Division of geological processes into endogenous and exogenous.

Endogenous processes: volcanism and seismic phenomena.

Seismic phenomena: causes and main parameters of earthquakes. Seismic zoning for construction.

Exogenous geological processes: weathering, wind activity, surface flowing water activity, sea and ocean activity, glacial activity, permafrost processes.

Human activity as a geological factor: mining, construction (urban, road, hydraulic).

Guidelines

When studying seismic phenomena, it is necessary to understand the mechanism of earthquakes, the concepts of “hypocenter” and “epicenter”, know the main types of waves and the classification of earthquakes by depth and strength. Exogenous processes manifest themselves in the smoothing of the earth's surface by the movement of rocks from convex to concave landforms. In this case, the rocks are subjected to triple influence:

destruction;

transfer;

deposition, accumulation and compaction.

The student needs to understand the essence of each of the exogenous geological processes. Special attention should be given to such concepts as erosion, eluvium, colluvium, proluvium, alluvium, moraine.

Seismic phenomena in geology are classified as internal endogenous processes. These are vibrations of elastic waves in the earth's crust. The point of origin of earthquakes, located at a depth from the surface, is called the earthquake source or hypocenter, and the point lying above it is called the epicenter. The most destructive earthquake sources are those that lie shallow (0-10 km). Destructions are associated with the propagation of seismic waves. Longitudinal waves propagate from the hypocenter at speeds of up to 4-5 km/s, and transverse waves travel perpendicular to them. Their speed is about 2 km/s. And surface waves arise on the surface - up to 500 m/s. The complex of these waves causes seismic deformations - cracks in the earth's crust, stepwise subsidence, swelling and displacement of soil: collapses, screes, landslides. In built-up areas - destruction of buildings and structures. The strength of earthquakes is characterized by points on the Richter scale (12 points).

Areas where earthquakes of magnitude 6 or more are expected are called earthquake-prone. Construction in these areas is carried out taking into account seismicity, i.e. the terrain, the presence of dislocations of layers, the presence of groundwater and its proximity to the surface, the possibility of landslides, landslides, screes, etc. are taken into account. At the same time, the rigidity of structures, the number of storeys, and the massiveness of buildings and structures are taken into account.

Endogenous processes also include volcanism and seismic phenomena. The appearance of volcanism is one of the most important geological processes of great importance in the history of the development of the earth's crust. Not a single area on earth was formed without the participation of volcanism. An earthquake is a special type of movement of the crustal plates of the lithosphere. They are expressed in wave, elastic vibrations and cause stable deformations of the earth's crust. By their nature, earthquakes can be denudation, volcanic, tectonic and man-made. Denudation earthquakes occur as a result of shock due to the collapse of a rock mass. Volcanic earthquakes can occur when a volcano erupts. Tectonic earthquakes are a consequence of tectonic processes occurring in the thickness of the earth's crust.

Exogenous processes include geological processes:

– Weathering is the change and destruction of rocks on the surface of the earth under the influence of sharp fluctuations in air temperature, freezing water, carbon dioxide, oxygen and organisms in the voids and cracks of rocks. In this case, processes of a physical, chemical and biological nature take place.

As a result of the weathering process, a completely special mineral formation is formed. Weathering crust is the upper (subsoil) part of the lithosphere within continents.

The technological activity of wind on continents consists of the destruction of rocks, the transfer and deposition (accumulation) of destruction products.

The destructive activity of wind consists of deflation - the blowing and dispersal of such rock particles, and corrosion - the mechanical processing of exposed rock surfaces with the help of solid particles carried by it.

Geological activity of seas, lakes and swamps. Marine imagery (the destructive effect of sea waves).

Glacier activity.

Human activity as a geological factor.

Types of weathering.

The weathering process occurs with the simultaneous participation of many agents, but their roles are far from equal. Based on the intensity of the impact of certain weathering agents and the nature of changes in rocks, it is customary to distinguish three types of weathering: physical, chemical and biological (organic).

Physical weathering is expressed mainly in the mechanical crushing of rocks without significantly changing them mineral composition. Rocks are crushed as a result of temperature fluctuations, freezing of water, mechanical force of the wind and impacts of grains of sand carried by the wind, crystallization of salts in capillaries, pressure that occurs during the growth of plant roots, etc. Temperature phenomena play a large role in this destruction. Under the conditions of the earth's surface, especially in deserts, daily temperature fluctuations are quite significant. Thus, in summer, during the daytime, rocks heat up to + 80 °C, and at night their temperature drops to + 20 °C. In addition to alternating heating and cooling, uneven heating of rocks also has a destructive effect, which is associated with different thermal properties, color and size of the minerals that make up the rocks. At the contacts of individual minerals, microcracks form and the rock becomes unstable. e The foam breaks up into separate blocks and fragments of various shapes.

Chemical weathering is expressed in the destruction of rocks through dissolution and changes in their composition. The most active chemical reagents in this process are water, oxygen, carbon dioxide and organic acids.

The simplest type of chemical weathering is dissolution in water. Rock salt and gypsum dissolve easily. The hydration process has a destructive effect. An example is the transition of anhydrite to gypsum. This process is accompanied by a sharp increase in volume (up to 50 - 60%), which causes destructive pressure of gypsum on the surrounding rocks. In the presence of water, oxidation also occurs. For example, the mineral pyrite, which is often present in various rocks, turns into iron oxide hydrate with the simultaneous formation of sulfuric acid, which, in turn, has a very destructive effect on minerals:

During chemical weathering, water containing carbon dioxide has a significant effect on rocks. As a result, feldspars turn into clay formations.

The intensity of chemical weathering depends on the area of ​​exposure to water and solutions, their temperature, as well as the degree of resistance of minerals to weathering agents; The most stable minerals are quartz, muscovite, and corundum; less stable - calcite, dolomite, etc. The intensity of chemical weathering is facilitated by the crushing of rocks as a result of mechanical weathering.

Chemical weathering is most important in warm and humid climates.

Biological (organic) weathering manifests itself in the destruction of rocks during the life of living organisms and plants. The rocks are crushed and are largely exposed to organic acids. Plants produce mechanical destruction with their root system. Tree roots are capable of splitting even strong rocks. There are known cases when the camel thorn plant grew through 20-centimeter reinforced concrete slabs. The roots of herbaceous vegetation easily overcome the layer of asphalt on city streets. Many living organisms, especially earth-diggers, actively destroy rocks. They create numerous passages and voids in the weathering crust, and even drill through hard rocks. The weathering of rocks is greatly influenced by numerous bacteria. In the process of their life, they absorb some substances and release others. Their impact is especially strong in the soil zone. Certain types of bacteria extract carbon from carbonates, destroy silicates, create an accumulation of iron ores, etc. Plants and animals, especially microorganisms (bacteria, microbes, etc.) and lower plants (algae, mosses, lichens), secrete various acids and juices, which, in turn, very actively interact with rock minerals, destroy them, and form new mineral formations.

Weathering deposits remain in place. Their formations are called eluvial and are designated by the index “e”.

All processes associated with the geological work of wind are called aeolian. The transfer of particles by wind occurs in suspended

condition or by rolling depending on wind speed and particle size.

When wind speed decreases and other favorable conditions occur, transported material is deposited. This is how wind-driven (eolian) deposits of sands (deserts) and loess are formed.

For construction has great importance sand hardness. On this basis, sand accumulations are divided into mobile (dunes and dunes) and fixed (ridges, hummocks) sands.

Loess deposits are characterized by silty clay particles arranged in layers of high porosity. In this regard, when soaked, such soils are deformed vertically even from their own weight, especially under the load from buildings and structures. These soils are called subsidence soils. Construction is carried out with preliminary compaction of these soils using various methods.

Wind deposits are aeolian and are designated by the index “L”.

Water flows from rain and snow melt wash away eluvial deposits, carry them along slopes to slopes, in particular, to the slopes of river valleys, and deposit them at the foot of these slopes. As a rule, such deposits are young in age, uncompacted, highly porous, most often represented by loams. Such loams are called loess-like because of their porosity and ability to sharply deform vertically when soaked.

The deposits are called colluvial and are designated by the index “d”.

The soil carried away by water flows, ending up in rivers, is carried by the energy of moving water. In this case, soil particles are transported in a suspended state, in a dissolved state, by dragging along the bottom. The process of particles carried by it falling out of water is called sedimentation, and their accumulation is called accumulation. The deposits formed in this case are called alluvium - river deposits (indicated by the index "a"). Floodplain alluvium is deposited during floods on floodplain terraces. Since the flow rate of water on floodplains is lower than in channels, floodplain waters usually contain smaller rock particles than channel waters. Floodplain alluvium is characterized by thin, almost horizontal layering, heterogeneity of granulometric composition and low thickness of layers with characteristic lens-shaped pinching out. There may be breaks in the accumulation of floodplain alluvium, and humus-containing soils are formed on floodplains. Channel alluvium is deposited in river beds after flood waters recede. The largest rock particles, carried into the river bed during a flood, are deposited after the waters recede. Channel alluvium, as well as floodplain alluvium, is characterized by horizontal or inclined layering, low layer thickness and good sorting of the material. Deltaic alluvium is deposited at the mouths of rivers as they flow into seas and lakes. Flowing into a water basin that does not have a current, the river’s water loses speed, and all the brought debris settles to the bottom. It is deposited on the coastal slope of the bottom in slightly inclined layers, gradually thinning towards the basin. All sand and clay fractions are found in delta alluvium deposits. The given characteristics of floodplain, channel and deltaic alluvium and the conditions of its formation are typical for lowland rivers. The formation of alluvium in mountain rivers has its own characteristics. Here it is not sediments that predominate, but erosion. Alluvial deposits of mountain rivers should practically be considered incompressible.

Delta alluvium has a large area distribution. Its thickness is significant, up to hundreds of meters in some rivers. Clastic, chemical and organic sediments take part in the structure of deltaic alluvium. The alluvium of the terraces participates in the structure of the accumulating and basement terraces. It consists of channel and floodplain deposits.

Within the oxbow lakes developed in the floodplains of old rivers, oxbow alluvium accumulates, consisting of soft organic silts mixed with floodplain sandy-loamy sediments. Peat deposits accumulate in swampy oxbow lakes. The oxbow alluvium occurs in the form of lenses among the floodplain alluvium.

Most rivers carry destroyed rock material to the sea or ocean, where a tremendous accumulation of sediment occurs on the ocean shelf and at the bottom. In addition, the sea and ocean in the coastal zone carry out destructive work with wave energy, transport destroyed material, segregate it by size and then deposit it at various depths. Sediment index – “m”.

Glaciers also play a significant role in the geological processes of external geodynamics.

Geological evidence suggests that in ancient times the glaciation of the earth was significant.

Currently, ice covers 10% of the land surface, 98.5% of the glacial surface is in the polar regions and only 1.5% is in high mountains. There are three types of glaciers: mountain, plateau and continental.

Mountain glaciers form high in the mountains and are located either on the peaks or in gorges, depressions, and various depressions. There are such glaciers in the Caucasus, the Urals, etc.

Ice is formed due to the recrystallization of snow. It has the ability to flow plastically, forming flows in the form of tongues. The movement of glaciers along slopes is limited by the altitude where solar heat is sufficient to completely melt the ice.

Plateau glaciers form in flat-topped mountains. The ice lies in an undivided continuous mass. Glaciers in the form of tongues descend from it through the gorges. This type of glacier, in particular, is now located on the Scandinavian Peninsula.

Continental glaciers are common in Greenland, Spitsbergen, Antarctica and other places where the modern era of glaciation is currently taking place. The ice lies in a continuous layer, thousands of meters thick.

The geological activity of ice is great and is determined mainly by its movement, despite the fact that the speed of ice flow is approximately 10,000 times slower than water in rivers under the same conditions.

As it moves, the ice abrades and plows the surface of the earth, creating depressions, ruts, and furrows. This destructive work is performed under the influence of the gravity of the ice.

Moving along gorges or any other inclined plane, glaciers capture food by freezing it into ice. The presence of cracks favors the penetration of debris into and into the lower part of the glaciers. Thus, the debris moves with the glacier. When ice melts, all the debris is deposited and glacial deposits of significant thickness are formed. Clastic material that is in motion or has already been deposited is called "moraines." Glacial deposits sometimes form ellipsoidal drumlin hills several tens of meters high, consisting of bottom moraine deposits. They consist mainly of moraine clays with boulders. Sediments are called glacial and are designated by the index “g”.

When the glacier melts, constant flows of meltwater are formed, which erode the bottom and terminal moraines. Water picks up material from eroded moraines, carries it outside the glacier and deposits it in a certain sequence. Such fluvioglacial deposits are called fluvioglacial – index “fg”.

Fluvioglacial deposits are characterized by comparative sorting and layering. They are usually represented by layers of sand, gravel, pebbles, as well as clays and mantle loams, the thickness of which reaches many meters. Fluvioglacial deposits create characteristic landforms:

1. Ozy - accumulation of clastic material (sand, gravel) in the form of high narrow shafts, the length of which ranges from hundreds of meters to tens of kilometers, height 5-10 meters.

2. Kamy - randomly scattered hills, consisting of layered sorted sands, sandy loams with an admixture of gravel and layers of clay.

3. Outwash fields are wide, gently undulating plains located beyond the edge of terminal moraines, which include layered sands, gravel and pebbles.

In place of the melted glacier, depressions remain, which become the bed of lakes and swamps. The geological activity of lakes consists of the accumulation of sediments from solid particles, most often small fractions brought by streams, and sediments together with organic matter. Such deposits are called lacustrine and are designated by the index “”.

Permafrost geological processes consist of seasonal freezing of the upper layers of soil in winter and thawing in summer. This causes heaving and subsidence of the soil. In construction, the standard freezing depth is taken into account, which is calculated as average value over the past 10 years, since the laying of foundations is carried out below the freezing depth.

In conditions where the average annual temperature is negative, permafrost is formed in the soil. In permafrost areas, the deformation of buildings and structures is associated with soil thawing, since its physical condition is disrupted due to the opening of foundation pits. Therefore, construction on permafrost soils is carried out according to three principles:

Without taking into account the frozen state (with a rocky foundation);

While maintaining the frozen state, due to thermal insulation;

With the thawing of frozen soils and their subsequent strengthening or replacement with others, for example, crushed stone.

As already noted, geological processes are usually divided into endogenous (deep) and exogenous (surface).

Endogenous processes include tectonic movements, seismic processes, magmatism, volcanism and metamorphism. These issues were discussed earlier in paragraphs 2.1, 2.3, 3.3, 3.7.

The list of exogenous geological processes is much longer. These include weathering, processes associated with the geological activity of underground and surface flowing waters, seas and lakes, with the activity of wind and glaciers, living organisms, humans, slopes and many other processes. Some of them were called engineering-geological processes. These are processes associated with human activity, as well as natural processes that actively destroy environment, negatively affecting construction and already constructed structures (Karpenko, Drozdov, Lomakin, 2014).

Endogenous geological processes

Endogenous processes include tectonic movements and seismic processes, magmatism, volcanism and metamorphism.

Tectonic movements and seismic phenomena are discussed in paragraphs 2.1 and 2.3. Tectonic movements are horizontal (tangential, folded) and vertical (epeirogenic, faulty).

Horizontal movements last for many millions and billions of years and occur over many thousands of kilometers - oceans and continents move. In the Archean and Proterozoic, all modern continents represented a single area - Pangea, located in the Southern Hemisphere. Then it split first into two parts, and then into six. Back in the Mesozoic (200 million years ago), Africa was separated from Eurasia by the Tethys Ocean. Its remains are the Mediterranean Sea.

The very fact of such large-scale horizontal movements is at first difficult to believe, but among geologists it is considered indisputably proven. The mechanism responsible for horizontal movements remains unclear. It is assumed that its source is the convective movement of matter in the asthenosphere - in the subcrustal volume of the upper mantle, while geophysical data indicate this matter as solid.

Horizontal tectonic movements perform enormous geological work. They crush rock layers into folds and force them to rise in relief high mountains or sink deep down, forming oceanic depressions. They form faults in the earth's crust, many of which later turn into seas and lakes. Magma intrudes along fractures in the earth's crust and volcanoes form. Earthquakes are also caused by horizontal movements.

Vertical movements have a small amplitude - tens and several hundred meters, they constantly raise and lower the surface of the continents. As a result, on the same territory, either a shallow shelf sea or land - a lowland, a plain or a low plateau - is alternately formed.

The main result of vertical movements is the accumulation of sedimentary cover. At a time when a certain territory falls below ocean level, there is an intensive accumulation of sedimentary material brought by rivers from the surrounding land (see Fig. 2.6). Additional material gives by the sea itself due to the destruction of the coastline. The sediments deposited at the bottom gradually become compacted and turn to stone. After some time, this territory again experiences uplift and turns into land, on which marine sedimentary rocks lie horizontally in the section.

Seismic phenomena - These are earthquakes - instantaneous movements of the earth's surface caused by movements of masses of the earth's crust. The source of displacement is horizontal movements of the earth's crust, pushing, tangential, stretching (see Fig. 2.12). Earthquakes, as a rule, are confined to certain areas of the earth's crust - geosynclinal and folded belts. Earthquakes occur mainly at the boundaries of tectonic structures, where significant stresses accumulate, ready to be realized in the form of a seismic shock. These territories are called seismic zones; they usually coincide with areas of intense volcanic activity.

Several similar scales are used to assess the strength of earthquakes. The first was the Richter scale. In our country, the Medvedev scale, which was close to it, was used. Nowadays the magnitude scale is often used. Relative energy characteristics of the earthquake (magnitude M) is defined like this:

Where L - the maximum amplitude of displacement of soil particles at a distance of 100 km from the epicenter; L e - reference amplitude of a weak earthquake.

In real cases, the magnitude is 9.5 in very strong earthquakes.

Seismic impacts can have different manifestations on engineering facilities depending on the magnitude of the earthquakes.

The effects of earthquakes of varying magnitude are dangerous for all hydraulic structures, so it is necessary to pay attention to the seismic resistance of dam construction. Experience shows that hydraulic structures built without taking into account the seismic factor were often subject to partial or complete destruction.

During earthquakes, soil particles move in space along a complex trajectory, and inertial forces arise, the magnitude and direction of which changes sharply over time. In this case, the deformations of structures and their elements can be of a complex nature with a predominance of deformations of axial tension, compression, bending, shear and torsion, which act dynamically, leading to wave and oscillatory movements of the entire structure as a whole. In Fig. Figure 4.7 shows serious damage to the highway during an earthquake.

Rice. 4.7.

Earthquakes cause serious damage to buildings, which can result in large casualties. The different nature of the destruction, the intensity of which is estimated in the range from 6 to 12 points on the Medvedev-Sponeyer-Karnik scale, is shown in Fig. 4.8.

Rice. 4.8.

The largest seismic regions are the Pacific and Mediterranean belts. 68% of all earthquakes are confined to the first, and over 20% to the second. On the territory of Russia, seismic regions include: the Caucasus, the Baikal region, Southern Primorye, Sakhalin, and the Kuril Islands.

Currently, the technogenic impact on the geological environment has reached such strength that earthquakes provoked by human activity have become possible.

The concept of “induced seismicity” includes both excited and initiated seismic phenomena. The main man-made causes are those that create excess load or, conversely, lack of pressure. The former are especially characterized by large reservoirs, the creation of which provokes the likelihood of an excited earthquake.

Magmatism and volcanism are a set of geological processes that are caused by the movement of magma from the bowels of the Earth. Magma is a natural high-temperature, straightened, viscous substance of the earth's crust, located mainly in the asthenosphere and upper mantle. The main reason for the melting of matter and the emergence of magma chambers in the lithosphere is an increase in temperature, and the rise of magma and its breakthrough into overlying horizons occurs due to density inversion, at which centers of less dense and mobile melt are formed. The upward movement of magma occurs primarily along weakened tectonic zones - the boundaries of tectonic structures, faults, and fold axes.

Magma originates at various depths and, rising upward, heats and melts rocks, along which its movement occurs. Depending on the nature of the movement of magma, deep (intrusive) magmatism and eruptive (effusive) magmatism are distinguished (Fig. 2.7).

From point of view chemical composition magma is a complex multicomponent system formed mainly by silica Si0 2 and substances chemically equivalent to silicates - Al, Na, K, Ca. Magma also contains volatile components (water vapor and gases H 2 S, H 2, HC1, C0 2), which are chemically very active, and their content at high pressure and high temperatures can reach 12%.

Penetrating into the thickness of rocks, magma breaks up into two phases - melt and volatile components, its temperature decreases, volatile components penetrate up the cracks of rocks, magma hardens and gives rise to igneous rocks (gabbro, granites, labradorites, etc.) . Magmatism processes play an extremely important role in the formation of the earth's crust, supplying it with material from the mantle and building it up. Igneous rocks make up the bulk of the earth's crust and occupy more than 90% of its volume.

Volcanism - this is a set of phenomena associated with the movement of magma and its outpouring to the surface. Volcanism is a natural geological process associated with the eruption (release) of solid and gaseous products of molten magma onto the Earth's surface, into the atmosphere and hydrosphere.

Currently, there are a total of about 500 active volcanoes on the continents and islands of the Earth. Terrestrial volcanoes form near deep-sea trenches - where an oceanic lithospheric plate moves under another lithospheric plate. The friction of lithospheric plates in these zones is accompanied by the release of significant heat, which ensures the melting of basalts and sedimentary rocks pulled together with the downward moving plate, where the temperature is about 1000°C. The molten masses are squeezed upward along with superheated water vapor released from the basalt rocks, and as a result, not only the formation of the continental crust occurs, but also the formation of volcanoes.

In the molten magma, water vapor and various gases (C0 2, CO, HC1, HF, S0 2, CH 4) are dissolved, which put pressure on the magma and, under pressure, lift it along the crater of the volcano. The main product of volcanic eruptions is effusive igneous rocks (rhyolites, andesites, basalts). In addition to them, gases and water vapor, as well as various loose solid products (volcanic ash, volcanic sand, volcanic bombs, which are gray-black in color), are emitted from volcanic vents.

Volcanic ash makes up the bulk of solid volcanic emissions and consists of small (from fractions to a millimeter) acute-angled particles consisting of volcanic glass and various minerals. The ash is often ejected along with small particles of pumice, which is a porous volcanic glass formed by the release of gases during the rapid solidification of acidic and intermediate lavas.

The volcanic ash cloud is a dangerous obstacle for flying aircraft. Sharp ash particles damage the engine's air supply system. The problem occurs even with a small concentration of ash.

Volcanic sand- These are lava particles ranging in size from 1 to 5 mm, almost always containing ash particles.

Volcanic bombs are the coarsest solid material that is ejected by volcanoes during eruptions. They can range from a few centimeters to a meter in diameter. These are pieces of erupted lava, ejected in a plastic state and taking on a variety of shapes (spherical, pear-shaped, cake-shaped, etc.).

The highest active stratovolcano in Europe is Mount Etna (3340 m), located on the east coast of Sicily and has many side craters and calderas through which lava eruptions and volcanic eruptions periodically occur. In Fig. 4.9 shows the dormant calderas of Mount Etna on the island. Sicily.

Rice. 4.9.

Products of volcanic origin on the extinct side craters of Etna volcano (Sicily) in the form of gray-black volcanic sand and basalt deposits are shown in Fig. 4.10.

Rice. 4.10.

The masses of ash that fell to the ground during the eruption, together with volcanic sand and pumice particles, become compacted over time and undergo cementation under the influence of various natural factors, resulting in the formation of rocks called volcanic tuffs.

Modern volcanoes are located on the globe in belts, along large faults and tectonically active regions - the Pacific, Mediterranean-Indonesian, Atlantic and Indian-African.

Every year, an average of 20-30 volcanic eruptions occur on earth, which, unfortunately, do not occur without human casualties. On the territory of Russia, the most tectonically mobile zone is the Kamchatka Peninsula and the Kuril Islands, where manifestations of volcanism are actively observed. Eruptions of the active Shiveluch volcano occur quite often; the last powerful eruption occurred in June 2013, resulting in the release of volcanic ash over 10 km.

An equally striking example of a powerful manifestation of volcanism is the Eyjafjallajökull volcano (Iceland), which began its eruption on April 14, 2010, which lasted several weeks (Fig. 4.11). The ash column of this volcano disrupted air traffic between Europe and America for several months.

Rice. 4.11.

Geysers are associated with the post-volcanic activity of modern volcanoes - springs that periodically emit fountains of hot water; fumaroles - small holes and cracks through which rise jets of water vapor and hot gases (H 2 0, HF, S0 2, C0 2, H 2 S, H 2, etc.) released from magma and from lava flows that have not yet cooled down and located in the crater, on the slopes and foothills of volcanoes.

Geysers are common in Kamchatka in the valley of the Geysernaya River, Iceland, New Zealand, USA (Yellowstone National Park), Chile.

Emissions of water vapor and gases in the side craters of Mount Etna were observed during 2012 and are shown in Fig. 4.12.

Rice. 4.12.

In Russia, the phenomena of post-volcanic activity are concentrated in the Valley of Geysers in Kamchatka (Fig. 4.13). Geysers periodically throw up columns of hot water (Fig. 4.14).

Rice. 4.13.

Rice. 4.14.

Volcanism also has positive features. The outpouring of magma from the crater of a volcano, the ejection of ash and other solid products of the eruption, fumarole jets - all this contributes to the removal of earth's surface various chemical elements located in the bowels of the earth. Therefore, areas of active tectonic activity abound in deposits of various minerals.

Metamorphism (from the Greek metamorphomai - undergoing change, transformation) is a process of deep change and recrystallization of the original rocks due to high temperatures, pressures and the transfer of matter by underground solutions and gases. The process proceeds gradually and in the initial stages we are talking only about some metamorphism of the original rock - about the appearance in it large quantity new minerals, partial changes in structure and texture. Further changes increase.

Any rock can be affected by metamorphism: sedimentary, metamorphic, igneous. Metamorphism processes occur at temperatures from 250 to 900°C. An increase in temperature by 10°C increases the rate of chemical reactions by 2 times, and by 100°C - by approximately 1000 times. Chemically active substances (water, carbon dioxide, hydrogen, chlorine compounds, sulfur compounds, etc.) are catalysts for various chemical reactions.

There are many types of metamorphism, the most common of which is regional. It develops at great depths throughout the territory globe and above all simply due to an increase in pressure and temperature there. The already mentioned gneisses, quartzites, marbles, and many crystalline schists are rocks of regional metamorphism.

The idea that the older the rock, the more metamorphosed it is, is only partly true; There is no such direct dependence. In nature, there are very ancient rocks that are completely unaffected by metamorphism, and, conversely, very young rocks that are highly metamorphosed. We can talk about another relationship (again, not always fulfilled): the deeper the rock lies, the more likely it is that it will be metamorphosed.

Why does metamorphism occur? Any chemical compounds (minerals) are stable within a fairly narrow range of temperatures and pressures. If conditions change, the original minerals will transform into others that suit the new conditions. The list of chemical elements with their percentages will remain the same.

Other types of metamorphism - metasomatosis, contact, hydrothermal, pneumatolytic, injection mainly associated with the interaction of intruding magma and its host rocks. There is an intensive exchange of chemical material due to the transfer of solutions and volatile components. The named varieties are distinguished depending on the prevailing conditions, metamorphic factors and newly formed rocks. The scope of development of the process is several kilometers to the sides of the magmatic melt. Dynamometamorphism develops as a result of increased pressure in tectonic zones.

MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION
INTERNATIONAL ACADEMY OF BUSINESS
AND NEW TECHNOLOGIES (MUBiNT)

Department of State Land Cadastre

by discipline: SOIL SCIENCE AND ENGINEERING GEOLOGY

Subject: Geological processes on earth according to the sources of their origin

Completed: student of group 134ZU-11

code no.
__________ Curly.Oksana. Dmitrievna.
(Full name, student signature)
"thirty" __ Martha ___ 2011

Supervisor: ____________________
(position, academic degree)

Bartsev A.V. ______ (full name, signature of the manager)

"___" _____________________ 200_g.

Yaroslavl 2011

Creative work assignment

Department state land cadastre
Specialty No.___________ land Registry
(name of specialty)
Discipline soil science and engineering geology
Student Curly.O.D groups 134ZU-11
(FULL NAME)

1. Topic of work

Geological processes on earth according to their sources

2. Text materials

Exercise. Creative work. Content. Introduction.
Main part
1. Geological processes
2. Basic geological processes on earth.
3. Division of geological processes.
4. Forecasting.
5. Conclusion.
List of used sources and literature.

3. Recommended reading
1.Theoretical foundations engineering geology. Geological foundations/Ed. acad. Sergeeva.E.M. – M.: Nedra, 1985, 332 pp., ill.
2. Geological Dictionary, T. 1. - M.: Nedra, 1978. – P. 403.
3. www GeoRus.
Date of assignment _____ 22.02.2011 _____ Work due date___ 11.05.2011 ____

Scientific supervisor _________________ Head. department ____________________

______________________________ ______________________________ ______
(full name, signature) (full name, signature)
Student _______________________
(signature)

Content
Introduction 4
1. Geological processes 5
2.Main geological processes on earth…………………………..……..6

3 . Division of geological processes into endogenous and exogenous.

10
4. Prediction of geological disasters. 12
5. Conclusion…………………………………………………………………….…13
Literature 14

INTRODUCTION
The surface of the Earth and its interior are constantly changing under the influence of a wide variety of forces and factors. The overwhelming majority of these processes of change proceed extremely slowly from a person’s point of view, imperceptible not only directly to his eye, but often imperceptible to many successive generations of people. However, it is precisely these slow processes over the course of millions and billions of years of the Earth’s history that lead to the most striking and major changes in its face and internal structure. They constitute the main content of the history of the Earth.
Among the geological processes, there are also those that manifest themselves very violently and lead to catastrophic consequences. These include powerful volcanic eruptions, destructive earthquakes, sudden mountain falls, etc. But these processes occur relatively rarely, cover relatively small areas and play a much smaller role in the history of the Earth.
To correctly understand the dynamics of the Earth and correctly interpret the patterns of its development, very subtle observation of slowly occurring geological processes is required. Their study constitutes the main content of dynamic geology.
Since the surface of the Earth. .. was covered with elevated areas that made up the continents, and depressions in which the waters that created the seas accumulated, geological figures... began their work on transforming this surface...
ACADEMICIAN V. A. OBRUCHEV
...endogenous geological processes are leading in the life of the Earth. They lay down the main forms of relief of the earth's surface, determine the manifestation of exogenous processes and, most importantly, determine the structure of both the earth's crust and the entire Earth as a whole.
ACADEMICIAN M. A. USOV

1.Geological processes.

The geological process is the interaction of a certain set of physical fields, in which there are more or less permanent components that are not of a permanent nature, operating during certain periods of geological time. The set of physical fields, during the interaction of which a new qualitative level is achieved (the level of the geological process), for the purpose of discussing methodological aspects, should be considered as a field of the geological process that determines the process of geological development (geological form of movement).
The geological process is associated with other processes (cosmic, atmospheric, hydrosphere, biological) by multi-stage interactions, often not fully understood from the point of view of cause-and-effect relationships. The spectrum of harmonic components, reflecting the periodic regime of celestial mechanics processes, as well as atmospheric, hydrosphere and biological ones, is inherited by the geological process and manifests itself in its product.
The importance of geological processes occurring in the near-surface part of the geological environment is extremely great. A.V. Sidorenko assessed it, taking into account human activity, as follows: “Nowadays the attention of mankind is drawn to the foundation of the cosmos. At the same time, geologists are planning to penetrate into the deep interior of the Earth to reach the so-called upper mantle. There is no doubt that knowledge of this level of the earth's crust will be of great importance for understanding many geological processes taking place in the earth's crust, and, first of all, the causes of its tectonic movements - the leading processes in the development of the Earth. However, we must not forget the enormous importance of those geological processes that occur directly on the surface and in the near-surface part of the Earth. The problem of studying these processes, especially considering human intervention in them, is not less value than the problem of the foundation of space, near-Earth space or the deep interior of the Earth.”
Geological processes in the upper part of the lithosphere represent a specific form of movement of matter with two sources of energy - external, from space, from the Sun, and internal, from the bowels of the Earth. Endo- and exogenous geological processes are characterized by unsteady regimes and inheritance in development. For relatively short time periods and for practical purposes and calculations, it is permissible to accept a quasi-stationary mode of development of processes with their corresponding characteristics.

2. Basic geological processes on earth:

Magmatism- a term that unites effusive (volcanism) and intrusive (plutonism ) processes in the development of folded and platform areas. Magmatism is understood as the totality of all geological processes, the driving force of which is magma and its derivatives.
Metamorphism ( Greek metamorphoomai - undergoing transformation, being transformed) - a process of solid-phase mineral and structural change rocks under the influence of temperature and pressure in the presence of a fluid.
Tectonics(from Greek ??????????, “construction”) - section geology , the subject of study of which is the structure (structure) of the Earth’s solid shell - earth's crust or (according to a number of authors) its tectonosphere (lithosphere + asthenosphere ), as well as the history of movements changing this structure. “Tectonics in design” - the form corresponds to the design (structure), manufacturing technology, and material. The connection between the most important characteristics of an industrial product - its structural basis and form in all its complex manifestations (plasticity, proportions, repetitions, character, etc.)
Exogenous processes- geological processes occurring on the surface of the Earth and in the uppermost parts of the earth’s crust (weathering, erosion, glacial activity, etc.); are caused mainly by the energy of solar radiation, gravity and the vital activity of organisms.
Hypergene process- proposed in the 20s of the twentieth century. academician A. E. Fersman the term “hypergene” for exogenous formations genetically related to processes weathering , that is, formed in an environment of low temperatures (+25° C) and pressure (1 atm.) with the active participation of water saturated with atmospheric gases, primarily oxygen. Naturally, the products of processes of crust formation and oxidation of mineral deposits, as well as soil complexes, were classified as hypergene. Lithogenic (sedimentary) formations, characterized by great specificity of sedimentation and diagenesis of sediments, remained representatives of “non-supergene” exogenesis.
Erosion(from lat. erosio - corrosion) - destruction rocks and soils surface water flows and wind, including the detachment and removal of fragments of material and their accompanying deposition.
Tectonic dislocations(from the late Latin word dislocatio - displacement, movement) - this is a violation of the bedding rocks under the influence tectonic processes. Tectonic dislocations are associated with changes in the distribution of matter ingravitational field Earth . They can occur both in the sedimentary shell and in deeper layers earth's crust.
Diapir(from Greek diapeiro - pierce, pierce) - dome- or shaft-shaped anticlinal folds with an intensely crumpled core, which can cut off the wings of the fold. Diapiric folds and domes usually arise due to the extrusion of highly plastic rocks from the lower horizons - salts, clays . When the pressure is unevenly distributed, the plastic material is pumped from one area to another, forming characteristic “blobs” - injection nuclei. In other cases, this material completely breaks through the overlying rocks and forms pierce cores, which, together with the anticlines that host them and create them, create a large family of diverse diapiric folds.

Salt tectonics

Salt diapir (light gray) in eroded core of the anticlinal fold.
A classic example of salt tectonics are the salt domes (white in the center) and fields (top left) in the Zagros Mountains
"Salt glacier "in the Zagros Mountains diapiric dome. A frequent phenomenon of the flow of viscoplastic salts, usually - halite , with salt tectonics.
Salt domes on the island of Mellwila, north Canada.
This is a common specific form of manifestation of folded dislocations of the sedimentary layer earth's crust . It is due to specialrheological propertiessalt strata (their relatively low density , but high, especially under high pressure conditions, plasticity).

Surge(English) surge - surge, syn. - glacier movement) - a sharp increase in movement speed (up to 300 m per day) glaciers . Surge is a regular phenomenon, representing one of the stages of pulsations (fast periodic oscillations) of glaciers of variousmorphogenetic types, mainly mountain-valley. Modern surgies and those caused by themnatural disastersknown in all areas of modern glaciations, including Antarctica and Greenland. Catastrophicglacial superfloods ( mudflows ), often occurring during outbursts of dammed lakes formed as a result of glacial surges, have repeatedly led and are leading to the death of a large number of people and other tragic consequences, and also greatly change relief and structure earth's surface.
Ske?blend(scableland, scableland) is a territory of glacial and periglacial zones that are exposed or have previously been exposed to multiple impacts of catastrophic superfloods (diluvial flows, floods, floodstreams, megafloods) fromglacier-dammed lakes, leaving the original erosional, evorsional and accumulative ( diluvium ) formations from which it is possible to reconstruct the history of scabland and give forecast . Scabland is an area dissected by parallel hollows, replete with teardrop-shaped hills, water basins and tracks cavitation ; geomorphological landscape created by a hydrospheric catastrophe.
Giant current ripples- active channel landforms up to 20 m high, formed in areas adjacent to thalweg of the pre-strezhnevs parts of the main diluvial valleys drain. The giant current ripple marks aremorphological and genetic a macro-analog of small sandy ripples in a current.
Diluvium(lat. diluvium - “flood, flood, flood”) - a genetic type of loose continental sediments resulting from accumulation processes precipitation in the drainage channels of catastrophic glacial superfloods fromglacier-dammed lakesafter glacial dam breaks in the recent geological past (the end of the lastice age, 11-15 thousand BC e.).
Spi?llway- path (channel) of a grandiose, usually catastrophic, discharge of water fromglacier-dammed lakes (diluvial flows) across low watersheds , pass saddles (through valleys), as well as through sub- and intraglacial cracks and channels into neighboring basins. Among the greatest spillways in the world isTurgaysky drainage channelGreat Siberian periglacial inland seas in the basin Atlantic, Kaz-Ket Spillway, connecting the Yenisei and Mansi Pleistocene new glacial-dammed seas.
Ice bodies- intermountain depressions and expansions river valleys that have been completely filled (or are currently being filled) glaciers mountain frame. They also represent a large element of meshglacial systems, which develops in conditions mountain basin relief , being isometric or slightly elongated in plan masses ice , filling these intermountain basins. Developed ice reservoirs are replenished with ice due to valley glaciers flowing into them; in addition, they can receive snowy nutrition and onto your own surface.
Diluvial terraces (shafts?)- these are forms diluvial relief , created in zones erosive shadows and reverse flows in the channels of catastrophic (diluvial) flows during discharges of giantglacier-dammed lakes. These terrace ramparts? especially expressive in the lower reaches of the river Chu?i and in the middle and lower reaches of the river Katu?ni , where they were first carefully studied by Russian and international scientific groups. They are characteristic morpholithological forms ske?blends .
Depression snow line (lat. depressio - depression, decrease) - its decrease due to climatic changes favorable for conservationglacier mass balance. Since mass balance is a direct function of accumulation and ablation , fluctuations in the height of the snow line reflect the cumulative effect of changes in temperature andatmospheric precipitation M. G. Grosvald believes that when talking about the depression of the snow line, one can also talk about the depression of the glacier feeding boundary and the glaciation boundary.
Marinism- direction in the natural sciences, mainly inQuaternary geology and paleogeography , denying the ancient ( Pleistocene) cover glaciation on plains and plateaus of temperate and subarctic zones.
Glacioisostasy(glacioisostatic fluctuations the earth's crust; Greek isos - equal, identical, stasis - state and lat. glacies - ice) - vertical and horizontal movements of the earth's surface in the territories of ancient and modern glaciation . The subsidence and uplift of often large areas of land and continental shelves are a consequence of a violationisostaticequilibrium of the earth's crust during the appearance and removal of glacial load.
Rafting- this is the spread of debris rocks , mainly moraines, or till (geology), floating glaciers and icebergs , much less often - sea and river ice, in the waters of the World Ocean, inland seas and periglacial lakes . Rafting is one of the main processes that are involved in the formationglacial-marine And glaciolacustrine sedimentsand also in transportation dropstones.
Dropstone(dropstone) - this is weak rounded rock fragment often large in size, several meters along long axes, as well as smaller fragments, up to pebbles and gravel , fallen from melting floating ice ( iceberg ) into thin-layered bottom sediments ocean, sea or lake . In the latter, in particular, predominantly mountain basin glacier-dammed lakes, dropstones precipitate in cases where the lake is emptied as a result of various mechanisms, the iceberg “sits” on the bottom (usually in shallow water, or on stranded).
Roundness- this is the degree of smoothness of the original edges of sedimentary (clastic) fragments rocks or minerals due to their breaking off, abrasion and, in general, destruction during transport or redeposition, mainly by fluid ( rivers ) and rough waters (lakes, seas in the coastal zone), by glaciers or wind , as well as under gravitational sliding, collapsing or shedding.
Erratic boulders, or glacial erratics ( lat. erraticus - wandering) - common name boulders, blocks , mainly massively crystalline, erupted or strongly metamorphosed rocks , differing inpetrographic compositionfrom the underlying substrate. This erratic material was transferred glacier or floating ice detached from the glacier ( iceberg ) at considerable distances from the bedrock outcrops of these parent rocks.

3. Division of geological processes into endogenous and exogenous.

Endogenous processes: volcanism and seismic phenomena.
Seismic phenomena: causes and main parameters of earthquakes. Seismic zoning for construction.
Exogenous geological processes: weathering, wind activity, surface flowing water activity, sea and ocean activity, glacial activity, permafrost processes.
Human activity as a geological factor: mining, construction (urban, road, hydraulic).
Seismic phenomena in geology are classified as internal endogenous processes. These are vibrations of elastic waves in the earth's crust. The point of origin of earthquakes, located at a depth from the surface, is called the earthquake source or hypocenter, and the point lying above it is called the epicenter. The most destructive earthquake sources are those that lie shallow (0-10 km). Destructions are associated with the propagation of seismic waves. Longitudinal waves propagate from the hypocenter at speeds of up to 4-5 km/s, and transverse waves travel perpendicular to them. Their speed is about 2 km/s. And surface waves arise on the surface - up to 500 m/s. The complex of these waves causes seismic deformations - cracks in the earth's crust, stepwise subsidence, swelling and displacement of soil: collapses, screes, landslides. In built-up areas - destruction of buildings and structures. The strength of earthquakes is characterized by points on the Richter scale (12 points).
Areas where earthquakes of magnitude 6 or more are expected are called earthquake-prone. Construction in these areas is carried out taking into account seismicity, i.e. the terrain, the presence of dislocations of layers, the presence of groundwater and its proximity to the surface, the possibility of landslides, landslides, screes, etc. are taken into account. At the same time, the rigidity of structures, the number of storeys, and the massiveness of buildings and structures are taken into account.
etc.................

External (exogenous) geological processes are powered by the energy of external sources and occur on the earth's surface or at shallow depths in the earth's crust. Main energy source – solar radiation. Consequently, exogenous processes depend on climate, vary by latitude, longitude and altitude, by time of year and day.

External geological processes are divided into two groups: weathering processes and the work of external dynamic agents. The latter include surface and underground waters, wind, and glaciers.

External processes change tectonic structures created by the internal forces of the Earth. Change is achieved by three types of work: destruction of rocks, transfer and accumulation (accumulation) of debris. Positive tectonic structures are destroyed: folded mountains, shields. This is due to gravity: the higher the territory, the greater the speed and strength of the external agent. The debris is carried down the slope to the lowest places on the earth's surface: intermountain and foothill troughs, lakes and, most importantly, seas. The influence of temperature is great - the distribution of water, winds, and glaciers depends on it.

External agents accumulate sedimentary rocks. The work of external agents simplifies the relief: high areas are lowered, debris accumulates at the foot - their surface rises. The destruction (smoothing) of the relief by external agents is called denudation.

Weathering– physical and chemical destruction of rocks by the atmosphere, water, and living organisms. Weathering is divided into physical, chemical and biological. They act together, manifesting themselves differently in specific conditions.

Physical weathering – mechanical crushing of rocks, forming angular fragments of different sizes: blocks, crushed stone, sand, dust. Physical weathering is divided into frost and temperature.

Frosty weathering - destruction of rocks by water freezing in cracks (when freezing, the volume of water increases by 10%). The process is active during frequent temperature transitions through 0 °C, therefore it is characteristic of moderate and high latitudes and high mountains.

Temperature(thermal) weathering– destruction of rocks by sudden temperature changes: rocks cannot withstand repeated expansion when heated and compression when cooled. This process is typical of hot deserts.

Chemical weathering– destruction of rocks by chemical reactions. The main factor is water containing dissolved gases and acids. Chemical weathering leads to either a change in composition or complete dissolution of rocks. Among the products, tiny clay particles occupy an important place. The greatest activity of processes is in the humid tropics.

Biological(organic) weathering – destruction of rocks by physical and chemical activity of organisms.

The main weathering factor is a zonally changing climate, so weathering processes are distributed zonally. In cold climates of high latitudes and arid deserts, physical weathering dominates. In temperate climates, physical and chemical weathering are approximately equivalent. In the humid and warm climate of low latitudes, chemical weathering predominates. Weathering processes form a layer of loose rocks on the surface - weathering crust.

The activity of external dynamic agents is regulated by kinetic energy: E = mv2/2. Therefore, the nature of the work performed (destruction, transfer or accumulation) depends more on the speed of movement of the geological agent than on its mass. Destruction and transport predominate at high speeds, accumulation begins with a decrease in speed. Large particles accumulate immediately, and as the speed decays, smaller ones accumulate.

Work of surface flowing waters includes the activities of permanent (rivers) and temporary watercourses.

Geological activity of rivers forms river valleys. river valley- a linear depression in the earth's surface created by a river. Composition of a river valley: bed, floodplain, slopes and above-floodplain terraces. Bed- the lowest part of a valley through which a river flows constantly or intermittently. Floodplain- the lower part of a river valley, flooded by the river during floods. Above the floodplain are the slopes of the valley. On the slopes there are steps stretched along the valley - above-floodplain terraces.

The processes of rivers, river sediments, and the landforms created by rivers are called alluvial.

The destructive work of water flows is called erosion. Erosion is carried out by the impacts of water jets, transported debris, and the dissolution of rocks by water. There are two types of erosion: bottom and lateral.

Donnaya(deep) erosion deepens the channel and river valley. It is caused by gravity and is most typical of mountain rivers and the upper reaches of lowland rivers. Mountain rivers have enormous energy, cut deeply into the earth's surface and create canyons– deep, narrow and long valleys with steep slopes. The greatest Grand Canyon on Earth was created by the Colorado River - the height of its walls exceeds 2000 m, the length is 320 km. If a river flows through rocks of different strengths, then the erosion rate is not the same, and steps appear in the riverbed. Falling from the steps, the water bubbles and foams. Low steps are called rapids, high ones - waterfalls. The highest waterfall on the planet - Angel (1054 m) - is located on the Churun ​​River (a tributary of the Orinoco River). One of the widest waterfalls is Niagara (Niagara River), divided by Goat Island into two parts, the total width of which is 1300 m. Bottom erosion becomes more active with lowering erosion basis– the level of the surface into which the stream flows (lakes, seas). As a result of increased erosion, the river deepens the valley and forms terraces above the floodplain. The terraces are numbered from bottom to top (from young to ancient).

Lateral erosion leads to erosion of the banks - the channel becomes winding. The main factor of lateral erosion is Coriolis acceleration, which is why in the Northern Hemisphere the right banks of rivers are steep and the left banks are flat. In the Southern Hemisphere it is the other way around. Lateral erosion is characteristic of lowland rivers. Loop-shaped bends in a river bed are called bends(meanders- after the Menderes River in western Turkey). Over time, the river breaks through an isthmus between neighboring bends. The water rushes into a straight and short section of the new channel, and the cut off bend turns into a lake. Lakes that arose on the site of an old riverbed are called old-fashioned.

The transport work of rivers is to transport debris. Solid drain rivers - a mass of debris carried out by a river over a year. The world leader in solid waste is the river. Yellow River.

The accumulative work of rivers is the accumulation of transported debris in the mouth and bed, and also, during floods, on the river floodplain.

Temporary watercourses occur during precipitation and snow melting. Their work is active on slopes composed of loose rocks and not covered with grass. Temporary streams on the plains form ravines– depressions with steep slopes devoid of vegetation and a narrow bottom. Gullies can branch out, taking on a tree-like shape. With the cessation of growth of the ravine, the slopes crumble, flatten, the bottom expands, vegetation develops: the ravine turns into beam– a hollow with gentle turf slopes and a flat bottom. In the mountains, temporary watercourses are exceptionally strong, tearing down and transporting huge volumes of rocks - forming mudflows(sat down). There are three types of mudflows: water-rock, mud, mud-stone.

Main type of geological work surface standing water (lakes, swamps, seas) - accumulation at the bottom of various particles settling from the water column. As a result, the reservoirs become shallow and disappear – the earth’s surface levels out. At the bottom lakes small particles of organic or mineral composition accumulate. Accumulates in humid climates clay, marl(mixture of clay and lime particles), sapropel(organo-mineral sludge). Lakes in dry areas accumulate salt(stone, potassium, mirabilite). IN swamps deposits are being formed peat, sometimes – stocks limonite(low-grade iron ore).

Geological work groundwater manifests itself in karst and landslide processes. Karst– dissolution of rocks by water with the formation of underground caves or craters on the surface. Karst conditions: precipitation and the spread of water-soluble rocks (limestone, salt, gypsum) on the surface (or at shallow depths). The most widespread is lime karst. The largest karst cave on Earth is Flint Mammoth in the eastern United States (more than 485 km long). Landslide– rapid sliding of slope deposits.

Landslides occur on slopes, the surface of which is composed of loose rocks, and deeper lies impermeable (waterproof) rocks. Heavy rains or meltwater impregnate loose rocks, the surface of the aquiclude becomes wetted and becomes slippery - the adhesion between the soils disappears, and the surface layers saturated with moisture are torn down.

Glaciers in the Quaternary period they occupied vast areas of the continents of the Northern Hemisphere. Therefore, traces of glaciers are common both in areas of modern glaciation (polar belts and highlands) and on the plains of temperate latitudes.

Destructive work is active when the glacier moves. A glacier, sliding down a mountain valley, tears off and carries away loose rocks. As a result, there are trough valleys(trogs) - deep valleys with steep rocky slopes and a flat bottom. After the glacier melts, the bottom of the trough can flood the sea - this is how fjords. With debris frozen into the bottom, the glacier scratches and polishes the ledges of hard rock, leaving behind a smoothed relief sheep's foreheads And curly rocks. Trough valleys, fjords, sheep's foreheads and curly rocks are most common in the polar regions: in Karelia, on the Scandinavian Peninsula. Rock fragments carried by a glacier are called moraine.

Accumulative operation is active when the glacier melts. The brought debris is accumulated by the glacier itself or its melt waters. Glaciers accumulate moraine deposits that have the appearance of steep hills in relief, accreted into ridges. The moraine material is not sorted: there are boulders, sands, and clays. Glacial meltwater accumulates water-glacial sediments composed of sorted (layered) fragments, mainly sands. Outside moraines, flows of glacial meltwater accumulate flow-glacial sediments composed of layered sands. In relief they create undulating plains called outwash. Also formed lacustrine-glacial sediments , composed of horizontally layered clays and creating flat plains in relief (Polotsk lowland).

The work of the wind, wind deposits and landforms are called aeolian. Aeolian processes are intense if the vegetation is sparse and there is loose dry sand and dust on the surface. Such conditions are typical of deserts, sandy shores of seas, large lakes and rivers.

The wind destroys in two ways: by blowing away fine earth and by abrading encountered obstacles with transported particles. Wind blowing – deflation– forms extensive depressions (blowing basins). Grinding rocks with transportable grains of sand – corrosion– creates rocks of bizarre shapes.

Wind accumulation forms sand hills with a gentle windward slope and a steep leeward one. There are two main types of aeolian hills: barchans and dunes. Dunes – sand hills shaped like a crescent, the ends of which are directed downwind. Dunes appear only in dry deserts, when the wind carries dry sand in one direction for a long time. Dunes also have the shape of a crescent, but the “horns” of the dunes face the direction from which the wind blows. Dunes appear only on coasts where groundwater is close.

Geological processes are divided into endogenous and exogenous.

Endogenous geological processes

Endogenous geological processes include magmatism, metamorphism, earthquakes, and tectonic disturbances.

Magmatism

Igneous rocks, formed from liquid melt - magma, play a huge role in the structure of the earth's crust. These rocks were formed in different ways. Large volumes of them froze at various depths, not reaching the surface, and had an impact strong impact on host rocks by high temperatures, hot solutions and gases. This is how intrusive bodies were formed. If magmatic melts erupted to the surface, volcanic eruptions occurred, which, depending on the composition of the magma, were calm or catastrophic. This type of magmatism is called effusive, which is not entirely accurate. Often, volcanic eruptions are explosive in nature, in which the magma does not pour out, but explodes and finely crushed crystals and frozen droplets of glass - raplava - fall onto the earth's surface. Such eruptions are called explosive. Therefore, when talking about magmatism, one should distinguish between intrusive processes associated with the formation and movement of magma below the earth's surface, and volcanic processes caused by the release of magma to the earth's surface. Both of these processes are inextricably linked, and the manifestation of one or the other of them depends on the depth and method of formation of magma, its temperature, the amount of dissolved gases, geological structure area, nature and speed of crustal movements, etc.

Both intrusive and volcanic rocks contain mineral deposits and, in addition, they are reliable indicators of the tectonic and paleogeographic conditions of the geological past, which allows us to reconstruct them.

Metamorphism

After formation, rocks can fall into a geological environment that will differ significantly from the environment in which the rock was formed and will be influenced by various endogenous forces: heat, pressure (load) of overlying strata, deep fluids, solutions and gases, water, hydrogen, carbon dioxide etc. The change in igneous and sedimentary rocks in the solid state under the influence of endogenous factors is called metamorphism.

All metamorphic processes can be divided into two groups. In one of them, the chemical composition of the metamorphosed rocks does not change, i.e. the transformation occurs isochemically. In the second group, a change in the composition of rocks is observed due to the introduction or removal of components. This process is called allochemical. Under the influence of metamorphism processes, recrystallization of the original rocks occurs, a change in the mineral and often chemical composition. Metamorphic processes can be of varying intensity, therefore, in nature, all postural transitions are observed from practically unchanged or weakly altered rocks, the primary texture, structure and composition of which have been preserved, to rocks that have been altered so strongly that it is impossible to restore their primary nature. Increased degree of metamorphism, i.e. An increase in temperature, pressure and fluid concentration leads to a change or disintegration of unstable minerals into more stable associations. When studying metamorphic rocks, it is necessary to restore their primary nature and conditions of formation, as well as to reconstruct the conditions of metamorphism - pressure, temperature and the role of volatile components. This makes it possible to understand the most powerful strata of Hedian, Archean and Proterozoic rocks, which mainly form the foundation of ancient platforms and correspond in the age interval to most of the history of the Earth - 2.5-4.6 billion years. These same rocks are associated with very important practically important metamorphogenic deposits containing iron ores, graphite, gold, uranium, copper, quartzite, marble, etc.

Earthquakes

More than 100,000 earthquakes are recorded on Earth every year. We don’t feel most of them at all, some respond only to the rattling of dishes in cabinets and the swaying of chandeliers, but others, fortunately much rarer, in the blink of an eye turn cities into piles of smoking rubble. On the coasts, the sea retreats, exposing the bottom, and then a giant wave hits the shore, sweeping away everything in its path, carrying the remains of buildings into the sea. Major earthquakes are accompanied by numerous casualties among the population, who die under the ruins of buildings, from fires, and finally, simply from the resulting panic. Earthquakes are a disaster, a catastrophe, therefore, enormous efforts are spent on predicting possible seismic shocks, on identifying earthquake-prone areas, on measures that are designed to make industrial and civil buildings earthquake-resistant.

Behind Lately catastrophic earthquakes occurred in Chile (1960), Alaska (1969), Guatemala (1976), China (1976), killing 100,000 people. Very strong earthquakes have been recorded on the territory of the USSR more than once: Andijan (1902), Kemin (1911), Khait (1949), Ashgabat (1929 and 1948), Tashkent (1966), Gazli (1970, 1976, 1984) and, finally, the terrible Spitak earthquake in Armenia (1988).

Any earthquake is a tectonic deformation of the earth's crust or upper mantle, occurring due to the fact that the accumulated stress at some point exceeded the strength of the rocks in a given place. The discharge of these stresses causes seismic vibrations in the form of waves, which, upon reaching the earth's surface, cause destruction.

The source, or hypocenter, of an earthquake is a certain volume of rocks, within which inelastic deformations occur and rock destruction occurs. Epicenter is the projection of the hypocenter onto the earth's surface. The distribution map of the epicenters of modern earthquakes clearly shows their connection with the periphery Pacific Ocean, the Mediterranean mobile belt (Alps, Carpathians, Caucasus, Himalayas), as well as with mid-ocean ridges in all oceans.

Tectonic disturbances

In most cases, sediments formed in lakes, seas and oceans have a primarily horizontal occurrence, which is often disturbed by tectonic movements, which leads to the formation of folds, on the one hand, and faults, on the other.

A fold is a bend in the layers. The core of the fold and its wings are distinguished. Folds are anticlinal and synclinal. The cores of anticlinal folds are composed of rocks of older layers, the cores of synclinal folds are composed of younger layers. The folds of the layers form fold locks.

Most often, folds are formed when continental plates shift, when unconsolidated horizontal layers are crushed between shifting cratons. In this case, linear folds with approximately identical locks of anticlinal and synclinal varieties are formed. Under the influence of predominantly vertical movements, brachyfolds are formed in mobile belts, where the shape of the locks of anticlinal and synclinal folds is different. Dome-shaped folds of an isometric shape with very flat wings are formed on the platforms.

Disruptive violations

A fault is the deformation of rock layers with a violation of their continuity, which occurs when the tensile strength of rocks is exceeded by tectonic stresses. In any fault, the plane of the fault or displacement plane and the wings of the fault are always distinguished, i.e. two blocks of rock on either side of the fault plane that have been displaced. The wing or block located above the displacement is called hanging, and below it is called recumbent. An important parameter of the rupture is its amplitude. The distance from the strata in the hanging wall to the same strata in the hanging wall is called the amplitude along the displacement. In addition, a stratigraphic amplitude is distinguished, which is measured normal to the bedding plane in any wing of the fracture before the projection of the formation; vertical amplitude - projection of the amplitude along the displacement onto the vertical plane; horizontal amplitude - projection of the amplitude along the displacement onto the horizontal plane. The position of the displacement in space is determined, like the orientation of any other plane, using the lines of incidence, strike and angle of incidence.

The main types of faults: fault (the fault plane is inclined towards the lowered wing, the fault angle is greater than 45 0), reverse fault (the fault plane is inclined towards the raised wing), thrust (reverse fault with the fault angle less than 45 0), shear (movement of the wings along the strike displacement), thrust (thrust with an almost horizontal position of the displacement), pull-apart (horizontal displacement of fault blocks in opposite directions), shear (horizontal displacement of fault blocks towards each other).

Displacement amplitudes reach 4000 km - during the moving apart (spreading) of continental plates. Approximately the same amplitudes were observed during shifts of continental plates, as a result of which ripples were formed with a displacement amplitude of hundreds of kilometers.

Exogenous processes

Exogenous processes include: weathering, geological activity of wind, surface flowing water, groundwater, glaciers, geological processes in areas of permafrost, geological activity of oceans and seas.

Weathering

Weathering is understood as a set of physical, chemical and biochemical processes of transformation of rocks and their constituent minerals in the near-surface part of the earth's crust. This transformation depends on many factors: temperature fluctuations, chemical effects of water and gases - carbon dioxide and oxygen, exposure organic matter, formed during the life of plants and animals and during their death and decomposition. The above indicates that weathering processes are closely related to the interaction of the near-surface part of the earth's crust with the atmosphere, hydrosphere and biosphere. The part of the earth's crust where the transformation of mineral matter occurs is called the weathering zone or the hypergenesis zone. Conventionally, two interrelated factors are distinguished: physical and chemical weathering.

Geological activity of wind

The geological activity of wind consists of the following types: deflation (blowing and fluttering), corrosion (grinding, scraping), transport and accumulation. All processes caused by wind activity, the relief forms and sediments they create are called aeolian.

Wind activity is most pronounced in deserts, which occupy about 20% of the surface of the continents, where strong winds are combined with a small amount of precipitation, sharp temperature fluctuations, and a lack of vegetation cover due to the arid climate.

Geological activity of surface flowing waters

Flowing water refers to all types of surface runoff on land, from streams that occur when rain falls and snow melts to the largest rivers. All water flowing over the surface of the Earth performs various types of work. It is well known that surface flowing water is one of the most important factors in the denudation of land and the transformation of the face of the Earth.

As in other exogenous processes, three components can be distinguished in the activity of flowing waters: destruction, transport and deposition, or accumulation, of transported material, ultimately at the first (at the foot of the mountains) and second (in river deltas) levels of accumulation. Based on the nature and results of activity, three types of surface water flow can be distinguished: flat, channelless slope flow, flow of temporary channel flows and flow of permanent watercourses - rivers.

Rock destruction occurs mainly in the mountains. On the plains, transport and accumulation predominate. Every year, rivers carry about 20 km 3 of sandy-clayey material into their mouths. The largest place of temporary accumulation of debris carried by rivers is the mouth of the Ganges and Brahmaputra rivers, about 2 km 3, or 10% of all transported and deposited material. This is due to the highest denudation mountain system- Himalayas.

Geological activity of groundwater

Groundwater includes all natural waters located under the surface of the Earth in a mobile state. Issues of the origin, movement, development and distribution of groundwater are the subject of study of a special branch of geological science - hydrogeology. Groundwater is closely related to the water of the atmosphere and the terrestrial hydrosphere - oceans, seas, lakes, rivers. IN natural conditions There is a continuous interaction of these waters, the so-called hydrological cycle.

One of the most important factors determining the conditional beginning of the cycle is the evaporation of water from the surface of the oceans and seas and the entry of moisture into the atmosphere. Under favorable conditions, atmospheric water condenses and falls as precipitation. The distribution of the latter can be represented by the following scheme: evaporation, surface runoff, infiltration, or seepage, underground runoff.

The water reservoir properties of rocks are determined by their porosity and fracturing. The highest water permeability is observed in pebbles, gravel, coarse sands, heavily karstified limestones and highly fractured rocks of various origins. Relatively weak permeability is observed in fine-grained sands and sandy loams, and even less in loess, light loams, and slightly fractured rocks. Almost impermeable (waterproof) are clays, heavy loams, cemented and other massive rocks with negligible fracturing.

Rocks contain different types of water:

1. Water in the form of steam.

2. Physically bound water, hygroscopic and film.

3. Free water, capillary and gravitational.

4. Water in a solid state.

5. Crystallization and chemically bound water.

In modern hydrogeological literature, they distinguish between different types groundwater to specific zones: aeration zone and saturation zone.

Soil water and perched water are formed in the aeration zone. In the saturation zone, waters are distinguished: groundwater, interstratal free-flow and interstratal pressure, or artesian.

Geological activity of glaciers

Glaciers are natural masses crystal ice, located on the Earth's surface as a result of the accumulation and subsequent transformation of solid atmospheric precipitation (snow). A necessary condition for the formation of glaciers is a combination of low temperatures with a large amount of solid precipitation, which occurs in cold countries at high latitudes and in the top parts of mountains.

There are three main types of glaciers: 1) continental, or cover, 2) mountain, 3) intermediate, or mixed. Classic examples of existing continental glaciers are the ice sheets of Antarctica and Greenland. Antarctica covers an area of ​​about 15 million km2, of which about 13.2 million km2 is covered with ice. The ice cover forms a huge plateau up to 4 km high.

During the Quaternary period, large parts of Europe and North America were also covered by continental ice sheets.

During their movement, glaciers destroy rocks, transport debris and accumulate them in the form of moraines. One of these terminal moraines is located near the Moscow State University beyond the Yauza River on the territory of Losiny Island.

Geological processes in areas of permafrost distribution

It is well known that the surface layers of soils and soils are subject to seasonal freezing in winter and thawing in spring and summer. The greatest freezing depth in the northern hemisphere is observed in the northern circumpolar regions, the smallest in the southern ones. This upper layer of periodic freezing and thawing is highly dynamic and is called the active layer. Below it, in vast areas of Northern Eurasia and North America, permafrost rocks (PFR) are developed. In Russia they occupy more than half the area.

The permafrost zone is called the frozen zone of the earth's crust or cryolithozone. Accordingly, the science that studies the permafrost zone and the processes associated with it is called geocryology or permafrost studies.

A number of geological processes are observed in the permafrost zone. Repeated ice wedges form in the northern geocryological zone. Their development is associated with frost cracks that form polygon systems. Frost heaving is characteristic of various areas of the permafrost zone. Injection heaving bumps are formed in a closed system. Slope processes include solifluction and kurums.

Geological activity of oceans and seas

The entire set of water spaces of oceans and seas, occupying 70.8% of the Earth's surface, is called the World Ocean, or oceanosphere. The World Ocean includes four oceans: the Pacific, Atlantic, Indian and Arctic, all marginal (Bering, Okhotsk, Japanese, etc.) and inland seas (Mediterranean, Black, Baltic, etc.).

The topography of the bottom of the oceans and seas includes a shelf, a continental slope, a bed of the World Ocean with uplifts (mid-ocean ridges, swells, volcanic islands and guyots) and deep-sea depressions (Tonga-Kermadec, Kuril-Kamchatka, Izu-Bonin, etc.).

In the World Ocean, at the foot of the continental slope, the main part of the clastic material formed during denudation is formed at the third level of sedimentation, part of the latter is carried by geostrophic currents along the bottom of the World Ocean. At depths of less than 4 km, carbonate silts are more often formed in the inner parts of the World Ocean, which subsequently turn into limestone. In the deep-sea parts of the oceans, diatomaceous and radiolarite oozes, as well as red deep-sea clays with cryoconite, are formed. Within the mid-ocean ridges, under the influence of black witches (black smokers), deposits of copper, base metals and gold are formed.