Archean era (Archean) - from 4.0 to 2.5 billion years ago
Archean eon, archean (ancient Greek ρχαος - ancient) - one of the four eons (the period of time of geological history, during which the eonothem was formed, unites several eras) of the Earth's history, covering the time from 4.0 to 2.5 billion years ago.
The term "archaea" was proposed in 1872 by the American geologist James Dana.
Archaeus is divided into four eras (from the most recent to the earliest):
Neoarcheus,
Mesoarchean,
Paleoarchean,
Eoarcheus.
At this time, there was still no oxygen atmosphere on Earth, but the first anaerobic organisms appeared. In the same period, many currently existing deposits of sulfur, graphite, iron and nickel are actively formed.
Archeus and the next Proterozoa enter the time period Precambrian.
Hydrosphere and atmosphere. Climate
At the very beginning of the Archean era, there was little water on Earth; instead of a single ocean, there were only scattered shallow-water basins. The water temperature reached 70-90 ° C, which could be observed only if the Earth had a dense carbon dioxide atmosphere at that time. Indeed, of all possible gases, only CO2 could create an increased atmospheric pressure (for the Archaean - 8-10 bar).
There was very little nitrogen in the atmosphere of the early Archean (10-15% of the volume of the entire Archean atmosphere), there was practically no oxygen at all, and gases such as methane are unstable and quickly decompose under the influence of hard radiation from the Sun (especially in the presence of a hydroxyl ion, also while arising in a humid atmosphere).
The temperature of the Archean atmosphere during the greenhouse effect reached almost 120 ° C. If at the same pressure the atmosphere in the Archean consisted, for example, only of nitrogen, then the surface temperatures would be even higher and reach 100 ° С, and the temperature with the greenhouse effect would exceed 140 ° С.
About 3.4 billion years ago, the amount of water on Earth increased significantly and the World Ocean emerged, overlapping the crests of the mid-ocean ridges. As a result, the hydration of the basalt oceanic crust noticeably increased, and the rate of increase in the partial pressure of CO2 in the Late Archean atmosphere slightly decreased. The most radical drop in CO2 pressure occurred only at the boundary between the Archean and Proterozoic after the separation of the Earth's core and the associated sharp decrease in the tectonic activity of the Earth.
Due to this, in the Early Proterozoic, the melting of oceanic basalts decreased just as sharply. The basaltic layer of the oceanic crust became noticeably thinner than it was in the Archean, and a serpentinite layer, the main and constantly renewed reservoir of bound water on Earth, formed under it for the first time.
Flora and fauna
The Archean deposits lack the skeletal fauna, which serves as the basis for constructing the stratigraphic scale of the Phanerozoic; nevertheless, there are quite a lot of various traces of organic life here.
These include the waste products of blue-green algae - stromatolites, which are coral-like sedimentary formations (carbonate, less often silicon), and the waste products of bacteria - oncoliths.
The first reliable stromatolites were discovered only at the turn of 3.2 billion years ago in Canada, Australia, Africa, the Urals and Siberia. Although there is evidence of the discovery of the remains of the first prokaryotes and stromatolites in sediments aged 3.8-3.5 billion years, in Australia and South Africa.
Also, in the siliceous rocks of the early Archean, peculiar filamentous algae were found, which are well preserved, in which you can observe the details of the cellular structure of the body. At many stratigraphic levels, there are the smallest rounded bodies (up to 50 m in size) of algal origin, previously taken for spores. They are known as acritarch or spheromorphids.
The Archean fauna is much poorer than the flora. Separate indications of the presence of animal remains in the Archean rocks refer to objects that are apparently of inorganic origin (Aticocania Walcott, Tefemar kites Dons, Eozoon Dawson, Brooksalla Bassler) or are products of stromatolite leaching (Carelozoon Metzger). Many Archean fossils are not fully deciphered (Udokania Leites) or do not have an exact link (Xenusion querswalde Pompecki).
Thus, in the Archean zone, prokaryotes of two kingdoms were reliably found: bacteria, mainly chemosynthetic, anaerobic, and photosynthetic cyanobionts that produce oxygen. It is not excluded that the first eukaryotes from the kingdom of fungi, morphologically similar to yeast fungi, also appeared in the Archean.
The oldest bacterial biocenoses, i.e. the communities of living organisms, which included only producers and destructors, looked like mold films (so-called bacterial mats) located at the bottom of water bodies or in their coastal zone. Volcanic regions often served as oases of life, where hydrogen, sulfur and hydrogen sulfide, the main donors of electrons, came to the surface from the lithosphere.
For almost the entire Archean era, living organisms were unicellular, highly dependent on natural factors. And only at the turn of the Archean and Proterozoic there were two major evolutionary events: the sexual process and multicellularity appeared.
Haploid organisms (bacteria and blue-green algae) have one set of chromosomes. Each new mutation immediately manifests itself in their phenotype. If the mutation is useful, it is preserved in the process of natural selection, if it is harmful, it is eliminated.
Haploid organisms are constantly adapting to the environment, but they do not develop fundamentally new signs and properties. The sexual process sharply increases the ability to adapt to environmental conditions, due to the creation of countless combinations in chromosomes.
Diploidy, which arose simultaneously with the formed nucleus, allows mutations to be preserved and used as a reserve of hereditary variability for further evolutionary transformations.
The Archean era is the oldest, earliest period in the history of the earth's crust. The first living organisms arose in the Archean era. They were heterotrophs and used organic compounds as food. The end of the Archean era is the time of the formation of the earth's core and a strong decrease in volcanic activity, which allowed the development of life on the planet.
Earth's crust The lower period of the Archean era - Eoarchean 4 - 3.6 billion years ago. About 4 billion years ago the earth formed like a planet. Almost the entire surface was covered with volcanoes and rivers of lava flowed everywhere. Lava, erupting in large quantities, formed continents and oceanic trenches, mountains and plateaus. Constant volcanic activity, exposure to high temperatures and high pressure led to the formation of various minerals: various ores, building stone, copper, aluminum, gold, cobalt, iron, radioactive minerals and others. Approximately 3.8 billion years ago The first reliably confirmed igneous and metamorphic rocks such as granite, diorite and anorthosite were formed on Earth. These rocks were found in a wide variety of places: on the island of Greenland, within the Canadian and Baltic shields, etc.
The next period of the Archean era is Paleoarchean 3.6 - 3.2 billion years ago. It is the time of the formation of the first supercontinent in the history of the Earth - Valbaru and the united World Ocean, which changed the structure of the ridges of the oceanic ridges, which led to the process of increasing the amount of water on Earth, and the volume of CO2 in the atmosphere began to decrease.
Atmosphere and climate of the Archean era At the very beginning of the Archean era, there was little water on Earth; instead of a single ocean, there were only shallow-water basins that were not interconnected. The atmosphere of the Archean era was mainly composed of carbon dioxide CO2 and its density was much higher than today. Thanks to the carbon dioxide atmosphere, the water temperature reached 80-90 ° C. The nitrogen content was low, on the order of 10-15%. There was almost no oxygen, methane and other gases. The atmosphere temperature reached 120 ° С
Flora and fauna of the Archean era The Archean era is the time of the birth of the first organisms. The first inhabitants of our planet were anaerobic bacteria. The most important stage in the evolution of life on Earth is associated with the emergence of photosynthesis, which determines the division of the organic world into plant and animal. The first photosynthetic organisms were prokaryotic (prenuclear) cyanobacteria and blue-green algae. The eukaryotic green algae that appeared then released free oxygen from the ocean into the atmosphere, which contributed to the emergence of bacteria that can live in an oxygen environment. At the same time - on the border of the Archean Proterozoic era, two more major evolutionary events occurred - the sexual process and multicellularity appeared. Haploid organisms (bacteria and blue-green) have one set of chromosomes. Each new mutation immediately manifests itself in their phenotype. If the mutation is useful, it is preserved by selection; if it is harmful, it is eliminated by selection. Haploid organisms are constantly adapting to the environment, but they do not develop fundamentally new signs and properties. The sexual process dramatically increases the ability to adapt to environmental conditions, due to the creation of countless combinations in chromosomes
Archean climate
In the 19th century, the prevailing idea was that in ancient times, the temperature on the earth's surface was maintained mainly by internal heat. Apparently, this is true for the earliest stages of the Earth's development: lunar and nuclear. but beginning with archean era When the hydrosphere and atmosphere existed, the leading role in the distribution of heat on the planet's surface is apparently played by the energy of the Sun. If so, then on Earth already in the Archean erathere should be climatic zoning, since the amount of solar heat depends on the latitude of the area.
The presence of climatic zones in the Archeancan be confirmed by some, albeit isolated, facts. These include, in particular, the finds of ancient metamorphosed glacial deposits - tillits... Their remains are found, for example, in North America, in Central and South Africa, in South Australia, in Siberia. The dimensions of ancient glaciers, their centers and the direction of movement of glaciers have not yet been determined. In areas of North America, it is known that traces of glaciers can be traced in latitudinal direction for almost 1,850 kilometers and 370 kilometers north of present latitude 42 °.
It was also found that the power early Proterozoic tillites reaches 160-180 meters. The stratum consists of alternating tillite horizons and clay shales, the accumulation of which took place already in lacustrine or river conditions. Consequently, the glacial epochs alternated with interglacial epochs, when the size of the glacier decreased and lakes of glacial origin appeared in its place.
According to N. M. Strakhov, the ancient glaciation was mountainous. Such glaciers, which we see now in Antarctica, with an area of \u200b\u200bup to 13 million square kilometers, probably did not exist in the Archean and Proterozoic eras, since there were not yet extensive continental massifs. Most likely, glaciers covered the tops of individual mountains or mountain ranges and descended in tongues to the foothills.
Along with glacial deposits, metamorphosed organic remains, obviously of plant origin (most likely algae), are also found in ancient strata - these are various graphite shales, graphite inclusions in other rocks. Indirectly, the development of primitive vegetation in ancient oceans indicates a relatively warm climate that existed in some areas of the globe. It is possible that the warm climatic zone was located along the coast of the Tethys Ocean. Based on these scanty data, we can conclude about the climatic zoning that existed on Earth 2-3 billion years ago. How climatic zones passed, and which zones existed - practically nothing is known about this so far.
The course and direction of the process of the emergence of species in accordance with the main provisions of Charles Darwin's theory of evolution are supported by data from various branches of biology, including data from the field of paleontology, which serve as material evidence, since they are based on the study of fossil remains of once living organisms. As a result of the progressive development of life, one groups of organisms were replaced by others, while the third changed little, and the fourth died out. On the basis of the finds of fossil forms in the sediments of the earth's strata, it is possible to trace the true history of living nature. This is how the paleontological series of the horse (V.O. Koralevsky), the elephant, some birds, mollusks, and others were created - from the most primitive initial forms to their modern representatives. The use of the radioisotope method makes it possible to determine with great accuracy the age of rocks in places of occurrence of paleontological remains and the age of fossil organisms.
On the basis of paleontological data, the entire history of life on Earth is subdivided into eras and periods.
Table 1. Geochronological scale
| Eras | their duration, million years | Fauna and flora |
| name and duration, million years | age, million years |
|
| Cenozoic (new life) 60-70 | 60-70 | gene 1.5-2 Fauna and flora have taken on a modern look |
| Upper Tertiary (Neogene) 25 Lower Tertiary (Paleogene) 41 The dominance of mammals, birds. The appearance of lemurs and dol-gopats - low-organized primates, later - parapithecus, driopithecus. The flourishing of insects. The extinction of large reptiles continues. Many groups of cephalopods are disappearing. Dominance of angiosperms. Reducing the flora of gymnosperms |
||
| Mesozoic (middle life) 173 | 240 ± 10 | Cretaceous 70 Jurassic 58 Triassic 45 The appearance of higher mammals and true birds, although toothy birds are still common. Bony fish predominate. The number of ferns and gymnosperms is sharply decreasing. The emergence and distribution of angiosperms. Dominance of reptiles. Archeopteryx appears. The flowering of cephalopods. Dominance of gymnosperms The beginning of the flourishing of reptiles. The appearance of the first mammals, true teleost fish. The disappearance of seed ferns |
| Paleozoic (ancient life) 330 | 570 | Permsky 45 Coal (carbon) 55-75 Rapid development of reptiles. The emergence of animal-like reptiles. Extinction of trilobites. The disappearance of the forests of the Carboniferous period. The emergence and development of gymnosperms. The flowering of amphibians. The emergence of the first reptiles. The appearance of scorpions, spiders, flying forms of insects. Reducing the number of trilobites. Development of higher spore and seed ferns. The predominance of ancient lyre and horsetail. Mushroom development |
| Devonian sky 50-70 The flowering of corymbs. Emergence cross-finned fishes and stegocephals. The emergence of fungi. Development, and then the extinction of the psilophytes. Terrestrial spread of higher controversial |
||
| Silurius sky 30 Lush coral development, three |
||
| Ordovician sky 60 Flourishing of marine invertebrates, trilobites, molluscs, archaeocyat. |
||
| Kemb- rian 70 Widespread algae |
||
| Prothero zoyskaya (ran her life) 2000 |
2600 + 100 |
All types of invertebrates are represented. The emergence of primary chordates - a subtype of cranial |
| Archean (the most ancient nya) 900 |
3500 | The traces of life are insignificant. Remnants of bacteria and unicellular algae |
1. Archean era - the most ancient stage in the history of the Earth, when life arose in the waters of the primary seas, whichwas originally presented precellular its forms and the first cellular organisms. Wasp analysisthis age shows that bacteria and blue-greens lived in the aquatic environment.
2 ... Proterozoic era. On the verge of the Archean and Proterozoic eras, the structure and function of organisms became more complex: multicellularity, a sexual process that increased the genetic heterogeneity of organisms and provided extensive material for selection, became more diverse, photosynthetic plants became more diverse. The multicellularity of organisms was accompanied by an increase in the specialization of cells, their association into tissues and functional systems.
It is rather difficult to trace in detail the evolution of animals and plants during the Proterozoic era due to the recrystallization of sedimentary rocks and the destruction of organic remains. In the sediments of this era, only imprints of bacteria, algae, lower types of invertebrates and lower chordates. A major step in evolution was the emergence of organisms with a bilateral symmetry of the body, differentiated into the anterior and posterior parts, left and right sides, the isolation of the dorsal and abdominal surfaces. The dorsal surface in animals served as protection, and on the abdominal surface were the mouth and organs for capturing food.
3. Paleozoic era. The fauna and flora reached a great variety, terrestrial life began to develop.
In the Paleozoic, six periods are distinguished: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian. In the Cambrian period, life was concentrated in water (it covered a significant part of our planet) and is represented by more perfect multicellular algae, which had a dissected thallus, thanks to which they synthesized organic substances more actively and were the original branch for terrestrial leafy plants. Invertebrates are widespread in the seas, including brachiopods, and from arthropods - trilobites. Archaeocyates, which formed reefs in ancient seas, were an independent type of two-layer animals of that period. They died out, leaving no descendants. Only inhabited land bacteriaand mushrooms.
In the Ordovician period, the climate was warm even in the Arctic. In the fresh and brackish waters of this period, planktonic seaweed, varied coral from the type of coelenterates, there were representatives of almost all types invertebrates including trilobites, molluscs, echinoderms. Bacteria were widely represented. The first representatives of jawless vertebrates appear - corymbose.
At the end of the Silurian period, due to mountain-building processes and a reduction in the area of \u200b\u200bthe seas, some of the algae found themselves in new environmental conditions - in shallow water bodies and on land. Many of them died. However, as a result of multidirectional variability and selection, individual representatives acquired traits that contributed to their survival in new conditions. The first terrestrial spore plants, psilophytes, appeared. They had a cylindrical stem about 25 cm in height, instead of leaves - scales. Their most important adaptations are the appearance of integumentary and mechanical tissues, root-like outgrowths - rhizoids,as well as an elementary conducting system.
In the Devonian, the number of psilophytes sharply decreased, they were replaced by their transformed descendants, higher plants - lymphoid, bryophyte and fern-like, which develop true vegetative organs (root, stem, leaf). The emergence of vegetative organs increased the efficiency of the function of individual parts of plants and their vitality as a harmoniously integral system. The emergence of plants on land preceded the emergence of animals. Plants accumulated biomass on Earth, and oxygen in the atmosphere. The first invertebrate inhabitants of land were spiders, scorpions, millipedes. There were many fish in the Devonian seas, among them - jaw armored, with an internal cartilaginous skeleton and an external strong shell, movable jaws, paired fins. Freshwater bodies inhabited cross-finned fish that had gill and primitive pulmonary respiration. With the help of fleshy fins, they moved along the bottom of the reservoir, and when they dried out, they crawled into other reservoirs. A group of cross-finned fish were the ancestors of ancient amphibians - stegocephalic. Stegocephals lived in swampy areas, came out onto land, but multiplied only in water.
In the Carboniferous period, giant ferns spread, which, in a warm, humid climate, settled everywhere. During this period, they flourished ancient amphibians.
During the Permian period, the climate became drier and colder, which led to the extinction of many amphibians. By the end of the period, the number of amphibian species began to decline sharply, and only small amphibians (newts, frogs, toads) have survived to this day. The tree-like spore ferns have been replaced by seed ferns, which gave rise to gymnosperms. The latter had a developed tap root system and seeds, and fertilization took place in the absence of water. The extinct amphibians were replaced by a more progressive group of animals descended from stegocephals - reptiles. They had dry skin, denser cellular lungs, internal fertilization, a supply of nutrients in the egg, protective egg membranes.
4. Mesozoic era includes three periods: Triassic, Jurassic, Cretaceous.
In the Triassic widespread gymnosperms, especially conifers, which have taken a dominant position. At the same time they spread widely reptiles: ichthyosaurs lived in the seas, plesiosaurs in the air - flying lizards, reptiles were represented in various ways on earth. Giant reptiles (brontosaurs, diplodocus, etc.) soon became extinct. At the very beginning of the Triassic, a group of small animals with a more perfect structure of the skeleton and teeth separated from the reptiles. These animals acquired the ability to live birth, a constant body temperature, they had a four-chambered heart and a number of other progressive organizational features. These were the first primitive mammals.
In the sediments of the Jurassic Mesozoic o6, the remains of the first bird were also found - archeopteryx. He combined in his structure the features of birds and reptiles.
In the Cretaceous period of the Mesozoic, a branch of plants that had an organ of seed reproduction - a flower - separated from the gymnosperms. After fertilization, the ovary of the flower turns into a fruit, so the developing seeds inside the fruit are protected by the pulp and shells from adverse environmental conditions. The variety of flowers of various adaptations for pollination and distribution of fruits and seeds allowed angiosperm (flowering) plants to spread widely in nature and take a dominant position. In parallel with them, a group of arthropods developed - insectswhich, being pollinators of flowering plants, contributed greatly to their progressive evolution. In the same period, appeared real birdsand placental mammals. Signs of a high degree of organization in them - constant body temperature | complete separation of arterial and venous blood flow, increased metabolism, perfect thermoregulation, and in mammals, in addition, viviparity, feeding of young with milk, the development of the cerebral cortex - allowed these groups to occupy a dominant position on Earth.
5. Cenozoic era it is subdivided into three periods: Paleogene, Neogene and Quaternary.
In the Paleogene, Neogene and early Quaternary period, flowering plants, thanks to the acquisition of numerous private adaptations, occupied most of the land and represented the subtropical and tropical flora. Due to the cold snap caused by the advance of the glacier, the subtropical flora retreated to the south. Terrestrial vegetation of temperate latitudes began to be dominated by deciduous trees, adapted to the seasonal rhythm of temperatures, and shrubs and herbaceous plants. The flowering of herbaceous plants occurs in the Quaternary period. Warm-blooded animals are widespread:
birds and mammals. During the ice age, cave bears, lions, mammoths, woolly rhinos lived, which gradually died out after the retreat of glaciers and the warming of the climate, and the animal world acquired its modern appearance.
The main event of this era is the formation of man. By the end of the Neogene, small tailed mammals lived in the forests - lemurs and tarsiers.From them came the ancient forms of monkeys - parapithecus, which led an arboreal lifestyle and ate plants and insects. Their distant descendants - living today gibbons, orangutans and extinct small tree monkeys - dryopithecus. Driopithecus gave rise to three developmental lines that led to chimpanzee, gorilla, as well as extinct australopithecus. From the Australopithecines at the end of the Neogene originated a reasonable person.
Archaea or Archean eon - one of the four main periods in the history of the Earth, lasted from 4.0 to 2.5 billion years ago. At this time, an oxygen atmosphere did not yet exist on Earth, but the first anaerobic bacteria appeared, which formed many of the currently existing deposits of minerals: sulfur, graphite, iron and nickel.
Eoarcheus
The first period of the Archean era lasted approximately 400 million years. This period is characterized by intense meteor showers, the formation of volcanic craters and the earth's crust. The active formation of the hydrosphere begins, salt reservoirs with hot water isolated from each other appear. The atmosphere is dominated by carbon dioxide, the air temperature reaches 120 ° C. The first living organisms appear - cyanobacteria, which begin to produce oxygen through photosynthesis. The formation of the hypothetical Vaalbara, the main earthly continent, takes place.
Paleoarchean
The next period of the Archean era spans 400 million years. The earth's magnetic field is enhanced by increasing the hardness of the earth's core. This has a beneficial effect on the living conditions and development of the simplest microorganisms. The day lasts about 15 hours. The formation of the world ocean is taking place. Changes in underwater ridges lead to a slow increase in water volume and a decrease in the amount of carbon dioxide in the atmosphere. The formation of the first earthly continent continues. Mountain ranges do not yet exist. Instead, active volcanoes rise above the ground.
Mesoarchean
The third period of the Archean era lasted 400 million years. At this time, the main continent is split into 2 parts. As a result of a sharp cooling of the planet, in which constant volcanic processes are to blame, the Pongol glacial formation is formed. During this period, the number of cyanobacteria begins to actively grow. Chemolithotrophic organisms develop, which do not need oxygen and sunlight. Vaalbar is fully formed. Its size is approximately equal to the size of modern Madagascar. The formation of the Ur continent begins. Large islands are slowly beginning to form from volcanoes. The atmosphere, as before, is dominated by carbon dioxide. The air temperature remains high.
Neoarchean
The last period of the Archean era ended 2.5 billion years ago. At this stage, the formation of the earth's crust is completed, the level of oxygen in the atmosphere increases. The mainland of Ur becomes the foundation of Kenorland. Most of the planet is occupied by volcanoes. Their vigorous activity leads to increased formation of minerals. Gold, silver, granites, diorites and other equally important natural resources were formed during the neoarchean period. In the last centuries of the Archean era, the first multicellular organisms appeared, which were later divided into terrestrial and marine life. In bacteria, the development of the sexual reproduction process begins. Haploid microorganisms have one chromosome set. They constantly adapt to changes in their habitat, but at the same time they do not appear other properties. The sexual process made it possible to adapt to life with changes in the set of chromosomes. This made it possible for the further evolution of living organisms.
Flora and fauna of Archea
The flora of this era cannot boast of diversity. The only plant species is unicellular filamentous algae - spheromorphid - the habitat of bacteria. When these algae form in a colony, they can be seen without special instruments. They can go free floating or attach to the surface of something. In the future, algae will form a new form of life - lichens.
During the Archean era, the first prokaryotes appeared - unicellular organisms without a nucleus. Through photosynthesis, prokaryotes produce oxygen and create favorable conditions for the emergence of new life forms. Prokaryotes are divided into two domains - bacteria and archaea.
It has now been established that archaea have features that distinguish them from other living organisms. Therefore, the classification that combines them with bacteria in one group is considered outdated. Outwardly, archaea are similar to bacteria, but some have unusual shapes. These organisms can absorb both sunlight and carbon. They can exist in the most unsuitable conditions for life. One of the archaea species is food for marine life. Several species have been found in the human intestine. They take part in the digestion processes. Other types are used for cleaning sewage ditches and ditches.
There is an unconfirmed theory that during the Archean era, the emergence and development of eukaryotes took place - microorganisms of the fungal kingdom, similar to yeasts.
The fact that life on earth originated in the Archean era is evidenced by the found fossilized stromalites - waste products of cyanobacteria. The first stromatolites were found in Canada, Siberia, Australia and Africa. Scientists have proven that it was bacteria that had a huge impact on the formation of crystals of aragonite, which is found in shells of mollusks and is part of corals. Thanks to cyanobacteria, deposits of carbonate and siliceous formations arose. Colonies of ancient bacteria are like mold. They were located in the area of \u200b\u200bvolcanoes, and at the bottom of lakes, and in coastal areas.
Archean climate
Scientists have not yet managed to learn anything about the climatic zones of this period. The existence of zones of different climates in the Archean era can be judged by ancient glacial deposits - tillites. Remnants of glaciers are found today in America, Africa, Siberia. It is not yet possible to determine their true size. Most likely, glacial deposits covered only mountain peaks, because vast continents were not yet formed during the Archean era. The existence of a warm climate in some zones of the planet is indicated by the development of flora in the oceans.
Archean hydrosphere and atmosphere
In the early period, there was little water on earth. The water temperature during the Archean era reached 90 ° C. This indicates the saturation of the atmosphere with carbon dioxide. There was very little nitrogen in it, there was almost no oxygen in the early stages, the rest of the gases are quickly destroyed under the influence of sunlight. The temperature of the atmosphere reaches 120 degrees. If nitrogen predominated in the atmosphere, then the temperature would not be lower than 140 degrees.
In the later period, after the formation of the world's oceans, the level of carbon dioxide began to decrease markedly. The temperature of the water and air also dropped. And the amount of oxygen increased. Thus, the planet gradually became habitable for various organisms.
Archean minerals
It is in the Archean era that the greatest formation of minerals occurs. This is facilitated by the active activity of volcanoes. Colossal deposits of iron, gold, uranium and manganese ores, aluminum, lead and zinc, copper, nickel and cobalt ores were founded by this era of the life of the earth. On the territory of the Russian Federation, Archean deposits were found in the Urals and Siberia.