In military affairs terrain understand the area of ​​​​the earth's surface on which to conduct hostilities. The unevenness of the earth's surface is called terrain, and all objects located on it, created by nature or human labor (rivers, settlements, roads, etc.) - local items.

The relief and local objects are the main topographical elements of the terrain that affect the organization and conduct of combat, the use of military equipment in combat, the conditions for observation, firing, orientation, camouflage and maneuverability, i.e., determining its tactical properties.

A topographic map is an accurate representation of all the most tactically important elements of the terrain, plotted in a mutually exact arrangement relative to each other. It makes it possible to explore any territory in a relatively short time. Preliminary study of the terrain and decision-making for the performance of a particular combat mission by a subunit (unit, formation) is usually carried out on a map, and then refined on the ground.

The terrain, influencing combat operations, in one case can contribute to the success of the troops, and in the other have a negative effect. Combat practice convincingly shows that one and the same terrain can give more advantages to those who study it better and use it more skillfully.

According to the nature of the relief, the area is divided into flat, hilly and mountainous.

flat terrain characterized by small (up to 25 m) relative elevations and a relatively small (up to 2 °) steepness of slopes. Absolute heights are usually small (up to 300 m) (Fig. 1).

Rice. 1. Flat, open, slightly rugged terrain

The tactical properties of flat terrain depend mainly on the soil and vegetation cover and on the degree of ruggedness. Clayey, loamy, sandy loamy, peaty soils allow the unhindered movement of military equipment in dry weather and significantly impede movement during the rainy season, spring and autumn thaws. It can be indented by riverbeds, ravines and gullies, have many lakes and swamps, which significantly limit the ability to maneuver troops and reduce the rate of advance (Fig. 2).

Flat terrain is usually more favorable for the organization and conduct of an offensive and less favorable for defense.

Rice. 2. Plain lake-forest closed rugged terrain

hilly area characterized by a wavy nature of the earth's surface, forming irregularities (hills) with absolute heights up to 500 m, relative elevations of 25-200 m and a prevailing steepness of 2-3 ° (Fig. 3, 4). The hills are usually composed of hard rocks, their tops and slopes are covered with a thick layer of loose rocks. The depressions between the hills are wide, flat or closed basins.

Rice. 3. Hilly semi-closed rugged terrain
Rice. 4. Hilly ravine-beam semi-closed rugged terrain

Hilly terrain provides for the movement and deployment of troops hidden from enemy ground observation, makes it easier to choose places for firing positions of missile troops and artillery, and provides good conditions for concentrating troops and military equipment. In general, it is favorable both for the offensive and for defense.

Mountain landscape represents areas of the earth's surface that are significantly elevated above the surrounding area (having absolute heights of 500 m or more) (Fig. 5). It is distinguished by a complex and varied relief, specific natural conditions. The main landforms are mountains and mountain ranges with steep slopes, often turning into rocks and rocky cliffs, as well as hollows and gorges located between mountain ranges. The mountainous area is characterized by a sharp rugged terrain, the presence of hard-to-reach areas, a sparse network of roads, a limited number of settlements, a rapid flow of rivers with sharp fluctuations in water levels, a variety of climatic conditions, and a predominance of rocky soils.

Combat operations in mountainous areas are considered as operations in special conditions. Troops often have to use mountain passes; observation and firing, orientation and target designation are difficult, at the same time it contributes to the secrecy of the location and movement of troops, facilitates the setting up of ambushes and engineering barriers, and the organization of camouflage.

Rice. 5. Mountainous rugged terrain

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Relief- a set of irregularities of the earth's surface.

The relief is composed of positive (convex) and negative (concave) shapes. The largest negative forms relief on Earth - the depressions of the oceans, positive - continents. These are landforms of the first order. Landforms second order - mountains and plains (both on land and at the bottom of the oceans). The surface of mountains and plains has a complex relief, consisting of smaller forms.

Morphostructures- large elements of the relief of land, the bottom of the oceans and seas, the leading role in the formation of which belongs to endogenous processes . The largest irregularities on the Earth's surface form protrusions of the continents and depressions of the oceans. The largest land relief elements are flat-platform and mountainous areas.

Plain-platform areas include flat parts of ancient and young platforms and occupy about 64% of the land area. Among the flat-platform areas there are low , with absolute heights of 100-300 m (East European, West Siberian, Turan, North American plains), and high , raised by the latest movements of the crust to a height of 400-1000 m (Central Siberian Plateau, African-Arabian, Hindustan, significant parts of the Australian and South American plain regions).

mountainous areas occupy about 36% of the land area.

Underwater margin of the mainland (about 14% of the Earth's surface) includes a shallow, flat, as a whole, continental shelf (shelf), a continental slope, and a continental foot located at depths from 2500 to 6000 m. The continental slope and the continental foot separate the protrusions of the continents, formed by the combination of land and shelf, from the main part of the ocean floor, called the ocean floor.

Island arc zone - transitional zone of the ocean bed. The actual ocean bed (about 40% of the Earth's surface) is mostly occupied by deep-water (average depth 3-4 thousand m) plains, which correspond to oceanic platforms.

Morphosculptures- elements of the relief of the earth's surface, in the formation of which the leading role belongs to exogenous processes . The work of rivers and temporary streams plays the greatest role in the formation of morphosculptures. They create widespread fluvial (erosion and accumulative) forms (river valleys, gullies, ravines, etc.). Glacial forms are widespread due to the activity of modern and ancient glaciers, especially the sheet type (northern part of Eurasia and North America). They are represented by valleys of mitrogs, "ram's foreheads" and "curly" rocks, moraine ridges, eskers, etc. In the vast territories of Asia and North America, where permafrost rock strata are widespread, various forms of permafrost (cryogenic) relief are developed.

The most important landforms.

The largest landforms are the protrusions of the continents and the depressions of the oceans. Their distribution depends on the presence of a granite layer in the earth's crust.

The main landforms of land are the mountains and plains . Approximately 60% of the land is occupied plains- vast areas of the earth's surface with relatively small (up to 200 m) elevation fluctuations. According to the absolute height, the plains are divided into lowlands (height 0-200 m), hills (200-500 m) and plateaus (above 500 m). By the nature of the surface - flat, hilly, stepped.

Table “Relief and landforms. Plains.

The mountains- elevations of the earth's surface (more than 200 m) with clearly defined slopes, soles, peaks. In appearance, the mountains are divided into mountain ranges, chains, ridges and mountainous countries. Separate mountains are rare, representing either volcanoes or the remains of ancient destroyed mountains. Morphological mountain elements are: base (sole); slopes; peak or ridge (near ridges).

sole of the mountain- this is the border between its slopes and the surrounding area, and it is expressed quite clearly. With a gradual transition from the plains to the mountains, a strip is distinguished, which is called the foothills.

slopes occupy most of the surface of the mountains and are extremely diverse in appearance and steepness.

Vertex- the highest point of the mountain (mountain ranges), the pointed peak of the mountain - the peak.

Mountain countries(mountain systems) - large mountain structures, which consist of mountain ranges - linearly elongated mountain uplifts intersecting with slopes. The points of connection and intersection of mountain ranges form mountain nodes. These are usually the highest parts of mountainous countries. The depression between two ridges is called a mountain valley.

uplands- sections of mountainous countries, consisting of heavily destroyed ridges and high plains covered with destruction products.

Table “Relief and landforms. The mountains"

Mountains are divided into low (up to 1000 m), medium-high (1000-2000 m), high (more than 2000 m). According to the structure, folded, folded-block and blocky mountains are distinguished. By geomorphological age, young, rejuvenated and revived mountains are distinguished. On land, mountains of tectonic origin predominate, in the oceans - volcanic.

Volcano(from Latin vulcanus - fire, flame) - a geological formation that occurs above channels and cracks in the earth's crust, through which lava, ash, combustible gases, water vapor and rock fragments erupt onto the earth's surface. Allocate active, dormant andextinct volcanoes. The volcano is made up of four main parts : magma chamber, vent, cone and crater. There are about 600 volcanoes all over the world. Most of them are found along plate boundaries, where red-hot magma rises from the Earth's interior and erupts to the surface.

SLOPE STEEPENESS

terrain called a set of irregularities of the earth's surface.

Depending on the nature of the relief, the terrain is divided into flat, hilly and mountainous. The flat terrain has mild forms or almost no irregularities at all; hilly is characterized by alternation of relatively small elevations and depressions; mountainous is an alternation of elevations over 500 m above sea level, separated by valleys.

Of the variety of landforms, the most characteristic ones can be distinguished (Fig. 12).

Mountain(hill, height, hill) is a cone-shaped relief form towering above the surrounding area, the highest point of which is called the peak (3, 7, 12). The top in the form of a platform is called a plateau, the peak of a pointed shape is called a peak. The lateral surface of the mountain consists of slopes, the line of their confluence with the surrounding area is the sole, or base, of the mountain.

Rice. 12. Characteristic landforms:

1 - hollow; 2 - ridge; 3,7,12 - peaks; 4 - watershed; 5.9 - saddles; 6 - thalweg; 8 - river; 10 - break; eleven -

Basin or hollow,- This is a recess in the form of a bowl. The lowest point of the basin is the bottom. Its lateral surface consists of slopes, the line of their confluence with the surrounding area is called the edge.

Ridge 2 - this is a hill, gradually lowering in one direction and having two steep slopes, called slopes. The axis of the ridge between the two slopes is called the watershed line or watershed 4.

dell 1 - this is an elongated depression of the terrain, gradually lowering in one direction. The axis of the hollow between two slopes is called a weir line or thalweg 6. The varieties of the hollow are : valley- a wide hollow with gentle slopes, as well as ravine- a narrow hollow with almost steep slopes (cliffs 10) . The initial stage of a ravine is a ravine. A ravine overgrown with grass and shrubs is called beam. Sites sometimes located along the slopes of hollows, having the form of a ledge or steps with an almost horizontal surface, are called terraces 11.

Saddles 5, 9 are the low parts of the terrain between the two peaks. Roads often pass through saddles in the mountains; in this case the saddle is called pass.

The top of the mountain, the bottom of the basin and the lowest point of the saddle are characteristic points of the relief. The watershed and thalweg are characteristic lines of relief. The characteristic points and lines of the relief facilitate the recognition of its individual forms on the ground and their depiction on the map and plan.

The method of depicting the relief on maps and plans should make it possible to judge the direction and steepness of the slopes, as well as determine the marks of points in the terrain. However, it must be visible. There are various ways of depicting relief: perspective, shading with lines of different thicknesses, color wash(mountains are brown, hollows are green), horizontal. From an engineering point of view, the most advanced methods of depicting the relief are horizontals in combination with the signature of the marks of characteristic points (Fig. 13) and digital.

Horizontal A line on a map that connects points of equal elevation. If we imagine a section of the Earth's surface by a horizontal (level) surface R 0 , then the line of intersection of these surfaces, projected orthogonally onto a plane and reduced to a size on the scale of a map or plan, will be a horizontal line. If the surface R 0 located at a height H from the level surface, taken as the origin of the absolute heights, then any point on this horizontal line will have an absolute elevation equal to H. The image in the relief contours of the entire area of ​​​​the terrain can be obtained as a result of the section of the surface of this area by a number of horizontal planes R 1 , R 2 , … R n , located at the same distance from each other. As a result, contour lines with marks are obtained on the map H + h, H + 2h etc.

Distance h between secant horizontal planes is called relief section height. Its value is indicated on a map or plan under a linear scale. Depending on the scale of the map and the nature of the depicted relief, the height of the section is different.

The distance between contour lines on a map or plan is called mortgage. The greater the laying, the less the steepness of the slope on the ground, and vice versa.

Rice. 13. Image of the terrain with contour lines

Contour property: contour lines never intersect, with the exception of an overhanging cliff, natural and artificial funnels, narrow ravines, steep cliffs, which are not displayed by contour lines, but are indicated by conventional signs; horizontal lines are continuous closed lines that can only end at the border of a plan or map; the thicker the horizontal, the steeper the terrain depicted, and vice versa.

The main relief forms are depicted by horizontal lines as follows (Fig. 14).

Images of the mountain and the basin (see Fig. 14, a, b), as well as a ridge and a hollow (see Fig. 14, c, g) are similar to each other. To distinguish them from each other, the direction of the slope is indicated at the horizontal. On some horizontal lines, marks of characteristic points are signed, and so that the top of the numbers is directed towards the rise of the slope.

Rice. 14. Image by contour lines of characteristic

landforms:

a - mountain; b - basin; c - ridge; G- hollow; d- saddle;

1 - peak; 2 - bottom; 3 - watershed; 4 - thalweg

If, at a given height of the relief section, some of its characteristic features cannot be expressed, then additional semi- and a quarter of the horizontal are drawn, respectively, through half or a quarter of the accepted height of the relief section. Additional horizontals are shown with dotted lines.

To make it easier to read the contour lines on the map, some of them are thickened. With a section height of 1, 5, 10, and 20 m, every fifth horizontal line is thickened with marks that are multiples of 5, 10, 25, 50 m, respectively. With a section height of 2.5 m, every fourth horizontal line is thickened with marks that are multiples of 10 m.

The steepness of the slopes. The steepness of the slope can be judged by the magnitude of the deposits on the map. The smaller the laying (distance between horizontals), the steeper the slope. To characterize the steepness of the slope on the ground, the angle of inclination ν is used. Vertical angle called the angle enclosed between the line of the terrain and its horizontal laying. The angle ν can vary from 0º for horizontal lines to ± 90º for vertical lines. The greater the angle of inclination, the steeper the slope.

Landform types and their origin

Depending on the length (size) and the predominance of certain forms of relief, types of relief are distinguished : flat, hilly and mountainous terrains.

Forms and types of relief are, as mentioned above, the result of geological processes, they are composed of certain rocks and are subdivided according to their origin depending on the predominant factor - the force that caused their formation.

The forms and types of relief caused by the activity of endogenous forces, i.e., formed due to the movements of the earth's crust and lithosphere (vertical or oscillatory, horizontal or mountain-forming) and the accompanying magmatism and metamorphism, are called tectonic forms . These forms and types include the largest landforms: macro -, megareliefplanetaryrelief , arising and lying on geological structures of global and largest sizes. Builders erect various structures, mainly on land (continents), within which platforms and mountain-folded areas with smaller structures are distinguished. Therefore, we will consider below the types of relief characteristic of the continents. They, like the geological structures or the tectonics of the Earth, seem to be constant over a large span of geological time (thousands and hundreds of thousands of years).

Landforms created by endogenous processes change under the influence of exogenous forces that occur on the surface of the Earth under the influence of external energy sources (solar radiation, temperature fluctuations, the movement and composition of water and wind, living organisms, including humans). The listed energy sources act and change constantly, the relief forms they form are unstable and actively change their outlines in time. Among the exogenous landforms, the forms that arose due to the destructive and creative activity of exogenous processes stand out most clearly. They are very dynamic in their outlines and can noticeably change before the eyes of one generation of people. Other exogenous processes can develop within them: landslides, landslides, etc. Accumulative landforms arise with a decrease in the strength of the exogenous factor and, accordingly, the accumulation of rock destruction products - erosion and denudation by water and wind. Accumulative river terraces and floodplains, dunes and dunes are formed, composed of the corresponding types of continental
deposits (Table 20).

The main types of relief are flat, hilly and mountainous.

The flat relief is a vast area of ​​land with a flat

or a slightly undulating surface, within which the height fluctuations do not exceed 0 ... 200 m.

Among the plains, their groups are distinguished depending on:

- the positions above the sea level of the plain are negative (hollows, depressions) as the Caspian lowland, low (up to 200 m) - West Siberian lowland, elevated (200 ... 500 m) - Russian plain and plateau (more than 500 m) - Central Siberian plateau;

– depths and degree of dissection of the relief (assessment is made by elevation fluctuations over 2 km): weakly dissected (altitude fluctuations up to 10 m), finely dissected (altitude fluctuations up to 25 m), roughly dissected (altitude fluctuations up to 200 m);

- from the shape of the earth's surface: horizontal, inclined, concave and convex.

Absolute marks and dissection of the relief are a consequence (result), first of all, of the latest (Neogene-Quaternary) vertical movements associated with horizontal movements. Plains by origin: structural, accumulative and sculptural. Structural (primary, platform) plains formed on the site of platform sections of the earth's crust. They have a cover of calmly occurring layers of sedimentary or conformable bodies of igneous rocks (Caspian, West Siberian lowlands, Central Siberian table plain).

Accumulative plains have not only a platform sedimentary cover of almost horizontal marine deposits, but also continental - alluvial, glacial moraine, eolian and other deposits that arose due to exogenous processes. For example, Quaternary glacial deposits are very widespread on the East European Plain: moraine , fluvioglacial or limnic, which have a large thickness - tens to hundreds of meters. These deposits are dominated by alternating layers of sands and clays that form various hills and ridges called kams. , drumlinamiiosis. Within the boundaries of such landforms and deposits, builders carry out their activities, which must take into account the possibility of current exogenous processes occurring in such areas of the earth's surface, primarily landslides and water erosion. The East European Plain is classified as primary (on a platform cover). In the foothills and intermountain troughs (on a folded basement), sloping plains arise due to the accumulation of alluvial, deluvial-proluvial, and sometimes mudflow deposits.

Sculptural plains arise, as a rule, at the site of the destruction of ancient mountains, the leveling of the primary surface by the processes of denudation and abrasion. Abrasive plains are formed as a result of the destruction of coasts by sea waves. A denudation plain is a land area with a folded basement close to the earth's surface, i.e. outcropping of intrusive, metamorphic and sedimentary rocks, crumpled into folds and penetrated by various faults. The most striking example is the - the Ural plain, located to the east of the Ilmensky and Cherry mountains and the spurs of the Uraltau ridge, and occupying most of the territory of the Chelyabinsk region. It was formed during the Meso-Cenozoic due to the destruction of the Paleozoic Ural Mountains, the denudation of terrigenous deposits, as well as the abrasion activity of the West Siberian Sea, into which all clastic sediments were carried. Since the Trans-Ural plain was formed due to two most important exogenous processes, it is more correct to call it abrasion-denudation. The Kazakh uplands also belong to the denudation plains.

The hilly relief is characterized by the alternation of uplands with relative heights of no more than 200 m and lower areas in the form of hollows. The mountain relief is an alternation of large elevations in the form of mountains and ridges with a height of more than 200 m and depressions in the form of valleys, depressions and hollows. Depending on the absolute marks and the relative excess of the length by 2 km, mountainous reliefs are divided into high, medium-altitude and low. High mountains have absolute marks of more than 2000 m with a relative excess of 1000 m along lines perpendicular to the direction of river valleys. Medium-altitude mountains have absolute marks of 700 ... 2000 m and a relative incision depth of 500 ... 700 m. Low mountains have absolute marks of 700 ... 800 m and a dissection depth of 150 ... 450 m. The slopes are usually gentle. By origin, tectonic, volcanic and erosional

Tectonic mountains were formed as a result of complex tectonic: (horizontal and related vertical movements). They occupy most of the territories of the Cenozoic mountain-fold regions (the mountains of Kamchatka, Sakhalin, the Caucasus), as well as certain territories of ancient mountain-fold regions. At the base of the Southern Urals lies the Ural Paleozoic mountain-folded region, the mountains were preserved only to the west of the Trans-Ural plain, where individual blocks of the earth's crust as a result of the latest and modern vertical movements had the highest rates (up to 8 mm / year) and amplitudes (up to 1000 m) of uplifts. The mountains that were revived due to the uplift of individual blocks of folded areas in the Neogene-Quaternary time are classified as blocky mountains.

Volcanic mountains arose as a result of volcanic activity and were preserved in areas of Alpine (Cenozoic) folding, as in Kamchatka, in the Alps, or in the zones of modern mid-ocean ridges and rift zones, as Mt. Kilimanjaro.

Erosive mountains are formed as a result of the erosional dissection of ancient structural and accumulative plains due to Neogene-Quaternary uplifts of these blocks above the erosion base. An example of such mountains is the Putorana Plateau (marks up to 1700 m) on the Central Siberian Plateau.



The outline of a section of the earth's surface, including a set of land irregularities (elevations and depressions), as well as the ocean and seabed, is called terrain . The name of the term "relief" is of French origin from "relevo" - I raise.

The terrain is very varied.
The most characteristic landforms are:

Mountain - elevation on the earth's surface in the form of a dome or cone. The mountain has a top, a sole, slopes.
The slopes are gentle and steep. If the slope immediately turns from smooth to steep, it is called a cliff. A very steep cliff is called a cliff.

Basin - a recess on the earth's surface, closed on all sides. Figuratively, one can imagine the hollow as an element of the relief of the earth's surface, opposite to the mountain.
In the basin, slopes (or sides), as well as the bottom, are distinguished.

dell - a hollow of a zholoboobrazny form. In the hollow, also, slopes and bottom are distinguished. The line drawn along the deepest part of the hollow is called catchment line .
The narrow valley is called ravine (in the mountains - gorge ).

Ridge - the relief form, opposite to the hollow, represents an elevated part of the relief, usually elongated, having side slopes.
The upper part of the ridge, drawn along its length, is called watershed line .



Saddle - lowered terrain between two adjacent ridges. Usually a saddle is the beginning of two hollows, spreading in opposite directions from it.
In mountainous areas, saddles are usually crossed by passes - communication routes between mountain ranges, along which roads and trails are laid.

Plain - low-lying terrain with flat terrain. If the height of the plain above sea level does not exceed 200 m, it is called lowlands . A plain located at an altitude of more than 200 m above sea level is called plateau .

To solve many problems of engineering construction, military affairs, and others, it is necessary to have a reliable idea of ​​the relief of a given area. Projecting points of the earth's surface onto a horizontal plane makes it possible to study the distance between objects on this surface with a certain degree of error, but does not give an idea of ​​its relief.
In order for a topographic map or plan to meet the requirements of practical tasks, it is necessary to put on them the designation of irregularities in the displayed area, i.e. relief. To solve this problem, various leveling methods are involved, the results of which are then applied to the graphic image of the site.

Over the long history of the development of cartography, a variety of methods have been used to depict the terrain on flat maps and plans. The most widely used are three methods of drawing relief on a map - strokes, hillshade and horizontal lines. The method of drawing a relief on a plane using strokes has not stood the test of time, and is not currently used, therefore, the methods of horizontal lines and hillshade are usually used to depict the relief on topographic maps and plans.
You can learn more about how terrain elements are depicted on maps in the next article.