of high or low standing, but also to estimate, of course to a first approximation, their scale. As a matter of fact, this curve summarizes the work experience of geologists of many generations. Indeed, you can learn about the Late Jurassic and Late Cretaceous transgressions of the sea or its retreat at the Jurassic-Cretaceous boundary, in the Oligocene and Late Miocene, from any textbook on historical geology. What was new, perhaps, was that these phenomena were now associated with changes in the level of ocean waters.

The scale of these changes was surprising. Thus, the most significant marine transgression, which flooded most of the continents in Cenomanian and Turonian times, is believed to have been caused by a rise in the level of ocean waters by more than 200-300 m above the modern one. The most significant regression that occurred in the Middle Oligocene is associated with a drop in this level by 150-180 m below the modern one. Thus, the total amplitude of such fluctuations in the Mesozoic and Cenozoic was almost 400-500 m! What caused such enormous fluctuations? They cannot be attributed to glaciations, since during the late Mesozoic and the first half of the Cenozoic the climate on our planet was exceptionally warm. However, many researchers still associate the mid-Oligocene minimum with the onset of a sharp cooling in high latitudes and with the development of the glacial shell of Antarctica. However, this alone was probably not enough to reduce the sea level by 150 m at once.

The reason for such changes was tectonic restructuring, which entailed a global redistribution of water masses in the ocean. Now we can only offer more or less plausible versions to explain fluctuations in its level in the Mesozoic and Early Cenozoic. Thus, analyzing the most important tectonic events that occurred at the turn of the Middle and Late Jurassic; as well as the Early and Late Cretaceous (which are associated with a long rise in water levels), we find that it was these intervals that were marked by the opening of large oceanic depressions. The Late Jurassic saw the emergence and rapid expansion of the western arm of the ocean, the Tethys (the region of the Gulf of Mexico and the Central Atlantic), and the end of the Early Cretaceous and most of the Late Cretaceous eras were marked by the opening of the southern Atlantic and many trenches of the Indian Ocean.

How could the formation and spreading of the bottom in young ocean basins affect the position of the water level in the ocean? The fact is that the depth of the bottom in them at the first stages of development is very insignificant, no more than 1.5-2 thousand m. The expansion of their area occurs due to a corresponding reduction in the area of ​​ancient oceanic reservoirs, which are characterized by a depth of 5-6 thousand. m, and in the Benioff zone, areas of the bed of deep-sea abyssal basins are absorbed. The water displaced from disappearing ancient basins raises the overall ocean level, which is recorded in land sections of the continents as sea transgression.

Thus, the breakup of continental megablocks should be accompanied by a gradual rise in sea level. This is exactly what happened in the Mesozoic, during which the level rose by 200-300 m, and perhaps more, although this rise was interrupted by eras of short-term regressions.

Over time, the bottom of young oceans became deeper and deeper as the new crust cooled and its area increased (the Slater-Sorokhtin law). Therefore, their subsequent opening had much less influence on the position of the ocean water level. However, it would inevitably lead to a reduction in the area of ​​the ancient oceans and even to the complete disappearance of some of them from the face of the Earth. In geology, this phenomenon is called the “collapsing” of the oceans. It is realized in the process of the rapprochement of continents and their subsequent collision. It would seem that the slamming of ocean basins should cause a new rise in water levels. In fact, the opposite happens. The point here is a powerful tectonic activation that covers converging continents. Mountain-building processes in the zone of their collision are accompanied by a general uplift of the surface. In the marginal parts of the continents, tectonic activation manifests itself in the collapse of blocks of the shelf and slope and their lowering to the level of the continental foot. Apparently, these subsidences also cover adjacent areas of the ocean floor, as a result of which it becomes much deeper. General level ocean waters are falling.

Since tectonic activation is a one-act event and covers a short period of time, the drop in level occurs much faster than its increase during spreading of young oceanic crust. This is precisely what can explain the fact that sea transgressions on the continent develop relatively slowly, while regressions usually occur abruptly.

Map of possible flooding of Eurasian territory at various values ​​of the probable rise in sea level. The scale of the disaster (with the sea level expected to rise by 1 m during the 21st century) will be much less noticeable on the map and will have almost no impact on the lives of most states. The areas of the coasts of the North and Baltic Seas and southern China are enlarged. (The map can be enlarged!)

Now let's look at the issue of AVERAGE SEA LEVEL.

Surveyors leveling on land determine the height above “mean sea level.” Oceanographers who study sea level fluctuations compare them with elevations on the shore. But, alas, even the “long-term average” sea level is far from a constant value and, moreover, is not the same everywhere, and the sea coasts rise in some places and fall in others.

An example of modern land subsidence is the coasts of Denmark and Holland. In 1696, in the Danish city of Agger, there was a church 650 m from the shore. In 1858, the remains of this church were finally swallowed up by the sea. During this time, the sea advanced on land at a horizontal speed of 4.5 m per year. Now on the western coast of Denmark, the construction of a dam is being completed, which should block the further advance of the sea.

The low-lying coasts of Holland are exposed to the same danger. The heroic pages of the history of the Dutch people are not only the struggle for liberation from Spanish rule, but also an equally heroic struggle against the advancing sea. Strictly speaking, here the sea does not advance so much as the sinking land recedes before it. This can be seen at least from the fact that average level high waters on the island. The Nordstrand in the North Sea rose by 1.8 m from 1362 to 1962. The first benchmark (altitude mark above sea level) was made in Holland on a large, specially installed stone in 1682. From the 17th to the mid-20th century, The soil subsidence on the Dutch coast occurred at an average rate of 0.47 cm per year. Now the Dutch are not only defending the country from the advance of the sea, but also reclaiming the land from the sea by building grandiose dams.

There are, however, places where the land rises above the sea. The so-called Fenno-Scandinavian shield, after being freed from the heavy ice of the Ice Age, continues to rise in our time. The coast of the Scandinavian Peninsula in the Gulf of Bothnia is rising at a rate of 1.2 cm per year.

Alternating lowering and rising of coastal land is also known. For example, the shores of the Mediterranean Sea sank and rose in places by several meters even in historical times. This is evidenced by the columns of the Temple of Serapis near Naples; marine elasmobranch mollusks (Pholas) have made passages in them to the height of human height. This means that from the time the temple was built in the 1st century. n. e. the land sank so much that part of the columns was immersed in the sea and, probably, for a long time, since otherwise the mollusks would not have had time to do so much work. Later, the temple with its columns again emerged from the waves of the sea. According to 120 observation stations, over 60 years the level of the entire Mediterranean Sea has risen by 9 cm.

Climbers say: “We stormed a peak so many meters above sea level.” Not only surveyors and climbers, but also people completely unrelated to such measurements are accustomed to the concept of height above sea level. It seems to them unshakable. But, alas, this is far from the case. Ocean levels are constantly changing. It is fluctuated by tides caused by astronomical reasons, wind waves excited by the wind, and changeable like the wind itself, wind surges and water surges off the coast, changes in atmospheric pressure, the deflecting force of the Earth's rotation, and finally, the heating and cooling of ocean water. In addition, according to the research of Soviet scientists I.V. Maksimov, N.R. Smirnov and G.G. Khizanashvili, the ocean level changes due to episodic changes in the speed of rotation of the Earth and movement of its axis of rotation.

If you heat only the top 100 m of ocean water by 10°, the sea level will rise by 1 cm. Heating the entire thickness of ocean water by 1° raises its level by 60 cm. Thus, due to summer warming and winter cooling, sea level in the middle and high latitudes subject to noticeable seasonal fluctuations. According to the observations of the Japanese scientist Miyazaki, the average sea level at west bank Japan rises in summer and falls in winter and spring. The amplitude of its annual fluctuations is from 20 to 40 cm. Level Atlantic Ocean in the northern hemisphere it begins to rise in the summer and reaches a maximum in winter; in the southern hemisphere, its reverse trend is observed.

The Soviet oceanographer A. I. Duvanin distinguished two types of fluctuations in the level of the World Ocean: zonal, as a result of the transfer of warm waters from the equator to the poles, and monsoon, as a result of prolonged surges excited by monsoon winds that blow from the sea to land in the summer and in in the opposite direction in winter.

A noticeable slope of sea level is observed in areas covered by ocean currents. It is formed both in the direction of the flow and across it. The transverse slope at a distance of 100-200 miles reaches 10-15 cm and changes with changes in current speed. The reason for the transverse inclination of the flow surface is the deflecting force of the Earth's rotation.

The sea also noticeably reacts to changes in atmospheric pressure. In such cases, it acts as an “inverted barometer”: more pressure- lower sea level, lower pressure - higher sea level. One millimeter of barometric pressure (more precisely, one millibar) corresponds to one centimeter of sea level height.

Changes in atmospheric pressure can be short-term and seasonal. According to the research of the Finnish oceanologist E. Lisitsyna and the American one J. Patullo, level fluctuations caused by changes in atmospheric pressure are isostatic in nature. This means that the total pressure of air and water on the bottom in a given section of the sea tends to remain constant. Heated and rarefied air causes the level to rise, cold and dense air causes the level to fall.

It happens that surveyors conduct leveling along the seashore or overland from one sea to another. Having arrived at the final destination, they discover a discrepancy and begin to look for the error. But in vain they rack their brains - there may not be a mistake. The reason for the discrepancy is that the level surface of the sea is far from equipotential. For example, under the influence of prevailing winds between the central part Baltic Sea and the Gulf of Bothnia, the average difference in level, according to E. Lisitsyna, is about 30 cm. Between the northern and southern part The level of the Gulf of Bothnia at a distance of 65 km changes by 9.5 cm. Between the sides of the English Channel the difference in level is 8 cm (Kriz and Cartwright). The slope of the sea surface from the English Channel to the Baltic, according to Bowden’s calculations, is 35 cm. Level Pacific Ocean and the Caribbean Sea at the ends of the Panama Canal, whose length is only 80 km, differs by 18 cm. In general, the level of the Pacific Ocean is always slightly higher than the level of the Atlantic. Even if you move along the Atlantic coast of North America from south to north, a gradual rise in level of 35 cm is found.

Without dwelling on the significant fluctuations in the level of the World Ocean that occurred in past geological periods, we will only note that the gradual rise in sea level, which was observed throughout the 20th century, averages 1.2 mm per year. It is apparently caused by the general warming of the climate of our planet and the gradual release of significant masses of water that had been bound by glaciers until that time.

So, neither oceanographers can rely on the marks of surveyors on land, nor surveyors on the readings of tide gauges installed off the coast at sea. The level surface of the ocean is far from an ideal equipotential surface. Its exact definition can be achieved through the joint efforts of geodesists and oceanologists, and even then not before at least a century of simultaneous observations of vertical movements of the earth’s crust and sea level fluctuations at hundreds, even thousands of points have been accumulated. In the meantime, there is no “average level” of the ocean! Or, what is the same thing, there are many of them - each point has its own shore!

Philosophers and geographers of hoary antiquity, who had to use only speculative methods for solving geophysical problems, were also very interested in the problem of ocean level, although in a different aspect. We find the most specific statements on this matter in Pliny the Elder, who, by the way, shortly before his death while observing the eruption of Vesuvius, wrote rather arrogantly: “There is nothing in the ocean at present that we cannot explain.” So, if we discard the disputes of Latinists about the correctness of the translation of some of Pliny’s arguments about the ocean, we can say that he considered it from two points of view - the ocean on flat earth and the ocean on a spherical Earth. If the Earth is round, Pliny reasoned, then why don’t the waters of the ocean on its reverse side flow into the void; and if it is flat, then for what reason? ocean waters They don’t flood the land if everyone standing on the shore can clearly see the mountain-like bulge of the ocean, behind which ships are hidden on the horizon. In both cases he explained it this way; water always tends to the center of the land, which is located somewhere below its surface.

The problem of sea level seemed insoluble two thousand years ago and, as we see, remains unresolved to this day. However, the possibility cannot be ruled out that the features of the level surface of the ocean will be determined in the near future by geophysical measurements made using artificial Earth satellites.

Gravity map of the Earth compiled by the GOCE satellite.
These days …

Oceanologists re-examined the already known data on sea level rise over the past 125 years and came to an unexpected conclusion - if throughout almost the entire 20th century it rose noticeably slower than we previously thought, then in the last 25 years it has grown at a very rapid pace, says the paper. article published in the journal Nature.

A group of researchers came to these conclusions after analyzing data on fluctuations in the levels of the Earth's seas and oceans during high and low tides, which are collected in different corners planets using special tide gauge instruments for a century. Data from these instruments, as scientists note, are traditionally used to estimate sea level rise, but this information is not always absolutely accurate and often contains large time gaps.

“These averages do not reflect how the sea actually grows. Tire gauges are usually located along the coast. Because of this, large areas of the ocean are not included in these estimates, and if they are included, they usually contain large “holes,” Carling Hay from Harvard University (USA) is quoted in the article.

As another author of the article, Harvard oceanographer Eric Morrow, adds, until the early 1950s, humanity did not conduct systematic observations of sea levels at the global level, which is why we have almost no reliable information about how quickly the global sea level was rising. ocean in the first half of the 20th century.