Relief erosion. Hazardous Geological Processes - Erosion

Geological environment. The geological environment will experience a man-caused impact both during the construction and operation of the gas pipeline. We should expect the activation of exogenous geological processes, such as subsidence and suffusion in loess rocks, the development of landslides on the mountainous section of the route, the manifestation of erosion processes, soil swelling. The above processes can Negative influence on the functioning of the GTS.[ ...]

Geological erosion is a slow process of washing off particles from the surface of the soil covered with natural vegetation. At the same time, the loss of soil is restored during soil formation, and in practice this erosion does no harm.[ ...]

Soil erosion is a natural process that depends on climate, topography and the nature of the soil itself. In the presence of a permanent and undisturbed vegetation cover, erosion proceeds more or less gradually and is balanced by soil-forming processes. In the absence of vegetation cover, erosion accelerates. Areas that, due to climatic or topographical conditions, do not have a permanent vegetation cover, as, for example, in the Grand Canyon, are subject to "geological" erosion. Erosion caused by tillage or overgrazing by livestock is intensified by the action of water in areas with a humid climate, and by wind in dry areas.[ ...]

The geological conditions that affect the development of erosion are mainly determined by the degree of resistance of soils and rocks to the eroding action of water and dispersal by the wind. Loess-like, deluvial-alluvial loams and loesses are quite easily eroded with the formation of steep walls in gullies and ravines, but mainly in the presence of sufficiently deep local erosion bases; at shallow bases of erosion, ravines, as a rule, do not form. In the case of thin loess-like loams and loess (about 3-4 m) and their underlying limestone, ravine erosion is absent due to the formation of "failures" in the rocks - "gullies" in the form of funnels (karst funnels), into which melt and rain water.[ ...]

Soil erosion without human intervention has existed and exists at the present time. It's called geological erosion. The concept of anthropogenic erosion is often unreasonably identified with the concept of accelerated erosion, and the concept of geological erosion with the concept of normal erosion. And if anthropogenic erosion is most often (but not always!) Accelerated, then geological erosion is not necessarily normal.[ ...]

Types of erosion. According to the rate of manifestation of erosion processes, normal, or geological, and accelerated, or anthropogenic, erosion are distinguished.[ ...]

Geological phenomena such as erosion, formation sedimentary rocks, mountain building and volcanism, can change the physical environment so much that they cause significant shifts in ecosystems.[ ...]

The influence of the geological structure of the territory on the development of erosion is associated with different susceptibility of rocks to erosion and washout, as well as to deflation. Thus, loess and loesslike deposits are easily eroded and contribute to the formation of ravines. Moraine loams are more resistant to washout than mantle loams. Fluvioglacial and ancient alluvial deposits, having good water permeability, are resistant to water erosion, but are easily subject to deflation.[ ...]

Wind erosion can manifest itself to a slight extent with slight air movements. This is the so-called everyday erosion, which is constantly observed in arid regions, but it is not given due importance: dirt roads are dusty, gradually becoming deeper than the general landscape; the fields become dusty when passing any aggregates, and especially trucks when transporting grain, silage, hay and other materials; soil and soil are dusty during the operation of bulldozers and excavators on any construction sites and structures; the soil dusts under the hooves of numerous herds of an ever-increasing number of farm animals. In a word, everyday erosion acts slowly, but with the constancy and inevitability of the geological factor, and an irreconcilable struggle is needed against it.[ ...]

Deforestation contributes to increased soil erosion, shallowing of rivers and lakes. The average rate of deforestation in South-East Asia is 7.1 million ha/year, in the USA - 2.8 million ha/year. So, in the north-east of India, near the spurs of the Himalayas, there is a place called Cherrapunji, where the annual rainfall is up to 9150 mm. Now this "wet kingdom" is threatened by a lack of moisture and even turning it into a desert. The reason is active deforestation, which has been going on for 25 years. As a result of deforestation, bare soil absorbs precipitation poorly, and during the rainy season fertile layer easy to wash out. Limestones, the most common geological rock in Cherrapunji, are exposed and subjected to dissolution by acid rain. As a result, karst sinkholes are formed, actively absorbing water.[ ...]

Soil erosion is distinguished between normal, or geological, and accelerated, or anthropogenic. The first is characteristic of unplowed areas with preserved natural vegetation, where it proceeds more slowly than the formation of the soil profile. The second develops as a result of irrational human activities. In this case, the processes of water and wind erosion are accelerated, ahead of the processes of restoration of the soil profile.[ ...]

With regard to geological phenomena (erosion, sedimentation, mountain building and volcanism), they can also greatly change the biotope, which, in turn, will cause significant shifts in biocenoses. The ongoing development of soils (edaphic factors), which is due to the joint action of climate and living organisms, entails in parallel the development of flora.[ ...]

Under exogenous geological processes is understood the activity of cumulative and single factors (surface and groundwater, gravitational forces, etc.), which lead to a change in the state of the geological environment, resulting in the formation of geological phenomena (erosion, landslides, suffusion, etc.). Geological processes and phenomena are very closely intertwined.[ ...]

The size and rate of erosion depending on the climate and the geological nature of the area, which determine the soil and topographic conditions, and the impact of human economic activity in different occasions will be the most diverse.[ ...]

Undoubtedly, during soil erosion, the degree of their development and the type of profile are also closely related to the rate of the geological process, in this case with denudation.[ ...]

At the stage of engineering and geological surveys, a detailed analysis of the potential threat to the PBU is carried out, created by liquefaction of bottom sediments or loose bottom sediments, subsidence of soil, erosion of sediments caused by waves and currents, objects of artificial origin.[ ...]

As a result of water erosion with surface runoff, a large amount of humus and, consequently, the phosphorus contained in it, is washed off the soil. The soil layer carried away during erosion is 3-5 times richer in organic matter, phosphorus and other biophiles. Currently, about 3-4 million tons of phosphates are washed off the continents and irrevocably buried in the depths of the World Ocean. The movement of phosphorus from the biotic to the geological cycle complicates the phosphorus problem. As a result of phosphorus starvation, the yield of agricultural crops and forage grasses decreases, the quality of feed deteriorates, and the phosphorus nutrition of domestic animals is disturbed.[ ...]

Geomorphological and geological studies confirm the leading role of expanding agriculture in increasing soil erosion and sediment runoff. In the south of Ukraine, in the gullies that do not have a constant flow of water, there are significant sediment deposits accumulated 100-150 years ago, that is, during the agricultural development of the southern steppes. Analysis of sediment cores in the Black Sea showed that the average sedimentation rate in the period 7000-2000 years ago was 90 million tons per year. Then the accumulation rate increased to 250 million tons per year, and it was the highest in the X-XV centuries, when the most active transformation of forests in the Danube basin into agroecosystems took place.[ ...]

EXOGENOUS PROCESSES - geological processes occurring on the surface of the Earth and in the most upper parts the earth's crust (weathering, erosion, glacier activity, etc.). E. p. are mainly due to energy solar radiation, gravity and vital activity of organisms.[ ...]

The zonal geographical conditions of the territory of the Yamburgskoye field determine two groups of factors that have an opposite effect on the dynamics of thermal erosion processes.[ ...]

Anthropogenic impact on the processes of soil erosion in terms of scale and consequences is comparable to the geological one, especially in areas of intensive human management and a low level of anti-erosion measures. The forms of this influence, as follows from the following, are diverse.[ ...]

The development of the geotechnosphere activates traditional geological processes: the ancient mountainous folded area seems to be re-living the stage of seismic, hydrothermal and even magmatic activity (technogenic earthquakes, pyrite and coal fires, a sharp increase in erosion, an increase in ion flow). In general, modern technogenesis, which includes industrialization and urbanization, in terms of the totality of phenomena (technogenic seismicity, an increase in suspended and ionic runoff, “hydrothermal” and “magmatic” activity) is similar to the tectonic-magmatic activation of the Ural mountain-fold belt.[ .. .]

Deflation of soils is their destruction with the help of wind. There is geological erosion or decoupage, when the destruction of soils is compensated by soil-forming processes, which preserves the character of the developed surface. Allocate anthropogenic erosion and deflation - the accelerated destruction of soils and rocks with the help of water in connection with economic activity.[ ...]

At the same time, as in the case of pollution processes, the technogenic impact on the geological environment (GS) is not the same at different stages of the development of hydrocarbon deposits. At the stage of prospecting, it is minimal and has a short-term, mainly exogenous character, mainly it is a disturbance of soils associated with their mechanical compaction and erosion. However, these processes can give impetus to the degradation of permafrost soils with the formation of thermokarst, thermoerosive and other forms of surface disturbance, the development of eolian processes, gully formation, planar washout, etc. In this case, soils change as substrates for soil formation and a violation of the natural thermal and hydrological balances on road sections, field bases and geophysical profiles.[ ...]

Eutrophication is a term for the "aging" of a lake. It contains a little nutrients, and its biomass load is low. Natural processes such as wind erosion and leaching by rainwater cause additional nutrients to enter the lake, which stimulates plant and animal life in it. The lake begins to silt up at a rate that can be determined from Gill's empirical model. The latter applies to reservoirs as well. The Old Lake is eutrophic: the water quality is low, the biomass load is high and the moment when it should disappear is not far (in geological time scales).[ ...]

Purposeful studies of thermal erosion began to be carried out at Moscow State University in the problematic laboratory of soil erosion and channel processes since 1969, somewhat later - at the Department of Permafrost Science of the Faculty of Geology. So, in 1970 - 1977. employees of the department were engaged in the study of tormo-erosion in the lower reaches of the Yenisei. Under the leadership of E.D. Ershov, a large amount of laboratory research was carried out to study the mechanism and patterns of erosion of frozen rocks.[ ...]

Changes in the geographical envelope also occur as a result of the movement of the continents, the advance and retreat of the seas, in the course of geological processes: during erosion and accumulation, the work of the sea, volcanism. In general, the geographical shell is developing progressively, from simple to complex, from lower to higher.[ ...]

The types of some reservoirs are shown in Fig. 140-142. There are no sharp boundaries between these groups, as well as within each of them. In general, lakes are filled with solid material, and river valleys cut deeper and deeper into the earth's surface. All these changes occur as a result of the action of water. When the river valley reaches its erosion base, the current slows down, sedimentation occurs and a flat meandering river is formed. However, under appropriate conditions, uplifts can form in any part of the valley, even if silt deposits have already built the river delta. Then the general erosion cycle begins again. The complex interaction of autogenous (internal, successional) and allogeneic (external) processes in freshwater reservoirs was discussed in sufficient detail in Chap. 9.[ ...]

A feature of post-war research is an attempt to differentiate anti-erosion measures depending on climatic, soil, geological, hydrological and geomorphological conditions and to create regional systems of anti-erosion measures as an integral part of regional economic management systems. at the Soil Institute. V.V. Dokuchaev continued to work vigorously the department of soil erosion, headed for 30 years by S.S. Sobolev. On his initiative, the institute organized all-Union and regional conferences and meetings on the protection of soils from erosion. Their results were published in the collections Soil Erosion and its Control (1957), Soil Protection from Erosion (1964) and others. S.S. Sobolev owns numerous publications on topical issues soil protection. Of particular importance is his two-volume monograph "The Development of Erosion Processes on the Territory of the European Part of the USSR" (1948, 1960). The work of the staff of the department during this period made a great contribution to the development of the problem of classification and mapping of eroded soils, the effectiveness of erosion control measures in various natural conditions.[ ...]

Agricultural production in most of the territory of Russia is carried out in relatively unfavorable climatic and soil-hydrological conditions. And the main troubles are soil erosion and drought. Erosion is a natural geological process, which is often exacerbated by imprudent economic activities. More than 54% of agricultural land and 68% of arable land is currently eroded or dangerous for erosion. On such lands, productivity is reduced by 10-30%, and sometimes by 90%.[ ...]

The fourth stage of development of ravines (the stage of attenuation) occurs when the longitudinal profile of the ravine reaches parameters close to the value of the limiting “equilibrium” profile; at this time, bottom erosion stops, further development of the slopes takes place, aimed at reducing the angles of inclination and flattening the edges. The removal of loose rocks decreases with an increase in the area of ​​sodding of slopes and bottoms of ravines. With complete sodding, the growth of ravines changes quantitatively and qualitatively. The quantitative one consists in a sharp reduction in the removal of fine earth, and the qualitative one in the transition of the processes of linear and planar erosion (accelerated) into slow processes of geological denudation. Further changes in all parameters of sod ravines will occur over centuries and even millennia.[ ...]

The soil-vegetation layer itself is a stabilizing factor, it “armours” the surface to a certain extent, but, being a rather fragile natural object, it is easily destroyed under the conditions of an uncharacteristic geological regime. Its restoration is possible only upon termination of the most active destructive processes, primarily erosion and permafrost phenomena.[ ...]

The term "corrosion" currently characterizes the processes of natural destruction under the influence of the environment of metals, alloys and non-metallic materials, products from them, i.e. products of anthropogenic origin. Erosion refers to the processes of destruction under the influence of the environment of material objects of natural origin (rocks and soils). However, until now, the concept of "corrosion" in some cases is used to refer to geological processes of destruction, for example, the dissolution of rocks as a result of exposure to water with the formation of karst (hollow) landforms. The process of erosion sometimes refers to the gradual destruction of the surface of material objects created by man, for example metal products, in gas or liquid flows, under the influence of electrical discharges, etc. In this paper, both concepts are used in their basic meanings in modern Russian.[ ...]

The main core of the Nevadian-type margins are complexes of powerful accretionary uplift, which form not only the borderland - the underwater part of the continent, but also vast land areas. Sedimentation processes in the geological epochs closest to us took place here in medium-sized but deep basins confined to subsided blocks in the topography of the accretionary structure. Analysis of the formational composition of sediments on the Nevadian margins is hampered by the poor preservation of sedimentary formations due to repeated tectonic deformations, erosion and metamorphism, mainly high-pressure metamorphism.[ ...]

Less than a century after the emergence of the new situation, the impact of the human race on the environment has increased so much that its result has become different in its essence. For example, at the beginning of the 14th century, the first cannons were fired, and this had environmental consequences - deforestation and erosion, because workers were sent to the mountains and forests to extract large quantities of potash, sulfur, iron ore and charcoal. Today's hydrogen bombs are already very different: if they are used in war, the genetic basis of all life on Earth will most likely change. In 1285 London had its first smog problems from burning bituminous coals, but they are nothing compared to the fact that the current burning of fuel threatens to change the chemical basis of the global atmosphere as a whole, and we have only begun to understand something, what could be the consequences. The population explosion and the cancer of unplanned urbanization have created garbage dumps and sewage volumes of truly geological proportions, and, of course, no other living creature on Earth, except man, could desecrate his nest so quickly.[ ...]

The geodynamic ecological function of the lithosphere is a function that reflects the properties of the lithosphere to influence the state of the biota, the safety and comfort of human life through natural and man-made processes and phenomena. Urbanization leads to disruption of spatio-temporal and intensity inhomogeneities in the manifestation of geological processes, both natural (landslides, karst, subsidence of loess, ravine erosion and earthquakes) and new man-made (flooding, subsidence of the surface and thermal subsidence). These changes lead, as a rule, to negative environmental consequences, and sometimes to positive ones associated with the stabilization of geological processes.[ ...]

Significant damage natural environment inflict quarries for the extraction of mineral raw materials and waste from their processing. The total area of ​​quarries and dumped rocks, enrichment waste from mining and processing plants is over 180 thousand hectares. As a result of the extraction of mineral raw materials, hundreds of millions of tons of rocks of various geological ages have been brought to the surface. In addition, hundreds of millions of tons of wastes from the enrichment of mineral ores, the coal industry, which are mainly represented by “dead” substrate, easily spread hundreds of kilometers from storage sites, were dumped. At Mikhailovsky GOK alone, more than 1 billion tons of rocks and enrichment wastes were brought to the surface. In place of natural, stable biogeocenoses and agrolandscapes, new technogenic landscapes have formed, which are sources of industrial erosion, since their surface is very unstable due to the long absence of green plants on their surface.[ ...]

In many cases, water is a key factor in major global environmental problems. The exceptional role of water as an agent carrying dissolved, entrained and suspended substances has already been noted above. Therefore, it is the most important factor in the global biogeo about the chemical cycles of carbon, nitrogen, sulfur, phosphorus, etc., and in the exogenous part of a large geological cycle (or erosion-sedimentation cycle). The global hydrological cycle is one of the main life-supporting mechanisms of the ecosphere, which at the same time depends on changes in its state.[ ...]

Environmental problems associated with the violation of individual components of the landscape or their complex can be divided into six groups: 1) atmospheric (atmospheric pollution: radiological, chemical, mechanical, thermal); 2) water (depletion and pollution of surface and ground waters, pollution of seas and oceans); 3) geological and geomorphological (intensification of unfavorable geological and geomorphological processes, disturbance of the relief and geological structure); 4) soil (pollution, erosion, deflation, secondary salinization, waterlogging, etc.); 5) biotic (reduction of vegetation, degradation of forests, pasture digression, reduction of species diversity, etc.); 6) complex, or landscape (desertification, biodiversity decline, violation of the regime of protected areas, etc.).[ ...]

In the loess-soil layer of Eastern Europe several buried soils are also identified (Velichko, 1997). The soil cover of the last interglacial, which was formed about 100 thousand years ago, is most clearly expressed. According to the set of soil types and their geography (zonality, provinciality and other patterns of structure soil cover) it is in many respects similar to the modern one (Morozova, 1981). Zoning is also characteristic of older interglacial soil covers. During long periods glacial cooling was dominated by geological processes, erosion and sedimentation, but soil formation did not completely stop. Loesses contain traces of synlithogenic (syngenetic) arid pedogenesis and, to some extent, are soils (according to O.P. Dobrodeev, special soils without a profile).[ ...]

Reducing the filtration of melt and rain water by arable land led to a decrease in the level and drainage of the upper aquifers, the drying up of springs, a reduction in the low flow of small rivers up to a complete cessation. Close spatial and temporal dependence of low-water runoff and level modules ground water from forest cover indicates that a decrease in filtration and underground feeding of rivers is main reason their degradation. Rivers dry up even where the flow of basin erosion products into their channels does not occur or is very limited. Under different geological and hydrogeological conditions, this degradation proceeds differently. It is more distinct in river basins composed of well-permeable rocks (for example, the Upper Cretaceous and Paleogene of the Volga Upland).[ ...]

LITORAL (L.) - in the sea, a zone covered with water at high tide and drained at low tide; in the lakes of L. they call the coastal shallow part, often overgrown with various aquatic plants- hydrophytes. See also Marine ecosystems, Freshwater ecosystems. LITHOSPHERE (L.) - upper hard shell Earth, the thickness of which is 50-200 km. Upper layer L. is called the earth's crust. At present, humans are exerting the strongest technogenic influence on L., which has become one of the factors in the destruction of the biosphere. The scale of technogenic influence (especially due to the development of erosion processes, increased solid runoff, burning of fossil fuels and the creation of engineering structures) has reached colossal values ​​that exceed the intensity of natural flows of matter. Man has become the main geological force of the planet.[ ...]

According to the expedition of the International Independent Environmental and Political University (1966), in the Eastern Khibiny, as a result of processes in the formed undermined territory, deep subsidences arose over underground mine workings. As a result, the formation of a technogenic mudflow center began. Initially, the bedrock exposed after subsidence underwent active weathering and created “reserves” a large number fine-grained material in the upper parts of the slopes. These weathering products and the actual faded rocks "arrived" at the disposal of such geological processes as suffusion and erosion, which gradually flatten the slopes. As a result of the combined action of these two factors, conditions are formed for the accumulation of detrital material and the formation of a "route" for its movement down the slope. A prerequisite is created for snow-stone mudflows - the rapid movement down the slope of a large mass of waterlogged fine-grained material mixed with snow. The manifestation of emergence in the development of the landscape leads here to a change in the nature of its development from relatively calm to stormy, associated with catastrophic processes leading to much faster destruction of the slope.[ ...]

V last years Numerous experiments have been carried out to study other ways to eliminate waste from intensive animal husbandry. One of the simplest methods in the order of experience was used in the USA. It consists in plowing waste. This method differs from the elimination of waste by applying as a fertilizer only technologically. Here in the foreground is the disposal of waste, and not the fertilization of the fields, corresponding to the needs of plants in nutrients. At the place of incorporation of waste, as a rule, it is impossible to further grow crops for a long time. Waste disposal is possible only where, from a geological point of view1, garbage dumps do not pose a danger from the point of view of environmental pollution and erosion does not occur. This extensive ER method is hardly suitable for conditions in Central Europe, where agricultural land is becoming more and more expensive.

The impact of the flow on the channel is manifested in the formation of meanders, leading to the expansion of the river valley, and in the deepening of the channel to the level of the limiting equilibrium profile corresponding to the position of the erosion basis. Thus, two directions are distinguished in the eroding work of the river: lateral erosion, leading to the expansion of the valley, and deep (bottom) erosion, expressed in the incision of the channel. You can always find signs of both types of erosion, however, in different parts of the river and in different periods of the formation of its valley, either deep or lateral erosion prevails.

Lateral erosion. Rivers are not straight and always form bends, or meanders (the name comes from the meandering river Meander in Asia Minor). Experiments in straightening the riverbed, carried out in Europe, showed that rivers artificially introduced into straight banks soon began to erode them and again became winding. This happens because even with a rectilinear channel, the distribution of flow velocities in the stream has a helical character, due to which the right and left banks are alternately washed out. On curved stretches, this process is sharply enhanced. The jets running onto the concave shore go down and create a near-bottom current directed towards the opposite shore. The transverse circulation is superimposed on the general translational movement of the water and creates a helical movement clockwise when the channel bends to the left (when viewed downstream) and counterclockwise when the channel bends to the right.

The flow of rivers on bends usually presses against the concave bank and it is intensively washed away, and a spit is washed along the convex bank. Therefore, the convex banks near the rivers are gentle, and the concave ones are steep, with maximum depths located near them. Erosion of concave banks leads to the growth of meanders, to a change in their shape and, ultimately, to the expansion of valleys (Fig. 42). During floods, rivers often make bends for themselves, eventually becoming the main channel, and the bends turn into backwaters and old rivers (oxbow lakes, lakes), or even fill with sediment. Lateral erosion shifts to another area, gradually deforms it and expands it.

The expansion of the valley cannot, however, continue indefinitely: with the formation of bends, the length of the channel increases, and its slope and flow velocity decrease accordingly. The kinetic energy of the flow is sharply reduced, and although lateral erosion does not stop and the river continues to wash its deposits and move the channel from side to side, the expansion of the valley no longer occurs. At this time, the impact of the flow on the channel leads to the reverse effect of the channel on the flow. At each moment, the velocity field of the flow is determined by the shape of the channel, but under conditions of a moving channel, this velocity field cannot be stable. In sections of the river with eroding current velocities, the channel is deformed, and where the velocities are low, partial sedimentation occurs. The flow deforms the channel, and the changed channel, in turn, rebuilds the velocity field of the flow. The flow affects the channel most intensively during floods and high floods, when not only the water discharge, but also the speed of the flow changes more or less sharply. Valleys experiencing lateral erosion usually have an uneven width: in areas of outcrop of strong rocks, they are much narrower than in areas composed of easily eroded rocks.

Weak soils called soils that cannot take the load, for the stability of the buildings and structures being built, their strengthening is required. The following methods are used to strengthen soils: replacing weak soils with more reliable ones, their surface and deep compaction, cementation, chemical, thermal, synthetic resin fixing of soils, etc.

The replacement of weak soils comes down to the fact that instead of them, for example, peat bogs or silty soils, sand is laid with tamping. This method is called the sand cushion device. However, such a replacement is possible only to a depth. Compaction of weak soils can be superficial to a depth of 2-2.5 m and deep to a slightly greater depth. For surface compaction, heavy rammers are used, as well as vibrators, and thus, violating the natural structure of the soil, it is compacted. In deep compaction, special pipes with cores are used to compact the soil around each pipe, and the resulting cavities are filled with sand or lean concrete. The wells are arranged in a checkerboard pattern at a distance of 0.9-1.5 m from one another, according to the calculation.

11 . Cryogenic soil structural bonds- crystallization bonds that occur in wet dispersed and fractured rocky soils at negative temperatures as a result of ice cementing.

12 . GENERAL CLASSIFICATION OF GEOLOGICAL AND ENGINEERING GEOLOGICAL PROCESSES AND PHENOMENA. INDICATORS OF THEIR DEVELOPMENT INTENSITY

13 . Geomorphology(from other Greek γῆ - Land + μορφή - form + λόγος - doctrine) - the science of relief, its appearance, origin, history of development, modern dynamics and patterns of geographical distribution. The fundamental question: "What does the process that forms the terrain look like?" Geomorphologists attempt to understand the history and dynamics of landform change, and predict future changes through field measurements, physical experiments, and mathematical modeling. In practice, the discipline is directly related to geography, geology, geodesy, archeology, soil science, planetology, and construction. The author of the term geomorphology can be considered the famous American geologist and geomorphologist John William McGee.

Landforms are distinguished according to their genesis and size. The relief is formed under the influence of endogenous (tectonic movements, volcanism and crystallochemical deconsolidation of the subsoil matter), exogenous (denudation) and cosmogenic processes.

The practical application of geomorphology is in the engineering assessment of the relief during construction, measuring the impact of climate change, forecasting and mitigating the consequences of catastrophic events (landslides, landslides, etc.), monitoring the water supply of territories, and coastal protection.

Landforms By origin:

tectonic - arise as a result of the movement of the earth's crust;

erosional - associated with the destructive work of flowing waters;

accumulative - a consequence of the accumulation of products of destruction of rocks by water and wind.

Terrain types

Type of relief (this is a certain combination of landforms, regularly repeating over vast expanses of the earth's surface). There are three types of terrain: flat, mountainous and hilly.

Relief age. An important task of geomorphology, along with the study of morphography, morphometry and genesis, is to clarify relief age. As is known, in geology, the age of rocks is one of the most important geological characteristics, and it, in essence, constitutes the main content of general geological maps.

The geological age of rocks is determined using well-developed stratigraphic, paleontological and petrographic methods, which have recently been increasingly supported by methods of absolute geochronology. In geomorphology, age determination is a more complex task, since geological methods are applicable only to accumulative landforms and cannot be used directly to determine the age of a worked out (denudation) relief. In geomorphology, as in geology, one usually uses concepts of "relative" and "absolute" age of the relief.

Relative age of the relief. The concept of "relative age of relief" in geomorphology has several aspects.

1. The development of the relief of any territory or any particular form, as shown by V. Davis, is a stage-by-stage process. Therefore, the relative age of the relief can be understood as the determination of the stage of its development. As an example, we can trace the development of river valleys . Therefore, one aspect of determining the relative age of a relief is determination of the stage of its development by a complex of characteristic morphological and dynamic features.

2. The concept of "relative age of the relief" is also used in the study of the relationship of some forms with others. In general, any form is older than those that complicate its surface and were formed at a later time.

3. Determining the relative geological age of a relief means establishing the period of time when the relief acquired features that are basically similar to its modern appearance. If we are talking about accumulative landforms, then the question is reduced to determining the age of the deposits composing this form by conventional geological methods. Thus, river terraces composed of Middle Quaternary deposits are of Middle Quaternary age; ancient dunes, composed of eolian Pliocene deposits, are of Pliocene age, etc.

The absolute age of the relief. In recent decades, due to the development of radioisotope research methods, the determination of the age of deposits and landforms in absolute units, in years, has been widely used. To do this, it is necessary to know the half-life of a particular radioisotope; then determine the ratio of its amount in the deposits with the derivative.

relief genesis. The main starting point of modern geomorphology is the idea that relief is formed as a result of the interaction of endogenous and exogenous processes. However, this thesis should be detailed when considering specific forms or complexes of relief forms.

As mentioned earlier, the largest landforms are of endogenous origin, while the smaller ones are exogenous. Exogenous processes in the course of their activity, they either complicate or simplify the relief of endogenous origin. In some cases, exogenous agents produce smaller meso- and microforms, in others they cut off irregularities created by endogenous processes, in others, the endogenous relief is buried or complicated due to the formation of various accumulative forms. The nature of the impact of exogenous agents on the relief of endogenous origin is largely determined by the trend in the development of the relief, i.e., by whether ascending (positive) movements of the earth's crust or descending (negative) movements are dominant.

According to existing ideas, the main source of energy for endogenous relief-forming processes is thermal energy, produced mainly by gravitational differentiation and radioactive decay matter in the interior of the earth. Gravity and radioactivity, heating and subsequent cooling of the Earth's interior inevitably lead to changes in the volume of masses of the substance that makes up the mantle and the earth's crust. The expansion of the earth's matter during heating leads to the emergence of upward vertical movements both in the mantle and in the earth's crust. The earth's crust reacts to them either by deformations without rupture of layers (the formation of plicative dislocations), or by ruptures and displacement of crustal blocks limited by ruptures (disjunctive dislocations).

14. EROSION PROCESSES- a complex of processes of erosion of soils, soils, banks and riverbeds carried out by water flows, one of the factors in the formation of relief and sediment runoff (see). Distinguish between soil erosion (see) (flat washout), produced on the slopes by temporary non-conditional flows of melt and rainwater, ravine erosion (see), associated with the activity of temporary flows, concentrating in furrows and other linearly elongated depressions on slopes, in beams, and river erosion. Normal soil erosion corresponds to conditions under which the washout of the surface layer does not exceed the accumulation of humus in the soil during soil formation. Accelerated soil erosion is accompanied by a loss of humus, which is not compensated by the soil-forming process, resulting in a decrease in the natural fertility of soils; usually identified with anthropogenic soil erosion, as it is associated with the plowing of land and the replacement of natural vegetation with artificial crops. Soil erosion is carried out by formation flows covering the surface of the slope with a continuous film, or by streams that occur when water enters the uneven microrelief of the slopes and into the newly formed primary erosion furrows, which are not constant in time due to the continuous change in their position. Ravine erosion develops if such an amount of flowing water is concentrated in the primary erosion gully (furrow), the flow (see) of which can remove the flow solid material from the above site, as well as when the flow cuts and the sides of the gully collapse. This condition depends on the size of the catchment area of ​​the ravine, the slope of the slope, the mechanical composition of the soil, and other factors. Often under E.p. imply soil erosion and ravine erosion. River erosion is subdivided into lateral erosion - erosion of the banks of rivers, leading to a shift in their channels and expansion of valleys, and deep erosion (see), accompanied by erosion of the river bottom and deepening of river valleys. The geomorphological effect of deep erosion of rivers affects the geological time scale. Lateral erosion is associated with the stability of river channels and, depending on the erosion of the rocks that make up the banks, it can take on catastrophic proportions (deigish on the Amu Darya causes the banks to retreat hundreds of meters in a few days) or it affects only for millennia; Usually coastal erosion (lateral erosion) occurs at a rate of 2-10 m/year. E.p. lead to soil erosion, decrease in their fertility, dismemberment of lands by ravines, destruction of agricultural land, engineering facilities and communications, which necessitates their forecasting and development of measures to prevent or protect.

Erosion(from lat. erosio- erosion) - the destruction of rocks and soils by surface water flows and wind, including the separation and removal of fragments of material and is accompanied by their deposition.

soil erosion- destruction and demolition of the upper most fertile soil horizons.

Often, especially in foreign literature, erosion is understood as any destructive activity of geological forces, such as sea surf, glaciers, gravity; in this case, erosion is synonymous with denudation. However, there are also special terms for them: abrasion ( wave erosion), exaration ( glacial erosion), gravitational processes, solifluction, etc. The same term (deflation) is used in parallel with the concept wind erosion, but the latter is much more common.

According to the rate of development, erosion is divided into normal and accelerated. Normal occurs always in the presence of any pronounced runoff, proceeds more slowly than soil formation and does not lead to a noticeable change in the level and shape of the earth's surface. Accelerated is faster than soil formation, leads to soil degradation and is accompanied by a noticeable change in relief.

For reasons allocated natural and anthropogenic erosion. It should be noted that anthropogenic erosion is not always accelerated, and vice versa.

wind erosion

This is the destructive action of the wind: waving sands, forests, plowed soils; occurrence of dust storms; grinding of rocks, stones, buildings and mechanisms with solid particles carried by the force of the wind. Wind erosion is divided into two types:

Casual

dust storms

The beginning of a dust storm is associated with certain wind speeds, however, due to the fact that flying particles cause a chain reaction of detachment of new particles, it ends at speeds much lower.

The strongest storms took place in the USA in the 1930s (“Dusty Bowl”) and in the USSR in the 1960s, after the development of virgin lands. Most often, dust storms are associated with irrational human economic activity, namely, the massive plowing of land without carrying out soil protection measures.

There are also specific deflationary landforms, the so-called " blowing basins": negative forms, elongated in the direction of the prevailing winds.

water erosion drip erosion

Destruction of the soil by impacts of raindrops. Structural elements (lumps) of the soil are destroyed under the action of the kinetic energy of raindrops and are scattered to the sides. On slopes, downward movement occurs over a greater distance. Falling, soil particles fall on a film of water, which contributes to their further movement. This type of water erosion is of particular importance in the humid tropics and subtropics.

Planar erosion Planar (surface) erosion is understood as a uniform washout of material from slopes, leading to their flattening. With some degree of abstraction, they imagine that this process is carried out by a continuous moving layer of water, but in reality it is produced by a network of small temporary water flows.

Surface erosion leads to the formation of eroded and reclaimed soils, and in more large scale- deluvial deposits.

Linear erosion Unlike surface erosion, linear erosion occurs on small areas surface and leads to the dissection of the earth's surface and the formation of various erosional forms (gullies, ravines, gullies, valleys). This also includes river erosion produced by constant flows of water.

The eroded material is deposited usually in the form of alluvial fans and forms proluvial deposits.

Types of linear erosion

Deep(bottom) - destruction of the bottom of the watercourse. Bottom erosion is directed from the mouth upstream and occurs before the bottom reaches the level of the erosion basis.

Lateral- destruction of the coast.

In each permanent and temporary watercourse (river, ravine), both forms of erosion can always be found, but at the first stages of development, the deep one prevails, and in the subsequent stages, the lateral one.

Mechanism of water erosion

Chemical exposure surface water, which include the waters of rivers, is minimal. The main cause of erosion is the mechanical impact on the rocks of water and the debris carried by it, previously destroyed rocks. In the presence of debris in the water, erosion increases sharply. The greater the flow velocity, the larger the debris is transferred, and the more intense the erosion processes.

To assess the resistance of soil or soil to the action of a water flow, you can critical speeds:

Non-smearing speed - the maximum flow rate at which there is no separation and movement of particles.

Scouring speed - the minimum flow rate at which the incessant detachment of particles begins. (Mirtskhulava T. E. Erosion of channels and a technique for assessing their stability. - M .: Izd-vo, Kolos, 1967.)

For soils and polydisperse soils, the concept of non-erosion velocity has no physical meaning, since even under the most low speeds the removal of the most small particles. With a turbulent flow, particles detachment occurs at maximum pulsation velocities, therefore, an increase in the amplitude of flow velocity fluctuations causes a decrease in critical velocities for a given soil.

spreading erosion

Erosion processes are widespread on Earth everywhere. wind erosion prevails in arid climate conditions, water erosion- in a humid climate.

EROSION BASIS- the surface at the level at which the water flow (river, stream) loses its living power and below which it cannot deepen its bed. Distinguish B. e. general and local. For B. e. the general, or main, is conditionally accepted as the level of the World Ocean, although in fact all rivers flowing into the seas and oceans deepen their channels below sea level, being overdeepened at the mouths. This is explained by the fact that the rivers at the mouth still have a large supply of energy and continue to erode their channel until the dynamics of the river fades and is replaced by the dynamics of the wave process and the dominance of tidal currents. The distance of river erosion on the seabed depends on the water content of the river, the speed of its flow, the flow regime and the depth of the coastal part. Local B. e. are located at any height and can be either permanent” (ocean level, drainless reservoir, for example: the Caspian and Aral Seas, etc.), or temporary. Any point of the riverbed, including the mouths of tributaries, and especially waterfalls and porgia are local B. e., continuously changing, but determining erosion in the higher located area.

16 . Alluvium(lat. Alluvio- sediment, alluvium) - non-cemented deposits of permanent water flows (rivers, streams), consisting of fragments of varying degrees of rolling and sizes (boulder, pebbles, gravel, sand, loam, clay). The granulometric and mineral composition and structural and textural features of alluvium depend on the hydrodynamic regime of the river, the nature of the rocks that are washed in, the relief and the catchment area. River deltas are composed entirely of alluvial sediments and are alluvial fans. The presence of alluvial deposits in the section is a sign of the continental tectonic regime of the territory.

The study and classification of alluvial deposits were carried out by such well-known researchers of Quaternary geology as E. V. Shantser, V. T. Frolov, Yu. In general, continental alluvial deposits are classified by genesis (mountain and lowland rivers), facies (channel, floodplain and oxbow), formation phases, forms of alluvial bodies, etc. It should be noted that the classification of alluvium by formation phases was developed back in In the Soviet Union, the so-called "school of Soviet geology", and the classification of alluvial deposits according to morphological forms was developed and widely used by geologists in Western Europe and the USA, in particular, H. Reading.

Wind erosion (deflation)

It is divided into two types:

• Casual
• dust storms

The beginning of a dust storm is associated with certain wind speeds, however, due to the fact that flying particles cause a chain reaction of detachment of new particles, it ends at speeds much lower.

The strongest storms took place in USA v 1930s years ( dusty cauldron) and in the USSR v 1960s after development of virgin lands and are associated with irrational human economic activity: massive plowing of land without carrying out soil protection measures.

There are also specific deflationary forms of relief - blowout basins - negative forms, elongated in the direction of the prevailing winds.

water erosion

surface erosion

Under the surface erosion understand the uniform washout of material from the slopes, leading to their flattening. With some degree of abstraction, they imagine that this process is carried out by a continuous moving layer of water, but in reality it is produced by a network of small temporary water flows.

Surface erosion leads to the formation of washed-out and reclaimed soils, and on a larger scale - deluvial deposits.

Linear erosion

Unlike surface erosion, linear erosion occurs in small areas of the surface and leads to the dismemberment of the earth's surface and the formation of various erosion forms (gully, ravines, beams, valleys). This also includes river erosion produced by constant flows of water.

Washed-off material is usually deposited in the form of alluvial cones and forms proluvial deposits.

Types of linear erosion

• Deep(bottom) - destruction of the bottom channels watercourse. Bottom erosion is directed from mouth upstream and occurs until the bottom reaches the level erosion basis.
• Lateral- destruction of the coast.

In each permanent and temporary watercourse ( river , ravine) it is always possible to detect both forms of erosion, but at the first stages of development, the deep one prevails, and in the subsequent stages, the lateral one.

Mechanism of water erosion

The chemical impact of surface waters, which include river waters, is minimal. The main cause of erosion is the mechanical impact on rocks water and the debris carried by it, previously destroyed rocks. In the presence of debris in the water, erosion increases sharply. The greater the flow velocity, the larger the debris is transferred, and the more intense the erosion processes.