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Lesson questions:
1. Types and forms of terrain. The essence of the image of the relief on the maps by contour lines. Types of horizontals. Image by contour lines of typical landforms.
1.1 Types and forms of terrain.
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 display of all the most tactically important elements of the terrain, plotted in a mutually exact location 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).
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 marshes, 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.
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.
Hilly terrain provides for the movement and deployment of troops hidden from enemy ground observation, facilitates the choice of locations for firing positions of missile troops and artillery, and provides good conditions for the concentration of 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, 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.
1.2 The essence of the image of the relief on maps by contour lines.
The relief is the most important element of the terrain, which determines its tactical properties.
The image of the relief on topographic maps gives a complete and sufficiently detailed idea of the irregularities of the earth's surface, the shape and relative position, elevations and absolute heights of terrain points, the prevailing steepness and length of slopes.
1.3 Types of contour lines.
Horizontal- a closed curved line on the map, which corresponds to a contour on the ground, all points of which are located at the same height above sea level.
There are the following horizontal lines:
- main(solid) - relief section corresponding to the height;
- thickened - every fifth main horizontal; stands out for ease of reading the relief;
- additional horizontals(semi-horizontals) - are drawn by a broken line at the height of the relief section equal to half of the main one;
- auxiliary - are depicted as short dashed thin lines, at an arbitrary height.
Distance between two adjacent main contour lines in height are called the height of the relief section. The height of the relief section is signed on each sheet of the map under its scale. For example: "Solid contours are drawn through 10 meters."
To facilitate the calculation of contour lines when determining the heights of points on the map, all solid contour lines corresponding to the fifth multiple of the height of the section are drawn thickened and a number indicating the height above sea level is put on it.
In order to quickly determine the nature of surface irregularities on maps when reading a map, special slope direction indicators are used - berghashes- in the form of short dashes placed on the horizontals (perpendicular to them) in the direction of the slopes. They are placed on the bends of contour lines in the most characteristic places, mainly at the tops of saddles or at the bottom of basins.
Additional contours(semi-horizontals) are used to display the characteristic forms and details of the relief (bends of slopes, peaks, saddles, etc.), if they are not expressed by the main horizontals. In addition, they are used to depict flat areas, when the laying between the main contours is very large (more than 3 - 4 cm on the map).
Auxiliary horizontals used to depict individual details of the relief (saucers in the steppe regions, depressions, individual hillocks on flat terrain), which are not transmitted by the main or additional horizontals.
1.4 Depiction by contour lines of typical landforms.
The relief on topographic maps is depicted by curved closed lines connecting points of the terrain that have the same height above the level surface, taken as the origin of the heights. Such lines are called horizontal lines. The image of the relief with contour lines is supplemented by labels of absolute heights, characteristic points of the terrain, some contour lines, as well as numerical characteristics of relief details - height, depth or width (Fig. 7).
Some typical forms of terrain on the maps are displayed not only by the main, but also by additional and auxiliary contour lines (Fig. 8).
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Rice. 8. Image of typical landforms |
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2. Determination on the map of absolute heights and relative elevations of terrain points, ascents and descents, steepness of slopes.
2.1. Determination on the map of absolute heights and relative elevations of terrain points
2.2. Definition on the map of ascents and descents on the route.
Rice. ten. Definition on the map of ascents and descents on the route of movement (route profile).
Rice. eleven. Determination on the map of the steepness of the slopes |
Profile- a drawing depicting a section of the terrain with a vertical plane.
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2.3. Determination on the map of the steepness of the slopes.
The steepness of the slope on the map is determined by the location - the distance between two adjacent main or thickened horizontals; the smaller the laying, the steeper the slope \.
To determine the steepness of the slope, it is necessary to measure the distance between the horizontals with a compass, find the corresponding segment on the laying chart and read the number of degrees (Fig. 11).
On steep slopes, this distance is measured between thickened contours and the steepness of the slope is determined from the graph on the right.
3. Conventional signs of relief elements that are not expressed by contour lines.
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Ice cliffs (barriers) and outcrops of fossil ice (8 - height of the cliff in meters) |
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Sod ledges (edges) that are not expressed by horizontal lines |
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Shafts coastal, historical, etc., not expressed by contour lines (3 - height in meters) |
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1) Dry channels in one line (less than 5 m wide); |
Height marks |
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Command Height Marks |
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Landmark elevations |
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Main passes, marks of their heights and duration |
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Passes, marks of their heights and duration |
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Karst and thermokarst sinkholes not expressed on the map scale |
Pits that are not expressed on the scale of the map |
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Pits expressed in map scale |
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Rocks-outliers that have a landmark value (10-height in meters) |
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Rocks-outliers that do not have a landmark value |
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Dikes and other narrow, steeply walled hard rock ridges (5 - height of the ridge in meters) |
Mud volcano craters |
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Volcanic craters not expressed on the map scale |
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Mounds and mounds that are not expressed on the scale of the map |
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Mounds and mounds, expressed on the scale of the map (5 - height in meters) |
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Clusters of stones |
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Separately lying stones (3 - height in meters) |
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Entrances to caves and grottoes |
Abstracts
Military topography
military ecology
Military Medical Training
Engineering training
fire training
Fundamentals of external and internal ballistics. Hand grenades. Grenade launchers and rocket-propelled grenades.
Relief is the shape that the earth's surface has. The earth's relief is prone to dynamic changes. Small relief forms can change quite quickly, changes in larger ones occur over centuries.
The concept of the relief of the Earth
The relief of the Earth can change under the influence of various factors, in particular volcanic eruptions and earthquakes. Such factors are called endogenous. The destructive effect on the relief of wind, water, as well as flora and fauna is called exogenous impact.
In addition to these factors, human activity, its active economic intervention in the bowels, has a significant impact on the earth's relief. However, the anthropogenic factor cannot affect cardinal changes in the relief structure.
The main landforms of the Earth
The relief of the earth's surface is expressed in four forms: plains, highlands, shelves and mountains. Plains- the most stable areas of the earth's surface. On flat surfaces, the possibilities for changing the relief under the influence of various factors are minimal.
Plains include lowlands (up to 200 m above sea level), highlands (200-500m), plateaus (more than 500m).
The mountains are areas of land that rise to a height of more than 600m above sea level. Mountains are made up of peaks and steep slopes. Mountains can form highlands and ridges, which form a slight difference in elevation levels.
uplands are a system of mountain ranges, individual mountains and small valleys. The most famous highlands: Tien Shan, Pamir, Cordillera.
Shelf- This is a form of relief that is inherent exclusively in the bottom of the world's oceans. The shelf is a collection of vast areas of the seabed, often located along the coast.
Age of relief forms
Many factors influence the external characteristics of the earth's relief. One of them is the age of the Earth's relief. Despite the fact that relief forms belong to the category of inanimate nature, from the moment of their appearance they go through several evolutionary factors that can be identified with human life.
The age of relief forms is most clearly seen in mountain peaks. Young mountains are usually high and constantly in the process of dynamic growth. After the growth stage stops, the process of mountain aging begins.
Over the years, mountain systems begin to slowly lose their height - the slopes become gentle, they are covered with forest thickets. Mountain rivers lose their speed and turn into calm reservoirs. A few centuries after the cessation of mountain growth, mountain rivers can disappear altogether, leaving behind only wide valleys.
Relative elevation differences gradually begin to decrease. At this moment, the process of the disappearance of the mountains starts. Territories that used to have mountain peaks can turn into plateaus.
Elements and landforms
EARTH RELIEF
The earth's surface - the upper boundary of the earth's crust and lithosphere, has a complex relief in the form of various irregularities: elevations, plains and depressions. Certain combinations of forms of the earth's surface, regularly repeated over vast spaces, having a similar origin, geological structure and the same type of history of development, are called relief. The science that studies the relief, its origin and development - geomorphology .
In geomorphology, elements and forms of relief, the processes of their formation and patterns of placement are considered. The modern relief of the Earth is an external expression of the internal structure of one or another section of the earth's crust, complicated by the latest and modern tectonic movements (endogenous processes), as well as exogenous processes. Thus, the relief is a "function" of three components: geological structures, recent and modern movements, as well as exogenous processes that have taken place and are taking place on a given area of the earth's surface. It is in a state of continuous change, the speed of which is determined primarily by the speed of geological processes. Geomorphology is a science located at the intersection of geography and geology. The first is engaged in a more detailed study of the external forms of relief, and the second - the internal structure of certain forms and explains their origin.
The relief is of great importance for understanding geographical patterns, the flow of exogenous geological processes, as well as applied significance for construction.
Elements and landforms
Terrain features include surfaces, lines, and points. Surfaces are divided into horizontal, inclined, concave, convex and complex and form a relief shape. The intersection of relief surfaces occurs along lines or points. Divide lines are different , water - drain , plantar ridges . The highest height of the site in a given area is called the top, the lowest point of depressions in the relief is called the bottom. The bottom of the lowering of the crests of the ridges is called the pass points. Relief forms are composed of various combinations of elements.
Depending on the location of the relief forms in relation to the horizon plane, positive (convex in relation to the horizon plane) and negative (concave) relief forms are distinguished.
Positive landforms include:
–continents – large areas of the earth's surface, protruding above the level of the World Ocean, are based on the continental type of the earth's crust;
– highlands – a vast upland consisting of a system of mountain ranges and
peaks of the Pamirs);
- mountain range - an elongated hill with relative elevations of more than 200 m and with steep, often rocky slopes, for example, ridge. Zyuratkul;
-mountain ridge - a low mountain range with more gentle slopes and a flat top, for example, the Donetsk ridge;
-mountain - an isolated hill with a height of more than 200 m, with steep slopes and a line of maximum heights, called a ridge, for example, Golaya Sopka (Shishka);
-plateau - a highland plain, vast in area, with flat summit surfaces, well-defined slopes, for example, the Siberian plateau;
-plateau - an elevated plain, bounded by well-defined, often steep slopes;
-ridge - a narrow elongated hill with slopes steeper than 20 degrees and flat tops, for example, the Chernyshov ridge (ridge) in the Polar Urals;
- ridge - an elongated hill of considerable length with gentle slopes
and flat top surfaces;
-hill - a separate dome-shaped or conical hill with gentle slopes and relative elevations of less than 200 m;
– kurgan – an artificial hill;
-hillock - an isolated dome-shaped hill with a pronounced
sole line, steepness of slopes less than 25 degrees and relatively flat top;
- alluvial cone - a low hill, located at the mouth of the channel of drains and having the form of a truncated cone with slightly convex gentle slopes.
The negative forms (concave) of the relief include:
– oceans and seas ( ocean trenches ) - large areas of the earth's surface located below the level of the World Ocean, which are based on the oceanic, and along the periphery of the oceans and seas, the continental types of the earth's crust;
-basin - a decrease in considerable depth with steep slopes;
- depression - shallow depression with gentle slopes;
-valley - an elongated depression with a slope in one direction, with
slopes of various steepness and shape (terraces - Fig. 41–43);
- beam - an elongated recess of considerable length, having three sides
gentle soddy (or covered with vegetation) slopes that arose on the site of an aged ravine;
-ravine - an elongated depression (the depth and length of the ravines are different) with relatively steep and sometimes sheer bare slopes;
- a gully - a small elongated shallow depression with steep, non-soddy slopes on three sides;
- a hollow or a hollow of a drain - an elongated depression with gentle slopes covered with vegetation, and a depth of not more than 1 ... 2 meters.
Depending on the depth and area of \u200b\u200bdistribution (i.e., the size of the territory they occupy), landforms are divided into the smallest, very small, small, medium, large, largest and greatest.
The smallest forms of relief : furrows, ripples, etc., are characterized by appropriate dimensions - a few cm in height or depth, are not plotted on maps and do not have a significant impact on construction.
Very small relief forms have a height of several decimeters to 2 m (hummocks, potholes, small gullies), are plotted on large-scale maps and taken into account when planning the territory.
Small forms of relief ( microrelief )
occupy areas up to hundreds of m2 and have a height of several meters, are plotted on a map with scales of 1:10,000, 1:5000 and larger. The microrelief should be taken into account when assessing the engineering and geological conditions of the construction site.
Medium forms relief ( mesorelief ) can be traced over thousands of kilometers at a dissection depth of up to 200 m. Such reliefs are depicted on maps at a scale of 1:50,000 and make it possible to assess the engineering and geological conditions of settlements and microdistricts. Positive macroreliefs include hills, mounds, ridges, ridges of low elevations, ledges of terraces on rivers, lakes and seas; to negative macroreliefs - shallow ravines, beams, hollows, sinkholes, etc.
Small and medium landforms often have "local names", for example, ledges of erosional terraces in the Southern Urals are called prites on the river. Ai (Fig. 44) and comb river. Yuryuzan and others.
Large landforms ( macrorelief )
occupy areas of hundreds and thousands of km2, are distinguished by the dissection of the relief at a depth of 200 ... 2000 m, are displayed on maps with a scale of 1:100,000 and 1:1,000,000. Zyuratkul and Taganay (Fig. 45) ridges. Negative macroreliefs include large valleys, depressions of large reservoirs, in particular lakes Turgoyak and Zyuratkul. Macro-reliefs are taken into account when placing large construction areas.
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The largest landforms ( megarelief ) occupy gigantic areas of hundreds of thousands of km2 with a difference in elevations between positive and negative forms of 500 ... 4000 m, are depicted on maps with a scale of 1: 10,000,000. These include mountains, for example, the Ural Mountains, the Volga Upland, the Caspian lowland (basin) and their parts.
The Greatest ( planetary ) relief forms are measured in millions of km2, the difference in elevations reaches 2500 ... 6500 m. Positive macroreliefs include continents, negative ones - oceanic depressions, which have a different structure of the earth's crust under them.
Over time, it changes under the influence of various forces. Places where there were once great mountains are becoming plains, and in some areas there are volcanoes. Scientists are trying to explain why this is happening. And much of modern science is already known.
Reasons for transformations
The relief of the Earth is one of the most interesting mysteries of nature and even history. Because of how the surface of our planet has changed, the life of mankind has also changed. Change occurs under the influence of internal and external forces.
Among all landforms, large and small ones stand out. The largest of them are the continents. It is believed that hundreds of centuries ago, when there was no man yet, our planet had a completely different look. Perhaps there was only one mainland, which eventually broke up into several parts. Then they split up again. And all the continents that exist now appeared.
Another major form was the oceanic depressions. It is believed that earlier there were also fewer oceans, but then there were more of them. Some scientists argue that after hundreds of years new ones will appear. Others say that the water will flood some parts of the land.
The relief of the planet has changed over the centuries. Even despite the fact that a person sometimes greatly harms nature, his activity is not capable of significantly changing the relief. This requires such powerful forces that only nature has. However, a person cannot not only radically transform the relief of the planet, but also stop the changes that nature itself produces. Despite the fact that science has made a big step forward, it is not yet possible to protect all people from earthquakes, volcanic eruptions and much more.
Basic information
The relief of the Earth and the main landforms attract the close attention of many scientists. Among the main varieties are mountains, highlands, shelves and plains.
The shelf is those parts of the earth's surface that are hidden under the water column. Very often they stretch along the coast. The shelf is that type of relief that is found only under water.
Uplands are isolated valleys and even range systems. Much of what is called mountains is actually highlands. For example, Pamir is not a mountain, as many people think. The Tien Shan is also a highland.
Mountains are the most grandiose landforms on the planet. They rise above the land by more than 600 meters. Their peaks are hidden behind the clouds. It happens that in warm countries you can see mountains, the peaks of which are covered with snow. The slopes are usually very steep, but some daredevils dare to climb them. Mountains can form chains.
The plains are stability. The inhabitants of the plains are the least likely to experience changes in relief. They almost do not know what earthquakes are, because such places are considered the most favorable for life. A real plain is the most flat earthly surface.
Internal and external forces
The influence of internal and external forces on the Earth's relief is grandiose. If you study how the surface of the planet has changed over several centuries, you can see how what seemed eternal disappears. It is being replaced by something new. External forces are not able to change the Earth's relief as much as internal ones. Both the first and the second are divided into several types.
internal forces
The internal forces that change the Earth's relief cannot be stopped. But in the modern world, scientists from different countries are trying to predict when and where there will be an earthquake, where a volcanic eruption will occur.
Internal forces include earthquakes, movements, and volcanism.
As a result, all these processes lead to the emergence of new mountains and mountain ranges on land and at the bottom of the ocean. In addition, there are geysers, hot springs, chains of volcanoes, ledges, cracks, depressions, landslides, volcano cones and much more.
Outside forces
External forces are not capable of producing noticeable transformations. However, they should not be overlooked. The shaping of the Earth's relief includes the following: the work of wind and flowing waters, weathering, the melting of glaciers and, of course, the work of people. Although man, as mentioned above, is not yet able to greatly change the face of the planet.
The work of external forces leads to the creation of hills and ravines, hollows, dunes and dunes, river valleys, rubble, sand and much more. Water can destroy even a great mountain very slowly. And those stones that are now easily found on the shore may turn out to be part of a mountain that was once great.
Planet Earth is a grandiose creation in which everything is thought out to the smallest detail. It has changed over the centuries. There have been cardinal transformations of the relief, and all this - under the influence of internal and external forces. In order to better understand the processes taking place on the planet, it is imperative to know about the life that it leads, not paying attention to man.
The main landforms of the Earth
Continents and oceans are the main landforms of the Earth. Their formation is due to tectonic, cosmic and planetary processes.
Mainland- this is the largest massif of the earth's crust, which has a three-layer structure. Most of its surface protrudes above the level of the oceans. In the modern geological era, there are 6 continents: Eurasia, Africa, North America, South America, Australia, Antarctica.
World Ocean- a continuous water shell of the Earth, surrounding the continents and having a common salt composition. The world ocean is divided by continents into 4 oceans: the Pacific, the Atlantic, the Indian Islands and the Arctic.
The surface of the Earth is 510 million km 2. The share of land accounts for only 29% of the Earth's area. Everything else is the World Ocean, that is, 71%.
Mountains and plains, as well as continents and oceans, are the main landforms of the Earth. Mountains are formed as a result of tectonic uplifts, and plains as a result of the destruction of mountains.
Plains- large areas with a relatively flat surface. They vary in height. An example lowlands(from 0 to 200 m above sea level) can serve as the Amazonian lowland - the largest on Earth, as well as the Indo-Gangetic lowland. It happens that the lowlands are located below sea level - this is hollows. The Caspian lowland is located 28 m below sea level. An example of a plain proper is the largest East European Plain.
At altitudes of 200–500 m above sea level, hills. For example, Central Russian, Volga, and above 500 m - plateaus and highlands. The largest of them are the Central Siberian,
Brazilian, Deccan, Guiana, East African, Great Basin, Arabian.
The mountains- areas of the earth's surface, significantly elevated above sea level to a height of more than 500 m and strongly dissected. Mountains are considered low if their height is from 500 to 1000 m; medium - from 1000 to 2000 m and high - over 2000 m. The highest mountain peak on Earth - Mount Chomolungma (Everest) in the Himalayas has a height of 8848 m. You can determine the height of the mountains on a physical map using the height scale.
The sizes of landforms reflect the features of their origin. So, the largest landforms - tectonic- formed as a result of the prevailing influence of the internal forces of the Earth. Forms of medium and small scales were formed with the predominant participation of external forces (erosive forms).
Mountains differ not only in height, but also in shape (Table 7.3). A group of mountains stretched out in a chain is called mountain range. For example, the mountains of the Caucasus have such a shape.
