The geological period. Neogene period. Triassic. Jurassic period

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 allocate geological periods of the Earth.

general information

The geological periods of the Earth (the table is shown below) represent a sequence of events that occurred during the development of the planet from the moment of the formation of the Earth's crust on it. With the passage of time, various processes occur on the surface, such as the emergence and destruction of relief forms, the submersion of land areas under water and their raising, glaciation, and the appearance and disappearance of various species of plants and animals, etc. Our planet bears clear traces Their education. Scientists claim that they are able to fix them with mathematical precision in different rock layers.

The main groups of deposits

Geologists, trying to restore the history of the planet, study the rock layers. It is accepted to divide these sediments into five main groups, distinguishing the following geological epochs of the Earth: ancient (Archean), early (Proterozoic), ancient (Paleozoic), middle (Mesozoic) and new (Cenozoic). It is believed that the border between them passes through the largest evolutionary phenomena that have occurred on our planet. The last three eras, in turn, are divided into periods, since in these sediments the remains of plants and animals are most vividly preserved. Each stage is characterized by events that have had a decisive influence on today's relief of the Earth.

The most ancient stage

The Archean era of the Earth was distinguished by rather turbulent volcanic processes, as a result of which magmatic granite rocks - the basis for the formation of continental plates - appeared on the surface of the planet. At that time there were only microorganisms that could do without oxygen. It is assumed that the deposits of the Archaean era cover the individual continental areas with an almost unbroken shield, they contain a lot of iron, silver, platinum, gold and other metals.

Early stage

The Proterozoic era is also characterized by high volcanic activity. During this period, mountain massifs of the so-called Baikal folding were formed. Up to now, they have not been practically preserved, today they represent only some insignificant uplifts on the plains. In this period, the Earth inhabited the simplest microorganisms and blue-green algae, the first multicellular ones appeared. The Proterozoic layer of rocks is rich in minerals: mica, non-ferrous metal ores and iron ores.

The Ancient Stage

The first period of the Paleozoic era was marked by the formation of mountain ridges of Caledonian folding. This led to a significant reduction in marine basins, as well as the emergence of huge land areas. Until now, there are some ranges of the period: in the Urals, in Arabia, South-East China and Central Europe. All these mountains are "worn out" and low. The second half of the Paleozoic is also characterized by mountain-forming processes. Here the ridges of Hercynian folding were formed. This era was more powerful, there were vast mountain ranges in the territories of the Urals and Western Siberia, Manchuria and Mongolia, Central Europe, as well as Australia and North America. Today they are represented by very low block massifs. Animals of the Paleozoic era are reptiles and amphibians, the seas and oceans are inhabited by fish. Among the plant world, algae prevailed. The Paleozoic era (the Carboniferous period) is characterized by large deposits of coal and oil, which arose precisely in this era.

Middle stage

The beginning of the Mesozoic era is characterized by a period of relative tranquility and the gradual destruction of the mountain systems created earlier, the submersion of plains territories (part of Western Siberia). The second half of this period was marked by the formation of ridges of Mesozoic folding. There were very extensive mountainous countries, which today have the same face. For example, the mountains of Eastern Siberia, the Cordillera, some areas of Indochina and Tibet. The earth was densely covered with lush vegetation, which gradually died off and rotted. Thanks to the hot and humid climate, active formation of peat bogs and marshes took place. This was the era of giant dinosaurs - dinosaurs. The inhabitants of the Mesozoic era (herbivorous and carnivorous animals) spread throughout the entire planet. At the same time, the first mammals also appear.

New stage

The Cenozoic era, which replaced the middle stage, continues to this day. The beginning of this period is marked by an increase in the activity of the internal forces of the planet, which led to a general rise of huge areas of land. This era is characterized by the emergence of mountain ranges of Alpine folding within the Alpine-Himalayan belt. During this period, the Eurasian continent acquired modern outlines. In addition, there was a significant rejuvenation of the ancient massifs of the Urals, Tien Shan, Appalachians and Altai. Sharply changed the climate on Earth, the periods of powerful ice coverings began. The movements of glacial masses altered the relief of the continents of the Northern Hemisphere. As a result, hilly plains with a huge number of lakes were formed. Animals of the Cenozoic era are mammals, reptiles and amphibians, many representatives of the initial periods have reached to this day, others have died out (mammoths, woolly rhinoceroses, saber-toothed tigers, cave bears and others) for one reason or another.

What is a geological period?

The geological stage as a unit of the geochronological scale of our planet is usually divided into periods. Let's see what this term says in the encyclopedia. The period (geological) is a large interval of geological time, during which rocks were formed. In turn, it is subdivided into smaller units, which are usually called epochs.

The first stages (Archean and Proterozoic) in connection with the complete absence or insignificant amount of animal and vegetable deposits in them are not divisible into additional areas. The Paleozoic era includes the Cambrian, Ordovician, Silurian, Devonian, Carbonian and Permian periods. This stage is characterized by the largest number of sub-intervals, the rest are limited to only three. The Mesozoic era includes the Triassic, Jurassic and Cretaceous stages. The Cenozoic era, the periods of which have been most studied, is represented by the Paleogene, the Neogene and the Quaternary sub-interval. Let us consider some of them in more detail.

Triassic

The Triassic period is 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 the renewal of marine and terrestrial fauna. At the same time, a few representatives of the Paleozoic continue to exist, such as the spiriferidae, tabuli, some lamellarbranch, etc. Among the invertebrates, ammonites are very numerous, giving many new forms important for stratigraphy. Among the corals, six-rayed forms prevail, of brachiopods - terrebratulids and rhinchonelids, in the group of echinoderms - sea urchins. Vertebrate animals are mainly represented by reptiles - large lizhorotazovymi dinosaurs. Tecodons are widely distributed - terrestrial fast-moving reptiles. In addition, in the Triassic period, the first large inhabitants of the aquatic environment appear - ichthyosaurs and plesiosaurs, but they reach their heyday only in the Jurassic period. Also at this time, the first mammals appeared, which were represented by small forms.

Flora in the Triassic period (geological) loses elements of the Paleozoic and acquires exclusively Mesozoic composition. Here fern rock breeds predominate, saggy, coniferous and ginkgo. Climatic conditions are characterized by significant warming. This leads to the drying out of many inner seas, and in the remaining ones the salinity level essentially increases. In addition, the areas of inland water bodies are very reduced, resulting in the development of desert landscapes. For example, the Taurian formation of the Crimean peninsula is referred to this period.

Yura

The Jurassic period got its name due to the Jurassic mountains in Western Europe. It forms the middle part of the Mesozoic and most closely reflects the main features of the development of organic matter of this era. In turn, it is customary to divide it into three divisions: lower, middle and upper.

The animal world of this period is represented by widely spread invertebrates - cephalopods (ammonites represented by numerous species and genera). They are very different from the representatives of the Triassic according to the sculpture and the character of the shells. In addition, in the Jurassic period, another group of mollusks, belemnites, is flourishing. At this time, significant development is achieved by six-beam reef-forming corals, sea sponges, lilies and hedgehogs, as well as numerous lamellarbranch. But the species of the Paleozoic brachiopod completely disappear. The marine fauna of vertebrate species differs significantly from the Triassic, it reaches a great variety. In the Jurassic period, fish are widely developed, as well as aquatic reptiles - ichthyosaurs and plesiosaurs. At this time, there is a transition from land and adaptation to the marine environment of crocodiles and turtles. A great variety is achieved by various species of terrestrial vertebrates - reptiles. Among them, dinosaurs come to their flowering, which are represented by herbivorous, carnivorous and other forms. Most of them reach 23 meters in length, for example, diplodok. In sediments of this period, a new species of reptiles - flying lizards, which are called "pterodactyls". At the same time, the first birds appear. The flora of the Jurassic is flourishing: gymnosperms, ginkgoers, cicadas, conifers (araucaria), bennettites, cadavers and, of course, ferns, horsetails and plaques.

Neogene

Neogene period is the second period of the Cenozoic era. It began 25 million years ago and ended 1.8 million years ago. At this time, there were significant changes in the composition of the fauna. There is a wide variety of gastropods and bivalves, corals, foraminifera and coccolithophorids. Amphibians, sea turtles and bony fishes have developed extensively. In the Neogene period of great diversity, terrestrial vertebral forms also reach. For example, there were rapidly progressive gipparionovye species: gippariony, horses, rhinoceroses, antelopes, camels, proboscis, deer, hippos, giraffes, rodents, saber-toothed tigers, hyenas, anthropoid apes and others.

Under the influence of various factors at this time, the organic world is rapidly evolving: forest-steppe, taiga, mountain and plain steppes arise. In the tropical regions - savannas and wet forests. Climatic conditions are close to modern.

Geology as a science

Geological periods of the Earth are studied by science - geology. It appeared relatively recently - at the beginning of the 20th century. However, despite her youth, she was able to shed light on many controversial questions about the formation of our planet, as well as the origin of the creatures inhabiting it. In this science there are few hypotheses, mainly only the results of observations and facts are used. There is no doubt that the traces of the planet's development in the Earth's layers will in any case give a more accurate picture of the past than any compiled book. However, to be able to read these facts and not correctly understand them, so even in this exact science, from time to time there may be erroneous interpretations of certain events. Where there are traces of fire, it can be confidently asserted that the fire was; And where there are traces of water, with the same certainty can be argued that the water was and so on. And yet mistakes also happen. In order not to be unfounded, let us consider one such example.

"Frozen ornaments on glasses"

In 1973, the magazine "Knowledge is Power" published an article by the famous biologist AA Lyubimtsev "Frosty patterns on the glasses." In it the author draws readers' attention to the striking similarity of ice patterns with plant structures. As an experiment, he photographed the pattern on the glass and showed the photograph to a familiar botanist. And without slowing down, he recognized the fossilized trail of a thistle in the picture. From the standpoint of chemistry, these patterns arise from the gas phase crystallization of water vapor. However, something similar happens in the preparation of pyrolytic graphite by pyrolysis of methane diluted with hydrogen. Thus, it was found that, aside from this stream, dendritic forms are formed, which are very similar to plant remains. This is explained by the fact that there are general laws that govern the formation of forms in inorganic matter and living nature.

For a long time geologists dated each geological period, relying on traces of plant and animal forms found in coal deposits. And just a few years ago there were statements of some scientists that such a method is incorrect and that all the fossils found are nothing but a by-product of the formation of the Earth's layers. No doubt, you can not all measure the same, but you need to more carefully approach dating issues.

Was there a worldwide glaciation?

Let's consider one more categorical statement of scientists, and not only geologists. All of us, beginning with the school, were inspired by the worldwide glaciation that covered our planet, as a result of which many species of animals died out: mammoths, woolly rhinoceroses and many others. And the modern rising generation is brought up on the quadrology "Ice Age". Scientists unanimously assert that geology is an exact science that does not allow theories, but uses only proven facts. However, this is not the case. Here, as in many fields of science (history, archeology, and others), one can observe the stiffness of theories and the unshakable authority. For example, since the end of the nineteenth century, on the sidelines of science, heated debates have been held about whether there was a glaciation or not. In the middle of the twentieth century, the famous scientist-geologist IG Pidoplichko published a four-volume work "On the Glacial Period". In this work the author stages by stages the insolvency of the version of the global glaciation. He relies not on the works of other scientists, but on personally conducted geological excavations (some of which he conducted as a Red Army fighter, participating in battles against German invaders) throughout the Soviet Union and Western Europe. He argues that the glacier could not cover the entire continent, but only had a local character, and that it did not cause the extinction of many species of animals, and quite other factors are the catastrophic events that led to the displacement of the poles (The Sensational History of the Earth, A Sklyarov); And the economic activity of the person himself.

Mysticism, or Why do scientists not notice the obvious

Despite the irrefutable evidence given by Pidoplichko, scientists are slow to abandon the accepted version of the glaciation. And then it's even more interesting. The author's works were published in the early 1950s, but with the death of Stalin all copies of the four-volume book were removed from the libraries and universities of the country, preserved only in the library's storage rooms, and it is not very easy to get them from there. In Soviet times, everyone who wanted to take this book in the library was registered by the secret services. And even today, there are certain problems in obtaining this print edition. However, thanks to the Internet, anyone can get acquainted with the works of the author, who examines in detail the periods of the geological history of the planet, explains the origin of those or other traces.

Geology is an exact science?

It is believed that geology is an exceptionally experienced science that deduces conclusions only from what it sees. If the case is doubtful, it does not approve anything, expresses an opinion that allows discussion, and postpones the final decision until unambiguous observations are received. However, as practice shows, the exact sciences are also mistaken (for example, physics or mathematics). And nevertheless mistakes are not a catastrophe if they are accepted and corrected in time. Often they are not global in nature, but have a local meaning, you just need to have the courage to take the obvious, draw the right conclusions and move on to meet new discoveries. Modern scientists show the fundamentally opposite behavior, because most of the science luminaries have received titles, awards and recognition for their work, and today they do not want to part with them. And this behavior is seen not only in geology, but also in other areas of activity. Only strong people are not afraid to admit their mistakes, they are glad to be able to develop further, because the discovery of a mistake is not a disaster, but, on the contrary, a new opportunity.