The main types of landforms of the Earth: fluvial, karst, glacial, aeolian, coastal. Karst and aeolian processes are Aeolian processes accompanied by

, archaeology, soil science, planetology, as well as construction.

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

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

Paleogeomorphology- a branch of geomorphology that studies the appearance of the Earth's surface during certain periods of history.

Story [ | ]

The founder of geomorphology was the Chinese scientist and statesman Shen Kuo (1031-1095), who observed the shells of marine animals located in the geological layer of a mountain located hundreds of miles from the Pacific Ocean. Noticing a layer of shells of bivalve mollusks moving horizontally along the cross section of the cliff, he suggested that this cliff was previously a sea coast, which over the centuries has shifted hundreds of kilometers. He concluded that the shape of the earth had changed and formed due to soil erosion and sediment deposition by observing the erosion of mountains near Wenzhou. In addition, he put forward the theory of gradual climate change over the centuries, since ancient bamboo remains were found in the dry northern climate zone Yangzhou, now Shaanxi Province. However, the pioneering works of Shen Kuo did not influence the development of geomorphology as a scientific discipline in other countries, since nothing was known about these views of the Chinese scientist until the 20th century.

The founder of modern geomorphology in the TSB is the German geologist Ferdinand von Richthofen. Based on the materials of his own long-term expeditionary research, he “collected enormous material that allowed him to establish a deep internal connection between the geological structure and the relief, climate, vegetation, wildlife and human economic activity.”

Richthofen defined geography as the science of the components of the earth's surface in their interaction, which made it possible to look at the development of relief as a dynamic system that changes in time and space.

Richthofen first proposed a classification of geographical sciences, dividing them into physical geography, biogeography and anthropogeography. As part of physical geography, he identified a new scientific discipline, which he defined as geomorphology*

In 1886, Richthofen proposed a classification of landforms based on its genesis, which predetermined the future work of William Maurice Davies and Walter Penck.

The geomorphological model proposed by William Maurice Davies, between 1884 and 1899, was called geographical cycle or erosion cycle. This cycle was tied to the principle of actualism, which was formulated by James Hutton. Regarding depressions, this cycle relied on the sequence with which rivers can carve deeper and deeper depressions, but then bank erosion eventually levels the area again, now lowering it. The cycle may begin to lift the territory again. This model is now considered with significant simplifications for more convenient use in practice.

Age of the ocean floor. Red color is the youngest

Processes [ | ]

Modern geomorphology focuses on quantitative analysis interrelated processes such as the role of solar energy, the rate of the water cycle, and the rate of plate movement to calculate the age and expected future of individual landforms. The use of precision computing technology makes it possible to directly observe processes such as erosion, whereas previously it was possible to rely on assumptions and conjectures. Computer modeling is also very valuable for testing a specific model of an area with properties that are similar to the real area.

The relief is formed as a result of the interaction of endogenous and exogenous processes.

Endogenous processes[ | ]

Tectonic movements[ | ]

Tectonic (vertical and horizontal) movements create the largest forms of relief (megarelief). For example, large flat areas and mountainous countries.

Magmatism [ | ]

If rivers flow across a plain, they usually increase in size, joining with other rivers. A network of rivers thus forms a river system, often the rivers are dendritic (branching), but they can take on other forms that depend on the specific surface and geological structure.

Glacial geomorphology[ | ]

Glaciers are an important force transforming the relief. The gradual downward movement of ice causes corrosion of the underlying rocks. Corrasia produces a fine coating called ice powder. The rock debris transported within the ice sheet and at its base is called a basal moraine.

Aeolian processes[ | ]

Got their name from greek god winds of Aeolus. These are the processes of relief formation under the influence of wind. Accumulative forms (for example, dunes) and denudation forms (for example, blowing ditches along roads in the desert) are formed. The main active factor is wind-sand flow (particles are captured from the surface at wind speeds above 4 m/s).

Coastal processes[ | ]

This is the formation of relief in the coastal zone of seas, lakes, etc. Accumulative and denudation forms are formed. An example of accumulative ones is beaches, and denudative ones are cliffs.

Biogenic processes[ | ]

This is the formation of relief under the influence of living organisms. Examples: paths in forests, sparks, termite mounds, dams, in tropical seas - coral reefs (fringing, barrier and atolls).

Anthropogenic processes[ | ]

Changes in relief by humans. This process is observed during open-pit mining of mineral resources in quarries, road and hydraulic engineering construction, exploitation of cities and industrial centers, agricultural work.

Cosmogenic processes[ | ]

They are characteristic of the Earth group planets, but are not the main factors of relief formation. An example of a landform: an impact crater (the first to be classified as such)

Exogenous processes - occur on the surface of the earth under the influence of the radiant energy of the sun and are transformed into the energy of movement of water, lithosphere substances, these include the activity of rivers, lakes, wind, glaciers, seas, etc.

These processes of change proceed in the overwhelming majority 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

Fluvial- a set of geomorphological flows carried out by permanent and temporary water flows. In Geological work of water: Destruction of hydraulic reservoirs, Movement of products of washout and erosion, deposition of transported products (accumulation)

Water erosion is the process of washing away rocks and soils, tearing off and carrying away particles.

Flat washout (horizontal erosion) - the removal of soil particles by rain and melt water along a relatively flat slope. Diluvium - well-sorted weathering products redeposited by the atmosphere. precipitation along the slopes of the watershed. (Meaning: flattening the slope from weathering products)

Deep erosion - flat erosion occurs only on smooth slopes, if there are irregularities - the streams move in the direction of the slope and erode the surface in depth, forming water-erosive FR (Erosion furrow - the original form of temporary watercourses, is small in size; ravines - an open negative form with steep slopes , deepened to 50m, length 3-5km, width up to 150-300m

The basis of erosion is the horizon surface. From which erosion began and below which destruction cannot occur

Gullies (coastal, bottom, inclined). The growth of ravines depends on climate, topography, human activity, etc.

Landslides and mud flows - processes occur on large slopes and are most pronounced in the mountains; usually there is no water in them

Glacial– ice activity, image of glaciers. (mountain and cover or continental glaciers). When a glacier moves (movement speed up to tens of M per day, depends on the slope): destruction of rocks, transportation of material, accumulation of material

Exaration – glacial gouging, exogenous. The process of destruction of glacial GPs.

Exaration F:

Plowing basins - image. With the pressure of glaciers and the plowing out of uneven bases of depressions. Lamb foreheads. In the mountains there are pits (cruciform shapes on mountain slopes), troughs, cirques (depressions in the rocks where pits merge).

In the zone of glacier accumulation the image is: hills of the main moraine, druslins, moraine ridges.

Fluvioglacial– when glaciers melt, the image of water flows. (Shapes: Eskers - narrow, long, straight or winding ridges parallel to the movement of the glacier, similar to railway embankments (length - 10 km, width - 150 m, height - 100 m). Kama - hills, 30 m high or more, composed of layered fluvioglacial deposits cm (round, cone-shaped)). Outwash fields are gentle, flat, large-radius glacial flow cones; they represent vast plains. Loess fields are dome-shaped rocks, consisting of particles 0.01-0.05 mm in size, they are porous

Cryogenic– rocks with negative temperatures in the presence of ice in cracks. Types: seasonal permafrost, permafrost.

Cryolithozones - where permafrost is developed.

Types of permafrost: Island (permafrost up to 25 m), not continuous (up to 100 m), continuous (yes 1000 m)

Relief caused by permafrost: 1. frost cracking of the soil (alternate freezing and thawing of the soil - slightly convex shape, surrounded by vegetation, dimensions up to 100 m or more)

2. Thermokarst- thawing and subsidence of the soil leads to the formation of depressions and basins (alsy (basins, up to several kilometers in diameter, up to 30 m deep)) 3. Soil swelling - an increase in the volume of water during freezing. (baijarahi - heaving mounds, an image of a combination of frost expansion and soil erosion by water and an image of a crack (up to several meters in height))

Suffusively-karst- groundwater activity.

Aeolian- Aeolian processes are associated with geological and geomorphological wind activity.

Corrosion - grinding, polishing of rocks with a wind flow containing rock particles.

Corazion niches, stone mushrooms, pillars - the most corrosive work is carried out by the wind flow in a layer of 1.5-2 m from the surface of the earth

Deflation is the blowing, dispersal, capture and transport of rock particles. During deflation, loose rock material is blown out and dispersed.

Biogeomorphological The processes of changing the Earth's surface as a result of the activity of living organisms are called biogeomorphological, and the relief created with the participation of plants and animals is called biogenic. These are mainly nano-, micro- and mesoforms of relief.

A grandiose process, carried out largely thanks to organisms, is sedimentation (for example, limestones, caustobiolites and other rocks).

Plants and animals also participate in a complex universal process - weathering of rocks, both as a result of direct impact on rocks and through the products of their vital activity. It is not for nothing that biological weathering is sometimes distinguished along with physical and chemical weathering.

Wind activity is one of the most important geological and relief-forming factors on the land surface. All processes caused by wind activity and the relief and shape deposits they create are called aeolian (Aeolus - god of the winds Greek mythology ). Aeolian processes occur throughout the entire landmass, but are most active in deserts, semi-deserts, and on the coasts of seas and oceans. This is facilitated by the optimal combination of conditions conducive to the development of aeolian processes: 1) the absence or sparseness of vegetation cover, which determines the presence of direct contact of the rocks composing the territory and atmospheric air flows; 2) frequent winds; 3) the presence of large volumes of loose material that can be moved by the wind. It should be noted that temperature weathering is of significant importance in the “supply” of clastic material, which is subsequently transported by the wind, in deserts (which, as is known, are characterized by significant daily temperature fluctuations). Aeolian processes also play a significant role in dry steppes, savannas, periglacial areas, and valleys large rivers and other open landscapes. Fine material carried by the wind can travel hundreds and even thousands of kilometers (it is enough to note that in large areas of the ocean floor the contribution of aeolian material reaches 50-70% or more).

The geological activity of wind consists of the processes of rock destruction, material transfer and accumulation, which are closely interrelated and occur simultaneously.

Destructive activity of wind

The destructive activity of wind consists of two processes - deflation and corrosion.

Deflation (from lat. "deflatio" - deflation) - the process of blowing and scattering particles of loose rocks by the wind. Small particles of pelitic, silty and sandy sizes are subject to deflation. There are areal and local deflation. Areal deflation results in uniform blowing of loose particles from large areas; The decrease in surface due to such deflation can reach 3 cm per year. The development of local deflation is determined by the characteristics of the movement of air flows and the nature of the relief. The formation of blowout basins is associated with the action of ascending vortex flows. As special type Local deflation is distinguished by furrow deflation. In cracks, narrow crevices or furrows, the wind force is greater, and loose material is blown out from there first. In particular, this type of deflation is associated with the deepening of road ruts: in China, in areas composed of loess, narrow canyons with a depth of a few tens of meters are formed in place of roads.

Corrasia (from lat. “corrado” - scrape, scrape off) is the process of mechanical abrasion of rocks by debris carried by the wind. It involves turning, grinding, and drilling rocks. Particles carried by the wind, hitting the surface of bedrock encountered along the way, act as a natural “abrasive tool”, producing strokes, grooves, niches and other characteristic shapes on their surface. During the process of such grinding, the formation of new fragmentary material also occurs, which is involved in the process of deflation (a rough analogy of such a process can be the action of an abrasive tool on an object - as a result of processing, the object changes shape, and the removed part turns into fine material being ground off). Thus, the processes of corrosion and deflation are interconnected and occur simultaneously.

Transport of material by wind

The transfer of material by wind can be carried out in the following forms: rolling, by jumping movements and in suspension.

Large grains of sand and, during storm and hurricane winds, pebbles and rubble move by rolling or sliding.
Through spasmodic movements (or saltation – from lat. "saltatio" - jump). In this way, grains of fine- and medium-grained sand (0.1-0.5 mm in size) move. In the process of saltation, a sand grain is lifted from the surface by a gust of wind (rising to a height of cm - tens of cm), describes a parabolic curve in the air, then, hitting the grains lying on the surface, is drawn into motion. In fact, the movement of the wind and the particles it carries is the movement of a wind-sand flow. The saturation of the flow with sand decreases with distance from the surface; sand grains rise to a height of more than 1 m only under very strong winds. The most important parameter determining the nature of the wind-sand flow is wind speed. To move fine-grained dry sand (with a particle size of 0.1-0.25 mm), a wind speed of about 4-5 m/sec is required, for coarse-grained sand with a particle diameter of 0.5-1 mm - 10-11 m/sec . Typically, sandy material is transported within deserts.
Moving in suspension is typical for dusty particles. Particles move in the air flow (at an altitude of up to 3-6 km) without falling to the surface until conditions change (wind speed, etc.). Silt and pelitic material under favorable conditions (a combination of dry air from arid regions and strong winds) can move thousands of kilometers. Dust raised to great heights during volcanic eruptions can be transported especially far. So the ashes of the Krakatoa volcano flew around during the 1883 eruption Earth and remained in the air for about three years, settling in different parts of the planet (sometimes in the form of “bloody rains”). Large particles are often transported by hurricanes and tornadoes.

Accumulative wind activity

The accumulative activity of wind consists in the accumulation of aeolian sediments, among which two genetic types are distinguished - aeolian sands and aeolian loess. In the modern era, these deposits are formed in deserts and on their periphery, but during the Quaternary glaciation they were actively formed in the zone framing the ice caps. Aeolian deposits arise primarily as a result of wind capture and transfer of more ancient accumulations (marine, river, lake, etc.) or the partial participation of products of mechanical destruction of other rocks. Depending on the degree and nature of aeolian processing of the source material, sand deposits are divided into undisplaced (winnowed) and displaced (blown). Winnowed sediments lie in close proximity to rocks (sands) due to the deposition of which they accumulated, and are represented mainly by sands. Inspired sediments deprived of spatial connection with parent rocks, they are characterized by enrichment in fine-grained material capable of moving over long distances, represented by loess.

Aeolian loess (German “Loss” from “lose” - loose, unsolid) - deposits composed of dusty particles, non-layered, and highly porous. The characteristic features of loess are the following.

• Fine-grained dusty composition. There are no particles larger than 0.25 mm or no more than 5%.
• High porosity – pore volume can reach 50-55%. This feature determines the ability of loess to collapse in large blocks and sag when moistened or under load (for example, the weight of buildings). Due to the looseness of the rocks, they are easily destroyed during deflation or under the influence of water flows (the famous “yellow” river - the Yellow River - has a specific color of water due to the transfer of a large volume of loess material).
• Occurrence in the form of cloak-like covers.
• Lack of layering and uniformity of composition.
• The presence of buried soil horizons in them. The study of the characteristics of pollen and fossil mollusks buried in loess indicates their formation under conditions of a cold glacial climate. Soil horizons, having deteriorated, contain signs of formation in warmer conditions. This feature made it possible to determine that a significant part of the loess arose during glacial periods in periglacial zones (and the soils buried in them - during the interglacial period).

Aeolian sands also have a number of specific features, among which the following should be noted.

• Good sorting of grains with a predominance of particles 0.1-0.25 mm in size.
• The matte surface of the grains, the presence of the so-called “desert tan” - a ferrous or manganese film on their surface.
• Presence in sediments windbreakers- rock fragments of two-, three-, and tetrahedral shapes, resulting from the grinding action of sand carried by the wind.
• Cross bedding with layer dip angles of about 30 0 .
• Lack of fauna and cement.

It should be added that, settling from the air, including together with raindrops and snow, dust particles are mixed with marine and continental sediments of different origins, without forming independent aeolian accumulations in such cases.

Aeolian landforms

Most common accumulative and accumulative-deflationary forms formed as a result of the movement and deposition of sand particles by wind, as well as developed (deflationary) forms, arising due to the blowing out of loose weathering products. The shape and size of accumulative and accumulative-deflationary formations depend on a combination of a number of factors: the nature and regime of winds, the amount of vegetation (preventing the free movement of sands), as well as the saturation of sand particles in the wind-sand flow, moistening of sands, the nature of the underlying surface, and some others. The dependence of sand relief forms on formation conditions is shown in the figure.

Aeolian forms are most widespread in deserts. The relief of deserts is characterized by the simultaneous presence of dynamic accumulative and deflationary-accumulative aeolian forms of different scales superimposed on each other.
The main element of the microrelief is aeolian ripple. As is known, between two parallel moving media with different densities and mobility (in this case, dry sand and air), the interface acquires a wave-like character. The undulation of the sand surface leads to the formation of moving ripples on its surface. The height of the ripple rollers is from millimeters to tens of centimeters, the rollers are asymmetrical - the windward slope is gentler. Massive rolling of sand grains occurs predominantly within just one ridge of ripples, starting on its windward slope and ending at the crest. The movement of ripples and “sand waves” is carried out due to the shedding of the leeward slope of the rollers.
Larger elements of the relief are shield-shaped accumulations of sand, formed in depressions of the relief or wind shadow. Subsequently, shield accumulations are rebuilt into dune relief forms - single and group dunes, then - into dune chains, dune ridges, etc.

Dunes- mobile accumulative-deflationary relief forms of deserts, which are large accumulations of sand, crescent-shaped in plan. A characteristic morphological feature of the dunes is their semi-lunar or crescent-shaped outline and the presence of asymmetrical slopes: a long gentle (5-14°) windward slope and a short steep (30-33°) leeward slope, turning into “horns” elongated in the wind. In this case, the “horns” are directed in the direction of the wind. The height of the dunes is usually a few meters, but can reach 100 m or more. The dunes are dynamic and change their shape depending on the direction and speed of the wind and the uniformity of the supply of a particular amount of sand.
The movement of sand along the dune profile in different parts of it is not the same. The following three zones can be distinguished.

1. The zone of fluttering, or deflation, which is characterized by the processes of separation of grains from the surface of the sand in the absence of their introduction. Here the removal of sand grains from the surface takes place.
2. Transfer and exchange area. At low wind speeds, intense movement of ripples from the deflation zone occurs; during strong winds - at the moment a stream of wind-sand flow hits the surface of the leeward slope, a redistribution of sand in size occurs (the larger one settles on the slope, the lighter one - carried or torn off upon impact - is involved in further movement).
3. Accumulation zone, where the accumulation of sand transported from the deflation zone occurs.

Longitudinal profile of the dune

1 - removal zone, 2 - transfer zone, 3 - accumulation zone, 4 - neutral zone, 5 - windward slope, 6 - shedding slope, 7 - ridge, 8 - dune height, 9 - path of maximum saturation of the wind-sand flow with sand.

A characteristic feature of the dune is the formation of a vortex behind the crest of the chain (in the “wind shadow”), leading to the emergence of an air flow opposite to the direction of the wind. Sand, blown by the wind from the crest of the dune or crumbling when the ripples reach the crest, falls into this vortex and settles on the slope. The presence of this aerodynamic feature determines the asymmetrical structure of the dune and its stability.
A more complex form of aeolian desert relief is the dune chain. The dune chain is a moving accumulation of sand in the form of a highly elongated asymmetrical wave-like shaft. Dune chains are usually arranged in parallel rows. This is due to the formation of two mutually perpendicular air flows during their formation: one, the main one, corresponds to the direction of the wind (it is perpendicular to the chain), the second, formed by reducing pressure during the formation of vortices in the accumulation zone, has a direction parallel to the chains. The long-term existence of dune forms perpendicular to the wind direction is possible only in the presence of two oppositely oriented directions of the prevailing winds (restraining the extension of the “horns” parallel to the wind). The presence of one dominant wind direction leads to the development of asymmetrical dunes and dune ridges. Their development is associated with the uneven distribution of wind flow energy, its “fluidity” (for example, associated with relief features).

Sandy landforms develop not only in deserts and semi-deserts, but also in non-desert areas - coastal zones of oceans, seas, large lakes, river valleys with weak vegetation development, on periglacial plains, where loose sandy deposits are also widespread. Within such landscapes there are developed dunes- mobile accumulative-deflationary sand forms of relief in non-desert areas. Unlike dunes developed in deserts, dunes have “horns” located on the windward side. The gentle slope faces the wind and has an inclination angle of 8-20°, the windward slope is 30-40°. Dunes can move in the direction of the prevailing wind at speeds of up to 10 m per year, depending on the mass of sand and wind speed. The evolution of dunes, under the dominance of one or similar wind directions, is expressed in a gradual transition from coastal or riverbed dune banks transverse to the wind, into arched, parabolic and hairpin-shaped forms. This morphological evolution is determined by the uneven movement of sand in its composition: the central part moves most actively, while the marginal parts moistened and fixed by vegetation move more slowly (which determines the orientation of the “horns” towards the wind). In areas with a convective wind regime, rounded swell-like dunes develop with blowing from the center to the periphery.

The main forms of sand relief associated with the wind regime (Fedrovich, 1983)


I- sand dunes of deserts. A.: trade wind type (with winds of the same or similar directions): 1 - sand shield; 2 - the same, with a funnel (embryonic dune); 3 - crescent-shaped symmetrical dune; 4 - asymmetrical dune; 5 - dune ridges longitudinal to the wind; 6 - complex longitudinal dune ridges (“whale backs”);
B - monsoon-breeze type (with winds of opposite directions): 7 - group dunes; 8 - simple dune chains; 9 - complex dunes and dune chains;
B - convection and interference types (with a system of uniform winds and with winds of transverse directions): 10 - circular dunes; 11 - the same, pyramidal; 12 - the same, crossed complex ones.
II- half-overgrown desert sands. A: 13 - bite braids; 14 - small beds; 15 - ridge sands; 16 - ridge-large-ridge sands;
B: 17 - ridge-hole sands; 18 - hole sands; 19 - rake-shaped transverse ridges; 20 - transverse ridges;
B: 21 - cellular sands; 22 - coarse sands; 23 - pyramidal sands; 24 - lattice ridges.
III- dune non-desert sands. A.: 25 - coastal ramparts; 26 - parabolic dunes; 27 - hairpin dunes; 28 - paired longitudinal dunes; 29 - complex parabolic dunes;
B: 30 - semicircular small dunes; 31 - the same, large; 32 - semicircular complex dunes;
B: 33 - small ring-shaped dunes; 34 - the same, large; 35 complex circular dunes.
The arrows show the prevailing wind directions.

Less common corrosive(more precisely deflationary-corrosive, since these processes act together) aeolian landforms, arising under the influence of dynamic wind impacts and, especially, under the influence of impacts of small particles carried by the wind in a wind-sand flow. The wind-sand flow moves in the ground layer (up to a height of 1.5 - 2 m), so the lower parts of obstacles standing in the way of the wind are most actively developed, which leads to the formation of characteristic aeolian mushrooms and cornices. When hard grains of sand get into cavities and cracks in rocks, they expand to form niches and caves. An important factor determining the characteristics of the corrosive relief is the difference in the strength of rocks, leading to their uneven destruction and the formation of bizarre shapes. The combination of these factors sometimes leads to the formation aeolian cities- areas of the desert with numerous rock remains, which, due to intense physical weathering and the mechanical action of wind-blown sand, take on bizarre shapes.

Corrosive forms in deserts: traces of corrasia in sandstones (Sinai Desert, Egypt) and aeolian fungus (Arbol de Piedra, Bolivia)

Video: Aeolian landforms and desert landscapes

Novosibirsk State University

Faculty of Geology and Geophysics

Department of General and Regional Geology

Vert Irina Vladimirovna

Course 1, group 054

COURSE WORK

Abstract topic:

EOLIAN PROCESSES

Scientific adviser:

LABEKINA IRINA ALEKSEEVNA

Reviewer (BREDIKHINA

OKSANA NIKOLAEVNA)

Novosibirsk

ANNOTATION

This course work contains materials on the topic “Aeolian processes”; the reasons for the process in question and its consequences are also outlined below. The work is written on the basis of a complex multi-level plan containing nine main points (including introduction, notes, conclusion and list of references) and twelve minor ones, including the goals and objectives of the research, as well as information about the objects and subjects of research. It consists of 21 pages, on which there are 2 figures (p. 8 and p. 12, respectively), 175 paragraphs and 945 lines, and there is also a large number of examples. At the end course work(on page 21) there is a list of all the literature used.

In the given course work the materials on a theme “Geological work of a wind” are assembled, also reasons of considered process and its consequences are stated below. The work is written on the basis of the complex multilevel plan containing nine basic items (including introduction, notes, conclusion and list of the used literature) and twelve minor, including purpose and research problem, and also item of information on objects and subjects of researches. It consists of 21 pages, on which 2 figures (page 8 and page 12 accordingly), 175 paragraphs and 945 lines are placed, and even in work there is a plenty of examples. At the end of course work (on page 21) there is a list of the used literature.

Before a perusal course I recommend to address to a TABLE of CONTENS, and then to the NOTE.

1. Notes (symbols)……………………………...4p.

2. Introduction…………………………………………….………………….4pp.

3. Formulation of the topic……………………………..………...………5pp.

4. Goals and objectives of the research……………………..…………………..6p.

5. Objects and subject of research……………..………...………….7pp.

5.1. Wind, types of winds…………………………..…………...……….…7pp.

5.2. Classification of deserts…………………………….….…………..8p.

5.2.1. Deflationary deserts………………………...…….….….……8pp.

5.2.2. Accumulative deserts……………………………………. 8 pages

6. Current knowledge in this area………….………………..10pp.

6.1. Geological work of wind……………………...………….……10pp.

6.1.1. Deflation and corruption………………………………….…..….11p.

6.1.2. Aeolian transportation…………………..…………………..12p.

6.1.3. Aeolian accumulation…………………….…..………………………p.

6.2. Weathering…………………………………….…..…………….14p.

6.2.1. Physical weathering……………………..……….………p.

6.2.2. Chemical weathering…………………..…....………….…17p.

6.2.3. Biogenic weathering………………………..………………p.

7. The place of this topic in the curricula and topics of the State Geological Physics of NSU and OIGGM SB RAS………………………………………………….…….19p.

8. Conclusion……………………………………………………………...20p.

9. List of references…………………………………………………………….20 pages.

1. Note.

The text contains abbreviations and symbols:

· Page (page)

· Rice. (drawing)

· ETC: ( the paragraph following this designation contains an example )

· All basic concepts and definitions are highlighted special font

Each point of the plan is highlighted large print, has a number corresponding to the number in the table of contents and is located on the page indicated in the table of contents.

2. Introduction.

Before writing about what is contained in my course work, I would like to tell you why I chose this particular topic. Looking through the proposed topics for the course work for the first time, I immediately drew attention to topic number 51. What attracted me to this topic was that all our lives we have been faced with the work of the wind, with aeolian processes, but few of us have ever thought about what are the causes of the wind, what is its activity and what significance does it have in our lives...

The wind has always been given great importance, the wind has always been a symbol of change and innovation. Even in folk sayings and in phraseological units, the wind was given not the last place: Throwing words to the wind, wind in the head, a windy person, and so you can continue for a very long time... So I wanted to know more about what always accompanies us...

And in general, I believe that the topic for the coursework should be chosen so that it is, first of all, of interest to the person writing the coursework. And secondly, it would be interesting and useful to those who will listen to it. I think that what I wrote about in my work is not only interesting, but also useful.

3. Formulation of the topic and problem.

The geological activity of wind is associated with the dynamic effect of air jets on rocks. It is expressed in the destruction, crushing of rocks, smoothing and polishing of their surface, transfer of small fragmentary material from one place to another, in its deposition on the surface of the Earth (continents and oceans) in an even layer, and then unloading this material in the form of hills and ridges on certain land areas. The geological work of wind is often called aeolian (named after the god of the winds - Aeolus - from the ancients Greek myths).

ETC:

Aeolian processes also include weathering. It is a process of change (destruction) of rocks and minerals due to their adaptation to the conditions of the earth's surface and consists of a change in the physical properties of minerals and rocks, mainly reduced to their mechanical destruction, loosening and change chemical properties under the influence of water, oxygen and carbon dioxide in the atmosphere and the vital activity of organisms.

Obruchev V.A. wrote the following about weathering: “So, little by little, from day to day, from year to year, from century to century, imperceptible forces work on the destruction of rocks, on their weathering. We don’t notice how they work, but their fruits works are visible everywhere: solid solid rock, which was initially cut only by thin cracks, turns out, thanks to weathering, to be more or less severely destroyed; immediately in heaps at the foot of the cliff or rolled down the slope, forming screes. The smooth surface of the rock became rough, corroded in places; in places there are potholes and cracks, in places there are black or rusty stains.”

The geological work of wind is significant and covers large areas, because deserts on Earth alone occupy 15-20 million km. Within continents, the wind acts directly on the surface earth's crust, destroying and moving rocks, forming aeolian deposits. In areas of seas and oceans this impact is indirect. The wind here forms waves, permanent or temporary currents, which in turn destroy rocks on the shores and move sediment at the bottom. We should not forget the essential importance of wind as a supplier of clastic material that forms a certain type of sedimentary rock on the bottom of seas and oceans.

The complex movements of air masses and their interactions are further complicated by the formation of giant air vortices, cyclones and anticyclones. Moving over the seas, cyclones cause huge waves and tear off spray from the water, resulting in a rotating column of water in the center. Cyclones have great destructive power. As a result of their activities, surges of water into river mouths are dangerous, especially in areas of high tides. The coincidence of surges and tides causes the water to rise to 15-20 meters or more. IN tropical zone During cyclones, quite heavy objects were thrown in the air over a considerable distance.

ETC: One of the destructive hurricanes was Inez, which raged in September-October 1966 in the Caribbean Sea. Its speed in the center was about 70 m/sec, and the pressure dropped to 695 mm.

4. Goals and objectives of research.

The wind carries out geological work in various parts of the Earth's surface, but since the force of the wind on the tops of mountains is much greater than in basins and lowlands, its activity is more noticeable there. The importance of wind activity is especially great in areas of dry climate, sharp daily and annual temperature fluctuations.

Aeolian activity, as a rule, brings harm to humans, since as a result of it, fertile lands are destroyed, buildings, transport communications, tracts of green space, etc. are destroyed.

ETC: A significant part of the modern Libyan Desert ( North Africa) 5-7 thousand years ago it was a fertile region. The sands turned this area into a desert. In Central Asia, on the banks of the Amu Darya, the city of Tartkul was located. Due to the intense erosion of coastal streets by river water, people left the city, and then for several years the city was covered with desert sand. Deflation in Ukraine has destroyed vast areas of crops. In buildings on the outskirts of deserts, due to corrosion, glass quickly becomes cloudy, houses become covered with scratches, and grooves appear on stone monuments; for example, the famous sphinx near Cairo in Egypt is covered with furrows.

The processes and landforms associated with the work of the wind are called aeolian in honor of the ancient Greek god Aeolus, the lord of the winds. These processes include:

wind carrying away the results of weathering;

grinding, gouging out the surface of rocks with solid particles carried by the wind;

transport of aeolian material and its accumulation.

These processes occur wherever there are loose, loose sediments, for example, on sandy river banks, but the work of the wind is most clearly visible in deserts - areas characterized by dry air and lack of vegetation. Rocks there are quickly destroyed due to strong temperature fluctuations (physical weathering). The wind acts in conjunction with weathering, carrying away its products and clearing the surface for further destruction. In some places, the desert surface is covered with a layer of large debris left in place after small particles were blown away. This layer protects the rocks from further destruction.

It happens that in the silent desert a traveler suddenly hears strange sounds. In ancient times, these places were called “singing sands”; they were feared, believing that spirits lured travelers to places where they could not escape. Later it was discovered that the sounds were made by grains of sand sliding along the surface of wet sand. The thinner the sliding sand, the finer the sound. The reason for the appearance of these sounds is electrical phenomena that occur in the sand during sliding. “Singing sands” exist not only in deserts, they are found along the banks of rivers and seas.

In deserts, the wind creates landforms such as dunes. These are sandy hills shaped like a crescent. Their height ranges from 5 to 200 meters. One slope of the dune is gentle and long. It always faces the direction from which the wind blows. The other slope is steep, with a sharp ridge, curved in the form of an arc, and it faces in the direction where the wind blows. Dunes can move under the influence of the wind. This is why they are dangerous, as they can fall asleep at home. This happens because the wind blows sand from the gentle slope, which rolls down the steep slope, and the dune moves at speeds of up to hundreds of meters per year. The fight against dunes involves securing the sand with trees or shrubs. As individual dunes grow, they are connected into dune chains. There are many dunes in the deserts of Central Asia and the Sahara.

In places where there is not enough free sand for the formation of dunes and there is enough vegetation, hummocky or cumulus sands appear: motionless mounds fixed by vegetation from 2 to 8 meters high.

Dunes form on the sandy shores of seas, and less often of rivers and lakes. Unlike a dune, a dune has a convex shape, not a gentle slope, but a steep one. The windward slope is gentle, the leeward slope is steeper. The height of the dunes can reach 30 m or more. On the coast of the Baltic Sea there are dunes 60 m high, and in France the height of the dunes reaches 100 m. They move at a speed of up to 20 meters per year, usually forming a chain of sand hills parallel to the coastline at some distance from the water. To stop the movement of sand, which causes irreparable damage by filling up arable lands, forests, and villages, bushes are planted on the beach, from where the wind draws material for the construction of dunes. The dunes are also stabilized by planting pine trees.

The relief-forming activity of wind is noticeable not only in sandy deserts, but also in rocky ones. Here, ledges of hard rocks, individual rocks, cliffs under the influence of wind and with the participation of weathering form bizarre shapes: cornices, columns, pillars.

In addition to dunes, dunes, and hummocky sands, aeolian loess also belongs to aeolian deposits.