The era to which the Quaternary period belongs. Cenozoic Ice Age. Aromorphoses of the Cenozoic era

The most recent era on the Earth's timeline is the Cenozoic era - an era that literally means "New Life". This is an era that began 65 million years ago and continues to the present day. This era is often referred to by paleontologists as the “Age of Mammals.” However, this is not entirely wrong because mammals were not the only class of animals that flourished during this era. Birds, insects and flowering plants also flourished and diversified during this time.

This era can be divided into three distinct periods:

Paleogene period

Neogene period

Quaternary period.

In turn, these three periods can be divided into seven eras:

Paleocene

Eocene

Oligocene

Miocene

Pliocene

Pleistocene

Holocene

This era is divided into as many subgroups to help scientists study this short period.

The first period of the Cenozoic era was the Paleogene period, and it began approximately 66 million years ago and ended 23 million years ago. During this time, the Earth began to recover after a global cataclysm that destroyed almost all life, it is called K-T extinction. This was also the period when the continents began to take on their modern shape. Small mammals began to develop in the jungle, they greatly increased in size. This period includes the Paleocene, Eocene and Oligocene.

The Paleocene Epoch lasted about 10 million years (began 66 million years and ended 56 million years). It was during this period that the Earth truly tried to recover. This was also the period when the continents separated from each other and the planet began to warm up. This led to a significant expansion of the jungle; Some jungles stretch to the poles. Large in the oceans aquatic reptiles became extinct, and their niche was occupied by sharks. Mammals continued to evolve, but no species grew more than 10 kilograms—or about 22 pounds. The Eocene Epoch began 56 million years ago and ended 33.9 million years ago. Mammals continued to evolve during this period, but were still small in size. It was during this time that early primates, horses and whales began to evolve. Birds occupied the top the food chain, birds, the only time when birds became taller than dinosaurs. Due to the disruption of the Antarctic Circumpolar Current, the Earth began to cool again. This caused the jungle to retreat. Mammals began to gain weight and size. Some of them, in fact, were able to reach gigantic proportions - for example, whales.

The Oligocene Epoch began 33.9 million years ago and ended 23 million years ago. During this period, the grass began to spread across the planet, thanks to the retreat of the world's jungles. This allowed many new species to evolve. This affected cats, dogs, marsupials and elephants. However, grass was not the only plant species that flourished during this time. Evergreen trees also found their niche and began to spread throughout the world. As this era progresses, mammals will continue to grow.

The next period of the Cenozoic era was the Neogene period, and this period lasted from 23.03 million years ago to approximately 2.58 million years ago. It can be divided into two main eras. These eras include the Miocene Epoch and the Pliocene Epoch. During this period, the growth of various animals began, including bovids (bovids), large carnivorous mammals and early primates.

During the Miocene epoch, which began about 23 million years ago and ended 5.3 million years ago, giant jungles and dense forests began to recede and grass gradually began to take over their territories. Many species of mammals began to develop, and these include sea ​​otters and monkeys who continued to divide into different types. Seed plants also began to flourish during this era, with more than 90% of modern seed plants evolving during this period.

The Pliocene Epoch began 5 million years ago and ended about 2.58 million years ago. It was at this time in Earth's history that the planet was experiencing dramatic climate changes. It was at this time that the first Australopithecus appeared in Africa. It was they, according to most scientists, who became the progenitors of the human species. And finally, all the continents of the planet acquired their current shape.

The last period of the Cenozoic era was quaternary period, it began 2.58 million years ago and continues to the present day. During the Pleistocene Epoch (2.58 million years ago to 11,700 years ago), four separate glaciations occurred. It was during this era that Africa began to lose water, which led to the emergence of the Kalahari, Namib and Sahara deserts. At this time, animals such as saber tooth tigers, cave lions, giant sloths and dire wolves. Homo sapiens continued to evolve and, thanks to the end of the drought in Africa, began to spread throughout the world thanks to land isthmuses between continents. Towards the end of this era there was a major extinction event that killed many of the giant animals of the time.

The Holocene era began 11,700 years ago and continues to this day. During much of this time, the climate was fairly stable, and the human species spread throughout the world—developing science and technology to take over the world and developing art, music, and poetry. What will this era give to humanity? No one knows for sure, but it is sure to be a fun ride that is sure to bring even more changes. After all, the Earth is always changing.

And the Paleogene, when the second largest catastrophic extinction of species occurred on Earth. The Cenozoic era is significant for the development of mammals, which replaced dinosaurs and other reptiles that almost completely became extinct at the turn of these eras. In the process of development of mammals, a genus of primates emerged, from which, according to Darwin’s theory, man later evolved. "Cenozoic" is translated from Greek as "New Life".

Geography and climate of the Cenozoic period

During the Cenozoic era, the geographical outlines of the continents acquired the form that exists in our time. The North American continent was increasingly moving away from the remaining Laurasian, and now Euro-Asian, part of the global northern continent, and the South American segment was increasingly moving away from the African segment of southern Gondwana. Australia and Antarctica retreated more and more to the south, while the Indian segment was increasingly “squeezed out” to the north, until finally it joined the South Asian part of the future Eurasia, causing the rise of the Caucasian mainland, and also largely contributing to the rise from water and the rest of the current European continent.

Climate of the Cenozoic era gradually became more severe. The cooling was not absolutely sharp, but still not all groups of animal and plant species had time to get used to it. It was during the Cenozoic that the upper and southern ice caps were formed in the region of the poles, and climate map the earth acquired the zonality that we have today. It represents a pronounced equatorial belt along the earth's equator, and then, in order of removal to the poles, there are subequatorial, tropical, subtropical, temperate, and beyond the polar circles, respectively, the Arctic and Antarctic climate zones.

Let's take a closer look at the periods of the Cenozoic era.

Paleogene

Throughout almost the entire Paleogene period of the Cenozoic era, the climate remained warm and humid, although a constant trend towards cooling was observed throughout its entire length. Average temperatures in the North Sea region ranged from 22-26°C. But by the end of the Paleogene it began to get colder and sharper, and at the turn of the Neogene the northern and southern ice caps were already formed. And if in the case of the North Sea these were separate areas of alternately forming and melting wandering ice, then in the case of Antarctica, a persistent ice sheet began to form here, which still exists today. Average annual temperature in the area of ​​the current polar circles dropped to 5°C.

But until the first frosts hit the poles, renewed life, both in the sea and ocean depths and on the continents, flourished. Due to the disappearance of dinosaurs, mammals completely populated all continental spaces.

During the first two Paleogene periods, mammals diversified and evolved into many different forms. Many different proboscis animals, indicotheriums (rhinoceros), tapiro- and pig-like animals, arose. Most of them were confined to some kind of body of water, but many species of rodents also appeared that thrived in the depths of the continents. Some of them gave rise to the first ancestors of horses and other even-toed ungulates. The first predators (creodonts) began to appear. New species of birds arose, and vast areas of savannas were inhabited by diatrymas - a variety of flightless bird species.

Insects multiplied unusually. Cephalopods have multiplied everywhere in the seas and bivalves. Corals grew greatly, new varieties of crustaceans appeared, but bony fish flourished the most.

The most widespread in the Paleogene were such plants of the Cenozoic era as tree ferns, all kinds of sandalwood, banana and breadfruit trees. Closer to the equator, chestnut, laurel, oak, sequoia, araucaria, cypress, and myrtle trees grew. In the first period of the Cenozoic, dense vegetation was widespread far beyond the polar circles. These were mostly mixed forests, but coniferous and deciduous forests predominated here. broadleaf plants, the prosperity of which the polar nights presented absolutely no obstacle.

Neogene

On initial stage During the Neogene period, the climate was still relatively warm, but a slow cooling trend persisted. The ice accumulations of the northern seas began to melt more and more slowly, until the upper northern shield began to form.

Due to the cooling, the climate began to acquire an increasingly pronounced continental color. It was during this period of the Cenozoic era that the continents became most similar to modern ones. South America united with North America, and just at this time the climatic zonation acquired similarities with modern features. By the end of the Neogene in the Pliocene Earth A second wave of cold snap hit.

Despite the fact that the Neogene was half as long as the Paleogene, it was the period that was marked by explosive evolution among mammals. Placental varieties dominated everywhere. The bulk of mammals were divided into anchyteriaceae, the ancestors of the equine and hipparionidae, also equine and three-toed, but which gave rise to hyenas, lions and other modern predators. At that time of the Cenozoic era, all kinds of rodents were diverse, and the first distinctly ostrich-like ones began to appear.

Due to the cooling and the fact that the climate began to acquire an increasingly continental color, areas of ancient steppes, savannas and woodlands expanded, where the ancestors of modern bison, giraffe-like, deer-like, pigs and other mammals, which were constantly hunted by the ancient Cenozoic animals, grazed in large quantities. predators. It was at the end of the Neogene that the first ancestors of anthropoid primates began to appear in the forests.

Despite the winters of polar latitudes, in equatorial belt The land was still full of tropical vegetation. Broad-leaved woody plants were the most diverse. Consisting of them, as a rule, evergreen forests interspersed and bordered with savannahs and shrubs of other woodlands; subsequently, it was they that gave diversity to the modern Mediterranean flora, namely olive, plane trees, walnuts, boxwood, southern pine and cedar.

There were also various northern forests. There were no evergreen plants here anymore, but most of them grew and took root chestnut, sequoia and other coniferous, broad-leaved and deciduous plants. Later, due to the second sharp cold snap, vast areas of tundra and forest-steppes formed in the north. Tundras have filled all zones with the current temperate climate, and places where until recently they grew wildly rainforests, turned into deserts and semi-deserts.

Anthropocene (Quaternary)

In the Anthropocene period, unexpected warmings alternated with equally sharp cold snaps. The boundaries of the Anthropocene glacial zone sometimes reached 40° northern latitudes. Under the northern ice cap were North America, Europe up to the Alps, the Scandinavian Peninsula, the Northern Urals, and Eastern Siberia.

Also, due to glaciation and melting of the ice caps, there was either a decline or a re-invasion of the sea onto the land. The periods between glaciations were accompanied by marine regression and a mild climate.

On this moment There is one of these gaps, which should be replaced no later than in the next 1000 years by the next stage of icing. It will last approximately 20 thousand years, until it again gives way to another period of warming. It is worth noting here that the alternation of intervals can occur much faster, and may even be disrupted due to interference in earthly natural processes person. It is likely that Cenozoic era may end in a global environmental catastrophe similar to the one that caused the death of many species in the Permian and Cretaceous periods.

Animals of the Cenozoic era during the Anthropocene period, together with vegetation, were pushed to the south by alternately advancing ice from the north. The main role still belonged to mammals, which showed truly miracles of adaptability. With the onset of cold weather, massive animals covered with hair appeared, such as mammoths, megaloceros, rhinoceroses, etc. All kinds of bears, wolves, deer, and lynxes also multiplied greatly. Due to alternating waves of cold and warm weather, animals were forced to constantly migrate. A huge number of species became extinct because they did not have time to adapt to the onset of cold weather.

Against the background of these processes of the Cenozoic era, humanoid primates also developed. They increasingly improved their skills in mastering all kinds of useful objects and tools. At some point, they began to use these tools for hunting purposes, that is, for the first time, tools acquired the status of weapons. And from now on, a real threat of extermination has loomed over various species of animals. And many animals, such as mammoths, giant sloths, and North American horses, which were considered food animals by primitive people, were completely destroyed.

In the zone of alternating glaciations, tundra and taiga regions alternated with forest-steppe, and tropical and subtropical forests were strongly pushed to the south, but despite this, most plant species survived and adapted to modern conditions. The dominant forests between glaciation periods were broadleaf and coniferous.

At the moment of the Cenozoic era, man reigns everywhere on the planet. He randomly interferes with all sorts of earthly and natural processes. Behind last century A huge amount of substances were released into the earth's atmosphere, contributing to the formation of the greenhouse effect and, as a result, faster warming. It is worth noting that faster melting of ice and rising sea levels contribute to disruption of the overall picture of the earth’s climatic development.

As a result of future changes, underwater currents may be disrupted, and, as a consequence, the general planetary intra-atmospheric heat exchange may be disrupted, which may lead to even more widespread icing of the planet following the warming that has now begun. It is becoming increasingly clear that the length of the Cenozoic era, and how it will ultimately end, will now depend not on natural and other natural forces, but on the depth and unceremoniousness of human intervention in global natural processes.

The Quaternary period began 2.6 million years ago and continues to the present day. It is one of three periods (66 million years ago - to the present) and follows (23-2.6 million years ago). The Anthropocene is divided into two eras:

• Pleistocene era, or Pleistocene (2.6 million - 11.7 thousand years ago);
• Holocene epoch, or Holocene (11.7 thousand years ago - to the present).

Geography

Major geographic changes that occurred during this time period included the formation of the Bosporus and Skagerrak straits during the Ice Ages, which respectively turned the Black and Baltic Seas into, and then their inundation (and return of salt water) by rising sea levels; periodic flooding of the English Channel, creation of a land bridge between Great Britain and European part Sveta; the periodic appearance of the land-based Bering Isthmus, forming a bridge between Asia and North America; and periodic flash flooding of the American northwest with glacial water.

The current extent of Hudson Bay, the Great Lakes, and other large lakes in North America is a consequence of the restructuring of the Canadian Shield since the last Ice Age; During the Quaternary period, coastlines constantly changed.

Climate

Throughout the Quaternary period, the planet revolved around the Sun. Small shifts caused ice ages. About 800 thousand years ago a cyclical pattern emerged: glacial period lasted about 100 thousand years, followed by warmer interglacials of 10 thousand to 15 thousand years each. The last ice age ended about 10 thousand years ago. Sea levels rose rapidly and the continents reached their current shape.

As temperatures cooled, ice sheets spread from the poles to cover much of North America and Europe, parts of Asia and South America, and all of Antarctica. With so much water locked in glaciers, sea levels are falling.

Animal world

Birds

During the Quaternary period, birds continued to evolve throughout the world and inhabit a variety of habitats. However, many giant flightless birds have gone extinct, including the dodo, or Mauritian dodo. Large flying birds have also disappeared, including Teratornis merriam, which had a wingspan of more than 3.5 m and a weight of about 15 kg.

Reptiles and amphibians

Extinct reptiles, lizards and turtles were larger than extant ones, and crocodiles were smaller, although snakes did not tend to have a particular body size.

Body size played a complex role in the extinction of late Quaternary reptiles. More large species lizards and turtles have been clearly affected by extinction mechanisms such as overexploitation and introduction invasive species, which led to the predominance of large animals among extinct taxa.

Marine fauna

From the very beginning of the Quaternary period, whales and sharks dominated the seas, and were at the top, above the otters, seals, dugongs, fish, squid, urchins and microscopic plankton that filled the lower trophic level.

Human

In fact, the Quaternary is often considered the "era of men." Homo erectus ( Homo erectus) appeared in Africa early in this period, and developed larger brains and larger high intelligence. First modern people evolved in Africa about 190 thousand years ago and dispersed to Europe and Asia, and then to Australia and America. Our species has greatly changed the land and sea ​​life, and now, according to scientists, humanity is causing global climate change.

Vegetable world

Despite significant climatic differences between the Pleistocene and Holocene epochs, much of it remained unchanged. The Pleistocene era had two main climatic conditions: glacial and interglacial. During the Ice Age, most of the land was covered with ice, and the vegetation was mainly tundra, which included mosses, sedges, shrubs, lichens and low-growing grasses; however, during an interglacial period, or a time when most of the soil was not covered by ice, there were forested areas And coniferous forests. The emergence occurred during the beginning of the Holocene. This habitat allowed many animals and plants to flourish. During this period, conifers and deciduous forests, as well as savannas where herbivores grazed and flourished.

This era is divided into Paleogene, Neogene and Anthropogenic periods. There was a division of the Cenozoic era into two periods - Tertiary and Quaternary, of which the Tertiary united the Paleogene and Neogene, and the Quaternary corresponded to the Anthropocene period.

In the Paleogene and especially in the Neogene, a new powerful folding and mountain formation took place, called the Alpine era. There are several phases of folding, of which the most intense ones occur in the Neogene. During this era, the largest mountainous countries were formed (Atlas, Andalusian mountains, Pyrenees, Apennines, Alps, Carpathians, mountains of the Balkan Peninsula, mountains of Asia Minor, the Caucasus, mountains of Iran, Pamir, Himalayas, mountains South-East Asia and the Malay Archipelago, the mountains of Kamchatka and Sakhalin, the Cor-

dealers and the Andes of North and South America). In addition, in a number of more ancient mountainous countries, already severely destroyed by this time by denudation, new powerful faults arose, uplifts and subsidences occurred (central Europe, Tien Shan, Altai, etc.). Simultaneously with mountain building, which took place mainly in the northern hemisphere, in the southern hemisphere, Australia separated from Asia, the Red Sea depression was formed, deep faults cut East Africa, large faults also spread to the northern hemisphere, where the formation of the northern part of the Atlantic Ocean took place, the depression of which acquired outlines close to modern ones. The areas of volcanism were close to those existing today.

Mountain building, which took place along the outskirts of previously formed platforms, involved these platforms in its movement, and therefore the outlines of the seas changed greatly. On the territory of the USSR, powerful transgressions covered the south of the Russian Plain, Central Asia, and Western Siberia.

The climate in the Paleogene (before the manifestation of intense mountain building) was warm, humid, without sharp temperature fluctuations over vast areas. In the Neogene, the climate becomes more continental, with sharply defined climatic provinces, but remains generally warmer than the modern one.

The flora of the Paleogene and Neogene, which was dominated by angiosperms, is very similar to the vegetation of modern tropical and subtropical latitudes, and these plant species spread in the Paleogene up to the northern islands of Europe and North America. In the Neogene, the area of ​​moisture-loving forests was greatly reduced, and drought-resistant flora and steppe spaces appeared in temperate latitudes.

The Paleogene and Neogene fauna is rich and diverse. On land, various mammals and birds dominate. The marine fauna becomes very close to modern; marine mammals appear. In the Neogene, with the advent of steppe spaces, ungulates (antelope, horses, etc.) quickly began to evolve. At the same time, the development of anthropoids also occurs. In the Neogene deposits of the island of Java, the remains of an ape-man (Pithecanthropus) were found, and in China - a man (Sinatropus), who used stone tools and fire.

Paleogene and Neogene deposits are rich in various minerals, among which oil, gas and coal deposits are very important.

Climate changes that began in the Neogene led at the beginning of the Anthropogen (Quaternary) period to a significant cooling, as a result of which powerful glaciation developed first in the mountains and then on the plains. During the Anthropocene period, these glaciers either grew greatly or sharply shrank to approximately their present size. In this regard, it is customary to distinguish between glacial and interglacial epochs. For Eastern European

plains, most researchers indicate four glaciations: Oka, Dnieper, Moscow and Valdai. The boundaries of the two glaciations are shown in Fig. 28.

Significant climate changes have greatly affected the composition of flora and fauna. During the Anthropocene period, polar and temperate

latitudes are populated by animals and plants adapted to harsh climatic conditions. Instead of the heat-loving Neogene flora, taiga-type forests develop here, and later tundra flora appears.

During this period, the duration of which is relatively short (1 000 000 years), there were no major changes in the outlines of the seas and continents. Small transgressions and regressions of the sea occurred in the coastal strip of the World Ocean during interglacial and postglacial times. The size of closed basins (the Caspian Sea) changed more significantly. In this regard, sediments of marine origin on the area of ​​modern continents are very limited in distribution. Continental deposits (glacial, river, lake, swamp, etc.) are more widespread.

After the intense manifestation of mountain building that occurred in the Neogene, the movements of the earth's crust in the Anthropogene period did not stop and continue to the present day, as evidenced by strong earthquakes, volcanism, uplift and subsidence of large blocks earth's crust, occurring in zones of Alpine folding. All these processes, together with the activity of external geological agents, affect the ancient relief of the lithosphere and are reflected in its modern relief.

In general, the Cenozoic era has now been marked by very important events. 1. A new thing happened - alpine mountain formation (see Fig. 27), mountain structures rose, which are currently the highest mountains on Earth. 2. Mountainous countries that arose in the Paleozoic and Mesozoic era. by the beginning of the Cenozoic they were severely destroyed. During the era of Alpine folding, they experienced repeated movements, were broken by faults, raised to great heights and again turned into mountainous countries with sharp relief forms. 3. There was a further reduction of geosynclines and platforms grew due to them. 4. The uplift of young mountain ranges was accompanied by the uplift of neighboring sections of platforms, which affected the distribution of land and sea. This was also influenced by the faults in the earth's crust that separated the continents. 5. As a result of volcanism, vast lava plateaus and plains were formed, high volcanic mountains and highlands arose, and new mineral deposits were formed in the bowels of the Earth (currently still hidden under a thick sedimentary cover). 6. The climate has changed greatly. From the warm and monotonous characteristic of the beginning of the Cenozoic era, it became sharp, with a large number of climatic zones and provinces. 7. Large glaciers arose, repeatedly spreading over vast expanses of land. 8. Animal and vegetable world took on their modern appearance. 9. A man appeared and began his activities.

Concluding the brief description geological history Earth, it should be noted its complexity. Without touching on the development of the organic world, let us turn to the issues of the development of the lithosphere and its relief, taking the territory of the USSR as an example.

By the beginning of the Paleozoic era, within this territory there were two rigid masses of the earth’s crust: the Russian and Siberian platforms with their most rigid parts, shields. As a result of repeated epochs of folding and mountain building, the pliable zones (geosynclinal belts) located between these platforms, filled with thick strata of sediments, were crushed into folds and turned into mountain structures attached to the outskirts of the platforms or connecting the platforms with each other. This process can be clearly traced in the history of the Ural-Tyan-Shan geosyncline. At the beginning of the Paleozoic era, thick layers of sediment accumulated near the southern edge of the Siberian Platform

and mountain building occurred (the Caledonian folding era), as a result of which mountains arose in the region of modern Baikal region, in the Sayans, in Altai. For the rest of the geosynclinal belt, this era was expressed as preliminary, since the mountains that emerged here quickly collapsed and were again largely flooded by the sea (Kazakhstan, Western Altai, etc.). Along the outskirts of the emerging mountainous countries, in actively sagging areas of the not yet closed parts of the geosyncline, the accumulation of new sediment layers continued, culminating in new folding and mountain building, which developed at the end of the Paleozoic era (Hercynian era). Vast mountainous countries were formed: the Urals, Tien Shan, the Kazakh mountainous country and mountains on the site of a significant part of the West Siberian Lowland. Further history of these mountainous countries is different. Most of them were destroyed by denudation agents, experienced subsidence and are currently located under a thick layer of Meso-Cenozoic sediments that make up the sedimentary cover of the West Siberian Lowland. The marginal western part, which has experienced minor uplifts as a result of recent movements, stretches along the edge of the Russian Platform in the form of the low Ural Mountains. Significant areas of the ancient mountainous country, heavily destroyed by denudation agents, which did not experience significant uplifts and subsidences, are observed in Central Kazakhstan. The southernmost parts of the ancient mountainous country, once already destroyed to the state of small hills and later under the influence of powerful mountain-building movements of the era of Alpine folding, were broken into blocks and raised to great heights, which led to the formation of the mountainous terrain of the Tien Shan.

The given example indicates that the earth's crust develops according to the general plan from a flexible geosyncline, through a mountain structure to a rigid platform with a flat topography. in different parts it achieves this in different ways. These paths are often clearly reflected in the relief and can explain its diversity.

GEOLOGICAL MAPS AND PROFILES General information about geological maps

Among maps reflecting natural phenomena, one of the first places is occupied by geological maps created as a result of geological surveying. A geological map gives an idea of ​​the geological structure of the site earth's surface and is essentially a vertical projection of bedrock outcrops mapped onto a topographic base of a certain scale. Such a map is called a geological map itself, since its construction is based on the principle of identifying rock strata of different ages.

A geological map is the basis for all other maps produced in comprehensive geological mapping. The latter involves the compilation of a number of maps highlighting individual aspects of the geological structure of the area. The noted complex of maps includes: lithological-petrographic, structural-tectonic, hydrogeological, facies-paleogeographic, geomorphological, engineering-geological, various geophysical, minerals.

Depending on the scale, all geological maps are divided into overview, regional medium-scale and large-scale.

Overview maps highlight the structure of individual continents and states. The largest scale is 1: 1,000,000. The topographical basis is simplified.

Regional maps (small-scale) - display a section of the earth's surface characterized by the unity of its geological structure (Caucasus, Urals, Donbass, etc.). The scale of the maps is from 1: 1,000,000 to 1: 200,000. The topographic basis is simplified.

Medium-scale - display in detail the geology of a relatively small area. Their scale is from 1: 200,000 to 1: 25,000. The topographic basis is simplified.

Large-scale geological maps - compiled for mineral deposits. Scales from 1: 1000 to 1: 500. The topographic basis is often compiled specially.

Geological work in the field usually begins with reconnaissance routes, which make it possible to get a general idea of ​​the area and identify the features of its individual parts. After reconnaissance, the plan for field work and research is clarified, time is allocated and the sequence of routes is outlined. Great importance at the same time, it has a degree of exposure of the area, which can be judged with a sufficient degree of reliability from aerial photographs.

The most complete ones are subject to priority research - reference outcrops (sections) or wells with continuous core sampling (rock samples obtained from wells during the drilling process). Intermediate outcrops, in which only parts of the main section are exposed, are explored later.

Simultaneously with the description of natural and artificial sections, the altitudinal and plan reference of the marking (reference) layers and horizons identified in them, which are important for mutual coordination, is carried out. Depending on the scale of the shooting, the reference can be instrumental or visual. When describing the stratigraphic sequence of layers in sections, their thickness and occurrence elements must be measured. As a result, a summary section (column) is compiled.

Comparison of sections and tracing of identified stratigraphic units throughout the entire area of ​​the region make it possible

get an idea of ​​their structure (forms of occurrence) and facial changes. Linking the outcrops of these layers to the earth's surface makes it possible to draw the contours of the age boundaries of bedrock (pre-Quaternary) rocks on a topographic map - to create a geological map.

Actually geological maps

The methodology for compiling a geological map depends on the scale of the survey, exposure and mainly on the geological structure of the area. It is different for horizontal, inclined and folded layers.

Horizontal occurrence is characterized by close values ​​of the absolute elevations of the roof or base of the layer. Depending on the depth of dissection of the mapped terrain, when lying horizontally on the surface, either only the upper layer (with shallow dissection) or deeper layers (with deep dissection) will be exposed. The horizontal occurrence of layers is easily determined by the coincidence or almost parallel arrangement of the outcrops of the mapped layer and the contours of the topographic base (Fig. 29).

If the layers are removed from their original horizontal position and have acquired a slope in one direction, then their occurrence is called monoclinal (single-sloping). To determine the position of monoclinal layers in space, the method of finding the lines of strike and dip of layers is used. The straight line that is obtained when the monoclinal layer intersects with a horizontal plane is called the strike line (Fig. 30). The dip line is located perpendicular to the strike line, directed in the direction of the greatest inclination of the layer. Determination of bedding elements, orientation of strike and dip lines according to the cardinal points is carried out using a mountain compass.

As mentioned above, when lying horizontally, the lines of the layers' outcrops will coincide with the contour lines of the topographic map or be located parallel to them. When lying vertically, the terrain will not affect the configuration of the lines of intersection of the layer with the plane, since all strike lines are projected in this case onto the plane in one line, which will be straight when straight vertical layer and a curve with a curved vertical surface.

In addition to the above two extreme cases of images on the projection plane of horizontally and vertically lying layers, there can be an infinite number of options for projections of inclined layers, and their configuration will be directly dependent on the angle of incidence and the terrain. With a highly dissected topography and a gentle dip of the layers, the formation exit will have a more complex contour than with a steep bedding of the layers and a weak

boom dismemberment of the relief. The direction of dip of inclined layers on geological maps is determined by their age sequence. The slope will always be towards the location of younger sediments (Fig. 31).

The folded forms of occurrence of layers significantly influence the pattern of the geological map. The exits of the selected age divisions are located in stripes closed by rounded or ellipsoidal contours. Coeval layers within a fold are always located symmetrically with respect to its central (axial) part, which does not have a paired exit. When reading geological maps depicting a folded structure, it is first necessary to determine the age relationships of the layers in order to establish the position of symmetrically located strips of ancient and young layers in relation to the central unpaired strip. The position of the latter determines the presence of the axial part of an anticline or syncline. At the core of the anticline there are always older layers outcropping, bordered by outcrops of layers of younger sediments. On the contrary, the core of the syncline contains younger layers surrounded by more ancient ones (Fig. 32).

Tectonic disturbances on a geological map are depicted as lines breaking geological boundaries. The image of displacements of age boundaries in the plan and the configuration of fault lines depend on the type of structure, the angles of incidence of layers, the angle of inclination of the ejector and other reasons.

When geological mapping of igneous rocks, the relationship of the latter with the host strata is taken into account. Inter-

the relationship between intrusions is presented differently in the study of intrusive rocks that have penetrated into the sedimentary layer of the earth's crust and are exposed due to denudation processes and igneous rocks formed on the surface of the earth as a result of volcanic processes. Geological maps depict the outline of the outcrops of magmatic bodies and, using indices, indicate their age and geological composition.

When compiling geological maps, established symbols of three types are used: color; indexes (letter and numeric); lined.

Color symbols determine the age of the rocks, and when depicting intrusion outcrops, their composition. Indices - determine the age of the identified units and sometimes their origin (intrusions and effusions indices). Line symbols can replace color symbols or, when applied to a color background, indicate the composition of rocks. Standards for color symbols for divisions of the geochronological scale were proposed by the Russian geologist A.P. Karpinsky and approved in 1881 by the II International Geological Congress.

The geochronological scale uses two types of divisions. Some correspond to the time period of the selected unit, others are thicker than the rocks formed at that time. Accordingly, an era is parallelized with a group, a period with a system, an era with a department, a century with a tier, and time with a zone.

Color marking standards are adopted for period systems.

Anthropocene period, system - light gray color

Neogene »» -yellow

Paleogene » » -orange

Chalk » » -green

Jurassic » » -blue

Triassic » » -violet

Perm » » -brown-red

Coal » » -gray

Devon » » -brown

Silurian » » - light olive

Ordovician » » -olive dark

Cambrian "" - pink

Outcrops of Archean (AR) and Proterozoic (PR) rocks are indicated in various shades of red (large-scale maps of areas of the indicated age are colored with the colors and strokes adopted for igneous rocks and formations). More detailed divisions of the geochronological scale (divisions, stages, etc.) are painted over with the tones of the main color of the period (system), and the density of the tone weakens from ancient divisions to young ones.

When compiling a geological map at a scale larger than 1:100,000, a standard color scale may not be sufficient. In this case, symbols are added in the form of specks, stripes and others, but in the colors adopted for of this period(systems).

Igneous rocks are indicated by bright colors with indices corresponding to the name of the rocks. Acidic and intermediate rocks are indicated in red, alkaline rocks in orange, mafic rocks in green, and ultramafic rocks in purple.

Extrusive rocks on the maps of the old edition were designated by different colors with indices assigned in accordance with the composition of the rocks. Acidic effusives were colored orange, basic ones - green. On maps of the latest editions, volcanic rocks are painted over with a color indicating their age, with the addition of indices and strokes that determine the composition of the rocks.

The system (period) index is used as the basis for the letter and digital designation of sedimentary, igneous and metamorphic rocks on the geochronological scale and on the geological map. When designating a department, a number corresponding to the lower, middle, upper departments (epochs) is added to it, or when divided into two parts - lower and upper. When dividing a department (epoch) into tiers (centuries), letter designations are added to the index of the department (epoch), consisting of the first letter of the name of the tier and the first consonant letter in this name. This can be illustrated by the example of the index of the Cretaceous system (period): the index of the system (period) - (K), the indices of departments (epochs) - (K 1) and (K 2), the index of one of the tiers (centuries) - Valanginian - TO 1 v. Parts

tiers are indicated in Arabic numerals, placed at the bottom right of the index - TO 1 v 1 .

On detailed geological maps, at the top right, above the period (system) index, indices are sometimes placed indicating the facies composition of the rocks: T- marine sediments, J- lake, h- coal-bearing, f- flysch *.

In addition to age, there is often a need to identify local units that correspond to certain stages of the geological development of a given area. In this case, the rocks are divided into series, formations, subformations, and horizons. Whenever possible, local units are aligned with the generally accepted age scale. Local subdivision indices are formed from two lowercase Latin letters (the first letter of the name and the nearest consonant). The letters are written to the right of the group, system or department index. For example: J 1 bg- Lower Jurassic section, Bezhitinskaya suite.

For a division covering two adjacent departments or systems, the index is formed by connecting them with a + (plus) sign or a - (hyphen) sign. The + sign is placed if two neighboring divisions, represented in their full development J + K, are combined; a dash (hyphen) is used in all other cases. The J-K index indicates the presence of Cretaceous and Jurassic contact in the selected unit without determining their more precise age boundaries.

On geological maps, if color symbols are replaced by dashed symbols, the latter are chosen arbitrarily. When depicting the composition of rocks, line symbols have a certain standard.

A geological section is an image of the sequence of bedding and the structure of layers of the surface parts of the earth's crust in a vertical section. When constructing a section with any occurrence of layers, its horizontal scale must correspond to the scale of the map. The choice of vertical scale depends on the thickness of the layers. The thinnest layer in the chosen scale should not be less than 1 mm. Ideally, the vertical scale value should be equal to the horizontal scale. In this case, there will be no distortion in the angles of incidence and powers on the profile.

When the layers are inclined and folded, it is necessary to take into account the direction of the profile section in relation to the line of strike of the inclined and folded layers; to eliminate the distortion of the angles, a correction calculated from special tables must be introduced.

When the layers occur horizontally, the most complete section will be the one whose line passes through the highest and lowest point relief. To construct a horizontal section

*Flysch - thick, uniform and rhythmic in structure sedimentary strata of shallow marine sediments.

layers on a geological map, the intersection of geological boundaries with the profile line on the map should be transferred to the terrain profile and connect the resulting points with horizontal lines.

When constructing a geological section with inclined layers, it is necessary to remember that a section constructed in the direction of dip, with equal vertical and horizontal scales, will always have the true angle of inclination of the layers and thickness. In the case when the cut runs in the direction of strike, the layers have a horizontal position.

When constructing a profile section based on a geological map, reflecting the folded occurrence of layers, as well as with horizontal and inclined occurrence, first of all, a topographic profile is constructed on the scale adopted for vertical constructions. Outcrops of geological boundaries and dip angles on the wings of folds are plotted on the topographic profile. Then the geological section is drawn taking into account the position of the axial surfaces of the folds in plan.

The compilation of profile sections crossing the territory with the outcrops of cutting intrusions requires solving problems that are not considered in the program of this book. In general, when a section passes through an intrusion, it should be shown as a body that interrupts the bedding of layers in the same way as in discontinuous faults.

Engineering-geological maps

Engineering-geological maps reflect the engineering-geological conditions of the mapped territory and provide a comprehensive natural assessment necessary for construction. The task of engineering geology is to determine the geological features of the study area in order to establish its suitability for the construction and operation of engineering structures.

The geological structure influences the choice of location, layout, structure design and methods of construction work.

An engineering-geological map, together with profile sections, stratigraphic columns and a comprehensive description of soils, is the main document obtained as a result of engineering-geological surveys. Among engineering-geological maps for various purposes, general overview, special overview, schematic and detailed maps are usually distinguished. General overview maps are used for designing various types of construction and are compiled on a small scale (1: 200,000 and smaller). The remaining categories of hags are used to design a specific type of engineering structures and are compiled on a scale that meets the construction requirements.

When conducting geological surveys and drawing up a map, the nature of the relief and geological structure must be taken into account.

tur, rock composition, hydrogeological conditions and dynamics of modern processes. Information about the terrain is necessary for selecting a construction site, estimating the volume of excavation work, laying access roads and other design data. The geological structure gives an idea of ​​the occurrence of bedrock and the position of their roof in relation to the modern hydrographic network. The composition of rocks (ground conditions) is subject to particularly careful study and is depicted on the map in accordance with the established geological and petrographic classification.

The study of water content is essential. On the maps, symbols indicate the depth of occurrence. groundwater, water abundance, pressure, chemical characteristics. In some cases (on large-scale maps), the groundwater surface is depicted as isolines. The dynamics of modern geological processes are reflected on large-scale maps by symbols and boundaries outlining the areas in which certain processes develop (landslides, karst, permafrost, rock subsidence, various forms of erosion, etc.). The qualitative and quantitative assessment of dynamic processes is indicated on the maps, and the intensity of the development of the process is indicated.

When preparing an engineering geological map, it is essential to select colors and symbols that determine its clarity and ease of reading.

Tectonic maps

Tectonic maps depict structural elements of various scales, categories, and ages.

Drawing up tectonic maps is one of the most important and active ways of studying and analyzing the development of structures of the earth's crust. Depending on the size of the territory for which the map is drawn up, the scale and symbols, it is customary to distinguish between general (summary) and regional tectonic maps. In addition, to display the morphology of tectonic structures, so-called structural maps are compiled. General tectonic maps depict large-scale structural elements that are the main structures of the earth's crust. The symbols (legend) used in the preparation of such maps are common to the entire surface of the Earth and can be used in any of its regions. Regional maps reflect the structure of a specific area of ​​the earth's crust; the symbols adopted for it may be of little use for using them when drawing up a map of another area.

The surface relief of a particular structure depicted on a tectonic map is conveyed using isolines (horizontals) connecting points with equal elevations, calculated from the level of the World Ocean.

The starting point for general tectonic mapping is to establish the age of folding of the main structures,

time of formation of the geosyncline, i.e. in time

graduation geosynclinal and the beginning of the platform stages of development of the study area. The moment of transformation of a geosynclinal folded system into a platform is a natural milestone in the development of the earth's crust.

Within Europe and neighboring parts of other continents, territories are distinguished that experienced the following main folding epochs, the age of which is determined by the time of completion of the geosynclinal stage of development: Precambrian (Archean and Proterozoic), Baikal, Caledonian, Hercynian and Alpine. Larger divisions (cycles) in the development of the earth's crust, combining many eras and periods (stages) of folding, are called megachrons. In the history of the formation of the earth's crust, several megachrons can be distinguished, but the most studied is the last one, called Neogean. In this new, last megachron, a radical restructuring of the earth's crust and the formation of its modern structure took place. The age of these structures is reflected on tectonic maps with special indices and colors.

On tectonic maps of the territory of the USSR, for the Baikal folding (Proterozoic) it is accepted Blue colour, for Caledonian - lilac, for Hercynian (Variscian) - brown, for Alpine - yellow. Older megachrons are depicted in shades of red.

When depicting different zones geosynclinal areas - eugeosynclines and miogeosynclines, shades of colors are used that determine the age of a particular folded structure and a letter index is put. For example, the eugeosyn-clinal zone of the Caledonian folding is designated by the index - eC. Structural floors in folded structures are also distinguished by the density of the tone of the accepted age coloring, with the lower structural floors being painted with a more intense shade. Letter indices are supplemented by numbers. K 1, for example, denotes the lower floor of the Karelian folding (Proterozoic), C 2 - the middle floor of the Caledonian folding, A 3 - the upper structural floor of the Alpine folding, etc. There are alphabetic and numerical designations for more fractional divisions - subfloors. For example, A 2 1 is the upper sublevel of the lower structural level of Alpine folding.

Marginal troughs are indicated by a banded horizontal coloration of the color of the upper structural floor of a given fold. In the case of covering the marginal deflection with a platform cover, translucent shading is used under the paint of the platform cover. Internal intermountain depressions, developing simultaneously with marginal troughs, are indicated by the color of the upper structural floor with specks of molasse *. The middle massifs are painted over

*Molasses are clastic rocks that fill deep troughs of geosyn-clinal zones V main epochs of mountain building.

are colored by folding, which turned them into hard blocks (for example, the Hercynian massifs among the structures of Alpine folding in the Caucasus, etc.).

With the introduction into the legend of general tectonic maps of the designations of eu- and miogeosynclines, structural levels and internal depressions with appropriate detail of the contours, these maps raise their accuracy to the level of regional maps.

Within platform structures, general tectonic maps highlight areas of outcrops of folded foundations (shields) and slabs, in the area of ​​which the foundation is covered by a sedimentary cover. On the shields and exposed arches of the anteclises, the folded foundation is divided according to the eras of folding with the identification of structural floors. In the slab territory, the surface of the folded foundation is depicted using isohypses and step coloring, highlighting the areas of subsidence and uplift. (Submerged areas are lighter in color than uplifted areas.) The age of the platforms is emphasized on tectonic maps by a certain color, which differs from the folded areas in a paler tone. To indicate the sedimentary cover of platforms, the following color tones are adopted: the sedimentary cover of ancient platforms is indicated by a brownish-pink color, of the Epicaledonian ones - violet-green, of the Hercynian platforms - brownish-gray.

Outcrops of intrusive massifs are depicted in the same way as on geological maps, within the limits of their modern erosional section. Intrusions are subdivided according to their belonging to certain stages of tectogenesis (early orogenic, late orogenic and anorogenic). The age of intrusions is indicated by indices, the composition - by color and icons adopted for geological maps.

Large faults are depicted on general tectonic maps as solid and dotted red lines. In addition, tectonic maps show zones of intensive development of metamorphism and centers of modern and ancient volcanism.

Symbols have been developed in great detail to indicate folds and faults shown on tectonic maps, as well as to indicate boundaries and lines separating structures of different orders and ages.

The periods of the geological history of the Earth are epochs, the successive changes of which shaped it as a planet. At this time, mountains were formed and destroyed, seas appeared and dried up, ice ages succeeded each other, and the evolution of the animal world took place. The study of the geological history of the Earth is carried out using sections of rocks that have preserved mineral composition period that formed them.

Cenozoic period

The current period of Earth's geological history is the Cenozoic. It began sixty-six million years ago and is still going on. The conditional boundary was drawn by geologists at the end Cretaceous period when there was a mass extinction of species.

The term was proposed by the English geologist Phillips back in the mid-nineteenth century. Its literal translation sounds like “ new life" The era is divided into three periods, each of which, in turn, is divided into eras.

Geological periods

Any geological era divided into periods. IN Cenozoic era There are three periods:

Paleogene;

The Quaternary period of the Cenozoic era, or Anthropocene.

In earlier terminology, the first two periods were combined under the name "Tertiary period".

On land, which had not yet completely divided into separate continents, mammals reigned. Rodents and insectivores, early primates, appeared. Reptiles have been replaced in the seas predatory fish and sharks, new species of mollusks and algae appeared. Thirty-eight million years ago, the diversity of species on Earth was amazing, and the evolutionary process affected representatives of all kingdoms.

Just five million years ago the first people began to walk on land. apes. Another three million years later, in the territory belonging to modern Africa, Homo erectus began to gather in tribes, collecting roots and mushrooms. Ten thousand years ago, modern man appeared and began to reshape the Earth to suit his needs.

Paleography

The Paleogene lasted forty-three million years. The continents in their modern form were still part of Gondwana, which was beginning to split into separate fragments. South America was the first to float freely, becoming a reservoir for unique plants and animals. In the Eocene era, the continents gradually occupied their current position. Antarctica separates from South America, and India moves closer to Asia. A body of water appeared between North America and Eurasia.

During the Oligocene epoch, the climate becomes cool, India finally consolidates below the equator, and Australia drifts between Asia and Antarctica, moving away from both. Due to temperature changes by South Pole Ice caps form, causing sea levels to drop.

During the Neogene period, the continents begin to collide with each other. Africa “rams” Europe, as a result of which the Alps appear, India and Asia form the Himalayan mountains. In the same way the Andes appear and Rocky Mountains. In the Pliocene era, the world becomes even colder, forests die out, giving way to steppes.

Two million years ago, a period of glaciation began, sea levels fluctuated, and the white caps at the poles either grew or melted again. The flora and fauna are being tested. Today, humanity is experiencing one of the stages of warming, but on a global scale the ice age continues to last.

Life in the Cenozoic

The Cenozoic periods cover a relatively short period of time. If you put the entire geological history of the earth on a dial, then the last two minutes will be reserved for the Cenozoic.

The extinction event that marked the end of the Cretaceous period and the beginning new era, wiped off the face of the Earth all animals that were larger than a crocodile. Those who managed to survive were able to adapt to new conditions or evolved. The drift of the continents continued until the advent of people, and on those of them that were isolated, a unique animal and plant world was able to survive.

The Cenozoic era was distinguished by a large species diversity of flora and fauna. It is called the time of mammals and angiosperms. In addition, this era can be called the era of steppes, savannas, insects and flowering plants. Crown evolutionary process The appearance of Homo sapiens on Earth can be considered.

Quaternary period

Modern humanity lives in the Quaternary epoch of the Cenozoic era. It began two and a half million years ago, when in Africa great apes They began to form tribes and obtain food for themselves by collecting berries and digging up roots.

The Quaternary period was marked by the formation of mountains and seas and the movement of continents. The earth acquired the appearance it has now. For geological researchers, this period is simply a stumbling block, since its duration is so short that radioisotope scanning methods of rocks are simply not sensitive enough and produce large errors.

The characteristics of the Quaternary period are based on materials obtained using radiocarbon dating. This method is based on measuring the amounts of rapidly decaying isotopes in soil and rock, as well as the bones and tissues of extinct animals. The entire period of time can be divided into two eras: the Pleistocene and the Holocene. Humanity is now in the second era. There are no exact estimates yet of when it will end, but scientists continue to build hypotheses.

Pleistocene era

The Quaternary period opens the Pleistocene. It began two and a half million years ago and ended only twelve thousand years ago. It was a time of glaciation. Long ice ages were interspersed with short warming periods.

One hundred thousand years ago in the area of ​​modern Northern Europe a thick ice cap appeared, which began to spread in different directions, absorbing more and more new territories. Animals and plants were forced to either adapt to new conditions or die. The frozen desert stretches from Asia to North America. In some places the ice thickness reached two kilometers.

The beginning of the Quaternary period turned out to be too harsh for the creatures that inhabited the earth. They are used to the warmth temperate climate. In addition, ancient people began to hunt animals, who had already invented the stone ax and other hand tools. Entire species of mammals, birds and marine fauna are disappearing from the face of the Earth. The Neanderthal man could not withstand the harsh conditions either. Cro-Magnons were more resilient, successful in hunting, and it was their genetic material that should have survived.

Holocene era

The second half of the Quaternary period began twelve thousand years ago and continues to this day. It is characterized by relative warming and climate stabilization. The beginning of the era was marked mass extinction animals, and it continued with the development of human civilization, its technological flourishing.

Changes in animal and plant composition throughout the era were insignificant. Mammoths finally became extinct, some species of birds and marine mammals. About seventy years ago the general temperature of the earth increased. Scientists attribute this to the fact that human industrial activity causes global warming. In this regard, glaciers in North America and Eurasia have melted, and the Arctic ice cover is disintegrating.

glacial period

An ice age is a stage in the geological history of the planet that lasts several million years, during which there is a decrease in temperature and an increase in the number of continental glaciers. As a rule, glaciations alternate with warming periods. Now the Earth is in a period of relative temperature rise, but this does not mean that in half a millennium the situation cannot change dramatically.

At the end of the nineteenth century, geologist Kropotkin visited the Lena gold mines with an expedition and discovered signs of ancient glaciation there. He was so interested in the findings that he began large-scale international work in this direction. First of all, he visited Finland and Sweden, as he assumed that it was from there that the ice caps spread to Eastern Europe and Asia. Kropotkin's reports and his hypotheses regarding the modern Ice Age formed the basis of modern ideas about this time period.

History of the Earth

The ice age the Earth is currently in is far from the first in our history. Cooling of the climate has happened before. It was accompanied significant changes in the relief of continents and their movement, and also influenced the species composition of flora and fauna. There could be gaps of hundreds of thousands or millions of years between glaciations. Each ice age is divided into glacial epochs or glacials, which during the period alternate with interglacials - interglacials.

There are four glacial eras in the history of the Earth:

Early Proterozoic.

Late Proterozoic.

Paleozoic.

Cenozoic.

Each of them lasted from 400 million to 2 billion years. This suggests that our ice age has not even reached its equator yet.

Cenozoic Ice Age

Animals of the Quaternary period were forced to grow additional fur or seek shelter from ice and snow. The climate on the planet has changed again.

The first epoch of the Quaternary period was characterized by cooling, and in the second there was relative warming, but even now, in the most extreme latitudes and at the poles, ice cover remains. It covers the Arctic, Antarctic and Greenland. The thickness of the ice varies from two thousand meters to five thousand.

The Pleistocene Ice Age is considered to be the strongest in the entire Cenozoic era, when the temperature dropped so much that three of the five oceans on the planet froze.

Chronology of Cenozoic glaciations

The glaciation of the Quaternary period began recently, if we consider this phenomenon in relation to the history of the Earth as a whole. It is possible to identify individual epochs during which the temperature dropped especially low.

1. The end of the Eocene (38 million years ago) - glaciation of Antarctica.
2. The entire Oligocene.
3. Middle Miocene.
4. Mid-Pliocene.
5. Glacial Gilbert, freezing of the seas.
6. Continental Pleistocene.
7. Late Upper Pleistocene (about ten thousand years ago).

This was the last major period when, due to climate cooling, animals and humans had to adapt to new conditions in order to survive.

Paleozoic Ice Age

IN Paleozoic era The ground froze so much that ice caps reached Africa and South America in the south, and also covered the entire North America and Europe. Two glaciers almost converge along the equator. The peak is considered to be the moment when a three-kilometer layer of ice rose above the territory of northern and western Africa.

Scientists have discovered the remains and effects of glacial deposits in studies in Brazil, Africa (in Nigeria) and the mouth of the Amazon River. Thanks to radioisotope analysis, it was found that age and chemical composition of these finds is the same. This means that it can be argued that the rock layers were formed as a result of one global process that affected several continents at once.

Planet Earth is still very young by cosmic standards. She is just beginning her journey in the Universe. It is unknown whether it will continue with us or whether humanity will simply become an insignificant episode in successive geological eras. If you look at the calendar, we have spent a negligible amount of time on this planet, and it is quite simple to destroy us with the help of another cold snap. People need to remember this and not exaggerate their role in the Earth's biological system.