Eras of the earth. Geological periods of the Phanerozoic History of the development of life

Life on Earth began over 3.5 billion years ago, immediately after the completion of the formation of the earth's crust. Throughout time, the emergence and development of living organisms influenced the formation of relief and climate. Also, tectonic and climatic changes that occurred over many years influenced the development of life on Earth.

A table of the development of life on Earth can be compiled based on the chronology of events. The entire history of the Earth can be divided into certain stages. The largest of them are eras of life. They are divided into eras, eras into epochs, epochs into centuries.

Eras of life on Earth

The entire period of the existence of life on Earth can be divided into 2 periods: the Precambrian, or cryptozoic (primary period, 3.6 to 0.6 billion years), and the Phanerozoic.

The Cryptozoic includes the Archean (ancient life) and Proterozoic (primary life) eras.

The Phanerozoic includes the Paleozoic (ancient life), Mesozoic (middle life) and Cenozoic (new life) eras.

These 2 periods of life development are usually divided into smaller ones - eras. The boundaries between eras are global evolutionary events, extinctions. In turn, eras are divided into periods, and periods into epochs. The history of the development of life on Earth is directly related to changes in the earth’s crust and the planet’s climate.

Eras of development, countdown

The most significant events are usually identified in special time intervals - eras. Time is counted down in reverse order, from ancient life to modern life. There are 5 eras:

Archean.
Proterozoic.
Paleozoic.
Mesozoic.
Cenozoic.

Periods of development of life on Earth

The Paleozoic, Mesozoic and Cenozoic eras include periods of development. These are smaller periods of time compared to eras.

Palaeozoic:

Cambrian (Cambrian).
Ordovician.
Silurian (Silurian).
Devonian (Devonian).
Carboniferous (carbon).
Perm (Perm).

Mesozoic era:

Triassic (Triassic).
Jurassic (Jurassic).
Cretaceous (chalk).

Cenozoic era:

Lower Tertiary (Paleogene).
Upper Tertiary (Neogene).
Quaternary, or Anthropocene (human development).

The first 2 periods are included in the Tertiary period lasting 59 million years.

Table of the development of life on Earth

Era, period	Duration	Live nature	Inanimate nature, climate
Archean era (ancient life)	3.5 billion years	The appearance of blue-green algae, photosynthesis. Heterotrophs	The predominance of land over the ocean, the minimum amount of oxygen in the atmosphere.
Proterozoic era (early life)	2.7 billion years	The appearance of worms, mollusks, the first chordates, soil formation.	The land is a rocky desert. Accumulation of oxygen in the atmosphere.
The Paleozoic era includes 6 periods:
1. Cambrian (Cambrian)	535-490 Ma	Development of living organisms.	Hot climate. The land is deserted.
2. Ordovician	490-443 Ma	The appearance of vertebrates.	Almost all platforms are flooded with water.
3. Silurian (Silurian)	443-418 Ma	Exit of plants to land. Development of corals, trilobites.	with the formation of mountains. The seas dominate the land. The climate is varied.
4. Devonian (Devonian)	418-360 Ma	The appearance of mushrooms and lobe-finned fish.	Formation of intermountain depressions. Prevalence of dry climate.
5. Coal (carbon)	360-295 Ma	The appearance of the first amphibians.	Subsidence of continents with flooding of territories and the emergence of swamps. There is a lot of oxygen and carbon dioxide in the atmosphere.
6. Perm (Perm)	295-251 Ma	Extinction of trilobites and most amphibians. The beginning of the development of reptiles and insects.	Volcanic activity. Hot climate.
The Mesozoic era includes 3 periods:
1. Triassic (Triassic)	251-200 million years	Development of gymnosperms. The first mammals and bony fish.	Volcanic activity. Warm and sharply continental climate.
2. Jurassic (Jurassic)	200-145 million years	The emergence of angiosperms. Distribution of reptiles, appearance of the first bird.	Mild and warm climate.
3. Cretaceous (chalk)	145-60 million years	The appearance of birds and higher mammals.	Warm climate followed by cooling.
The Cenozoic era includes 3 periods:
1. Lower Tertiary (Paleogene)	65-23 million years	The rise of angiosperms. The development of insects, the emergence of lemurs and primates.	Mild climate with distinct climatic zones.
2. Upper Tertiary (Neogene)	23-1.8 million years	The appearance of ancient people.	Dry climate.
3. Quaternary or Anthropocene (human development)	1.8-0 Ma	The appearance of man.	Cold weather.

Development of living organisms

The table of the development of life on Earth involves division not only into time periods, but also into certain stages of the formation of living organisms, possible climate changes (ice age, global warming).

Archean era. The most significant changes in the evolution of living organisms are the appearance of blue-green algae - prokaryotes capable of reproduction and photosynthesis, and the emergence of multicellular organisms. The appearance of living protein substances (heterotrophs) capable of absorbing organic substances dissolved in water. Subsequently, the appearance of these living organisms made it possible to divide the world into plant and animal.

Mesozoic era.

Triassic. Distribution of plants (gymnosperms). Increase in the number of reptiles. The first mammals, bony fish.
Jurassic period. The predominance of gymnosperms, the emergence of angiosperms. The appearance of the first bird, the flourishing of cephalopods.
Cretaceous period. Distribution of angiosperms, decline of other plant species. Development of bony fishes, mammals and birds.

Cenozoic era.
- Lower Tertiary period (Paleogene). The rise of angiosperms. Development of insects and mammals, appearance of lemurs, later primates.
- Upper Tertiary period (Neogene). The formation of modern plants. The appearance of human ancestors.
- Quaternary period (Anthropocene). Formation of modern plants and animals. The appearance of man.

Development of inanimate conditions, climate change

The table of the development of life on Earth cannot be presented without data on changes in inanimate nature. The emergence and development of life on Earth, new species of plants and animals, all this is accompanied by changes in inanimate nature and climate.

Climate Change: Archean Era

The history of the development of life on Earth began through the stage of the predominance of land over water resources. The relief was poorly outlined. The atmosphere is dominated by carbon dioxide, the amount of oxygen is minimal. Shallow waters have low salinity.

The Archean era is characterized by volcanic eruptions, lightning, and black clouds. The rocks are rich in graphite.

Climatic changes in the Proterozoic era

The land is a rocky desert; all living organisms live in water. Oxygen accumulates in the atmosphere.

Climate Change: Paleozoic Era

During various periods of the Paleozoic era the following occurred:

Cambrian period. The land is still deserted. The climate is hot.
Ordovician period. The most significant changes are the flooding of almost all northern platforms.
Silurian. Tectonic changes and conditions of inanimate nature are varied. Mountain formation occurs and the seas dominate the land. Areas of different climates, including areas of cooling, have been identified.
Devonian. The climate is dry and continental. Formation of intermountain depressions.
Carboniferous period. Subsidence of continents, wetlands. The climate is warm and humid, with a lot of oxygen and carbon dioxide in the atmosphere.
Permian period. Hot climate, volcanic activity, mountain building, drying out of swamps.

During the Paleozoic era, mountains were formed. Such changes in relief affected the world's oceans - sea basins were reduced, and a significant land area was formed.

The Paleozoic era marked the beginning of almost all major oil and coal deposits.

Climatic changes in the Mesozoic

The climate of different periods of the Mesozoic is characterized by the following features:

Triassic. Volcanic activity, climate is sharply continental, warm.
Jurassic period. Mild and warm climate. The seas dominate the land.
Cretaceous period. Retreat of the seas from the land. The climate is warm, but at the end of the period global warming gives way to cooling.

In the Mesozoic era, previously formed mountain systems are destroyed, the plains go under water (Western Siberia). In the second half of the era, the Cordillera, the mountains of Eastern Siberia, Indochina, and partly Tibet were formed, and the mountains of Mesozoic folding were formed. The prevailing climate is hot and humid, promoting the formation of swamps and peat bogs.

Climate Change - Cenozoic Era

During the Cenozoic era, a general rise of the Earth's surface occurred. The climate has changed. Numerous glaciations of the earth's surfaces advancing from the north changed the appearance of the continents of the Northern Hemisphere. Thanks to such changes, the hilly plains were formed.

Lower Tertiary period. Mild climate. Division into 3 climatic zones. Formation of continents.
Upper Tertiary period. Dry climate. The emergence of steppes and savannas.
Quaternary period. Multiple glaciations of the northern hemisphere. Cooling climate.

All changes during the development of life on Earth can be written down in the form of a table that will reflect the most significant stages in the formation and development of the modern world. Despite the already known research methods, even now scientists continue to study history, making new discoveries that allow modern society to learn how life developed on Earth before the advent of man.

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

The gas and dust cloud transformed over time into the Solar System. And after the star appeared, the planets appeared. One of them was our native Earth. This 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.

Stages of Earth's development

The entire history of the Earth is divided into two huge stages.. 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 approximately 540 million years ago. This is the time when living multicellular organisms spread across 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 stages are called eons. Each eon has its own eonothema. The latter represents a certain stage of the geological development of the planet, which is radically 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 eons in total. Each of them, in turn, is divided into eras of the Earth, and those are divided into periods. From this it is clear that there is a strict gradation of large time intervals, and the geological development of the planet is taken as the basis.

Katarhey

The oldest eon is called Katarchean. 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 Katarchaean there was neither the earth's crust nor the core. The planet was a cold cosmic body. The temperature in its depths 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 or oxygen.

Archaea

The second eon is called Archean. 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, Paleoarchean, Mesoarchean and Neoarchean.

Eoarchaean(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. Comets could have brought it in large quantities. But the oceans were still far away. There were separate reservoirs, and the temperature in them reached 90° Celsius. The atmosphere was characterized by a high content of carbon dioxide and a low content of nitrogen. There was no oxygen. At the end of the era, the first supercontinent of Vaalbara began to form.

Paleoarchaean(3.6-3.2 billion years) lasted 400 million years. During this era, the formation of the solid core of the Earth was completed. A strong magnetic field appeared. His tension was half the current one. Consequently, the surface of the planet received protection from the solar wind. This period also saw primitive forms of life in the form of bacteria. Their remains, which are 3.46 billion years old, were discovered 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. The most remarkable thing about it was the existence of cyanobacteria. They are capable of photosynthesis and produce oxygen. The formation of the supercontinent has completed. By the end of the era it had split. There was also a huge asteroid impact. The crater from it still exists in Greenland.

Neoarchaean(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 develop. Traces of their life were 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 era, the Earth's era continued in the Proterozoic eon. This is a period of 2.5 billion years - 540 million years ago. It is the longest of all the eons on the planet.

Proterozoic

The Proterozoic is divided into 3 eras. The first one is called Paleoproterozoic(2.5-1.6 billion years). It lasted 900 million years. This huge time interval is divided into 4 periods: siderian (2.5-2.3 billion years), rhyasium (2.3-2.05 billion years), orosirium (2.05-1.8 billion years) , stateria (1.8-1.6 billion years).

Siderius notable in the first place oxygen catastrophe. It happened 2.4 billion years ago. Characterized by a dramatic change in the Earth's atmosphere. Free oxygen appeared in it in huge quantities. Before 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 proliferated on Earth 2.7 billion years ago. Before this, archaebacteria dominated. They did not produce oxygen during photosynthesis. In addition, oxygen was initially consumed in the oxidation of rocks. It accumulated in large quantities only in biocenoses or bacterial mats.

Eventually, a moment came when the surface of the planet became oxidized. And the cyanobacteria continued to release oxygen. And it began to accumulate in the atmosphere. The process 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 shrouded in the ozone layer and the greenhouse effect decreased. Accordingly, the boundaries of the biosphere expanded, and sedimentary and metamorphic rocks turned out to be completely oxidized.

All these metamorphoses led to Huronian glaciation, which lasted 300 million years. It began in Sideria, and ended at the end of Rhiasia 2 billion years ago. The next period of orosiria is notable for its intense 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 located in Canada. Its diameter is 250 km.

Last staterian period notable for the formation of the supercontinent Columbia. It includes 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. This was a very important stage of 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), exatium (1.4-1.2 billion years), sthenia (1.2-1 billion years).

During the time of Kalimium, the supercontinent Colombia broke up. And during the Exatian era, 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 Stenium. It arose 1.1 billion years ago and disintegrated 750 million years ago. Thus, by the end of the Mesoproterozoic there was 1 supercontinent and 1 ocean on Earth, called Mirovia.

The last era of the Proterozoic is called Neoproterozoic(1 billion-540 million years). It includes 3 periods: Thonian (1 billion-850 million years), Cryogenian (850-635 million years), Ediacaran (635-540 million years).

During the Thonian era, the supercontinent Rodinia began to disintegrate. This process ended in cryogeny, and the supercontinent Pannotia 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 it retreated, 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 began - the Phanerozoic. There are 3 very important eras of the Earth. The first one is called Paleozoic(540-252 million years). It lasted 288 million years. Divided into 6 periods: Cambrian (540-480 million years), Ordovician (485-443 million years), Silurian (443-419 million years), Devonian (419-350 million years), Carboniferous (359-299 million years) and Permian (299-252 million years).

Cambrian considered to be the lifespan of trilobites. These are marine animals similar to crustaceans. Along with them, jellyfish, sponges and worms lived in the seas. Such an 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. Naturally, they were not preserved. Therefore, complex multicellular organisms of more ancient eras cannot be detected.

The Paleozoic is notable for the rapid expansion of organisms with hard skeletons. From vertebrates, fish, reptiles and amphibians appeared. The plant world was initially dominated by algae. During Silurian plants began to colonize the land. At first Devonian The swampy shores are overgrown with primitive 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 colonize land during the Silurian period

Scorpions and spiders appeared. The dragonfly Meganeura was a real giant. Its wingspan reached 75 cm. Acanthodes are considered the oldest bony fish. They lived during the Silurian period. Their bodies were covered with dense diamond-shaped scales. IN carbon, which is also called the Carboniferous period, a wide variety of vegetation rapidly developed on the shores of 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 during 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 Eurasia and North America were formed. And from Gondwana arose South America, Africa, Australia and Antarctica.

On Permian there were frequent climate changes. Dry times alternated with wet ones. At this time, lush vegetation appeared on the banks. Typical plants were cordaites, calamites, tree and seed ferns. Mesosaur 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 firmly and densely settled on the blue planet.

The following eras of the Earth are of particular interest to scientists. 252 million years ago came Mesozoic. It lasted 186 million years and ended 66 million years ago. Consisted of 3 periods: Triassic (252-201 million years), Jurassic (201-145 million years), Cretaceous (145-66 million years).

The boundary between the Permian and Triassic periods is characterized by mass extinction of animals. 96% of marine species and 70% of terrestrial vertebrates died. The biosphere was dealt a very strong blow, 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 was the collapse of Pangea. A single supercontinent, as already mentioned, was divided into 2 continents, and then broke up into the continents that we know now. The Indian subcontinent also broke away. It subsequently connected with the Asian plate, but the collision was so violent that the Himalayas emerged.

This is what nature was like in the early Cretaceous period

The Mesozoic is notable for being considered the warmest period of the Phanerozoic eon.. This is the time of 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 across the planet. At the equator, the average annual temperature was 25-30° Celsius. The circumpolar 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 climate. It was at this time that the equatorial climate zone was formed.

In the animal world, mammals arose from the subclass of reptiles. This was due to the improvement of the nervous system and brain. The limbs moved from the sides under the body, and the reproductive organs became more advanced. They ensured the development of the embryo in the mother's body, followed by feeding it with milk. Hair 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 considered 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 million years), Neogene (23-2.6 million years) and the modern Anthropocene or Quaternary period, which began 2.6 million years ago.

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

Surface of the Earth 65 million years ago

After the fall, there was an explosion of enormous force. Dust rose into the atmosphere and blocked the planet from the sun's rays. The average temperature dropped by 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 became extinct. 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 terrestrial animals has increased significantly compared to the Paleozoic. They became much more advanced, and mammals took a dominant position on the planet. Higher angiosperms appeared in the plant world. This is the presence of a flower and an ovule. Cereal crops also appeared.

The most important thing in the last era is anthropogen or quaternary period, which began 2.6 million years ago. It consists of 2 eras: 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 species of animals that became extinct at the end of the era lived on Earth. 300 thousand years ago, man appeared on the blue planet. It is believed that the first Cro-Magnons chose the eastern regions of Africa. At the same time, Neanderthals lived on the Iberian Peninsula.

Notable for the Pleistocene and Ice Ages. For as long as 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. During cold times, glaciers advanced on the continents, and retreated during interglacial periods. At the same time, the level of the World Ocean rose. About 12 thousand years ago, already in the Holocene, the next ice age ended. The climate became warm and humid. Thanks to this, humanity spread throughout the planet.

The Holocene is an interglacial. It has been going on for 12 thousand years. Over the past 7 thousand years, human civilization has developed. The world has changed in many ways. Flora and fauna have undergone significant transformations thanks to human activity. Nowadays, many animal species are on the verge of extinction. Man has long considered himself the ruler of the world, but the era of the Earth has not gone away. Time continues its steady course, and the blue planet conscientiously revolves around the Sun. In a word, life goes on, but the future will show what will happen next.

The article was written by Vitaly Shipunov

Hello! In this article I want to tell you about the geochronological column. This is a column of periods of the Earth's development. And also in more detail about each era, thanks to which you can paint a picture of the formation of the Earth throughout its history. What types of life appeared first, how they changed, and how much it took.

The geological history of the Earth is divided into large intervals - eras, eras are divided into periods, periods are divided into epochs. This division was associated with events that took place on. Changes in the abiotic environment influenced the evolution of the organic world on Earth.

Geological eras of the Earth, or geochronological scale:

And now about everything in more detail:

Designations:
Eras;
Periods;
Epochs.

1. Catarchaean era (from the creation of the Earth, about 5 billion years ago, to the origin of life);

2. Archean era , the most ancient era (3.5 billion - 1.9 billion years ago);

3. Proterozoic era (1.9 billion – 570 million years ago);

The Archean and Proterozoic are still combined into the Precambrian. The Precambrian covers the largest portion of geological time. Areas of land and sea were formed, and active volcanic activity occurred. Shields of all continents were formed from Precambrian rocks. Traces of life are usually rare.

4. Palaeozoic (570 million - 225 million years ago) with such periods :

Cambrian period(from the Latin name for Wales)(570 million – 480 million years ago);

The transition to the Cambrian was marked by the unexpected appearance of a huge number of fossils. This is a sign of the beginning of the Paleozoic era. Marine flora and fauna flourished in numerous shallow seas. Trilobites were especially widespread.

Ordovician period(from the British Ordovician tribe)(480 million – 420 million years ago);

Much of the Earth was soft, and most of the surface was still covered by seas. The accumulation of sedimentary rocks continued, and mountain building occurred. There were reef-formers. There is an abundance of corals, sponges and mollusks.

Silurian (from the British Silure tribe)(420 million – 400 million years ago);

Dramatic events in the history of the Earth began with the development of jawless fish-like fish (the first vertebrates), which appeared in the Ordovician. Another significant event was the appearance of the first land animals in the Late Silurian.

Devonian (from Devonshire in England)(400 million – 320 million years ago);

In the Early Devonian, mountain-building movements reached their peak, but basically it was a period of spasmodic development. The first seed plants settled on land. A large variety and number of fish-like species were noted, and the first terrestrial animals developed. animals- amphibians.

Carboniferous or Carboniferous period (from the abundance of coal in the seams) (320 million – 270 million years ago);

Mountain building, folding, and erosion continued. In North America, swampy forests and river deltas were flooded, and large coal deposits were formed. The southern continents were covered by glaciation. Insects spread rapidly, and the first reptiles appeared.

Permian period (from the Russian city of Perm)(270 million - 225 million years ago);

On a large part of Pangea - the supercontinent that united everything - conditions prevailed. Reptiles spread widely and modern insects evolved. New terrestrial flora developed, including conifers. Several marine species have disappeared.

5. Mesozoic era (225 million - 70 million years ago) with such periods:

Triassic (from the tripartite division of the period proposed in Germany)(225 million – 185 million years ago);

With the onset of the Mesozoic era, Pangea began to disintegrate. On land, the dominance of conifers was established. Diversity among reptiles was noted, with the first dinosaurs and giant marine reptiles appearing. Primitive mammals evolved.

Jurassic period(from mountains in Europe)(185 million – 140 million years ago);

Significant volcanic activity was associated with the formation of the Atlantic Ocean. Dinosaurs dominated on land, flying reptiles and primitive birds conquered the air ocean. There are traces of the first flowering plants.

Cretaceous period (from the word "chalk")(140 million – 70 million years ago);

During the maximum expansion of the seas, chalk was deposited, especially in Britain. The dominance of dinosaurs continued until the extinction of them and other species at the end of the period.

6. Cenozoic era (70 million years ago - up to our time) with such periods And epochs:

Paleogene period (70 million – 25 million years ago);

— Paleocene epoch ("the oldest part of the new epoch")(70 million – 54 million years ago);
— Eocene Epoch ("dawn of a new era")(54 million – 38 million years ago);
— Oligocene Epoch ("not very new")(38 million – 25 million years ago);

Neogene period (25 million - 1 million years ago);

— Miocene Epoch ("relatively new")(25 million – 8 million years ago);
— Pliocene Epoch ("very recent")(8 million – 1 million years ago);

The Paleocene and Neogene periods are still combined into the Tertiary period. With the onset of the Cenozoic era (new life), mammals began to spread spasmodically. Many large species evolved, although many became extinct. The number of flowering plants has increased sharply plants. As the climate cooled, herbaceous plants appeared. There was a significant uplift of the land.

Quaternary period (1 million – our time);

— Pleistocene epoch (“most recent”)(1 million – 20 thousand years ago);

— Holocene era(“a completely new era”) (20 thousand years ago – our time).

This is the last geological period that includes the present time. Four major glaciations alternated with warming periods. The number of mammals has increased; they have adapted to . The formation of man - the future ruler of the Earth - took place.

There are also other ways of dividing eras, epochs, periods, eons are added to them, and some epochs are still divided, like on this table, for example.

But this table is more complex, the confusing dating of some eras is purely chronological, not based on stratigraphy. Stratigraphy is the science of determining the relative geological age of sedimentary rocks, the division of rock strata, and the correlation of various geological formations.

This division, of course, is relative, since there was no sharp distinction from today to tomorrow in these divisions.

But still, at the turn of neighboring eras and periods, significant geological transformations predominantly took place: processes of mountain formation, redistribution of seas, changing of the climate etc.

Each subsection was, of course, characterized by its unique flora and fauna.

, And You can read it in the same section.

Thus, these are the main eras of the Earth on which all scientists rely 🙂

Eras of life on Earth

The entire period of the existence of life on Earth can be divided into 2 periods: the Precambrian, or cryptozoic (primary period, 3.6 to 0.6 billion years), and the Phanerozoic.

The Cryptozoic includes the Archean (ancient life) and Proterozoic (primary life) eras.

The Phanerozoic includes the Paleozoic (ancient life), Mesozoic (middle life) and Cenozoic (new life) eras.

Eras of development, countdown

The most significant events are usually identified in special time intervals - eras. Time is counted down in reverse order, from ancient life to modern life. There are 5 eras:

Periods of development of life on Earth

The Paleozoic, Mesozoic and Cenozoic eras include periods of development. These are smaller periods of time compared to eras.

Cambrian (Cambrian).
Ordovician.
Silurian (Silurian).
Devonian (Devonian).
Carboniferous (carbon).
Perm (Perm).

Lower Tertiary (Paleogene).
Upper Tertiary (Neogene).
Quaternary, or Anthropocene (human development).

The first 2 periods are included in the Tertiary period lasting 59 million years.

Proterozoic era (early life)

6. Perm (Perm)

2. Upper Tertiary (Neogene)

3. Quaternary or Anthropocene (human development)

Development of living organisms

Archean era. The most significant changes in the evolution of living organisms are the appearance of blue-green algae - prokaryotes capable of reproduction and photosynthesis, and the emergence of multicellular organisms. The appearance of living protein substances (heterotrophs) capable of absorbing organic substances dissolved in water. Subsequently, the appearance of these living organisms made it possible to divide the world into plant and animal.

Mesozoic era.

Triassic. Distribution of plants (gymnosperms). Increase in the number of reptiles. The first mammals, bony fish.
Jurassic period. The predominance of gymnosperms, the emergence of angiosperms. The appearance of the first bird, the flourishing of cephalopods.
Cretaceous period. Distribution of angiosperms, decline of other plant species. Development of bony fishes, mammals and birds.

Cenozoic era.
- Lower Tertiary period (Paleogene). The rise of angiosperms. Development of insects and mammals, appearance of lemurs, later primates.
- Upper Tertiary period (Neogene). The formation of modern plants. The appearance of human ancestors.
- Quaternary period (Anthropocene). Formation of modern plants and animals. The appearance of man.

Development of inanimate conditions, climate change

Climate Change: Archean Era

The Archean era is characterized by volcanic eruptions, lightning, and black clouds. The rocks are rich in graphite.

Climatic changes in the Proterozoic era

The land is a rocky desert; all living organisms live in water. Oxygen accumulates in the atmosphere.

Climate Change: Paleozoic Era

The following climate changes occurred during various periods of the Paleozoic era:

Cambrian period. The land is still deserted. The climate is hot.
Ordovician period. The most significant changes are the flooding of almost all northern platforms.
Silurian. Tectonic changes and conditions of inanimate nature are varied. Mountain formation occurs and the seas dominate the land. Areas of different climates, including areas of cooling, have been identified.
Devonian. The climate is dry and continental. Formation of intermountain depressions.
Carboniferous period. Subsidence of continents, wetlands. The climate is warm and humid, with a lot of oxygen and carbon dioxide in the atmosphere.
Permian period. Hot climate, volcanic activity, mountain building, drying out of swamps.

During the Paleozoic era, the Caledonian fold mountains were formed. Such changes in relief affected the world's oceans - sea basins shrank and a significant land area formed.

The Paleozoic era marked the beginning of almost all major oil and coal deposits.

Climatic changes in the Mesozoic

The climate of different periods of the Mesozoic is characterized by the following features:

Triassic. Volcanic activity, climate is sharply continental, warm.
Jurassic period. Mild and warm climate. The seas dominate the land.
Cretaceous period. Retreat of the seas from the land. The climate is warm, but at the end of the period global warming gives way to cooling.

Climate Change - Cenozoic Era

Lower Tertiary period. Mild climate. Division into 3 climatic zones. Formation of continents.
Upper Tertiary period. Dry climate. The emergence of steppes and savannas.
Quaternary period. Multiple glaciations of the northern hemisphere. Cooling climate.

Development of life on Earth lasts more than 3 billion years. And this process continues to this day.

The first living things in the Archaean were bacteria. Then single-celled algae, animals and fungi appeared. Multicellular organisms replaced unicellular organisms. At the beginning of the Paleozoic, life was already very diverse: representatives of all types of invertebrates lived in the seas, and the first land plants appeared on land. In the following eras, over the course of many millions of years, different groups of plants and animals formed and died out. Gradually the living world became more and more similar to the modern one.

2.6. History of life development

Previously, scientists believed that living things came from living things. Bacterial spores were brought from space. Some bacteria created organic substances, others consumed and destroyed them. As a result, an ancient ecosystem arose, the components of which were connected by the cycle of substances.

Modern scientists have proven that living things came from inanimate nature. In the aquatic environment, organic substances were formed from inorganic substances under the influence of the energy of the Sun and the internal energy of the Earth. The most ancient organisms - bacteria - were formed from them.

In the history of the development of life on Earth, several eras are distinguished.

Archaea

The first organisms were prokaryotes. In the Archean era, a biosphere already existed, consisting mainly of prokaryotes. The very first living creatures on the planet are bacteria. Some of them were capable of photosynthesis. Photosynthesis was carried out by cyanobacteria (blue-green).

Proterozoic

As oxygen levels increased in the atmosphere, eukaryotic organisms began to appear. In the Proterozoic, unicellular plants, and then unicellular animals and fungi, arose in the aquatic environment. An important event of the Proterozoic was the emergence of multicellular organisms. By the end of the Proterozoic, various types of invertebrates and chordates had already appeared.

Paleozoic

Plants

Gradually, dry land arose in place of the warm, shallow seas. As a result, the first land plants evolved from multicellular green algae. In the second half of the Paleozoic, forests appeared. They consisted of ancient ferns, horsetails and mosses, which reproduced by spores.

Animals

At the beginning of the Paleozoic, marine invertebrates flourished. Vertebrate animals - armored fish - developed and spread in the seas.

In the Paleozoic, the first terrestrial vertebrates appeared - the oldest amphibians. From them at the end of the era the first reptiles originated.

The most numerous in the seas of the Paleozoic (era of ancient life) were trilobites - fossil arthropods that looked like giant woodlice. Trilobites - existed at the beginning of the Paleozoic, completely died out 200 million years ago. They swam and crawled in shallow bays, feeding on plants and animal remains. There is an assumption that there were predators among the trilobites.

The very first animals to colonize land were arachnids and giant flying insects - the ancestors of modern dragonflies. Their wingspan reached 1.5 m.

Mesozoic

During the Mesozoic, the climate became drier. The ancient forests gradually disappeared. Spore-bearing plants were replaced by plants that reproduce by seeds. Among animals, reptiles, including dinosaurs, flourished. At the end of the Mesozoic, many species of ancient seed plants and dinosaurs became extinct.

Animals

The largest of the dinosaurs were brachiosaurs. They reached more than 30 m in length and weighed 50 tons. These dinosaurs had a huge body, long tail and neck, and a small head. If they lived in our time, they would be taller than five-story buildings.

Plants

The most complexly organized plants are flowering plants. They appeared in the middle of the Mesozoic (the era of middle life). Material from the site http://wikiwhat.ru

Cenozoic

The Cenozoic is the heyday of birds, mammals, insects and flowering plants. In birds and mammals, due to the more advanced structure of organ systems, warm-bloodedness arose. They became less dependent on environmental conditions and spread widely on Earth.

Geological chronology, or geochronology, is based on elucidating the geological history of the best-studied regions, such as Central and Eastern Europe. Based on broad generalizations, comparison of the geological history of various regions of the Earth, patterns of evolution of the organic world, at the end of the last century, at the first International Geological Congresses, the International Geochronological Scale was developed and adopted, reflecting the sequence of divisions of time during which certain complexes of sediments were formed, and the evolution of the organic world . Thus, the international geochronological scale is a natural periodization of the history of the Earth.

Among the geochronological divisions there are: eon, era, period, epoch, century, time. Each geochronological division corresponds to a complex of sediments, identified in accordance with changes in the organic world and called stratigraphic: eonothem, group, system, department, stage, zone. Therefore, a group is a stratigraphic unit, and the corresponding time geochronological unit is an era. Therefore, there are two scales: geochronological and stratigraphic. The first is used when talking about relative time in the history of the Earth, and the second when dealing with sediments, since some geological events occurred in every place on the globe at any time. Another thing is that the accumulation of precipitation was not widespread.

The Archean and Proterozoic eonothems, covering almost 80% of the Earth's existence, are classified as cryptozoic, since Precambrian formations completely lack skeletal fauna and the paleontological method is not applicable to their dissection. Therefore, the division of Precambrian formations is based primarily on general geological and radiometric data.
The Phanerozoic eon covers only 570 million years and the division of the corresponding eonothem of sediments is based on a wide variety of numerous skeletal fauna. The Phanerozoic eonothem is divided into three groups: Paleozoic, Mesozoic and Cenozoic, corresponding to major stages of the natural geological history of the Earth, the boundaries of which are marked by rather sharp changes in the organic world.

The names of eonotemes and groups come from Greek words:

"archeos" - the most ancient, the most ancient;
"proteros" - primary;
"paleos" - ancient;
"mesos" - average;
"kainos" - new.

The word "cryptos" means hidden, and "phanerozoic" means obvious, transparent, since the skeletal fauna appeared.
The word "zoy" comes from "zoikos" - life. Therefore, the “Cenozoic era” means the era of new life, etc.

Groups are divided into systems, the deposits of which were formed during one period and are characterized only by their own families or genera of organisms, and if these are plants, then by genera and species. Systems have been identified in different regions and at different times since 1822. Currently, 12 systems are recognized, most of whose names come from the places where they were first described. For example, the Jurassic system - from the Jurassic Mountains in Switzerland, the Permian - from the Perm province in Russia, the Cretaceous - from the most characteristic rocks - white writing chalk, etc. The Quaternary system is often called the anthropogenic system, since it is in this age interval that humans appear.

Systems are divided into two or three divisions, which correspond to the early, middle, and late eras. The departments, in turn, are divided into tiers, which are characterized by the presence of certain genera and types of fossil fauna. And finally, the stages are divided into zones, which are the most fractional part of the international stratigraphic scale, to which time corresponds on the geochronological scale. The names of the tiers are usually given by the geographical names of the areas where this tier was identified; for example, Aldanian, Bashkir, Maastrichtian stages, etc. At the same time, the zone is designated by the most characteristic type of fossil fauna. The zone, as a rule, covers only a certain part of the region and is developed over a smaller area than the deposits of the stage.

All divisions of the stratigraphic scale correspond to the geological sections in which these divisions were first identified. Therefore, such sections are standard, typical and are called stratotypes, which contain only their own complex of organic remains, which determines the stratigraphic volume of a given stratotype. Determining the relative age of any layers consists of comparing the discovered complex of organic remains in the studied layers with the complex of fossils in the stratotype of the corresponding division of the international geochronological scale, i.e. the age of sediments is determined relative to the stratotype. That is why the paleontological method, despite its inherent shortcomings, remains the most important method for determining the geological age of rocks. Determining the relative age of, for example, Devonian deposits only indicates that these deposits are younger than the Silurian, but older than the Carboniferous. However, it is impossible to establish the duration of the formation of Devonian deposits and give a conclusion about when (in absolute chronology) the accumulation of these deposits occurred. Only methods of absolute geochronology can answer this question.

Tab. 1. Geochronological table

Era	Period	era	Duration, million years	Time from the beginning of the period to the present day, million years	Geological conditions	Vegetable world	Animal world
Cenozoic (time of mammals)	Quaternary	Modern	0,011	0,011	The end of the last ice age. The climate is warm	Decline of woody forms, flourishing of herbaceous forms	Age of Man
	Quaternary	Pleistocene	1	1	Repeated glaciations. Four Ice Ages	Extinction of many plant species	Extinction of large mammals. The Birth of Human Society
	Tertiary	Pliocene	12	13	Mountains continue to rise in western North America. Volcanic activity	Forest decline. Distribution of grasslands. Flowering plants; development of monocots	The emergence of man from apes. Species of elephants, horses, camels, similar to modern ones
		Miocene	13	25	The Sierras and Cascade Mountains were formed. Volcanic activity in the northwestern United States. The climate is cool		The culminating period in the evolution of mammals. The first great apes
		Oligocene	11	30	The continents are low. The climate is warm	Maximum distribution of forests. Enhancing the development of monocot flowering plants	Archaic mammals are dying out. The beginning of the development of anthropoids; ancestors of most living mammal genera
		Eocene	22	58	The mountains are washed away. There are no inland seas. The climate is warm		Diverse and specialized placental mammals. Ungulates and predators reach their peak
		Paleocene	5	63			Distribution of archaic mammals
Alpine orogeny (minor fossil destruction)
Mesozoic (time of reptiles)	Chalk		72	135	At the end of the period, the Andes, Alps, Himalayas, and Rocky Mountains are formed. Before this, inland seas and swamps. Deposition of writing chalk, clay shales	The first monocots. The first oak and maple forests. Decline of gymnosperms	Dinosaurs reach their highest development and die out. Toothed birds are becoming extinct. The appearance of the first modern birds. Archaic mammals are common
	Yura		46	181	The continents are quite elevated. Shallow seas cover parts of Europe and the western United States	The importance of dicotyledons is increasing. Cycadophytes and conifers are common	The first toothed birds. Dinosaurs are large and specialized. Insectivorous marsupials
	Triassic		49	230	Continents are elevated above sea level. Intensive development of arid climate conditions. Widespread continental sediments	The dominance of gymnosperms, already beginning to decline. Extinction of seed ferns	The first dinosaurs, pterosaurs and egg-laying mammals. Extinction of primitive amphibians
Hercynian orogeny (some fossil destruction)
Paleozoic (era of ancient life)	Permian		50	280	The continents are uplifted. The Appalachian Mountains were formed. Dryness is increasing. Glaciation in the Southern Hemisphere	Decline of club mosses and ferns	Many ancient animals are becoming extinct. Animal-like reptiles and insects develop
	Upper and mid carbon		40	320	Continents are low-lying at first. Vast swamps where coal formed	Large forests of seed ferns and gymnosperms	The first reptiles. Insects are common. Distribution of ancient amphibians
	Lower Carboniferous		25	345	The climate is initially warm and humid, later, due to the rise of land, it becomes cooler	Moss mosses and fern-like plants dominate. Gymnosperms are becoming more widespread	Sea lilies reach their highest development. Distribution of ancient sharks
	Devonian		60	405	Inland seas are small. Raising land; development of an arid climate. Glaciation	The first forests. Land plants are well developed. First gymnosperms	The first amphibians. Abundance of lungfish and sharks
	Silur		20	425	Vast inland seas. Low-lying areas become increasingly arid as land rises	The first reliable traces of land plants. Algae dominates	Marine arachnids dominate. The first (wingless) insects. Fish development is enhanced
	Ordovician		75	500	Significant immersion of land. The climate is warm, even in the Arctic	The first land plants probably appear. Abundance of seaweed	The first fish were probably freshwater. Abundance of corals and trilobites. Various shellfish
	Cambrian		100	600	The continents are low-lying and the climate is temperate. The most ancient rocks with abundant fossils	Seaweed	Trilobites and non-cured ones dominate. Origins of most modern animal types
Second great orogeny (significant destruction of fossils)
Proterozoic			1000	1600	Intensive process of sedimentation. Later - volcanic activity. Erosion over large areas. Multiple glaciations	Primitive aquatic plants - algae, mushrooms	Various marine protozoa. By the end of the era - molluscs, worms and other marine invertebrates
First great orogeny (significant destruction of fossils)
Archaea			2000	3600	Significant volcanic activity. Weak sedimentation process. Erosion on large areas	There are no fossils. Indirect indications of the existence of living organisms in the form of deposits of organic matter in rocks

The problem of determining the absolute age of rocks and the duration of the Earth's existence has long occupied the minds of geologists, and attempts to solve it have been made many times, using various phenomena and processes. Early ideas about the absolute age of the Earth were curious. A contemporary of M.V. Lomonosov, the French naturalist Buffon, determined the age of our planet at only 74,800 years. Other scientists gave different figures, not exceeding 400-500 million years. It should be noted here that all these attempts were doomed to failure in advance, since they were based on the constancy of the rates of processes that, as is known, changed in the geological history of the Earth. And only in the first half of the 20th century. there was a real opportunity to measure the truly absolute age of rocks, geological processes and the Earth as a planet.

Table 2. Isotopes used to determine absolute age
Parent isotope	Final product	Half-life, billion years
147 Sm	143Nd+He	106
238 U	206 Pb+ 8 He	4,46
235 U	208 Pb+ 7 He	0,70
232 Th	208 Pb+ 6 He	14,00
87 Rb	87 Sr+β	48,80
40K	40 Ar+ 40 Ca	1,30
14 C	14N	5730 years