Conventional signs in geography. What is a map legend? The meaning of the term, conventional signs

Scale, or contour, conditional topographic signs are used to depict local objects that, by their size, can be expressed on a map scale, that is, their dimensions (length, width, area) can be measured on a map. For example: a lake, a meadow, large gardens, quarters of settlements. The contours (outer boundaries) of such local objects are depicted on the map with solid lines or dotted lines, forming figures similar to these local objects, but only in a reduced form, that is, on a map scale. Solid lines show the contours of quarters, lakes, wide rivers, and the contours of forests, meadows, swamps - dotted lines.

Figure 31.

Structures and buildings, expressed on the scale of the map, are depicted by figures similar to their actual outlines on the ground and are painted over in black. Figure 31 shows several scale (a) and off-scale (b) symbols.

Off-scale symbols

Explanatory topographic signs serve to additionally characterize local objects and are used in combination with large-scale and off-scale signs. For example, a figurine of a conifer or deciduous tree inside the contour of the forest shows the dominant tree species in it, the arrow on the river indicates the direction of its flow, etc.

In addition to signs, full and abbreviated signatures are used on the maps, as well as digital characteristics of some objects. For example, the signature "mash." with the sign of the plant means that this plant is a machine-building plant. The names of settlements, rivers, mountains, etc. are fully signed.

Numerical designations are used to indicate the number of houses in rural settlements, the height of the area above sea level, the width of the road, the characteristics of the carrying capacity and the size of the bridge, as well as the size of the trees in the forest, etc. Numerical designations related to conventional relief signs are printed in brown , width and depth of rivers in blue, everything else in black.

Let us briefly consider the main types of topographic symbols for depicting the area on the map.

Let's start with terrain. Due to the fact that the observation conditions, terrain passability and its protective properties largely depend on its nature, the terrain and its elements are depicted on all topographic maps very detailed. Otherwise, we could not use the map to study and evaluate the area.

In order to clearly and fully imagine the area on the map, you must first of all be able to quickly and correctly determine on the map:

Types of irregularities earth's surface and their relative position;

Mutual excess and absolute heights of any points of the terrain;

The shape, steepness and length of the slopes.

On modern topographic maps, the relief is depicted by contour lines, that is, curved closed lines, the points of which are located on the ground at the same height above sea level. In order to better understand the essence of the depiction of the relief by contour lines, let us imagine an island in the form of a mountain, gradually flooded with water. Let us assume that the water level successively stops at regular intervals equal in height to h meters (Fig. 32).

Then each water level will have its own coastline in the form of a closed curved line, all points of which have the same height. These lines can also be considered as traces of a section of terrain irregularities by planes parallel to the level surface of the sea, from which heights are counted. Based on this, the distance h in height between the secant surfaces is called the height of the section.

Figure 32.

So if all lines equal heights project on the level surface of the sea and depict them on a scale, then we will get an image of the mountain on the map in the form of a system of curved closed lines. These will be horizontal.

In order to find out whether it is a mountain or a basin, there are slope indicators - small dashes that are applied perpendicular to the horizontal lines in the direction of lowering the slope.

Figure 33.

The main (typical) landforms are shown in Figure 32.

The height of the section depends on the scale of the map and on the nature of the relief. normal height section is considered to be a height equal to 0.02 of the map scale value, that is, 5 m for a map of a scale of 1:25 OOO and, respectively, 10, 20 m for maps of scales 1: 50,000, 1: 100,000. Contours on the map corresponding to the height set for it sections are drawn by solid lines and are called main or solid contour lines. But it happens that at a given height of the section, important details of the relief are not expressed on the map, since they are located between the cutting planes.

Then half semi-horizontals are used, which are drawn through half the main height of the section and are plotted on the map with broken lines. To determine the count of contour lines when determining the height of points on the map, all solid contour lines corresponding to five times the height of the section are drawn thickened (thickened contour lines). So, for a map with a scale of 1: 25,000, each horizontal line corresponding to the height of the section 25, 50, 75, 100, etc. will be drawn as a thickened line on the map. The main height of the section is always indicated under the south side of the map frame.

The heights of the hills on the ground depicted on our maps are counted from the level Baltic Sea. The heights of points on the earth's surface above sea level are called absolute, and the excess of one point above another is called relative excess. Horizontal marks - digital inscriptions on them - indicate the height of these terrain points above sea level. The top of these numbers is always facing upward slope.

Figure 34.

Marks of command heights, from which the terrain is better viewed from the most important objects on the map than from others (large settlements, road junctions, passes, mountain passes, etc.), are applied in large numbers.

With the help of contour lines, you can determine the steepness of the slopes. If you look closely at Figure 33, you can see from it that the distance between two adjacent contours on the map, called the laying (with a constant section height), changes depending on the steepness of the slope. The steeper the slope, the smaller the laying and, conversely, the more flat the slope, the greater the laying. Hence the conclusion follows: steep slopes on the map will differ in the density (frequency) of contour lines, and in flat places the contour lines will be less frequent.

Usually, to determine the steepness of the slopes, a drawing is placed on the margins of the map - laying scale(Fig. 35). Along the lower base of this scale are numbers that indicate the steepness of the slopes in degrees. On the perpendiculars to the base, the corresponding values ​​of the deposits are plotted on the scale of the map. On the left side, the scale of embeddings is built for the main height of the section, on the right - at five times the height of the section. To determine the steepness of the slope, for example, between points a-b(Fig. 35), you need to take this distance with a compass and set aside on the scale and read the steepness of the slope - 3.5 °. If it is required to determine the steepness of the slope between the horizontals thickened n-t, then this distance should be set aside on the right scale and the steepness of the slope in this case will be equal to 10 °.

Figure 35.

Knowing the property of contour lines, it is possible to determine from the map and the shape various kinds stingrays (Fig. 34). In an even slope, the inceptions will be approximately the same throughout its entire length, in a concave one they increase from the top to the sole, and in a convex one, on the contrary, the inceptions decrease towards the sole. In wavy slopes, the laying changes according to the alternation of the first three forms.

When depicting relief on maps, not all of its elements can be expressed as contour lines. So, for example, slopes with a steepness of more than 40 ° cannot be expressed as horizontals, since the distance between them will be so small that they will all merge. Therefore, slopes with a steepness of more than 40 ° and steep are indicated by horizontal lines with dashes (Fig. 36). Moreover, natural cliffs, ravines, gullies are indicated in brown, and artificial embankments, excavations, mounds and pits are indicated in black.

Figure 36.

Consider the main conditional topographic signs for local objects. Settlements are depicted on the map with the preservation of external borders and planning (Fig. 37). All streets, squares, gardens, rivers and canals, industrial enterprises, outstanding buildings and structures that have the value of landmarks are shown. For better visibility, fire-resistant buildings (stone, concrete, brick) are painted over in orange, and blocks with non-fire-resistant buildings are painted in yellow. The names of settlements on the maps are signed strictly from west to east. The type of administrative value of a settlement is determined by the type and size of the font (Fig. 37). Under the signature of the name of the settlements, you can find a number indicating the number of houses in it, and if there is a district or village council in the settlement, the letters “RS” and “SS” are additionally put.

Figure 37-1.

Figure 37-2.

No matter how poor the area is in local objects or, on the contrary, saturated, there are always separate objects on it, which stand out from the rest in size and are easily recognized on the ground. Many of them can be used as landmarks. This should include: factory chimneys and prominent buildings, tower-type buildings, wind turbines, monuments, auto columns, signs, kilometer posts, separately standing trees etc. (Fig. 37). Most of them, but due to their size, cannot be shown on the scale of the map, so they are depicted on it with off-scale signs.

The road network and crossings (Fig. 38, 1) are also depicted by off-scale conventional signs. Data on the width of the carriageway, road surface, indicated on the conventional signs, make it possible to evaluate their throughput, carrying capacity, etc. Railways, depending on the number of tracks, are indicated by dashes across the conventional road sign: three dashes - a three-track railway, two dashes - a double-track railway . Stations, embankments, cuts, bridges and other structures are shown on railways. At bridges longer than 10 m, its characteristic is signed.

Figure 38-1.

Figure 38-2.

Figure 39.

For example, the signature at the bridge ~ means that the length of the bridge is 25 m, the width is 6 m, and the load capacity is 5 tons.

Hydrography and structures associated with it (Fig. 38, 2), depending on the scale, are shown with greater or lesser detail. The width and depth of the river is signed as a fraction 120/4.8, which means:

The width of the river is 120 m and its depth is 4.8 m. The speed of the river flow is shown in the middle of the symbol with an arrow and a number (the number indicates the speed of 0.1 meters per second, and the arrow indicates the direction of the flow). On rivers and lakes, the height of the water level in the low water period (mark of the water's edge) in relation to sea level is also signed. At the fords, it is signed: in the numerator - the depth of the ford in meters, and in the denominator - the quality of the soil (T - hard, P - sandy, B - viscous, K - rocky). For example, br. 1.2/k means that the ford is 1.2 m deep and the bottom is rocky.

The soil and vegetation cover (Fig. 39) is usually depicted on maps with large-scale symbols. These include forests, shrubs, gardens, parks, meadows, marshes, salt marshes, as well as sands, rocky surfaces, and pebbles. In the forests, its characteristics are indicated. For example, at mixed forest(spruce with birch) are the numbers 20/\0.25 - this means that the average height of trees in the forest is 20 m, their average thickness is 0.25 m, the average distance between tree trunks is 5 meters.

Figure 40.

Swamps are depicted depending on their passability on the map: passable, difficult to pass, impassable (Fig. 40). Passable swamps have a depth (to solid ground) of no more than 0.3-0.4 m, which is not shown on the maps. The depth of difficult and impenetrable swamps is signed next to the vertical arrow indicating the location of the sounding. On the maps, the cover of swamps (grass, moss, reed), as well as the presence of forests and shrubs on them, are shown with the corresponding conventional signs.

Hilly sands differ from flat sands and are indicated on the map by a special symbol. In the southern steppe and semi-steppe regions, there are areas of terrain with soil abundantly saturated with salt, which are called solonchaks. They are wet and dry, some are impassable, while others are passable. On the maps they are indicated by conventional signs - "hatching" of blue color. The image of solonchaks, sands, swamps, soil and vegetation cover is shown in Figure 40.

Off-Scale Conventional Signs of Local Items

Answer: Off-scale symbols are used to depict small local objects that are not expressed on the scale of the map - detached trees, houses, wells, monuments, etc. If they were depicted on the scale of the map, they would turn out to be in the form of a point. Examples of depicting local objects with off-scale conventional signs are shown in Figure 31. The exact location of these objects depicted with off-scale conventional signs (b) is determined by the center of the symmetrical figure (7, 8, 9, 14, 15), in the middle of the base of the figure (10, 11) , at the top of the corner of the figure (12, 13). Such a point on the figure of an off-scale symbol is called the main point. In this figure, the arrow shows the main points of the conventional signs on the map.

This information is useful to remember in order to correctly measure the distance between local objects on the map.

(This issue is discussed in detail in question No. 23)

Explanatory and conventional signs of local objects

Answer: Types of topographic symbols

The area on maps and plans is depicted by topographic symbols. All conventional signs of local objects according to their properties and purpose can be divided into the following three groups: contour, scale, explanatory.

Comparison of the properties of a geographical map and a plan of the area.

Area plan. Geographic map

Map- a reduced generalized symbolic image of the surface of the Earth (its part), other planets or the celestial sphere, built on a scale and projection.

Terrain plan- a drawing of the area, made in conventional symbols and on a large scale (1: 5000 and larger).

When constructing plans, the curvature of the earth's surface is not taken into account, because small areas or areas of terrain are depicted.

The difference between the site plan and geographical map:

1) the plans depict small areas of the terrain, so they are built on a large scale (for example, 1 cm - 5 m). Geographic maps show much larger territories, their scale is smaller;

2) the plan depicts the area in detail, keeping the exact outlines of the depicted objects, but only in a reduced form. The large scale of the plan allows you to reflect on it almost all objects located on the ground. On a map that has a smaller scale, all objects cannot be plotted, therefore, when creating maps, objects are generalized. The exact outlines of all objects on the map also cannot be shown, so they are distorted to one degree or another. Many objects on the map, in contrast to the plan, are depicted with off-scale conventional signs;

3) when constructing a plan, the curvature of the earth's surface is not taken into account, since a small area of ​​\u200b\u200bthe terrain is depicted. When building a map, it is always taken into account. Maps are built in certain cartographic projections;

4) there is no degree network on the plans. Parallels and meridians must be put on the map;

5) on the plan, the direction to the north is by default considered the direction up, the direction to the south - down, to the west - to the left, to the east - to the right (sometimes on the plan the direction north - south is shown by an arrow that does not coincide with the direction up - down). On the maps, the north-south direction is determined by the meridians, the west-east by the parallels.

Comparison of cartographic image methods. Ways of depicting objects and phenomena on geographical maps

Conventional signs - designations used on maps to depict various objects and their qualitative and quantitative characteristics. With the help of conventional signs, they denote both real objects (for example, settlements) and abstract ones (for example, population density). Conventional signs are intended to indicate the type and some characteristics of the objects (phenomena) depicted on the map and determine their position in space.

Symbols are:

— off-scale(used to depict objects that cannot be expressed on a map scale). Are these drawings or geometric figures, the shape of which usually resembles the depicted object (Fig. 1). Alphabetic symbols also refer to off-scale conventions. The position of the object on the ground corresponds to the center of the sign of a symmetrical shape, the middle of the base of the sign with a wide base, the top of the corner of the sign with the base in the form right angle, the center of the lower figure of the sign, which is a combination of several figures;

— linear(used to depict objects of a linear nature - rivers, roads, borders, pipelines, etc.). On a scale, they convey only the length and shape of the object, their width is exaggerated, so it cannot be measured (Fig. 2);

— areal, or contour(used to depict geographical objects that occupy a certain area - a lake, an array of forests, etc.). The actual value of the objects is transmitted (Fig. 3).

They consist of a contour (forest, swamp, etc.) and its filling (color, shading).

Explanatory symbols (for example, arrows showing the direction of the flow of the river, figures of deciduous and coniferous trees etc.), signatures, alphabetic and numeric designations also carry certain information on the map.

Cartographic imaging methods

Quality background method. It is used to display on the map the qualitative features of certain objects or phenomena that have a continuous distribution on the earth's surface or occupy large areas. Its essence lies in the fact that on the map allocate homogeneous areas according to a certain feature (features) (for example, natural areas) and paint over (or hatch) them in the colors selected for them (hatching).

Area method. area- the area of ​​\u200b\u200bdistribution on the earth's surface of a phenomenon (for example, the territory on which a certain animal lives, or the territory on which this or that agricultural crop is grown, etc.).

The isoline method. Contours(from the Greek isos - equal) - lines on maps passing through points with the same value of any quantitative indicator (temperature, precipitation, depth, height, etc.) characterizing the depicted phenomenon. For example, isotherms are lines connecting places with the same temperature; isobaths - lines connecting places with the same depth; Contours are lines connecting points on the earth's surface with the same absolute height. The essence of the isoline method is that on the map points with the same values ​​of a certain indicator are connected by thin lines, i.e., contour lines are drawn.

Movement lines. Lines (arrows) show the direction of movement of any objects - air masses, winds, ocean currents, rivers, etc.

Determination of directions, measurement of distances on the plan and map

On the plan, north-south is indicated by an arrow. If there is no arrow on the plan, then it is considered that north is above, south is below.

On the map, directions are determined using a degree network. The north-south direction corresponds to the direction of the meridians, the west-east direction corresponds to the parallels.

Azimuth measurements according to the cards are produced using a protractor. Azimuth- the angle formed at a given point or on the map between the direction to the north and any object and counted clockwise.

So, if the object is strictly north of the point where the observer is located, then the azimuth to it will be 0 °, to the east - 90 °, to the south - 180 °, to the west - 270 °. Azimuths can have values ​​from 0° to 360°. In order to measure the azimuth on the map, it is necessary to draw a line parallel to the north-south direction through the starting point of the direction being determined. Then, also through the point, draw a line connecting the point and the object to which you want to determine the azimuth. And then, using a protractor, measure the resulting angle (azimuth), given that the azimuth is always counted clockwise.

Determination of geographical coordinates

Gradient network and its elements. Degree network of the Earth- a system of meridians and parallels on geographical maps and globes, which serves to count the geographical coordinates of points on the earth's surface - longitudes and latitudes - or to map objects by their coordinates.

To create a degree network, certain reference points are needed. The spherical shape of the Earth determines the existence of two fixed points on the earth's surface - the poles. An imaginary axis passes through the poles, around which the Earth rotates.

Geographic poles- mathematically calculated points of intersection of the imaginary axis of rotation of the Earth with the earth's surface.

Equator- an imaginary line on the earth's surface, obtained by mentally dissecting the ellipsoid into two equal parts (Northern and Southern hemisphere). All points on the equator are equidistant from the poles. The plane of the equator is perpendicular to the Earth's axis of rotation and passes through its center. The hemispheres are mentally separated by many more planes parallel to the plane of the equator. The lines of their intersection with the surface of the ellipsoid are called parallels. All of them, like the plane of the equator, are perpendicular to the axis of rotation of the planet. Parallels on the map and the globe can be drawn as many as you like, but usually on training maps they are drawn at intervals of 10-20 °. Parallels are always oriented from west to east. The circumference of the parallels decreases from the equator to the poles. It is highest at the equator and zero at the poles.

When crossing the globe imaginary planes passing through the axis of the Earth perpendicular to the plane of the equator, large circles are formed - meridians. Meridians can also be drawn through any point of the ellipsoid. All of them intersect at the points of the poles (Fig. 4). The meridians are oriented from north to south. Average arc length of 1° meridian: 40,008.5 km: 360° = 111 km. All meridians are the same length. The direction of the local meridian at any point can be determined at noon by the shadow of any object. In the Northern Hemisphere, the end of the shadow always shows the direction to the north, in the Southern - to the south.

The degree network is necessary for counting the geographical coordinates of points on the earth's surface - latitude and longitude.

Geographic latitude- distance along the meridian in degrees from the equator to any point on the surface of the Earth. The equator is the starting point. The latitude of all points on it is 0. At the poles, the latitude is 90°. North latitude is measured north of the equator, south latitude is measured south.

Geographic longitude is the distance along the parallel in degrees from prime meridian to any point on the earth's surface. All meridians are equal in length, so for the reference it was necessary to choose one of them. They became the Greenwich meridian, passing near London (where the Greenwich Observatory is located). Longitude is measured from 0° to 180°. To the east of the zero meridian to 180 °, eastern longitude is counted, to the west - western.

Thus, using degree network, it is possible to determine exactly geographical coordinates- quantities that determine the position of a point on the earth's surface relative to the equator and the prime meridian. For example, the geographic coordinates of Cape Chelyuskin (the northernmost point of Eurasia) are 78° N. sh. and 104° E. d.

Determination of distances on the map

scale called the ratio of the length of the line in the drawing, plan or map to the length of the corresponding line in reality. The scale shows how many times the distance on the map is reduced relative to the actual distance on the ground. If, for example, the scale of a geographical map is 1:1,000,000, this means that 1 cm on the map corresponds to 1,000,000 cm on the ground, or 10 km.

There are numerical, linear and named scales.

Numerical scale is depicted as a fraction, in which the numerator is equal to one, and the denominator is a number showing how many times the lines on the map (plan) are reduced relative to the lines on the ground. For example, a scale of 1:100,000 shows that all linear dimensions on the map are reduced by 100,000 times. Obviously, the larger the scale denominator, the smaller the scale; with a smaller denominator, the scale is larger. The numerical scale is a fraction, so the numerator and denominator are given in the same measurements (centimeters).

Linear scale is a straight line divided into equal segments. These segments correspond to a certain distance on the depicted terrain; divisions are indicated by numbers. The measure of length along which the divisions on the scale bar are marked is called the base of the scale. In our country, the scale base is taken equal to 1 cm. The number of meters or kilometers corresponding to the scale base is called the scale value. When constructing a linear scale, the number 0, from which the counting of divisions begins, is usually placed not at the very end of the scale line, but retreating one division (base) to the right; on the first segment to the left of 0, the smallest divisions of the linear scale are applied - millimeters. The distance on the ground corresponding to one smallest division of the linear scale corresponds to the accuracy of the scale, and 0.1 mm corresponds to the maximum accuracy of the scale. The linear scale compared to the numerical one has the advantage that it makes it possible to determine the actual distance on the plan and map without additional calculations.

Named Scale- the scale expressed in words, for example, in 1 cm 250 km. (Fig. 5):

Measuring distances on the map and plan. Measuring distances with a scale. To measure the distance, you need to draw a straight line (if you need to know the distance in a straight line) between two points and use a ruler to measure this distance in centimeters, and then multiply the resulting number by the scale value. For example, on a map with a scale of 1: 100,000 (in 1 cm 1 km), the distance is 5 cm, i.e. on the ground, this distance is 1.5 = 5 (km). If you need to measure the distance between objects marked with off-scale conventional signs, then measure the distance between the centers of the conventional signs.

Measuring distances using a degree network. To calculate distances on a map or globe, the following quantities can be used: the length of an arc of 1° of the meridian and 1° of the equator is approximately 111 km. The total length of the earth's meridian is 40,009 km. Due to the fact that the Earth is flattened at the poles (polar compression), the length of an arc of 1 ° along the meridian at the equator (110.6 km) is less than at the poles (111.7 km). It is believed that the average length of 1 ° meridian is 111.1 km. The length of the arc 1° along the parallels decreases towards the poles. At the equator, it can also be taken equal to 111 km, and at the poles - 0 (because the pole is a point). To determine the distance in kilometers between two points lying on the same meridian, calculate the distance between them in degrees, and then multiply the number of degrees by 111.1 km. To determine the distance between two points on the equator, you also need to determine the distance between them in degrees, and then multiply by 111.1 km. To determine the distance between two points located on the same parallel, it is necessary to know the number of kilometers corresponding to the length of 1 ° arc of each particular parallel.

Definition of standard and zone time

Time Zones. Local and standard time. Solar time at points located on the same meridian is called local . Due to the fact that at each moment of the day it is different on all meridians, it is inconvenient to use it. Therefore, according to the international agreement, standard time was introduced. The entire surface of the Earth was divided along the meridians into 24 zones of 15 ° longitude. Belt (the same within each belt) time is the local time of the median meridian of this belt. Zero belt - this is a belt, the median meridian of which is the Greenwich (zero) meridian. From it, the belts are counted to the east.

Since 2014, 11 time zones have been established on the territory of Russia. The starting point for calculating the local time of time zones is Moscow time- time of the II time zone (see map). Thus, the difference in time between the first time zone and the eleventh is 10 hours.

It is conditionally believed that a new day begins in the 12th time zone (through which the 180 ° meridian passes - the date line). To the west of the international date line, a new day begins (according to the calendar). Therefore, in the logbook of a ship that sails from west to east, one day should be counted twice, and a ship moving from east to west, as it were, "skips" one day, after December 31 it immediately falls into January 2.

The use of statistical materials to determine trends in the development of geographical processes and phenomena

To reflect trends in the development of processes, statistical tables are often used, where data are presented as a percentage of the previous year - the volume of last year's production is 100%. Therefore, if any number greater than 100 is indicated for the next year in the table, then the volume of production in this year was greater than in the previous one.

Building a relief profile on a map

The image of the relief on the maps. The relief on the maps is depicted by contour lines, special symbols and elevation marks.

Contours- lines on the map along which all points of the earth's surface have the same absolute height. The difference between two heights of adjacent horizontals is called the relief section. The smaller the cross section of the relief, the more detailed it is depicted. The size of the relief section depends on the scale of the map and on the nature of the relief itself. The most detailed relief is depicted on topographic maps. For example, on a map at a scale of 1:25,000 (at 1 cm 250 m), solid contour lines are drawn through 5 m, and on a map at a scale of 1: 100,000 (at 1 cm 1 km), a relief section of 20 m is used for flat areas and 40 m for mountain. On small-scale maps, an uneven section of the relief is usually used: more frequent in flat areas and enlarged in mountainous areas. Yes, on physical map Russia on a scale of 1:25,000,000, horizontal lines are drawn at a height of 0, 200, 500, 1000, 2000, 3000, 4000 m. Isobaths (depth contours) are also shown.

Horizontally, one can easily determine the absolute height of any point on the earth's surface and the relative height of two points (the excess of one over the other). Contours also help determine the steepness of slopes. The closer the horizontals are to each other, the steeper the slope. Additional information about the relief on topographic maps is given berghashes- small strokes drawn perpendicular to the horizontals, indicating in which direction the relief is lowering.

For the depiction of relief forms that are not expressed by horizontal lines (for example, sharp ledges, cliffs, ravines, etc.), special conventional signs are used.

Absolute heights peaks or troughs on the maps are signed with numbers. Absolute heights are given in meters.

Understand general character relief changes are helped by elements of hydrography - for example, if a river is depicted on the map, then, as a rule, there is a general lowering of the relief of the right left bank to its channel. The direction of the river flow also indicates the direction in which the absolute height of the points decreases.

Topographic symbols

Conventional signs , which are used on topographic maps and plans, are mandatory for all organizations conducting topographic work.

Depending on the scale of the plan or map being created, the corresponding symbols are also used. In our country, the currently valid symbols are:

Symbols for a topographic map at a scale of 1:10000. Moscow: Nedra, 1977.

Symbols for topographic plans at scales 1:5000, 1:2000, 1:1000, 1:500. Moscow: Nedra, 1973.

Symbols, font samples and abbreviations for topographic maps at scales 1:25000, 1:50000, 1:100000. M.: Nedra, 1963.

Conventional signs for ease of use, they are grouped according to homogeneous features and placed in tables consisting of a serial number, the name of a conventional sign and its image. At the end of the tables there are explanations for the application and drawing conventional signs , as well as an alphabetical index of conventional signs with their serial numbers, a list of abbreviations of explanatory inscriptions, frame design samples and font samples indicating the name of the font, its size and index according to the "Album of Cartographic Fonts".

Students of geodetic specialties are required not only to know the symbols in order to freely read topographic maps and plans, but also ability to draw them in strict accordance with the requirements of instructions and instructions. To this end, in curriculum a course of topographic drawing is provided, which is understood as the process of graphic reproduction on paper with the help of conventional signs and explanatory inscriptions of the results of various types of surveys.

Conventional signs drawn by hand and with the help of drawing tools:

straight-line contours are drawn with a drawing pen,

curvilinear contours are drawn with a curved leg,

calipers draw conventional signs of forests, gardens and shrubs.

When drawing conventional signs, one should strictly adhere to those sizes and colors that are shown in the current conventional signs. The use of any other symbols is prohibited.

Classification of conventional signs

Conventional signs serve to designate various objects and their qualitative and quantitative characteristics. The completeness of the content of the map, its visibility and clarity depend on the selection of conventional signs. Conventional signs reveal the nature of the terrain and contribute to understanding the content of topographic maps and plans. Therefore, such conventional signs are developed that resemble the appearance of the depicted object. In addition, such requirements are imposed on conventional signs as ease of memorization, ease of drawing and cost-effectiveness of the image.

depending on the size of the depicted objects and plan or map scale conventional signs can be divided into several groups:

Scale symbols or areal are intended to depict local objects in compliance with the scale of the plan or map. They represent the most large objects: forests, meadows, arable land, lakes, rivers, etc. Using scale marks on a topographic map, you can determine not only the location of an object, but also its size. In addition, the similarity of the contours of the depicted terrain objects and their orientation are preserved on the map. Areas of figures or are painted over , or filled in with appropriate symbols.

Off-scale symbols or point symbols . This group consists of objects whose areas, due to their small size, are not expressed on the scale of a plan or map. Such objects include geodetic points, kilometer posts, semaphores, road signs, stand-alone trees, etc. By off-scale conventional signs impossible judge the size of the depicted objects of the area. However, in each of these signs there is a certain point that corresponds to the position of objects on the ground. So, for example, for some conventional signs this point is located in the center of the sign (triangulation point, wells, fuel depots), for other signs - in the middle of the base of the sign ( windmills, monuments) or at the top of the right angle at the base of the sign (mileposts, road signs).

Out-of-scale conventional signs for depicting relief elements are used in cases where not all relief elements can be expressed by horizontal lines - curved lines connecting points of the terrain with the same marks. For example, mounds, pits, stones, waste heaps are depicted by conditional off-scale signs with the use of explanatory conventional signs in some cases.

Linear symbols depict objects of the terrain that have a significant length and a small width. Such objects are car roads, railway lines, pipelines, communication lines and power lines. The length of such features is usually expressed at the scale of the map, and their width on the map is shown out of scale. The position of the linear symbol on the map corresponds to longitudinal axis of symbol.

Explanatory symbols are intended for additional characteristics of the terrain objects depicted on the map. For example, the width and nature of the road surface, the number of households in settlements, the average height and thickness of trees in the forest, etc.

The same object on plans of different scales will be depicted differently: on plans of large scales it will be expressed by a similar figure, and on plans of small scales it can be indicated by an off-scale symbol.

Definition 1

Cartographic symbols- symbolic graphic designations that are used to depict various objects and their characteristics on cartographic images (maps and topographic maps).

Sometimes symbols are called map legend.

Types of conventional signs by scale

Depending on the scale, $3$ groups of conventional signs are distinguished:

• scale (areal and linear);
• off-scale (point);
• explanatory.

With the help of areal scale signs, extended objects are displayed on a map scale. Scale signs on the map allow you to determine not only the location of the object, but also its size and shape.

Example 1

Scale marks are the territory of the state on a $1:10,000,000 scale map or a reservoir on a $1:10,000 scale map.

Linear conventional signs are used to display objects that are significantly extended in one dimension, for example, roads. Consistent with the scale on such signs, only one dimension (in which the object is the most extended), while the other is off-scale. The position of an object is determined by a conditional or explicit center line.

Out-of-scale point symbols are used on maps to represent objects whose dimensions are not expressed on the map. The largest cities on the world map are displayed as off-scale signs - dots. The actual placement of the object is determined by the main point of the point symbol.

The main point is placed at off-scale signs as follows:

• in the center of the figure near symmetrical signs;
• in the middle of the base for signs with a wide base;
• at the top of the right angle, which is the base, if the sign has such an angle;
• in the center of the lower figure, if the sign is a combination of several figures.

Explanatory signs are intended to characterize local objects and their varieties. Explanatory signs may indicate the number of railroad tracks, the direction of the river.

Remark 1

On large-scale maps, the signs of individual objects are indicated separately, on smaller-scale maps, objects of the same type are grouped and applied with one sign.

Conventional signs by content

1. signs and signatures of settlements;
2. signs of individual local objects;
3. signs of individual relief elements;
4. transport infrastructure signs;
5. signs of hydrographic network objects;
6. signs of soil and vegetation cover;

Signs and signatures of settlements

On maps at a scale of $1:100,000 and larger, all settlements are indicated along with the signature of their names. Moreover, the names of cities are applied in direct capital letters, rural settlements - in lowercase letters, urban and suburban settlements - in lowercase oblique letters.

Large-scale maps display the exterior outline and layout, highlighting major highways, businesses, prominent knowledge and landmarks.

Example 2

On the $1:25 \ 000$ and $1:50 \ 000$ scale maps, the type (fireproof or non-fireproof) of the development is displayed in color.

In the figure below - signs of settlements used on maps different eras.

Signs of individual local objects

Separate local objects, which are landmarks, are drawn on the map mainly with off-scale signs. It can be towers, mines, adits, churches, radio masts, remnant rocks.

Signs of individual relief elements

Relief elements are marked on the map with appropriate signs.

Remark 2

An object of natural origin is represented by lines and signs in brown.

Transport infrastructure signs

The objects of transport infrastructure displayed on topographic maps include the road and railway network, structures and bridges.

When plotted on a map, paved roads (motorways, improved highways, improved dirt roads) and unpaved roads are distinguished. All paved roads are plotted on the map, indicating the width and material of the pavement.

The color of the road on the map indicates its type. Highways and highways are applied in orange, improved dirt roads in yellow (occasionally orange), unpaved country roads, field, forest and seasonal roads without color.

Signs of objects of the hydrographic network

The following elements of the hydrographic network are depicted on the map - the coastal part of the seas, rivers, lakes, canals, streams, wells, ponds and other bodies of water.

Reservoirs are plotted on the map if their area on the image is more than $1 mm^2$. In another case, a body of water is applied only because of high importance, for example in dry areas. Objects are labeled with their name.

The characteristics of the objects of the hydrographic network are indicated next to the signature of the name of the object. In particular, they indicate in the form of a fraction the width (numerator), depth and nature of the soil (denominator), as well as the speed (in m / s) and direction of the current. Also indicated along with the characteristics of hydraulic structures - ferries, dams, locks. Rivers and canals are mapped in full. In this case, the type of display is determined by the width of the object and the scale of the map.

Remark 4

In particular, at a map scale of more than $1:50,000$, objects less than $5$ m wide, at a map scale of less than $1:100,000$ - less than $10$ m, are depicted by a $1$ line, and wider objects by two lines. Also, $2$ lines designate channels and ditches with a width of $3$ m or more, and with a smaller width - one line.

On large-scale maps, blue circles indicate wells, the letter “k” or “art.k” is placed next to it in the case of an artesian well. In dry areas, wells and water supply facilities are shown with enlarged signs. Water pipelines on the maps are shown by lines with blue dots: solid lines - ground, broken lines - underground.

Land cover signs

Often, when displaying land cover on a map, a combination of scale and off-scale symbols is used. Signs denoting forests, shrubs, gardens, swamps, meadows, nature are large-scale, and individual objects, for example, free-standing trees, are off-scale.

Example 3

The swampy meadow is displayed on the map as a combination of conventional symbols of a meadow, bushes and a swamp in a closed contour.

The contours of areas of terrain occupied by a forest, shrub or swamp are applied with a dotted line, except when the boundary is a fence, roads or other linear local object.

Forested areas are indicated in green with a symbol indicating the type of forest (coniferous, deciduous or mixed). Areas with forest growth or nurseries are plotted in pale green on the map.

Example 4

The figure below shows a coniferous tree on the left. Pine forest with an average tree height of $25$ meters and a width of $0.3$ m, as well as a typical distance between tree trunks of $6$ m. The figure on the right shows a deciduous maple forest with a tree height of $12$ m and a trunk width of with an average of $3$ meters.

Swamps are shown on the map with blue horizontal shading. At the same time, the type of hatching shows the degree of passability: intermittent hatching - passable, solid - difficult and impassable.

Remark 5

Swamps with a depth of less than $0.6$ m are considered passable.

Vertical shading in blue on the map indicates salt marshes. As well as for swamps, solid shading indicates impenetrable solonchaks, broken shading indicates passable ones.

Colors of symbols on topographic maps

The colors that depict objects on maps are universal for all scales. Black dashed marks - buildings, structures, local objects, strong points and boundaries, brown dashed marks - relief elements, blue - hydrographic network. Areal signs of light blue color - a mirror of waters of hydrographic network objects, green color - areas of tree and shrub vegetation, orange color - quarters with fire-resistant buildings and highways, yellow - quarters with non-fire-resistant buildings and improved dirt roads.

Remark 6

On military and special cards, special conventions.

We all know what a legend is in the common sense. This is a legend, an epic, a story with fictional elements. But what is a map legend? Not everyone knows this until the end. Let's deal with this term.

What is a map legend?

In cartography, a legend is a table or list of symbols used in an atlas, accompanied by an explanation of those symbols. Such a system is not unified for all maps, but is standardized and mandatory for their topographic appearance.

Usually in atlases legend maps with conventional signs are located in free space so as not to hide any objects from the reader. If the publication is large, then a page is allocated for the map, or even several. Usually the symbols in the legends are grouped into thematic groups: settlements, roads, relief, climatic zones, plants and animals, industrial facilities and more. Also, any statistical or informational information can be placed here.

Symbolism of the legend

The symbols in this case are graphic symbols, which denote various objects, features of the area. The legend of a map of the world or a certain area helps to understand them. Without this, it is impossible to read the atlas correctly.

If you constantly work with cards, then you already understand some conventional signs logically. For example, if something is drawn that has a certain area, this object will be outlined by borders or even shaded from the inside. To depict what is not stretched on the ground, lines are used, certain point symbols.

The area of ​​this or that object is not taken approximate - its image is repelled from the scale. You will always find information about the latter in the legend of the map of Russia, the world, a separate zone or region.

The main requirements for conventional signs are that they must be simple, logically understandable and diverse. For this, for example, separate categories are executed by the cartographer in the same color and style both on the map and in the legend. You can also highlight something by choosing a specific font, its size. So, for example, megacities are indicated in capital letters, regional centers - in capital letters, small settlements - in small print. And in the legend it is already written how many inhabitants each spelling implies.

Another important requirement for the atlas is the readability of symbols not only in the legend table, but also on it itself. It is difficult to understand what is depicted if the conventional signs merge with general background, similar to each other, are drawn without regard to print quality. The cartographer also pays attention to whether the atlas will be color or black and white. In the first case, the variety and clear visibility of symbols for the most part achieved various shades, in the second - the diversity of images, forms, font.

Of course, it is more convenient for us to navigate the terrain as much as possible. detailed maps. But at the same time, overloading with symbolism can greatly complicate the reading of the atlas. To find out what this or that conventional sign concealed under itself, one has to turn to the legend from time to time, which is rather troublesome. Therefore, the cartographer must be able to be concise - to depict only what is necessary, to add the necessary details somewhere, to render an enlarged area. Otherwise, the map will turn into a difficult puzzle for the student, traveler or other reader.

Legend character groupings

As we have already mentioned, there is no harmonious uniformity in the world of cartography. Some unified symbols were adopted at international geographical congresses in 1909 and 1912. They installed the symbols of the legend, the so-called "Millionth International Map".

However, at the same time, the main groups of conventional signs can be distinguished:

• Digital lettering.
• Off-scale symbols.
• Signs for objects that are shown on the scale of the map.
• Linear conditional symbols - borders, highways, railways, coastal, connected lines, horizontal lines, etc.

Basic symbols

Having analyzed what the legend of the maps is, we saw that its main character will be the symbolism used on the depicted terrain plan. The most common signs are as follows:

What is a map legend? These are conventional signs that designate a particular object in the atlas, and their a brief description of. Quite strict requirements are set for such symbols in order to make the map readable and logical.