Law of the Sea

The Law of the Sea refers to a collective body of jurisprudence that has developed largely over the past three centuries. The fundamental question involved how much territoriality a state could claim over the sea, as an extension of its shoreline. Some European countries began claiming a “territorial sea” adjacent to their coastlines in the late 16th century, but no internationally recognized standard existed, and such zones were arbitrarily established. As European states became more involved in maritime commerce and exploration, the indeterminate character of the territorial sea led to frequent wars, especially between England and the Netherlands. The two countries fought four wars between 1652 and 1784, and one of the main causes of this extended string of conflicts was the struggle over control of shipping lanes, maritime resources, and territorial waters. By the beginning of the 19th century, a number of countries were claiming a stretch of water adjacent to their coastlines of three to four nautical miles, although some demanded a somewhat wider swath of water. No wars erupted from these conflicting claims, although disputes sometimes occurred. Most of these disagreements were resolved by bilateral or multilateral treaties, but it still remained the purview of any sovereign maritime state to declare and enforce the extent of its territorial waters—no universally accepted and recognized code governed such claims. The formation of the League of Nations in the wake of World War I led to greater efforts to establish global standards governing the seas, although few treaties were actually formalized, and the generally accepted limit of a three- to four-mile territorial sea was maintained. However, the relative stability brought about by this arrangement was shaken by the so-called Truman Proclamation of 1945, in which the United States asserted sovereign control over the resources of the continental shelf. The Truman Proclamation set in motion a cycle

Monsoon

Somewhat less than half of Earth’s population lives in monsoon zones and is highly dependent on monsoon precipitation for agricultural production. Religious festivals are timed to the onset of the wet and dry monsoons. Failure of monsoon rains or flooding from monsoon rains raise the specter of famine. Monsoon is a commonly used but misunderstood term. One might hear an acquaintance talk about “today’s monsoon” out of a Great Plains thunderstorm, but the term was not originally used to convey the sense of prodigious wetness. The word is derived from the Arabic mausam meaning “season” and referring to the seasonal reversal of wind directions in the arid Arabian Sea and western Indian Ocean. Sailors were able to reliably time their trading trips by this expected feature of the atmosphere. Pronounced seasonal wind reversals are present in much of the world, but the term monsoon now most properly refers to a climatic regime of reversal of seasonal winds bringing alternating seasons of wetness and dryness. The monsoon regions of the planet encompass wide swaths of the tropics and subtropics and are, classically, experienced in Asia and parts of central Africa. From December through February the primary wind direction is northeast to southwest, while June through September brings the reversal of this flow. The former period is quite dry while the latter is prodigiously wet.

Monsoons have their roots in the tropical and subtropical parts of the global wind and pressure belts. The shifting declination of the vertical sun causes parts of the global circulation to expand, contract, and change latitudes. Monsoons are features in the tropical and subtropical portions of the planetary circulation. Differential heating of land versus water is the simplest explanation of the wind reversals. Continents heat more dramatically in the summer than do oceans and these temperature gradients set up wind gradients transporting air from the oceans to the continents. In the winter, the thermal gradients reverse and cause the surface air to reverse flow. Continental air is dry while oceanic air is moist and associated with great amounts of precipitation. The monsoon is most prominent around Asia because of the immense size of the Asian land mass and the complexities of its coasts.

The air flow high in the troposphere is known as a partial cause of monsoons. The subtropical jet stream is most active in the winter season because of the great temperature difference between equator and poles. With its mean winter position to the south of the Himalaya Mountains and Tibetan Plateau this strong upper flow complements the cooling of the Asian continent and keeps the oceanic air out of the continent. In the summer season, the subtropical jet weakens and jumps to the north of these southern Asia highland areas and the oceanic air is allowed to incur into the continent.

Middle Latitude Cyclones

A middle latitude cyclone (MLC) is a large disturbance that lasts for several days, and is the most significant weather-maker of the middle latitudes. This storm is also known as an extratropical cyclone or a wave cyclone. The term “cyclone” denotes a central low pressure with closed isobars. Middle latitude cyclones, hurricanes, tornadoes, and dust devils are cyclones of various causes, sizes, and strengths. In particular, a middle latitude cyclone is the largest of all cyclones and is a complicated admixture of the polar front jet stream, air masses, and fronts. The MLC is a seminal concept in understanding the middle latitude weather of our planet and was first proposed by Norwegian scientists shortly after World War I.

The origin of an MLC, called cyclogenesis, is directly related to energy imbalances between equator and poles. As such, the strongest MLCs are usually reserved for the winter season when the imbalance is greatest. Near the polar front jet stream, cold, dense air is to the polar side and warm, less dense air is to the tropical side. These air masses do not mix unless they are energized by a disturbance in the polar front jet stream. As such a disturbance passes overhead an air aloft diverges (pulls apart horizontally). This creates a surface low pressure zone into which air converges and rises to make cloudiness and precipitation. However, this is not all: the convergence of air into the surface low makes the polar and tropical air masses push on each other thus creating active fronts. The strength of an MLC cyclone is largely dependent on the upper air flow. If the flow aloft strengthens, divergence is favorable for evacuating air from the surface cyclone and strengthening the storm. If the upper divergence decreases, the surface circulation is damped. The paths of MLCs are readily forecasted because they are steered in the direction of the air in the polar front jet stream.

A MLC experiences several stages as it crosses the United States. At first, tropical and polar air masses encounter each other with neither being the aggressor. An upper disturbance in the polar front jet stream causes a center of low pressure (the cyclone), a cold front, a warm front, and an incipient wave. With the passage of a few hours the MLC forms a large wave and there is a circulation established (a counterclockwise spiral toward the center in the Northern Hemisphere). Within the wave is, typically, a maritime tropical air mass while pushing the cold front along is a continental polar or Arctic air mass. It is at this mature wave stage that the cyclone is strongest and the most severe weather is expected. With the passage of more time, an occluded front starts to form. The occluded front occurs because cold fronts travel faster than warm fronts. As cold air overtakes the maritime tropical air within the wave, the warm air is forced aloft ending the air mass contrast along that part of the front. Occlusion progresses southward from the cyclone’s center in the Northern Hemisphere. As the cyclone occludes its strength abates and all that remains is residual cloudiness and light precipitation. The cyclone has “died” but, before this, much polar and tropical air has mixed and the boundary between the polar and tropical air is established in another position.

Mental Maps

Spatial information about the world, carried in one’s mind. Studies in behavioral geography have shown that all humans utilize mental maps, although to varying degrees and at different levels of ability. The formation of a mental map is generally a subconscious process and begins at an early age. This “brain cartography” provides a means of organizing our activities, recognizing our “home” terrain, and negotiating through places that are new and unfamiliar.Without the ability to form mental maps, humans would lack the capacity to venture forth to locate food (done today at a local supermarket, but only a few thousand years ago in a field or forest), find a mate, and other vital behaviors—in other words, the formation of mental maps is crucial to human survival. The average person forms a mental map through experience—as one explores an unfamiliar landscape, various spatial “cues” or markers are noted and recorded, providing points of reference that later can be recalled when encountered again. The process works exactly the same way, whether one is exploring a highly organized and complex urban environment or a pristine wilderness. Street signs in a city provide the same type of mental benchmark as an unusual looking tree, a spring, or a pile of rocks does in a forest—both allow an individual to organize and traverse a new spatial environment. As that environment is repeatedly encountered, new features are added to the “map,” and the level of detail increases.

Scholars of behavioral geography are especially interested in mental maps, because such maps form the core of spatial perception and reveal a great deal about how people view the world around them, as well as the world at large. The mental maps one carries may play a significant role in the formation of cultural identity, as well as how other regions are perceived. Studies have shown that nation-states emphasize the development of a more detailed domestic mental map among students in their public school systems than mental maps they form of adjacent countries, even in students who live adjacent to international boundaries. Views of regions that are not precisely defined provide interesting insight into spatial perception. For example, the boundaries of the “Deep South’ in the United States vary considerably, depending on where the question is asked. The mental maps of the “South” that the average resident of Alabama holds will differ markedly from that held by a resident of Nebraska. Interestingly, many people form mental maps not only about places they have encountered, but also about places they have not yet been to. These sorts of maps may be formed from media reports or other sources of information that are not geographical, yet in many cases people form a spatial concept from them. Some research has found, for example, that a significant number of people link spatial extent to the frequency of hearing information about a place, so that the greater the times a country is mentioned in the media, for example, the larger it is perceived to be.

Megalopolis

A term from urban geography that identifies a large, contiguous urban region. The word was first used by the French geographer Jean Gottman in describing the strip of urbanization running along the eastern seaboard of the United States from Boston, Massachusetts, toWashington, D.C. Another term for this concentrated zone of urban development is BosWash, an amalgamation of the names of the terminal cities. The label of “megalopolis” is now applied to any large urban conurbation anywhere in the world, and many such locations may be identified. Typically, a megalopolis is characterized by a large population, dense and sophisticated transportation systems, a concentration of industrial and service economic functions, and numerous urban problems, such as higher levels of pollution, greater congestion, and loss of green space. A 2005 study by Robert Lang and Dawn Dhavale identified 10 “megapolitan areas” in the United States. To qualify for this label, an urban corridor had to include a combined population of at least 10 million by the year 2040, occupy a similar physical geography, represent an identifiable cultural region with a common sense of identity, and be “linked by major transportation infrastructure,” among other criteria. Lang and Dhavale identified 10 such urban regions within the United States, and highlighted the economic, demographic, and political power such mega-cities represent. According to their study, approximately twothirds of the U.S. population lives within the boundaries of a megapolitan area, and 80 percent of the members of the U.S. House of Representatives have some portion of their congressional district lying within such a region.

The toponymy of the 10 areas delineated by the research of Lang and Dhavale reveals both the location and identity of the megalopolis. The “I-35 Corridor,” for example, is an emerging strip of urban development that extends from San Antonio, Texas to Kansas City, closely following the interstate highway that links these cities and a string of others lying in between. The “Valley of the Sun” is a megalopolis centered on Phoenix, Arizona, while “Piedmont” is the urbanized region emerging along the southeastern flank of the Appalachian Mountains. But the development of such “super cities” is not limited to NorthAmerica, of course. In Japan the Taiheyo Belt is an enormous urban concentration of more than 80 million people, running from Tokyo on the island of Honshu to the northern end of the island of Kyushu, connected by high-speed trains. The Taiheyo Belt represents one of the most dense concentrations of industrial and financial development in the world, all focused in a strip of territory the size of southern California between San Francisco and Los Angeles. Indeed, megalopoli appear to be emerging in many corners of the planet, and it seems likely that such enormous urban clusters will dominate the urban landscape of the future. This will present new challenges in the form of transportation infrastructure, integration and governance, environmental degradation and quality of life, and very likely others that have yet to appear. Changes in the cultural landscape, as well as in cultural identity, also seem inevitable as the megalopolis

evolves into the defining feature of urban life.

Medical Geography

Medical geography is the study of the spatial aspects of disease and human health. Like almost all phenomena associated with human activity, the incidence of disease exhibits a spatial pattern. By analyzing such patterns, a causal relationship between disease and behavior, or disease and environmental factors, may be discerned. Such recognition may then be used in combating the spread of the malady, and limiting the infection rate if the disease is contagious, or lowering the incidence of the sickness if the environment or human behavior is responsible for the disease. The individual often credited with founding this subdiscipline of the field is Dr. John Snow, an English physician who treated patients suffering from cholera during a severe outbreak in London in 1854. Snow acquired data on known victims of the epidemic and used these figures to plot the number of deaths from the disease on maps of the city. He thereby determined that many of the victims lived quite close to a water pump used as a water source, located on a busy thoroughfare called Broad Street. At the time, little was known about how cholera was transferred from person to person, and Snow theorized that the source of the infection was the communal water pump. He called for authorities to shut it down, and once it was closed, the number of deaths and rate of contagion dropped abruptly. Snow had stopped a serious killer in its tracks by applying geographical techniques to the study of disease.

Map Projections

The basic problem in displaying the real world, which appears in three dimensions, onto the two-dimensional surface of a map is addressed by the map projection. Because there is no way to accomplish this transformation without distorting at least one of the basic elements indicated on the map (angles, areas, distance, and direction), a means of projecting the information contained on the map must be selected. Although no map can show all of these basic relationships in their true dimensions, many projections are able to display at least one of them accurately and truly. For this reason, it is quite important that when using a map for a specific purpose, attention is paid to the projection of the map. Geographers and others working with maps must be aware of the limitations of the projection they employ to display their data, and how it may affect the spatial relationships they wish to analyze. In theory, a limitless number of map projections might be constructed, and with the development of computer cartography, many options are readily available. Today, with a click of the computer mouse the projection of a map and the information it contains may be changed instantaneously, an option made available to geographers only in recent years. A number of projections have limited application and are used only for highly specialized work. However, over the past several centuries, some projections have become “standard” in the sense that they are used more than others for certain purposes such as comparing relationships between areas, navigating on the high seas or during transoceanic flights, or other types of uses.

Natural Resources

Natural resources are those materials that are present in, on, or above Earth have economic value and are not the product of human endeavor. They constitute the raw materials that are extracted by activities in the primary sector of the economy or they may represent substances that are vital to human existence or quality of life, such as water, forests, or other types of ecosystems. Natural resources may be found in abundance and in multiple locations, or they may be quite rare and obtainable in only a few places. Furthermore, the value and utility of natural resources arise and change with modifications and advancements in technology. Today, there is no global demand for whale oil, and in fact it is quite difficult (and often illegal) to obtain in most parts of the world. But in the early 19th century the oil obtained from whales was a common fuel source for lamps and also had applications in the processing of wool. Today this once vital natural resource has been all but completely replaced by other substances, and for the most part has lost both its value and utility. On the other hand, before the industrial age, rubber, both natural and synthesized, had virtually no utility and little value. Since the advent of the automobile the demand for rubber has exponentially increased, making it a valuable natural resource indeed. More recently, new sources of energy like sunlight and wind would not have been considered “natural resources” in the traditional sense of the term, but now may be classified as such since they are now used in the production of energy.

Access to natural resources is vital to economic development. In the modern global economy, the primary sources of energy remain hydrocarbon fuels, primarily petroleum, coal, and natural gas. In 2007 these so-called fossil fuels accounted for about 86 percent of global energy usage, a startling figure that highlights the essential function such resources serve in maintaining economic standards and driving growth. Countries that lack deposits of these fuel resources must acquire them if they are to remain competitive, and the geopolitics of energy is the subject of study for many scholars. In a similar fashion, strategic metals, many of which are found in only a handful of locations, are vital to modern industrial economies, and are therefore quite valuable and sought after. The country of South Africa, for example, controls 80 percent of the world’s production of platinum, a highly valuable metallic ore that has many industrial applications, as well as being used for jewelry.

There are a number of ways of classifying natural resources. In broad terms, resources may be separated into renewable and non-renewable resources. Renewable resources are those that are not fundamentally destroyed in their consumption, although they may be degraded or change form to a certain extent; or they are materials that may be reproduced by nature in a relatively short period, even if they are consumed or destroyed by use. An example of the first type of renewable resource is water, which may be drunk by humans or animals, used to irrigate farmland, piped around machinery to cool it, or employed for many other purposes, yet is not destroyed or consumed in the process. Wood is an example of the second kind of renewable resource. It may be destroyed through use (burning wood for heat, or to make charcoal, for example), but if managed properly, it is renewable because new tree seedlings may be planted and new wood produced indefinitely.

Natural Hazards

A type of event, triggered by forces in nature, that has the potential to cause significant loss of life, damage to property, and other natural hazards. To be considered a “natural hazard” the event cannot be caused by human activity or negligence, i.e., a fire caused by a burning cigarette in an apartment building has the potential to cause multiple deaths, but it is not a natural hazard because the fire is the result of human carelessness and is preventable. On the other hand, a similar fire caused by a lightning strike would be considered the result of a natural hazard. 

Natural hazards are generally not preventable, and in some cases cannot even be predicted with any level of accuracy, a characteristic that makes preparation for and response to this class of hazards particularly difficult. If a natural hazard results in an event that causes significant loss of life and/or property damage, the event is termed a natural disaster. In the United States, relief from the damage resulting from natural hazards is addressed initially by local and state agencies, but if the consequences of the event are severe enough to warrant additional assistance, the governor of a state may request federal disaster relief by declaring a specific location or group of locations (usually cities or counties) “disaster areas” and requesting assistance from the Federal Emergency Management Agency (FEMA).

The financial losses and cost in lives of natural hazards can be enormous, with a single significant event resulting in billions of dollars of damage and thousands of deaths. Geographers have become increasingly interested in recent years in the study of natural hazards, especially in the locational analysis of the patterns associated with the occurrence of hazards, and in the spatial aspects of response to such events.

Organic Theory

In general, the term “organic” implies a relation to a living organism. In social science theory, this usually means a philosophical attempt to conceptualize some process as analogous to the life cycle of a living creature. It is often associated with the philosophy of Social Darwinism, a theory popularized in the 19th century that applied the precepts proposed by Charles Darwin regarding “natural selection” and “evolution” to human social, cultural, and political systems. But in fact, organic theories date to a much earlier era, and suggestions of the application of “organic” qualities to human institutions and behavior may be found as far back in history as the writings of Aristotle and Plato, and continue well into the Middle Ages in the work of Niccolo Machiavelli and Ibn Khaldun. Organic theory has been frequently directed at the origin and nature of the state as a means of organizing political space and regulating activity. The concept reappeared in the philosophy of Friedrich Hegel at the beginning of the 19th century, who clearly had a significant influence on a wide group of scholars and writers. Hegel proclaimed the state as an “ideal” means of organizing political authority and made clear that he regarded the state as a living thing, when he stated directly that the “state is an organism.” To Hegel, the state could be examined and understood only in this context. In the discipline of geography, this concept was adopted in the positions of many early theoreticians in political geography in the late 19th and early 20th centuries.

Ocean Currents

Earth is a water planet and the world ocean is always in large-scale motion, slowly rearranging its waters over large extents of latitude and longitude. Whereas tides and waves are vertical motions, ocean currents are horizontal. Currents can be directly forced by surface wind or occur more slowly and deeply because of gradients of temperature, pressure, and salinity. Humans have long been knowledgeable about currents because they are large and readily associated with fishing conditions and navigation. More recently, science has connected changes in currents with global changes in weather and long-term changes in climate. 

There is a known geography to the major currents of the world. Because of the wind emanating outward from the subtropical highs of the global wind and pressure belts, kinetic energy from the fluid that is the atmosphere is imparted to the much denser fluid of the ocean. In that the subtropical highs are semi-permanent features of the atmosphere, this means that air blows from preferred directions over large stretches of oceans for days and weeks at a time. The ocean water starts to move in response though not as fast or in exactly the same direction because of the increased force of friction and the correspondingly lesser Coriolis effect.

The main geographic regularity that can be observed is the presence of oceanic gyres, immense circulations around ocean basins. These gyres have a clockwise flow of water in the Northern Hemisphere and a counterclockwise flow of water in the Southern Hemisphere. This means that there is considerable water being transported from tropical to polar latitudes and vice versa. The main subtropical gyres are joined by Equatorial Countercurrents in the Pacific and Indian oceans.

The strong trade winds on the equatorward side of the gyres cause the westward motion of the water and the piling up of water level in the eastern parts of these ocean basins. The higher water in the east literally runs downhill into the linear area of light and variable Intertropical Convergence Zone winds, and it is this eastward-moving water that is the Equatorial Countercurrent.

Push-Pull Concept

A theory that attempts to identify the motivational factors that drive migration. The concept was introduced by Everett Lee in his article, “ATheory of Migration,” first published in 1966, in which Lee attempted to codify the various considerations that a potential migrant might take into account as a basis for relocation. Lee based his ideas on the earlier work of Ernest Ravenstein, a British geographer who in the late 19th century articulated a series of “laws” of migration. Ravenstein was the first scholar in the industrial age to attempt a systematic study of migratory flows, both within countries and across international boundaries. Ravenstein focused much of his study on the actual movement of people and less on the forces that convinced them to shift location, however, and Lee sought to address the causation of migration. He divided the array of pressures to migrate into two broad categories: those that would “push” an individual or group to migrate, and those that instead would “pull” migrants to a new place. Lee holds that these factors working either alone or in concert, and at various levels of intensity, are responsible for inducing the movement of human beings across space.

The “push” factors that Lee describes are all negative aspects of remaining in the home country that a migrant will seek to avoid and often flee from. Lee did not claim to have produced a complete listing of these, but his compilation contains the majority of common reasons behind the “push” to migrate. These range from life-threatening situations such as famine, threats to one’s life, and natural hazards and disasters, to matters of personal life choices or to seek better economic opportunities, such as finding a suitable spouse or a higher-paying job. 

Other push factors are poor quality of life, especially low standards of housing and medical care, loss of farming opportunities due to desertification (indeed a major cause of migration in the Sahel region of Africa), actual or feared religious and political persecution, and other reasons. Any of these causes and others suggested by Lee are sufficient to convince an individual or group to move to another location, although the friction of distance may prevent migration until a certain threshold of tolerance is exceeded, at which point migration will take place. Push factors by themselves will suffice to instigate a migratory flow, but pull factors also usually play a role in the decision to migrate. These are positive aspects of the target location, whether it is a foreign country or territory, or another place in the country of origin. These include better living conditions, better health care or treatments unavailable in the home country, political or religious freedom, greater opportunities of marrying, etc. Pull factors therefore frequently complement push factors. Some pull factors are related more to amenities; for example, moving to a region that has a more comfortable climate or beautiful scenery (a common factor in the migration of retirees in developed countries). Although rather general, the push-pull concept provides insight into why migration occurs.

Primate City

A primate city is one that dominates the urban landscape of a country in terms of demographic weight and economic function. The term stems from an article published in the Geographical Review by Mark Jefferson in 1939. Jefferson described what he called the “law” of the primate city in countries where the largest city held a dominant position over the second- and third-largest cities by a constant ratio. The validity of this “law” has been greatly weakened over the intervening decades, but the general concept of a single urban place holding much greater significance demographically and economically than other cities in a state is still accepted and may be empirically demonstrated in numerous countries. If one extends the concept to include the phenomenon of the emerging megalopolis, found in many world regions as a single urban space, then these new primate “megacities” represent an urban dominance never before witnessed.

Many primate cities may be identified. Paris is more than eight times larger than the next largest city in France, and Mexico City is almost five times larger than Guadalajara, the country’s second most populous city. In the United States, a country with many large urban areas, New York is more than twice as large as Los Angeles. Such cities typically contain not only a large share of the country’s population, but also account for a disproportionate percentage of the country’s economic production. For example, the metropolitan area of New York produces over a trillion dollars of goods and services in an average year, a figure larger than many entire states in the United States. Furthermore, the city plays a magnified role in the country’s economy due to its hosting of the two largest stock exchanges  in the country, and because an enormous number of corporations have their headquarters in the city. The city also functions as a cultural center, serving as a capital for art, design, music, and theater. New York is somewhat unusual as a primate city in that it does not function as the national capital.

Precipitation

As part of the hydrologic cycle, water vapor is transformed into clouds. Clouds are common and, although in constant motion, usually cover about half of the planet at a time. Even so, precipitation is occurring over a small portion of Earth because most clouds do not produce precipitation. How and why precipitation occurs is vital in understanding the physical geography of Earth, because the precipitated water affects the surface lithosphere, biosphere, and hydrosphere.

Precipitation is triggered by one of two processes. The first is known as the warm cloud process and involves only water droplets (including supercooled water) above tropical locations. Cloud droplets collide and some of them coalesce to become large enough to fall out of the sky as rain. The cold cloud process (also known as the Bergeron process) takes place in middle latitude and polar clouds. The temperatures are below freezing and supercooled droplets and ice crystals coexist at temperatures between 0° and −40°C. The saturation vapor pressure is a bit higher over liquid water than over ice crystals and the net effect is that ice crystals grow by adding mass from the nearby droplets. The enlarged ice crystals become large enough to fall as snow.

The general term for water precipitated out of the sky is “hydrometer.” There are several types of hydrometers and their occurrences are governed by moisture supply, rise of air, and the environmental lapse rate underneath the clouds. Snow starts as snowflakes in clouds and falls through below-freezing air to the surface.

Plate Tectonics

Plate tectonics is the notion that Earth’s crust is composed of a number of huge, interlocking pieces that slowly move. This knowledge is not abstract nor useless in that plate tectonics provides us with insight as to why continents and ocean basins are shaped as they are, why large earthquakes and volcanoes are focused in the geographic patterns in which they are observed, and why Earth has its mountains, folds and faults.

One of the great scientific triumphs of the latter half of the 20th century was the proof and fleshing out of the implications of plate tectonics. This is a concept so grand that it was difficult at first for most scientists to believe it. Indeed, some of the early proponents were ridiculed. Whereas the notion of plate tectonics is a unifying concept, the topic of continental drift is the part of knowledge from which plate tectonics sprang.

In 1598, the Flemish geographer/cartographer Abraham Ortelius noted the “fit” between the Atlantic-fringing continents. In 1620, influential Sir Francis Bacon echoed this as continental coastlines on maps became better defined. Both these scholars left the subject without proposing a causal mechanism. In 1858, Antonio Snider-Pelligrini drew “before” and “after” maps of continents and stated that the continents had moved apart because the biblical flood of Noah restored a lopsided single-continent Earth to a more even configuration with several continents; this reasoning became untenable as scientists found increasing evidence that such a worldwide flood never existed.

Pastoralism

The practice of raising and husbanding domesticated quadrupedal livestock, typically sheep, goats, cattle, horses, or other animals. Pastoralism may be conducted either on a subsistence level, where stock are kept for the needs of the owner and family, or on a commercial scale, where large numbers of animals are herded on large tracts of land, eventually to be slaughtered and processed for the market. Many groups who are pastoralists are also nomadic and may engage in transhumance, a practice common in mountainous regions, in which herds of animals are moved between lower and higher elevations on a seasonal schedule. In other cases the migration of humans and animals involves a regular rotation among traditional grazing lands, which are abandoned once the animals have consumed most of the available vegetation. A key distinction between pastoralists and hunters and gatherers is that the animals associated with pastoralism are domesticated and live in close proximity to the herders, sometimes even sharing the same structure for shelter.

Non-commercial pastoralism is typically viewed in the context of cultural ecology as an adaptation to natural conditions that prohibit the development of complex agricultural systems. Conditions are either too dry (the Sahel region) or the growing season too short (northern Scandinavia, Siberia) to produce sufficient food for the population, and domesticated livestock then become the main source of calories in the diet. Moreover, the livestock when slaughtered may provide clothing, weapons and tools, and other items essential to the survival of the pastoralists. Pastoral groups may be classified on the basis of the dominant type of livestock they raise, or on the geographic region they typically occupy.

Rural Settlement

In general, a rural place or region is identified by a low density of population; a predominance of land used for agriculture, ranching, or that is undeveloped; and relative lack of urban places, especially those that occupy a large area whose economic activities and employment are concentrated in the secondary and tertiary sectors of the economy. The territory in a country that is precisely designated as rural often depends on the standards and definitions used by the government agencies of that specific country, just as is the case when considering urban geography.

Moreover, even countries that show a high level of economic development and hold large populations may also be predominantly rural—the United States Bureau of the Census identifies 95 percent of the United States as rural, and the proportion of rural territory in Canada and Australia is similar, although as in the United States, a large majority of the population living in these countries is urbanized. On the other hand, many lesser-developed countries have a majority of their people living in rural districts, with only a relatively small portion of the population considered residents of cities. 

Regardless of the world region in which they are located, most rural landscapes show distinct patterns of settlement, which are typically determined by environmental and economic factors, cultural practices, social relations, and sometimes the type of crop produced. The presence or absence of water may influence the spatial nature of rural settlement. In deserts and other regions where rainfall is scarce and agrarian production is dependent on surface water sources for irrigation, or on underground supplies from wells or springs, settlements are centralized around or near the source of water. These may be gathered at an oasis, where a single freshwater spring provides water for the human population, livestock, and usually a limited amount of cultivation. If local farm production is dependent on a lake or river to supply a system of irrigation canals, rural settlements tend to be located adjacent to the water source or to the central irrigation works. The construction and maintenance of irrigation canals, along with the equitable allocation of water, requires significant oversight and collective effort and results in a settlement pattern that is closely tied to the availability of water.

Rimland Theory

A perspective on geopolitics and international relations, presented as a critical response to the Heartland theory proposed by J. Halford MacKinder. The Rimland theory was the brainchild of Nicholas Spykman, a political theorist and professor of international relations at Yale University. Spykman was a proponent of realism in international relations, a view which holds that political states act solely to promote their own interests and agendas. Writing in the 1940s at the height ofWorldWar II, Spykman suggested that the Heartland theory put forth by MacKinder several decades earlier was flawed, in that it overemphasized the role of the Heartland in determining the balance of power in global relations. Spykman also drew heavily on the writings of the American naval strategist Alfred Mahan in constructing his theory.

Although his academic training was not specifically in geography, Spykman considered the discipline to be of the utmost importance in analyzing and understanding international relations and the dynamics of global power. The Rimland theory appeared in Spykman’s 1944 book The Geography of the Peace, published posthumously the year following his untimely death. He adopted the basic spatial framework of the Heartland theory, but made some changes in terminology. Spykman retains the concept of the Eurasian landmass representing a “Heartland,” but calls the region that MacKinder labeled the “inner” or “marginal” crescent the “Rimland.” He rejectsMacKinder’s characterization of North and South America, Australia, Japan, and Great Britain as lying in the “outer” or “insular” crescent, and instead simply terms this region the “off-shore islands and continents,” although he agrees with MacKinder’s view that for these countries sea power is of paramount importance, and represents the main means of projecting power. In the Rimland theory, the Heartland does not represent the pre-eminent seat of power that it symbolizes in Heartland theory. Rather, it is the Rimland that is the foremost seat of power and is the key to dominating the Heartland. Paraphrasing MacKinder’s summary of the Heartland theory, Spykman offered his own summary:

Who controls the Rimland rules Eurasia;

Who rules Eurasia controls the destinies of the world.

Remote Sensing

Geographers are keen in using fieldwork as part of their professional toolkits for understanding the world. Fieldwork can be quite laborious, costly, and—sometimes—dangerous. Since the middle of the 20th century when aerial photography became widely available, geographers have made frequent use of remote sensing. Remote sensing is a term that refers to a set of techniques by which the environment is studied. Electromagnetic radiation is sensed by devices as it is reflected, refracted, scattered, transmitted, and emitted by matter in the environment. Each feature of Earth and the atmosphere has a “spectral signature,” that is, the interaction of the various electromagnetic wavelengths with that feature. Thus, we are able to identify,measure, andmodel features that are not in physical contact with the features under study. 

There aremanymeasurement devices that are in direct contact with what they are measuring and so, by definition, are not remote sensing devices. A thermometer is not a remote sensing device for air temperature because its temperature readings are dependent on the collision of atmospheric molecules with the device. A thermal radiometer, however, can be mounted in a satellite and measure the temperature in the atmosphere it is not touching. Table 3 illustrates the types of remote sensing commonly used by geographers, primary wavelengths involved, and typical uses. The most well-known and commonly used form of remote sensing is photography. 

A camera contains film sensitive to light. The film is kept in the dark until the lens is opened to expose the film. The image is made permanent by developing it with chemicals. Aerial photography is of oblique and vertical types. Oblique photography is the perspective we see looking out of an aircraft window. Much more useful to the geographer is vertical photography in which the camera is pointed underneath the aircraft and features can be mapped and measured.

Religious Syncretism

Religious syncretism occurs when the characteristics of two or more faiths blend to alter one of the faiths, or to create a completely new religion. This is usually the result of cultural diffusion, when a new religious worldview encounters the established set of sacred precepts already present in a given region. The process of syncretization, or the incorporation of new rituals, dogma, or concepts, may be voluntary or enforced. The process of religious syncretism frequently leads to alterations in the sacred space of a location, as new religious structures may be built, or existing ones changed to suit the changes brought about by the integration of new beliefs. This may involve the establishment of entirely new sacred locations, or it may mean the use of previous sacred spaces, but with a modification of their former characteristics, relevance, or importance in the new religious system.

Religious syncretism is often viewed by at least some believers as a threat to the “purity” of religion, and an attack on orthodoxy and tradition. Those who support the syncretic process are sometimes labeled heretics and accused of undermining the principles of the faith. However, most faiths indicate at least some ideas or practices that have been borrowed from other religious traditions, and the process of religious syncretism may be so subtle and lengthy that it is not recognized by believers. On the other hand, some faiths have been specifically created on the basis of incorporating the “best” elements from others.

Rain Shadow Effect

A rain shadow is a landscape-induced, long-term relative lack of precipitation of an area compared to its geographic surroundings. Rain shadows exist because the landscape “gets in the way” of the horizontal flow of air. Air cannot reverse direction when it encounters significant topography. Thus, it must stop, flow over, or flow around the barrier; this has a significant influence on patterns of precipitation. The orographic effect is an enhancement of precipitation because of the rise of air over the topography. A rain shadow can be viewed as the muting of precipitation because of the landscape. Frequently, the orographic effect and rain shadows occur in tandem.

Precipitation occurs because air containing water vapor rises and cools. The air cools until it becomes saturated, clouds are formed, and then precipitation processes cause some of the water in clouds to fall toward Earth. One type of rain shadow occurs because of the strong descent of air. If stable air has been topographically lifted to the crest of a mountain, it will attempt to sink back to its original, unlifted altitude after it crests the mountain. It will undergo adiabatic warming at 10°C per every kilometer of descent because, even if originally saturated at the mountain crest, the air quickly becomes unsaturated. Adiabatic warming increases the air’s capacity to hold water vapor and decreases its relative humidity sharply away from saturation. Without a significant rise of air, the potential for precipitation is smaller and the area’s dryness enhanced by greater solar radiation due to the relative lack of clouds.

A second type of rain shadow is formed as moist air encounters topographic barriers but does not have the dynamics to rise over the barrier or divert around it. In this case the air pools in front of the barrier and the land in the lee of the barrier does not receive the moist air.

A third type of rain shadow is formed when air encounters higher terrain but is able to divert around it at low elevations. For instance, Pacific air encounters the Olympic Mountains in Washington State and is able to flow around them through the Strait of Juan de Fuca to the north and a near-sea-level lowland to the south. The result is that east of the Olympics—near the western reaches of Puget Sound—the precipitation is significantly less than in the mountains. Embedded within a regional climate of many cloudy days with light precipitation, the locals jokingly label this part ofWashington “the banana belt.” Port Townsend directly downwind of the OlympicMountains receives a bit over 65 cm (26 in) of precipitation. To the east of Puget Sound, Seattle receives nearly 100 cm (40 in) of precipitation because the air streams that have flowed around the Olympic Mountains are able to converge and cause the rise of air.

Sustainable Development

A philosophy and set of behaviors that strive to find methods of maintaining current quality of life while simultaneously minimizing the degradation of environmental and social systems to perpetuate these systems for future generations. The term “sustainable development” is sometimes generally associated with the stewardship of natural resources and preservation of wildlife habitats. Certainly wise and judicious use of energy and other products, and maintaining a balanced approach to the exploitation of ecosystems, is one of the core goals of the philosophy, but the concept is considerably broader than just these objectives and extends beyond just environmental concerns. Indeed sustainable development is a holistic notion designed to achieve a state of equilibrium between development and conservation across the spectrum of human experience. Advocates of sustainability seek to avoid the pitfalls and degradational consequences of the tragedy of the commons, a situation in which a resource is mismanaged and potentially lost because of a lack of communal oversight and concern. Both raising awareness and implementing practice are vital to achieving sustainability, and the United Nations has been a strong proponent of the concept, especially through the vehicle of the UN Earth Summit meetings held in Rio de Janeiro in 1992 and Johannesburg in 2002. The meeting in Rio generated Agenda 21, a detailed set of objectives meant to promote and highlight the potential benefits of sustainability, as well as to articulate mechanisms for reaching an equilibrium of production and consumption economically, ecologically, and socially.

Supranationalism

A form of political organization that partially transcends the sovereignty of its constituent units, increases the permeability of their boundaries, but that falls short of becoming a complete federation, in that the states so incorporated retain a significant measure of political independence. A cluster of states that joins together to promote trade and economic development, or to enhance their collective security, is not necessarily a supranational group. To reach this distinction, a greater degree of integration beyond simply promoting mutual interests must be sought and achieved. Some commentators consider supranationalism to be a form of political globalization. 

The first use of the term in a legal document appears to be in the Treaty of Paris in 1951, which formally established the European Coal and Steel Community (ECSC), setting the stage for the creation of the European Economic Community (EEC) with the promulgation of the Treaty of Rome in 1957. After adding members steadily for several decades, the EEC became the European Union (EU) under the Masstricht Treaty in 1994. Other international organizations may be “supranational” to a limited extent, but to date the European Union remains the most ambitious example of supranationalism.

The motivation behind the drive toward supranationalism in the European region has several points of origin. In the aftermath of World War II European countries sought some mechanism beyond simple treaties to ensure a lasting peace on the continent and to avoid a repetition of the massive destruction of the first half of the 20th century. Economic integration was viewed as such a mechanism, because by tightening economic (and ultimately, political) ties, the basis for conflict would be undermined, a notion that is the foundation of economic peace theory in the field of international relations. This is made quite clear in the famous statement by the French politician Robert Schuman, in which he held that economic integration would make war “materially impossible” in Europe. 

In addition, some of the smaller European countries were at a disadvantage in competing against the larger economies and sought to cooperate as a larger, single economic space to be more competitive. This was the case with the Benelux customs union, formed in 1948 between Belgium, the Netherlands, and Luxembourg. The reduction of customs duties and other impediments to trade between the Benelux countries led to rapid economic growth and other benefits, and the Benelux union along with the ECSC provided the basis for further integration. The three Benelux states then joined with the larger economies of West Germany, Italy, and France in forming the EEC. The EEC was much more than a simple customs union, because from an early point it attempted to coordinate economic policy among its members, some of whom initially resisted what they viewed as efforts to erode their national sovereignty.

Stream Erosion and Deposition

Streams are predominant shapers of the terrestrial landscape. Main streams and their innumerable tributaries are responsible for much of the landscape we see. Even in arid areas, stream water can do significant work when available because of the lack of protective vegetative cover fostering increased surface erosion and runoff. In the absence of significant tectonic disturbance, the overall effect over very long amounts of time is to make the higher places lower by erosion and lower places higher thus “smoothing” the landscape. Within the immense time scale related to smoothing it is common for streams to produce hills, valleys, and canyons by lengthening, deepening, and widening their valleys.

The landscape has been given a simple classification vis-a`-vis stream erosion. The surface area drained by a stream is a drainage basin (or a watershed) and its boundaries are drainage divides. Drainage basins exist on vastly different scales and, because streams have tributaries, main streams are associated with the multitude of tributary drainage basins that are nested at various scales one within another. It is through the organization of drainage basins that the flows of mass and energy associated with streamerosion and deposition can be understood. Stream-produced landscapes are segmented into interfluves, valley sides, and valley bottoms. High ground dividing adjacent river valleys is known as an interfluve. At the highest elevation along an interfluve is a drainage divide. Interfluves can be many kilometers across or nonexistent in the case of drainage basins edged by steep mountains. The valley side is the increased slope down to the valley bottom. Valley sides can have slopes of only a few degrees from horizontal or be bluffs or canyon sides. The valley bottom is the surface along which a stream is eroding or depositing and can be negligible such as on a canyon bottom or many kilometers wide.

Squatter Settlements

Areas of dense, low-quality housing around many large cities in the developing world, usually formed by illegal occupation, or “squatting,” of unclaimed land. Squatter communities are created by the migration of poor, rural residents to cities who are drawn there by the push-pull concept, especially the allure of higherpaying jobs. Over the past forty years many urban areas in the developing world have witnessed a surge in new arrivals from the hinterland they serve, and the supply of local housing has simply been unable to keep pace with the increase in population. New residents have therefore been forced to build ramshackle sheds on unclaimed or public land. 

Globally, an enormous number of people live in squatter settlements, with some estimates running as high as one billion, and in some cities the residents living in such conditions may approach one-quarter of the population, although exact figures for the number of people living in local squatter neighborhoods are frequently difficult to obtain. In the Spanish-speaking countries of Latin America squatter settlements are locally referred to as barrios, while in Brazil a community of illegal residents is called a favela. The city of Sao Paulo, Brazil’s most populous city, has more than 600 of these settlements, and the United Nations estimates that about 26 percent of Brazil’s total population lives as squatters. In South Africa the local squatter settlements are called shanty towns.

The shanty towns found around South African cities have expanded exponentially over the past 20 years, due to the elimination of the laws that prohibited blacks from settling in many urban areas. Under the system of apartheid, the white-dominated government had created some squatter communities by forcefully relocating illegal residents to maintain racial segregation in urban areas; but as apartheid was dismantled, many rural blacks migrated to the cities and established new shanty towns. 

Regardless of where the squatter settlement is located, all such developments share some basic characteristics. Housing is inferior, often built haphazardly on unstable ground like the sides of hills and ravines. Building materials are usually scrap wood and sheet metal, cardboard and plastic. Most of the structures lack flooring, and frequently thousands of shacks, perhaps homes to ten thousand people, are constructed without any plumbing. Because the settlement is illegal and unplanned, in most cases streets are unpaved, narrow, and lack any naming system or other means of identification, just as individual residences have no numeral system of location. Running water is often available only at some distance, because water lines are usually not supplied to squatter settlements by municipal governments, and communal spigots are frequently the only source of water.