Archean era. The rocks of the Archean era are represented by highly metamorphosed and dislocated gneisses, metamorphosed shales and igneous rocks. The layer of graphite and graphite schists in the sediments, as well as the presence of recrystallized limestones and marbles, indicates the organogenic-chemical origin of the rocks and the presence of seas at that time.

The absence of organic remains associated with the intensive metamorphism of sedimentary rocks and the wide development of magmatism does not allow us to subdivide the rocks of the Archean era into periods and epochs. The era is characterized by the formation of continents and oceans on Earth, and its duration is 1.8 billion years (Table 2).

Proterozoic era. The deposits of the Proterozoic era are represented mainly by metamorphosed sedimentary and igneous rocks. There are also weakly metamorphosed deposits with traces of vital activity of organisms. The duration of an era is 2.1 billion years.

During the Archean and Proterozoic eras, there were numerous large mining movements accompanied by intense magmatic activity.

Palaeozoic. The duration of an era is 330 million years. The deposits of the Paleozoic era, in contrast to the older ones, are only intensively dislocated and metamorphosed in places. Sedimentary and igneous rocks are widespread. Metamorphic rocks are of subordinate importance.

A wide variety of invertebrates made it possible to divide the era into two suberas: the early Paleozoic and the late Paleozoic. Poders differ greatly from each other in terms of paleontological remains and the results of geological development, which made it possible to divide them into the following periods and eras.

Early Paleozoic 165-170 million years long.

1. Cambrian (subdivided into three epochs - early, middle and late).

2. Ordovician (subdivided into three epochs - early, middle and late).

3. Silurian (subdivided into three epochs - early, middle and late).

Throughout the early Paleozoic, the earth's crust experienced Caledonian era of folding. The beginning of the Caledonian folding refers to the end of the Proterozoic, the end - to the end of the Silurian - the beginning of the Devonian.

At the beginning of the Early Paleozoic, the Caledonian folding manifested itself mainly in the form of subsidence, at the end of the Ordovician and Silurian - uplift earth's crust.

Late Paleozoic lasting 165 million years.

1. Devonian (subdivided into three epochs - early, middle and late).

2. Carboniferous (subdivided into three epochs - early, middle and late).

3. Permian (subdivided into two epochs - early and late).

By the beginning of the Late Paleozoic, ancient platforms and folded belts remain the main structural elements of the earth's crust. The supercontinent Gondwana underwent rifting at the beginning of the Late Paleozoic, the existing structures became more complex, troughs formed, and folded systems turned into platforms. The second half of the Late Paleozoic is characterized by the manifestation of the Hercynian stage of tectogenesis, which formed mountain-fold structures of complex structure.

Mesozoic era 170 million years long. The era includes the Triassic, Jurassic and Cretaceous periods.. The Triassic and Jurassic periods are divided into three epochs each, the Cretaceous - into two.

The beginning of the Mesozoic era is a time of significant changes in the structure of mobile belts. Having experienced the Hercynian tectogenesis, many belts passed into the stage of young platforms, although the fold-geosynclinal regime still continued, but to a lesser extent.

AT triassic active rifting occurred, which affected vast areas of continents and oceans. In the late Triassic era, tectonic processes of compression and deformation of the earth's crust manifested themselves in many places on the planet. From the second half Jurassic and in chalk a significant part of the platforms experienced subsidence and transgression of the sea.

Cenozoic era. The era has a duration of 66 million years and is divided into three periods: Paleogene, Neogene and hquaternary. The periods are divided into epochs: the Paleogene - into three, the Neogene - into two, the Quaternary - into four (early, middle, late and modern). As part of the Quaternary period, divisions are distinguished: glacial and post-glacial. The duration of the Quaternary is 0.7 million years.

In the Cenozoic era, very intense vertical and horizontal movements took place on the continents and in the oceanic plates. The tectonic epoch that manifested itself in the Cenozoic era is called Alpine. It covered almost the entire Earth and differs from the previous ones by a significant amplitude of uplifts: both individual mountain systems and continents and subsidence of intermountain and oceanic depressions, the splitting of continents and oceanic plates and their horizontal movements.

At the beginning of the Cenozoic era, rifting intensified on the continents and in the oceans, the process of plate movement became significantly more active, and the previously inherited spreading of the ocean floor continues. At the end of the Neogene, the modern appearance of continents and oceans was formed on Earth. At the same time and in the Quaternary period, the composition of the organic world changes and its differentiation intensifies, the earth's surface cools, the areas and heights of the continents increase, the areas decrease and the depths of the oceans increase.

As a result of Alpine tectogenesis, Alpine folded structures arose, which are characterized by the manifestation of horizontal displacements, formations in the form of thrusts, overturned folds, covers, etc.

All subdivisions of the geochronological table of period rank - systems are designated by the first letter of the Latin alphabet of the name. Each period (system) has its own color, which is shown on the geological map. These colors are generally accepted and cannot be replaced.

The geochronological scale is the most important document certifying the sequence and time of geological events in the history of the Earth. It must be known without fail and therefore the scale must be learned from the very first steps of studying geology.

The thesis about the evolution of the Earth, as an exceptional object of its kind in the cosmos, occupies the main step. In view of this, geological time becomes a special numerical-evolutionary characteristic. The comprehension of this time is engaged in science, which bears the definition of Geochronology, that is, the geological account of time. The above specialized science is divided into two types: absolute geochronology and relative geochronology.

Absolute geochronology carries out activities to determine the absolute age rocks. This age is transmitted in units of time, namely, in millions of years.

The key link in establishing this age is the rate of decay of isotopes of radioactive components. This speed is extremely constant and is free from the saturation of physical and chemical currents. Age notation is organized in ways that are related to nuclear physics. Minerals, which have radioactive components in their composition, give rise to a closed structure during the device crystal lattices. It is in this structure that the process of accumulation of elements takes place. radioactive decay. Therefore, if you have information about the speed of the presented process, you can find out how old the mineral is. For example, the half-life of radium is about 1590 years. And the final decay of this element will occur in a period of time that is ten times longer than the half-life. Nuclear geochronology has the main methods, namely: lead, potassium-argon, rubidium-strontium and radiocarbon.

It was the presented methods of nuclear geochronology that contributed to the establishment of the age of the planet and the time of eras and periods. At the beginning of the 20th century, P. Curie and E. Rutherford introduced a different method of setting the time, which was called radiological. Relative geochronology carries out the activity of determining the relative age of rocks. That is, which accumulations in the earth's crust are younger and which are ancient.

Relative geochronology specializes in such theses as "early, middle and late age". A number of techniques for identifying the relative age of rocks have scientific justification. These methods can be divided into two groups. These groups are called paleontological and non-paleontological. Paleontological methods occupy a leading position, as they are more multifunctional and are applied on a wide front. Of course, there are exceptions. Such a rare case is the lack of natural accumulations in the rocks. Use the presented method when studying fragments of extinct ancient organisms. It should be noted that each rock layer is characterized by a specific set of natural remains. The Englishman W. Smith discovered a certain chronology in the age characteristics of the breeds. Namely, the higher the layer is, the younger it is in age. Consequently, the content of microorganism residues in it will be an order of magnitude higher. Also, W. Smith owns the first geological map of England. On this map, the scientist divided the rocks by age.

Non-paleontological methods for determining the relative age of rocks are used in cases where there are no organic remains in the rocks under study. In this case, there are stratigraphic, lithological, tectonic and geophysical methods. For example, when using the stratigraphic method, it is possible to establish the chronology of the formation of layers at their standard occurrence, namely, those layers that lie below will be more ancient.

The establishment of the chronology of the formation of rocks is carried out by relative geochronology, while the specific determination of age in units of time is carried out by absolute geochronology. The purpose of geological time is to discover the temporal chronology of geological phenomena.

Geological table

In order to establish the age criteria for rocks, scientists use a wide variety of methods. Therefore, it was expedient to create a highly specialized scale for ease of use. Geological time according to this scale is divided into time intervals. A certain segment is characterized by a specific stage in the structure of the earth's crust and the formation of living organisms. The presented scale has a name - geochronological table. It has such subgroups as eon, era, period, epoch, century, time. It should be noted that each group is characterized by a certain set of savings. Such a collection, in turn, is called a stratigraphic complex, which also has a number of types, namely: eonoteme, group, system, department, stage, zone. For example, the system belongs to the stratigraphic category, and the time group of the geochronological department belongs to its characteristic subgroup, which is called the era. As a consequence, there are two scales: stratigraphic and geochronological. The stratigraphic school is used when accumulations in rocks are studied. Since at any time on the planet any geological processes. The geochronological scale is used to set relative time. Since the scale was approved, its structure has undergone many changes.

To date, the most voluminous stratigraphic category is eonotemes. It is divided into Archean, Proterozoic and Phanerozoic. In the geochronological scale, these classes are subject to categories of diverse activities. Based on the time of existence on Earth, scientists identified two eonotems: Archean and Proterozoic. It is these eonotemes that comprised about eighty percent of the entire time. The remaining Phanerozoic eonoteme is noticeably smaller than the previous eons, since it covered only about five hundred and seventy million years. This eonoteme is divided into three main classes: Paleozoic, Mesozoic and Cenozoic.

The names of eonotems and classes come from the Greek language:

• Archeos - the most ancient;
• Proteros - primary;
• Paleos - ancient;
• Mezos - medium;
• Kainos - new;

From the word form "zoikos", which has the definition of "life", the word "zoi" was formed. Based on this word formation, scientists have identified the era of life on Earth. For example, the Paleozoic era means the era of ancient life.

Eras and periods

Based on the geochronological table, experts divided the history of the planet into five geological eras. The above eras received the following names: Archean, Proterozoic, Paleozoic, Mesozoic, Cenozoic. Also, era data is divided into periods. The number of these time intervals is equal to twelve, which apparently exceeds the number of eras. The time span of these stages is from twenty to one hundred million years. The last period of the Cenozoic era is not completed, since its time period is about two million years.

Archean era. This era began its existence after the formation and structuring of the earth's crust on the planet. By this time period, there were already rocks on the planet and the processes of erosion and accumulation of precipitation had begun. This era lasted for about two billion years. It is the Archean era that scientists consider the longest in time. During its course, volcanic processes were active on the planet, depths were raised, which contributed to the formation of mountains. Unfortunately, most of fossils were destroyed, but some general data about this era still survived. In the rocks that existed in the Archean era, scientists have found pure carbon. Experts believe that these are modified remains of living organisms. In view of the fact that the amount of graphite indicates the amount of living matter, there was quite a lot of it in this era.

Proterozoic era. According to the time characteristic, this is the next period, which contains one billion years. During this epoch, precipitation accumulated and one global glaciation occurred. Fossils that were found in the mountain strata of this time are the main witnesses that life existed and went through stages of evolution. The remains of jellyfish, mushrooms, algae and much more were found in the rock layers.

Palaeozoic. This era is divided into six time periods:

• Cambrian;
• Ordovician;
• Silur;
• Devonian;
• Carbon/Coal;
• Perm / Perm;

The time period of the Paleozoic era covers three hundred and seventy million years. During this period, representatives of all classes of the animal world appeared. Only birds and mammals were missing.

Mesozoic era. Experts have identified three stages:

• Triassic;

This period covers a time span of one hundred and sixty-seven million years. During the first two periods, the main part of the continents carried out a rise above sea level. Climatic conditions gradually changed and became warmer. There is a popular stone forest in Arizona that has existed since the Triassic period. During the last period, a gradual rise of the sea occurs. North American Continent completely immersed in water, as a result of which, the Gulf of Mexico connected with the Arctic basin. The end of the Cretaceous period is characterized by the fact that large uplifts of the earth's crust occurred. So the Rocky Mountains, the Alps, the Himalayas, the Andes appeared.

Cenozoic era. This period continues to this day. Experts divide it into three periods:

• Paleogene;
• Neogene;
• Quaternary;

The last period is characterized by special features. During this period, the final formation of the planet took place. New Guinea and Australia have separated. The two Americas have merged. This time period was identified by J. Denoyer in 1829. main feature is that a man has appeared.

It is during this period that all of humanity lives today.

Geological table- this is one of the ways to represent the stages of development of the planet Earth, in particular life on it. The table records eras, which are subdivided into periods, their age, duration are indicated, the main aromorphoses of flora and fauna are described.

Often in geochronological tables, earlier, i.e. older, eras are written at the bottom, and later, i.e., younger ones, at the top. Below are data on the development of life on Earth in the natural chronological order: from old to new. Tabular form omitted for convenience.

Archean era

It began about 3500 million (3.5 billion) years ago. Lasted about 1000 million years (1 billion).

In the Archean era, the first signs of life on Earth appear - single-celled organisms.

According to modern estimates, the age of the Earth is more than 4 billion years. Before the Archean, there was the Catharchean era, when there was no life yet.

Proterozoic era

It began about 2700 million (2.7 billion) years ago. It lasted more than 2 billion years.

Proterozoic - the era of early life. In the layers belonging to this era, rare and few organic remains are found. However, they belong to all types of invertebrates. It is also likely that the first chordates appear - non-cranial.

Palaeozoic

It began about 570 million years ago and lasted more than 300 million years.

Paleozoic - ancient life. Starting from it, the process of evolution is better studied, since the remains of organisms from the upper geological layers are more accessible. Hence, it is customary to consider each era in detail, noting the changes in the organic world for each period (although their periods are distinguished both in the Archean and in the Proterozoic).

Cambrian Period (Cambrian)

Lasted about 70 million years. Marine invertebrates and algae thrive. Many new groups of organisms appear - the so-called Cambrian explosion occurs.

Ordovician period (Ordovician)

Lasted 60 million years. The heyday of trilobites, racoscorpions. The first vascular plants appear.

Silurian (30 Ma)

• Bloom of corals.
• The appearance of scutellum - jawless vertebrates.
• The appearance of psilophyte plants that have come to land.

Devonian (60 Ma)

• The flowering of corymbs.
• The appearance of lobe-finned fish and stegocephalians.
• Distribution on land of higher spores.

Carboniferous period

Lasted about 70 million years.

• The rise of amphibians.
• Appearance of the first reptiles.
• The emergence of flying forms of arthropods.
• Decline in the number of trilobites.
• Blossoming ferns.
• The emergence of seed ferns.

Perm (55 million)

• The spread of reptiles, the emergence of animal-toothed lizards.
• Trilobite extinction.
• Disappearance of coal forests.
• Distribution of gymnosperms.

Mesozoic era

The era of middle life. It began 230 million years ago and lasted about 160 million years.

Triassic

Duration - 35 million years. The flowering of reptiles, the appearance of the first mammals and true bony fish.

Jurassic period

Lasted about 60 million years.

• Dominance of reptiles and gymnosperms.
• Appearance of Archeopteryx.
• There are many cephalopods in the seas.

Cretaceous period (70 million years)

• The emergence of higher mammals and true birds.
• Widespread distribution of bony fish.
• Reduction of ferns and gymnosperms.
• The emergence of angiosperms.

Cenozoic era

The era of new life. It began 67 million years ago, lasts, respectively, the same amount.

Paleogene

Lasted about 40 million years.

• Appearance of tailed lemurs, tarsiers, parapithecus and dryopithecus.
• An explosion of insects.
• The extinction of large reptiles continues.
• Entire groups of cephalopods are disappearing.
• dominance of angiosperms.

Neogene (about 23.5 Ma)

dominance of mammals and birds. The first representatives of the genus Homo appeared.

Anthropogene (1.5 Ma)

Appearance of Homo sapiens species. The animal and plant world takes on a modern look.

The periods of the geological history of the Earth are the epochs, the successive change of which formed it as a planet. At this time, mountains formed and collapsed, seas appeared and dried up, ice ages succeeded each other, and the evolution of the animal world took place. The study of the geological history of the Earth is carried out on sections of rocks that have retained the mineral composition of the period that formed them.

Cenozoic period

The current period of the geological history of the Earth is the Cenozoic. It began sixty-six million years ago and continues to go on. The conditional boundary was drawn by geologists at the end of the Cretaceous period, when a mass extinction of species was observed.

The term was proposed by the English geologist Phillips in the middle of the nineteenth century. Its literal translation sounds like " new life". The era is divided into three periods, each of which, in turn, is divided into eras.

Geological periods

Any geological era is divided into periods. There are three periods in the Cenozoic era:

Paleogene;

Quaternary period of the Cenozoic era, or anthropogen.

In earlier terminology, the first two periods were combined under the name "Tertiary period".

On land, which has not yet had time to finally divide into separate continents, mammals reigned. There were rodents and insectivores, early primates. In the seas, reptiles have been replaced by predatory fish and sharks, and new species of mollusks and algae have appeared. Thirty-eight million years ago, the diversity of species on Earth was amazing, the evolutionary process affected representatives of all kingdoms.

Only five million years ago, the first great apes began to walk on land. Three million years later, on the territory belonging to modern Africa, Homo erectus began to gather in tribes, collect roots and mushrooms. Ten thousand years ago appeared modern man who began to reshape the Earth to suit his needs.

Paleography

The Paleogene lasted forty-three million years. continents in their modern form were still part of Gondwana, which was beginning to split into separate fragments. First in free swimming left South America, which became a reservoir for unique plants and animals. In the Eocene era, the continents gradually occupy their present position. Antarctica is separating from South America and India is moving closer to Asia. An array of water appeared between North America and Eurasia.

In the Oligocene era, the climate becomes cool, India finally consolidates below the equator, and Australia drifts between Asia and Antarctica, moving away from both. Due to temperature changes, ice caps form at the South Pole, which leads to a decrease in sea levels.

In the Neogene period, the continents begin to collide with each other. Africa "rams" Europe, resulting in the Alps, India and Asia forms Himalayan mountains. In the same way, the Andes and rocky mountains appear. In the Pliocene era, the world becomes even colder, forests die out, giving way to steppes.

Two million years ago, a period of glaciation sets in, sea levels fluctuate, white caps at the poles either rise or melt again. The animal and plant world is being tested. Today, humanity is experiencing one of the stages of warming, but in global scale the ice age continues.

Life in the Cenozoic

The Cenozoic periods cover a relatively short period of time. If you put the entire geological history of the earth on the dial, then the last two minutes will be allotted for the Cenozoic.

The extinction event that marked the end of the Cretaceous and the beginning new era, erased from the face of the Earth all animals that were larger than a crocodile. Those who managed to survive were able to adapt to new conditions or evolved. The drift of the continents continued until the appearance of people, and on those of them that were isolated, a unique animal and plant world could be preserved.

The Cenozoic era was distinguished by a large species diversity of flora and fauna. It is called the time of mammals and angiosperms. In addition, this era can be called the era of the steppes, savannahs, insects and flowering plants. The crown of the evolutionary process on Earth can be considered the appearance of Homo sapiens.

Quaternary period

Modern humanity lives in the Quaternary era of the Cenozoic era. It began two and a half million years ago, when in Africa, anthropoid primates began to stray into tribes and get their own food by picking berries and digging up roots.

The Quaternary period was marked by the formation of mountains and seas, the movement of continents. The earth has acquired the form it has now. For geologists, this period is just a stumbling block, since its duration is so short that the methods of radioisotope scanning of rocks are simply not sensitive enough and give out large errors.

The characteristic of the Quaternary period is made up of materials obtained by radiocarbon analysis. This method is based on measuring the amount of rapidly decaying isotopes in soil and rocks, as well as bones and tissues of extinct animals. The entire period of time can be divided into two epochs: Pleistocene and Holocene. Humanity is now in the second age. While there are no exact calculations when it will end, but scientists continue to build hypotheses.

Pleistocene Epoch

The Quaternary period opens the Pleistocene. It began two and a half million years ago and ended only twelve thousand years ago. It was ice age. Long ice ages were interspersed with short warming periods.

One hundred thousand years ago, a thick ice cap appeared in the area of ​​\u200b\u200bmodern Northern Europe, which began to spread into different sides, absorbing more and more new territories. Animals and plants were forced to either adapt to new conditions or die. The frozen desert stretches from Asia to North America. In some places, the thickness of the ice reached two kilometers.

The beginning of the Quaternary period turned out to be too harsh for the creatures that inhabited the earth. They are accustomed to warm temperate climate. In addition, ancient people began to hunt animals, who had already invented the stone ax and other hand tools. Entire species of mammals, birds and representatives of marine fauna are disappearing from the face of the Earth. Could not stand the harsh conditions and the Neanderthal. The Cro-Magnons were more hardy, successful in hunting, and it was their genetic material should have survived.

Holocene epoch

The second half of the Quaternary period began twelve thousand years ago and continues to this day. It is characterized by relative warming and climate stabilization. The beginning of the era was marked by the mass extinction of animals, and it continued with the development of human civilization, its technical flourishing.

Changes in the animal and plant composition throughout the epoch were insignificant. Mammoths finally died out, some species of birds and marine mammals ceased to exist. About seventy years ago, the general temperature on the earth increased. Scientists attribute this to the fact that human industrial activity causes global warming. In this regard, glaciers in North America and Eurasia have melted, and the ice cover of the Arctic is disintegrating.

ice Age

The Ice Age is a stage in the geological history of the planet, which takes several million years, during which there is a decrease in temperature and an increase in the number of continental glaciers. As a rule, glaciations alternate with warmings. Now the Earth is in a period of relative increase in temperature, but this does not mean that in half a millennium the situation cannot change dramatically.

At the end of the nineteenth century, the geologist Kropotkin visited the Lena gold mines with an expedition and discovered signs of ancient glaciation there. He was so interested in the finds that he took up large-scale international work in this direction. First of all, he visited Finland and Sweden, as he suggested that it was from there that the ice caps spread to Eastern Europe and Asia. Kropotkin's reports and his hypotheses regarding the modern ice age formed the basis contemporary ideas about this period of time.

History of the Earth

The ice age in which the Earth is now is far from the first in our history. The cooling of the climate has happened before. It was accompanied by significant changes in the relief of the continents and their movement, and also influenced the species composition of flora and fauna. Between glaciations there could be intervals of hundreds of thousands and millions of years. Each ice age is divided into glacial epochs or glacials, which during the period alternate with interglacials - interglacials.

There are four ice ages in the history of the Earth:

Early Proterozoic.

Late Proterozoic.

Paleozoic.

Cenozoic.

Each of them lasted from 400 million to 2 billion years. This suggests that our ice age has not even reached its equator yet.

Cenozoic Ice Age

Quaternary animals were forced to grow extra fur or seek shelter from ice and snow. The climate on the planet has changed again.

The first epoch of the Quaternary period was characterized by cooling, and in the second, a relative warming set in, but even now, in the most extreme latitudes and at the poles, the ice cover remains. It covers the territory of the Arctic, Antarctica and Greenland. The thickness of the ice varies from two thousand meters to five thousand.

The strongest in the entire Cenozoic era is the Pleistocene ice age, when the temperature dropped so much that three of the five oceans on the planet froze.

Chronology of the Cenozoic glaciations

The glaciation of the Quaternary period began recently, if we consider this phenomenon in relation to the history of the Earth as a whole. It is possible to distinguish separate epochs during which the temperature dropped especially low.

1. The end of the Eocene (38 million years ago) - the glaciation of Antarctica.
2. The entire Oligocene.
3. Middle Miocene.
4. Middle Pliocene.
5. Glacial Gilbert, freezing of the seas.
6. Continental Pleistocene.
7. Late Upper Pleistocene (about ten thousand years ago).

This was the last major period when, due to the cooling of the climate, animals and humans had to adapt to new conditions in order to survive.

Paleozoic Ice Age

During the Paleozoic era, the Earth was so frozen that ice caps reached Africa and South America in the south, and also covered all of North America and Europe. Two glaciers almost converged along the equator. The peak is considered to be the moment when a three-kilometer layer of ice towered over the territory of northern and western Africa.

Scientists have discovered the remains and effects of glacial deposits during research in Brazil, Africa (in Nigeria) and the mouth of the Amazon River. Thanks to radioisotope analysis, it was found that age and chemical composition these findings are the same. This means that it can be argued that the rock layers were formed as a result of one global process that affected several continents at once.

Planet Earth is still very young by cosmic standards. She is just starting her journey in the universe. It is not known whether it will continue with us or humanity will simply become an insignificant episode in successive geological epochs. If you look at the calendar, we spent a negligible amount of time on this planet, and destroying us with another cold snap is quite simple. People need to remember this and not exaggerate their role in biological system Earth.

We present to your attention an article about the classical understanding of the development of our planet Earth, written not boringly, clearly and not too long… .

At first there was nothing. In the boundless outer space there was only a gigantic cloud of dust and gases. It can be assumed that from time to time through this substance at great speed rushed spaceships with representatives of the universal mind. The humanoids boredly looked out of the windows and did not even remotely guess that in a few billion years intelligence and life would arise in these places.

The gas and dust cloud eventually transformed into solar system. And after the luminary appeared, the planets appeared. One of them was our native land. It happened 4.5 billion years ago. It is from those distant times that the age of the blue planet is counted, thanks to which we exist in this world.

The entire history of the Earth is divided into two huge time periods

• The first stage is characterized by the absence of complex living organisms. There were only single-celled bacteria that settled on our planet about 3.5 billion years ago.
• The second stage began about 540 million years ago. This is the time when living multicellular organisms settled on the Earth. This refers to both plants and animals. Moreover, both seas and land became their habitat. The second period continues to this day, and its crown is man.

Such huge time steps are called eons. Each eon has its own eonoteme. The latter represents a certain stage in the geological development of the planet, which is fundamentally different from other stages in the lithosphere, hydrosphere, atmosphere, and biosphere. That is, each eonoteme is strictly specific and not similar to others.

There are 4 aeons in total. Each of them, in turn, is subdivided into eras of the development of the Earth, and those are divided into periods. This shows that there is a rigid gradation of large time intervals, and the geological development of the planet is taken as the basis.

catarchean

The most ancient eon is called Katarchaeus. It began 4.6 billion years ago and ended 4 billion years ago. Thus, its duration was 600 million years. Time is very ancient, so it was not divided into eras or periods. At the time of the Katarchean, there was neither the earth's crust nor the core. The planet was a cold cosmic body. The temperature in its bowels corresponded to the melting point of the substance. From above, the surface was covered with regolith, like the lunar surface in our time. The relief was almost flat due to constant powerful earthquakes. Naturally, there was no atmosphere and oxygen.

archaeus

The second aeon is called Archaea. It began 4 billion years ago and ended 2.5 billion years ago. Thus, it lasted 1.5 billion years. It is divided into 4 eras:

• eoarchean
• paleoarchaean
• mesoarchean
• neoarchean

Eoarchean(4–3.6 billion years) lasted 400 million years. This is the period of formation of the earth's crust. A huge number of meteorites fell on the planet. This is the so-called Late Heavy Bombardment. It was at that time that the formation of the hydrosphere began. Water appeared on Earth. In large quantities, comets could bring it. But the oceans were still far away. There were separate reservoirs, and the temperature in them reached 90 ° Celsius. The atmosphere was characterized high content carbon dioxide and low nitrogen content. There was no oxygen. At the end of this era of Earth evolution, the first supercontinent Vaalbara began to form.

paleoarchaean(3.6–3.2 billion years) lasted 400 million years. In this era, the formation of the solid core of the Earth was completed. There was a strong magnetic field. His tension was half the current. Consequently, the surface of the planet received protection from the solar wind. This period also includes primitive life forms in the form of bacteria. Their remains, which are 3.46 billion years old, have been found in Australia. Accordingly, the oxygen content in the atmosphere began to increase, due to the activity of living organisms. The formation of Vaalbar continued.

Mesoarchean(3.2–2.8 billion years) lasted 400 million years. Most notable was the existence of cyanobacteria. They are capable of photosynthesis and release oxygen. The formation of a supercontinent has been completed. By the end of the era, it had split. There was also a fall of a huge asteroid. A crater from it still exists on the territory of Greenland.

neoarchean(2.8–2.5 billion years) lasted 300 million years. This is the time of formation of the real earth's crust - tectogenesis. Bacteria continued to grow. Traces of their life are found in stromatolites, whose age is estimated at 2.7 billion years. These lime deposits were formed by huge colonies of bacteria. They were found in Australia and South Africa. Photosynthesis continued to improve.

With the end of the Archean, the eras of the Earth were continued in the Proterozoic eon. This is a period of 2.5 billion years - 540 million years ago. It is the longest of all eons on the planet.

Proterozoic

The Proterozoic is divided into 3 eras. The first is called Paleoproterozoic(2.5–1.6 billion years). It lasted 900 million years. This huge time interval is divided into 4 periods:

• siderium (2.5–2.3 billion years)
• riasian (2.3–2.05 billion years)
• orosirium (2.05–1.8 billion years)
• staters (1.8–1.6 billion years)

siderius remarkable in the first place oxygen catastrophe. It happened 2.4 billion years ago. It is characterized by a radical change in the Earth's atmosphere. In her in huge number free oxygen appeared. Prior to this, the atmosphere was dominated by carbon dioxide, hydrogen sulfide, methane and ammonia. But as a result of photosynthesis and the extinction of volcanic activity at the bottom of the oceans, oxygen filled the entire atmosphere.

Oxygen photosynthesis is characteristic of cyanobacteria, which bred on Earth 2.7 billion years ago. Prior to this, archaebacteria dominated. They do not produce oxygen during photosynthesis. In addition, at first oxygen was spent on the oxidation of rocks. AT large quantities it accumulated only in biocenoses or bacterial mats.

In the end, the moment came when the surface of the planet was oxidized. And the cyanobacteria continued to release oxygen. And it began to accumulate in the atmosphere. The process has accelerated due to the fact that the oceans also stopped absorbing this gas.

As a result, anaerobic organisms died, and they were replaced by aerobic ones, that is, those in which energy synthesis was carried out through free molecular oxygen. The planet was enveloped by the ozone layer and decreased Greenhouse effect. Accordingly, the boundaries of the biosphere expanded, and sedimentary and metamorphic rocks turned out to be completely oxidized.

All these metamorphoses led to Huron glaciation, which lasted 300 million years. It began in the siderium, and ended at the end of the riasian 2 billion years ago. The next Orosirium period notable for intensive mountain building processes. At this time, 2 huge asteroids fell on the planet. The crater from one is called Vredefort and is located in South Africa. Its diameter reaches 300 km. Second crater Sudbury is located in Canada. Its diameter is 250 km.

Last statheric period notable for the formation of the supercontinent Columbia. It included almost all the continental blocks of the planet. There was a supercontinent 1.8-1.5 billion years ago. At the same time, cells were formed that contained nuclei. That is eukaryotic cells. It was very milestone evolution.

The second era of the Proterozoic is called mesoproterozoic(1.6–1 billion years). Its duration was 600 million years. It is divided into 3 periods:

• potassium (1.6–1.4 billion years)
• exatian (1.4–1.2 billion years)
• stenii (1.2–1 billion years).

During such an era of the Earth's development as potassium, the supercontinent Columbia disintegrated. And during the time of exatia, red multicellular algae appeared. This is indicated by a fossil find on the Canadian island of Somerset. Its age is 1.2 billion years. A new supercontinent, Rodinia, formed in the walls. It arose 1.1 billion years ago, and broke up 750 million years ago. Thus, by the end of the Mesoproterozoic, there was 1 supercontinent and 1 ocean on Earth, which was called Mirovia.

The last era of the Proterozoic is called neoproterozoic(1 billion–540 million years). It includes 3 periods:

• thonium (1 billion–850 million years)
• cryogenian (850–635 Ma)
• Ediacaran (635–540 Ma)

During the time of Toni, the disintegration of the supercontinent Rodinia began. This process ended in cryogeny, and the Pannotia supercontinent began to form from 8 separate pieces of land formed. Cryogeny is also characterized by complete glaciation of the planet (Snowball Earth). The ice reached the equator, and after they receded, the process of evolution of multicellular organisms sharply accelerated. The last period of the Neoproterozoic Ediacaran is notable for the appearance of soft-bodied creatures. These multicellular animals are called vendobionts. They were branching tubular structures. This ecosystem is considered the oldest.

Life on Earth originated in the ocean

Phanerozoic

Approximately 540 million years ago, the time of the 4th and last eon, the Phanerozoic, began. There are 3 very important eras of the Earth here. The first is called Paleozoic(540–252 Ma). It lasted 288 million years. It is divided into 6 periods:

• Cambrian (540–480 Ma)
• Ordovician (485–443 Ma)
• Silurian (443–419 Ma)
• Devonian (419–350 Ma)
• Carboniferous (359–299 Ma)
• Permian (299–252 Ma)

Cambrian considered the lifetime of trilobites. These are marine animals that look like crustaceans. Together with them, jellyfish, sponges and worms lived in the seas. This abundance of living beings is called Cambrian explosion. That is, there was nothing like this before, and suddenly it suddenly appeared. Most likely, it was in the Cambrian that mineral skeletons began to emerge. Previously, the living world had soft bodies. They, of course, did not survive. Therefore, complex multicellular organisms of more ancient eras cannot be detected.

The Paleozoic is notable for the rapid spread of organisms with hard skeletons. From vertebrates, fish, reptiles and amphibians appeared. AT flora at first, algae predominated. During Silurian plants began to colonize the land. At the beginning Devonian swampy shores are overgrown with primitive representatives of the flora. These were psilophytes and pteridophytes. Plants reproduced by spores carried by the wind. Plant shoots developed on tuberous or creeping rhizomes.

Plants began to develop land in the Silurian period

There were scorpions, spiders. The real giant was the Meganevra dragonfly. Its wingspan reached 75 cm. bony fish Acanthodes are considered. They lived during the Silurian period. Their bodies were covered with dense diamond-shaped scales. AT carbon, which is also called the Carboniferous period, the most diverse vegetation flourished on the shores of the lagoons and in countless swamps. It was its remains that served as the basis for the formation of coal.

This time is also characterized by the beginning of the formation of the supercontinent Pangea. It was fully formed in the Permian period. And it broke up 200 million years ago into 2 continents. These are the northern continent of Laurasia and the southern continent of Gondwana. Subsequently, Laurasia split, and formed Eurasia and North America. And from Gondwana arose South America, Africa, Australia and Antarctica.

On the Permian accounted for frequent changes climate. Dry times gave way to wet ones. At this time, lush vegetation appeared on the banks. Typical plants were cordaites, calamites, tree and seed ferns. Mesosaurus lizards appeared in the water. Their length reached 70 cm. But by the end of the Permian period, early reptiles died out and gave way to more developed vertebrates. Thus, in the Paleozoic, life reliably and densely settled on the blue planet.

Of particular interest to scientists are the following eras of the Earth's development. 252 million years ago mesozoic. It lasted 186 million years and ended 66 million years ago. Consisted of 3 periods:

• Triassic (252–201 Ma)
• Jurassic (201–145 Ma)
• Cretaceous (145–66 Ma)

The border between the Permian and the Triassic period is characterized by the mass extinction of animals. Died 96% marine species and 70% of terrestrial vertebrates. The biosphere was inflicted very swipe and it took a very long time to recover. And it all ended with the appearance of dinosaurs, pterosaurs and ichthyosaurs. These sea and land animals were of enormous size.

But the main tectonic event of those years - the collapse of Pangea. A single supercontinent, as already mentioned, was divided into 2 continents, and then broke up into those continents that we know now. The Indian subcontinent also broke away. Subsequently, it connected with the Asian plate, but the collision was so violent that the Himalayas were created.

Such nature was in the early Cretaceous period

The Mesozoic is notable for being considered the warmest period of the Phanerozoic eon.. This time global warming. It began in the Triassic and ended at the end of the Cretaceous. For 180 million years, even in the Arctic there were no stable pack glaciers. Heat spread evenly throughout the planet. At the equator, the average annual temperature corresponded to 25-30 ° Celsius. The polar regions were characterized by a moderately cool climate. In the first half of the Mesozoic, the climate was dry, while the second half was characterized by humid. It was at this time that the equatorial climatic zone was formed.

In the animal world, mammals arose from a subclass of reptiles. It was related to improvement. nervous system and the brain. The limbs moved from the sides under the body, the reproductive organs became more perfect. They ensured the development of the embryo in the mother's body, followed by feeding it with milk. A woolen cover appeared, blood circulation and metabolism improved. The first mammals appeared in the Triassic, but they could not compete with dinosaurs. Therefore, for more than 100 million years, they occupied a dominant position in the ecosystem.

The last era is Cenozoic(beginning 66 million years ago). This is the current geological period. That is, we all live in the Cenozoic. It is divided into 3 periods:

• Paleogene (66–23 Ma)
• Neogene (23–2.6 million years)
• the modern Anthropogen or Quaternary period, which began 2.6 million years ago.

There are 2 major events in the Cenozoic. The mass extinction of dinosaurs 65 million years ago and the general cooling on the planet. The death of animals is associated with the fall of a huge asteroid with a high content of iridium. Diameter cosmic body reached 10 km. This resulted in the formation of a crater. Chicxulub with a diameter of 180 km. It is located on the Yucatan Peninsula in Central America.

Earth's surface 65 million years ago

After the fall, there was an explosion of great force. Dust rose into the atmosphere and covered the planet from sun rays. average temperature fell 15°. Dust hung in the air for a whole year, which led to a sharp cooling. And since the Earth was inhabited by large heat-loving animals, they died out. Only small representatives of the fauna remained. It was they who became the ancestors of the modern animal world. This theory is based on iridium. The age of its layer in geological deposits corresponds exactly to 65 million years.

During the Cenozoic, the continents diverged. Each of them formed its own unique flora and fauna. The diversity of marine, flying and land animals has increased significantly in comparison with the Paleozoic. They have become much more advanced, and mammals have taken the dominant position on the planet. In the plant world, higher angiosperms appeared. This is the presence of a flower and an ovule. There were also cereal crops.

The most important thing in the last era is anthropogen or Quaternary, which began 2.6 million years ago. It consists of 2 epochs: the Pleistocene (2.6 million years - 11.7 thousand years) and the Holocene (11.7 thousand years - our time). During the Pleistocene era mammoths, cave lions and bears, marsupial lions, saber-toothed cats and many other animal species that became extinct at the end of the era lived on Earth. 300 thousand years ago, a man appeared on the blue planet. It is believed that the first Cro-Magnons chose for themselves the eastern regions of Africa. At the same time, Neanderthals lived on the Iberian Peninsula.

Notable for the Pleistocene and Ice Ages. For a whole 2 million years, very cold and warm periods of time alternated on Earth. Over the past 800 thousand years, there have been 8 ice ages with an average duration of 40 thousand years. In cold times, glaciers advanced on the continents, and receded in interglacials. At the same time, the level of the World Ocean was rising. About 12 thousand years ago, already in the Holocene, another ice age ended. The climate became warm and humid. Thanks to this, humanity has settled all over the planet.

The Holocene is an interglacial. It has been going on for 12 thousand years. Human civilization has been developing for the last 7 thousand years. The world has changed in many ways. Significant transformations, thanks to the activities of people, have undergone flora and fauna. Today, many animal species are on the verge of extinction. Man has long considered himself the ruler of the world, but the eras of the Earth have not disappeared. Time continues its steady course, and the blue planet conscientiously revolves around the Sun. In a word, life goes on, but what will happen next - the future will show.