According to modern ideas of scientists, the geological history of our planet is 4,5-5 billion years.In the process of its development it is customary to distinguish geological periods of the earth.
geological period of the Earth (table shown below) is a sequence of events that occurred during the development of the planet since the formation of the Earth's crust on it.With the passage of time on the surface there are various processes, such as the emergence of forms of relief and destruction, immersion land areas under water and raising them, glaciation, and the appearance and disappearance of various species of plants and animals and so on. D. Our planet bears obvious tracestheir education.Scientists claim that they are able to fix their mathematical precision in the different layers of rocks.
main group deposits
Geologists, trying to reconstruct the history of the planet, studying the rock layers.It adopted these deposits divided into five major groups, highlighting the following geological eras of the Earth: Ancient (Archean), early (Proterozoic), ancient (Paleozoic), average (Mesozoic) and the new (Cenozoic).It is believed that the border between them is held by the largest evolutionary phenomena occurring on our planet.The last three eras, in turn, are divided into periods, as in these sediments is most clearly preserved remains of plants and animals.Each stage is characterized by the events that had a decisive influence on the present topography of the Earth.
Archean era is quite different from the Earth's turbulent volcanic processes, which resulted in the surface of the planet appeared igneous granite rocks - the basis for the formation of the continental plates.While there are only microorganisms that could do without the oxygen.It is assumed that the Archean era deposits cover almost whole shield certain areas of the continents, they have a lot of iron, silver, platinum, gold and other metal ores.
Proterozoic era is also characterized by high volcanic activity.During this period, formed mountains so-called Baikal folding.To this day, they almost did not survive, now represent only some insignificant raising on the plains.During this period, Earth was inhabited by simple organisms, and blue-green algae, the first multicellular.Proterozoic rock strata rich in minerals: mica, non-ferrous ores and iron ores.
first period of the Paleozoic era was marked by the formation of mountain ranges of the Caledonian orogeny.This led to a significant reduction in sea basins, as well as the emergence of huge areas of land.Have survived some ridges of the period: the Urals, Arabia, South East China and Central Europe.All these mountains are "worn out" and low.The second half of the Paleozoic as is typical of orogenic processes.There ridges formed Hercynian folding.This era was more powerful, there were vast mountains in the Urals and Western Siberia, Manchuria and Mongolia, Central Europe, as well as Australia and North America.Today they presented a very low blocky arrays.Animals of the Paleozoic era - a reptiles and amphibians, seas and oceans are inhabited by fish.Among the flora was dominated by algae.Palaeozoic (Carboniferous period) is characterized by large deposits of coal and oil, which have arisen in this era.
Home Mesozoic era is characterized by a period of relative calm and a gradual destruction of the mountain ranges created earlier diving lowland areas (part of Western Siberia).The second half of this period was marked by the formation of ridges Mesozoic folding.There is quite an extensive mountainous country, which even today have the same appearance.As an example, the mountains of Eastern Siberia, the Cordillera, some parts of Indo-China and Tibet.The ground was thickly covered with lush vegetation, which gradually die and rot.Due to hot and humid climate occurred active formation of peat bogs and marshes.This was the era of giant lizards - the dinosaurs.Inhabitants of the Mesozoic era (herbivores and carnivores) have spread throughout the world.At the same time it appears and the first mammals.
Cenozoic Era, which replaced the middle stage, lasts to this day.Beginning of the period was marked by an increase in the activity of the internal forces of the world, which led to a general raising of the huge land areas.This era is characterized by the emergence of mountain ranges within the Alpine folding in the Alpine-Himalayan belt.During this period, it gained modern outlines of the Eurasian continent.In addition, there was a significant rejuvenation of the ancient massifs of the Urals, Tien Shan and Altai mountains of Appalachia.Dramatically changed the climate on Earth, began a period of strong glaciation.Movement of the ice masses changed topography of the continents of the Northern Hemisphere.The result is a hilly plain with lots of lakes.Pets Cenozoic era - are mammals, reptiles and amphibians, many of the initial period came to our days, others become extinct (mammoths, woolly rhinoceroses, saber-toothed tigers, cave bears, etc.) for one reason or another.
What is the geological period?
Geological stage as the unit of geological time scale of our planet can be divided into periods.Let's see what is said about this term in the encyclopedia.Period (geology) - it is a large geological time interval at which the rocks were formed.In turn, it is divided into smaller units, which are called epochs.
first stage (Archean and Proterozoic) due to the complete lack or negligible amount of fat in their plant and animal nature to divide into additional sites pending.Paleozoic era includes the Cambrian, Ordovician, Silurian, Devonian, Permian and karbonsky.This stage is characterized by the highest number of sub intervals, and the rest were limited to only three.Mesozoic Era includes the Triassic, Jurassic and Cretaceous stages.Cenozoic era, periods of which the most studied is presented Paleogene, Neogene and Quaternary sub-interval.Let us consider some of them.
Triassic period - the first sub-interval of the Mesozoic era.Its duration was about 50 million years (beginning - 251-199 million years ago).It is characterized by updating the marine and terrestrial fauna.At the same time continue to exist a few representatives of the Paleozoic, such as spiriferid, tabulate, some elasmobranch and others. Among the invertebrates are numerous ammonites, which gave a lot of new forms that are important for stratigraphy.Among the six-rayed corals predominate form of brachiopods - terebratulidy rinhonelidy and in the group of echinoderms - sea urchins.Vertebrates are mainly represented by reptiles - dinosaurs Saurischia large.Widespread thecodonts - ground fast-moving reptiles.In addition, during the Triassic period, there are the first large aquatic organisms - the plesiosaurs and ichthyosaurs, but they reach its peak only in the Jurassic period.Also at this time, and the first mammals appeared, which were presented in small forms.
Flora Triassic (geological) loses the elements of the Paleozoic and Mesozoic only takes part.It is dominated by rock fern plants sagovoobraznye, conifers and Ginkgoales.The climatic conditions are characterized by a significant warming.This leads to the drying up of many of the inland seas, and in the remaining substantially increases the level of salinity.In addition, a very reduced area of inland water bodies, resulting in developing desert landscapes.For example, in this period include Tauride formation of the Crimean peninsula.
Jurassic got its name from the Jura mountains in western Europe.He is the middle part of the Mesozoic and the most densely reflects the main features of this organic era.In turn, it can be divided into three sections: the lower, middle and upper.
The fauna of this period is represented by widely spreading the invertebrates - cephalopods (ammonites, represented by numerous species and genera).They sculpture and nature shells are very different from the representatives of the Triassic.In addition, in the Jurassic period is flourishing another group of molluscs - belemnite.At that time, significant development achieved a six-reef-building corals, marine sponges, lilies and urchins, as well as numerous elasmobranch.But completely disappear Paleozoic brachiopod species.The marine fauna vertebrate species differs significantly from the Triassic, it reaches a huge variety.The Jurassic widespread fish and aquatic reptiles - ichthyosaurs and plesiosaurs.At this time there is a transition from land and adaptation to the marine environment, crocodiles and turtles.A huge variety of different types of reach of terrestrial vertebrates - reptiles.Among them come to their flowering dinosaurs, which are represented by herbivores, predatory and other forms.Most of them reaches 23 meters in length, such as Diplodocus.The deposits of this period found a new species of reptiles - the flying lizards, which are called "pterodactyls".At the same time there and the first birds.Jurassic flora reaches luxuriant growth: gymnosperms, Ginkgoales, cycads, conifers (Araucaria), bennettites, sagovnikovye and, of course, ferns, horsetails and club mosses.
Neogene Neogene period - the second period of the Cenozoic era.It began 25 million years ago and ended 1.8 million years ago.At this time, there have been significant changes in fauna.There is a great variety of gastropods and bivalves, corals, and foraminifera coccolithophorids.Widely developed amphibians, turtles and bony fish.The Neogene reach a wide variety of shapes and terrestrial vertebrates.For example, there Rapidly hipparion types: hipparions, horses, rhinoceroses, antelopes, camels, Khobotova, deer, hippos, giraffes, rodents, saber-toothed tigers, hyenas, and other great apes.
Under the influence of various factors at this time of rapidly evolving organic world: there steppe, taiga, mountain and plain steppe.In tropical areas - savanna and rainforest.The climatic conditions are close to modern.
geology as a science
geological period of the Earth is studying science - geology.It appeared relatively recently - in the early 20th century.However, despite her youth, she resin shed light on many contentious issues on the formation of our planet, as well as the origin of the creatures that inhabit it.In this little science hypotheses, mainly used only the results of observations and facts.No doubt that is stored in the layers of the earth traces the development of the world in any case give a more accurate picture of the past, than any book penned.However, to be able to read these facts and understand them correctly is not given to everyone, so even in this exact science, from time to time there may be erroneous interpretations of certain events.Where there are signs of fire, we can confidently assert that the fire was;and where there are traces of water, with the same confidence can be argued that the water was, and so on.Nevertheless errors also occur.Not to be unfounded, we look at one such example.
«Frosty patterns on the glass»
In 1973 the magazine "Knowledge - force" published an article by the famous biologist A. Lyubimtseva "Frosty patterns on the glass."The author draws the reader's attention to the striking similarity of ice patterns with plant structures.As an experiment, he photographed pattern on glass and showed the photo to my friend the botanist.And that without delay recognized the picture fossilized footprint thistle.From the standpoint of the chemistry of these patterns occur due to crystallization of water vapor gas phase.However, something similar is happening in the preparation of pyrolytic graphite by pyrolysis of methane diluted with hydrogen.Thus, it was found that apart from this flux generated dendritic forms that are very similar to plant residues.The reason is that there are general laws that govern the formation of inorganic forms of matter and nature.
For a long time, geologists have dated every geological period, based on traces of plant and animal forms, found in coal deposits.And only a few years ago there were claims by some scientists that this method is incorrect and that all the fossils - that other, as a byproduct of the formation of Earth's layers.No doubt, it is impossible to measure all the same, but we need a more careful approach to the issues of dating.
And whether global glaciation?
Consider another categorical statement of scientists, and not only to geologists.All of us, from school, inspired the World glaciation that covered the planet, resulting in many species of animals become extinct: mammoths, woolly rhinos and many others.And the modern younger generation brought up on Quadrilogy "Ice Age."Scientists in one voice say that the geology - an exact science, not allowing the theories and uses only proven facts.However, it is not so.Here, as in many areas of science (history, archeology, and others), you can watch the theories rigidity and firmness of authority.For example, since the late nineteenth century, in the margins of science it is heated debate about whether or not icing.In the middle of the twentieth century, the famous scientist and geologist IG Pidoplichko four-volume work was published "On the ice age."In this paper, the author shows stages of insolvency version of the World glaciation.It is not based on the works of other scholars, and he personally conducted geological excavations (some of which he spent, as the Red Army, taking part in battles against the German invaders) throughout the territory of the Soviet Union and Western Europe.He argues that the glacier could not cover the entire continent, and only wore a local character, and that he had not caused the extinction of many animal species, and most other factors - this catastrophic event that led to a shift of the poles ("Sensational history of the Earth," A. Sklyarov);and economic activity of the person.
Mystery or Why scientists do not notice the obvious
Despite overwhelming evidence given Pidoplichko, scientists are in no hurry to abandon the adopted version of glaciation.And then even more interesting.The artworks were published in the early 50s, but with the death of Stalin, all instances of four volumes were withdrawn from libraries and universities of the country, preserved only in the vaults of the libraries, and get them out rather than just.In Soviet times, everyone take this book in the library were taken on account of the secret services.And even today there are some problems in obtaining this publication.However, thanks to the Internet, everyone can get acquainted with the works of the author, which examines in detail the periods of geological history of the planet, explains the origin of certain tracks.
Geology - an exact science?
believed that geology - a science purely experimental, which is concluded only from what he sees.If the case is questionable, it does not assert anything, expresses the opinion that admits discussion and postpones a final decision until such time until you obtain a unique observation.However, as practice shows, the sciences, too, make mistakes (eg, physics or mathematics).Yet mistakes are not a disaster if they take time and correct.Often they are not global, but have local significance only need to have the courage to accept the obvious, draw the right conclusions and move on to meet new discoveries.Modern scientists have shown dramatically the opposite behavior, because most of the luminaries of science in his time received titles, awards and recognition for their work, and now they do not want to part with them.