reduced generalized depictions of the earth’s surface on a plane showing the distribution and the combinations and relationships of natural and social phenomena, which have been selected and described in accordance with the purpose of a particular map. It is not enough to define the geographic map as simply a drawing of the earth’s surface because these maps can represent the most varied natural and socioeconomic phenomena. Geographic maps are capable of communicating spatial changes in these phenomena over a period of time. Geographic maps are characterized by a particular mathematical law of construction (cartographic projections), by the depiction of phenomena by means of a special sign system, or cartographic symbols (cartographic signs), and by the selection and generalization of the phenomena being depicted (cartographic generalization). Geographic maps are normally regarded as graphic image-sign models. They have the basic features of models in general, such as abstraction from the whole for the investigation of the part, that is, a concrete area and concrete phenomena and processes; simplification, or disregard of the multiplicity of characteristics and relationships and the preservation of the most essential ones; and generalization, or singling out of common features and properties. These abstractions promote a deeper understanding of the phenomena depicted on geographic maps.
The first characteristic of geographic maps is that they are constructed by means of cartographic projections. This makes it possible to use the map to obtain correct data on the position, scale dimensions, and shape of the land objects depicted.
The second distinguishing feature of geographic maps is the use of cartographic signs as a special map language. These signs allow depiction of the earth’s surface with the desired reduction (that is, on the desired scale) in order to encompass at a glance the necessary area or even the entire earth’s surface. Moreover, cartographic signs permit reproduction on the map of those objects that are not expressed on the scale of the map because of reduction but should be shown because of their significance. The relief of the earth’s surface may be shown on the map by means of cartographic signs (for example, contour lines), that is, the unevenness in the terrain may be shown on a flat representation. Signs permit not only representation of the exterior (surface) of objects on geographic maps but also indication of their internal properties. For example, on a map of the sea it is possible to show the physicochemical properties of the water, the currents, the relief and soils of the sea floor, and much more. Furthermore, signs can show the distribution of phenomena that are not directly perceived by our sense organs, for example, magnetic declination, anomalies of gravity, and so on, and render graphically connections and relationships that cannot be directly perceived, for example, connections between the sources of raw materials and the enterprises that process them. Finally, signs permit the exclusion of insignificant aspects, as well as of the particularities and details characteristic of individual objects, and the isolation of their common and essential features—that is, they facilitate abstraction. For example, populated points may be characterized according to size of population and administrative importance without their layout being conveyed.
The third characteristic of geographic maps—the selection and generalization of the phenomena depicted, or cartographic generalization—is especially important.
Geographic maps are used to a greater or lesser extent in all spheres of human activity. Their importance as guides to localities is well known. In industrial, power, and transport construction they are the basis for exploration, planning, and carrying out of the engineering design. In agriculture, geographic maps are essential for land use management, land improvement and reclamation, and generally for determining the extent and best use of all land resources. Maps serve as important materials for instruction in and outside of school, for dissemination of knowledge about the world, and for raising the general level of culture. The thorough cartographic study of an area is very important in military affairs.
In the construction of socialism many national economic tasks require high-quality maps for their accomplishment. These tasks include the correct evaluation of geographic conditions, intelligent use and replenishing of resources, the development of plans for transforming nature, the efficient distribution of production forces, and the comprehensive development of economic regions. Maps used in scientific investigation not only give a graphic picture of the distribution of phenomena but also make it possible to identify the laws of this distribution. For example, geographic maps showing the geological structure of terrain serve to clarify the laws of distribution of mineral deposits. Finally, geographic maps are indispensable for the study of spatial interrelationships and the development of phenomena and, therefore, can be used in prediction.
The cartographic representation consists of a number of geographic elements determined by the subject and purpose of the map. For example, the elements of detailed maps of a locality (topographic maps) are the waters and the relief of the terrain, the vegetation and soils, the populated points, the lines and means of communication, the state and administrative boundaries and centers, and also certain industrial, agricultural, and cultural objects. Additional diagrams and texts, which make it easier to use the map, are placed in the margins and unused portions of the geographic maps. These include the map’s legend (a compilation of the cartographic signs used on the map with the necessary explanation); diagrams for measuring distances, angles, areas, the coordinates of particular points, the steepness of slopes, and so on; and the reference information on when the map was compiled, the sources used, and so on. Sometimes the margins of the map are also used for profiles, diagrams, tables, and textual information, all of which clarify and supplement the cartographic depiction itself.
Widely used are general-purpose geographic maps, on which the primary object to be represented is the earth’s surface itself together with the objects located on it. Other maps are called thematic maps. These give a very thorough and complete picture of some element (or elements) that is included in the general-purpose geographic maps (for example, relief of the earth’s surface). They may also show phenomena that are not found on general-purpose geographic maps, for example, the geological structure of an area and climatic conditions. Furthermore, there are different types of thematic maps, such as geological and climatic ones.
Thematic maps fall into two main categories: (1) maps of natural phenomena or physical-geographic maps and (2) maps of social phenomena, or socioeconomic maps (demographic, economic, cultural, political-administrative, and historical).
The subdivision of maps according to their purpose should be distinguished from the thematic classification of maps. Subdivision by purpose is the singling out of special-purpose maps designed for the needs of particular groups of users and for the solution of specific problems. Of this type are maps for such purposes as education, tourism, navigation, and planning. Specialized maps may be either general geographic maps (for example, tourist maps) or thematic maps (for example, school maps showing climate, soil, or economic distributions). Some groups of special-purpose maps are so specific that they are sometimes regarded as a distinct class of thematic maps called technical maps, including maritime navigation maps, flight maps, and planning maps.
In practice the classification of geographic maps according to territorial feature, that is, spatial scope, is widely used. This classification distinguishes maps of the world as a whole, of oceans and seas, of continents and large parts thereof, and of states, regions, and districts. Taken separately these classifications do not adequately encompass the full variety of maps. Therefore they are often used conjointly: classification according to territorial feature is ordinarily selected as the primary classification, and under its heading maps are divided according to theme and, further, according to purpose.
Geographic maps can also be distinguished according to their thematic breadth. For example, some climatic maps restrict themselves to one meteorological element, such as temperature or precipitation, while others include several elements, for example, air pressure and wind. Some maps describe climates in their totality. It is customary to designate as particular or branch those maps having a narrow theme, in this case particular climatic maps; maps giving a full description of the phenomenon are called general, in this case general climatic maps. Many maps show several phenomena simultaneously, that is, they combine them, and each phenomenon is given its own cartographic symbol, taking into account the mutual relations of the phenomena. These are multibranch maps, and they are called all-inclusive maps. An example of this type is the synoptic map, which combines all basic meteorological elements.
Geographic maps differ by the degree of generalization of their content. There are maps that use nongeneralized or little generalized symbols, for example, those that depict meteorological elements at a particular moment. Others use very generalized symbols, for example, those showing average monthly or even annual temperatures, computed from data covering many years.
Maps singling out and showing particular elements of nature, population, economics, and culture, as well the properties and characteristics of these elements, are called analytic maps. The greatest degree of generalization is found in synoptic maps, which describe phenomena as a unified whole by combining a number of symbols and using them jointly (merging them). An example of this type is the general climatic map, on which climatic regions are designated by an aggregate of several symbols (depicting such phenomena as temperature and precipitation) without these concrete symbols being represented. Synoptic maps can be said to generalize a number of particular maps. In practice there are maps with the most varied combinations of concrete and generalized symbols and analytic and synoptic characteristics. For example, many general-purpose economic maps use the analytic method of cartography for industry and the synoptic method for agriculture.
Maps constructed on the basis of insufficient data, especially when their purpose is to interpret observed facts or phenomena, may be hypothetical in nature and significance (either wholly or in part). An example is the mapping of different climatic regions of the world. The accumulation of new data makes it possible to verify, compare, and refine hypothetical maps made earlier.
The value of geographic maps depends not only on their data being complete, precise, and up to date but also on their underlying scientific principles and ideas. These principles and ideas may be progressive or outdated, correct or erroneous. For example, V. V. Dokuchaev developed a classification of soils for soil maps that was based on the natural factors involved in soil formation. Dokuchaev juxtaposed this view to the incorrect notion that soils were earthy rocks related to surface geological formations.
The simplest cartographic drawings were evidently known already in primitive societies. The most ancient cartographic depictions that have survived to the present time belong to the peoples of the ancient East (Babylon and Egypt) and China. Cartography achieved its greatest successes under the slaveholding system in classical times. Greek scientists made the first geographic maps based on cartographic projection that took into account the earth’s spherical form. In medieval times the flourishing of seafaring (in connection with the great geographic discoveries, the colonization of America, and trade with the East Indies and China) and the navigational needs arising from this led to the creation of many maritime maps. The development of cartography in this age was also dictated by the formation of large feudal-absolutist states, which needed dependable geographic maps to rule extensive territories. In the 19th century military-topographic surveying was widely used to compile detailed maps of a locality. Topographic maps were used to facilitate the control of troops, and they made it easier for armies to take into account the disadvantages of the terrain and to utilize its advantages during combat. Later these maps proved indispensable for engineering exploration and planning—roads, hydraulic-engineering projects, and so on. The differentiation of the sciences was another important stimulus for the development of cartography. Thematic maps began to be enlisted extensively for studying the distribution of different natural and social phenomena and for investigating their spatial laws, relationships, and determining factors. The need for thematic maps grew rapidly when the corresponding branches (for example, geology) began to serve practical work. The importance of thematic maps increased even more in the planned socialist society.
Phenomena may be studied and investigated more extensively when maps on different themes are used jointly. This determines the significance and development of comprehensive cartography, which involves making a series of comparable and mutually supplementary geographic maps and comprehensive atlases.
Because of their graphic and concise qualities, geographic maps are an indispensable means for preserving, transmitting, and obtaining new information on our planet and its separate parts—land and oceans—on geographic conditions and natural resources, and on population, economics, culture, and even historical development. The sphere of application of geographic maps is continuously expanding, which leads to the development of new types of maps and also to improved methods (including automatic methods) of making and using them.
REFERENCESSalishchev, K. A. Kartografiia. Moscow, 1971.
50 let sovetskoi geodezii i kartografii. Moscow, 1967.
Tematicheskoe Kartografirovanie v SSSR. Leningrad, 1967.
K. A. SALISHCHEV