The Quaternary period of the Cenozoic era: animals, plants, climate. Periods of the geological history of the Earth. Ice Age. Quaternary period of the Cenozoic era: description, history and inhabitants Description of the periods of the Cenozoic era

The Cenozoic era is the last known today. This is a new period of life on Earth, which began 67 million years ago and continues to this day.

In the Cenozoic, transgressions of the sea stopped, the water level rose and stabilized. Formed modern mountain systems and terrain. Animals and plants acquired modern features and spread throughout all continents.

The Cenozoic era is divided into the following periods:

• Paleogene;
• neogene;
• anthropogenous.

Geological changes

At the beginning of the Paleogene period, the Cenozoic folding began, that is, the formation of new mountain systems, landscapes, and reliefs. Tectonic processes took place intensively within the Pacific Ocean and the Mediterranean Sea.

Mountain systems of the Cenozoic folding:

1. Andes (in South America);
2. Alps (Europe);
3. Caucasus mountains;
4. Carpathians;
5. Middle Ridge (Asia);
6. Partially Himalayas;
7. Cordillera Mountains.

Due to global movements of vertical and horizontal lithospheric plates, they have acquired a form corresponding to the current continents and oceans.

The climate of the Cenozoic era

Weather conditions were favorable, a warm climate with periodic rains contributed to the development of life on Earth. In comparison with modern average annual indicators, the temperature of those times was higher by 9 degrees. In a hot climate, crocodiles, lizards, turtles adapted to life, which were protected from the scorching sun by developed outer covers.

At the end of the Paleogene period, a gradual decrease in temperature was observed, due to a decrease in the concentration of carbon dioxide in the atmospheric air, an increase in the land area due to a drop in sea level. This led to glaciation in Antarctica, starting from the mountain peaks, gradually the entire territory was covered with ice.

Animal life of the Cenozoic era

At the beginning of the era cloacal, marsupial, and first placental mammals were ubiquitous. They could easily adapt to changes in the external environment and quickly also occupied the water and air environments.

Bony fish have developed in the seas and rivers, birds have expanded their habitat. Formed new species of foraminifera, mollusks, echinoderms.

The development of life in the Cenozoic era was not a monotonous process, temperature jumps, periods of severe frosts led to the extinction of many species. For example, mammoths that lived during the period of glaciation, could not survive to our times.

Paleogen

In the Cenozoic era, insects made a significant leap in evolution. Mastering new sites, they survived a series of adaptation changes:

• Got a diverse color, size and shape of the body;
• got modified limbs;
• species with complete and incomplete metamorphosis appeared.

Huge mammals lived on land. For example, hornless rhino is indricoteria. They reached a height of about 5m and a length of 8m. These are herbivores with massive three-fingered limbs, a long neck and a small head - the largest of all mammals that ever lived on land.

At the beginning of the Cenozoic era, insectivorous animals were divided into two groups and evolved in two different directions. One group began to lead a predatory lifestyle and became the ancestor of modern predators. The other part fed on plants and gave rise to ungulates.

Life in the Cenozoic in South America and Australia had its own characteristics. These continents were the first to separate from the Gondwana continent, so evolution here went differently. For a long time, the mainland was inhabited by primitive mammals: marsupials and monotremes.

Neogene

In the Neogene period, the first humanoid monkeys appeared. After the cooling and reduction of forests, some became extinct, and some adapted to life in the open. Soon primates evolved to primitive people. So began anthropogenous period.

The development of the human race was rapid. People begin to use tools for food production, create primitive weapons to protect themselves from predators, build huts, grow plants, and tame animals.

The Neogene Cenozoic period was favorable for the development of ocean animals. Especially quickly cephalopods began to breed - cuttlefish, octopuses, which survived to our times. Among bivalve mollusks, the remains of oysters and scallops were found. Small crustaceans and echinoderms, sea urchins were found everywhere.

Plant World of the Cenozoic Era

In the Cenozoic, the dominant place among plants was occupied by angiosperms, the number of species of which in the Paleogene and Neogene periods increased significantly. The spread of angiosperms was of great importance in the evolution of mammals. Primates might not appear at all, since the main food for them is precisely flowering plants: fruits, berries.

Conifers developed, but their numbers decreased significantly. The hot climate contributed to the spread of plants in the northern regions. Even beyond the Arctic Circle, plants from the Magnolia and Beech families were found.

Camphoricum camphor, figs, plane trees and other plants grew in Europe and Asia. In the middle of the era, the climate changes, cold sets in, displacing plants to the south. The center of Europe with a warm and humid environment has become a great place for deciduous forests. Representatives of plants from the Bukovye family (chestnuts, oaks) and Birch (hornbeam, alder, hazel) grew here. Coniferous forests with pines and yews grew closer to the north.

After the establishment of stable climatic zones, with lower temperatures and periodically changing seasons, the plant world underwent significant changes. Evergreen tropical plants have been replaced by species with falling leaves. The Cereals family stood out as a separate group among monocotyledons.

Huge territories were occupied by steppe and forest-steppe zones, the number of forests was sharply reduced, and grassy plants mainly developed.

The Cenozoic era, or as it is often called Cenozoic, has been going on for 65.5 million years. It began after the extinction of many species of animals at the end of the Cretaceous. Note that we live in the Cenozoic today. The name translated from Greek means "new life." The Cenozoic era includes the following periods: Tertiary and Quaternary. The first, in turn, consists of the Paleocene and Pliocene, and the second - the Pleistocene and Holocene. However, most often in the literature, geologists do not use this separation, since changes in evolution are very small.
In short, the development of life in the Cenozoic era has reached a peak in the history of the Earth. This is especially true for marine, flying and terrestrial species. If you look from a geological point of view, it was during this period that our planet acquired its modern appearance. Thus, New Guinea and Australia now became independent, although they had previously been annexed to Gondwana. These two territories shifted closer to Asia. Antarctica has become in its place, and stands on it to this day. The territories of the Americas are united, but nevertheless today they are divided into two separate continents. The Cenozoic era presentation is located below:

  After the threat posed by the large dinosaurs disappeared, the Cenozoic era became a time of prosperity for mammals. The first mammals got along quite peacefully with birds, common reptiles and invertebrates. Climatic conditions became colder and drier when the continents separated from each other and took roughly their present positions. Some scholars believe that it was at this time that the Himalayas rose.

The presence of year-round grazing allowed whole herds of pasture animals to thrive, along with the now extinct lateral branches of the evolutionary tree. Temperatures continued to decline as the continent of Antarctica formed. The emergence of a branch of homo sapiens among mammals occurred in the last few minutes of this era (in geological terms) along with the use of primitive tools, the production of fire, and the invention of the wheel, while older species became extinct.

The Cenozoic era originates from the Tertiary period. This name is already a little outdated today, but at the moment it is the largest stage. This period ended 1.8 million years ago when the ice age began (so far the last in the history of the Earth). This name was given to the stage by the Italian Arduino. At first, he divided all the periods of the Cenozoic era in numerical order, from the primary to the tertiary. After some time, the Quaternary also entered here. Then, in 1828, the penultimate stage was well studied by the Scottish specialist Charles Lyell. Moreover, he introduced so much information that the tertiary had to be divided into four stages at once. In his teachings, he settled on fossil mollusks, that is, on their population density. These creatures were not chosen in vain, because their appearance resembles modern species. The era gave the Greek "names": Eocene, Miocene, as well as the Ancient and New Pliocene. Such a distribution was well suited to Italy, but the separation was not characteristic of other parts of the globe. Subsequently, during research, no one resorted to the help of mollusks, and the era underwent changes. Now, according to the new standard, the tertiary period consists of a Paleogene and a Neogene.
  Briefly talk about each. The first lasted for 40 million years. It was during this period that life in the Cenozoic era became much brighter and richer. Many representatives of the fauna settled on territories previously occupied by dinosaurs. Some species have undergone evolutionary changes. 24.6 million years ago, the period came to an end due to the onset of climate drainage. It is divided into three eras, the names of which are no longer used today.
Then the Cenozoic era moved to a new stage - Neogene. Its duration was 22 million years. The character is significantly different from its predecessor. In this period, the number of species of mammals decreased, but at the same time, they became more closely connected with each other. We also note that the climate continues to dry out, while the average air temperature gradually drops. Thus, 1.8 million years ago the ice age began. The Tertiary period is conditionally distributed on the Miocene and Pliocene.
The Cenozoic era becomes much more interesting in the Quaternary, often called the anthropogen. It is he who is the final stage of the Cenozoic, began 2.6 million years ago. In this era, this period is the shortest. First of all, it is characterized by the acquisition of a modern type of terrain, and the most important thing is the appearance of a person. By the way, paleontologists find it difficult to examine the remains, since in this case it is impossible to determine the age using isotopes. Here, only one effective method is radiocarbon analysis. You can apply other methods, the foundation of which lies in the decay of short-lived isotopes. As you can see, for scientists, the Quaternary period is the most specific. It, in turn, contains two eras: the Pleistocene and the Holocene. It is interesting to know what the shape of the Earth was like, when the Cenozoic era reigned, the presentation will tell you:

During the “reign” of the first, huge glaciations reigned, but at the same time they cyclically changed with interglacials when the air temperature was acceptable. Already at that time, the climate had acquired a modern character, but this does not concern animals at all. As an example, the extinction of the South American pampa. The reason for this phenomenon is a frequent change in climatic conditions, in some cases, animals were destroyed by ancient people. If you completely move to South America, then we note the disappearance from Earth of a sloth of megateria, a giant saber-toothed cat and an armadillo of a dedicurus. Then we move to North America, there, too, the fauna has undergone changes. In particular, there were no tyrant birds. Perhaps you did not know, but in ancient times camels lived overseas, which later became extinct. Note the disappearance of the American horse, deer, bulls and antelopes. In Europe, mammoths, cave bears and lions, as well as woolly rhinos, disappeared. Misfortune also affected the fate of people, and to be precise, the Neanderthals. It was they who lost the Cro-Magnons in the struggle for power. Only now it is not known in what way they disappeared from the planet: they were killed or all the same they were eaten.
We are now moving to the Holocene, which was a common interglacial era, but had a stable climate. The Cenozoic era during this period lost many representatives of the fauna, in this case the primitive man did not calculate strength. In the middle of the period, people began to use the provided resources wisely, in the process of evolution civilization gained development. It is in the Holocene that the beginning of the technical development of mankind is marked. There are no significant changes in the appearance of animals. In the past period, the number of megateria, epiornis, dodo, and Steller cows was only about a hundred individuals per species. However, in the Holocene era, these representatives completely ended their existence. Again, fault on the part of man.
  As for the climate, it has become much warmer, thus global warming is noted today. Scientists associate these changes with the vigorous industrial activity of people. Subsequently, the temperature rise collapsed Eurasian and North American glacier. The Arctic until recently was one, but at one point the ice cover slowly began to decay. Numerous mountain ice sheets were erased from the face of the Earth. Today they can only be seen in Greenland and Antarctica, since these territories are located near the polar caps. In the XX century, experts originated a teaching in the field of medicine called genetics. Perhaps in the near future they will be able to remove the extinct animals that lived in the Pleistocene. Now we live in the Hologen era.

The Cenozoic era has been studied by many researchers for many years. Most of them are on the staff of INQUA. The main activity of this corporation is connected with the study of the Quaternary period, including our time. The organization began in 1928. The press service provides a lot of information, and therefore it is not difficult to write an essay on the Cenozoic era. Starting from this time, with a cyclic period of 4 years, a meeting of scientists is scheduled, and the venue of the seminars is changed every time. This once again suggests that the Cenozoic era is very popular among scientists. Russia is a member country of INQUA, it represents its commission in this organization. In our country, it is headed by Yu.A. Lavrushin, who is a professor at the Geological Institute of the Russian Academy of Sciences. The Cenozoic era, with the help of world experts, has already been well studied, especially when it comes to animals. After all, technological progress continues its movement. Today, the organization is devoting more and more time to the conservation of species of flora and fauna, in particular, regarding deforestation. Although the designers created modern equipment, they could not invent such cheap artificial paper.
  In total, 18 congresses were held, the last was held in the capital of Switzerland - Bern. In the seminar hall in July 2011, representatives from 75 countries gathered. Scientists themselves argue that it is most difficult for them to study the plant world of the Cenozoic era. After all, this material is poorly preserved to our times, and therefore difficulties arise during the analysis. But today computer models are being created, according to which a report can be compiled on the Cenozoic era.

Cenozoic era ("era of new life") - began 66 million years ago, and continues to this day.

This era is the period immediately following the Mesozoic era. There is an assumption that it originates between the melio - and the Paleogene.

Just at this time, the second mass extinction of animals and plants was observed due to an unknown catastrophic phenomenon (according to one version - a meteorite fall).

Periods of the cenozoic era

• Paleogene (ancient). Duration - 42 million years. Epochs - Paleocene (66 mln - 56 mln years ago), Eocene (56 mln - 34 mln years ago), Oligocene (34 mln - 23 mln years ago)
• Neogene (new). Duration - 21 million years. Epochs - Miocene (23 million - 5 million years ago), Pliocene (5 million - 2.6 million years ago)
• Quaternary (Anthropogenic). It lasts now. Epochs - Pleistocene (2.6 million - 12 thousand years ago), Holocene (12 thousand years ago and until today).

The processes of the Cenozoic era

• Alpine tectogenesis begins, also called neotectonic
• Formed mountains of the Mediterranean Sea, ridges and islands along the Pacific coast
• In areas formed in previous periods, block movements occurred
• Climate is changing, which is becoming more severe
• Deposits of many minerals are being formed - from gas and oil to gold and platinum.

Characteristics of the Cenozoic era

• At the very beginning of the Cenozoic era, there were two zones of geosynclinal folding - the Mediterranean and the Pacific, within which sedimentary layers were deposited.
• The mainland Gondwana disintegrates.
• The North American continent and the Eurasian are distinguished.
• In the middle of the Paleogene, the Tethys Ocean extends to part of modern Europe, Siberia, Central Asia, the Arabian Peninsula and the African continent.
• In the Late Paleogene, the sea leaves these platforms.

Life of the Cenozoic era

After the mass extinction of various species, life on Earth has changed dramatically. The place of the dinosaurs is occupied by mammals. Warm-blooded mammals showed better adaptability to the Cenozoic conditions. A new form of life arises - a rational person.

Plants of the cenozoic era

At high latitudes, angiosperms and conifers begin to prevail. The equator zone was covered with rainforests (palm trees, sandalwood, ficus). In the depths of the continental zones, savannas and rare forests were widespread. Tropical plants — breadfruit, tree ferns, banana trees, and sandalwood — grew at mid-latitudes.

The Arctic was covered with deciduous and coniferous trees. In the Neogene, the flora of the modern Mediterranean Sea begins to develop. In the north, there were almost no evergreens. The taiga, tundra and forest-steppe zones stand out. Deserts or semi-deserts appear on the savannah site.

Animals of the cenozoic era

At the beginning of the Cenozoic era, the following prevailed:

• Small mammals
• Proboscis
• Pig-like
• Indicoteric
• Ancestors of horses

The savannah was inhabited by diatrim birds - predators who could not fly. In the Neogene, lions and hyenas are distributed. Main mammals:

Bats, rodents, monkeys, cetaceans, etc.

The largest are rhinos, saber-toothed tigers, dinoteria and mastodon. Placental mammals begin to dominate. Periodic periods of cooling and glaciation lead to the fact that many species disappear.

Aromorphoses of the Cenozoic era

• Brain enlargement in a human ancestor (epimorphosis);
• The formation of a new geological shell of the earth - the noosphere;
• The spread of angiosperms;
• Active development of invertebrates. Insects develop a tracheal system, a cover of chitin, a central nervous system, and unconditioned reflexes develop;
• Vertebrate circulation system evolution.

Climate of the Cenozoic era

The climatic conditions of the Paleocene and Eocene were rather mild. In the equatorial zone, the average air temperature is about 28 0 C. At the latitude of the North Sea - about 22-26 0 C. In the area of \u200b\u200bthe modern northern islands, vegetation corresponded to modern subtropics. Remains of the same type of flora are found in Antarctica.

A sharp cooling occurred during the Oligocene. In the region of the poles, the air temperature dropped to +5 0 С. Signs of glaciation began to appear. Later, the ice sheet of Antarctica appeared. In the Neogene, the climatic conditions were warm and humid. There is a zoning that resembles modern.

• In the Cenozoic era, primates and the first man appear;
• The most recent glaciation was 20,000 years ago, i.e., relatively recently. The total area of \u200b\u200bglaciers was more than 23 million km 2, and the ice thickness was almost 1.5 km;
• Many species of fauna and flora at the beginning and middle of the Cenozoic era are the ancestors of modern times. At the end of the period, the outlines of the oceans and continents become similar to modern ones.

Summary

Continents take on a modern look. The animal and plant world habitual for modern understanding is being formed. Dinosaurs completely disappear. Mammals (placental) develop and angiosperms spread. Animals develop a central nervous system. Alpine folding begins to form and the main mineral deposits appear.

At present, the Cenozoic era continues on Earth. This stage of the development of our planet is relatively short, if we compare it with the previous ones, for example, the Proterozoic or Archean. So far, it is only 65.5 million years.

The geological processes that took place during the Cenozoic formed the modern face of the oceans and continents. Climate gradually changed and, as a result, the plant world in one or another part of the planet. The previous era - the Mesozoic - ended with the so-called Cretaceous catastrophe, which caused the extinction of many species of animals. The beginning of a new era was marked by the fact that empty ecological niches began to fill up again. The development of life in the Cenozoic era occurred rapidly both on land and in water and in the air. The dominant position was occupied by mammals. Finally, the ancestors of man appeared. People turned out to be very “promising” creatures: despite repeated climate changes, they not only survived, but also evolved, spreading throughout the planet. Over time, human activity has become another factor in the transformation of the Earth.

Cenozoic era: periods

Previously, Cenozoic (the “era of new life”) was usually divided into two main periods: tertiary and quaternary. Now another classification is in use. The very first stage of the Cenozoic is the Paleogene (“ancient formation”). It began about 65.5 million years ago and lasted 42 million years. The Paleogene is divided into three subperiods (Paleocene, Eocene and Oligocene).

The next stage is Neogene (“new education”). This era began 23 million years ago, and its duration was approximately 21 million years. The Neogene period is divided into the Miocene and Pliocene. It is important to note that the end of the Pliocene dates from the appearance of the ancestors of man (though, at that time, they did not even remind modern people). Somewhere 2-1.8 million years ago, the anthropogenic, or Quaternary, period began. It continues to this day. Throughout the anthropogenous process, man has been (and is) developing. The sub-periods of this stage are the Pleistocene (the era of glaciation) and the Holocene (post-glacial era).

Climatic conditions of the Paleogene

A long period of the Paleogene opens the Cenozoic era. The climate of the Paleocene and Eocene was mild. In the region of the equator, the average temperature reached 28 ° С. In the North Sea region, the temperature was not much lower (22-26 ° С).

On the territory of Svalbard and Greenland, evidence was found that the plants characteristic of the modern subtropics felt quite comfortable there. Traces of subtropical vegetation are also found in Antarctica. Neither glaciers nor icebergs were in the Eocene yet. On Earth, there were areas that did not lack moisture, regions with a variable-humid climate and arid areas.

During the Oligocene period it sharply became colder. At the poles, the average temperature dropped to 5 ° C. The formation of glaciers began, which later formed the Antarctic ice sheet.

Paleogene Flora

Cenozoic era - the time of widespread dominance of angiosperms and gymnosperms (conifers). The latter grew only in high latitudes. At the equator, rainforests prevailed, the basis of which were palm trees, ficus, and various representatives of sandalwood. The farther from the sea, the drier the climate became: in the depths of the continents spread savannas and light forests.

In the middle latitudes, tropical hygrophilous and temperate plants (tree ferns, breadfruit, sandalwood, banana trees) were common. Closer to high latitudes, the species composition became completely different. A typical subtropical flora is characteristic of these places: myrtle, chestnut, laurel, cypress, oak, thuja, sequoia, araucaria. Plant life in the Cenozoic era (in particular, in the Paleogene era) flourished even beyond the Arctic Circle: in the Arctic, Northern Europe and America, a predominance of coniferous-deciduous deciduous forests was noted. But there were also subtropical plants listed above. The polar night was not an obstacle to their growth and development.

Paleogene fauna

The Cenozoic era fauna provided a unique chance. The fauna has changed dramatically: the dinosaurs were replaced by primitive small mammals that live mainly in forests and swamps. Reptiles and amphibians have become smaller. Dominated by various proboscis animals, indicoteria (similar to rhinos), tapiro and pig-like.

As a rule, many of them were adapted to spend part of the time in water. During the Paleogene period, the ancestors of horses also appear, various rodents, and later - predators (creodonts). Toothless birds nest on the tops of the trees, carnivorous diatrims live in the savannahs - birds that cannot fly.

Great variety of insects. As for the marine fauna, the flowering of cephalopods and bivalves, corals; primitive crayfish, cetaceans appear. The ocean at this time belongs to bony fishes.

Neogene climate

The Cenozoic era continues. The climate in the Neogene era remains relatively warm and rather humid. But the cooling, which began in the Oligocene, makes its own adjustments: glaciers no longer melt, humidity drops, climate continentality increases. By the end of the Neogene, zonality approached the modern one (the same can be said about the outlines of the oceans and continents, as well as the relief of the earth's surface). Pliocene marked the beginning of another cold snap.

Neogene, Cenozoic era: plants

At the equator and in the tropical zones, either savannas or moist forests still prevail. Temperate and high latitudes could boast of the greatest diversity of the plant world: broad-leaved forests, mainly evergreens, were widespread here. As the air became drier, new species appeared, from which the modern Mediterranean flora (olives, plane trees, walnuts, boxwood, southern pine and cedar) gradually developed. In the north, evergreens did not survive. But coniferous-deciduous forests showed a richness of species - from sequoia to chestnut. At the end of the Neogene, such landscape forms as taiga, tundra and forest-steppe appeared. This was again associated with a cooling. North America and Northern Eurasia have become taiga regions. Steppes formed in temperate latitudes with an arid climate. Where savannas used to be, semi-deserts and deserts arose.

Neogene fauna

It would seem that the Cenozoic era is not so long (in comparison with others): flora and fauna, however, managed to change greatly from the beginning of the Paleogene. The dominant mammals are placental. Initially, anchiteria, and then the hipparionic fauna, developed. Both are named after characteristic representatives. Anchiteria is the ancestor of a horse, a small animal with three fingers on each limb. Hipparion is, in fact, a horse, but still three-fingered. It is not necessary to think that only relatives of horses and simply ungulates (deer, giraffes, camels, pigs) belonged to these faunas. In fact, among their representatives were predators (hyenas, lions), and rodents, and even ostriches: life in the Cenozoic era was distinguished by fantastic diversity.

The distribution of these animals was facilitated by an increase in the area of \u200b\u200bsavannahs and steppes.

At the end of the Neogene, the ancestors of man appeared in the forests.

Climate of anthropogen

This period is characterized by an alternation of glaciation and warming. When the glaciers advanced, their lower boundaries reached 40 degrees north latitude. The largest glaciers of that time were concentrated in Scandinavia, the Alps, North America, Eastern Siberia, the Subpolar and Northern Urals.

In parallel with glaciation, the sea was attacking the land, although not as powerful as in the Paleogene. The interglacial periods were characterized by a mild climate and regression (drainage of the seas). Now the next interglacial period is just coming, which should end no later than 1000 years later. After it, another glaciation will occur, which will last about 20 thousand years. But it is not known whether this will actually happen, since human intervention in natural processes provoked climate warming. It’s time to think about whether the Cenozoic will end in an eraglobal environmental disaster?

Flora and fauna of anthropogen

The onset of glaciers caused heat-loving plants to move south. True, mountain ranges interfered with this. As a result, many species did not survive to this day. During glaciations, there were three main types of landscapes: taiga, tundra and forest-steppe with plants characteristic of them. Tropical and subtropical zones narrowed and shifted strongly, but still persisted. In the interglacial periods, broad-leaved forests prevailed on Earth.

As for the fauna, primacy still belonged (and belongs) to mammals. Massive, wool-covered animals (mammoths, woolly rhinos, megaloceros) became the hallmark of the ice ages. Along with them there were bears, wolves, deers, lynxes. All animals as a result of cooling and warming were forced to migrate. Primitive and unadapted were dying out.

The primates continued to develop. Improving the hunting skills of human ancestors can explain the extinction of a number of game animals: giant sloths, horses of North America, mammoths.

Summary

It is not known when the Cenozoic era will end, the periods of which we have considered above. Sixty-five million years by the standards of the universe - quite a bit. However, during this time, continents, oceans and mountain ranges managed to form. Many species of plants and animals became extinct or evolved under the pressure of circumstances. Mammals took the place of dinosaurs. And man turned out to be the most promising of mammals, and the last period of the Cenozoic - the anthropogen - is associated mainly with human activity. It is possible that it depends on us how and when the Cenozoic era ends - the most dynamic and short of earthly eras.

The Cenozoic ice age (30 million years ago - the present) is the recently begun ice age.

Is the present Holocene that has begun? 10,000 years ago, characterized as a relatively warm interval after the Pleistocene ice age, often qualifying as interglacial. Ice sheets exist in the high latitudes of the northern (Greenland) and southern (Antarctica) hemispheres; in the northern hemisphere, the glaciation of Greenland extends southward to 60 ° north latitude (i.e., to the latitude of St. Petersburg), fragments of sea ice cover up to 46-43 ° north latitude (i.e., to latitude Crimea), and permafrost to 52--47 ° north latitude. In the southern hemisphere, the continental part of Antarctica is covered by an ice sheet with a thickness of 2500--2800 m (up to 4800 m in some areas of East Antarctica), while ice shelves make up? 10% of the continent’s area that rises above sea level. In the Cenozoic ice age, the Pleistocene ice age is the strongest: a drop in temperature led to glaciation of the Arctic Ocean and the northern regions of the Atlantic and the Pacific Ocean, while the border of glaciation passed 1500-1700 km south of the present.

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

Fig. 4

* 34 million years ago - the origin of the Antarctic ice sheet

* 25 million years ago - its reduction

* 13 million years ago - its repeated growth

* about 3 million years ago - the beginning of the Pleistocene ice age, the repeated appearance and disappearance of ice sheets in the northern regions of the Earth

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 mainland" of Gondwana continued to split into pieces. South America is now completely cut off from the rest of the world and has become a kind of floating "ark" with a unique fauna of early mammals. Africa, India and Australia have moved even further apart. Throughout the Paleocene, Australia was located near Antarctica. Sea level dropped, and in many parts of the globe new land areas appeared.

Fauna: On land, the age of mammals began. Rodents and insectivores appeared. Among them were large animals, both carnivorous and herbivorous. In the seas, marine reptiles have been replaced by new species of predatory bone fish and sharks. New varieties of bivalve mollusks and foraminifers arose.

Plant World: New species of flowering plants and insects pollinating them continued to spread.

Eocene era (from 55 to 38 million years ago)

Geography and climate: In the Eocene, the main land masses began to gradually take on a position close to the one they occupy today. A significant part of the land was still divided into a kind of gigantic islands, as the vast 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 began to diverge. North America and Europe were also divided, with the emergence of new mountain ranges. The sea flooded part of the land. The climate was warm or temperate everywhere. Lots of tropical vegetation covered most of the area, and vast areas were overgrown with dense swampy forests.

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

Flora: In many parts of the world forests with lush vegetation grew, palms grew in temperate latitudes.

Oligocene era (38 to 25 million years ago)

Geography and climate: In the Oligocene era, India crossed the equator, and Australia finally separated from Antarctica. The climate on Earth became cooler, a huge ice sheet formed over the South Pole. For the formation of such a large amount of ice, no less significant volumes of sea water were required. This led to a decrease in sea level throughout the planet and the expansion of land area. Widespread cooling caused the disappearance of lush tropical forests of the Eocene in many parts of the globe. Their place was taken by forests, which preferred a more temperate (cool) climate, as well as vast steppes, spread over all continents.

Fauna: With the spread of the steppes, the heyday of herbivorous mammals began to flourish. Among them, new species of rabbits, hares, giant sloths, rhinos and other ungulates arose. The first ruminants appeared.

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

Miocene era (from 25 to 5 million years ago)

Geography and climate: Throughout the Miocene, the continents were still "on the march", and a series of grand cataclysms occurred during their collisions. Africa "crashed" into Europe and Asia, resulting in the Alps. In the collision of India and Asia, the Himalayan mountains shot up. At the same time, the Rocky Mountains and the Andes formed, as other giant plates continued to move and crawl onto each other.

However, Austria and South America remained isolated from the rest of the world, and their own unique fauna and flora continued to develop on each of these continents. Glacial cover in the southern hemisphere spread throughout Antarctica, which led to further cooling of the climate.

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

Flora: Inland areas became colder and drier and steppes spread more and more.

Pliocene era (from 5 to 2 million years ago)

Geography and climate: A space traveler, looking at the Earth from above at the beginning of the Pliocene, would find the continents in almost the same places as in our days. Giant ice caps in the northern hemisphere and the huge ice sheet of Antarctica would be visible to the galactic visitor. Because of all this mass of ice, the Earth’s climate has become even cooler, and on the surface of the continents and oceans of our planet it has become much colder. Most of the forests preserved in the Miocene have disappeared, giving way to the immense steppes, spread all over the world.

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

Flora: As the climate cools, the steppes have replaced forests.

Fig.5

Quaternary

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 of the continents occupied the same position as in our days, and some of them needed to cross half the globe for this. A narrow land "bridge" connected North and South America. Australia was located on the opposite side of the earth from Britain. Giant ice sheets crawled into the northern hemisphere. It was an era of great glaciation with alternating periods of cooling and warming and fluctuations in sea level. This ice age continues to this day.

Animal kingdom: Some animals managed to adapt to the intensified colds, having acquired a thick coat: for example, woolly mammoths and rhinos. Of the predators, the most common are saber-toothed cats and cave lions. It was the age of giant marsupials in Australia and huge flightless birds such as moa or epiornis living in many areas of the southern hemisphere. The first humans appeared, and many large mammals began to disappear from the face of the Earth.

Flora: Ice gradually crept from the poles, and coniferous forests gave way to the tundra. Further from the edge of the glaciers, deciduous forests were replaced by conifers. Vast steppes stretch in warmer regions of the globe.

Holocene era (from 0.01 million years to the present)

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

Fauna: At the beginning of the period, many species of animals died out, mainly due to general warming, but, perhaps, increased human hunting for them also affected. Later, they could fall prey 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 the area under crops and pastures. In addition, plants brought by people to areas new to them sometimes replaced native vegetation.

Fig. 6

ice Age Tertiary Quaternary