Let's consider such a phenomenon as periodic ice ages on Earth. In modern geology, it is generally accepted that our Earth periodically experiences Ice Ages in its history. During these eras, the Earth's climate becomes sharply colder, and the Arctic and Antarctic polar caps monstrously increase in size. Not so many thousands of years ago, as we were taught, vast areas of Europe and North America were covered with ice. Eternal ice lay not only on the slopes of high mountains, but also covered the continents in a thick layer even in temperate latitudes. Where the Hudson, Elbe and Upper Dnieper flow today was a frozen desert. All this looked like an endless glacier that now covers the island of Greenland. There are signs that the retreat of the glaciers was stopped by new ice masses and that their boundaries varied at different times. Geologists can determine the boundaries of glaciers. Traces of five or six successive movements of ice during the ice age, or five or six ice ages, have been discovered. Some force pushed the ice layer towards moderate latitudes. To this day, neither the reason for the appearance of glaciers nor the reason for the retreat of the ice desert is known; the timing of this retreat is also a matter of debate. Many ideas and conjectures have been put forward to explain how the Ice Age arose and why it ended. Some believed that the Sun emitted more or less heat at different times, which explained periods of heat or cold on Earth; but we do not have sufficient evidence that the Sun is such a "changing star" as to accept this hypothesis. The cause of the ice age is seen by some scientists as a decrease in the initially high temperature of the planet. Warm periods between glacial periods were associated with heat released from the supposed decomposition of organisms in layers close to the earth's surface. Increases and decreases in hot spring activity were also taken into account.

Many ideas and conjectures have been put forward to explain how the Ice Age arose and why it ended. Some believed that the Sun emitted more or less heat at different times, which explained periods of heat or cold on Earth; but we do not have sufficient evidence that the Sun is such a "changing star" as to accept this hypothesis.

Others have argued that there are colder and warmer zones in outer space. As our solar system passes through cold regions, ice moves down latitude closer to the tropics. But no physical factors have been discovered that create such cold and warm zones in space.

Some have wondered whether precession, or the slow change in direction of the Earth's axis, could cause periodic fluctuations in climate. But it has been proven that this change alone cannot be significant enough to cause an ice age.

Scientists also looked for an answer in periodic variations in the eccentricity of the ecliptic (Earth's orbit) with the phenomenon of glaciation at maximum eccentricity. Some researchers believed that winter at aphelion, the most distant part of the ecliptic, could lead to glaciation. And others believed that such an effect could be caused by summer at aphelion.

The cause of the ice age is seen by some scientists as a decrease in the initially high temperature of the planet. Warm periods between glacial periods were associated with heat released from the supposed decomposition of organisms in layers close to the earth's surface. Increases and decreases in hot spring activity were also taken into account.

There is a view that dust of volcanic origin filled the earth's atmosphere and caused isolation, or, on the other hand, the increasing amount of carbon monoxide in the atmosphere prevented the reflection of heat rays from the surface of the planet. An increase in the amount of carbon monoxide in the atmosphere can cause a drop in temperature (Arrhenius), but calculations have shown that this could not be the true cause of the ice age (Angström).

All other theories are also hypothetical. The phenomenon that underlies all these changes has never been precisely defined, and those that have been named could not produce a similar effect.

Not only are the reasons for the appearance and subsequent disappearance of ice sheets unknown, but also the geographical relief of the area covered by ice remains a problem. Why did ice cover in the southern hemisphere move from tropical Africa towards the south pole, and not in the opposite direction? And why, in the northern hemisphere, did ice move into India from the equator towards the Himalayas and higher latitudes? Why did glaciers cover most of North America and Europe, while Northern Asia was free of them?

In America, the ice plain extended to a latitude of 40° and even crossed this line; in Europe it reached a latitude of 50°, and North-Eastern Siberia, above the Arctic Circle, even at a latitude of 75° was not covered with this eternal ice. All hypotheses concerning increasing and decreasing insulation associated with changes in the sun or temperature fluctuations in outer space, and other similar hypotheses, cannot but face this problem.

Glaciers formed in permafrost areas. For this reason, they remained on the slopes of high mountains. Northern Siberia is the coldest place on Earth. Why did the Ice Age not affect this area, although it covered the Mississippi basin and all of Africa south of the equator? No satisfactory answer to this question has been proposed.

During the Last Ice Age at the peak of glaciation, which was observed 18,000 years ago (on the eve of the Great Flood), the boundaries of the glacier in Eurasia ran approximately at 50° north latitude (the latitude of Voronezh), and the boundary of the glacier in North America even at 40° (the latitude New York). At the South Pole, glaciation affected southern South America, and possibly New Zealand and southern Australia.

The theory of ice ages was first outlined in the work of the father of glaciology, Jean Louis Agassiz, “Etudes sur les glaciers” (1840). Over the century and a half since then, glaciology has been replenished with a huge amount of new scientific data, and the maximum boundaries of the Quaternary glaciation were determined with a high degree of accuracy.
However, over the entire existence of glaciology, it has not been able to establish the most important thing - to determine the causes of the onset and retreat of ice ages. None of the hypotheses put forward during this time received approval from the scientific community. And today, for example, in the Russian-language Wikipedia article “Ice Age” you will not find the section “Causes of Ice Ages”. And not because they forgot to place this section here, but because no one knows these reasons. What are the real reasons?
Paradoxically, in fact, there have never been any ice ages in the history of the Earth. The temperature and climate regime of the Earth is determined mainly by four factors: the intensity of the Sun's glow; the orbital distance of the Earth from the Sun; the angle of inclination of the Earth's axial rotation to the ecliptic plane; as well as the composition and density of the earth's atmosphere.

These factors, as scientific data show, remained stable throughout at least the last Quaternary period. Consequently, there were no reasons for a sharp change in the Earth's climate towards cooling.

What is the reason for the monstrous growth of glaciers during the Last Ice Age? The answer is simple: in the periodic change in the location of the earth's poles. And here we should immediately add: the monstrous growth of the Glacier during the Last Ice Age is an apparent phenomenon. In fact, the total area and volume of the Arctic and Antarctic glaciers have always remained approximately constant - while the North and South Poles changed their position with an interval of 3,600 years, which predetermined the wandering of the polar glaciers (caps) on the surface of the Earth. Exactly as much glacier formed around the new poles as it melted in the places where the poles left. In other words, the ice age is a very relative concept. When the North Pole was in North America, there was an ice age for its inhabitants. When the North Pole moved to Scandinavia, the Ice Age began in Europe, and when the North Pole “went” into the East Siberian Sea, the Ice Age “came” to Asia. Currently, the ice age is severe for the supposed inhabitants of Antarctica and the former inhabitants of Greenland, which is constantly thawing in the southern part, since the previous pole shift was not strong and moved Greenland a little closer to the equator.

Thus, there have never been ice ages in the history of the Earth, and at the same time they always exist. Such is the paradox.

The total area and volume of glaciation on planet Earth has always been, is and will be generally constant as long as the four factors that determine the Earth's climate regime remain constant.
During the pole shift period, there are several ice sheets on Earth at the same time, usually two melting and two newly formed - this depends on the angle of crustal displacement.

Pole shifts on Earth occur at intervals of 3,600-3,700 years, corresponding to the period of Planet X's orbit around the Sun. These pole shifts lead to a redistribution of hot and cold zones on Earth, which is reflected in modern academic science in the form of continuously alternating stadials (cooling periods) and interstadials (warming periods). The average duration of both stadials and interstadials is determined in modern science to be 3700 years, which correlates well with the period of Planet X’s revolution around the Sun - 3600 years.

From academic literature:

It must be said that in the last 80,000 years the following periods (years BC) have been observed in Europe:
Stadial (cooling) 72500-68000
Interstadial (warming) 68000-66500
Stadial 66500-64000
Interstadial 64000-60500
Stadial 60500-48500
Interstadial 48500-40000
Stadial 40000-38000
Interstadial 38000-34000
Stadial 34000-32500
Interstadial 32500-24000
Stadial 24000-23000
Interstadial 23000-21500
Stadial 21500-17500
Interstadial 17500-16000
Stadial 16000-13000
Interstadial 13000-12500
Stadial 12500-10000

Thus, over the course of 62 thousand years, 9 stadials and 8 interstadials occurred in Europe. The average duration of a stadial is 3700 years, and an interstadial is also 3700 years. The largest stadial lasted 12,000 years, and the interstadial lasted 8,500 years.

In the post-Flood history of the Earth, 5 pole shifts occurred and, accordingly, in the Northern Hemisphere 5 polar ice sheets successively replaced each other: the Laurentian Ice Sheet (the last antediluvian), the Scandinavian Barents-Kara Ice Sheet, the East Siberian Ice Sheet, the Greenland Ice Sheet and the modern Arctic ice sheet.

The modern Greenland Ice Sheet deserves special attention as the third major ice sheet, coexisting simultaneously with the Arctic Ice Sheet and the Antarctic Ice Sheet. The presence of a third large ice sheet does not at all contradict the theses stated above, since it is a well-preserved remnant of the previous Northern Polar Ice Sheet, where the North Pole was located during 5,200 - 1,600 years. BC This fact is connected with the solution to the riddle of why the extreme north of Greenland today is not affected by glaciation - the North Pole was in the south of Greenland.

The location of the polar ice sheets in the southern hemisphere changed accordingly:

• 16,000 BCuh. (18,000 years ago) Recently, there has been a strong consensus in academic science regarding the fact that this year was both the peak of maximum glaciation of the Earth and the beginning of the rapid melting of the Glacier. There is no clear explanation for either fact in modern science. What was this year famous for? 16,000 BC e. - this is the year of the 5th passage through the solar system, counting from the present moment ago (3600 x 5 = 18,000 years ago). That year, the North Pole was located on the territory of modern Canada in the Hudson Bay region. The South Pole was located in the ocean east of Antarctica, suggesting glaciation in southern Australia and New Zealand. Eurasia is completely free of glaciers. “In the 6th year of K’an, the 11th day of Muluk, in the month of Sak, a terrible earthquake began and continued without interruption until the 13th of Kuen. The Land of Clay Hills, the Land of Mu, was sacrificed. After experiencing two strong fluctuations, it suddenly disappeared during the night;the soil was constantly shaking under the influence of underground forces, raising and lowering it in many places, so that it sank; countries separated from one another, then fell apart. Unable to resist these terrible tremors, they failed, dragging the inhabitants with them. This happened 8050 years before this book was written."(“Code of Troano” translated by Auguste Le Plongeon). The unprecedented scale of the catastrophe caused by the passage of Planet X led to a very strong pole shift. The North Pole moves from Canada to Scandinavia, the South Pole moves to the ocean west of Antarctica. At the same time the Laurentian Ice Sheet begins to rapidly melt, which coincides with the data of academic science about the end of the peak of glaciation and the beginning of the melting of the Glacier, the Scandinavian Ice Sheet is formed. At the same time, the Australian and South Zealand ice sheets are melting and the Patagonian Ice Sheet is forming in South America. These four ice sheets coexist only for the relatively short time required for the previous two ice sheets to completely melt and two new ones to form.

• 12,400 BC The North Pole moves from Scandinavia to the Barents Sea. This creates the Barents-Kara Ice Sheet, but the Scandinavian Ice Sheet melts only slightly as the North Pole moves a relatively small distance. In academic science, this fact is reflected as follows: “The first signs of the interglacial (which continues to this day) appeared already 12,000 BC.”
• 8800 BC The North Pole moves from the Barents Sea to the East Siberian Sea, due to which the Scandinavian and Barents-Kara ice sheets melt, and the East Siberian Ice Sheet is formed. This pole shift killed off most of the mammoths. Quoting from an academic study: “About 8000 BC. e. sharp warming led to the retreat of the glacier from its last line - a wide strip of moraines stretching from central Sweden through the Baltic Sea basin to south-east Finland. Around this time, the disintegration of a single and homogeneous periglacial zone occurs. In the temperate zone of Eurasia, forest vegetation predominates. To the south of it, forest-steppe and steppe zones take shape.”
• 5200 BC The North Pole moves from the East Siberian Sea to Greenland, causing the East Siberian Ice Sheet to melt and form the Greenland Ice Sheet. Hyperborea is freed from ice, and a wonderful temperate climate is established in the Trans-Urals and Siberia. Aryavarta, the land of the Aryans, flourishes here.
• 1600 BC Past shift. The North Pole moves from Greenland to the Arctic Ocean to its present position. The Arctic Ice Sheet appears, but at the same time the Greenland Ice Sheet persists. The last mammoths living in Siberia freeze very quickly with undigested green grass in their stomachs. Hyperborea is completely hidden under the modern Arctic ice sheet. Most of the Trans-Urals and Siberia become unsuitable for human existence, which is why the Aryans undertook their famous Exodus to India and Europe, and the Jews also made their exodus from Egypt.

“In the permafrost of Alaska... one can find... evidence of atmospheric disturbances of incomparable power. Mammoths and bison were torn to pieces and twisted as if some cosmic hands of the gods were at work in fury. In one place... they discovered the front leg and shoulder of a mammoth; the blackened bones still held remnants of soft tissue adjacent to the spine along with tendons and ligaments, and the chitinous shell of the tusks was not damaged. There were no traces of dismemberment of the carcasses with a knife or other weapon (as would be the case if hunters were involved in the dismemberment). The animals were simply torn apart and scattered across the area like products made from woven straw, although some of them weighed several tons. Mixed in with the accumulations of bones are trees, also torn, twisted and tangled; all this is covered with fine-grained quicksand, subsequently tightly frozen” (H. Hancock, “Traces of the Gods”).

Frozen mammoths

Northeastern Siberia, which was not covered by glaciers, holds another secret. Its climate has changed dramatically since the end of the Ice Age, and the average annual temperature has fallen many degrees lower than before. The animals that once lived in the area could no longer live here, and the plants that once grew there were unable to grow here anymore. This change must have happened quite suddenly. The reason for this event is not explained. During this catastrophic climate change and under mysterious circumstances, all Siberian mammoths died. And this happened only 13 thousand years ago, when the human race was already widespread throughout the planet. For comparison: Late Paleolithic cave paintings found in caves in Southern France (Lascaux, Chauvet, Rouffignac, etc.) were made 17-13 thousand years ago.

There lived such an animal on earth - a mammoth. They reached a height of 5.5 meters and a body weight of 4-12 tons. Most mammoths died out about 11-12 thousand years ago during the last cold spell of the Vistula Ice Age. Science tells us this, and paints a picture like the one above. True, without being very concerned with the question - what did these woolly elephants weighing 4-5 tons eat in such a landscape? “Of course, since they say so in books”- Aleni nods. Reading very selectively and looking at the picture provided. The fact that during the life of mammoths, birch trees grew on the territory of the current tundra (which is written about in the same book, and other deciduous forests - i.e. a completely different climate) - is somehow not noticed. The diet of mammoths was mainly plant-based, and adult males They ate about 180 kg of food every day.

At that time the number of woolly mammoths was truly impressive. For example, between 1750 and 1917, trade in mammoth ivory flourished over a wide area, and 96,000 mammoth tusks were discovered. According to various estimates, about 5 million mammoths lived in a small part of northern Siberia.

Before their extinction, woolly mammoths inhabited large parts of our planet. Their remains were found throughout the area Northern Europe, Northern Asia and North America.

Woolly mammoths were not a new species. They inhabited our planet for six million years.

A biased interpretation of the mammoth's hair and fat constitution, as well as a belief in constant climatic conditions, led scientists to the conclusion that the woolly mammoth was an inhabitant of the cold regions of our planet. But fur-bearing animals do not have to live in a cold climate. Take for example desert animals like camels, kangaroos and fennec foxes. They are furry, but live in hot or temperate climates. In fact most fur-bearing animals would not be able to survive in arctic conditions.

For successful cold adaptation, it is not enough just to have a coat. For adequate thermal insulation from the cold, the wool must be in a raised state. Unlike Antarctic fur seals, mammoths lacked raised fur.

Another factor in sufficient protection from cold and humidity is the presence of sebaceous glands, which secrete oils onto the skin and fur, and thus protect against moisture.

Mammoths had no sebaceous glands, and their dry hair allowed snow to touch the skin, melt, and greatly increase heat loss (the thermal conductivity of water is about 12 times higher than that of snow).

As you can see in the photo above, mammoth fur was not dense. By comparison, the fur of the yak (a cold-adapted Himalayan mammal) is about 10 times thicker.

In addition, mammoths had hair that hung down to their toes. But every Arctic animal has fur, not hair, on its toes or paws. Hair would collect snow on the ankle joint and interfere with walking.

The above clearly shows that fur and body fat are not evidence of adaptation to cold. The fat layer only indicates the abundance of food. A fat, overfed dog would not be able to withstand an Arctic blizzard and temperatures of -60°C. But Arctic rabbits or caribou can, despite their relatively low fat content relative to their total body weight.

As a rule, the remains of mammoths are found with the remains of other animals, such as: tigers, antelopes, camels, horses, reindeer, giant beavers, giant bulls, sheep, musk oxen, donkeys, badgers, alpine goats, woolly rhinoceroses, foxes, giant bison, lynx, leopards, wolverines, hares, lions, moose, giant wolves, gophers, cave hyenas, bears, as well as many species of birds. Most of these animals would not be able to survive in the Arctic climate. This is further evidence that Woolly mammoths were not polar animals.

A French prehistoric expert, Henry Neville, conducted the most detailed study of mammoth skin and hair. At the end of his careful analysis he wrote the following:

“It does not seem to me possible to find in the anatomical study of their skin and [hair] any argument in favor of adaptation to cold.”

— G. Neville, On the Extinction of the Mammoth, Annual Report of the Smithsonian Institution, 1919, p. 332.

Finally, the diet of mammoths contradicts the diet of animals living in polar climates. How could a woolly mammoth maintain its vegetarian diet in the Arctic region, and eat hundreds of kilograms of greens every day, when in such a climate there are no greens for most of the year? How could woolly mammoths find liters of water for daily consumption?

To make matters worse, woolly mammoths lived during the Ice Age, when temperatures were lower than they are today. Mammoths would not have been able to survive in the harsh climate of northern Siberia today, let alone 13 thousand years ago, if the then climate had been much harsher.

The above facts indicate that the woolly mammoth was not a polar animal, but lived in a temperate climate. Consequently, at the beginning of the Younger Dryas, 13 thousand years ago, Siberia was not an Arctic region, but a temperate one.

“However, they died a long time ago”– the reindeer herder agrees, cutting off a piece of meat from the found carcass to feed the dogs.

"Hard"- says the more vital geologist, chewing a piece of shish kebab taken from an improvised skewer.

The frozen mammoth meat initially looked absolutely fresh, dark red in color, with appetizing streaks of fat, and the expedition staff even wanted to try eating it. But as it thawed, the meat became flabby, dark gray in color, with an unbearable smell of decomposition. However, the dogs happily ate the millennia-old ice cream delicacy, from time to time starting internecine fights over the most delicious morsels.

One more thing. Mammoths are rightly called fossils. Because nowadays they are simply dug. For the purpose of extracting tusks for crafts.

It is estimated that over two and a half centuries in northeastern Siberia, tusks belonging to at least forty-six thousand (!) mammoths were collected (the average weight of a pair of tusks is close to eight pounds - about one hundred and thirty kilograms).

Mammoth tusks DIGGING. That is, they are mined from underground. Somehow the question does not even arise - why have we forgotten how to see the obvious? Did mammoths dig holes for themselves, lie down in them for winter hibernation, and then they were covered? But how did they end up underground? At a depth of 10 meters or more? Why are mammoth tusks dug out of cliffs on river banks? Moreover, in large numbers. So massively that a bill has been submitted to the State Duma equating mammoths to minerals, as well as introducing a tax on their extraction.

But for some reason they are digging them en masse only in our north. And now the question arises - what happened that entire mammoth cemeteries were formed here?

What caused such an almost instant mass pestilence?

Over the past two centuries, numerous theories have been proposed that attempt to explain the sudden extinction of woolly mammoths. They became stranded in frozen rivers, overhunted, and fell into icy crevasses at the height of the global glaciation. But Neither theory adequately explains this mass extinction.

Let's try to think for ourselves.

Then the following logical chain should line up:

1. There were a lot of mammoths.
2. Since there were many of them, they must have had a good food supply - not the tundra, where they are now found.
3. If it was not the tundra, the climate in those places was somewhat different, much warmer.
4. A slightly different climate beyond the Arctic Circle could only exist if it was not beyond the Arctic Circle at that time.
5. Mammoth tusks, and even whole mammoths themselves, are found underground. They somehow got there, some event happened that covered them with a layer of soil.
6. Taking it as an axiom that mammoths themselves did not dig holes, this soil could only have been brought by water, first surging in and then draining.
7. The layer of this soil is thick - meters, and even tens of meters. And the amount of water that applied such a layer must have been very large.
8. Mammoth carcasses are found in very well-preserved condition. Immediately after washing the corpses with sand, they froze, which was very fast.

They froze almost instantly on giant glaciers, the thickness of which was many hundreds of meters, to which they were carried by a tidal wave caused by a change in the angle of inclination of the earth's axis. This gave rise to an unjustified assumption among scientists that the animals of the middle zone went deep to the North in search of food. All the remains of mammoths were found in sands and clays deposited by mud flows.

Such powerful mudflows are possible only during extraordinary major disasters, because at this time dozens, and possibly hundreds and thousands of animal cemeteries were formed throughout the North, in which not only the inhabitants of the northern regions, but also animals from regions with a temperate climate ended up being washed away . And this allows us to believe that these gigantic animal cemeteries were formed by a tidal wave of incredible power and size, which literally rolled across the continents and, moving back into the ocean, took with it thousands of herds of large and small animals. And the most powerful mudflow “tongue”, containing gigantic accumulations of animals, reached the New Siberian Islands, which were literally covered with loess and countless bones of a wide variety of animals.

A giant tidal wave washed away gigantic herds of animals from the face of the Earth. These huge herds of drowned animals, lingering in natural barriers, folds of terrain and floodplains, formed countless animal cemeteries in which animals from various climatic zones found themselves mixed.

Scattered bones and molars of mammoths are often found in sediments and sediments on the ocean floor.

The most famous, but far from the largest mammoth cemetery in Russia, is the Berelekh burial site. This is how N.K. describes the Berelekh mammoth cemetery. Vereshchagin: “The yar is crowned with a melting edge of ice and mounds... A kilometer later, a vast scattering of huge gray bones appeared - long, flat, short. They protrude from the dark damp soil in the middle of the slope of the ravine. Sliding toward the water along a weakly turfed slope, the bones formed a spit-toe that protected the shore from erosion. There are thousands of them, the scattering stretches along the shore for about two hundred meters and goes into the water. The opposite, right bank is only eighty meters away, low, alluvial, behind it is an impenetrable thicket of willow... everyone is silent, depressed by what they see.”.In the area of ​​the Berelekh cemetery there is a thick layer of clay-ash loess. Signs of extremely large floodplain sediment are clearly visible. A huge mass of fragments of branches, roots, and bone remains of animals had accumulated in this place. The animal cemetery was washed away by the river, which twelve thousand years later returned to its former course. Scientists who studied the Berelekh cemetery discovered among the remains of mammoths, a large number of bones of other animals, herbivores and predators, which under normal conditions are never found in huge concentrations together: foxes, hares, deer, wolves, wolverines and other animals.

The theory of recurring catastrophes destroying life on our planet and repeating the creation, or restoration of life forms, proposed by Deluc and developed by Cuvier, did not convince the scientific world. Both Lamarck before Cuvier and Darwin after him believed that a progressive, slow, evolutionary process governs genetics and that there are no catastrophes that interrupt this process of infinitesimal changes. According to the theory of evolution, these minor changes are the result of adaptation to living conditions in the struggle of species for survival.

Darwin admitted that he was unable to explain the disappearance of the mammoth, an animal much more advanced than the elephant, which survived. But in accordance with the theory of evolution, his followers believed that the gradual subsidence of the soil forced the mammoths to climb the hills, and they turned out to be closed on all sides by swamps. However, if geological processes are slow, mammoths would not be trapped on isolated hills. Moreover, this theory cannot be true because the animals did not die from starvation. Undigested grass was found in their stomachs and between their teeth. This, by the way, also proves that they died suddenly. Further research showed that the branches and leaves found in their stomachs did not come from the areas where the animals died, but further south, more than a thousand miles away. It appears that the climate has changed radically since the death of the mammoths. And since the bodies of the animals were found undecomposed, but well preserved in ice blocks, a change in temperature must have followed immediately after their death.

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Risking their lives and exposing themselves to great danger, scientists in Siberia are searching for one single frozen mammoth cell. With the help of which it will be possible to clone and thereby bring back to life a long-extinct species of animal.

It remains to add that after storms in the Arctic, mammoth tusks are washed up on the shores of the Arctic islands. This proves that the part of the land where the mammoths lived and drowned was heavily flooded.

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For some reason, modern scientists do not take into account the facts of the presence of a geotectonic catastrophe in the Earth’s recent past. Precisely in the recent past.
Although for them it is already an indisputable fact of the catastrophe that killed the dinosaurs. But they also date this event to 60-65 million years ago.
There are no versions that would combine the temporal facts of the death of dinosaurs and mammoths - at one time. Mammoths lived in temperate latitudes, dinosaurs - in the southern regions, but died at the same time.
But no, no attention is paid to the geographical attachment of animals from different climatic zones, but there is also a temporary separation.
There have already been many facts about the sudden death of a huge number of mammoths in different parts of the world. But here scientists again avoid obvious conclusions.
Not only have representatives of science aged all the mammoths by 40 thousand years, but they are also inventing versions of the natural processes in which these giants died.

American, French and Russian scientists conducted the first CT scans of Lyuba and Khroma, the youngest and best-preserved mammoth calves.

Computed tomography (CT) sections were presented in the new issue of the Journal of Paleontology, and a summary of the results of the work can be found on the University of Michigan website.

Reindeer herders found Lyuba in 2007, on the banks of the Yuribey River on the Yamal Peninsula. Her corpse reached the scientists almost without damage (only the tail was chewed off by dogs).

Khroma (this is “boy”) was discovered in 2008 on the banks of the river of the same name in Yakutia - crows and arctic foxes ate his trunk and part of his neck. Mammoths have well-preserved soft tissues (muscles, fat, internal organs, skin). Khroma was even found with coagulated blood in intact vessels and undigested milk in her stomach. Chroma was scanned at a French hospital. And at the University of Michigan, scientists made CT sections of animal teeth.

Thanks to this, it turned out that Lyuba died at the age of 30-35 days, and Chroma - 52-57 days (and both mammoths were born in the spring).

Both baby mammoths died after choking on mud. CT scans showed a dense mass of fine-grained deposits blocking the airways in the trunk.

The same deposits are present in Lyuba’s throat and bronchi - but not inside her lungs: this suggests that Lyuba did not drown in the water (as was previously thought), but suffocated by inhaling liquid mud. Khroma's spine was broken and there was also dirt in his respiratory tract.

So, scientists have once again confirmed our version of a global mudflow that covered the present north of Siberia and destroyed all life there, covering a vast area with “fine-grained sediments that clogged the respiratory tract.”

After all, such finds are observed over a vast territory and to assume that all the found mammoths suddenly AT THE SAME TIME and en masse began to fall into rivers and swamps is absurd.

Plus, the mammoth calves have typical injuries for those caught in a stormy mudflow - broken bones and spine.

Scientists have found a very interesting detail - the death occurred either at the end of spring or in summer. After birth in the spring, mammoth calves lived for 30-50 days before death. That is, the time of the pole change was probably in the summer.

Or here's another example:

A team of Russian and American paleontologists is studying a bison that has lain in permafrost in northeastern Yakutia for about 9,300 years.

The bison found on the shores of Lake Chukchalakh is unique in that it is the first representative of this bovid species found at such a respectable age in complete preservation - with all parts of the body and internal organs.

He was found in a supine position with his legs bent under his abdomen, his neck extended and his head lying on the ground. Usually, ungulates rest or sleep in this position, and in this position they die a natural death.

The age of the body, determined using radiocarbon analysis, is 9310 years, that is, the bison lived in the early Holocene era. Scientists also determined that his age before death was about four years. The bison managed to grow to 170 cm at the withers, the span of the horns reached an impressive 71 cm, and the weight was about 500 kg.

Researchers have already scanned the animal's brain, but the cause of its death still remains a mystery. No damage was found on the corpse, nor were there any pathologies of internal organs or dangerous bacteria.

There have been long periods in Earth's history when the entire planet was warm, from the equator to the poles. But there were also times so cold that glaciations reached those regions that currently belong to the temperate zones. Most likely, the change of these periods was cyclical. During warm times, ice could be relatively scarce and found only in polar regions or on mountain tops. An important feature of ice ages is that they change the nature of the earth's surface: each glaciation affects the appearance of the earth. These changes themselves may be small and insignificant, but they are permanent.

History of Ice Ages

We don't know exactly how many ice ages there have been throughout Earth's history. We know of at least five, possibly seven ice ages, starting with the Precambrian, in particular: 700 million years ago, 450 million years ago (Ordovician period), 300 million years ago - Permian-Carboniferous glaciation, one of the largest ice ages, affecting the southern continents. The southern continents mean the so-called Gondwana - an ancient supercontinent that included Antarctica, Australia, South America, India and Africa.

The most recent glaciation refers to the period in which we live. The Quaternary period of the Cenozoic era began about 2.5 million years ago, when the glaciers of the Northern Hemisphere reached the sea. But the first signs of this glaciation date back to 50 million years ago in Antarctica.

The structure of each ice age is periodic: there are relatively short warm periods, and there are longer periods of icing. Naturally, cold periods are not the result of glaciation alone. Glaciation is the most obvious consequence of cold periods. However, there are quite long intervals that are very cold, despite the absence of glaciations. Today, examples of such regions are Alaska or Siberia, where it is very cold in winter, but there is no glaciation because there is not enough precipitation to provide enough water for the formation of glaciers.

Discovery of Ice Ages

We have known that there are ice ages on Earth since the mid-19th century. Among the many names associated with the discovery of this phenomenon, the first is usually the name of Louis Agassiz, a Swiss geologist who lived in the mid-19th century. He studied the glaciers of the Alps and realized that they were once much more extensive than they are today. He wasn't the only one who noticed this. In particular, Jean de Charpentier, another Swiss, also noted this fact.

It is not surprising that these discoveries were made mainly in Switzerland, since glaciers still exist in the Alps, although they are melting quite quickly. It is easy to see that glaciers were once much larger - just look at the Swiss landscape, troughs (glacial valleys) and so on. However, it was Agassiz who first put forward this theory in 1840, publishing it in the book “Étude sur les glaciers”, and later, in 1844, he developed this idea in the book “Système glaciare”. Despite initial skepticism, over time people began to realize that this was indeed true.

With the advent of geological mapping, especially in Northern Europe, it became clear that glaciers used to be of enormous scale. There was considerable discussion at the time about how this information related to the Flood because there was a conflict between geological evidence and biblical teachings. Initially, glacial deposits were called colluvial because they were considered evidence of the Great Flood. Only later did it become known that this explanation was not suitable: these deposits were evidence of a cold climate and extensive glaciations. By the beginning of the twentieth century, it became clear that there were many glaciations, not just one, and from that moment this field of science began to develop.

Ice Age Research

Geological evidence of ice ages is known. The main evidence for glaciations comes from the characteristic deposits formed by glaciers. They are preserved in the geological section in the form of thick ordered layers of special sediments (sediments) - diamicton. These are simply glacial accumulations, but they include not only the deposits of a glacier, but also deposits of meltwater formed by meltwater streams, glacial lakes or glaciers moving out to sea.

There are several forms of glacial lakes. Their main difference is that they are a body of water surrounded by ice. For example, if we have a glacier that rises into a river valley, then it blocks the valley, like a cork in a bottle. Naturally, when ice blocks a valley, the river will still flow and the water level will rise until it overflows. Thus, a glacial lake is formed through direct contact with ice. There are certain sediments that are contained in such lakes that we can identify.

Because of the way glaciers melt, which depends on seasonal temperature changes, ice melts occur annually. This leads to an annual increase in minor sediments that fall from under the ice into the lake. If we then look into the lake, we see stratification (rhythmic layered sediments), which are also known by the Swedish name “varve”, which means “annual accumulation”. So we can actually see annual layering in glacial lakes. We can even count these varves and find out how long this lake existed. In general, with the help of this material we can get a lot of information.

In Antarctica we can see huge ice shelves that flow from the land into the sea. And naturally, ice is buoyant, so it floats on water. As it floats, it carries pebbles and minor sediments with it. The thermal effects of the water cause the ice to melt and shed this material. This leads to the formation of a process called rafting of rocks that go into the ocean. When we see fossil deposits from this period, we can find out where the glacier was, how far it extended, and so on.

Causes of glaciations

Researchers believe that ice ages occur because the Earth's climate depends on the uneven heating of its surface by the Sun. For example, the equatorial regions, where the Sun is almost vertically overhead, are the warmest zones, and the polar regions, where it is at a large angle to the surface, are the coldest. This means that differences in heating of different parts of the Earth's surface drive the ocean-atmospheric machine, which is constantly trying to transfer heat from the equatorial regions to the poles.

If the Earth were an ordinary sphere, this transfer would be very efficient, and the contrast between the equator and the poles would be very small. This has happened in the past. But since there are now continents, they stand in the way of this circulation, and the structure of its flows becomes very complex. Simple currents are constrained and altered—largely by mountains—leading to the circulation patterns we see today that drive trade winds and ocean currents. For example, one theory about why the ice age began 2.5 million years ago links this phenomenon to the emergence of the Himalayan mountains. The Himalayas are still growing very quickly, and it turns out that the existence of these mountains in a very warm part of the Earth controls things like the monsoon system. The onset of the Quaternary Ice Age is also associated with the closure of the Isthmus of Panama, which connects north and south America, which prevented the transfer of heat from the equatorial Pacific to the Atlantic.

If the location of the continents relative to each other and relative to the equator allowed circulation to work effectively, then it would be warm at the poles, and relatively warm conditions would persist throughout the earth's surface. The amount of heat received by the Earth would be constant and vary only slightly. But since our continents create serious barriers to circulation between north and south, we have distinct climatic zones. This means that the poles are relatively cold and the equatorial regions are warm. When things are as they are now, the Earth can change due to variations in the amount of solar heat it receives.

These variations are almost completely constant. The reason for this is that over time, the earth's axis changes, as does the earth's orbit. Given this complex climate zoning, orbital changes could contribute to long-term changes in climate, leading to climate fluctuations. Because of this, we do not have continuous icing, but periods of icing, interrupted by warm periods. This occurs under the influence of orbital changes. The latest orbital changes are considered as three separate events: one lasting 20 thousand years, the second lasting 40 thousand years, and the third lasting 100 thousand years.

This led to deviations in the pattern of cyclical climate changes during the Ice Age. The icing most likely occurred during this cyclic period of 100 thousand years. The last interglacial period, which was as warm as the current one, lasted about 125 thousand years, and then came the long ice age, which took about 100 thousand years. We are now living in another interglacial era. This period will not last forever, so another ice age awaits us in the future.

Why do ice ages end?

Orbital changes change the climate, and it turns out that ice ages are characterized by alternating cold periods, which can last up to 100 thousand years, and warm periods. We call them the glacial (glacial) and interglacial (interglacial) eras. The interglacial era is usually characterized by approximately the same conditions that we see today: high sea levels, limited areas of glaciation, and so on. Naturally, glaciations still exist in Antarctica, Greenland and other similar places. But in general, the climatic conditions are relatively warm. This is the essence of the interglacial: high sea levels, warm temperature conditions and a generally fairly even climate.

But during the Ice Age, the average annual temperature changes significantly, and vegetative zones are forced to shift north or south, depending on the hemisphere. Regions like Moscow or Cambridge are becoming uninhabited, at least in winter. Although they can be inhabited in summer due to the strong contrast between the seasons. But what is actually happening is that the cold zones are expanding significantly, the average annual temperature is decreasing, and overall climate conditions are becoming very cold. While the largest glacial events are relatively limited in time (perhaps about 10 thousand years), the entire Long Cold Period can last 100 thousand years or even more. This is what glacial-interglacial cyclicity looks like.

Due to the length of each period, it is difficult to say when we will exit the current era. This is due to plate tectonics, the location of continents on the surface of the Earth. Currently, the North Pole and South Pole are isolated: Antarctica is at the South Pole and the Arctic Ocean is to the north. Because of this, there is a problem with heat circulation. Until the position of the continents changes, this ice age will continue. Based on long-term tectonic changes, it can be assumed that it will take another 50 million years in the future until significant changes occur that allow the Earth to emerge from the Ice Age.

Geological consequences

This frees up huge areas of the continental shelf that are now submerged. This will mean, for example, that one day it will be possible to walk from Britain to France, from New Guinea to Southeast Asia. One of the most critical places is the Bering Strait, which connects Alaska with Eastern Siberia. It is quite shallow, about 40 meters, so if the sea level drops to one hundred meters, this area will become dry land. This is also important because plants and animals will be able to migrate through these places and enter regions that they cannot reach today. Thus, the colonization of North America depends on the so-called Beringia.

Animals and the Ice Age

It's important to remember that we ourselves are "products" of the Ice Age: we evolved during it, so we can survive it. However, this is not a matter of individuals - it is a matter of the entire population. The problem today is that there are too many of us and our activities have significantly changed natural conditions. Under natural conditions, many of the animals and plants we see today have a long history and survive the Ice Age well, although there are those that evolve only slightly. They migrate and adapt. There are areas where animals and plants survived the Ice Age. These so-called refugia were located further north or south of their current distribution.

But as a result of human activity, some species died or became extinct. This happened on every continent, perhaps with the exception of Africa. A huge number of large vertebrates, namely mammals, as well as marsupials in Australia, were exterminated by humans. This was caused either directly by our activities, such as hunting, or indirectly by the destruction of their habitat. Animals living in northern latitudes today once lived in the Mediterranean. We have destroyed this region so much that it will likely be very difficult for these animals and plants to colonize it again.

Consequences of global warming

Under normal conditions by geological standards, we would have returned to the Ice Age fairly soon. But due to global warming, which is a consequence of human activity, we are delaying it. We will not be able to completely prevent it, since the reasons that caused it in the past still exist. Human activity, an element unintended by nature, is influencing atmospheric warming, which may already have caused a delay in the next glacial.

Today, climate change is a very pressing and exciting issue. If the Greenland Ice Sheet melts, sea levels will rise by six meters. In the past, during the previous interglacial epoch, which was approximately 125 thousand years ago, the Greenland ice sheet melted profusely, and sea levels became 4-6 meters higher than today. This, of course, is not the end of the world, but it is not a temporary difficulty either. After all, the Earth has recovered from disasters before, and it will be able to survive this one too.

The long-term forecast for the planet is not bad, but for people it is a different matter. The more research we do, the more we understand how the Earth is changing and where it is leading, the better we understand the planet we live on. This is important because people are finally starting to think about sea level change, global warming, and the impact of all these things on agriculture and populations. Much of this has to do with the study of ice ages. Through this research we are learning about the mechanisms of glaciations, and we can use this knowledge proactively to try to mitigate some of these changes that we are causing. This is one of the main results and one of the goals of ice age research.
Of course, the main consequence of the Ice Age is the huge ice sheets. Where does water come from? From the oceans, of course. What happens during ice ages? Glaciers form as a result of precipitation on land. Because water is not returned to the ocean, sea levels are falling. During the most intense glaciations, sea level can drop by more than a hundred meters.

There are several hypotheses about the causes of glaciations. The factors underlying these hypotheses can be divided into astronomical and geological. Astronomical factors causing cooling on earth include:

1. Changing the tilt of the earth's axis
2. Deviation of the Earth from its orbit away from the Sun
3. Uneven thermal radiation from the Sun.

Geological factors include mountain-forming processes, volcanic activity, and continental movement.
Each of the hypotheses has its drawbacks. Thus, the hypothesis connecting glaciation with the eras of mountain building does not explain the absence of glaciation in the Mesozoic, although mountain-building processes were quite active during this era.
The intensification of volcanic activity, according to some scientists, leads to warming of the earth's climate, while others believe it leads to cooling. According to the hypothesis of continental movement, huge areas of land throughout the history of the development of the earth's crust periodically moved from a warm climate to a cold climate, and vice versa.

During the geological history of the planet, which spans more than 4 billion years, the Earth has experienced several periods of glaciation. The oldest Huronian glaciation is 4.1 - 2.5 billion years old, the Gneissian glaciation is 900 - 950 million years old. Further ice ages were repeated quite regularly: Sturt - 810 - 710, Varangian - 680 - 570, Ordovician - 410 - 450 million years ago. The penultimate ice age on Earth was 340 - 240 million years ago and was called Gondwana. Now there is another ice age on Earth, called the Cenozoic, which began 30 - 40 million years ago with the appearance of the Antarctic ice sheet. Man appeared and lives in the Ice Age. In the last few million years, the glaciation of the Earth either grows, and then large areas in Europe, North America and partly in Asia are occupied by cover glaciers, or shrinks to the size that exists today. For the last million years, 9 such cycles have been identified. Typically, the period of growth and existence of ice sheets in the Northern Hemisphere is about 10 times longer than the period of destruction and retreat. Periods of glacier retreat are called interglacials. We are now living in the period of another interglacial, which is called the Holocene.

The central problem of cryology of the Earth is the identification and study of the general patterns of glaciation of our planet. The Earth's cryosphere experiences both continuous seasonal and periodic fluctuations and centuries-long changes.

Currently, the Earth has passed the Ice Age and is in an interglacial period. But what happens next? What is the forecast for the process of glaciation of the Earth? Could a new glacial advance begin soon?

The answers to these questions concern not only scientists. Glaciation of the Earth is a gigantic planetary process that is of concern to all humanity. To find the answer to these questions, you need to penetrate the mysteries of glaciation, reveal the patterns of development of ice ages, and establish the main reasons for their occurrence.
The works of many outstanding scientists were devoted to solving these problems. But the complexity of the issues is so great that, according to the famous climatologist M. Schwarzbach, it is almost impossible to penetrate the mystery of glaciation.

There are many theories and hypotheses that try to solve this mystery. Without going into details of all the theories and hypotheses, we can combine them into three main groups.
Planetary - where the main reason for the onset of ice ages is considered to be significant changes occurring on the planet: shifting poles, movement of continents, mountain building processes, which are accompanied by changes in the circulation of air and ocean currents and the appearance of glaciers, atmospheric pollution by products of volcanic activity, changes in the concentration of carbon dioxide and ozone in the atmosphere .

Planetary hypotheses also include astronomical hypotheses that explain the glaciation of the planet by changes in the Earth’s orbit, changes in the angle of inclination of its axis of rotation, distance from the Sun, etc.

Solar - hypotheses and theories that explain the emergence of glaciation periods by the rhythmicity of energy processes occurring in the depths of the Sun. As a result of these processes, periodic changes occur in the amount of solar energy reaching the Earth. The duration of these periods is several hundred million years, which is consistent with the periodicity of the Ice Ages.

As a first approximation, the rhythmicity of the processes of advance and retreat of glaciers within each ice age is also explained.

Space hypotheses and theories. According to them, there are cosmic factors that help explain the cyclical nature of climate change and the onset of ice ages on Earth. Such reasons may include flows of radiant energy or flows of particles that cause changes in energy processes both inside the Sun and inside the Earth, clouds of cosmic dust that partially absorb the energy of the Sun, as well as factors still unknown to us. For example, the hypothesis about the possibility of interaction of a neutrino flux with the matter of the earth's interior is of great interest. The coincidence of the period of alternation of ice ages (about 250 million years) with the period of revolution of the Solar system around the center of the Galaxy (220-230 million years) deserves close attention. Even more striking is the proximity (given the low accuracy of determining such quantities) of this period with a periodicity (about 300 million years) of waves of matter condensation in the arms of our Galaxy, which arise as a result of the ejection of gigantic masses of matter rotating at enormous speed from the center of the Galaxy. By the way, the last wave of this shock disturbance, which occurred 60 million years ago, surprisingly coincides with the geological time of the disappearance of giant reptiles at the end of the Cretaceous period of the Mesozoic era.

It seems that it is possible to understand and study the dynamics of climate and the occurrence of ice ages only on the basis of a synthesis of cosmic, solar and planetary factors.
A few words about the forecast of the thermal fate of the Earth, or more precisely, about the probabilistic course of thermal processes on astrophysical time scales.
Closely related to the problem of predicting the natural course of glaciation on our planet is the problem of artificially changing the planet’s climate. Scientists involved in cryology are faced with the task of establishing a threshold for the growth of energy production on Earth, beyond which changes in the physical-geographical shell that are very undesirable for humanity may occur (flooding of land during the melting of Antarctic and other glaciers, excessive increase in air temperature and thawing of the frozen strata of the Earth) .

What determines the decrease in the average temperature of the Earth?

It has been suggested that the cause is a change in the amount of heat received from the Sun. Above we talked about the 11-year periodicity of solar radiation. There may be longer periods. In this case, cold snaps may be associated with minimum solar radiation. An increase or decrease in temperature on Earth occurs even with a constant amount of energy coming from the Sun, and is also determined by the composition of the atmosphere.
In 1909, S. Arrhenius first emphasized the enormous role of carbon dioxide as a temperature regulator of surface layers of air. Carbon dioxide freely transmits the sun's rays to the earth's surface, but absorbs most of the earth's thermal radiation. It is a colossal screen that prevents the cooling of our planet. Currently, the carbon dioxide content in the atmosphere does not exceed 0.03%. If this figure is halved, then average annual temperatures in temperate zones will decrease by 4-5 ° C, which could lead to the onset of an ice age.

The study of modern and ancient volcanic activity allowed volcanologist I.V. Melekestsev associated the cooling and the glaciation that caused it with an increase in the intensity of volcanism. It is well known that volcanism significantly affects the earth's atmosphere, changing its gas composition, temperature, and also polluting it with finely divided volcanic ash material. Huge masses of ash, measured in billions of tons, are ejected by volcanoes into the upper atmosphere and then carried by jet streams throughout the globe. A few days after the Bezymyanny volcano erupted in 1956, its ashes were discovered in the upper troposphere over London. Ash material released during the 1963 eruption of Mount Agung on the island of Bali (Indonesia) was found at an altitude of about 20 km above North America and Australia. Pollution of the atmosphere by volcanic ash causes a significant decrease in its transparency and, consequently, a weakening of solar radiation by 10-20% against the norm. In addition, ash particles serve as condensation nuclei, contributing to large cloud development. Increasing cloudiness, in turn, significantly reduces the amount of solar radiation. According to Brooks' calculations, an increase in cloudiness from 50 (typical for the present) to 60% would lead to a decrease in the average annual temperature on the globe by 2 ° C.

Sometimes you can hear the statement that the Ice Age is already behind us and people will not have to deal with this phenomenon in the future. This would be true if we were sure that modern glaciation on the globe is just a remnant of the Great Quaternary glaciation of the Earth and should inevitably soon disappear. In fact, glaciers continue to be one of the leading components of the environment and make an important contribution to the life of our planet.

Formation of mountain glaciers

As you ascend into the mountains, the air becomes colder. At some altitude, winter snow does not have time to melt during the summer; from year to year it accumulates and gives rise to glaciers. A glacier is a mass of multi-year ice of predominantly atmospheric origin, which moves under the influence of gravity and takes the form of a stream, dome or floating slab (in the case of ice sheets and shelves).

In the upper part of the glacier there is an accumulation area where sediment accumulates, which is gradually converted into ice. Constant replenishment of snow reserves, its compaction, and recrystallization lead to the fact that it turns into a coarse-grained mass of ice grains - firn, and then, under the pressure of the overlying layers, into massive glacier ice.

From the accumulation area, ice flows to the lower part - the so-called ablation area, where it is consumed mainly by melting. The upper part of a mountain glacier is usually a firn basin. It occupies a car (or cirque - the extended upper reaches of the valley) and has a concave surface. When leaving the cirque, the glacier often crosses a high mouth step - a crossbar; Here the ice is cut through deep transverse cracks and an icefall occurs. Then the glacier descends in a relatively narrow tongue down the valley. The life of a glacier is largely determined by the balance of its mass. With a positive balance, when the flow of matter on the glacier exceeds its flow, the mass of ice increases, the glacier becomes more active, moves forward, and captures new areas. If negative, it becomes passive, retreats, freeing the valley and slopes from under the ice.

Perpetual motion

Majestic and calm, glaciers are in fact in constant movement. The so-called cirque and valley glaciers flow slowly down the slopes, and ice sheets and domes spread from the center to the periphery. This movement is determined by the force of gravity and becomes possible due to the property of ice to deform under stress. Brittle in individual fragments, in vast massifs the ice acquires plastic properties, like frozen pitch, which cracks if you hit it, but slowly flows along the surface, being “loaded” in one place. There are also frequent cases when ice with almost its entire mass slides along the bed or other layers of ice - this is the so-called block sliding of glaciers. Cracks form in the same places on the glacier, but since new ice masses are involved in this process each time, the old cracks, as the ice moves from the place of their formation, gradually “heal”, that is, they close. Individual cracks stretch across the glacier from several tens to many hundreds of meters, their depth reaches 20-30, and sometimes 50 meters or more.

The movement of thousand-ton ice masses, although very slowly, does a tremendous amount of work - over many thousands of years it transforms the face of the planet beyond recognition. Centimeter by centimeter, ice crawls along solid rocks, leaving grooves and scars on them, breaking them and carrying them with it. From the surface of the Antarctic continent, glaciers annually remove layers of rock with an average thickness of 0.05 mm. This apparent microscopic value already grows to 50 m if we take into account the entire million years of the Quaternary period, when the Antarctic continent was probably covered with ice. Many glaciers in the Alps and Caucasus have an ice movement speed of about 100 m per year. In the larger glaciers of the Tien Shan and Pamir, the ice moves 150-300 m per year, and on some Himalayan glaciers - up to 1 km, that is, 2-3 m per day.

Glaciers have a variety of sizes: from 1 km in length - for small cirque glaciers, to tens of kilometers - for large valley glaciers. The largest glacier in Asia, Fedchenko glacier, reaches a length of 77 km. In their movement, glaciers carry over many tens, or even hundreds of kilometers, blocks of rock that have fallen from mountain slopes onto their surface. Such blocks are called erratic, that is, “wandering” boulders, the composition of which differs from the local rocks.

Thousands of such boulders are found on the plains of Europe and North America, in the valleys at their exit from the mountains. The volume of some of them reaches several thousand cubic meters. Known, for example, is the giant Ermolovsky stone in the Terek riverbed, at the exit from the Daryal gorge of the Caucasus. The length of the stone exceeds 28 m, and the height is about 17 m. The source of their appearance is the places where the corresponding rocks come to the surface. In America these are the Cordilleras and Labrador, in Europe - Scandinavia, Finland, Karelia. And they were brought here from afar, from where huge ice sheets once existed, a reminder of which is the modern ice sheet of Antarctica.

The mystery of their pulsation

In the mid-20th century, people were faced with another problem - pulsating glaciers, characterized by sudden advances of their ends, without apparent connection with climate change. Hundreds of pulsating glaciers are now known in many glacial regions. Most of them are in Alaska, Iceland and Spitsbergen, in the mountains of Central Asia, and the Pamirs.

The general cause of glacial movements is the accumulation of ice in conditions where its flow is hampered by the narrowness of the valley, moraine cover, mutual damming of the main trunk and side tributaries, etc. Such accumulation creates conditions of instability that cause ice runoff: large chips, heating of the ice with the release of water during internal melting, the appearance of water and water-clay lubricant on the bed and chips. On September 20, 2002, a disaster occurred in the valley of the Genaldon River in North Ossetia. Huge masses of ice, mixed with water and stone material, burst out from the upper reaches of the valley, quickly swept down the valley, destroying everything in its path, and formed a blockage, spreading across the entire Karmadon basin in front of the ridge of the Rocky Range. The culprit of the disaster was the pulsating Kolka glacier, the movements of which occurred several times in the past.

The Kolka glacier, like many other pulsating glaciers, has difficulty draining ice. Over the course of many years, ice accumulates in front of an obstacle, increases its mass to a certain critical volume, and when the braking forces cannot resist the shear forces, a sharp release of tension occurs and the glacier advances. In the past, movements of the Kolka glacier occurred around 1835, in 1902 and 1969. They arose when the glacier accumulated a mass of 1-1.3 million tons. The Genaldon disaster of 1902 guide occurred on July 3, at the height of the hot summer. The air temperature during this period exceeded the norm by 2.7°C, and there were heavy downpours. Having turned into a pulp of ice, water and moraine, the ice ejection transformed into a crushing high-speed mudflow that rushed through in a matter of minutes. The 1969 movement developed gradually, reaching its greatest development in winter, when the amount of meltwater in the basin was minimal. This determined the relatively calm course of events. In 2002, a huge amount of water accumulated in the glacier, which became the trigger for movement. Obviously, the water “teared” the glacier from its bed and a powerful water-ice-rock mudflow formed. The fact that the movement was triggered ahead of time and reached a colossal scale was due to the existing complex of factors: the unstable dynamic state of the glacier, which had already accumulated a mass close to critical; powerful accumulation of water in the glacier and under the glacier; landslides of ice and rock, which created an overload in the rear part of the glacier.

A world without glaciers

The total volume of ice on Earth is almost 26 million km 3, or about 2% of all Earth's water. This mass of ice is equal to the flow of all the rivers of the globe over 700 years.

If the existing ice were evenly distributed over the surface of our planet, it would cover it with a layer 53 m thick. And if this ice suddenly melted, the level of the World Ocean would rise by 64 m. At the same time, densely populated fertile coastal plains over an area of ​​about 15 million would be flooded. . km 2 2 . Such a sudden melting cannot occur, but throughout geological epochs, when ice sheets arose and then gradually melted, sea level fluctuations were even greater.

Direct dependence

The influence of glaciers on the Earth's climate is enormous. In winter, extremely little solar radiation comes to the polar regions, since the Sun does not appear over the horizon and the polar night prevails here. And in the summer, due to the long duration of the polar day, the amount of radiant energy coming from the Sun is greater than even in the equator region. However, temperatures remain low as up to 80% of the incoming energy is reflected back by snow and ice. The picture would have been completely different if there had been no ice cover. In this case, almost all the heat that comes in summer would be absorbed and the temperature in the polar regions would differ from the tropical temperature to a much lesser extent. So, if there had not been the continental ice sheet of Antarctica and the ice sheet of the Arctic Ocean around the earth’s poles, there would not have been the usual division into natural zones on Earth and the entire climate would have been much more uniform. Once the ice masses at the poles melt, the polar regions will become much warmer, and rich vegetation will appear on the shores of the former Arctic Ocean and on the surface of ice-free Antarctica. This is exactly what happened on Earth in the Neogene period - just a few million years ago it had a smooth, mild climate. However, one can imagine another state of the planet, when it is completely covered with a shell of ice. After all, once formed under certain conditions, glaciers are able to grow on their own, since they lower the surrounding temperature and grow in height, thereby spreading into higher and colder layers of the atmosphere. Icebergs breaking off from large ice sheets are carried across the ocean, ending up in tropical waters, where their melting also helps cool the water and air.

If nothing prevents the formation of glaciers, then the thickness of the ice layer could increase to several kilometers due to water from the oceans, the level of which would continuously decrease. In this way, gradually all the continents would be under ice, the temperature on the surface of the Earth would drop to about -90 ° C and organic life on it would cease. Fortunately, this has not happened throughout the entire geological history of the Earth, and there is no reason to think that such glaciation could occur in the future. Currently, the Earth is experiencing a state of partial glaciation, when only a tenth of its surface is covered by glaciers. This state is unstable: glaciers either shrink or increase in size and very rarely remain unchanged.

White cover of the "blue planet"

If you look at our planet from space, you can see that some of its parts look completely white - this is the snow cover that is so familiar to the inhabitants of temperate zones.

Snow has a number of amazing properties that make it an indispensable component in Nature’s “kitchen”. The Earth's snow cover reflects more than half of the radiant energy coming to us from the Sun, the same one that covers the polar glaciers (the cleanest and driest) - in general, up to 90% of the sun's rays! However, snow also has another phenomenal property. It is known that all bodies emit thermal energy, and the darker they are, the greater the heat loss from their surface. But snow, being dazzlingly white, is capable of emitting thermal energy almost like a completely black body. The differences between them do not reach even 1%. So, even the slight heat that the snow cover has is quickly radiated into the atmosphere. As a result, the snow cools even more, and the areas of the globe covered by it become a source of cooling for the entire planet.

Features of the sixth continent

Antarctica is the highest continent on the planet, with an average height of 2,350 m (the average height of Europe is 340 m, Asia is 960 m). This altitude anomaly is explained by the fact that most of the mass of the continent is composed of ice, which is almost three times lighter than rocks. Once it was free of ice and did not differ much in height from other continents, but gradually a powerful ice shell covered the entire continent, and the earth’s crust began to bend under colossal load. Over the past millions of years, this excess load has been “isostatically compensated”, in other words, the earth’s crust has bent, but traces of it are still reflected in the Earth’s topography. Oceanographic studies of coastal Antarctic waters have shown that the continental shelf (shelf), which borders all continents with a shallow strip with depths of no more than 200 m, was 200-300 m deeper off the coast of Antarctica. The reason for this is the lowering of the earth's crust under the weight of the ice that previously covered the continental shelf 600-700 m thick. Relatively recently, the ice retreated from here, but the earth's crust has not yet had time to “unbend” and, in addition, it is held in place by ice lying to the south. The unrestricted expansion of the Antarctic ice sheet has always been hampered by the sea.

Any expansion of glaciers beyond the land is possible only under the condition that the sea near the coast is not deep, otherwise sea currents and waves will sooner or later destroy the ice that has extended far into the sea. Therefore, the boundary of maximum glaciation ran along the outer edge of the continental shelf. Antarctic glaciation in general is greatly influenced by sea level changes. When the level of the World Ocean falls, the ice sheet of the sixth continent begins to advance; when it rises, it retreats. It is known that over the past 100 years, sea level has risen by 18 cm, and continues to rise now. Apparently, the destruction of some Antarctic ice shelves, accompanied by the calving of huge table icebergs up to 150 km long, is associated with this process. At the same time, there is every reason to believe that the mass of Antarctic glaciation is increasing in the modern era, and this may also be associated with ongoing global warming. Indeed, climate warming causes increased atmospheric circulation and increased inter-latitudinal exchange of air masses. Warmer and humid air enters the Antarctic continent. However, an increase in temperature of several degrees does not cause any melting inland, where frosts are now 40-60 ° C, while an increase in the amount of moisture leads to heavier snowfalls. This means that warming causes an increase in nutrition and an increase in glaciation in Antarctica.

Last Maximum Glaciation

The culmination of the last ice age on Earth was 21-17 thousand years ago, when the volume of ice increased to approximately 100 million km 3. In Antarctica, glaciation at this time covered the entire continental shelf. The volume of ice in the ice sheet apparently reached 40 million km 3, that is, it was approximately 40% more than its modern volume. The pack ice boundary shifted northward by approximately 10°. In the Northern Hemisphere, 20 thousand years ago, a gigantic Pan-Arctic ancient ice sheet was formed, uniting the Eurasian, Greenland, Laurentian and a number of smaller shields, as well as extensive floating ice shelves. The total volume of the shield exceeded 50 million km 3, and the level of the World Ocean dropped by no less than 125 m.

The degradation of the Panarctic cover began 17 thousand years ago with the destruction of the ice shelves that were part of it. After this, the “marine” parts of the Eurasian and North American ice sheets, which had lost stability, began to collapse catastrophically. The collapse of glaciation occurred in just a few thousand years. At that time, huge masses of water flowed from the edge of the ice sheets, giant dammed lakes arose, and their breakthroughs were many times larger than today. Natural processes dominated in nature, immeasurably more active than now. This led to a significant renewal of the natural environment, a partial change in the animal and plant world, and the beginning of human domination on Earth.

12 thousand years ago, the Holocene began - the modern geological era. Air temperature in temperate latitudes increased by 6° compared to the cold late Pleistocene. Glaciation has assumed modern proportions.

Ancient glaciations...

Ideas about ancient glaciations of mountains were expressed at the end of the 18th century, and about past glaciations of the plains of temperate latitudes - in the first half of the 19th century. The theory of ancient glaciation did not immediately gain recognition among scientists. Even at the beginning of the 19th century, streaked boulders of rocks that were clearly not of local origin were found in many places around the globe, but scientists did not know what could have brought them. IN

In 1830, the English explorer Charles Lyell came up with his theory, in which he attributed both the spreading of boulders and the shading of rocks to the action of floating sea ice. Lyell's hypothesis met with serious objections. During his famous voyage on the Beagle ship (1831-1835), Charles Darwin lived for some time on Tierra del Fuego, where he saw with his own eyes the glaciers and the icebergs they generate. He subsequently wrote that boulders can be carried across the sea by icebergs, especially during periods of greater glacial development. And after his trip to the Alps in 1857, Lyell himself doubted the correctness of his theory. In 1837, the Swiss explorer L. Agassiz was the first to explain the polishing of rocks, the transport of boulders, and the deposition of moraine by the influence of glaciers. A significant contribution to the development of the glacial theory was made by Russian scientists, and above all P.A. Kropotkin. Traveling in Siberia in 1866, he discovered many boulders, glacial sediments, and smooth polished rocks on the Patom Highlands and connected these finds with the activity of ancient glaciers. In 1871, the Russian Geographical Society sent him to Finland, a country with clear traces of recently retreated glaciers. This trip finally shaped his views. When studying ancient geological deposits, we often find tillites - coarse fossilized moraines and glacial-marine sediments. They were found on all continents in sediments of different ages, and they are used to reconstruct the glacial history of the Earth for 2.5 billion years, during which the planet experienced 4 glacial eras that lasted from many tens to 200 million years. Each such era consisted of ice ages comparable in duration to the Pleistocene, or Quaternary period, and each period consisted of a large number of ice ages.

The duration of glacial eras on Earth is at least a third of the total time of its evolution over the past 2.5 billion years. And if we take into account the long initial phases of the origin of glaciation and its gradual degradation, then the glaciation eras will take almost as much time as warm, ice-free conditions. The last of the ice ages began almost a million years ago, in Quaternary time, and was marked by the extensive spread of glaciers - the Great Glaciation of the Earth. The northern part of the North American continent, a significant part of Europe, and possibly also Siberia were under thick covers of ice. In the Southern Hemisphere, the entire Antarctic continent was under ice, as it is now. During the period of maximum expansion of the Quaternary glaciation, glaciers covered over 40 million km 2 - about a quarter of the entire surface of the continents. The largest in the Northern Hemisphere was the North American ice sheet, reaching a thickness of 3.5 km. All of northern Europe was under an ice sheet up to 2.5 km thick. Having reached their greatest development 250 thousand years ago, the Quaternary glaciers of the Northern Hemisphere began to gradually shrink. Glaciation was not continuous throughout the Quaternary period. There is geological, paleobotanical and other evidence that during this time glaciers completely disappeared at least three times, giving way to interglacial eras when the climate was warmer than today. However, these warm eras were replaced by cold snaps, and the glaciers spread again. We now live, apparently, at the end of the fourth epoch of the Quaternary glaciation. The Quaternary glaciation of Antarctica developed quite differently than in the Northern Hemisphere. It arose many millions of years before glaciers appeared in North America and Europe. In addition to the climatic conditions, this was facilitated by the high continent that had existed here for a long time. Unlike the ancient ice sheets of the Northern Hemisphere, which disappeared and then reappeared, the Antarctic ice sheet has changed little in its size. The maximum glaciation of Antarctica was only one and a half times greater in volume than the modern one and not much larger in area.

...and their possible causes

The cause of major climate changes and the occurrence of the great glaciations of the Earth still remains a mystery. All hypotheses expressed on this subject can be combined into three groups - the cause of periodic changes in the earth's climate was sought either outside the solar system, or in the activity of the Sun itself, or in processes occurring on Earth.

Galaxy
Cosmic hypotheses include assumptions about the influence on the cooling of the Earth of various parts of the Universe that the Earth passes through, moving in space along with the Galaxy. Some believe that cooling occurs when the Earth passes through areas of global space filled with gas. Others attribute the same effects to the effects of clouds of cosmic dust. According to another hypothesis, the Earth as a whole should experience great changes when, moving along with the Sun, it moves from the star-saturated part of the Galaxy to its outer, rarefied regions. When the globe approaches the apogalactium - the point furthest from the part of our Galaxy where the largest number of stars are located, it enters the “cosmic winter” zone and the ice age begins.

Sun
The development of glaciations is also associated with fluctuations in the activity of the Sun itself. Heliophysicists have long figured out the periodicity of the appearance of dark spots, flares, and prominences on it and have learned to predict these phenomena. It turned out that solar activity changes periodically. There are periods of different durations: 2-3, 5-6, 11, 22 and about 100 years. It may happen that the culminations of several periods of different durations coincide and solar activity will be especially high. But it may also be the other way around - several periods of reduced solar activity will coincide, and this will cause the development of glaciation. Such changes in solar activity, of course, are reflected in the fluctuations of glaciers, but are unlikely to cause a great glaciation of the Earth.

CO 2
An increase or decrease in temperature on Earth can also occur if the composition of the atmosphere changes. Thus, carbon dioxide, which freely transmits the sun's rays to the Earth, but absorbs most of its thermal radiation, serves as a colossal screen that prevents the cooling of our planet. Now the content of CO 2 in the atmosphere does not exceed 0.03%. If this figure is halved, then average annual temperatures in temperate zones will decrease by 4-5°, which could lead to the onset of an ice age.

Volcanoes
Volcanic dust emitted during large eruptions up to a height of 40 km can also serve as unique screens. Clouds of volcanic dust, on the one hand, block the sun's rays, and on the other hand, do not allow the earth's radiation to pass through. But the first process is stronger than the second, so periods of increased volcanism should cause the Earth to cool.

Mountains
The idea of ​​a connection between glaciation on our planet and mountain building is also widely known. During the eras of mountain building, the rising large masses of the continents fell into higher layers of the atmosphere, cooled and served as places for the birth of glaciers.

Ocean
According to many researchers, glaciation can also occur as a result of a change in the direction of sea currents. For example, the Gulf Stream was previously diverted by a ridge of land extending from Newfoundland to the Cape Verde Islands, helping to cool the Arctic compared to modern conditions.

Atmosphere
Recently, scientists have begun to associate the development of glaciation with a restructuring of atmospheric circulation - when certain areas of the planet receive significantly more precipitation and, in the presence of sufficiently high mountains, glaciation occurs here.

Antarctica
Perhaps the rise of the Antarctic continent contributed to the emergence of glaciation. As a result of the expansion of the Antarctic ice sheet, the temperature of the entire Earth decreased by several degrees and the level of the World Ocean dropped by several tens of meters, which contributed to the development of glaciation in the north.

"Recent History"

The last retreat of glaciers, which began over 10 thousand years ago, remains in human memory. In the historical era - for about 3 thousand years - the advance of glaciers occurred in centuries with lower air temperatures and increased humidity. The same conditions developed in the last centuries of the last era and in the middle of the last millennium. About 2.5 thousand years ago, a significant cooling of the climate began. The Arctic islands were covered with glaciers; in the Mediterranean and Black Sea countries, on the verge of a new era, the climate was colder and wetter than it is now. In the Alps in the 1st millennium BC. e. glaciers moved to lower levels, blocked mountain passes with ice and destroyed some high-lying villages. This era saw a major advance of the Caucasian glaciers. The climate was completely different at the turn of the 1st and 2nd millennia.

Warmer conditions and the absence of ice in the northern seas allowed northern European sailors to penetrate far to the north. In 870, the colonization of Iceland began, where there were fewer glaciers at that time than now.

In the 10th century, the Normans, led by Eirik the Red, discovered the southern tip of a huge island, the shores of which were overgrown with thick grass and tall bushes. They founded the first European colony here, and called this land Greenland.

By the end of the 1st millennium, mountain glaciers in the Alps, the Caucasus, Scandinavia and Iceland had also retreated significantly. The climate began to change seriously again in the 14th century. Glaciers began to advance in Greenland, summer thawing of soil became increasingly short-lived, and by the end of the century permafrost was firmly established here. The ice cover of the northern seas increased, and attempts made in subsequent centuries to reach Greenland usually ended in failure. Since the end of the 15th century, the advance of glaciers began in many mountainous countries and polar regions. After the relatively warm 16th century, harsh centuries began, called the Little Ice Age. In the south of Europe, severe and long winters often recurred; in 1621 and 1669, the Bosporus Strait froze, and in 1709, the Adriatic Sea froze off the coast. In the second half of the 19th century, the Little Ice Age ended and a relatively warm era began, which continues to this day.

What awaits us?

The warming of the 20th century was especially pronounced in the polar latitudes of the Northern Hemisphere. Fluctuations in glacial systems are characterized by the proportion of advancing, stationary, and retreating glaciers. For example, for the Alps there is data covering the entire past century. If the share of advancing alpine glaciers in the 40-50s was close to zero, then in the mid-60s about 30%, and in the late 70s - 65-70% of the surveyed glaciers, advanced here. Their similar state indicated that the anthropogenic increase in the content of carbon dioxide, other gases and aerosols in the atmosphere in the 20th century did not affect the normal course of global atmospheric and glacial processes. However, at the end of the last century, glaciers throughout the mountains began to retreat, which was a reaction to global warming, the trend of which especially intensified in the 1990s.

It is known that the currently increased amount of aerosol emissions of anthropogenic origin into the atmosphere helps to reduce the influx of solar radiation. In this regard, voices appeared about the beginning of the Ice Age, but they were lost in a powerful wave of fears of impending anthropogenic warming due to the constant increase in CO 2 and other gaseous impurities in the atmosphere.

An increase in CO2 leads to an increase in the amount of retained heat and thereby increases the temperature. Some small gas impurities entering the atmosphere have the same effect: freons, nitrogen oxides, methane, ammonia, and so on. But nevertheless, not the entire mass of carbon dioxide formed during combustion remains in the atmosphere: 50-60% of industrial CO 2 emissions end up in the ocean or are absorbed by plants. A multiple increase in the concentration of CO 2 in the atmosphere does not lead to the same multiple increase in temperature. Obviously, there is a natural regulation mechanism that sharply slows down the greenhouse effect at CO 2 concentrations exceeding two or three times.

It is difficult to say with certainty what the prospects for an increase in the CO2 content in the atmosphere are in the coming decades and how the temperature will rise as a result of this. Some scientists suggest its increase in the first quarter of the 21st century by 1-1.5°, and in the future even more. However, this position has not been proven; there are many reasons to believe that modern warming is part of a natural cycle of climate fluctuations and will be replaced by cooling in the near future. In any case, the Holocene, which has lasted for more than 11 thousand years, turns out to be the longest interglacial in the last 420 thousand years and will obviously end soon. And while we are concerned about the consequences of the current warming, we must not forget about the possible future cooling on Earth.

Vladimir Kotlyakov, academician, director of the Institute of Geography of the Russian Academy of Sciences

State educational institution of higher professional education of the Moscow region

International University of Nature, Society and Human "Dubna"

Faculty of Science and Engineering

Department of Ecology and Geosciences

COURSE WORK

By discipline

Geology

Scientific supervisor:

Ph.D., Associate Professor Anisimova O.V.

Dubna, 2011

Introduction

1. Ice Age

1.1 Ice ages in the history of the Earth

1.2 Proterozoic Ice Age

1.3 Paleozoic Ice Age

1.4 Cenozoic Ice Age

1.5 Tertiary period

1.6 Quaternary period

2. Last Ice Age

2.2 Flora and fauna

2.3Rivers and lakes

2.4West Siberian Lake

2.5The world's oceans

2.6 Great Glacier

3. Quaternary glaciations in the European part of Russia

4. Causes of Ice Ages

Conclusion

References

Introduction

Target:

Explore the major glacial epochs in Earth's history and their role in shaping the modern landscape.

Relevance:

The relevance and significance of this topic is determined by the fact that the ice ages are not so well studied to fully confirm their existence on our Earth.

Tasks:

– conduct a literature review;

– establish the main glacial epochs;

– obtaining detailed data on the last Quaternary glaciations;

Establish the main causes of glaciations in the history of the Earth.

At present, little data has been obtained that confirms the distribution of frozen rock layers on our planet in ancient eras. The evidence is mainly the discovery of ancient continental glaciations from their moraine deposits and the establishment of the phenomena of mechanical detachment of glacier bed rocks, the transfer and processing of clastic material and its deposition after the melting of the ice. Compacted and cemented ancient moraines, the density of which is close to rocks such as sandstones, are called tillites. The discovery of such formations of different ages in different regions of the globe clearly indicates the repeated appearance, existence and disappearance of ice sheets, and, consequently, frozen strata. The development of ice sheets and frozen strata can occur asynchronously, i.e. The maximum development of the area of ​​glaciation and the permafrost zone may not coincide in phase. However, in any case, the presence of large ice sheets indicates the existence and development of frozen strata, which should occupy much larger areas in area than the ice sheets themselves.

According to N.M. Chumakov, as well as V.B. Harland and M.J. Hambry, the time intervals during which glacial deposits were formed are called glacial eras (lasting the first hundreds of millions of years), ice ages (millions - first tens of millions of years), glacial epochs (first millions of years). In the history of the Earth, the following glacial eras can be distinguished: Early Proterozoic, Late Proterozoic, Paleozoic and Cenozoic.

1. Ice Age

Are there ice ages? Of course yes. The evidence for this is incomplete, but it is quite definite, and some of this evidence extends over large areas. Evidence of the Permian Ice Age is present on several continents, and in addition, traces of glaciers have been found on the continents dating back to other eras of the Paleozoic era up to its beginning, Early Cambrian time. Even in much older rocks, formed before the Phanerozoic, we find traces left by glaciers and glacial deposits. Some of these tracks are more than two billion years old, possibly half the age of Earth as a planet.

The ice age of glaciations (glacials) is a period of time in the geological history of the Earth, characterized by a strong cooling of the climate and the development of extensive continental ice not only in the polar, but also in temperate latitudes.

Peculiarities:

·It is characterized by long-term, continuous and severe climate cooling, the growth of ice caps in polar and temperate latitudes.

· Ice ages are accompanied by a decrease in the level of the World Ocean by 100 m or more, due to the fact that water accumulates in the form of ice sheets on land.

·During ice ages, areas occupied by permafrost expand, and soil and plant zones shift towards the equator.

It has been established that over the past 800 thousand years there have been eight ice ages, each of which lasted from 70 to 90 thousand years.

Fig.1 Ice Age

1.1 Ice ages in the history of the Earth

Periods of climate cooling, accompanied by the formation of continental ice sheets, are recurring events in the history of the Earth. Intervals of cold climate during which extensive continental ice sheets and sediments are formed, lasting hundreds of millions of years, are called glacial eras; In glacial eras, ice ages lasting tens of millions of years are distinguished, which, in turn, consist of ice ages - glaciations (glacials), alternating with interglacials (interglacials).

Geological studies have proven that there was a periodic process of climate change on Earth, spanning the time from the late Proterozoic to the present.

These are relatively long glacial eras that lasted for almost half of the Earth's history. The following glacial eras are distinguished in the history of the Earth:

Early Proterozoic - 2.5-2 billion years ago

Late Proterozoic - 900-630 million years ago

Paleozoic - 460-230 million years ago

Cenozoic - 30 million years ago - present

Let's take a closer look at each of them.

1.2 Proterozoic Ice Age

Proterozoic - from the Greek. the words protheros - primary, zoe - life. The Proterozoic era is a geological period in the history of the Earth, including the history of the formation of rocks of various origins from 2.6 to 1.6 billion years. A period in the history of the Earth that was characterized by the development of the simplest life forms of single-celled living organisms from prokaryotes to eukaryotes, which later, as a result of the so-called Ediacaran “explosion,” evolved into multicellular organisms.

Early Proterozoic glacial era

This is the oldest glaciation recorded in geological history, which appeared at the end of the Proterozoic on the border with the Vendian and, according to the Snowball Earth hypothesis, the glacier covered most of the continents at equatorial latitudes. In fact, it was not one, but a series of glaciations and interglacial periods. Since it is believed that nothing can prevent the spread of glaciation due to an increase in albedo (reflection of solar radiation from the white surface of glaciers), it is believed that the cause of subsequent warming may be, for example, an increase in the amount of greenhouse gases in the atmosphere due to increased volcanic activity , accompanied, as is known, by emissions of huge amounts of gases.

Late Proterozoic glacial era

Identified under the name of the Lapland glaciation at the level of Vendian glacial deposits 670-630 million years ago. These deposits are found in Europe, Asia, West Africa, Greenland and Australia. Paleoclimatic reconstruction of glacial formations from this time suggests that the European and African ice continents of that time were a single ice sheet.

Fig.2 Vend. Ulytau during the Ice Age Snowball

1.3 Paleozoic Ice Age

Paleozoic - from the word paleos - ancient, zoe - life. Palaeozoic. Geological time in the history of the Earth covering 320-325 million years. With an age of glacial deposits of 460 - 230 million years, it includes the Late Ordovician - Early Silurian (460-420 million years), Late Devonian (370-355 million years) and Carboniferous-Permian glacial periods (275 - 230 million years). The interglacial periods of these periods are characterized by a warm climate, which contributed to the rapid development of vegetation. In the places where they spread, large and unique coal basins and horizons of oil and gas fields were later formed.

Late Ordovician - Early Silurian Ice Age.

Glacial deposits of this time, called Saharan (after the name of modern Sahara). They were distributed in the territory of modern Africa, South America, eastern North America and Western Europe. This period is characterized by the formation of an ice sheet over much of northern, northwestern and western Africa, including the Arabian Peninsula. Paleoclimatic reconstructions suggest that the thickness of the Saharan ice sheet reached at least 3 km and was similar in area to the modern glacier of Antarctica.

Late Devonian Ice Age

Glacial deposits from this period were found in the territory of modern Brazil. The glacial area extended from the modern mouth of the river. Amazon to the east coast of Brazil, taking over the Niger region in Africa. In Africa, Northern Niger contains tillites (glacial deposits) that are comparable to those in Brazil. In general, the glacial areas stretched from the border of Peru with Brazil to northern Niger, the diameter of the area was more than 5000 km. The South Pole in the Late Devonian, according to the reconstruction of P. Morel and E. Irving, was located in the center of Gondwana in Central Africa. Glacial basins are located on the oceanic margin of the paleocontinent, mainly in high latitudes (not north of the 65th parallel). Judging by the then high-latitude continental position of Africa, one can assume the possible widespread development of frozen rocks on this continent and, in addition, in the north-west of South America.

Carboniferous-Permian Ice Age

It became widespread in the territory of modern Europe and Asia. During the Carboniferous, there was a gradual cooling of the climate, culminating about 300 million years ago. This was facilitated by the concentration of most of the continents in the southern hemisphere and the formation of the supercontinent Gondwana, the formation of large mountain ranges and changes in ocean currents. During the Carboniferous–Permian, most of Gondwana experienced glacial and periglacial conditions.

The center of the continental ice sheet of Central Africa was located near the Zambezi, from where the ice flowed radially into several African basins and spread to Madagascar, South Africa and parts of South America. With a radius of the ice sheet of approximately 1750 km, according to calculations, the ice thickness could be up to 4 – 4.5 km. In the southern hemisphere, at the end of the Carboniferous–Early Permian, a general uplift of Gondwana occurred and glaciation spread over most of this supercontinent. The Carboniferous-Permian Ice Age lasted at least 100 million years, but there was no single large ice cap. The peak of the Ice Age, when the ice sheets extended far to the north (up to 30° - 35° S), lasted about 40 million years (between 310 - 270 million years ago). According to calculations, the Gondwana glaciation area occupied an area of ​​at least 35 million km 2 (possibly 50 million km 2), which is 2–3 times larger than the area of ​​modern Antarctica. Ice sheets reached 30° – 35°S. The main center of glaciation was the region of the Sea of ​​Okhotsk, which, apparently, was located near the North Pole.

Fig.3 Paleozoic Ice Age

1.4 Cenozoic Ice Age

The Cenozoic Ice Age (30 million years ago - present) is a recently begun glacial era.

The present time - the Holocene, which began ≈ 10,000 years ago, is characterized as a relatively warm interval after the Pleistocene Ice Age, often classified as an interglacial. Ice sheets exist at high latitudes in the northern (Greenland) and southern (Antarctica) hemispheres; Moreover, in the northern hemisphere, the cover glaciation of Greenland extends south to 60° north latitude (i.e., to the latitude of St. Petersburg), fragments of sea ice cover - to 46-43° north latitude (i.e., to the latitude of Crimea) , and permafrost to 52-47° north latitude. In the southern hemisphere, continental Antarctica is covered by an ice sheet 2500-2800 m thick (up to 4800 m in some areas of East Antarctica), with ice shelves accounting for ≈10% of the continent's area above sea level. In the Cenozoic glacial era, the Pleistocene ice age is the strongest: a decrease in temperature led to glaciation of the Arctic Ocean and the northern regions of the Atlantic and Pacific Oceans, while the glaciation boundary ran 1500-1700 km south of the modern one.

Geologists divide the Cenozoic into two periods: Tertiary (65 - 2 million years ago) and Quaternary (2 million years ago - our time), which in turn are divided into epochs. Of these, the first is much longer than the second, but the second - quaternary - has a number of unique features; this is the time of ice ages and the final formation of the modern face of the Earth.

Rice. 4 Cenozoic Ice Age. Ice age. Climate curve for the last 65 million years.

34 million years ago - the birth of the Antarctic ice sheet

25 million years ago - its abbreviation

13 million years ago - its re-growth

About 3 million years ago - the beginning of the Pleistocene Ice Age, repeated appearance and disappearance of ice sheets in the northern regions of the Earth

1.5 Tertiary period

The Tertiary period consists of eras:

·Paleocene

Oligocene

Pliocene

Paleocene era (from 65 to 55 million years ago)

Geography and climate: The Paleocene marked the beginning of the Cenozoic era. At that time, the continents were still in motion as the "great southern continent" Gondwana continued to break apart. South America was now completely cut off from the rest of the world and turned into a kind of floating “ark” with a unique fauna of early mammals. Africa, India and Australia have moved even further away from each other. Throughout the Paleocene, Australia was located near Antarctica. Sea levels have dropped, and new land areas have emerged in many areas of the globe.

Fauna: The age of mammals began on land. Rodents and insectivores appeared. There were also large animals among them, both predators and herbivores. In the seas, marine reptiles were replaced by new species of predatory bony fish and sharks. New varieties of bivalves and foraminifera emerged.

Flora: More and more new species of flowering plants and the insects that pollinate them continued to spread.

Eocene Epoch (from 55 to 38 million years ago)

Geography and climate: During the Eocene, the main land masses began to gradually assume a position close to that which they occupy today. Much of the land was still divided into giant islands of sorts, as the huge continents continued to move away from each other. South America lost contact with Antarctica, and India moved closer to Asia. At the beginning of the Eocene, Antarctica and Australia were still located nearby, but later they began to diverge. North America and Europe also split apart, with new mountain ranges emerging. The sea flooded part of the land. The climate was warm or temperate everywhere. Much of it was covered with lush tropical vegetation, and large areas were covered with dense swamp forests.

Fauna: Bats, lemurs, and tarsiers appeared on land; ancestors of today's elephants, horses, cows, pigs, tapirs, rhinoceroses and deer; other large herbivores. Other mammals, such as whales and sirenians, have returned to the aquatic environment. The number of freshwater bony fish species has increased. Other groups of animals also evolved, including ants and bees, starlings and penguins, giant flightless birds, moles, camels, rabbits and voles, cats, dogs and bears.

Flora: Lush forests grew in many parts of the world, and palm trees grew in temperate latitudes.

Oligocene Epoch (from 38 to 25 million years ago)

Geography and Climate: During the Oligocene era, India crossed the equator and Australia finally separated from Antarctica. The climate on Earth became cooler, and a huge ice sheet formed over the South Pole. To form such a large amount of ice required equally significant volumes of sea water. This led to lower sea levels across the planet and an expansion of land area. Widespread cooling caused the disappearance of lush Eocene tropical forests in many areas of the globe. Their place was taken by forests that preferred a more temperate (cool) climate, as well as vast steppes spread across all continents.

Fauna: With the spread of the steppes, a rapid flourishing of herbivorous mammals began. Among them, new species of rabbits, hares, giant sloths, rhinoceroses and other ungulates arose. The first ruminants appeared.

Flora: Tropical forests decreased in size and began to give way to temperate forests, and vast steppes appeared. New grasses quickly spread, and new types of herbivores developed.

Miocene era (from 25 to 5 million years ago)

Geography and climate: During the Miocene, the continents were still “on the march”, and a number of grandiose cataclysms occurred during their collisions. Africa "crashed" into Europe and Asia, resulting in the appearance of the Alps. When India and Asia collided, the Himalayan mountains rose up. At the same time, the Rocky Mountains and Andes formed as other giant plates continued to shift and slide on top of each other.

However, Austria and South America remained isolated from the rest of the world, and each of these continents continued to develop its own unique fauna and flora. Ice cover in the southern hemisphere has spread throughout Antarctica, causing the climate to cool further.

Fauna: Mammals migrated from continent to continent along newly formed land bridges, which sharply accelerated evolutionary processes. Elephants moved from Africa to Eurasia, and cats, giraffes, pigs and buffaloes moved in the opposite direction. Saber-toothed cats and monkeys, including anthropoids, appeared. In Australia, cut off from the outside world, monotremes and marsupials continued to develop.

Flora: Inland areas became colder and drier, and steppes became more widespread in them.

Pliocene Epoch (from 5 to 2 million years ago)

Geography and climate: A space traveler looking down on the Earth at the beginning of the Pliocene would have found continents in almost the same places as today. A galactic visitor would be able to see the giant ice caps in the northern hemisphere and the huge ice sheet of Antarctica. Because of all this mass of ice, the Earth's climate became even cooler, and the surface of the continents and oceans of our planet became significantly colder. Most of the forests that remained in the Miocene disappeared, giving way to vast steppes that spread throughout the world.

Fauna: Herbivorous ungulate mammals continued to rapidly reproduce and evolve. Towards the end of the period, a land bridge connected South and North America, which led to a huge "exchange" of animals between the two continents. It is believed that increased interspecific competition caused the extinction of many ancient animals. Rats entered Australia, and the first humanoid creatures appeared in Africa.

Flora: As the climate cooled, steppes replaced forests.

Fig.5 Diverse mammals evolved during the Tertiary period

1.6 Quaternary period

Consists of eras:

·Pleistocene

Holocene

Pleistocene era (from 2 to 0.01 million years ago)

Geography and climate: At the beginning of the Pleistocene, most continents occupied the same position as today, and some of them required crossing half the globe to do so. A narrow land bridge connected North and South America. Australia was located on the opposite side of the Earth from Britain. Giant ice sheets were creeping across the northern hemisphere. This was the era of the great glaciation with alternating periods of cooling and warming and fluctuations in sea level. This ice age continues to this day.

Fauna: Some animals managed to adapt to the increased cold by acquiring thick fur: for example, woolly mammoths and rhinoceroses. The most common predators are saber-toothed cats and cave lions. This was the age of giant marsupials in Australia and huge flightless birds, such as moas and apiornis, that lived in many areas of the southern hemisphere. The first people appeared, and many large mammals began to disappear from the face of the Earth.

Flora: Ice gradually crawled from the poles, and coniferous forests gave way to the tundra. Further from the edge of the glaciers, deciduous forests were replaced by coniferous ones. In the warmer regions of the globe there are vast steppes.

Holocene era (from 0.01 million years to the present day)

Geography and climate: The Holocene began 10,000 years ago. Throughout the Holocene, the continents occupied almost the same places as they do today; the climate was also similar to the modern one, becoming warmer and colder every few millennia. Today we are experiencing one of the warming periods. As the ice sheets thinned, sea levels slowly rose. The time of the human race began.

Fauna: At the beginning of the period, many animal species became extinct, mainly due to general climate warming, but increased human hunting for them may also have had an impact. Later they could fall victim to competition from new species of animals brought by people from other places. Human civilization has become more developed and spread throughout the world.

Flora: With the advent of agriculture, peasants destroyed more and more wild plants in order to clear areas for crops and pastures. In addition, plants brought by people to new areas sometimes replaced indigenous vegetation.

Rice. 6 Proboscis, the largest land animals of the Quaternary period

glacial era tertiary quaternary

2. Last Ice Age

The last ice age (last glaciation) is the last of the ice ages within the Pleistocene or Quaternary ice age. It began about 110 thousand years ago and ended around 9700-9600 BC. e. For Siberia it is usually called “Zyryanskaya”, in the Alps - “Würmskaya”, in North America - “Wisconsinskaya”. During this era, the expansion and contraction of ice sheets occurred repeatedly. The Last Glacial Maximum, when the total volume of ice in glaciers was greatest, dates back to about 26-20 thousand years ago of individual ice sheets.

At this time, the polar glaciers of the northern hemisphere grew to enormous sizes, uniting into a huge ice sheet. Long tongues of ice extended from it to the south along the beds of large rivers. All the high mountains were also covered in ice. Cooling and the formation of glaciers led to other global changes in nature. Rivers flowing into the northern seas turned out to be dammed by ice walls, they spilled into giant lakes and turned back trying to find a drain in the south. Heat-loving plants moved south, giving way to more cold-tolerant neighbors. At this time, the mammoth faunal complex was finally formed, consisting mainly of large animals well protected from the cold.

2.1 Climate

However, during the last glaciation, the climate on the planet was not constant. Climate warming periodically occurred, the glacier melted along the edge, retreated to the north, the areas of high-mountain ice decreased, and climatic zones shifted south. There have been several such minor changes in climate. Scientists believe that the coldest and most severe period in Eurasia was about 20 thousand years ago.

Rice. 7 Perito Moreno Glacier in Patagonia, Argentina. during the last ice age

Rice. 8 The diagram shows climate changes in Siberia and some other areas of the northern hemisphere over the past 50 thousand years

2.2 Flora and fauna

The cooling of the planet and the formation of giant glacial systems in the north caused global changes in the flora and fauna of the Northern Hemisphere. The boundaries of all natural zones began to shift south. The following natural zones were located on the territory of Siberia.

Along the glaciers, a zone of cold tundras and tundra-steppes stretches tens of kilometers wide. It was located approximately in the areas where there is now forest and taiga.

In the south, the tundra-steppe gradually turned into forest-steppe and forests. Forest areas were very small, and were not everywhere. Most often, forests were located on the southern shores of periglacial lakes and in river valleys and on mountain spurs.

Even further south were dry steppes, in the west of Siberia gradually turning into the Sayan-Altai mountain systems, in the east bordering on the semi-deserts of Mongolia. In some areas, the tundra-steppe and steppe were not separated by a strip of forest, but gradually replaced each other.

Fig.9. Tundra-steppe, the era of the last glaciation

In the new climatic conditions of the Ice Age, the animal world also changed. During the last stages of the Quaternary period, new species of fauna were formed in the Northern Hemisphere. A particularly expressive manifestation of these changes was the appearance of the so-called mammoth faunal complex, which consisted of cold-tolerant animal species.

2.3 Rivers and lakes

Giant ice fields formed a natural dam and blocked the flow of rivers flowing into the Northern Seas. Modern Siberian rivers: the Ob, Irtysh, Yenisei, Lena, Kolyma and many others overflowed along the glaciers, forming giant lakes that were combined into periglacial meltwater drainage systems.

Siberia in the Ice Age. For clarity, modern rivers and cities are indicated. Most of this system was connected by rivers and water flowed out of it to the southwest through the system of the New Euxine basin, which was once on the site of the Black Sea. Further, through the Bosphorus and Dardanelles, the water entered the Mediterranean Sea. The total area of ​​this drainage basin was 22 million square meters. km. It served the territory from Mongolia to the Mediterranean.

Fig. 10 Siberia during the Ice Age

In North America, there was also such a system of periglacial lakes. Along the Laurentian ice sheet stretched the now disappeared giant Lake Agassiz, Lake McConnell and Lake Algonque.

2.4 West Siberian Lake

Some scientists believe that one of the largest periglacial lakes in Eurasia was Mansiyskoe, or as it is also called West Siberian Lake. It occupied almost the entire territory of the West Siberian Plain to the foothills of the Kuznetsk Alatau and Altai. The places where the largest cities of Tyumen, Tomsk and Novosibirsk are now located were covered with water during the last ice age. When the glacier began to melt - 16-14 thousand years ago, the waters of Lake Mansi began to gradually flow into the Arctic Ocean, and in its place modern river systems were formed, and in the lowland part of the Taiga Ob region, the largest system of Vasyugan Swamps in Eurasia was formed.

Fig. 11 This is what West Siberian Lake looked like

2.5 Oceans

The planet's ice sheets are formed by the waters of the world's oceans. Accordingly, the larger and higher the glaciers, the less water remains in the ocean. Glaciers absorb water, the ocean level drops, exposing large areas of land. Thus, 50,000 years ago, due to the growth of glaciers, the sea level dropped by 50 m, and 20,000 years ago - by 110-130 m. During this period, many modern islands formed a single whole with the mainland. Thus, the British, Japanese, and New Siberian Islands were inseparable from the mainland. In place of the Bering Strait there was a wide strip of land called Beringia.

Fig. 12 Diagram of sea level changes during the last ice age

2.6 Great Glacier

During the last glaciation, the planet's subpolar part of the Northern Hemisphere was occupied by a huge Arctic ice sheet. It was formed as a result of the merger of the North American and Eurasian ice sheets into a single system.

The Arctic ice sheet consisted of giant ice sheets shaped like flat-convex domes, which formed ice layers 2-3 kilometers high in some places. The total area of ​​ice cover is more than 40 million square meters. km.

The largest elements of the Arctic Ice Sheet:

1. Laurentian shield centered over southwestern Hudson Bay;

2. The Kara shield, centered over the Kara Sea, extended to the entire north of the Russian Plain, Western and Central Siberia;

3. Greenland shield;

4. East Siberian shield, covering the Siberian seas, the coast of Eastern Siberia and part of Chukotka;

5. Icelandic shield

Rice. 13 Arctic ice sheet

Even during the harsh Ice Age, the climate was constantly changing. The glaciers gradually advanced south and then retreated again. The ice sheet reached its maximum thickness about 20,000 years ago.

3. Quaternary glaciations in the European part of Russia

Quaternary glaciation - glaciation in the Quaternary period, caused by a decrease in temperature that began at the end of the Neogene period. In the mountains of Europe, Asia, and America, glaciers began to increase, flowing onto the plains; on the Scandinavian Peninsula, a gradually expanding ice cap formed; the advancing ice pushed the animals and plants that lived there to the south.

The thickness of the ice cover reached 2 - 3 kilometers. About 30% of the territory of modern Russia in the north was occupied by sheet glaciation, which either decreased slightly, then moved south again. Interglacial periods with warm, mild climates were followed by cold snaps when the glaciers advanced again.

On the territory of modern Russia there were 4 glaciations - Oka, Dnieper, Moscow and Valdai. The largest of them was the Dnieper, when a giant glacial tongue descended along the Dnieper to the latitude of Dnepropetrovsk, and along the Don to the mouth of the Medveditsa.

Consider the Moscow glaciation

The Moscow glaciation is an ice age dating back to the Anthropogen (Quaternary) period (Middle Pleistocene, about 125-170 thousand years ago), the last of the major glaciations of the Russian (East European) Plain.

It was preceded by the Odintsovo time (170-125 thousand years ago) - a relatively warm period separating the Moscow glaciation from the maximum, Dnieper glaciation (230-100 thousand years ago), also in the Middle Pleistocene.

The Moscow glaciation was identified as an independent ice age relatively recently. Some researchers still interpret the Moscow glaciation as one of the stages of the Dnieper glaciation, or that it was one of the stages of a larger and longer previous glaciation. However, the boundary of the glacier developing during the Muscovite era is drawn with greater validity.

Moscow glaciation only captured the northern part of the Moscow region. The glacier's border ran along the Klyazma River. It was during the melting of the Moscow glacier that the morainic strata of the Dnieper glaciation were almost completely washed away. The watering of the periglacial zone, which directly included the territory of the Shatura region, during the melting of the Moscow glacier was so great that the lowlands were filled with large lakes or turned into powerful valleys of runoff of melted glacial waters. Suspensions settled in them, forming outwash plains with sandy and sandy loam deposits, which are most common within the region at present.

Fig. 14 Position of terminal glacial moraines of different ages within the central part of the Russian Plain. Moraine of the Early Valdai () and Late Valdai () glaciations.

4. Causes of Ice Ages

The causes of the Ice Ages are inextricably linked to the broader issues of global climate change that have occurred throughout Earth's history. From time to time, significant changes in geological and biological conditions occurred. It should be borne in mind that the beginning of all great glaciations is determined by two important factors.

First, over thousands of years, the annual precipitation pattern should be dominated by heavy, long-lasting snowfalls.

Secondly, in areas with such a precipitation regime, temperatures must be so low that summer snowmelt is minimized and firn fields increase year after year until glaciers begin to form. Abundant snow accumulation must dominate the glacier balance throughout the glaciation, since if ablation exceeds accumulation, glaciation will decline. Obviously, for each ice age it is necessary to find out the reasons for its beginning and end.

Hypotheses

1. The pole migration hypothesis. Many scientists believed that the Earth's rotation axis changes its position from time to time, which leads to a corresponding shift in climate zones.

2. Carbon dioxide hypothesis. Carbon dioxide CO2 in the atmosphere acts like a warm blanket to trap the heat emitted by the Earth near its surface, and any significant reduction in CO2 in the air will result in a drop in temperature on Earth. As a result, the temperature of the land will drop, and the Ice Age will begin.

3. Hypothesis of diastrophism (movements of the earth's crust). Significant uplifts of land have repeatedly occurred in the history of the Earth. In general, the air temperature over land decreases by about 1.8. With a rise of every 90 m. In fact, the mountains rose many hundreds of meters, which turned out to be sufficient for the formation of valley glaciers there. In addition, the growth of mountains changes the circulation of moisture-carrying air masses. Rising areas of the ocean floor can in turn change the circulation of ocean waters and also cause climate change. It is not known whether tectonic movements alone could have been the cause of glaciation, in any case, they could greatly contribute to its development

4. Volcanic dust hypothesis. Volcanic eruptions are accompanied by the release of huge amounts of dust into the atmosphere. It is obvious that volcanic activity, widespread on Earth for thousands of years, could significantly lower air temperatures and cause the onset of glaciation.

5. Continental drift hypothesis. According to this hypothesis, all modern continents and the largest islands were once part of the single continent of Pangea, washed by the World Ocean. The consolidation of continents into such a single landmass could explain the development of the Late Paleozoic glaciation of South America, Africa, India and Australia. The areas covered by this glaciation were probably much further north or south than their present position. The continents began to separate in the Cretaceous, and reached their present position approximately 10 thousand years ago

6. Ewing-Donna conjecture. One of the attempts to explain the reasons for the emergence of the Pleistocene Ice Age belongs to M. Ewing and W. Donne, geophysicists who made a significant contribution to the study of the topography of the ocean floor. They believe that in pre-Pleistocene times the Pacific Ocean occupied the northern polar regions and therefore it was much warmer there than now. The Arctic land areas were then located in the North Pacific Ocean. Then, as a result of continental drift, North America, Siberia and the Arctic Ocean took their modern position. Thanks to the Gulf Stream coming from the Atlantic, the waters of the Arctic Ocean at that time were warm and evaporated intensively, which contributed to heavy snowfalls in North America, Europe and Siberia. Thus, the Pleistocene glaciation began in these areas. It stopped because, as a result of the growth of glaciers, the level of the World Ocean dropped by about 90 m, and the Gulf Stream was eventually unable to overcome the high underwater ridges separating the basins of the Arctic and Atlantic oceans. Deprived of the influx of warm Atlantic waters, the Arctic Ocean froze, and the source of moisture feeding the glaciers dried up.

7. Hypothesis of circulation of ocean waters. There are many currents in the oceans, both warm and cold, which have a significant impact on the climate of the continents. The Gulf Stream is one of the remarkable warm currents that washes the northern coast of South America, passes through the Caribbean Sea and the Gulf of Mexico and crosses the North Atlantic, having a warming effect on Western Europe. Warm currents also exist in the South Pacific and Indian Ocean. The most powerful cold currents are directed from the Arctic Ocean to the Pacific Ocean through the Bering Strait and to the Atlantic Ocean through the straits along the eastern and western coasts of Greenland. One of them, the Labrador Current, cools the New England coast and brings fogs there. Cold waters also enter the southern oceans from Antarctica in the form of particularly powerful currents moving north almost to the equator along the western coasts of Chile and Peru. The strong subsurface Gulf Stream carries its cold waters south into the North Atlantic.

8. Hypothesis of changes in solar radiation. As a result of a long-term study of sunspots, which are strong plasma emissions in the solar atmosphere, it was discovered that there are very significant annual and longer cycles of changes in solar radiation. Peaks in solar activity occur approximately every 11, 33, and 99 years, when the Sun emits more heat, resulting in a more powerful circulation of the Earth's atmosphere, accompanied by greater cloudiness and heavier precipitation. Due to high clouds blocking the sun's rays, the land surface receives less heat than usual.

Conclusion

During the course work, glacial eras, which include ice ages, were studied. Ice ages have been identified and analyzed with precision. Detailed data on the last ice age has been obtained. The last Quaternary epochs have been identified. The main causes of ice ages have also been studied.

References

1. Dotsenko S.B. On the glaciation of the Earth at the end of the Paleozoic // Life of the Earth. Geodynamics and mineral resources. M.: Moscow State University Publishing House, 1988.

2. Serebryanny L.R. Ancient glaciation and life / Serebryanny Leonid Ruvimovich; Responsible editor G.A. Avsyuk. - M.: Nauka, 1980. - 128 p.: ill. - (Man and the environment). - Bibliography

3. Secrets of the Ice Ages: Trans. from English/Ed. G.A. Avsyuka; Afterword G.A. Avsyuk and M.G. Grosvalda.-M.: Progress, 1988.-264 p.

4. http://ru.wikipedia.org/wiki/Ice_age (Material from Wikipedia - the free encyclopedia)

5. http://www.ecology.dubna.ru/dubna/pru/geology.html (Article Geological and geomorphological features. N.V. Koronovsky)

6. http://ru.wikipedia.org/wiki/Ice_age (Material from Wikipedia - the free encyclopedia)

7. http://www.fio.vrn.ru/2004/7/kaynozoyskaya.htm (Cenozoic era)