Height of various landforms. Types and forms of terrain

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 diverse.
The most characteristic landforms are:

Mountain - a rise on the earth's surface in the form of a dome or cone. A mountain has a peak, a base, and slopes.
The slopes can be flat or steep. If the slope immediately changes from smooth to steep, it is called a cliff. A very steep cliff is called a cliff.

Basin - a depression on the earth's surface, closed on all sides. You can figuratively imagine a basin as an element of the relief of the earth's surface, opposite the mountain.
In the basin there are slopes (or sides), as well as a bottom.

Hollow - a groove-shaped depression. In the hollow, there are also slopes and a bottom. A line drawn along the deepest part of the hollow is called drainage line .
The narrow ravine is called ravine (in the mountains - gorge ).

Ridge - the form of relief opposite 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 - low relief of the area between two neighboring ridges. Typically, a saddle is the beginning of two valleys extending in opposite directions from it.
In mountainous areas, saddles usually pass through 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 lowland . A plain located at an altitude of more than 200 m above sea level is called plateau .

To solve many problems in engineering construction, military affairs and others, it is necessary to have a reliable understanding of the topography of a given area. Projecting points on the earth's surface onto a horizontal plane makes it possible to study the distance between objects on this surface with varying degrees 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 mark on them the irregularities of the displayed area of ​​the terrain, i.e., the relief. To solve this problem, various leveling methods are used, the results of which are then plotted on a 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 widespread are three methods of drawing relief on a map - strokes, shading and horizontal lines. The method of drawing relief on a plane using strokes has not stood the test of time, and is not currently used, therefore, to depict the relief on topographic maps and plans, methods of horizontal lines and shading are usually used.
You can learn more about how terrain elements are depicted on maps in the next article.

Terrain is a collection of irregularities on the earth's surface. The terrain is divided into convex and concave irregularities of various shapes and sizes. But despite this, these irregularities can be divided into five types of relief surfaces: mountains, ridges, hollows, basins and saddles.

Mountain is a hill shaped like a cone. The mountain has a peak, from which the relief decreases towards the base.

Ridge It is a hill elongated in one direction. The ridge has a watershed line - a line connecting the opposite slopes of the ridge.

Basin is a closed depression. The basin has a relief shape opposite to the mountain. The basin has the lowest point - the bottom. Lakes and swamps often appear at the bottom.

Hollow is a relief form opposite the ridge - a depression elongated in one direction. As a rule, the hollows are covered with turf and bushes.

Saddle represents a decline between two peaks. In the mountains, trails, also called passes, run through ridges along saddles.

1 - mountain, 2 - basin, 3 - ridge, 4 - hollow, 5 - saddle, 6 - ledge

Relief depiction on topographic maps is carried out in three ways: the contour method, the hillshade and the hypsometric method. The hypsometric and hillshade method is the designation of heights using shades of colors depending on the height and is used on maps with a scale starting from 1:500000. The most common method is a method of drawing horizontal lines that indicate relief unevenness that have the same height. The direction of the slope of the horizontal lines is indicated by a dotted line with an arrow at the end, i.e. for example, if a mountain is indicated, then the arrow will be directed in the opposite direction from the top towards the bottom.

In addition to the arrow indicating the direction of the slope, it can be determined by other signs. Based on the elevation marks, it is obvious that the slope will be directed from a higher point to a lower one. According to the contour marks - the top of the numbers of the contour marks is directed towards the heights of ridges and mountains, i.e. in the opposite direction from the direction of the slope. Along lakes, rivers and streams - water flows to the lowest places, therefore the direction of the slope will be directed towards water bodies.

The distance between two horizontal lines on the ground is called relief section height. Rasta Every fifth horizontal line is made bolder to make it easier to read the terrain. The closer the horizontal lines are to each other, the steeper the slope. On topographic maps with a scale of 1:25000, horizontal lines are drawn every 5 meters, 1:50000 - every 10 m, 1:100000 - every 20 m. The zero horizontal line is the average level of the Baltic Sea.

Determining the steepness of the slope.
The distance between two contour lines on a map is called mortgage, which shows the steepness of the slope. The easiest way to determine steepness is to use a ruler or by eye. To do this, you need to know that on maps of Russia the standard section height for any scale is such that a slope of 1 cm is equal to a slope slope of 1°. Therefore, the number of times the elevation on the map is less than 1 cm, the number of times the slope is greater than 1°, and vice versa.

For example, the location on the map is 2 mm, that is, five times less than 1 cm, therefore the steepness is five times greater than 1°, namely 5°.

Despite the wide variety of unevenness of the earth's surface, the main forms of relief can be distinguished: mountain, basin, ridge, hollow, saddle.

The top of the mountain, the bottom of the basin, and the saddle point are characteristic points of the relief; the watershed line of a ridge, the drainage line of a ravine, the line of the base of a mountain or ridge, the edge line of a basin or ravine are characteristic lines of the relief.

Classification

Landforms vary:

Planetary landforms

• Geosynclinal belts
• Mid-ocean ridges

Mega landforms

Macro relief forms

Individual ridges and depressions of a mountainous country Examples: Main Caucasus Range, Bzyb Range (Abkhazia)...

Mesoforms of relief

Microforms of relief

Nanoforms of relief

Examples: meadow tussock, surchin, small erosion grooves, ripple marks on the surface of aeolian forms or on the seabed.

Methods of depicting relief

The method of depicting the relief should provide a good spatial understanding of the terrain, reliable determination of the directions and steepness of slopes and marks of individual points, and the solution of various engineering problems.

Since the existence of geodesy, several methods have been developed for depicting relief on topographic maps. Let's list some of them:

1. A promising way.
2. Washing method. This method is used on small-scale maps. The Earth's surface is shown in brown: the larger the marks, the thicker the color. The depths of the sea are shown in blue or green: the greater the depth, the deeper the color.
3. Hatching method.
4. Marking method. With this method, marks of individual terrain points are marked on the map.
5. Contour method.

Currently, on topographic maps, the method of contours is used in combination with the method of marks, and on one square decimeter of the map, as a rule, at least five point marks are labeled.

Notes

Wikimedia Foundation. 2010.

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Lesson questions:

1. Types and forms of terrain. The essence of depicting relief on maps using contour lines. Types of contours. Depiction of typical relief forms by horizontal lines.

1.1 Types and forms of terrain.
In military affairs terrain understand the area of ​​the earth's surface on which combat operations are to be conducted. Irregularities in the earth's surface are called terrain, and all objects located on it created by nature or human labor (rivers, settlements, roads, etc.) - local items.
Relief and local objects are the main topographical elements of the terrain that influence the organization and conduct of combat, the use of military equipment in combat, conditions of 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 precise location relative to each other. It makes it possible to explore any territory in a relatively short time. A preliminary study of the terrain and decision-making for a unit (unit, formation) to carry out a particular combat mission is usually carried out on a map, and then clarified on the ground.
The terrain, influencing combat operations, in one case can contribute to the success of troops, and in another have a negative impact. Combat practice convincingly shows that the same terrain can give greater 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 relatively low (up to 2°) slope 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 the degree of ruggedness. Its clayey, loamy, sandy loam, and peat soils allow the unimpeded movement of military equipment in dry weather and significantly complicate movement during the rainy season, spring and autumn thaw. It can be cut up by river beds, ravines and ravines, and have many lakes and swamps, which significantly limit the ability of troops to maneuver and reduce the pace of the offensive (Fig. 2).
Flat terrain is usually more favorable for organizing and conducting an offensive and less favorable for defense.

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

Hilly terrain ensures the movement and deployment of troops hidden from enemy ground observation, facilitates the selection of places 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 for both offense and defense.
Mountain landscape represents areas of the earth's surface that are significantly elevated above the surrounding area (with absolute heights of 500 m or more) (Fig. 5). It is distinguished by complex and varied terrain and specific natural conditions. The main forms of relief are mountains and mountain ranges with steep slopes, often turning into cliffs and rocky cliffs, as well as hollows and gorges located between mountain ranges. Mountainous terrain is characterized by sharply rugged terrain, the presence of inaccessible areas, a sparse network of roads, a limited number of settlements, rapid river flows with sharp fluctuations in water levels, a variety of climatic conditions, and the predominance of rocky soils.
Combat operations in mountainous areas are considered as actions under special conditions. Troops often have to use mountain passes, making observation and firing, orientation and target designation difficult, at the same time it contributes to the secrecy of the location and movement of troops, facilitates the installation of ambushes and engineering barriers, and the organization of camouflage.

1.2 The essence of depicting relief on maps using contour lines.
Relief is the most important element of the terrain, determining its tactical properties.
The image of the relief on topographic maps gives a complete and fairly detailed idea of ​​the unevenness of the earth's surface, the shape and relative position, elevations and absolute heights of terrain points, the prevailing steepness and length of the slopes.

1.3 Types of contour lines.
Horizontal- a closed curved line on a map, which corresponds to a contour on the ground, all points of which are located at the same height above sea level.
The following horizontal lines are distinguished:

• basic(solid) - the relief section corresponding to the height;
• thickened - every fifth main horizontal line; stands out for ease of reading the relief;
• additional horizontal lines(semi-horizontals) - drawn by a broken line at a height of the relief section equal to half the main one;
• auxiliary - are depicted by short broken thin lines at an arbitrary height.

Distance between two adjacent main horizontal heights are called the height of the relief section. The height of the relief section is indicated on each sheet of the map under its scale. For example: “Continuous horizontal lines are drawn every 10 meters.”
To facilitate the calculation of contours when determining the heights of points on the map, all solid contours corresponding to the fifth multiple of the section height are drawn thickly and a number is placed on it indicating the height above sea level.
In order to quickly determine the nature of surface irregularities on maps when reading a map, special slope direction indicators are used - berg strokes- in the form of short lines placed on horizontal lines (perpendicular to them) in the direction of slopes. They are placed on the bends of horizontal 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 characteristic shapes 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 gaps between the main contour lines are very large (more than 3 - 4 cm on the map).
Auxiliary contours used to depict individual relief details (saucers in steppe regions, depressions, individual hillocks on flat terrain), which are not conveyed by the main or additional horizontal lines.

1.4 Representation of typical relief forms by horizontal lines.
Relief on topographic maps is depicted by curved closed lines connecting terrain points that have the same height above the level surface, taken as the beginning of the height reference. Such lines are called horizontals. The image of the relief with horizontal lines is supplemented by captions of absolute heights, characteristic points of the terrain, some horizontal lines, as well as numerical characteristics of relief details - height, depth or width (Fig. 7).

Some typical landforms on maps are displayed not only as main ones, but also as additional and auxiliary contour lines (Fig. 8).

Rice. 8. Image of typical relief forms

2. Determination on the map of absolute heights and relative elevations of terrain points, ascents and descents, and steepness of slopes.

2.1. Determination of absolute heights and relative elevations of terrain points on the map

2.2. Identification on the map of ascents and descents along the route.

2.3.Determining the steepness of the slopes on the map.
The steepness of the slope on the map is determined by its position - the distance between two adjacent main or thickened horizontal lines; the lower the laying, the steeper the slope\.
To determine the steepness of the slope, you need to measure the distance between the horizontal lines with a compass, find the corresponding segment on the location graph and read the number of degrees (Fig. 11).
On steep slopes, this distance is measured between thickened horizontal lines 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 horizontal lines.

Notes

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terrain- Shape (outline) of the outer surface of the lithosphere; a set of irregularities on land, the bottom of oceans and seas, varied in outline, size, origin, age and history of development. [RD 01.120.00 KTN 228 06] Mainline topics... ...

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- (French relief, from Latin relevare to raise, elevate). Convex image; sculptural works, more or less convex. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. RELIEF 1) convex sculptural images... ... Dictionary of foreign words of the Russian language

RELIEF, relief, husband. (French relief). 1. Convex image on a plane (special). Reliefs can be weakly convex bas-reliefs and strongly convex high reliefs. 2. The structure of the earth's surface (geographical, geological). Rough terrain. Mountain... ... Ushakov's Explanatory Dictionary

1. Sculptural image on a plane. It can be recessed (coylanogryph) or protruding (bas-relief, high relief). 2. Configuration of the surface of the land plot (terrain). Source: Dictionary of architectural and construction terms... ... Construction dictionary

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