The development of life on earth in the Cenozoic era. Development of life in the Cenozoic. Geology, climate, flora and fauna The Quaternary period briefly

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 of southeast Asia and the Malay archipelago, mountains of Kamchatka and Sakhalin, Cor-

dealers and the Andes of Northern 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 took place Atlantic Ocean, 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 greatly decreased, temperate latitudes drought-resistant flora and steppe spaces appeared.

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 eras. 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. The animal and plant world took on their modern appearance. 9. A man appeared and began his activities.

Concluding this brief description of the geological history of the Earth, we should note 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.

Back to top 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, the 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 an area of ​​the earth's surface and is essentially a vertical projection of bedrock outcrops plotted on 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 three types: colored; 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 a given period (system).

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 drawings conventional signs 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 selected 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 characterization. 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

On tectonic maps structural elements of various scales, categories and ages are depicted.

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.

Quaternary period or Anthropocene - the third period of the era, the last, on this moment, period of Earth's history. The Quaternary period began 2.588 million years ago and continues today. You can get acquainted with the complete geochronological scale of the history of the Earth. The duration of the Anthropocene is unknown, since its change requires a noticeable change in conditions on the planet.

The Quaternary period is divided into two eras: (2.588 million years ago - 11.7 thousand years ago) and (11.7 thousand years ago - today).

The Quaternary period is the shortest geological period of all the identified periods in the history of the Earth. However this period incredibly rich in events in the field of relief formation and the development of life. By the way, it was during this period that man appeared, who evolved from great apes, appeared in .

The first epoch of the Quaternary period (Pleistocene) is the time of glacial glaciations. Often, glaciers occupied gigantic territories, turning thousands of kilometers into icy deserts. Ice caps covered vast areas of Europe, Asia and North America. During the Great Glaciation of the Earth, glaciers in some places reached two kilometers in height. Glaciation periods were followed by relatively warm periods when the glaciers retreated.

Due to the glaciation of the Earth, life forms on the planet also changed. Glaciers pushed animals from their habitable places to new lands. Some animals, for example, the mammoth and the woolly rhinoceros, adapted to the new conditions, gaining thick fur and a thick layer of subcutaneous fat. Many scientists believe that it is precisely the difficult conditions ice age in the Pleistocene contributed to faster human evolution. At the end of the Pleistocene and the beginning of the Holocene, animals such as mammoths, mastodons, saber-toothed cats, giant sloths, big-horned deer, cave bears, cave lions and others. Scientists attribute this to climate change. Also, the reduction of animal ranges and the complete extinction of some species are associated with the actions of human ancestors, who by the beginning of the Holocene had evolved into Homo sapiens. In particular, it is believed that the Cro-Magnons (human ancestors) could exterminate not only some species of animals that were hunted for food and skins, but also all that lived at the same time, but could not withstand the competition of a stronger species.

The Holocene, which began 11.7 thousand years ago, is characterized by a relatively stable climate. It is considered a typical interglacial epoch. Many animal species became extinct during this period, but overall changes in fauna and flora are considered minor. It is noted that the Holocene climate is becoming warmer over time. This is also associated with human activity. The formation of human civilization began in the mid-Holocene.

Quaternary (anthropogenic) system (period) isolated by the French scientist J. Denoyer in 1829, it is divided into four sections - lower, middle, upper and modern. Sediments are represented mainly by continental sediments. Marine sediments are not widespread on continents. Igneous rocks - exclusively volcanic - have little development. Metamorphic rocks are unknown. The beginning of the period was characterized by sharp cooling and periodically recurring glaciations in the northern hemisphere. In northern Europe and Asia, at least three glaciations have been established, separated by relatively warm interglacial epochs. There are also several glaciations in North America.

The fauna of the Quaternary period differs little from the modern one. The greatest differences are observed during glacial times, when cold-loving species of animals appeared in Europe, south of the glacier's borders - the musk ox, reindeer, mammoths (Fig. 128), hairy rhinoceroses (Fig. 129), cave bears, etc. At the beginning of the period, ancient ancestors person. In Quaternary deposits there are bones of primitive people and traces of their life activity (fireplaces, stone tools, household items, etc.). In younger Quaternary deposits since the appearance reasonable person (Homo sapiens) Numerous tools and traces have been preserved primitive culture: remains of drawings on the walls of caves, figures of various animals carved from bones, etc.

From brief overview development of the organic world, its repeated sharp changes during the geological history of the Earth are clearly established. Periods of magnificent development and prosperity of some groups of animals and plants are followed by periods of decline and even complete extinction. The dramatic renewal of the animal world coincides with the boundaries between eras in the geochronological table. Moments of a sharp turning point in the development of the organic world and changes in fauna and flora are known in Russian literature under the name “critical epochs”. Currently, five critical epochs have been established and are universally recognized, when there was a particularly strong change in the composition of the organic world and the extinction of many organisms.

The first era refers to the end of the Silurian period, the second - to the end of the Paleozoic era, the third - to the end of the Triassic, the fourth - to the end of the Mesozoic and the fifth - to the end of the Paleogene. During the first critical epoch, a sharp reduction in graptolites, trilobites, and nautiloids was observed; several families of brachiopods and a number of groups of representatives died out sea ​​urchins, several genera of corals, etc.

At the end of the Paleozoic in the second era, a much greater renewal of the organic world occurs. During the second critical epoch, numerous fusulines and schwagerinas, four-rayed corals (rugosas) and tabulates, many families of brachiopods, completely died out. sea ​​lilies, sea urchins, the last representatives of trilobites, goniatites, many families of fish, many representatives of amphibians - stegocephals, etc. Many representatives of fern-like plants also disappear.

The third era comes to an end Triassic period, when most families and genera of Triassic ammonites, the last stegocephalians and some reptiles became extinct. In the fourth critical epoch, ammonites and belemnites, some families of protozoa, pelecypods, brachiopods, crinoids, terrestrial, aquatic and aerial reptiles, toothy birds, etc. died out. In the fifth epoch, at the end of the Paleogene, nummulites, many representatives of mammals, etc. died out.

Extinct animals are replaced by animals of other families, classes and genera, the remains of which are unknown in more ancient layers.

From the analysis of the geochronological table, it can be seen that major changes in the composition of vegetation do not correspond to critical epochs and do not correspond to the boundaries of eras that are established on the basis of the development of animals. Vegetation is significantly ahead of animals in its development. The change in vegetation types does not correspond to critical epochs, eras of extinction and renewal of fauna. Paleozoic vegetation undergoes major changes already in the Permian period. Many representatives of Carboniferous ferns die out in the Early Permian. In the Late Permian period, representatives of gymnosperms, which are the most characteristic and predominant plants of the Mesozoic era, were already widely developed.

At the end of the Mesozoic (in the deposits of the upper Lower Cretaceous), the appearance of the first angiosperms (deciduous, flowering, cereals) is noted, which in the Late Cretaceous and Cenozoic era are the dominant types of flora.

Thus, changes in the composition of vegetation occurred much earlier than changes in the composition of fauna, approximately by half and somewhat even more than half geological period. According to the era of development various forms vegetation is distinguished under the names: 1) paleophytic (ancient plants), covering the end of the Proterozoic, Cambrian, Ordovician, Silurian, Devonian, Carboniferous and early Permian; 2) mesophytic (medium plants), including the late Permian, Triassic, Jurassic periods and early Cretaceous; 3) Cenophyte, or neophyte (new modern plants), begins with the Late Cretaceous and continues to the present day.

The process of development of the organic world in geological history was far from uniform. Moments of magnificent flourishing of some groups of animals are followed by eras of slow, gradual decline and complete extinction of previously thriving animals. These periodic changes in the development of the animal world are explained by the significant variability of physical and geographical conditions throughout the entire geological history of the Earth's development. The physical and geographical situation did not remain constant and unchanged, but changed repeatedly throughout the Paleozoic, Mesozoic and Cenozoic. Changes in physical and geographical conditions influenced changes in the organic world. The change in physical and geographical conditions, in turn, was determined by the reasons causing the development of the Earth, and manifested itself in the form of major mountain-building movements that were repeated many times in the geological history of the development of our planet.

The sharp change in the organic world coincides with the largest mountain-building movements, which in their significance are revolutionary periods in the history of the development of the Earth. It turns out that the first mass extinction animals coincides with major mountain-building movements of the Caledonian folding, which ended at the Silurian-Devonian boundary. The second extinction - at the end of the Paleozoic - coincides with the last phases of the Hercynian folding, which ended at the boundary of the Late Permian and Mesozoic. The third era coincides with the ancient Cimmerian phase of Mesozoic folding, which occurred at the border of the Triassic and Jurassic periods. The fourth epoch is synchronous with the largest Laramian phase of Alpine folding. And finally, the fifth epoch, dated to the end of the Paleogene, coincides with the so-called Sava phases of Alpine tectogenesis.

The periods of these mountain-building movements were periods of very strong changes in physiographic conditions. These movements had a very significant impact not only on the distribution of land and ancient seas, but also on changes in the topography of ancient continents and the depth of the seas. They sometimes caused sudden changes in climate and environment and sharply disrupted the environment to which organisms had adapted. The new environment necessitated the adaptation of organisms to the new environment. Some organisms quickly adapted to the new environment and withstood the struggle for existence. Other animals, especially those with pronounced specialization, were unable to quickly adapt to the new conditions of existence, could not withstand competition with other species of animals and completely died out. Extinction of the same groups or species of animals developed in different parts ancient continents and seas did not happen simultaneously. First, there was a significant reduction in the number of representatives of a certain group of animals, and then a reduction in the areas of distribution and, finally, widespread extinction of the group.

The extinction of some animal species is closely related to the development of other, more advanced forms. Throughout geological time, continuous natural selection has been observed among the organic world.

The coincidence of periods of intense mountain-building movements with eras of extinction and renewal of the organic world is far from accidental, but has a completely natural character in the history of the development of the organic world. During periods of revolutions in the development of the organic world, large “leaps” are noted, the death of the old and the emergence of the new, represented by more advanced forms among animals and flora. During a period of relative tectonic calm, when there were no sharp changes in physical-geographical conditions and environment, gradual development and gradual evolution of the organic world was observed. During these periods, there is usually no sharp renewal of the organic world characteristic of revolutionary periods in the development of the Earth.

Currently, the Cenozoic era continues on Earth. This stage of the development of our planet is relatively short when compared with previous ones, for example, the Proterozoic or Archean. So far it is only 65.5 million years old.

Geological processes that occurred throughout the Cenozoic shaped modern look oceans and continents. The climate and, as a consequence, the flora in one or another part of the planet gradually changed. The previous era - the Mesozoic - ended with the so-called Cretaceous catastrophe, which led to the extinction of many animal species. Start new era was marked by the fact that empty ecological niches began to be filled again. The development of life in the Cenozoic era occurred rapidly both on land and in water and in the air. Mammals occupied a dominant position. Finally, human ancestors appeared. People turned out to be very “promising” creatures: despite repeated climate changes, they not only survived, but also evolved, settling throughout the planet. With time human activity became another factor in the transformation of the Earth.

Cenozoic era: periods

Previously, the Cenozoic (“era of new life”) was usually divided into two main periods: Tertiary and Quaternary. Now another classification is in use. The very first stage of the Cenozoic is the Paleogene (“ancient formation”). It began approximately 65.5 million years ago and lasted 42 million years. The Paleogene is divided into three subperiods (Paleocene, Eocene and Oligocene).

The next stage is Neogene (“new formation”). This era began 23 million years ago, and its duration was approximately 21 million years. The Neogene period is divided into Miocene and Pliocene. It is important to note that the emergence of human ancestors dates back to the end of the Pliocene (though at that time they did not even resemble modern people). Somewhere 2-1.8 million years ago, the Anthropocene, or Quaternary, period began. It continues to this day. Throughout the Anthropocene, human development has occurred (and continues to occur). The subperiods of this stage are the Pleistocene (glacial era) and Holocene (post-glacial era).

Climatic conditions of the Paleogene

The long period of the Paleogene opens the Cenozoic era. The climate of the Paleocene and Eocene was mild. Near the equator average temperature reached 28 °C. In the North Sea area the temperature was not much lower (22-26 °C).

On the territory of Spitsbergen and Greenland, evidence was found that plants characteristic of modern subtropics felt quite comfortable there. Traces of subtropical vegetation have also been found in Antarctica. There were no glaciers or icebergs in the Eocene. There were areas on Earth that did not lack moisture, regions with a variable-humid climate, and arid areas.

During the Oligocene period it became sharply colder. At the poles, the average temperature dropped to 5 °C. The formation of glaciers began, which later formed the Antarctic Ice Sheet.

Paleogene flora

The Cenozoic era is a time of widespread dominance of angiosperms and gymnosperms (conifers). The latter grew only in high latitudes. At the equator they prevailed rain forests, the basis of which were palm trees, ficuses and various representatives of sandalwood. The further from the sea, the drier the climate became: savannas and woodlands spread in the depths of the continents.

In the middle latitudes, moisture-loving tropical plants were widespread temperate climate(tree ferns, breadfruit ferns, sandalwood, banana trees). Closer to high latitudes species composition became completely different. These places are characterized by typical subtropical flora: myrtle, chestnut, laurel, cypress, oak, thuja, sequoia, araucaria. Plant life in the Cenozoic era (in particular, in the Paleogene era) it flourished even beyond the Arctic Circle: in the Arctic, Northern Europe and America, a predominance of coniferous-broad-leaved deciduous forests was noted. But the subtropical plants listed above were also found here. The polar night was not an obstacle to their growth and development.

Paleogene fauna

The Cenozoic era provided the fauna with a unique chance. The animal world has changed dramatically: dinosaurs have been replaced by primitive small mammals, living mainly in forests and swamps. There are fewer reptiles and amphibians. Various proboscis animals predominated, indicotherium (rhinoceros-like), tapiro- and pig-like.

As a rule, many of them were adapted to spend part of their time in water. During the Paleogene period, the ancestors of horses, various rodents, and later predators (creodonts) also appeared. Toothless birds nest on the treetops, and predatory diatrymas live in the savannas - birds that cannot fly.

Great variety of insects. As for the marine fauna, cephalopods and bivalves, corals; Primitive crayfish and cetaceans appear. The ocean at this time belongs to bony fish.

Neogene climate

The Cenozoic era continues. The climate during the Neogene era remains relatively warm and quite humid. But the cooling that began in the Oligocene makes its own adjustments: glaciers no longer melt, humidity drops, and the climate becomes more continental. By the end of the Neogene, zonation approached modern ones (the same can be said about the outlines of oceans and continents, as well as about the topography of the earth's surface). The Pliocene marked the beginning of another cold snap.

Neogene, Cenozoic era: plants

At the equator and tropical zones either savannas or rainforests still predominate. Temperate and high latitudes boasted the greatest diversity of flora: deciduous forests, mainly evergreens, were common here. As the air became drier, new species appeared, from which the modern flora of the Mediterranean gradually developed (olives, plane trees, Walnut, boxwood, southern pine and cedar). In the north, evergreens no longer survived. But coniferous-deciduous forests demonstrated a wealth of species - from sequoia to chestnut. At the end of the Neogene, landscape forms such as taiga, tundra and forest-steppe appeared. This again was due to the colder weather. North America and Northern Eurasia became taiga regions. In temperate latitudes with an arid climate, steppes formed. Where there used to be savannas, semi-deserts and deserts arose.

Neogene fauna

It would seem that the Cenozoic era is not so long (in comparison with others): the flora and fauna, however, managed to change greatly since the beginning of the Paleogene. Placentals became the dominant mammals. First, the anchytherium fauna developed, and then the hipparion fauna. Both are named after characteristic representatives. Anchytherium is the ancestor of the horse, a small animal with three toes on each limb. Hipparion is, in fact, a horse, but also three-toed. One should not think that the indicated fauna included only relatives of horses and simply ungulates (deer, giraffes, camels, pigs). In fact, among their representatives there were predators (hyenas, lions), and rodents, and even ostriches: life in the Cenozoic era was distinguished by fantastic diversity.

The spread of the mentioned animals was facilitated by an increase in the area of ​​savannas and steppes.

At the end of the Neogene, human ancestors appeared in the forests.

Anthropocene climate

This period is characterized by alternating glaciations and warming periods. When the glaciers advanced, their lower boundaries reached 40 degrees northern latitude. The largest glaciers of that time were concentrated in Scandinavia, the Alps, North America, Eastern Siberia, in the Subpolar and Northern Urals.

In parallel with the glaciations, the sea advanced onto the land, although not as powerful as in the Paleogene. The interglacial periods were characterized by a mild climate and regression (drying of the seas). Now the next interglacial period is underway, which should end no later than in 1000 years. After it, another glaciation will occur, which will last about 20 thousand years. But it is unknown whether this will actually happen, since human intervention in natural processes triggered climate warming. It's time to think about whether the Cenozoic era will end in a global environmental catastrophe?

Flora and fauna of the anthropogene

The advance of glaciers forced heat-loving plants to move south. True, mountain ranges prevented this. As a result, many species have not survived to this day. During the glaciations, there were three main types of landscapes: taiga, tundra and forest-steppe with their characteristic plants. Tropical and subtropical zones narrowed and shifted greatly, but were still preserved. During interglacial periods, broad-leaved forests predominated on Earth.

As for the fauna, the primacy still belonged (and belongs) to mammals. Massive, furry animals (mammoths, woolly rhinoceroses, megaloceros) became business card ice ages. Along with them there were bears, wolves, deer, and lynxes. All animals were forced to migrate as a result of cold weather and warming temperatures. The primitive and unadapted died out.

Primates also continued their development. The improvement of the hunting skills of human ancestors can explain the extinction of a number of game animals: giant sloths, North American horses, mammoths.

Results

It is unknown when the Cenozoic era will end, the periods of which we discussed above. Sixty-five million years is quite a bit by the standards of the Universe. However, during this time continents, oceans and mountain ranges. Many species of plants and animals became extinct or evolved under the pressure of circumstances. Mammals took the place of dinosaurs. And the most promising of mammals turned out to be man, and the last period of the Cenozoic - the Anthropocene - is associated mainly with human activity. It is possible that it depends on us how and when the Cenozoic era - the most dynamic and short of earthly eras - will end.

The Cenozoic era (“the era of new life”) began 66 million years ago and continues to this day.

This era is the period immediately following Mesozoic era. There is an assumption that it originates between the Melio- and Paleogene.

Just at this time, the second mass extinction of animals and plants was observed due to an unknown catastrophic phenomenon (according to one version, a meteorite fall).

Periods of the Cenozoic era

• Paleogene (ancient). Duration – 42 million years. Epochs - Paleocene (66 million - 56 million years ago), Eocene (56 million - 34 million years ago), Oligocene (34 million - 23 million years ago)
• Neogene (new). Duration – 21 million years. Epochs - Miocene (23 million - 5 million years ago), Pliocene (5 million - 2.6 million years ago)
• Quaternary (Anthropogenic). It still lasts. Epochs - Pleistocene (2.6 million - 12 thousand years ago), Holocene (12 thousand years ago until today).

Processes of the Cenozoic era

• Alpine tectogenesis, also called neotectonic, begins
• Mountains are forming Mediterranean Sea ridges and islands along the Pacific coast
• Block movements occurred in areas formed in previous periods
• The climate is changing and becoming more severe
• Deposits of many minerals are being formed - from gas and oil to gold and platinum.

Characteristics of the Cenozoic era

• At the very beginning of the Cenozoic era, there were two zones of geosynclinal folding - Mediterranean and Pacific, within which sedimentary layers were deposited.
• The Gondwana continental massif is breaking up.
• The North American continent and the Eurasian continent stand out.
• In the middle of the Paleogene, the Tethys Ocean extended to part of modern Europe, Siberia, Central Asia, Arabian Peninsula and African continent.
• In the late Paleogene, the sea leaves these platforms.

Life of the Cenozoic era

After the mass extinction of various species, life on Earth has changed dramatically. Mammals take the place of lizards. Warm-blooded mammals showed better adaptability to Cenozoic conditions. Arises new form life - a reasonable person.

Plants of the Cenozoic era

At high latitudes, angiosperms and conifers begin to predominate. The equator area was covered with rain wet forests(palm trees, sandalwood, ficus). Savannas and sparse forests were common in the interior of the continental zones. At mid-latitudes, tropical plants grew - breadfruit trees, tree ferns, banana trees, sandalwood.

The Arctic was covered with broad-leaved and coniferous trees. In the Neogene, the flora of the modern Mediterranean Sea begins to develop. In the north there were almost no evergreen plants. There are taiga, tundra and forest-steppe zone. In place of savannas, deserts or semi-deserts appear.

Animals of the Cenozoic era

At the beginning of the Cenozoic era, the following prevailed:

• Small mammals
• Proboscis
• Pig-like
• Indicotherium
• Horse Ancestors

Diatrima birds lived in the savannas - predators that could not fly. In the Neogene, lions and hyenas spread. Main mammals:

Chiropterans, rodents, monkeys, cetaceans, etc.

The largest are rhinoceroses, saber tooth tigers, Dinotherium and Mastodon. Placental mammals begin to dominate. Periodic periods of cooling and glaciation lead to many species becoming extinct.

Aromorphoses of the Cenozoic era

• Enlargement of the brain in a human ancestor (epimorphosis);
• Formation of a new geological shell of the earth - the noosphere;
• Distribution of angiosperms;
• Active development of invertebrates. Insects develop a tracheal system, a covering of chitin, a central nervous system, unconditioned reflexes develop;
• Evolution of the circulatory system in vertebrates.

Climate of the Cenozoic era

The climatic conditions of the Paleocene and Eocene were quite mild. In the equator zone, the average air temperature is about 28 0 C. At the latitude of the North Sea - about 22-26 0 C. In the area of ​​​​the modern northern islands, the vegetation corresponded to modern subtropics. Remains of the same type of flora have been found in Antarctica.

A sharp cooling occurred during the Oligocene period. In the area of ​​the poles, the air temperature dropped to +5 0 C. Signs of glaciation began to appear. Later, the Antarctic ice sheet appeared. In the Neogene climatic conditions were warm and humid. A zoning appears that resembles the modern one.

• In the Cenozoic era, primates and the first man appear;
• The most last glaciation it was 20,000 years ago, that is, relatively recently. The total area of ​​glaciers was more than 23 million km 2, and the thickness of the ice was almost 1.5 km;
• Many species of fauna and flora at the beginning and middle of the Cenozoic era are the ancestors of modern ones. At the end of the period, the outlines of the oceans and continents become similar to modern ones.

Results

Continents take on a modern look. The animal and plant world familiar to modern understanding is being formed. Dinosaurs completely disappear. Mammals (placentals) develop and angiosperms spread. Animals develop a central nervous system. Alpine folding begins to form and major mineral deposits appear.