Geological era in the development of the earth. How are the periods of the geological history of the earth named in chronological order

According to modern concepts, it has an age of 4.5 - 5 billion years. In the history of its occurrence, planetary and geological stages are distinguished.

Geological stage- the sequence of events in the development of the Earth as planets since the formation of the earth's crust. In the course of it, relief forms arose and collapsed, the land was submerged under water (the advance of the sea), the retreat of the sea, glaciation, the appearance and disappearance of various species of animals and plants, etc.

Scientists, trying to restore the history of the planet, study the layers of rocks. They divide all deposits into 5 groups, distinguishing the following eras: Archean (ancient), Proterozoic (early), Paleozoic (ancient), Mesozoic (middle) and Cenozoic (new). The boundary between eras runs along the largest evolutionary events. The last three eras are divided into periods, since in these deposits the remains of animals and plant remains are better preserved and in greater numbers.

Each era is characterized by events that had a decisive influence on modern relief.

Archean era was distinguished by violent volcanic activity, as a result of which igneous granite-containing rocks appeared on the surface of the Earth - the basis of future continents. At that time, the Earth was inhabited only by microorganisms that could live without oxygen. It is believed that the deposits of that era cover certain areas of land with an almost continuous shield, they contain a lot of iron, gold, silver, platinum and ores of other metals.

AT Proterozoic era Volcanic activity was also high, and mountains of the so-called Baikal folding formed. They have practically not been preserved and now represent only separate small uplifts on the plains. During this period, the planet was inhabited by blue-green algae and protozoa, and the first multicellular organisms arose. Proterozoic rock layers are rich in minerals: iron ores and non-ferrous metal ores, mica.

At the beginning Paleozoic era formed the mountains Caledonian folding, which led to a reduction in sea basins and the emergence of significant land areas. In the form of mountains, only individual ranges of the Urals, Arabia, Southeast China and Central Europe have been preserved. All these mountains are low, "worn out". In the second half of the Paleozoic, mountains of Hercynian folding formed. This era of mountain building was more powerful, vast mountain ranges arose on the territory of Western Siberia and the Urals, Mongolia and Manchuria, most of Central Europe, the eastern coast of North America and Australia. Now they are represented by low blocky mountains. In the Paleozoic era, the Earth is inhabited by fish, amphibians and reptiles, algae predominate among the vegetation. The main deposits of oil and coal appeared during this period.

Mesozoic era began with a period of relative calm of the internal forces of the Earth, the gradual destruction of previously created mountain systems and the submersion of flattened flat territories, for example, most of Western Siberia, under water. In the second half of the era, mountains of Mesozoic folding formed. At this time, vast mountainous countries appeared, which even now have the appearance of mountains. These are the Cordilleras, the mountains of Eastern Siberia, certain parts of Tibet and Indochina. The land was covered with lush vegetation, which gradually died off and rotted. In a hot and humid climate, swamps and peat bogs were actively formed. It was the age of the dinosaurs. Giant predatory and herbivorous animals have spread almost all over the planet. At this time, the first mammals appeared.

Cenozoic era continues to this day. Its beginning was marked by an increase in the activity of the internal forces of the Earth, which led to a general uplift of the surface. In the era of Alpine folding, young folded mountains arose within the Alpine-Himalayan belt and the continent of Eurasia acquired its modern outlines. In addition, there was a rejuvenation of the ancient mountain ranges of the Urals, Appalachians, Tien Shan, Altai. The climate on the planet has changed dramatically, a period of powerful glaciation has begun. Ice sheets advancing from the north have changed the relief of the continents of the Northern Hemisphere, forming hilly plains with a large number of lakes.

The entire geological history of the Earth can be traced on a geochronological scale - a table of geological time, showing the sequence and subordination of the main stages of geology, the history of the Earth and the development of life on it (see Table 4 on pp. 46-49). The geochronological table should be read from bottom to top.

Questions and tasks for preparing for the exam

1. Explain why polar days and nights are observed on Earth.
2. What would be the conditions on the Earth if the axis of its rotation was not inclined to the plane of the orbit?
3. The change of seasons on Earth is determined by two main reasons: the first is the revolution of the Earth around the Sun; name the second one.
4. How many times a year and when is the Sun at its zenith above the equator? Over the Tropic of the North? Over the Southern Tropic?
5. In what direction do constant winds and sea currents moving in the meridional direction deviate in the Northern Hemisphere?
6. When is the shortest night in the Northern Hemisphere?
7. What characterizes the days of the spring and autumn equinoxes on Earth? When do they advance in the Northern and Southern Hemispheres?
8. When are the summer and winter solstices in the Northern and Southern Hemispheres?
9. In what zones of illumination is the territory of our country located?
10. List the geological periods of the Cenozoic era, starting with the most ancient.

Table 4

Geological scale

Eras (duration - in million years)	Periods (duration in million years)	The most important events in the history of the Earth	Characteristic minerals formed at a given time
1	2	3	4
Cenozoic 70 Ma	Quaternary 2 Ma (Q)	General land uplift. Repeated ice sheets, especially in the Northern Hemisphere. The appearance of man	Peat, alluvial deposits of gold, diamonds, dredges, stones
	Neogene 25 Ma (N)	The emergence of young mountains in areas of alpine folding. Rejuvenation of mountains in the regions of all ancient foldings. dominance of flowering plants	Brown coals, oil, amber
	Paleogene 41 Ma (P)	Destruction of mountains of Mesozoic folding. Wide development of flowering plants, birds and mammals	Phosphorites, brown coals, bauxites

Mesozoic 165 Ma	Cretaceous 70 Ma (K)	The emergence of young mountains in the areas of Mesozoic folding. Extinction of giant reptiles (dinosaurs). Development of birds and mammals	Oil, oil shale, chalk, coal, phosphorites
	Jurassic 50 Ma (J)	Formation of modern oceans. Hot and humid climate over most of the land. The rise of giant reptiles (dinosaurs). dominance of gymnosperms	Coals, oil, phosphorites
	Triassic 40 Ma (T)	The greatest retreat of the sea and the rise of land in the history of the Earth. Destruction of the mountains of the Caledonian and Hercynian foldings. Vast deserts. First mammals	rock salts
1	2	3	4
Paleozoic 330 Ma	Permian 45 Ma (P)	The emergence of young folded mountains in areas of Hercynian folding. Dry climate over most of the land. The emergence of gymnosperms	Rock and potash salts, gypsum
	Carboniferous 65 Ma (C)	Hot and humid climate over most of the land. Widespread swampy lowlands in coastal areas. Forests of tree ferns. The first reptiles, the heyday of amphibians	Coal, oil
	Devonian 55 Ma (p)	Hot climate over most of the land. First deserts. The appearance of amphibians. Numerous fish	Salt, oil
	Silurian 35 Ma (S)	The emergence of young folded mountains in the areas of the Caledonian folding. The first land plants (mosses and ferns)

	Ordovician 60 Ma (O)	Decrease in the area of marine basins. The appearance of the first terrestrial invertebrates
	Cambrian 70 Ma	The emergence of young mountains in the areas of Baikal folding. Flooding of vast areas by the seas. The rise of marine invertebrates	Rock salt, gypsum, phosphate rock
Proterozoic era 600 Ma		Beginning of the Baikal folding. Powerful volcanism. Development of bacteria and blue-green algae	Iron ores, mica, graphite
Archean era 900 Ma		Formation of the continental crust. Intense volcanic activity. Time of primitive unicellular bacteria	ores

Maksakovskiy V.P., Petrova N.N., Physical and economic geography of the world. - M.: Iris-press, 2010. - 368 pp.: ill.

Lesson content lesson summary support frame lesson presentation accelerative methods interactive technologies Practice tasks and exercises self-examination workshops, trainings, cases, quests homework discussion questions rhetorical questions from students Illustrations audio, video clips and multimedia photographs, pictures graphics, tables, schemes humor, anecdotes, jokes, comics parables, sayings, crossword puzzles, quotes Add-ons abstracts articles chips for inquisitive cheat sheets textbooks basic and additional glossary of terms other Improving textbooks and lessonscorrecting errors in the textbook updating a fragment in the textbook elements of innovation in the lesson replacing obsolete knowledge with new ones Only for teachers perfect lessons calendar plan for the year methodological recommendations of the discussion program Integrated Lessons

Geological time and methods for its determination

In the study of the Earth as a unique cosmic object, the idea of its evolution occupies a central place, therefore an important quantitative evolutionary parameter is geological time. The study of this time is engaged in a special science called Geochronology- geological reckoning. Geochronology may be absolute and relative.

Remark 1

Absolute geochronology deals with the determination of the absolute age of rocks, which is expressed in units of time and, as a rule, in millions of years.

The determination of this age is based on the rate of decay of isotopes of radioactive elements. This speed is a constant value and does not depend on the intensity of physical and chemical processes. Age determination is based on nuclear physics methods. Minerals containing radioactive elements, during the formation of crystal lattices, form a closed system. In this system, the accumulation of radioactive decay products occurs. As a result, the age of the mineral can be determined if the rate of this process is known. The half-life of radium, for example, is $1590$ years, and the complete decay of the element will occur in $10$ times the half-life. Nuclear geochronology has its leading methods − lead, potassium-argon, rubidium-strontium and radiocarbon.

Methods of nuclear geochronology made it possible to determine the age of the planet, as well as the duration of eras and periods. Radiological time measurement proposed P. Curie and E. Rutherford at the beginning of the $XX$ century.

Relative geochronology operates with such concepts as "early age, middle, late". There are several developed methods for determining the relative age of rocks. They fall into two groups - paleontological and non-paleontological.

First play a major role due to their versatility and ubiquity. The exception is the absence of organic remains in the rocks. With the help of paleontological methods, the remains of ancient extinct organisms are studied. Each rock layer has its own complex of organic remains. In each young layer there will be more remains of highly organized plants and animals. The higher the layer lies, the younger it is. A similar pattern was established by the Englishman W. Smith. He owns the first geological map of England, on which the rocks were divided by age.

Non-paleontological methods determinations of the relative age of rocks are used in cases where there are no organic remains in them. More efficient then will be stratigraphic, lithological, tectonic, geophysical methods. Using the stratigraphic method, it is possible to determine the sequence of stratification of layers in their normal occurrence, i.e. the underlying layers will be older.

Remark 3

The sequence of formation of rocks determines relative geochronology, and their age in units of time determines already absolute geochronology. Task geological time is to determine the chronological sequence of geological events.

Geological table

To determine the age of rocks and their study, scientists use various methods, and for this purpose a special scale has been compiled. Geological time on this scale is divided into time periods, each of which corresponds to a certain stage in the formation of the earth's crust and the development of living organisms. The scale is called geochronological table, which includes the following divisions: eon, era, period, epoch, century, time. Each geochronological unit is characterized by its own set of deposits, which is called stratigraphic: eonoteme, group, system, department, tier, zone. A group, for example, is a stratigraphic unit, and the corresponding temporal geochronological unit is era. Based on this, there are two scales - stratigraphic and geochronological. The first scale is used when it comes to deposits, because in any period of time some geological events took place on the Earth. The second scale is needed to determine relative time. Since the adoption of the scale, the content of the scale has been changed and refined.

The largest stratigraphic units at present are eonotemes - Archean, Proterozoic, Phanerozoic. In the geochronological scale, they correspond to zones of different duration. According to the time of existence on Earth, they are distinguished Archean and Proterozoic eonotemes covering nearly $80$% of the time. Phanerozoic eon in time is much less than the previous eon and covers only $ 570 $ million years. This ionoteme is divided into three main groups - Paleozoic, Mesozoic, Cenozoic.

The names of eonotems and groups are of Greek origin:

Archeos means ancient;
Proteros - primary;
Paleos - ancient;
Mezos - medium;
Cainos is new.

From the word " zoiko s”, which means vital, the word “ zoi". Based on this, the eras of life on the planet are distinguished, for example, the Mesozoic era means the era of average life.

Eras and periods

According to the geochronological table, the history of the Earth is divided into five geological eras: Archean, Proterozoic, Paleozoic, Mesozoic, Cenozoic. The eras are further subdivided into periods. There are much more of them - $12$. The duration of the periods varies from $20$-$100$ million years. The last one points to its incompleteness. Quaternary period of the Cenozoic era, its duration is only $1.8 million years.

Archean era. This time began after the formation of the earth's crust on the planet. By this time there were mountains on the Earth and the processes of erosion and sedimentation had come into play. The Archean lasted for approximately $2 billion years. This era is the longest in duration, during which volcanic activity was widespread on Earth, there were deep uplifts, which resulted in the formation of mountains. Most of the fossils were destroyed under the influence of high temperature, pressure, mass movement, but little data about that time was preserved. In the rocks of the Archean era, pure carbon is found in dispersed form. Scientists believe that these are altered remains of animals and plants. If the amount of graphite reflects the amount of living matter, then there was a lot of it in the Archaean.

Proterozoic era. In terms of duration, this is the second era, spanning $1 billion years. During the era, there was the deposition of a large amount of precipitation and one significant glaciation. Ice sheets extended from the equator to $20$ degrees of latitude. Fossils found in the rocks of this time are evidence of the existence of life and its evolutionary development. Spicules of sponges, remains of jellyfish, fungi, algae, arthropods, etc. have been found in the Proterozoic deposits.

Palaeozoic. This era stands out six periods:

Cambrian;
Ordovician,
Silur;
Devonian;
Carbon or coal;
Perm or Perm.

The duration of the Paleozoic is $370$ million years. During this time, representatives of all types and classes of animals appeared. Only birds and mammals were missing.

Mesozoic era. The era is divided into three period:

Triassic;

The era started about $230 million years ago and lasted $167 million years. During the first two periods Triassic and Jurassic- most of the continental regions rose above sea level. The climate of the Triassic is dry and warm, and in the Jurassic it became even warmer, but was already humid. In state Arizona there is a famous stone forest that has existed since Triassic period. True, only trunks, logs and stumps remained from the once mighty trees. At the end of the Mesozoic era, or rather in the Cretaceous period, a gradual advance of the sea takes place on the continents. The North American continent experienced a subsidence at the end of the Cretaceous and, as a result, the waters of the Gulf of Mexico joined with the waters of the Arctic basin. The mainland was divided into two parts. The end of the Cretaceous period is characterized by a large uplift, called Alpine orogeny. At this time, the Rocky Mountains, the Alps, the Himalayas, the Andes appeared. In the west of North America, intense volcanic activity began.

Cenozoic era. This is a new era that has not yet ended and continues at the present time.

The era was divided into three periods:

Paleogene;
Neogene;
Quaternary.

Quaternary period has a number of unique features. This is the time of the final formation of the modern face of the Earth and ice ages. New Guinea and Australia became independent, moving closer to Asia. Antarctica has remained in its place. Two Americas united. Of the three periods of the era, the most interesting is quaternary period or anthropogenic. It continues today, and was allocated in $1829$ by a Belgian geologist J. Denoyer. Coolings are replaced by warmings, but its most important feature is appearance of man.

Modern man lives in the Quaternary period of the Cenozoic era.

At first there was nothing. In the vast outer space, there was only a giant cloud of dust and gases. It can be assumed that from time to time spaceships with representatives of the universal mind rushed through this substance at great speed. 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 the solar system. And after the luminary appeared, the planets appeared. One of them was our native Earth. 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.

Stages of the Earth's development

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 divided into eras 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, Paleoarchean, Mesoarchean and 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 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 Vaalbar 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 are 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), riasium (2.3-2.05 billion years), orosirium (2.05-1.8 billion years) , statery (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. It contained a large amount of free oxygen. 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. In 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 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 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. This was a very important stage in 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), stenium (1.2-1 billion years).

At the time of the kalimium, the supercontinent Columbia collapsed. 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: Tonian (1 billion-850 million years), Cryogeny (850-635 million years), Ediacaran (635-540 million years).

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 million years). It lasted 288 million years. It is 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 Ma) and 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. In the plant world, algae predominated at first. 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. Acanthodes are considered the oldest bony fish. 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 Eurasia and North America were formed. And South America, Africa, Australia and Antarctica arose from Gondwana.

On the Permian there were frequent climate changes. 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. 252 million years ago mesozoic. It lasted 186 million years and ended 66 million years ago. It consisted of 3 periods: Triassic (252-201 million years), Jurassic (201-145 million years), Cretaceous (145-66 million years).

The border between the Permian and the Triassic period is characterized by the mass extinction of animals. 96% of marine species and 70% of terrestrial vertebrates died. A very strong blow was dealt to the biosphere, 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 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 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. This was due to the improvement of the nervous system and 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: the Paleogene (66-23 million years), the Neogene (23-2.6 million years) and 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. The diameter of the 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 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 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.

The article was written by Vitaly Shipunov

Hey! 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 more about each era, thanks to which you can draw a picture of the formation of the Earth throughout its history. What types of life first appeared, how did they change, and how much did it take.

The geological history of the Earth is divided into large intervals - eras, eras are divided into periods, periods are divided into epochs. Such a division was associated with events that took place on. The change 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. Catharchean 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);

Archean and Proterozoic are still combined into Precambrian. The Precambrian covers the largest part of geological time. Formed, areas of land and sea, active volcanic activity took place. 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 is marked by the unexpected appearance of a huge number of fossils. This is a sign of the beginning of the Paleozoic era. Marine life flourished in numerous shallow seas. Trilobites were especially widespread.

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

On a significant part of the Earth it was soft, most of the surface was still covered by the sea. The accumulation of sedimentary rocks continued, mountain building took place. There were reef builders. An abundance of corals, sponges and molluscs has been noted.

Silurian (from the British Silur tribe)(420 million - 400 million years ago);

Dramatic events in the history of the Earth began with the development of jawless fish (the first vertebrates), which appeared in the Ordovician. Another significant event was the appearance in the late Silurian of the first terrestrial.

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 great variety and number of fish-like species was noted, the first terrestrial 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 carbonaceous deposits formed. The southern continents were covered by glaciation. Insects spread rapidly, the first reptiles appeared.

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

A large part of Pangea - the supercontinent that united everything - was dominated by conditions. Reptiles spread widely, modern insects evolved. A 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 advent of the Mesozoic era, Pangea began to disintegrate. On land, the dominance of conifers was established. Diversity among reptiles is noted, the first dinosaurs and giant marine reptiles appeared. 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 the 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 deposits occurred, 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 era ("not very new")(38 million - 25 million years ago);

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

— Miocene epoch ("comparatively new")(25 million - 8 million years ago);
— Pliocene epoch ("very new")(8 million - 1 million years ago);

The Paleocene and Neocene periods are still combined into the Tertiary period. With the advent of the Cenozoic era (new life), there is an abrupt spread of mammals. Many large species have evolved, although many have become extinct. There has been a sharp increase in the number of flowering plants. With the cooling of the climate, herbaceous plants appeared. There has been a significant uplift.

Quaternary period (1 million - our time);

— Pleistocene era ("newest")(1 million - 20 thousand years ago);

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

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

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

But this table is more complicated, the confusing dating of some eras is purely chronological, not based on stratigraphy. Stratigraphy is the science of determining the relative geologic age of sedimentary rocks, subdividing rock strata, and correlating different geological formations.

Such a division, of course, is relative, since there was no sharp distinction between today and tomorrow in these divisions.

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

Each subsection was characterized, of course, by the originality of flora and fauna.

, and can be found in the same section.

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

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Hosted at http://www.allbest.ru/

abstract

Geological table of the Earth

Completed by: Mikhail Konyshev

Introduction

Geological scale- the geological time scale of the history of the Earth, used in geology and paleontology, a kind of calendar for time intervals of hundreds of thousands and millions of years.

According to modern generally accepted ideas, the age of the Earth is estimated at 4.5-4.6 billion years. No rocks or minerals have been found on the surface of the Earth that could be witnesses to the formation of the planet. The maximum age of the Earth is limited by the age of the earliest solid formations in the solar system - refractory inclusions rich in calcium and aluminum (CAI) from carbonaceous chondrites. The age of the CAI from the Allende meteorite according to the results of modern studies of the U-Pb isotope method is 4568.5±0.5 Ma. This is the best estimate of the age of the solar system to date. The time of the formation of the Earth as a planet may be later than this date by millions and even many tens of millions of years.

Subsequent time in the history of the Earth was divided into different time intervals according to the most important events that took place then.

The boundary between the Phanerozoic eras runs along the largest evolutionary events - global extinctions. The Paleozoic is separated from the Mesozoic by the largest Permian-Triassic extinction of species in the history of the Earth. The Mesozoic was separated from the Cenozoic by the Cretaceous-Paleogene extinction.

The history of the scale

In the second half of the 19th century, at the II-VIII sessions of the International Geological Congress (IGC) in 1881-1900. the hierarchy and nomenclature of most modern geochronological units were adopted. Subsequently, the International geochronological (stratigraphic) scale was constantly refined.

The specific names of the periods were given according to various criteria. The most commonly used place names. So, the name of the Cambrian period comes from lat. Cambria - the name of Wales when it was part of the Roman Empire, Devonian - from the county of Devonshire in England, Permian - from the city of Perm, Jurassic - from the Yuram Mountains in Europe. In honor of the ancient tribes, the Vendian (Vmends - the German name for the Slavic people of the Lusatian Sorbs), Ordovician and Silurian (tribes of the Celts Ordomviks and Silumrs) periods are named. Names associated with the composition of the rocks were used less frequently. The Carboniferous period is named because of the large number of coal seams, and the Cretaceous period because of the widespread use of writing chalk.

The principle of constructing the scale

geochronological scale earth geology

The geochronological scale was created to determine the relative geological age of rocks. Absolute age, measured in years, is of secondary importance to geologists.

The time of the existence of the Earth is divided into two main intervals (eons): Phanerozoic and Precambrian (Cryptozoic) according to the appearance of fossil remains in sedimentary rocks. Cryptozoic is a time of hidden life, in which only soft-bodied organisms existed, leaving no traces in sedimentary rocks. The Phanerozoic began with the appearance of many species of mollusks and other organisms on the border of the Ediacaran (Vendian) and Cambrian, allowing paleontology to dissect the strata according to the finds of fossil flora and fauna.

Another major division of the geochronological scale has its origin in the very first attempts to divide the history of the earth into major time intervals. Then the whole history was divided into four periods: the primary, which is equivalent to the Precambrian, the secondary - the Paleozoic and Mesozoic, the tertiary - the entire Cenozoic without the last Quaternary period. The Quaternary period occupies a special position. This is the shortest period, but many events took place in it, the traces of which are better preserved than others.

Eon (eonoteme)	Era (erathema)	(system)		years ago	Main events
Phanerozoic	Cenozoic	Quaternary (Anthropogenic)			End of the Ice Age. Rise of civilizations
Pleistocene		Extinction of many large mammals. The emergence of modern man
Neogene

Paleogene	Oligocene	33.9 ± 0.1 million	Appearance of the first great apes.
	55.8 ± 0.2 million	The emergence of the first "modern" mammals.
Paleocene	65.5 ± 0.3 million
		145.5 ± 0.4 million	The first placental mammals. Dinosaur extinction.
	199.6 ± 0.6 million	The appearance of marsupial mammals and the first birds. Rise of the dinosaurs.
Triassic	251.0 ± 0.4 million	The first dinosaurs and egg-laying mammals.
Paleozoic	Permian	299.0 ± 0.8 million	About 95% of all existing species died out (Mass Permian extinction).
Coal	359.2 ± 2.8 million	The appearance of trees and reptiles.
Devonian	416.0 ± 2.5 million	The appearance of amphibians and spore plants.
Silurian	443.7 ± 1.5 million	Exit of life to land: scorpions; emergence of jawed
Ordovician	488.3 ± 1.7 million	Racoscorpions, the first vascular plants.
Cambrian	542.0 ± 1.0 million	The emergence of a large number of new groups of organisms ("Cambrian explosion").
Precambrian
Proterozoic	Neoproterozoic	Ediacaran		The first multicellular animals.
cryogeny		One of the largest glaciations on Earth
		Beginning of the disintegration of the supercontinent Rodinia
Mesoproterozoic			Supercontinent Rodinia, superocean Mirovia
		First multicellular plants (red algae)

Paleoproterozoic	Statery
Orosirium

		Oxygen catastrophe
	neoarchean
Mesoarchean
paleoarchaean
		The emergence of primitive unicellular organisms
catarchean		~4.6 billion years ago - the formation of the Earth.

Scale charts of the geochronological scale

Three chronograms are presented, reflecting different stages of the history of the earth on a different scale.

1. The top diagram covers the entire history of the earth;

2. The second - Phanerozoic, the time of the mass appearance of various forms of life;

3. Lower - Cenozoic, the period of time after the extinction of the dinosaurs.

Hosted on Allbest.ru

Age of rocks and methods for their determination

The concept of geological time. Degeological and geological stages of the Earth's development. Age of sedimentary rocks. Periodization of the history of the Earth. General geochronological and stratigraphic scales. Methods for determining the isotopic age of rocks.

abstract, added 06/16/2013

Physical and geological processes

The internal structure of the Earth. The concept of the mantle as the geosphere of the Earth, which surrounds the core. The chemical composition of the Earth. The layer of low viscosity in the upper mantle of the Earth (asthenosphere), its role and significance. Earth's magnetic field. Features of the atmosphere and hydrosphere.

presentation, added 11/21/2016

The main characteristics of the planet

Modern ideas about the internal structure of the Earth. Radius of a heliocentric orbit. Experimental data on the structure of the globe. Earth's crust and geological chronology. Features of the geochronological scale. Processes that form the earth's crust.

abstract, added 11/11/2009

Evolutionary changes in the Earth's atmosphere

Features of the composition and structure of the Earth's atmosphere. The evolution of the earth's atmosphere, the process of its formation over the centuries. The appearance of the aquatic environment as the beginning of the geological history of the Earth. The content and origin of impurities in the atmosphere, their chemical composition.

abstract, added 11/19/2009

Paleomagnetic scale of reversals of the Earth's main magnetic field and the age of the ocean floor

Magnetization of linear sections of the oceanic crust during reversals of the main magnetic field, expansion and buildup of oceanic plates in rift zones. Drawing up a geochronological scale of paleomagnetic anomalies in the process of marine magnetic surveys.

abstract, added 08/07/2011

Characteristics of the main shells of the Earth

The main shells of the Earth: atmosphere, hydrosphere, biosphere, lithosphere, pyrosphere and centrosphere. The composition of the Earth and its physical structure. Geothermal regime of the Earth and its specificity. Exogenous and endogenous processes and their influence on the solid surface of the planet.

abstract, added 02/08/2011

Methods of historical geology and the structure of the earth's crust

The concept and tasks of historical geology. Paleontological and non-paleontological methods for reconstructing the geological past. Determination of the relative age of igneous rocks. Periodization of the history of the Earth. The concept of stratigraphic units.

abstract, added 05/24/2010

Modern mineralogical models of the Earth's mantle

Model of the structure of the Earth. The work of the Australian seismologist K.E. Bullen. The composition of the upper mantle and the mantle below the boundary of 670 km. The modern structure of the Earth. Examples of the distribution of velocity anomalies in the mantle according to seismic tomography data at different depths.

presentation, added 04/20/2017

The internal structure of the Earth

The formation of the Earth according to modern cosmological concepts. Structure model, basic properties and their parameters characterizing all parts of the Earth. The structure and thickness of the continental, oceanic, subcontinental and suboceanic crust.

abstract, added 04/22/2010

The internal structure of the Earth

The creation of a model of the internal structure of the Earth as one of the greatest achievements of science in the 20th century. Chemical composition and structure of the earth's crust. Characteristics of the composition of the mantle. Modern ideas about the internal structure of the Earth. Composition of the Earth's core.

abstract, added 03/17/2010

GEOLOGICAL CHRONOLOGY

A very important characteristic of rocks is their age. As shown above, many properties of rocks, including engineering-geological ones, depend on it. In addition, on the basis of studying, first of all, the age of rocks, historical geology recreates the patterns of development and formation of the earth's crust. An important section of historical geology is geochronology - the science of the sequence of geological events in time, their duration and subordination, which it establishes by determining the age of rocks based on the use of various methods and geological disciplines. The relative and absolute age of rocks is distinguished.

In assessing relative age, older and younger rocks are distinguished by highlighting the time of an event in the history of the Earth in relation to the time of another geological event. Relative age is easier to determine for sedimentary rocks in their undisturbed (close to horizontal occurrence) occurrence, as well as for volcanic and less often metamorphic rocks interbedded with them.

The stratigraphic (stratum - layer) method is based on the study of the sequence of occurrence and the relationship of layers of sedimentary deposits, based on the principle of superposition: each overlying layer is younger than the lower one.

It is used for strata with undisturbed horizontal occurrence of layers (Fig. 22). This method should be carefully applied when the layers are folded; first, their tops and bottoms must be determined. Young is the layer 3 , and the layers 1 and 2 - more ancient.

Lithologo — petrographic method is based on the study of the composition and structure of rocks in adjacent sections of wells and the identification of rocks of the same age - correlation of sections . Sedimentary, volcanic and metamorphic rocks of the same facies and age, such as clays or limestones, basalts or marbles, will have similar textural and structural features and composition.

Geological time scale for the history of life on Earth

Older rocks tend to be more altered and compacted, while younger ones are slightly altered and porous. It is more difficult to use this method for thin continental deposits, the lithological composition of which changes rapidly along strike.

The most important method for determining relative age is paleontological ( biostratigraphic ) method , based on the allocation of layers containing various complexes of fossil remains of extinct organisms. The method is based on the principle of evolution : life on Earth develops from simple to complex and does not repeat itself in its development. The science that establishes the pattern of the development of life on Earth by studying the remains of fossil animals and plant organisms - fossils ( fossils) contained in the strata of sedimentary rocks is called paleontology. The time of formation of one or another rock corresponds to the time of death of organisms, the remains of which were buried under layers above the accumulated sediments. The paleontological method makes it possible to determine the age of sedimentary rocks in relation to each other, regardless of the nature of the occurrence of layers, and to compare the age of rocks occurring in distant parts of the earth's crust. Each segment of geological time corresponds to a certain composition of life forms or guiding organisms (Fig. 23-29). Leading fossils ( forms ) lived for a short period of geological time on vast areas, as a rule, in reservoirs, seas and oceans. Starting from the second half of the twentieth century. began to actively apply the micropaleontological method, including spore — pollen, to study organisms invisible to the eye. On the basis of the paleontological method, schemes of the evolutionary development of the organic world were drawn up.

Thus, based on the above methods for determining the relative age of rocks by the end of the 19th century. a geochronological table was compiled, which includes subdivisions of two scales: stratigraphic and corresponding geochronological.

Stratigraphic subdivision (unit) - a set of rocks that make up a certain unity in terms of a set of features (features of the material composition, organic remains, etc.), which allows you to distinguish it in the section and trace about the area. Each stratigraphic unit reflects the peculiarity of the natural geological stage of the development of the Earth (or a separate area), expresses a certain geological age and is comparable to a geochronological unit.

Geochronological (geohistorical) scale - a hierarchical system of geochronological (temporal) divisions, equivalent to units of the general stratigraphic scale. Their ratio and subdivision is shown in Table. fifteen.

isolated in the UK, Perm - in Russia, etc. (Table 16).

Absolute age - the duration of the existence (life) of the breed, expressed in years - in time intervals equal to the modern astronomical year (in astronomical units). It is based on measuring the content of radioactive isotopes in minerals: 238U, 232Th, 40K, 87Rb, 14C, etc., their decay products and knowledge of the experimentally revealed decay rate. The latter has a half-life – the time it takes for half of the atoms of a given unstable isotope to decay. The half-life varies greatly for different isotopes (Table 17) and determines the possibilities of its application.

Methods for determining the absolute age got their name from the products of radioactive decay, namely: lead (uranium-lead), argon (potassium-argon), strontium (rubidium-strontium), etc. The most commonly used potassium-argon method, since the 40K isotope contained in many minerals (mica, amphiboles, feldspars, clay minerals), decomposes with the formation of 40Ar and has a half-life of 1.25 billion years. Calculations made using this method are often verified by the strontium method. In these minerals, potassium is isomorphically replaced by 87Rb, which, upon decay, transforms into the 87Sr isotope. With the help of 14C, the age of the youngest Quaternary breeds is determined. Knowing how much lead is formed from 1 g of uranium per year, determining their combined content in a given mineral, one can find the absolute age of the mineral and the rock in which it is located.

The use of these methods is complicated by the fact that rocks during their "life" experience various events: magmatism, metamorphism, and weathering, during which the minerals "open", change and lose the isotopes and decay products partially contained in them.

Therefore, the term "absolute" age used is convenient to use, but is not absolutely accurate for the age of rocks. It is more correct to use the term "isotopic" age. A systematic correlation is made between the subdivisions of the relative geochronological table and the absolute age of the rocks, which is still being refined and given in the tables.

Geologists, builders and other professionals can obtain information about the age of rocks by studying geological maps or related geological reports. On the maps, the age of rocks is shown by the letter and color that are accepted for the corresponding subdivision of the geochronological table. Comparing the relative age of specific rocks shown by letter and color with the absolute age of the unified geochronological table, we can assume the absolute age of the studied rocks. Civil engineers must have an understanding of the age of rocks and its designation, and also use them when reading geological documentation (maps and sections) compiled when designing buildings and structures.

Of particular interest is the Quaternary period (Table 18). The deposits of the Quaternary system cover the entire earth's surface with a continuous cover, their strata contain the remains of an ancient man and his household items. In these sequences, various deposits (facies) alternate and replace each other in area: eluvial, alluvial , moraine and fluvioglacial, lacustrine — marsh. Deposits of alluvial gold and other valuable metals are confined to alluvium. Many breeds of the Quaternary system are raw materials for the production of building materials. A large place is occupied by deposits of the cultural layer , resulting from human activity. They are distinguished by considerable friability and great heterogeneity. Its presence can complicate the construction of buildings and structures.

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 natural chronological order: from oldest to newest. 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.

New geological period

The International Stratigraphic Committee (ISC) decided at the end of 2000 - consider the time since the second quarter of 2001 as a new geological period as part of the Cenozoic era. In this regard, we have already begun to receive questions to the editorial office:

Why is this needed?

Why was the Quaternary period so short - only 1-2 million years (according to various estimates), while all previous periods lasted tens of millions of years?

What will be the name and designation of the period? (Those who read about the proposed period name ask for an explanation.)

Why exactly from the second quarter, and not from the beginning of some year?

We will try to answer these questions.

IN AND. Vernadsky believed that human activity becomes a powerful geological factor, commensurate with natural factors. The validity of this became especially evident towards the end of the 20th century. The movement of huge masses of rock during mining, artificial intervention in the geochemical and hydrogeological regimes of the earth's crust required a strict account of all this impact. Therefore, the MSC decided to record the state of the earth's crust at some point in order to keep a record of its changes as a result of technogenic impact starting from that moment. It would be logical to make this moment the beginning of 2000 or 2001, but by the beginning of 2000 they did not have time to get a clear picture of the state of the interior of the planet as a whole, and by September 2000 it turned out that the necessary documentation did not have time even by the beginning of 2001. That's the start of the second quarter.

Analyzing the geochronological table, you immediately notice that the duration of eras and periods gradually decreases as we approach the present. They wrote about the general acceleration of geological processes, but most likely this is due to the fact that we know more about later geological periods, more traces of them remain, so periodization can be done with greater fractionality. As for the most recent time, human intervention has indeed accelerated many processes.

Earlier in geology, igneous and metamorphic rocks were considered primary, sedimentary - secondary. When in the middle of the XVIII century. younger sedimentary rocks were isolated, they were called tertiary, they included the Paleogene and Neogene, which from half a century ago constituted a single tertiary system, which was formed during the eponymous tertiary period. In 1829, the "youngest" deposits were identified, they were called Quaternary; accordingly, the Quaternary period was also singled out; its second name is anthropogen, in Greek man-bearing.

Geological scale

Therefore, the MSC did not suffer for a long time with the name of the new period: without further ado, the period was called fivefold, or technogenic(however, here the connotation is somewhat different: not “giving birth to technology”, but “born by technology”). The Quaternary period is denoted by the symbol Q (Latin quartus- fourth). Fivefold wanted to be called by analogy quintus(fifth), but they realized it in time: they would have to designate it with the same letter Q, only, probably, crossed out, like the crossed out P - this is the Paleogene (not to be confused with the Permian), the crossed out C - the Cambrian (unlike the Carboniferous); everyone who has typed these characters on a typewriter, and especially on a computer, knows how inconvenient it is. We decided to take as a basis not Latin, but English or German and designate the period F ( five or fu..nf), there is a blessing and a precedent: the Cretaceous period is denoted by the letter K from the German Kreide- a piece of chalk.

Now all states are obliged to submit to the MSC every 5 years a report on the volume of mining operations, on which rocks, in what quantity, and from where they were moved, where they formed strata of fivefold, or technogenic, deposits. In Russian terminology, that's right - technogenic. The deposits and landforms formed by man are called anthropogenic, and the deposits and forms formed by any processes during the Quaternary period, or the Anthropogen, are called Anthropogenic. Hence it follows that the rocks formed in the fivefold period in a natural way, without human intervention, can also be called technogenic.

In a word, a very serious decision has been made. How effective will be its results, time will tell.

The longest geological period on the planet

Approximately 2500 million years ago, the Archaean was replaced by a new eon - the Proterozoic. And it was he who subsequently became the longest geological period in the history of our planet, lasting almost 2000 million years and including three long eras: Paleoproterozoic, Mesoproterozoic and Neoproterozoic, during which significant changes took place on the Earth.

Dividing the history of the Earth into eras and periods

And the first significant event that occurred at the beginning of the longest geological period on the planet, or rather in the era of the Paleoproterozoic, the siderian period, that is, about 2.4 billion years ago, is, of course, an oxygen catastrophe, which entailed significant changes in the composition of the atmosphere . So, it was in the earliest geological period of the Proterozoic, due to the extinction of the activity of oceanic and terrestrial volcanoes, that the biochemical composition of the world ocean began to change completely, as a result of which oxygen, released by already existing cyanobacteria, began to be produced even more rapidly, leaving local pockets and oxidizing all around. Upon completion of the oxidation process, the atmosphere finally began to be enriched with free oxygen, and it was this factor that led to a cardinal change in the composition of the atmosphere. It is noteworthy that there is no exact data on its original composition, and the fact that everything changed after the oxygen catastrophe is evidenced by the found ancient rocks that have not undergone oxidation processes.

After these events, the world was literally “turned inside out”, because if earlier it was filled with anaerobic microorganisms that could exist exclusively outside the oxygen environment, pushing aerobic microorganisms into local pockets, then a gradual increase in the level of oxygen in the atmosphere led to the opposite picture. However, this does not mean at all that the rapidly changing atmosphere even remotely resembled the modern one, because only 400 million years after the start of the oxygen catastrophe, the content of free oxygen in its composition reached ten percent of the volume of O2 that can be observed today (this milestone was called the point Pasteur). It is noteworthy that it was previously believed that this figure was exactly 10 times less, however, as it turned out later, both figures were quite enough to ensure the full functioning of rapidly multiplying unicellular organisms. Nevertheless, these processes entailed another colossal test for the planet - the Ice Age, which developed as a result of the massive absorption of methane by rapidly released free oxygen.

And although at that time the luminosity of the Sun for our planet increased on average by as much as 6 percent, it could not warm up due to a shortage of methane, which is capable of producing a powerful greenhouse effect, according to one theory, ice covered the entire globe at that time, literally turning it into a giant snowball. It is noteworthy that by that period the volume of the world ocean that exists in modern times had already formed, and after the end of the Huron glaciation period, which occurred approximately 2.1 billion years ago, more complex organisms in the form of sponges and fungi began to appear on Earth.

In addition, the soil began to actively form, the main role in this process was played by the vital activity of bacteria and unicellular algae, now known as prokaryotes. Another significant event in this era of the Earth's existence was the first relative stabilization of the continents, as a result of which the once-existing super-continent Rodinia began to form, although it was far from the only one in its entire history. The end of the formation of this formation is approximately dated to 1150 million years BC, but by the end of the Proterozoic it again disintegrated.

In fact, Rodinia existed for no more than 250 million years, and after the collapse, about 8 large fragments remained from it, which later became the basis for modern continents. During this period, complex organisms already existed on the planet, as evidenced by their numerous remains. Unfortunately, the collapse of the super-continent was not the last test for the Earth of the Paleozoic era, because soon its surface was again covered with ice, which claimed hundreds of thousands of lives of animals that had appeared by that time.

It is noteworthy that the found remains of animals, most likely dead from another global cooling, had a solid skeleton. This fact indicates that evolution during the Proterozoic period was striking in the scale of its development.

The history of the development of the Earth for the convenience of study is divided into four eras and eleven periods. The two most recent periods are in turn divided into seven systems or eras.

The earth's crust is stratified, i.e. the various rocks that make it up lie on top of each other in layers. As a rule, the age of rocks decreases towards the upper layers. The exception is the areas with disturbed due to the movements of the earth's crust, the occurrence of layers. William Smith in the 18th century noticed that during the geological periods of time, some organisms have significantly advanced in their structure.

According to modern estimates, the age of the planet Earth is approximately 4.6 - 4.9 10 years. These estimates are based mainly on the study of rocks by radiometric dating methods.

ARCHEUS. Not much is known about life in the Archean. The only animal organisms were cellular prokaryotes - bacteria and blue-green algae. The products of the vital activity of these primitive microorganisms are also the most ancient sedimentary rocks (stromatolites) - calcareous formations in the form of pillars, found in Canada, Australia, Africa, the Urals, and Siberia. Sedimentary rocks of iron, nickel, manganese have a bacterial basis. Many microorganisms are active participants in the formation of colossal, as yet little explored mineral resources at the bottom of the World Ocean. The role of microorganisms is also great in the formation of oil shale, oil and gas.

Geological table of the Earth

Blue-green, bacteria quickly spread in the Archaean and become the masters of the planet. These organisms did not have a separate nucleus, but a developed metabolic system, the ability to reproduce. Blue-green, in addition, possessed the apparatus of photosynthesis. The appearance of the latter was the largest aromorphosis in the evolution of living nature and opened one of the ways (probably specifically terrestrial) for the formation of free oxygen.

By the end of the Archean (2.8-3 billion years ago), the first colonial algae appeared, the fossilized remains of which were found in Australia, Africa, etc.

The most important stage in the development of life on Earth is closely related to the change in the concentration of oxygen in the atmosphere, the formation of the ozone screen. Thanks to the vital activity of blue-greens, the content of free oxygen in the atmosphere has increased markedly. The accumulation of oxygen led to the emergence of a primary ozone screen in the upper layers of the biosphere, which opened horizons for flourishing.

PROTEROZOI. The Proterozoic is a huge stage in the historical development of the Earth. During its course, bacteria and algae reach an exceptional flowering, with their participation, the processes of sedimentation were intensively going on. As a result of the vital activity of iron bacteria in the Proterozoic, the largest iron ore deposits were formed.

At the turn of the early and middle Riphean, the dominance of prokaryotes is replaced by the flourishing of eukaryotes - green and golden algae. From unicellular eukaryotes, multicellular ones with a complex organization and specialization develop in a short time. The oldest representatives of multicellular animals have been known since the late Riphean (700-600 million years ago).

Now we can state that 650 million years ago, the Earth's seas were inhabited by a variety of multicellular organisms: solitary and colonial polyps, jellyfish, flatworms, and even the ancestors of modern annelids, arthropods, molluscs, and echinoderms. Some forms of fossil animals are now difficult to assign to known classes and types. Among plant organisms at that time, unicellular organisms predominated, but multicellular algae (green, brown, red), fungi also appear.

PALEOZOIC. By the beginning of the Paleozoic era, life had passed perhaps the most important and difficult part of its journey. Four kingdoms of living nature were formed: prokaryotes, or pellets, mushrooms, green plants, animals.

The ancestors of the kingdom of green plants were unicellular green algae, common in the seas of the Proterozoic. Along with floating forms among the bottoms, there appeared those attached to the bottom. A fixed lifestyle required the dismemberment of the body into parts. But the acquisition of multicellularity, the division of a multicellular body into parts that perform various functions, turned out to be more promising.

Of decisive importance for further evolution was the emergence of such an important aromorphosis as the sexual process.

How and when did the division of the living world into plants and animals occur? Do they have the same root? Disputes of scientists around this issue do not subside even today. Perhaps the first animals evolved from a common stem of all eukaryotes or from single-celled green algae.

CAMBRIAN- flowering of skeletal invertebrates. During this period, another period of mountain building took place, the redistribution of land and sea area.

The climate of the Cambrian was temperate, the continents were unchanged. Only bacteria and blue-greens still lived on land. The seas were dominated by green and brown algae attached to the bottom; diatoms, golden algae, and euglena algae swam in the water column.

As a result of the increase in the washout of salts from the land, marine animals have been able to absorb mineral salts in large quantities. And this, in turn, opened up wide ways for them to build a rigid skeleton.

The oldest arthropods - trilobites, outwardly similar to modern crustaceans - wood lice, have reached the widest distribution.

Very characteristic of the Cambrian is a peculiar type of multicellular animals - the archaeocyath, which died out by the end of the period. A variety of sponges, corals, brachiopods, and mollusks also lived at that time. Later, sea urchins appeared.

ORDOVIC. In the seas of the Ordovician, green, brown and red algae, numerous trilobites were diversely represented. In the Ordovician, the first cephalopods, relatives of modern octopuses and squids, appeared, brachiopods, gastropods spread. There was an intensive process of formation of reefs by four-beam corals and tabulates. Graptolites are widely used - hemichordates, combining the features of invertebrates and vertebrates resembling modern lancelets.

In the Ordovician, spore plants appeared - psilophytes, growing along the banks of fresh water bodies.

SILUR. The warm shallow seas of the Ordovician were replaced by large areas of land, which led to the drying up of the climate.

In the Silurian seas, graptolites lived out their lives, trilobites fell into decline, but cephalopods reached exceptional prosperity. Corals gradually replaced the archaeocyath.

In the Silurian, peculiar arthropods developed - giant crustaceans, reaching up to 2 m in length. By the end of the Paleozoic, the entire group of crustaceans almost died out. They resembled a modern horseshoe crab.

A particularly noteworthy event of this period was the appearance and distribution of the first representatives of vertebrates - armored "fish". These “fishes” only resembled real fish in shape, but belonged to another class of vertebrates - jawless or cyclostomes. They could not swim for a long time and mostly lay at the bottom of bays and lagoons. Due to a sedentary lifestyle, they were incapable of further development. Of the modern representatives of cyclostomes, lampreys and hagfishes are known.

A characteristic feature of the Silurian period is the intensive development of terrestrial plants.

One of the first terrestrial, or rather amphibious, plants were psilophytes, leading their lineage from green algae. In reservoirs, algae adsorb water and substances dissolved in it over the entire surface of the body, which is why they do not have roots, and the outgrowths of the body, resembling roots, serve only as attachment organs. In connection with the need to conduct water from the roots to the leaves, a vascular system arises.

The emergence of plants on dry land is one of the greatest moments of Evolution. It was prepared by the previous evolution of the organic and inorganic world.

DEVONIAN. Devon - the period of fish. The climate of the Devonian was more sharply continental, icing occurred in the mountainous regions of South Africa. In warmer regions, the climate changed towards greater desiccation, desert and semi-desert areas appeared.

In the seas of the Devonian, fish reached great prosperity. Among them were cartilaginous fish, fish with a bone skeleton appeared. According to the structure of the fins, bony fish are divided into ray-finned and lobe-finned. Until recently, it was believed that the crossopterans became extinct at the end of the Paleozoic. But in 1938, a fishing trawler delivered such a fish to the East London Museum and it was named coelacanth.

At the end of the Paleozoic, the most significant stage in the development of life was the conquest of land by plants and animals. This was facilitated by the reduction of sea basins, the rise of land.

Typical spore plants emerged from psilophytes: club mosses, horsetails, ferns. The first forests appeared on the earth's surface.

By the beginning of the Carboniferous, there was a noticeable warming and humidification. In the vast valleys and tropical forests, in the conditions of continuous summer, everything grew rapidly upwards. Evolution has opened a new way - reproduction by seeds. Therefore, gymnosperms picked up the evolutionary baton, and spore plants remained a side branch of evolution and receded into the background.

The emergence of vertebrates on land occurred in the late Devonian period, after the land conquerors - psilophytes. At this time, the air was already mastered by insects, and the descendants of lobe-finned fish began to spread over the earth. The new way of transportation allowed them to move away from the water for some time. This led to the emergence of creatures with a new way of life - amphibians. Their most ancient representatives - ichthyoskhegi - were found in Greenland in Devonian sedimentary rocks.

The heyday of ancient amphibians is dated to the Carboniferous. It was during this period that stegocephals were widely developed. They lived only in the coastal part of the land and could not conquer the inland massifs located far from water bodies.

Portal for the student. Self-training

Geological table

Eras and periods

Stages of the Earth's development

catarchean

archaeus

Proterozoic

Phanerozoic

And now about everything in more detail:

GEOLOGICAL CHRONOLOGY

Geological time scale for the history of life on Earth

Archean era

Proterozoic era

Palaeozoic

Cambrian Period (Cambrian)

Ordovician period (Ordovician)

Silurian (30 Ma)

Devonian (60 Ma)

Carboniferous period

Perm (55 million)

Mesozoic era

Triassic

Jurassic period

Cretaceous period (70 million years)

Cenozoic era

Paleogene

Neogene (about 23.5 Ma)

Anthropogene (1.5 Ma)

New geological period

Geological scale

The longest geological period on the planet

Dividing the history of the Earth into eras and periods

Geological table of the Earth

RELATED ARTICLES