For what reasons was a glacier formed in Antarctica? Formation of the glacial shell of Antarctica. Scientists: New mountain range will grow in India

​Specialists from the US National Aeronautics and Space Administration (NASA) have found the cause of the melting of Antarctic ice, writes The Independent. Researchers believe that the source of heat that melts the ice shell at the South Pole of the Earth may be a mantle plume hiding under the ice (a hot lava flow that can break through the earth's crust and burst to the surface, forming a volcano - editor's note). The temperature of the earth's crust above it rises, which leads to melting, cracking and destruction of glaciers.

About 30 years ago, a scientist from the University of Colorado put forward a hypothesis about the existence of such a plume under the Mary Byrd Land region in West Antarctica. But only recently was it possible to find confirmation of his assumption. NASA specialists were able to verify the veracity of this theory.

For this, experts have developed a special mathematical model. Calculations have shown how much geothermal energy is required for the processes occurring in the Mary Baird Land, including the appearance of the underground rivers and lakes that exist there. Having compared the theoretical model with data obtained during Antarctic expeditions, scientists came to the conclusion that beneath the surface there really is a mantle plume that formed 50-110 million years ago - long before the formation of the ice sheet on the continent.

As New Day wrote, the cause of the melting of glaciers in Greenland is also a mantle plume. The study was carried out by an international group of scientists, with the direct participation of employees of the Novosibirsk State University (NSU) and the Institute of Petroleum Geology and Geophysics () SB RAS. Scientists have linked the current decrease in the volume of ice cover with events 80-35 million years ago, when land, which later became known as Greenland, began to rise above the ocean. It was then that the so-called ancient mantle plume originated.

Scientists have discovered meltwater under the glaciers of Greenland. Previously, it was believed that glaciers melt only in the coastal part of the island, but in 2001, in its depths, between rock and ice, they found a layer of liquid water. Due to the fact that the thickness of the glaciers here reaches 3 thousand meters, and there are no above-zero temperatures at all, there should be no melt water that forms subglacial rivers and lakes.

Researchers are confident that the melting of ice is facilitated by a plume, the main part of which is now located under Iceland, and it is called “Icelandic”. It is well known to geologists and, as it turned out, tens of millions of years ago Greenland actually “floated” over it. After calculating the theoretical heat flow that a plume could cause, it turned out that it was quite enough to melt the lower part of the glacier.

“This work provided geophysical evidence that the Icelandic plume left a mark on the island's lithosphere. Thus, the decrease in the mass of Greenland glaciers is influenced not only by rapid climate variations on Earth, but also by echoes of large-scale events that occurred tens of millions of years ago,” said one of the study participants, head of the NSU laboratories and professor Ivana Kulakova. The results of the study were published in the prestigious journal Nature Geoscience.

As Lenta.ru reminds, in October, a massif with an area four times larger than Manhattan Island broke away from one of the two largest glaciers in Antarctica, Pine Island. According to a forecast made on the basis of satellite images of glaciers, in the future the process of melting ice will accelerate two to three times, increasing the level of the World Ocean. In July, one of the largest icebergs on record broke off from the Larsen Ice Shelf in Antarctica. Its area was 5800 square kilometers.

Washington, Ivan Gridin

Were there any great catastrophes?
Primitive organisms became more complex until, through a long line of ancestors, man finally arose. Gradually, the gaps in the geological record were filled, and the harmonious picture of the development of the Earth was already close to completion. It seemed that the prediction of the founder of scientific geology, Charles Lyell, made back in 1830, was coming true: “The order in nature, from the earliest periods, was monotonous in the sense in which we consider it monotonous now, and we hope that it will remain so and for the future."
And yet there were disasters!
Signs of dramatic changes were observed simultaneously throughout the entire Earth. Over the past billion years, four great catastrophes have been of greatest importance - 650, 230, 65 and 35 million years ago.
The first of them was associated with the largest glaciation in the history of the Earth. Its traces have been found on all continents except Antarctica, which is now covered with glaciers and THEREFORE poorly studied. There are signs of glaciation in equatorial regions as well. It may be objected that the continents are moving, and those areas that are now on the equator were once near the poles. But now we have learned to determine the latitude of ancient continents. It turned out that Scotland and Belarus, where glacial deposits with an age of about 650 million years were discovered, were at the equator at that time. This means that glaciers then reached the equator. Before this, the Sun provided several percent less heat than it does now. But there was much more carbon dioxide in the atmosphere, and the greenhouse effect warmed the Earth. Plants appeared in the oceans (blue-green, and then “real” algae), they consumed and decomposed carbon dioxide, and “having eaten their own blanket,” brought the Earth to almost complete glaciation. As a result, many algae died out, and the “blanket” gradually recovered.
The second catastrophe occurred 230 million years ago, shortly after another major glaciation. It was not worldwide and covered only the polar and part of the temperate latitudes of the Southern Hemisphere. As has now been proven, climate aridity is associated with glaciations. Ocean water flowed into huge bays surrounded by deserts and evaporated into them. Salts precipitated. One of these bays was located in the east of the East European Plain. The salt left the ocean, but the water, in the course of its great cycle, returned to it. As a result, the salinity of the ocean waters has decreased significantly. Not all marine organisms were able to survive this. According to some data, 97 percent of the organisms that previously lived in the seas and oceans became extinct. The disaster did not affect terrestrial fauna and flora.
Sixty-five million years ago, the most mysterious event in geological history occurred. Dinosaurs and other giant reptiles that had dominated for more than a hundred million years suddenly became extinct. Together with them the inhabitants became extinct ammonites, belemnites and many types of microscopic organisms that formed the seas. Dozens of hypotheses have been proposed to explain the extinction, but among them there is not a single one that would be convincing from the point of view of all or at least the majority of researchers. The theory of dinosaur extinction has yet to be created.
In the Mesozoic, when dinosaurs lived, a warm climate reigned throughout the Earth. The water on the surface of the oceans in the polar regions had a temperature of 15 and sometimes 18 degrees. Approximately the same conditions prevailed at the beginning of the Cenozoic - the “age of mammals” - until 35 million years ago. But then very quickly, almost instantly (on the scale of geological time, this “instant” lasted about one hundred thousand years) the temperature everywhere dropped by several degrees. In the tropics it became colder than now, but in the temperate and polar latitudes after the cold snap the temperature was still much higher than today.

Reasons for the cold snap
Until recently, temperature changes were judged mainly from the remains of animals and plants. The cooling was indicated by the extinction of heat-loving species. But it was always possible to say that in the past organisms lived under different conditions than now, and extinction is not associated with cooling, but with something else. Now “thermometers” have been found that allow us to more objectively judge the conditions of the past. The isotopic composition of oxygen contained in ancient organisms is determined. In addition to the most common isotope with atomic weight 16, there is also an isotope with atomic weight 18 - the so-called heavy oxygen. But in the remains of ancient organisms, the content of heavy oxygen varies depending on the temperature of the water in which they lived. The oxygen thermometer showed that about 35 million years ago there was a cooling, and not any other change in the environment.
What was the cause of the cold snap? There are many hypotheses. The first of them is the hypothesis of a decrease in the luminosity of the Sun. But astrophysicists are against it - neither the Sun nor stars similar to it can dramatically change their luminosity. It does not decrease, but grows very slowly and gradually - by about one percentage over 100 million years. Some botanists have suggested that the tilt of the earth's axis suddenly changed. Experts in celestial mechanics refuse to even discuss such a hypothesis; it seems completely ridiculous to them.
Is it possible to explain the cooling by the fact that the Earth’s “blanket” has become leaky - the greenhouse effect of its atmosphere has decreased? To do this, the carbon dioxide content in it had to decrease. It depends on how quickly plants consume carbon dioxide. The more lush the vegetation, the higher the photosynthesis and the lower the CO content in the atmosphere. But when it gets colder, the vegetation becomes less lush, and the carbon dioxide content in the air increases. The greenhouse effect inhibits cooling caused by other factors.
Maybe the Earth “changed clothes” into different, lighter clothes? After all, we, too, dress in white to escape the heat. White surfaces reflect the sun's rays. For the Earth to become more white, extensive glaciers, sea ice and snow fields must appear. They appear only at low temperatures. An increase in albedo (reflectivity) can support cooling, but cannot be its cause.
Before 35 million years ago, snow and ice probably did not exist anywhere except high mountains. But the polar latitudes received as much solar heat as they receive now. Where did the extra heat come from? In winter, there is ice in the Sea of ​​Azov, but the southwestern part of the Barents Sea never freezes. This is explained by the fact that a warm current approaches the northern shores of Europe. Maybe 40-50 million years ago it was more powerful? Alas, this explanation does not fit either. Once upon a time there was no sea at all between Scandinavia and Greenland. Fifty-five million years ago they began to slowly move away from each other, and only about 30 million years ago deep-sea communication was established between the Norwegian-Greenland and Polar basins. There was no sea through which the ancient Gulf Stream could flow!
The oceans and the Earth's atmosphere form a single climate machine. The location of the continents of the Northern Hemisphere did not create conditions for the warm climate of the Arctic. But the situation was saved by the Southern Hemisphere. Australia was then much further south and formed a single continent with Antarctica. Connected with him South America- there was no Drake Passage. Under such conditions, warm currents caused by easterly winds in subtropical latitudes turned south along the eastern coasts of South America and Australia and reached Antarctica. Within its borders a fairly warm climate prevailed and forests of southern beech grew. It was through Antarctica that marsupials, many representatives of the plant world and even freshwater crustaceans penetrated from America to Australia. Two huge eddies in the Southern Hemisphere - one in the Pacific and the other in the Atlantic and Indian Oceans - warmed the temperate and polar latitudes. There was so much heat that it was enough to heat the Northern Hemisphere.
55 million years ago, Australia began to slowly move north. But there was an isthmus between it and Antarctica for a long time, and then the strait was narrow and shallow. Only 35 million years ago, a powerful ocean current arose south of Australia, driven by westerly winds. This has fundamentally changed climatic conditions the whole Earth. Two whirlpools of the Southern Hemisphere merged into one. Now, from the southeastern coast of South America (still connected with Antarctica), the waters of the ocean made an almost round-the-world journey near the coast of Antarctica, the southwestern coast of South America and turned north. Further along the equator they were driven by easterly winds. Through a wide and deep strait between Australia (although it had moved away from Antarctica, it was much further south than now) and Southeast Asia, the current penetrated into Indian Ocean, then turned south and... the cycle repeated.

Glaciers cover Antarctica
In the far and cold south, during the long journey, the waters managed to cool greatly. Then the cooled waters penetrated into tropical latitudes and cooled them as well. The cooling caused the growth of glaciers in East Antarctica. The names East and West Antarctica are arbitrary. In essence, any part of this continent will be north of the South Pole. But European travelers usually went to Antarctica via the Atlantic Ocean. For them, its more rugged part, adjacent to South America, was in the west, and the main, more massive part was in the east. If you mentally remove the modern ice cover, then West Antarctica will turn into an archipelago of islands, while East Antarctica will still remain a continent.
For glaciers to grow, it is necessary that the snow that falls during the winter does not have time to melt in the summer. There is more and more snow, gradually turning into ice under the weight of the overlying layers. Having accumulated in large masses, the ice begins to flow, like lava (but much slower). Streams of ice move in the mountain valleys, while on the plains huge ice sheets and domes with relatively steep edges and a flat middle, similar to loaves, form. This analogy is not accidental - after all, the dough takes the shape of a loaf according to the same hydromechanical laws by which ice takes the shape of a dome. Both dough and ice can be considered very viscous liquids.
In the center of East Antarctica are the Gamburtsev Mountains. Now they are buried under the ice. The mountains were discovered by measuring the thickness of the glacier.
On the tops of the Gamburtsev Mountains, glaciers could have appeared even before the cold snap began. When the temperature dropped, glaciers occupied the entire mountain range. A cold air mass formed above it, which cooled the surrounding area. The larger the glaciers became, the better the conditions were for their further growth. Very quickly (of course, in a geological sense), in just a few tens of thousands of years, glaciers occupied the entire East Antarctica and reached its shores. But they almost never descended into the sea and almost never gave birth to icebergs.
The emergence of an ice sheet covering an area of ​​10 million square kilometers had a huge impact on the climate and greatly intensified the initial cooling. Ice covered seven percent of the entire land surface. Snow began to fall and sea ice appeared. Huge white surfaces reflected the sun's rays. As a result, the entire Earth has become colder - not only in the Southern, but also in the Northern Hemisphere. The cooling was accompanied by increased aridity - it was at this time that the Sahara Desert was formed.
The growth of glaciers also caused a decrease in sea levels. Water constantly evaporates from its surface, but just as constantly it returns back - the moisture that is transferred by air currents to land, then flows down rivers again into the ocean. But when glaciers grow, the snow that falls on them does not return to the ocean, but is used to build glaciers: the volume of water bound in the glaciers is, as it were, subtracted from the volume of the ocean. 35 million years ago, sea levels dropped by about sixty meters. As a result, vast shallow waters turned into dry land. The sea has left most of the East European Plain and Western Siberia.
The vegetation has changed dramatically. Before the cold snap began, palm trees grew all the way to the coast of Kara and Sea of ​​Okhotsk. When it became colder, they survived only in the southern part of the East European Plain, in Central Asia and in the Vladivostok region.
But the most important changes have undergone animal world. Until 35 million years ago, polytuberculates were widespread - small animals similar to rodents, but with a completely different internal structure. They became extinct and were replaced by rodents. Ancient predators and ancient ungulates became extinct, and in their place the development of modern predators and ungulates began. Changes in the order of primates are of great importance. Until 35 million years ago, only lemurs and tarsiers, the lower primates, were common. Now lemurs are found in Madagascar, but in the rest of the tropical zone, most of them died out with the onset of cooling. Lemurs were replaced by monkeys.
So, the main features of the nature around us were formed 35 million years ago as a result of the beginning of glaciation in East Antarctica. Glaciation was a cause, but it was not the root cause. Everything, as we already know, began with the separation of Australia and Antarctica and the movement of Australia to the north.

The Long Journey of Earth's Nature
35 million years ago, only the basic features of modern nature arose, but it was still not very similar to what we see today. The earth had a long and difficult journey ahead of it. Australia's northward movement continued; about 20 million years ago, the deep-sea strait that separated it from South-East Asia(shallow straits still exist there). Equatorial current Pacific Ocean, which had previously penetrated into the Indian Ocean, turned south along the coast of Australia and began to warm the temperate latitudes of the Southern Hemisphere. In the north, deep-sea communication was finally established between the Norwegian-Greenland and Polar basins, and warm waters penetrated into it. Warming occurred in both the north and the extreme south.
Alas, it was short-lived. 25 million years ago, South America began to move away from Antarctica. 12-14 million years ago the strait between them became quite wide and deep. The Southern Circular Current began to pass through the Drake Passage, encircling Antarctica. Water exchange between tropical and temperate latitudes of the Southern Hemisphere has again sharply decreased. It got colder in the polar latitudes, but it became warmer in the tropics - cold waters from the south no longer reached there. It was then that modern climatic contrasts arose, when some places suffer from heat, while others suffer from cold. The glaciers of Antarctica have increased - they also occupied West Antarctica.
Cooling in temperate latitudes caused increased aridity. It was then, about 12 million years ago, that the steppes arose in the south of the East European Plain. Herds of hipparions roamed the steppes of Eurasia and the savannas of Africa - three-toed relatives of horses that moved from America along the land “bridge” that existed on the site of the modern Bering Strait. Ramapithecus, which can be considered our direct ancestors, spread to southern Asia and Africa. Their height was small - about a meter, but they already walked on two legs.
About three million years ago, ice sheets appeared in the Northern Hemisphere. They covered Greenland, Iceland and the land that was in place of the Barents Sea. The emergence of new genera of animals - elephants, bulls and horses - is associated with new cooling and increased aridity. In East Africa, Australopithecus (descendants of Ramapithecus) began to hunt using the first stone tools - they turned into people.
About a million years ago, glaciation swept across the temperate latitudes of the Northern Hemisphere. At the edge of the glacier, very cold and dry steppes dominated, mammoths and hairy rhinoceroses grazed in them. The glaciers advanced and then retreated again. Our time falls on one of the periods of least development of glaciers.
Will acknowledging drastic changes lead to some incorrect conclusions? Indeed, at the beginning of the 19th century, some believed that after each catastrophe there follows a new “act of divine creation.” The author of the “catastrophe theory” himself, Georges Cuvier, did not write anything like this. In his opinion, the deserted continent was inhabited by animals that came from other places. Cuvier did not specify how they appeared there. Some of Cuvier’s students wrote about “divine creation”, trying to reconcile his views with religious ideology.
What is the situation today, when no one doubts the validity of evolutionary theory? It has now been proven that many organisms that suddenly appeared after the disaster actually existed before it, but were very rare or found only in certain limited areas. When the “masters of the Earth” perished, the former pariahs came to the forefront of geological history. They quickly multiplied, spread widely and became the new masters of the Earth. At first, there were no organisms that could master all the conditions suitable for life. This gave impetus to rapid evolution.
Monkeys, for example, existed before the latest disaster, but were much less common than lemurs. It is possible that if the warm and humid climate had remained, lemurs would still dominate. At one of the reports I gave in Moscow, the question was asked: “If the glaciation of Antarctica had not begun, would we have lived among subtropical forests?” I had to give the following answer: “There would indeed be subtropical forests here, but it would not be us who would live in them, but lemurs with huge eyes.” Cooling increased the rate of evolution many times over. Great catastrophes are, in essence, revolutions in the development of the organic world. Without them, it would have developed much more slowly.
In this regard, we recall the words of the great English naturalist of the 17th century, William Harvey: “Do not praise, do not blame - everyone worked well.” Once upon a time, supporters of Georges Cuvier and Charles Lyell argued fiercely among themselves. Now it is clear that both were right. Both slow and gradual development and disasters are explained by natural causes.
The last great “catastrophe” is associated with the beginning of glaciation in Antarctica. Will another catastrophe occur if human-caused warming causes glaciers to melt and sea levels to rise by 70 meters? A look into the past shows that there will not be a “global flood”. After all, 20-30 million years ago the volume of glaciers was already close to what it is today. At that time, a rather warm climate prevailed in temperate and polar latitudes. The ice sheet of East Antarctica was melting at the edges, but did not decrease in size - much more snow fell on its surface than now.
In my opinion, the upcoming warming will also lead to heavy snowfalls. The largest ice sheets may even increase their thickness as a result. They will produce fewer icebergs and melt a little at the edges, but will not decrease in volume until the volume of melting exceeds the volume of snow water received by the glaciers each year. For this to happen, a warming of 10-12 degrees is needed. Only after this will Antarctica's glaciers begin to disintegrate and sea levels to rise. But there is no talk of such warming in the foreseeable future. With less warming, sea levels could even drop slightly as Antarctic glaciers become thicker.
Homo sapiens, Homo sapiens, evolved from apes that spread widely 35 million years ago. If humanity lives up to it high rank and will act wisely, the last great “catastrophe” will not truly turn into a catastrophe.

D. Kvasov, Doctor of Geographical Sciences

This I know

1. Tell us about geographical location Antarctica. What oceans wash the continent? What currents pass along its banks?

The territory of Antarctica is almost entirely within the southern polar circle. The continent is located in three hemispheres at once - Southern, Eastern and Western. The continent is washed by the Pacific, Indian and atlantic oceans. The most powerful current of the Western winds passes around Antarctica.

2. What are ice shelves? How are icebergs formed?

Ice shelves are ice that covers not only the mainland, but also slides in tongues onto the adjacent seas and islands.

Icebergs form when huge blocks of ice break off from an ice shelf.

3. What are katabatic winds and what causes their formation?

Over Antarctica, an area of ​​constant strong cooling is formed due to the glacier. As a result, a high pressure area forms over the continent. Masses of cold air flow from the center to the outskirts, forming strong katabatic winds.

4. When does summer begin in Antarctica? Winter?

Antarctica lies entirely in the Southern Hemisphere. Therefore, summer begins on the day of the winter solstice (December 21), winter - on the day of the summer solstice (June 22).

5. Why do Antarctica have negative temperatures all year round?

Negative temperatures throughout the year are associated with the position of the continent beyond the Arctic Circle. The angle of incidence of the sun's rays is very small. In addition, snow and ice reflect more sunlight back into the atmosphere, so the earth's surface does not warm up.

I can do this

7. Consider the profile of the structure of Antarctica (see Fig. 105). Draw a conclusion about the structure of Ice Antarctica and the relief of Rocky Antarctica?

The relief of Stone Antarctica is characterized by very low absolute heights and small elevation differences. Icy Antarctica has the shape of a bath. The thick ice cover has enormous mass. Plastic ice masses flow from the center to the periphery, forming a convex shape. Icy Antarctica is the highest continent.

8. Look at the photo in Fig. 107. How did penguins adapt to life in harsh conditions?

The plumage of penguins is different from that of other birds: the feathers are small, hard, dense, similar to scales, and fat accumulates under the skin of penguins. Penguins cannot fly, but they are excellent swimmers, which helps them get food in the ocean. Penguins live in large groups. During snow storms, they keep warm by becoming tightly packed to each other and constantly moving from the edge to the center.

This is interesting to me

9. Prepare a message on the topic “How Antarctica was discovered.”

How Antarctica was discovered

The initial stage - the discovery of islands around Antarctica and the search for the mainland (16th century - early 19th century)

Long before the discovery of the mainland, various assumptions were made about the existence of a hypothetical Southern Land, in search of which expeditions were sent that discovered large islands around Antarctica. In 1768-71, J. Cook led an expedition that was heading in search of the southern continent. Having explored New Zealand, the expedition discovered a strait between its North and Southern Islands(later named after Cook) and established that New Zealand is not a protrusion of the southern continent, as previously thought, but an archipelago of two islands. In 1772-75, Cook, in the second expedition dedicated to the search for the southern continent, was the first of the navigators to cross the Antarctic Circle, but he did not find the mainland and stated that it was impossible to find it at all due to the ice making the land inaccessible.

The second stage - the discovery of Antarctica and the first scientific research (19th century)

The discovery of Antarctica as an ice continent belongs to the Russian round-the-world naval expedition led by F. F. Bellingshausen and M. P. Lazarev on the sloops “Vostok” and “Mirny”. In January-February 1820, Russian ships came close to the Dronning Maud Land ice shelf four times. The Russian expedition discovered Fr. Peter I, Alexander I Land and several islands in the South Shetland archipelago. In 1820-1821, English and American hunting ships (leaders E. Bransfield and N. Palmer) were close to the Antarctic Peninsula (Graham Land). The voyage around Antarctica and the discovery of Enderby Land, the Adelaide and Biscoe Islands were made in 1831-33 by the English navigator J. Biscoe. In 1838-42, three scientific expeditions visited Antarctica: French (J. Dumont-D'Urville), American (C. Wilkes) and English (J. Ross). The first discovered Louis Philippe Land, Joinville Land, Adélie Land and Clary Land (for the first time landed on the coastal rocks), the second - Wilkes Land, the third - Victoria Land, coastal islands, and also for the first time walked along the giant Ross Ice Shelf, calculated the location of the South Magnetic Pole .

After these voyages, a fifty-year period of calm began in Antarctica. Interest in Antarctica increased at the end of the 19th century. due to the fact that due to predatory extermination the number of whales in the Arctic has decreased. Several expeditions visited Antarctica: the Scottish expedition on the ship "Valena", which discovered the Land of Oscar II, later so called by the Norwegian expedition on the "Jason" and "Antarctica"; the latter discovered the Larsen Coast and landed on the coast of Antarctica in the area of ​​Cape Adare; the Belgian under the leadership of Antarctic Gerlache, who spent the winter in Antarctica on the drifting ship "Belgica", and the English on the "Southern Cross", which organized the wintering at Cape Adare (the beginning of the wintering of K. Borchgrevink).

The third stage is the study of the coast and interior regions of Antarctica (first half of the 20th century)

At the beginning of the 20th century, expeditions to the polar mountain ranges and glaciers of the mainland began one after another. Preparations begin to reach the planet's South Pole. In 1909, the Norwegian Roald Amundsen is preparing for this very difficult and dangerous crossing of the icy continent. On January 14, 1911, the Norwegians landed on the coast of Antarctica in Whale Bay. Together with them, an English expedition led by Robert Scott set off to conquer the pole, arriving in Antarctica a few days earlier - on January 3. Amundsen's proposed route was 100 kilometers shorter than Scott's, but it covered more difficult terrain. But Amundsen calculated all stages of the campaign with amazing accuracy. Between 80° and 85°, every degree he set up warehouses with food and fuel, and to make them easy to find, he installed high milestones with flags. Amundsen's trek began on October 20, 1911, with four companions on a dog-drawn sleigh. Beyond the 85th parallel, a difficult climb began from the Ross Ice Shelf to the ridge, which Amundsen named the Queen Maud Ridge in honor of the Norwegian queen (later it was proven that this ridge belongs to the Transantarctic Mountains). When some of the provisions had already run out, Amundsen ordered the killing of the extra dogs in order to feed them with the meat of the remaining animals, however, the travelers themselves ate this meat, because provisions were running low. The Norwegian expedition reached the South Pole on December 15, 1911. They pitched a tent on a high plateau, 2800 meters high, and raised the Norwegian flag there. Roald Amundsen and his companions became the first people to conquer the South Pole. On December 17 they turned north. They had to kill one dog every three days, so people and animals ate fresh meat until they reached the 85th parallel, where the first warehouse they left was located. Having traveled 2,800 km round trip, they returned to Whale Bay on January 26, 1912 after a 99-day ice voyage.

At this time, Robert Scott planned to reach the Pole on a motor sleigh, Indian ponies and dogs. They set off on November 2, 1911. However, the technology failed Scott, the motor sled soon had to be abandoned, and beyond the 83rd parallel the ponies had to be killed when there was nothing to feed them. At 84° the dog sleds were sent back, and the British themselves pulled the heavily loaded sleighs. Beyond the 85th parallel, Scott ordered four people to return, and at 87°30' three more. Only five people went further: Robert Scott, doctor Edward Wilson, officers Lawrence Oates and Henry Bowers, and non-commissioned officer Edgar Evans (Pictured). The last 250 km were especially difficult for them. The sleigh had to be dragged through dry, loose snow; per hour they moved no more than 2 km, and in a day they moved less than 10 km. When there were several miles left to the Pole, Scott wrote in his diary: “... we saw a black dot ahead... [which turned out to be] a black flag tied to a sleigh runner. The remains of a camp were visible nearby... The Norwegians were ahead of us. They were the first to reach the pole. Terrible disappointment! On the road from their base to the Pole, the British set up ten intermediate warehouses for provisions and fuel. On the way back, their immediate goal was to quickly get to the next warehouse in order to replenish fuel supplies. However, the travelers' strength quickly faded. Soon the youngest of them, Evans, began to feel signs of mental illness, he fell behind, fell until he was completely exhausted. On February 17 he passed away. The further journey turned out to be even more difficult. Scott's team increasingly lost their way. At the end of February, when “fuel became terribly low,” severe frosts began. Scott's notes showed how their will to live disappeared and their despair grew. But they didn’t give up until the very end and dragged behind them about 15 kilograms of the most valuable rock samples collected on the way to the Pole. Friday March 16th or Saturday March 17th, Scott wrote in his diary: “I lost track of the numbers, but it seems to be the last one. Our life is a pure tragedy. Ots said: “I’ll go for a walk. Maybe I won’t be back soon.” He went into a snowstorm, and we didn’t see him anymore... we knew that... Ots was going to his death, and we tried to dissuade him, but... we realized that he was acting like a noble man...” March 29: “From the 21st a continuous storm raged... On the 20th we had enough fuel for two cups of tea each and enough dry food for two days. Every day we were ready to go... but there was no way to leave the tent - the snow was blowing and swirling. I don’t think we can hope for anything else now...” Robert Scott's last entry: "For God's sake, do not abandon our loved ones." The search party found their snow-covered tent only in the spring - November 12, 1912. All the travelers of Scott's expedition died, he himself died last, throwing away the lapels of his sleeping bag and unbuttoning his jacket. They were buried in this place. On the memorial cross installed in the ice in memory of the expedition, an epitaph was carved: “To strive, to seek, to find, and not to yield.” The whole of Great Britain was deeply affected by the news of the death of its heroes. It is worth saying that Scott’s last request found a response in the hearts of the British and was fulfilled. A significant amount collected throughout the country provided a comfortable existence for the relatives of the deceased travelers.

After the conquest of the South Pole by Amundsen and Scott, Antarctic exploration continued with renewed vigor. In December 1911, Douglas Mawson made his first expedition. For wintering, his expedition chose Adélie Land, which, as it turned out, was a place with the harshest climate on Earth. Often the average daily winds here reached a speed of 44 m/s. Mawson had to observe winds of 90 m/s, when the speed of a destructive hurricane was only 30 m/s. Added to all this was the highest amount of precipitation in Antarctica - 1600 mm per year. The campaign of 1912–1913 almost became fatal for Mawson himself, his entire team died, and he himself returned to base only five months later. However, during the expedition, the discoveries of Charles Wilkes were confirmed, vast territories were explored, and the description of the information collected amounted to 22 volumes. In the 20s of the 20th century, flights over Antarctica began, which made it possible to explore the mountains and lands in the depths of the continent. Among the researchers of this time, it is necessary to mention the American pilot Richard Byrd, the Norwegian captain Nils Larsen, and the American engineer Lincoln Ellsworth.

The first Soviet Antarctic scientific expedition, led by the experienced polar explorer and oceanographer Mikhail Mikhailovich Somov, landed on the coast of the Davis Sea on January 6, 1956. Nearby, with the help of the crews of two diesel-electric ships “Ob” and “Lena,” the village of Mirny was built. Antarctic sector between 80° and 105° East. was not chosen by chance. The coast of the mainland was mapped very roughly; during the work of Soviet researchers, many new islands, bays, capes and glaciers were discovered. In addition to the base in the village of Mirny, by the end of 1956, two more stations appeared: Pionerskaya and Oasis station.

There are currently 37 stations operating in Antarctica. Argentina, which has 6 stations here, is actively developing the mainland. After the collapse of the USSR and the resulting economic difficulties, Russia was forced to freeze some of them. Now there are 5 Russian stations on the mainland: Bellingshausen (62°12" S 58°56" W), "Vostok" (78°27" S 106°52" E. ), "Mirny" (66°33" S 93°01" E), "Novolazarevskaya" (70°46" S 11°50" E), "Progress" ( 69°23" S 76°23" E) – (Data from the Russian Antarctic Expedition: the USA, Australia and Chile each have 3 stations on the mainland. Great Britain and China have two stations each. Also, one station each has: Norway, France, New Zealand, Japan, Brazil, Uruguay, South Korea, South Africa, Germany, India, Poland, Ukraine. There is also one joint station between France and Italy.

Since 1961, there has been an agreement signed by all leading countries, according to which territories south of 60° S. are demilitarized and free of nuclear weapons. Also, no country in the world has the right to claim these territories. It provides for freedom of scientific research and encourages international cooperation to ensure that Antarctica is used for the benefit of all mankind.

What are the reasons for the formation of glaciers in Antarctica?

A study led by University of Massachusetts geoscientist Robert DeConto has established an alternative theory for why Antarctica suddenly became covered in glaciers 34 million years ago. His theory challenges previous ideas about ice formation.

Deconto in collaboration with David Pollard of Penn State State University, published his findings in the January 16 issue of the journal Nature. His work was funded by the National Science Foundation.

Scientists have long known that Antarctica was not always covered with layers of multi-kilometer ice. Once upon a time, this continent was covered with green vegetation and dinosaurs walked on it,” says Deconto. “It is believed that Antarctica, then part of a single continent of continents - Pangea, was a temperate zone with a tropical forest.

Previous studies of microfossils and ocean chemistry have already shown that Antarctic ice formed very quickly - within 50,000 years or less. Dramatic climate change occurred during the Oligocene and Eocene eras. It remains a mystery - why did this happen and why so quickly?

A theory put forward in the 1970s proposed that plate tectonics was the driving force in the Antarctic Freeze. Pangea was breaking apart. Australia moved further north, opening an ocean channel known as the Tasmanian Passage. And scientists concluded that because South America drifted and moved far from Antarctica, the Drake Passage opened. This was thought to be the last barrier to the ocean current circumnavigating the entire continent. This flow deflected warmer northern waters and served to keep the continent cool and the southern ocean waters cool. This theory was known as "Thermal Insulation".

Deconto and Pollard set out to determine how important the discovery of the southern ocean currents was in the rapid freezing of Antarctica. Among the factors they considered: ocean currents; plate tectonics; carbon dioxide content in the atmosphere; and changes in the Earth's orbital parameters.

Using computer modeling, scientists have essentially reconstructed a picture of the world 34 million years ago, including the detailed topography of Antarctica and the placement of drifting continents. Topography was especially important because if there are a lot of mountains, then they can serve as a very good catalyst for glaciers to grow even in summer.

The study found that the critical factor in the rapid cooling of the continent and its covering with ice was not the discovery of new ocean currents, but a change in carbon dioxide in the atmosphere.

Carbon dioxide is a very important component that affects climate change. Current global warming and rising levels of CO2 in the atmosphere may indicate that Antarctic ice will melt very quickly.

Antarctic glaciers are the greatest in the world, as they represent the drainage system of the world's largest ice sheet. Many of the glaciers would be more accurately called ice streams, since they do not have clearly defined boundaries. Where the glacier flows into the bay, reaching the shore, the ice floats and an ice shelf forms. A glacier descending from a flat section of the coast does not form an ice shelf, but, once afloat, continues to flow directly into the sea. This protrusion is called a glacier tongue and is usually very unstable, although the tongue of the Erebus Glacier, which flows into McMurdo Sound, often extends more than 10 km out to sea before breaking off. Antarctica's largest ice shelves, the Ross and Filchner ice shelves, are so large that they are fed by several glaciers and ice streams. The Ratford Glacier, which flows near the Ellsworth Mountains into the southwestern corner of the Ronne Ice Shelf, reaches more than 1.6 km. in thickness in the place where it finds itself afloat, and demonstrates the most powerful floating ice known in the world.

Lambert Glacier - the largest and longest glacier in the world

The Lambert Glacier in East Antarctica flows approximately north along the 90°E meridian through the Prince Charles Mountains into Prydz Bay. Some tourist ships sail close to these places, but to see the glacier, you need to move deeper into the mainland, preferably by helicopter.

The Lambert Glacier in East Antarctica is probably the world's largest glacier. Its width reaches 64 km. where it crosses the Prince Charles Mountains, and its length, including its offshore extension, the Amery Ice Shelf, is about 700 km. It collects ice from about a fifth of the East Antarctic ice sheet; if you do the math, it turns out that approximately 12% of the fresh water on Earth passes through the Lambert Glacier. This astounding figure is as difficult to comprehend as the majesty of the Antarctic glacier. The popular image of an Alpine or Himalayan glacier flowing down a slope like an icy river is, strictly speaking, inapplicable to the Lambert Glacier due to its colossal size. Shooting from space - The best way see a large enough part of it to understand that it really is a glacier.

Glaciers move slowly. The fastest, the Jakobshavn glacier in Greenland, covers 7 km. per year, while the Lambert Glacier slides down the Prince Charles Mountains at a rate of only 0.23 km. per year, gradually accelerating to 1 km. per year at the Amery Ice Barrier. However, although it does not move quickly, it moves powerfully, since about 35 cubic meters passes through it per year. km. ice.

The surface of a glacier like this when viewed from high altitude, for example from an airplane, is marked by streamlines - natural ribs of ice indicating the direction of its movement, like the strokes of a giant brush on the oil of a panoramic painting. From the ground, these ribs are invisible, but they can be identified by areas of parallel cracks. They are created by different speeds of ice movement inside the glacier; they can be formed by unevenness of the glacier bed or obstacles in its path. In this case, a zone of random cracks is formed, as, for example, in places of a sharp change in the angle of inclination of the terrain; this phenomenon is called an icefall and is analogous to a waterfall on a river. Some of the cracks below Gillock Island, formed because the glacier is forced to flow around this island, reach more than 400 m in width and 40 km. in length, surpassing in size some Alpine glaciers.

Snow bridges span these huge cracks, or rifts, instilling timidity in the traveler forced to use them. However, despite their enormous size, crossing them is quite safe, since the additional weight of the tractor is infinitesimal compared to the weight of the snow supported by the bridge. Sir Vivian Fuchs' Transantarctic Expedition (1955-1958) encountered similar cracks upon leaving the South Pole, and is said to have descended the slope to a bridge and climbed the slope again on the other side. The main danger was represented by small cracks at the edge of the bridge itself. Elsewhere, traveling across the glacier can be relatively easy, as long as you avoid known areas of crevasses. Like the rivers of Africa to the pioneers of that continent, the glaciers of Antarctica often offer explorers an obvious route into the interior of the continent. Shackleton discovered the Bridmore Glacier, which provided a direct route from the Ross Ice Shelf to the Polar Plate; Scott and four of his companions chose the same route for their fateful journey to the Pole.

An ice shelf typically forms where glaciers and ice streams flowing from a continental ice sheet flow into a gulf. Having descended along the bottom to a certain depth - usually 300 m - the ice becomes floating and various glaciers merge into a single field. This field continues to grow until it fills the bay. Going beyond the bay, no matter how large it is, the front part of the glacier, having lost the restraining influence of the mouth of the bay, loses stability and becomes vulnerable to the forces of the open ocean. The glacier gradually breaks off along a line connecting the extreme points of the bay, and the glacier “calves” occurs. The ice shelf also loses ice, melting from below and forming cold bottom currents that move north over the ocean floor to then rise to the surface, oxygenating tropical waters. Although the glacier, on the other hand, thickens due to the fall of snow on its surface, the overall result is that it becomes thinner in the direction open sea. The ice barrier - the edge of the glacier facing the sea - reaches a thickness of approximately 180 m and rises above sea level by 20-30 m. An object left on the surface of the ice shelf will gradually descend as it approaches the ocean.

Ross Glacier is the largest ice shelf in Antarctica

The Ross Ice Shelf can usually be reached by ship or plane from New Zealand during the transfer of personnel and supplies to the US McMurdo Station and New Zealand's Scott Base. Tourist ships also visit these places, but passengers rarely get to see anything other than the cliff of the ice barrier.

Captain James Cook, during his second voyage, in 1772-1775, became the first person to penetrate the high latitudes of Antarctica, but he never managed to see the continent; all attempts he made to sail further south were thwarted by pack ice. It was only in 1840 that Captain James Clark Ross, by then Britain's most experienced Arctic navigator, sailed south and successfully broke through the belt of pack ice into the waters now known as the Ross Sea. He discovered Ross Island, and to the east of it a ridge, which he called the Victoria Barrier and about which he wrote: “... we had the same chance of overcoming this mass as if we were trying to swim through the rocks of Dover.”
Ross was shocked. Ice cliffs ranging from 46 to 61 m high hung over his ships, and to the south nothing was visible except an endless icy plain. Strictly speaking, the Ross Ice Shelf is an approximately triangular slab of ice whose thickness ranges from 183 m at the ice barrier at its leading edge to 1300 m in the landward part. Its area is 542,344 sq. km. - This more territory Spain and almost equal to the area of ​​France; and since it is afloat, it rises and falls under the influence of the tides. Large pieces of shelf ice break off and turn into table icebergs; the largest recorded, with an area of ​​31,080 sq. km, was larger than Belgium.

The Ross Ice Shelf is fed by glaciers. Many of them, such as the Beardmore Glacier, come down from the Transantarctic Mountains, but glacial streams coming from Mary Byrd Land bring more ice. A ship sailing through the Ross Sea in 1950 encountered an iceberg with a corner of a building sticking out of its side, identified as a fragment of a house from one of Admiral Byrd's Little America stations, built about 30 years earlier.

The shelf ice is mostly free of cracks and is easy to move around. It is relatively flat, but the progress of the sled depends on the condition of the surface. Snowy areas are difficult to navigate whether the sled is pulled by people, dogs or tractors. Often there are sastrugi - dense, wind-created ridges of snow that, if their height exceeds 30 cm, can make travel difficult. It’s especially disappointing when the depressions between the ridges are filled with soft snow, the surface appears smooth, but people and tractors fall through.