Geochronological scale of era periods of an era. Geochronological scale

Geol. Scale time, showing the sequence and subordination of the stages of development crust and organic the world of the Earth (eons, eras, periods, eras, centuries). The sequence of deposits is reflected in the so-called. strapgraphic. scale, units to the swarm ... ... Biological encyclopedic Dictionary

- (a. geological dating, geochronological scale; n. geologische Zeitrechnung; f. echelle geochronologique; and. escala geocronologica) sequential. a number of geochronological. equivalents of common stratigraphic. subdivisions and their taxonomy. ... ... Geological encyclopedia

geochronological scale- - Topics oil and gas industry EN geologic time scale ...

See in Art. Geochronology ... Great Soviet Encyclopedia

Phanerozoic geochronological scale- (duration 570 million years) Eras and their duration Periods Beginning of periods, million years ago Length of periods, million years Development of life Cenozoic (67 million years) Anthropogenic Development of mankind. Neogene The appearance of man ... ... The beginnings of modern natural science

geochronological scale- The scale of geological time, showing the sequence and subordination of the main stages of the geological history of the Earth and the development of life on it. [Dictionary of geological terms and concepts. Tomsk State University] Topics geology ... Technical translator's guide

The scale of the relative geol. time, showing the sequence and subordination of the main stages of geol. the history of the Earth and the development of life on it. It is the result of analysis and synthesis of all data on the stratigraphic scale and, accordingly ... ... Geological encyclopedia

Sokh, Doell, Dalrymple, 1968, based on inversions magnetic field Earth, which has occurred many times in geol. past. Developed for the last 4.5 million years of the Cenozoic. The main units of the Sh. Of the item are epochs (with a duration of about 1 1.5 million le ... Geological encyclopedia

geochronological scale- geochronological scale geological dating, geochronological scale geologische Zeitrechnung the last series of geochronological equivalents of the outlying stratigraphic parallels and taxonomical conditions. The first geochronological scale for ... ... Girnichy encyclopedic vocabulary

Age of some regions on the Moon: 1 Age of craters (a Nectarian, b Imbrian, c Eratosthenic, d Copernicus) 2 Age of the seas (a denectarian, b nectar, c early ... Wikipedia

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Geochronological table

This is a list of time divisions or intervals, in order of their hierarchy.

Chronometric scale

This is a scale of isotopic age, based on the radioactive decay of elements, from the moment of their formation to the present day.
Akron is a time span of 2 billion years.
Aeon is a span of 1 billion years.
The era is hundreds of millions of years.
Period - tens of millions of years
The epoch is tens of millions of years.

Stratigraphic scale

This is the rock scale. Represents a complete perfect cut of the Earth's crust

See also: Evolution of the Earth's Geographic Shell, Geochronological Scale (original article).

The evolution of living things can only be understood in the context of geological time.

Geochronological (stratigraphic) time scale - it is a scale of relative geological time, built on the basis of the stages of the formation of the earth's crust and life on the planet, determined by paleontology and historical geology. It is a sequence of stratigraphic elements in the order of their formation, in the form of a complete composite ideal section of all terrestrial deposits without gaps and overlaps, and is a standard for the correlation of any stratigraphic units. The boundaries between stratigraphic elements are drawn from events of significant evolutionary or geological change. The doctrine of the chronological sequence of formation and age of rocks that compose the earth's crust is called geochronology .

Distinguish between relative and absolute geochronology.

The task relative geochronology is to determine the relative age of rocks: determining which deposits found in the earth's crust are older and which are younger. There are several methods for determining the relative age of rocks.

The first method is - stratigraphic... He proceeds from a completely unclear and logical idea that each layer of sedimentary rocks was formed before the layer that overlaps it.

The second method is - paleontological... It allows you to establish the relative age of rocks and to compare them in geological sections related to different areas or regions. Establishment is made by the nature of various organic remains found in the strata (fossilized sea shells, animal bones, leaf prints, etc.).

The task absolute geochronology is to determine the true duration of individual periods and epochs in the life of the Earth, as well as its geological age as a whole.

The geochronological age of rocks is determined by such units of measurement as era, period, epoch and century.

Era - the largest stage in the history of the development of the Earth, in which a group of deposits was formed. There are five eras (starting with the older ones): Archean, Proterozoic, Paleozoic, Mesozoic and Cenozoic.

Each era spans several periods. The period corresponds to the time of formation of the rock system. The periods are subdivided into several epochs, which correspond to the divisions of the rocks. Epochs are subdivided into ages, which correspond to tiers as a set of rocks formed in a particular century.

Archean(era of primary life) and proterozoic(era of ancient life) era the most distant from us in time (about 1.5 billion years). At this time, the most ancient rocks were formed, which make up the hard foundation of the earth's crust. The rocks of the Archean era bear only traces of primitive organic forms, testifying to the origin of life on Earth at this time. The Proterozoic era coincides in time with the beginning of the development of various algae, bacteria and invertebrates on Earth.

Palaeozoic(the era of ancient life) - a period of time removed from us by about 600 million years and lasted about 350 million years. This era and related breeds have been studied in more detail. The Paleozoic era is characterized by the exuberant flowering of organic life in the seas and oceans and its emergence on land. On land, large amphibians become dominant and at the end of the era - the first reptiles. In the Carboniferous period of the era, tree ferns, horsetails, etc. are lush development.

The Paleozoic era is subdivided into six periods (starting with the older ones): Cambrian (Cm), Ordovician (O), Silurian (S), Devonian (D), Carboniferous (C), and Permian (P).

Mesozoic era(the era of average life) with a duration of 185 million years is the heyday of giant reptiles on land (giant dinosaurs - dinosaurs, flying pterodactyls, etc.). Vegetable world and the insect world in the Mesozoic has some features in common with our time. At this time, the first representatives of mammals and birds appeared on Earth, which developed in the next, Cenozoic era.

The Mesozoic era is subdivided into three periods: Triassic (T), Jurassic (J) and Cretaceous (Cr).

Cenozoic era(era of new life) - the youngest (about 40 ... 50 million years BC), which replaced Mesozoic era... Life at this time takes on forms closer to our time.

The Cenozoic era is subdivided into three periods: Paleogene (Pg), Neogene (N), and Anthropogenic (Ap), or Quaternary (Q). Quaternary period - the last period of development organic world, during which a person appeared.

Rocks up to the Quaternary age are called indigenous, and continental Quaternary - integumentary... Within the bedrock, in the general case, the older rocks are stronger than the younger ones, and the quaternary cover formations have a lower strength than the bedrock. But there is no direct connection between the age of rocks and their strength, and sometimes young rocks are more durable than ancient ones.

As a result of studying the age, composition, conditions of occurrence and distribution of rocks, geological maps are compiled, which show the outcrops of bedrocks to the surface of the earth. Quaternary deposits are generally not shown on geological maps; special maps of Quaternary (cover) deposits are made for them. This is done for the reason that the rocks, up to the Quaternary, in the overwhelming majority of cases are of marine origin and are distinguished by a well-defined regularity of the structure of layers, both in plan and in depth. Quaternary rocks, on the contrary, in most cases are of continental origin (formed within the land). These rocks are characterized by an extremely variable composition, and the boundaries of their distribution are usually determined by the existing relief of the area.

The accumulated materials on the geological structure of the earth's crust and the development of life made it possible to break it geological history for six eras and compose a scale of geological time - a geochronological scale.

Each era is divided into periods, a period into eras, epochs into centuries.

Archean era - the era of the beginning of life

Proterozoic era - the era of primary life

Riphean - era of early life

Paleozoic era of ancient life

Mesozoic - era of middle life

Cenozoic - the era of modern life.

The eras are united into two eons by Cryptose and Phanerozoa.

Croptose unites the Archean, Proterozoic and Riphean eras. This eon accounts for almost 4 billion years, or 5/6 of the entire geological chronology.

This is the time of the origin of life, the emergence of primitive unicellular organisms. The skeletal fauna is completely absent.

They are characterized by active tectonic activity, as a result of which the geological structure of the earth's crust was formed, the appearance of water and the first simple forms of life, the accumulation of the first thick strata of sedimentary rocks. First, the platforms of the northern hemisphere and the Australian platform were formed, later the Hindustan, South American, African and Antarctic. At the same time, the first geosynclines (folded mountains) were formed.

Geological formations of these eras are represented by igneous, ancient sedimentary and metamorphic rocks: crystalline schists, limestones, marbles, etc. In a non-weathered state, these rocks are a good foundation and good building materials. They form the crystalline basement of the Russian, West Siberian and other plains, come to the surface in our country south of Voronezh, in Karelia, the Murmansk region, in Eastern Siberia, in the Urals, in Central Asia and in Altai.

Other eras - the Pleozoic, Mesozoic and Cenozoic - are combined into the Phanerozoic (approximately 570 Ma). The Faenerozoic is the most important stage in the geological history of the Earth, which is characterized by the emergence and widespread development of skeletal organisms, the flourishing of the organic world and the appearance of man.

Palaeozoic–Pz began about 525-570 million years ago and lasted for about 340 million years. The Paleozoic era is divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. If necessary, changes were introduced to the standard stratigraphic scale reflecting regional specifics. For example, in Europe, the Carboniferous period stands out, and in the United States, two correspond to it - the Mississippi and the Pennsylvania.

The Paleozoic era is mostly very warm and humid subtropical climate, which led to the formation of many rocks of organogenic origin. During this period, there were two main phases of mountain building, accompanied by intense crushing of rocks. The first, Caledonian phase took place on the territory of Scotland, Western Scandinavia, Greenland, on the territory of Russia it is the Transbaikalia region. During the second, Hercynian phase, the Ural Mountains, Tien Shan, Altai and others were formed. In the era of rock formation, the tropical climate was replaced by a sharp cooling, and in the era of the Hercynian phase, glaciation even occurred.

In the Paleozoic era, limestones, marls, dolomites were formed in the seas, and clays, sands and sandstones on the continents. In the last periods of the Paleozoic - Carboniferous and Permian - powerful deposits of coal, limestones, sandstones, shales, as well as chemical sedimentary rocks - gypsum, anhydrite, rock salt were formed. The rocks formed during this era contain many remains of fauna and flora. The forms were primitive and were very far from modern ones, these are spore plants and invertebrates, and subsequently extinct vertebrates.

Most of the rocks of the Paleozoic era can serve as a reliable foundation and be used as building materials.

Mesozoic era Mz (the era of middle life) began 190 million years ago and had a duration of about 125 million years, is divided into three periods - Triassic, Jurassic and Cretaceous. The era is distinguished by a relatively warm monotonous climate and tectonic calm. Only in the Jurassic period did the Cimmerian phase of mountain building take place, as a result of which the formation of the Caucasian and Crimean mountains began. At the same time, a continental climatic situation is observed, in which coals and clays were formed.

During the Mesozoic, marine and continental deposits were equally distributed. Within the Russian plain, thick deposits of chalk, limestone, and clay were formed. The possibilities of using rocks of the Mesozoic era for construction purposes are the same as in the Paleozoic period.

During this era, reptiles were very large in size. Fauna and flora were of a transitional nature - from ancient forms of the organic world to modern ones.

Cenozoic eraKz(the era of new life) began 65 million years ago. Vegetable and animal world approaches modern forms, a man appears. The era is divided into three periods - Paleogene, Neogene and Quaternary. The first two periods are usually combined into one - tertiary. The Quaternary period takes only 1 million years and has been studied in most detail. It was at the beginning of the Quaternary that man appeared.

The Cenozoic era is distinguished by different, sharply different climatic conditions. During the Paleogene period, the climate was warm, almost tropical; during the Neogene period, a cooling is observed, which in the Quaternary period passed into the Ice Age with periodic glaciations. Glaciation has captured a huge territory of northern Europe and Asia.

In the Cenozoic era, the so-called alpine folding, the formation of which began in the Jurassic period, was very intensely manifested. In the Tertiary period, the formation of the Caucasian and Crimean mountains ended. At the same time, ridges appeared North Africa, Alps, Carpathians, Pamir Mountains, Tien Shan, Himalayas, Kuril Islands, Sakhalin Kamchatka. The Alpine mountain building phase is not over yet.

In the Tertiary period, rocks of marine and continental origin were formed. Marine tertiary deposits - clays, shell limestones, etc. are located on the Black Sea coast and in other places. Continental Tertiary deposits are ubiquitous.

The overwhelming majority of rocks of the Quaternary period are continental deposits - loose rocks and rocks of organogenic origin. They are usually called Quaternary rocks or sediments, in contrast to the earlier rocks, which I call bedrock. Marine Quaternary sediments in Russia are rare - on the coast of the seas, north and east of the Caspian Sea and on the northern coast of the Black Sea. These deposits are similar in composition and properties to tertiary ones. A special group among them are sea silts.

The thickness of the Quaternary deposits ranges from several centimeters to tens and hundreds of meters. These breeds are less reliable as bases than the roots. Their properties vary within wide limits and largely depend on genetic characteristics.

The bedrock is usually represented by rocky and compacted sandy and clayey rocks, and among the Quaternary deposits, loose formations, weakly cemented and cohesive, prevail.

The geochronological scale is represented by the sequence of the Earth's history, dividing it into a system of time intervals. It reflects the relative ages of sedimentary layers based on their mutual disposition and the presence of organic residues.

History of creation

The geochronological scale was compiled and approved in 1881 at the International Geological Congress. Initially, it was a sequence of periods divided into eras. The latter were united into eras. That is, the original scale included three subdivisions. Later, a fourth, larger category was introduced - the aeon. In 2004, the International Union of Geological Sciences approved the developed by the International Commission on Stratigraphy.

In Russia, the geochronological scale, combined with the stratigraphic one, was approved at the end of the 20th century. (1992). At the same time, an even larger division was added - acrons.

Basic principles

The geochronological scale is based on the subdivision of sedimentary strata or associated igneous massifs by relative age.

Its definition relates to the tasks of geochronology. For this purpose, the methods of paleontology and stratigraphy are used.

Application

The use of the geochronological scale is determined by the fact that it links geological events in the history of the planet. In view of this, it is widely used in the sciences of the geological cycle. In addition, the stratigraphic scale is the basis for the compilation of geological maps.

In addition, the geochronological scale has a large practical significance... So, it is used in regional geological studies aimed at clarifying the tectonic features of the territory, determining the direction of prospecting and exploration of minerals, especially those associated with reservoir deposits corresponding to specific stratigraphic levels. Geological maps, created on the basis of a geochronological scale, are used in engineering and geological works, environmental studies, etc.