GEOGRAFIA

GEOGRAPHY. – In general, it is the science that studies the various parts of the earth’s surface.

It also includes those other disciplines which, although they do not have a geographical character, are considered useful for their points of contact, their relationships, and their common fields of research.

The task of geography is not so much to systematically coordinate facts and phenomena that manifest themselves on the earth’s surface as it is to localize these manifestations in relation to their extent—that is, the space they occupy—and in correlation with all the constituent elements of the landscape and environment. Landscapes and environments, when objectively described, result from the combination of natural and artificial elements, from the terrain as nature presents it for a given period of time and in a certain space, and with all the transformations brought about by human activity.

Given the ever-changing aspect of the earth’s surface, geography, as a scientific description of it, refers to the present geological period and therefore takes into account only the variations that the earth’s crust may have undergone in historical times.

Geographical research can essentially be carried out by employing various research methods: the principle of extent, i.e., research into the area over which a phenomenon extends on the earth’s surface; the principle of coordination, according to which the geographical study of a phenomenon presupposes a constant concern for analogous phenomena that may manifest themselves in other parts of the globe (E. De Martonne) and consequently creates for geography the tendency to scientifically classify the facts it studies; the principle of causality, i.e., research into the causes that determine the extent and distribution of a phenomenon on the earth’s surface, so that the historical consideration of facts constitutes a distinctive feature of modern geographical science; and the principle of correlation, according to which the various parts of the earth’s surface must be considered in continuous and constant relationships with one another, as if they belonged to a single organic body.

Geography is thus a synthetic science because the results acquired from other disciplines, which do not have a geographical character, are coordinated by it using methods that, through the above principles, ensure this science a distinct individuality in comparison with others.

II. THE EARTH’S SURFACE

By direct observation, only a very limited thickness of the earth’s crust—or rather the rocky envelope that forms the solid outer part of the earth—is accessible. Therefore, the meaning of the earth’s surface should not be understood in a literal or geometric sense, but rather as the thickness that is accessible to human experience and endeavor, as well as to organic life. The difference between the greatest altitudes and the greatest depths is insignificant compared to the average radius of the geoid (6,371 km). Nevertheless, since this solid, superficial thickness, within whose basins the oceanic waters lie, is the field of geographical investigation, both vertical and horizontal forms are fundamental elements of our study. These forms are subject to variability that generally does not appear because, during a historical epoch—a fraction of a geological era—no essential changes occur, or at least these escape human observation, which is “briefly lived.” And while the investigation of transformation processes interests the geologist for the interpretation of past phenomena and for the history of the earth’s evolution, it also interests the geographer because it is precisely from endogenic and exogenic actions and energies that the current forms of the earth’s surface result. However, the external description of forms is not sufficient unless it is complemented by an investigation into the physical events through which it is recognized that the earth’s surface is in a state of perpetual becoming.

Regarding the horizontal distribution of the earth’s crust, continental massifs are generally distinguished from oceanic basins. The former constitute the most stable zones of the earth, having been subjected for long geological periods only to general and uniform uplifting movements. The latter are areas covered by water, with a relief much simpler than that of the subaerial surface, and are perhaps considered such due to the incompleteness of our knowledge of marine bathymetry. The emerged lands and those found between the edge of the continental massifs and the oceanic basins constitute the continental shelves, while the zones of the earth’s crust characterized by particular vertical and horizontal mobility, which alter the original position of deposits, are called geosynclines; these are raised to considerable altitudes, forming the great corrugations of the lithosphere. Characteristic of geosynclines are their unstable equilibrium, strong gravity anomalies, and high seismicity. Continental massifs would consist of rocks that are, on the whole, lighter than those constituting oceanic basins, which, however, are more plastic than the former. Based on gravity measurements, geophysics admits that the earth’s crust floats, in a state of equilibrium, above a very dense fluid substratum. This is isostatic equilibrium (sial in secular hydrostatic equilibrium on the sima), according to which, by the principle of Archimedes, the weight of the immersed body is equal to the weight of the displaced liquid. From this comes A. Wegener’s theory (1880–1930) on the drift of the continents: the continental massifs, once united into a single block (Pangaea), surrounded by a single ocean (Panthalassa), would have undergone fractures and consequently splits into several parts during the Jurassic period, gradually drifting from their original positions. In addition to the geological and paleontological arguments that this theory provides, the surprising concordance of opposing continents is striking, especially the parallelism of the Atlantic coastlines. Geographical homologies, i.e., similarities in shape, were already noted by Francis Bacon (d. 1626) in the *Novum Organum*, where he refers to “similitudines physicae in configuratione mundi,” later by R. Forster, who observed how continents taper and end in a point to the south, and by L. Agassiz, O. Peschel, A. Penck, and Olinto Marinelli.

The emerged lands can be estimated at 149 million km², while the seas occupy 361 million, for a total of approximately 510 million km², corresponding to the entire surface of the earth, according to geodetic calculations. An important geographical fact is that in the current distribution of lands and waters, there is no regular arrangement; lands and seas are unequally distributed (there is a kind of opposition between continents and oceans, with the former grouped in the Northern Hemisphere and the latter in the Southern), and there is a singular antipodal arrangement whereby a continental mass is generally found at the antipodes of an oceanic basin, and vice versa.

III. GEOGRAPHICAL MAPS

Geographical science is an observational science; however, its object is such that it cannot be studied either directly or by means of a medium that reproduces what is peculiar to its object of study. Cartography is a completely autonomous art in its scientific and technical organization; it aims to represent, on a plane, all or part of the earth’s surface, creating not only ideal graphic expressions but also true metric expressions, from which most of the measurements of the territory under representation can be deduced. As a symbolic expression of phenomena as they are localized and distributed on the earth’s surface, cartography avails itself of the assistance that geodesy, topography, mathematics, statistics, and other sciences can provide.

The geographical map is, according to G. Caraci, «the plane representation of all or part of the earth’s surface, achieved by means of points, lines, and symbols, which are connected to one another and all together related to the represented area by positional, directional, and distance relationships determined as exactly as possible».

Maps, instruments and sources not only of research but also of description, are indispensable for a lengthy geographical study, and without them it would not be possible to organize the acquired facts. Plane images, reduced and approximate representations of the earth’s surface, their construction involves the solution of a geometric problem that seeks to reproduce, with minimal deformation, geometric constructions devised by mathematicians through various methods and called geographical projections. The coordinate grid, the foundation of the design, assigns to each point on the earth’s surface a corresponding point on the map. Due to the alterations that reality imposes, the projection will therefore be conformal (isogonic or orthomorphic), and the meridians and parallels will intersect at right angles, as on the sphere, preserving equal angles and maintaining a «shape» identical to that on the sphere, though with the drawback of not being able to maintain the same scale in every part of the map. The projection will be equivalent when the areas on the map correspond to the actual areas, though individual figures represented will undergo significant deformations, particularly toward the peripheral parts of the map. It will be an equidistant projection if, along certain lines, the map preserves lengths proportional to real distances. Since it is impossible to construct maps that satisfy all three of the above conditions, methods have been studied to create, through projections, conventional systems in which two of the stated conditions can be approximately satisfied. Thus, projections are distinguished into those made directly onto a plane and those obtained by means of an auxiliary surface (cylinder, cone); the former are azimuthal (horizontal) projections, the latter are development projections (conical and cylindrical).

The projection is chosen taking into account not only the content and purpose of the map but also, and above all, the extent of the region to be represented and its position relative to the geographical coordinates. Depending on the scale of proportion, that is, the ratio between graphic lengths and natural ones, maps are topographic, chorographic, and geographic. Depending on the nature of the phenomena they represent, maps are physical, orographic, hydrographic, political, ethnographic, demographic, economic, zoogeographic, phytogeographic, geological, etc.

Maps that aim to illustrate the worldwide distribution of the followers of various religions, as well as the atlases constructed for this purpose, are of particular importance.

An important problem in cartographic technique is the design and use of graphic signs and colors most appropriate to represent the reality of the earth’s surface effectively and clearly: hatching, shading, contour lines (isogonic) do not exist on the terrain, just as the difficulties in finding conventional signs that can, in the smallest space, immediately convey the idea of the phenomenon are well known.

The chromoplastic method, moreover, is tied to the customary practice of providing an overall image of the terrain with specific surface tints: blue for the sea, lakes, and rivers, green for lowlands, brown for elevations.

Representability varies depending on whether one is dealing with isolated objects or phenomena, or those with surface diffusion, quantitative or qualitative representations, phenomena that vary over time, or describe moving phenomena, etc. Depending on whether one is dealing with point objects, linear features, or those extended over an area, the methods of representation vary. In the quantitative representation of surface phenomena, reference is often made to isometric or isarithmic curves, lines passing through points on the earth’s surface where the intensity of a given phenomenon is the same. When these are not applicable, other widely used methods are mosaic cartograms (each division receives a color or hatching corresponding to the average value of the intensity that the phenomenon in question reaches in that region) and the dot system (in a number proportional to that which measures the absolute magnitude of the phenomenon to be represented). All maps are evidently approximate; the main causes of their imperfection are due to deformations arising from projection, inaccuracies in drafting, errors in surveying, and insufficient data. For surveys in vast and inaccessible areas, aerophotogrammetry has seen growing development in recent years. Even as a synthetic representation of a large number of factual data, the map cannot be considered the final outcome of scientific research.

IV. GEOGRAPHY IN ITS HISTORICAL DEVELOPMENT

I. In ancient times

The very etymology of the word shows that this science was born among the Greeks, where initially it meant the representation of the earth by means of a map. Later it was used to indicate a description not only on a map but also in words, of the entire then-known world, while the description of a limited region was called chorography, a term still in use.

Traces of primitive stages of knowledge appear in the *Iliad* and the *Odyssey* (1st millennium B.C.), while the merits of the first explorations of the Mediterranean basin belong to the Cretans (15th century B.C.) and their heirs: the Mycenaeans and the Phoenicians. The Greek expansion into Mediterranean lands (7th–9th centuries B.C.) later broadened the known horizon with results that for that time can be considered monumental.

It was Anaximander of Miletus, a pupil of Thales, who drew the first map of the world and systematized views about the earth. He created the image of the ecumene (the inhabited world) as an island surrounded on all sides by the Ocean, from which it had emerged through the reduction of water following the absorption of solar rays. Toward the end of the 6th century, the map of Anaximander was perfected by Hecataeus, who accompanied the work with a commentary describing a territory vaster than those previously studied, thanks to the knowledge acquired in the meantime of other regions: Scythians and Ethiopians, Celts and Indians were indeed the peoples placed by Hecataeus at the extreme limits of the ecumene. While Anaximander considered the fundamental object of geography the execution of maps, Hecataeus began to regard geography with a scientific and practical aim, as a description of lands and peoples. Herodotus (485–430 B.C.) was more a chorographer than a geographer, a more exact describer of particular lands than an elaborator of general syntheses, while Aristotle (second half of the 4th century) was dominated by excessively general and speculative tendencies, often at odds with the true reality of observed facts. Nevertheless, he pointed out new luminous paths in the astronomical and cosmological field, based on the sphericity of the earth.

The conception of the earth as a flat disk (of Anaximander, Hecataeus, and their successors) fell by the wayside during the 5th century with the school of Pythagoras, which arrived at the idea of its sphericity. Parmenides (513–440 B.C.) laid the first foundations of climatology, and the mathematician Eudoxus (or Eudoxius) attempted to measure the dimensions of the terrestrial globe.

Meanwhile the horizon of the world was still expanding: the Gulf of Guinea and the present-day Canary Islands had already been reached by the mid-5th century; the coasts of Gaul, Frisia, and the British Isles in the second half of the 4th century. Hanno and Pytheas were the most famous navigators of those times. The unsuspected extent of Asia was then revealed by Alexander the Great, who advanced from Asia Minor to Egypt and the Libyan desert, crossed the Persian Empire, reached the gigantic mountain barrier of Central Asia, Turkestan, and India. Dicaearchus of Messina, around 300 B.C., drew up a new map of the entire ecumene, based on the famous *diaphragma*, which can essentially be reduced to a central parallel running from west to east, supplemented by other secondary lines. Eratosthenes of Cyrene (c. 284–203 B.C.) wrote the first true treatise on geography, already containing elements of mathematical and general physics, descriptive regional geography with anthropic references, elements based on observations and factual reports, and presented with keen scientific discernment. The Eratosthenic approach drew into the field of geographical inquiry the study of all phenomena of the terrestrial globe. The era of Eratosthenes marks the zenith of ancient geographical science, which, with Aristarchus of Samos—a forerunner of Copernicus in constructing the heliocentric system—also reached daring conceptions regarding the solar system. Eratosthenes’ work was later continued by Posidonius of Apamea (c. 140–65), who wrote learnedly on the Ocean and its phenomena and devoted himself to physical geography, meteorology, and may even be considered a precursor of the most modern branch of geographical science: anthropogeography. He did not, however, attempt—as Eratosthenes did—a general synthesis of geographical knowledge. Among Eratosthenes’ opponents were one of the greatest Greek astronomers, Hipparchus of Nicaea (c. 190–125), and the Stoic Crates of Mallus.

While the Greek spirit inclined more toward pure scientific inquiry, the Roman spirit had more practical aims. The Roman conquests between the second half of the 2nd century B.C. and the early centuries A.D. provided reliable knowledge of Gaul, Germany, part of Ukraine, Britain, etc. Africa and Asia were traversed by Roman legions, and the extent of the ecumene was thus expanded by them. In the age of Augustus and immediately afterward, new syntheses of geographical thought were developed. At Augustus’ behest, the administrative reorganization of the Empire was undertaken (including itineraries, cadastral surveys, official descriptions of provinces, etc.), which facilitated the production of geographical works. Meanwhile, Agrippa, a great collaborator of Augustus, had a map of the entire known world, and in particular of the Roman Empire, engraved in a portico in Rome. Strabo, Pomponius Mela, and Pliny the Elder then wrote monumental geographical works and, among other things, set as the supreme goal of geographical science the relations between the natural characteristics of each country and the ethnic, social, and cultural conditions of individual peoples. From a descriptive standpoint, and as a general synthesis of the knowledge acquired by the end of the Augustan age, Strabo’s geography is indeed comprehensive, even if its approach is more limited, descriptive, and practical than the Greek Eratosthenic one.

At the beginning of the 2nd century A.D., we find Marinus of Tyre, whose principal work is known only through Ptolemy: a new map of the world. Ptolemy, however, was first and foremost an astronomer, who consolidated the geocentric cosmic system and popularized the value of the measurement of the Earth’s circumference (180,000 stadia), already accepted by Posidonius—a measurement corresponding to a terrestrial globe much smaller than reality.

In summary, it can be said that while Greek geography was expressed above all in graphic form (maps), in the Roman age the expository form prevailed. Yet at the foundation of both approaches lay the elaboration of observational data and empirical experience.

2. In the Middle Ages and the Renaissance

Geographical science suffered a broad interruption in the Middle Ages due to the fact that, with the breakup of the unity of the Roman state, relations between peoples were greatly restricted and new knowledge could not spread. Culture, almost entirely in the hands of the Church, was also imbued in the geographical field with a symbolism sometimes far removed from reality: circular *mappae mundi*, for example, often had Jerusalem as their center. Descriptions in this period are arid, often reduced to mere lists of countries, peoples, and cities. St. Isidore of Seville (563), the Venerable Bede (735?), Rabanus Maurus (9th century) wrote geographical works of no great value. In contrast, among the Arabs a rich geographical literature flourished, predominantly descriptive, but almost entirely unknown in the West, which knew only Ptolemy’s astronomical work. The scholastic period was based precisely on the physical principles of Aristotle and on Ptolemy’s cosmic system when studies of the terrestrial globe were resumed. Gervase of Tilbury (early 13th century), Alexander Neckam (1157–1217), Albertus Magnus (1206–80), Vincent of Beauvais (c. mid-13th century), Roger Bacon (1214–94), and Ristoro d’Arezzo, all indiscriminately based their work on Aristotelian-Ptolemaic doctrines, harmonious with the principles of Christian theology. Observation in the geographical field still did not exist, and the new knowledge brought to geographical science by John of Pian de Carpine, William of Rubruck, Oderic of Pordenone, and Marco Polo was met with incredulity.

A renewal can be found at the beginning of the 14th century in the field of cartography: nautical charts, regional maps, new circular world maps made their appearance, while descriptive geography remained unchanged until the 15th century. In this period Aeneas Silvius Piccolomini, who later became Pope Pius II (1458), compiled a geographical work (*Historia rerum ubique gestarum locorumque descriptio*), one of many examples of the then-current use of the term “cosmography.” Between the mid-15th and mid-16th centuries, Bartolomeu Dias, Vasco da Gama, Christopher Columbus, and Ferdinand Magellan, through their exploits, brought about a revolution in the world of geography: the sphericity of the Earth was universally recognized, the globe appeared vastly larger than could have been imagined, and the extent of the oceanic areas proved unimaginable. The study of and interest in nature revived, and in Humanism the long-forgotten works of Strabo and Ptolemy came to light again; cartography flourished anew, and figures such as Leonardo da Vinci, Fine, Gastaldi, Apian, and Mercator produced during the 16th century a great number of systems for representing the entire globe.

The revival of descriptive geography occurred with Sebastian Münster (1544). By the end of the 16th century, the Aristotelian system collapsed, and so too did Ptolemy’s cosmic system with Kepler, Copernicus, and Galileo, who laid the foundations of the new heliocentric system. Geography then appeared as a well-defined science, with its own aims and methods, particularly in a work by Varenius (1650): it was the first of the modern age, the geographical phenomena being clearly divided into celestial, terrestrial, and human phenomena—a division that has remained until our own day.

3. From the 17th Century to Modern Times

Mathematical geography was directed toward new approaches, and Sanson, Cassini, Delisle, and d’Anville upheld France’s standing in cartography with new world maps and maps of Europe and Africa. In the 17th century, geology began with N. Steno, founder of stratigraphy. In the 18th century, however, geography became an auxiliary discipline of the new economic, social, and statistical sciences, losing its character as an observational science and even, in part, its very content. With the 19th century, geographical science once again came to the fore, with the resumption of geographical explorations by Cook, Niebuhr, Pallas, and Bruce.

Alexander von Humboldt was the first true and great traveler-geographer, who concerned himself with terrestrial morphology, climatology, geobotany, and political geography. His comparative investigations henceforth formed the basis of geography. His contemporary, Karl Ritter, a methodical scholar, placed great importance on geography in education. But physical geography, most deeply explored by Humboldt, gained great importance after 1870, a period that saw the rise of countless geographical societies. Meanwhile, scientific explorations were advanced by Nansen (1893), Peary (1909), Ross (1842), and Amundsen (1911). All branches of geographical science were deepened, and the modern era of exploration began with the Challenger expedition. From the mid-19th century onward, European states understood the importance of possessing cartographic representations of their territories based on topographical surveys, and central meteorological offices multiplied their studies thereafter. The German Oskar Peschel (1826–75) remained one of the leading exponents of physical geography because he sought to restore geographical science to its naturalistic foundations; biogeography saw its position clarified through him. Meanwhile, geology had made very significant progress in many countries, and terrestrial morphology became a new branch of physical geography. Giuseppe Dalla Vedova (1834–1919) specified the proper tasks of geography, consisting in the investigation of the distribution and causal relationships among forms, phenomena, and living beings. Anthropogeography found its principal exponent in Friedrich Ratzel (1844–1904), who considered man and the manifestations of his activity, or more precisely, the influences of the environment on man.

At the beginning of the present century, geography was thus divided into two major branches: physical geography and anthropogeography, while astronomy and geodesy assumed the aspect of autonomous sciences. In the most modern times, explorations have been pursued with increasing intensity in both polar regions, in deserts, equatorial forests, mountain systems, the depths of the sea, and the highest atmosphere. Extensive exploration, however, has given way in recent times to more circumscribed and in-depth study.

Geography has today become highly complex, being based exclusively on facts of interdependence and mutual correlation. The description and classification of the various aspects of the earth’s surface now lead to defining geography as the science that studies and describes scientifically the landscape in the geographical sense (an abstract synthesis of the visible landscape), which is constituted by a small number or few groups of characteristic elements that, as a result of factors determined by climate, morphology, hydrography, vegetation, etc., delineate the great physiognomic forms of the earth’s surface.

Geographical-Planimetry of the Río de la Plata, drawn by L. Feuillée, engraved by P. Giffart.

A classification scheme of 43 landscape types (*Landschaftstypen*), proposed by Hassinger in 1933, is a simplification of a previous study by Passarge. Recently, in Italy, R. Biasutti (1947) described the principal types of terrestrial landscapes with reference to human life and activity. Today, geographical research in many states is directed by national bodies linked within the International Geographical Union, which promotes studies, research, and congresses. The major collaborative geographical works include: *La géographie universelle* (formerly directed by P. Vidal de la Blache); the *Handbuch der geographischen Wissenschaft* (directed by R. Klute); and *Geografia universale* (directed by R. Almagià).

In Italy, the bodies concerned with geography include: the Italian Geographical Society (Rome), the Society for Geographical Studies (Florence), the Military Geographical Institute (Florence), the National Committee for Geography within the National Research Council (Rome), the Hydrographic Institute of the Navy (Genoa), the Italian Touring Club (Milan), etc., all of which publish periodicals of scientific interest.

V. GEOGRAPHY AND ITS SUBDIVISIONS

In the current scientific framework, geography can be divided into several major sections.

4. Physical Geography (Physiogeography)

Physical geography may be defined as the science that studies the physical facts and phenomena manifested on the surface of the terrestrial globe (including the marine spaces), examined from the standpoint of their extent and reciprocal relationships. Knowledge of the shape, dimensions, position, and movements of the terrestrial sphere are indispensable general notions. The geographical consequences of these facts are manifold, and while one of the essential merits of Humboldt was to have, in the practice of observation, restored geography to the study of reality, the first element of success for E. Reclus and his happy influence on the spread of the taste for geography was his profound sense of that activity which animates the surface of the terrestrial globe with a kind of physical life.

It was only in the 19th century that terrestrial morphology was definitively established on a scientific basis. This, invigorated by the historical conception developed by the American geographer W. M. Davis and his school, is based on the continuous transformation of the forms of the surface, transformations that determine the distinction of relief into morphological types, classifiable according to the terrain and the modeling agent. The American morphological school was contested, especially in Germany, where emphasis was placed on the scientific, hence rational and comparative, description of the “landscape” (*Landschaft*), in its physical and anthropic aspects.

b) Oceanography. – It deepens research into the physical characteristics of the sea, the composition of waters and the distribution of salinity, temperature, transparency of waters; it deals with movements, submarine relief, sea level, bathymetric research; it studies the sea from a physico-chemical point of view (thalassography), the nature and development of living beings (thalassobiology). The first studies were by the Bolognese scientist Luigi Ferdinando Marsili (1658-1730), member of the Paris Academy of Sciences, who in 1725 published his *Histoire physique de la mer*. Since then this branch of study has seen considerable development both in Italy and abroad.

c) Meteorology. – It studies the properties of the atmosphere and the phenomena that occur within it; it investigates the general laws of atmospheric movements, as well as the formation and path of disturbances (dynamic meteorology). It studies the localisation of various meteorological phenomena, their interrelations, the influence of geographical conditions and the relationships of these phenomena with the life and development of animals and plants, as well as with public health and hygiene (climatology). It deals with studies relating to the free atmosphere, i.e., the layers of air not in contact with the ground (aerology). Meteorology thus covers the vast field of study of the entire aeriform mass surrounding the earth, of the average pressure exerted, of isobaric types, of temperature, of solar radiation, of hydrometeors; and it particularly investigates their functions and geographical distributions.

d) Seismology. – It deals with rapid and violent movements of the earth’s crust (earthquakes), produced by the passage of elastic waves transmitted from regions where a mechanical disturbance has occurred, as well as their effects, their distribution on the earth’s surface, their precursor and concomitant signs, seismic periods, microseismic movements and epeirogenic movements in general.

e) Volcanology. – It seeks to investigate the causes and effects of the surface layers (subaerial and submarine) of the globe, from which rocky materials from the deep layers are continuously or intermittently emitted (volcanoes). It identifies volcanic points, recognises in some similar phenomena secondary or pseudovolcanic phenomena, in others postvolcanic phenomena, and studies their distribution in the various regions of the earth.

f) Glaciology. – It concerns itself with glaciers, their structure, oscillations, cycles, movements, their geographical distribution; these studies, which began with scientific intent only at the end of the 18th century (by the Swiss geologist and physicist Horace Bénédict de Saussure [17.40-99]), then aimed to classify glaciers into types, to mark their characteristics, to study their parts, collecting and ablation basins, their recording, etc.

g) *Potamology.* – It studies the action of surface waters, rivers in particular, their elements, phenomena of erosion, deposition, etc., and the cycles of hydrographic basins.

h) *Limnology.* – It aims to study the nature, origin, and life of lacustrine basins, their relief, hydrology, soundings, bathymetric charts, movements, temperature, transparency, composition of waters, climatic and topographic influences, oscillations, etc. A subsidiary branch of oceanography, limnology shares the same problems, which it resolves using the same methods. Systematic studies in this field have developed considerably in recent times.

All branches of physical geography, even though forming an integral part of it, tend towards a certain autonomy; this, however, cannot disregard the fundamental consistency of physiogeography, the first part of geography proper, which, while drawing from human works, forms the basis of human geography, a branch in turn of organic or biological geography.

2. *Anthropic geography.* – It studies the distribution of humans on the earth’s surface and their activities; it investigates quantitative characteristics and variations (population density, distribution) and qualitative ones (differentiation into races [types], all of which are indices of series of facts of a physical, biological, and economic order that are interconnected).

Anthropic geography has the following subgroups:

a) *Ecological geography.* – It applies the principle of correlation, whereby man is influenced by the surrounding environment. Here geography makes use of ecology, properly concerning itself with the study of the relationships of living organisms with the surrounding world and of the peoples that make up present-day humanity, basing itself on linguistic, cultural, and social data of man as a modifier of the environment (through which one passes from a natural or unmodified landscape to a human or modified landscape), making use of mineral, animal, or plant resources.

b) *Economic geography.* – Drawing on commodity science and economics, autonomous sciences that deal in particular with the distribution of products and their commercial value, etc., it studies the utilisation of terrestrial resources by man. Parts of economic geography may be considered: commercial geography, which studies economic phenomena in relation to the soil (and which can be subdivided into production geography and consumption geography); and industrial geography, which is concerned with the distribution of raw materials and the possibilities of their transformation into finished products, with the exploitation of natural forces that depend on climatic and geomorphological factors.

c) Political geography. – It examines the modifications that man brings to the earth’s surface by living grouped in complex societies (States), determining borders, protective, developmental, and conservation works.

d) Ethnographic geography. – It investigates the causes and formative processes of peoples and their languages, the ways of human life, natural increase, and migrations.

A particular study of ethnographic geography is that of the distribution of religions, which, due to their complexity and influence on other human activities, have given rise to the formation of the geography of religions.

e) Geography of incitement. – It concerns all manifestations of human activity that modify the natural state of the earth’s surface, shaping the artificial landscape of civilisation in the distribution of large types: geography of settlements, geography of communications, geography of traffic. The geographical study of the city is given the name urban geography.

5. Aesthetic geography

One may also speak of aesthetic geography, of which A. von Humboldt, F. Ratzel, and G. Pennesi may be considered exemplars, in that, when describing the works of man in their regional coexistence, geographical subjects are treated synthetically and artistically, but at the same time with absolutely scientific rigour.

6. Tourist geography

A separate chapter could be constituted by tourist geography, which coordinates the geographical elements that represent the dominant factor in the problem of international and socially understood tourism.

7. Historical geography

It aims to highlight the changes that have occurred in past epochs. It also makes use of toponomastics, which is the glottological elaboration of the proper names of places and historical regions that denote particular natural and human conditions.

It is necessary, however, to draw on these sciences discreetly, without losing sight of the principle of localisation and extension, proper to geography, a principle which, if overlooked, would cause it to lose part of its character as an autonomous science.

To nourish oneself, to grow, to reproduce, to pass through phases of existence, and to die is common to all living individuals. That part of geography which claims the task of investigating the causes of the processes of transformation of plants and animals and their influence in the modifying work upon the surface of the earth constitutes biogeography.

8. Botanical geography

By botanical geography is meant the classification and distribution of plant formations across the globe.

For one to speak of botanical geography in the proper sense, it will be necessary to await the definition of the plant species given by Linnaeus toward the middle of the 18th century. The ancients were acquainted with notions regarding the origin and cultivation requirements of useful plants; but with Linnaeus, the first floras were compiled according to scientific criteria, which addressed the problem of plant conservation.

GEOGRAPHY – Icefall (serac) caused by a rock drop (Margherita Peak, Ruwenzori, National Park). Belgian Congo.

GEOGRAPHY – The main crater of Vesuvius – Naples.