Solar Energy

Solar energy is a renewable energy source in the form of radiant light from the sun. The term renewable solar energy refers to a broad range of technologies and techniques for capturing and utilizing this energy. In one hour, approximately 440 exajoules (EJ) of energy from the sun reach the Earth’s outer atmosphere. This is only slightly less than the estimated world population’s energy consumption from primary energy sources, such as biomass and fossil fuels, in an entire year. The Earth’s atmosphere, land surfaces, and oceans absorb a fraction of this incoming radiation, resulting in an increase in atmospheric, oceananic, and land mass heat, in addition to water evaporation.

These heat and evaporation processes in turn drive the Earth’s water cycle and produce atmospheric phenomena, including wind and weather patterns. Plants convert solar energy into chemical energy through the process of photosynthesis. Energy from the sun is critical to processes that sustain life on Earth. Directly capturing and utilizing even a small fraction of this vast energy source would offset fossil fuel consumption, which in turn would decrease the greenhouse gas (GHG) emissions that contribute to climate change.

Solar Energy Availability

Thermonuclear reactions in the sun result in the emission of radiation or light in all directions into space. The Earth intercepts a small fraction of this emitted radiation. At the top of the Earth’s atmosphere, the amount of radiated power from the sun remains fairly constant, at 1,361 watts per square meter (W/m2), varying only slightly throughout the year by plus or minus 3.5 percent because of the eccentricity of the Earth’s orbit around the sun. As this solar energy enters the Earth’s atmosphere, some wavelengths of this light are absorbed, scattered, or reflected back into space by different molecules, such as the gases and water vapor in the atmosphere. For example, a process known as Rayleigh scattering results in the blue appearance of the sky. On clear days, with little cloud cover, the radiated solar energy reaching a flat surface on the Earth can exceed 1,000 W/m2; however, on cloudy or overcast days, this power can be reduced to less than 100 W/m2. Cloud cover, aerosols, dust, smoke, and suspended water droplets all reduce the transmittance of the atmosphere and decrease the amount of solar radiation reaching a given location.

For terrestrial solar energy applications, the amount of energy that falls on a given surface is of primary concern. The orientation of a surface relative to the incoming sun’s rays must be considered when evaluating the solar energy available for a given application. The total solar radiation available to a surface at any orientation is a combination of two components: direct beam radiation and diffuse radiation. Because the incoming solar rays are nominally parallel, geometric relations can be used to estimate the amount of beam radiation available to a given surface. The surface’s available direct beam radiation is related to its latitude, the tilt of the Earth on its axis (which depends on the day of the year), the time of day, the slope of the surface, and the orientation of the slope in the east–west direction. Maximum beam radiation on a clear day occurs when the incoming solar radiation is perpendicular to the surface of interest. Diffuse radiation refers to radiation that is scattered and reflected from the atmosphere, clouds, and the ground to a particular surface.

The estimation of diffuse radiation availability depends upon the orientation of the surface, the scattering potential of the atmosphere, and the reflectance properties of the ground. On cloudy days, and when the surface is shaded from direct beam radiation, diffuse radiation is the primary source of solar energy availability.

Because the solar energy available at a specific location depends on many factors, historical data is often used to obtain more accurate estimates of energy availability during an average day. Solar energy availability can be estimated based on data collected from pyrheliometers and pyranometers. Pyrheliometers are instruments that track the sun and measure the available direct-beam radiation. Pyranometers obtain data on the total solar radiation or the diffuse solar radiation available to a fixed surface. Using historical data from such instruments located near a proposed installation site provides a more accurate measurement of the solar energy capture potential at that location. Such data can be modified using geometric relations and empirical observations to estimate the solar energy availability on a surface at any orientation.

Renewable Energy

According to the International Energy Agency, renewable energy is energy that is derived from natural processes that are replenished constantly. In its various forms, it is derived directly or indirectly from the sun, or from heat generated deep within the Earth. Included in the definition is energy generated from solar, wind, biomass, geothermal, hydropower and ocean resources, and biofuels and hydrogen derived from renewable resources. Renewable energy sources from natural energy sources such as sun, wind, waves, and tides have developed rapidly in recent years and have been used widely around the world as an alternative-energy system.

Renewable energy is considered one of the viable options to meet the challenge of achieving sustainable development and conserving natural resources that have been depleted because of the rapid growth in population, urbanization, and fossil fuel consumption while addressing the issues of energy security. Renewable energy has been widely considered an indispensable basis of sustainable energy systems, as electricity generation from renewable sources helps in reducing greenhouse gas (GHG) emissions, contributing to sustainable development and addressing climate change over the past decades as compared to electricity from conventional fossil fuels. 

Renewable-electricity generation capacity, including large hydropower, reached an estimated 1,140 gigawatt (GW) worldwide in 2008, with a total share of about 18 percent—of which 15 percent was from hydroelectricity and 3 percent from new renewables such as small hydropower, modern biomass, wind, geothermal, and biofuels. According to Renewable Energy Network 21 (REN 21), about 19 percent of global final energy consumption came from renewables in 2008, with 13 percent from traditional biomass used for heating, 3.2 percent from hydroelectricity, and a small percentage—about 2.7 percent—from the new renewables.

Apart from the environmental benefits, renewable energy has also been playing an important role in alleviating poverty and enhancing the development of remote regions through offering opportunities for work and social advancement of underemployed and disadvantaged segments of the population. However, their adoption has been mainly driven by impending environmental and energy security considerations arising from the use of fossil fuel–based energy (coal, oil, and gas) and the fact that fossil-based energy sources are finite.

Geothermal Energy

Geothermal energy is a renewable resource that is generated by natural processes within the Earth. Since prehistoric times, humans have enjoyed the recreational and perceived therapeutic properties of surface geysers and thermal hot springs. It has also been used to produce electricity on an industrial scale for more than 100 years. Geothermal energy provides a viable, sustainable, lowcarbon alternative to fossil fuels. Furthermore, the potential global energy production capacity of the Earth’s exploitable geothermal resources far exceeds both current and predicted future primary energy demand. However, in 2010, geothermal energy production comprised less than 1 percent of total global primary energy consumption.

The concept of geothermal energy raises some important questions: What is geothermal energy and under what conditions can it be exploited? What are some direct and indirect strategies for harnessing geothermal energy? What are some of the benefits and limitations of geothermal energy? And finally, what are the prospects for future development of this abundant and valuable energy source?

Geothermal Energy Basics

Over 99 percent of the Earth’s mass is extremely hot—above 1,830 degrees F (1,000 degrees C). In general, temperature increases with depth. The core of the planet, which is about 2,174 mi. (3,500 km) in radius, is composed of a solid iron inner core and a superheated liquid outer core that generates a magnetic field. The inner and outer cores are enveloped by another region called the mantle, which is about 1,800 mi. (2,900 km) thick. The mantle, in turn, is enclosed by an extremely thin and largely impervious outer crust (12–40 mi. or 20–65 km thick in continental areas, less in ocean regions), which in relative terms is analogous to the skin of an apple. In most places, the outer crust blocks a significant amount of heat from rising to the surface. However, there are some locations, such as a space between tectonic plates or active volcano systems, where the outer crust is unusually thin, permeable, or cracked, and heat can rise close enough to the planet’s exterior to allow human exploitation. Commercially exploitable resources are generally 1.8 mi. (3,000 m) or less below the Earth’s surface.

Besides heat and close proximity to the Earth’s surface, exploitable geothermal systems also require water and permeability. Hot water or steam is sometimes trapped in permeable rock formations, forming geothermal reservoirs below layers of impermeable crust. In some cases, these reservoirs can be accessed via geothermal wells; in other situations, the hot water or steam may seep to the surface naturally. It is also possible to artificially introduce water into a field of fractured hot rock where it is heated and then extracted by a production well.

Biomass Energy

Biomass energy is produced by extracting volatile gases, primarily methane, from organic materials such as wood, switch grass, corn stalks, or municipal solid waste. The variety of methods and levels of efficiency for extracting the gas are extensive. Biomass energy production, either for direct combustion of the gas or electric power generation, has been utilized widely for decades, but recently, large-scale production of biomass energy as a substitute or enhancement for traditional carbon fuel sources has received a great deal of investment and experimentation. Traditionally, a winter fireplace produces biomass energy from wood.

What the new biomass energy industry adds is mass production of energy for use in the economy as well as residential comfort. Gas from biomass sources can be conditioned (cleaned) and injected into existing or new gas lines. Its more frequent use is in combined heat and power (CHP) installations, particularly at landfill sites, for generating electricity. These more recent applications fill a double purpose, in the same vein as the much more recognized solar and wind generation, by both producing energy and reducing greenhouse gas (GHG) emissions into the atmosphere.

Methane, the primary biomass energy source, is rated by the International Panel on Climate Change (IPCC) as 21 times as warming in the atmosphere as carbon dioxide (CO2), the most abundant GHG. When a biomass energy project can extract and combust methane, the potential warming affect is significantly lower than if the methane escapes into the air—even though burning methane produces CO2 along with water:

CH4 + 2O2 = CO2 + 2H2O

Feedstocks and Production Technology Biomass developments must pair feedstock with technology. Applying the wrong technology or process to a biomass source will be unproductive and waste money. Some technology is still being tested, but several are proven and in common use. The most common, reliable, and profitable technology for extracting methane energy is anaerobic (without oxygen) digestion. Retention of a liquid slurry of organic biomass in a storage container for a period, usually, 21–30 days, will allow naturally occurring bacteria to digest the hydrocarbons in the material and produce methane. The bacteria work best in a moderately warm environment, around 98–100 degrees F (36–37 degrees C), and are self-generating. With care, digesters will produce a sustainable, predictable stream of gas for years.

There are many types of organic feedstocks for digesters. The content of the feedstock determines the quantity and quality of biogas production. For centuries, small farms in central Asia have deposited manure from their animals into pits and captured the methane for heating and cooking. Today, thousands of operational digesters produce commercial quantities of gas from dairy and hog manure, waste from farm operations, and even commercial fields of convertible feedstock such as grasses and fibrous plants.

Wastewater (sewage) treatment plants in developed countries employ digesters for reducing pollutants in water before returning it to the environment. The digesters flare excess digester gas that is not used for heating the digesters. This flare gas has become a credible source of bioenergy and can either generate electricity for the power grid or be conditioned for injection to the gas grid. Digesters are attractive technology because they produce a purified dry cake of nitrogen-rich fertilizer, as well as the remaining liquid fertilizer after the biogenesis process is completed.

European enterprises have built pilot plants using dry biomass technology in which large quantities of industrial, commercial, and municipal solid waste can be ground into fine particles and processed to produce the proper moisture content for combustion in boilers or gasifiers.

Often, the best use for such dry biomass is in the form of pellets for ease of storage and shipment. Dry biomass has some of the advantages in efficiency and reduced pollution of biogas, but it is still in its infancy for large production for the energy market. It is an especially attractive power source in densely populated urban areas because it is reduced to a much smaller quantity of ash and debris that can be disposed of in a landfill.

Much effort is being invested in improving pyrolysis of organic feedstock. Pyrolysis occurs when organic materials are heated in the range of about 662–932 degrees F (350–500 degrees C) in a closed container that prevents oxidation. At high temperatures and depending on the fuel, light oils can be produced, as well as biochar, a soil enhancement much sought after in the Amazon region; charcoal; activated charcoal for filters; and other valuable products.

Pyrolysis has the advantage of eliminating infectious (pathogenic) organisms in the biomass, as does anaerobic digestion, producing a clean gas for use in power generation. However, the multiple stages in the process of producing biogas through pyrolysis have so far been uneconomical. Very large pyrolytic plants are in use for enhancing the power production of coal-fired generators, and in northern Europe, pyrolytic plants provide power from wood. Currently, the capital investment required for large, complex engineered plants for pyrolysis reduces a number of economical pyrolysis applications.

Bioenergy

Renewable bioenergy is derived from diverse sources and in multiple forms: gas, electricity, and liquid fuel. The energy is released by combustion of organic matter that contains carbon compounds. Significant questions surround the production of bioenergy, including the level of greenhouse gas (GHG) emissions released by bioenergy facilities and the displacement of other economic products by the expansion of bioenergy sources. Although any carbon fuel, including coal, petroleum, and natural gas, is organic; bioenergy refers to the alternative, renewable sources that are not as harmful to the atmosphere and are not depleted through use. Most discussions of bioenergy also anticipate production that does not require mining or drilling.

Bioenergy sources include (1) anaerobic digestion of many materials, such as animal and human waste; (2) biomass processing, as in the pyrolysis of wood chips; (3) algae production of oils or chemicals, including fuels; (4) chemical conversion of carbohydrates, such as sugar from corn or sugarcane into ethanol; and (5) direct combustion of such fuels as cosmetics oils or food waste. The most common product of the decomposition of organic substances is the gas methane (CH4). 

Methane is the most important component of natural gas from wells and provides the majority of the heating and much of the electric power generation in industrial countries. Methane in natural form is trapped in many locations, including peat bogs, ocean sediment, and coal. For the most part, renewable or alternative-energy policies refer to the diverse ways to produce methane under controlled conditions from natural materials, rather than from drilling wells.

A very important concern in regard to global warming is the potential for uncontrolled release of methane from these natural reservoirs, such as the Siberian peat bogs, directly into the atmosphere. A large increase in methane in the atmosphere would stimulate further global warming, perhaps inducing a cycle of warming–release–warming. The most significant alternative or bioenergy objective is to control the combustion of methane into less harmful carbon dioxide (CO2) and water.

Rainfall Patterns

A rainfall pattern describes the distribution of rain geographically, temporally, and seasonally. The tropics receive more rainfall than deserts on a more regular basis. Cooler places like the poles receive no rainfall as the moisture is converted to snow before it falls to the ground. Rainfall occurs more often during particular times of the year, creating rainy seasons. In other seasons, rainfall is scant. Worldwide, rain-fed agriculture is planned based on rainfall’s natural pattern. Water storage, irrigation networks, and urban water-supply systems are designed according to the average annual rainfall. A significant amount of rain on a continuous basis for a long time increases the possibility of flood and subsequent disaster to infrastructure.

No or little rainfall for a longer period (years) in an inhabited area could lead to drought and famine. Changing rainfall patterns are a consequence of global warming, which causes a change in ocean thermohaline circulation. The world’s agriculture, especially third-world agriculture, depends upon seasonal rainfall patterns. Recent erratic changes in rainfall patterns lead to low agriculture production, thus creating food insecurity for everincreasing world populations. Untimely floods, droughts, and famine are the consequences of these unassuming patterns.

Global Warming and Rainfall Patterns

Global warming leads to a near-term collapse of ocean thermohaline circulation, a global ocean circulation pattern that distributes water and heat both vertically through the water column and horizontally across the globe. Because of this collapse, warm surface waters move from the tropics to the North Atlantic and extra-warm water surfaces in the Pacific Ocean surrounding the equator.

Thus, western Europe, some parts of Asia, and many parts of the Americas become warmer than average and some parts of Europe become rapidly cooler. El Niño and La Niña are examples of this phenomenon. The latest deviant trend is generating dramatic weather impacts such as rapid cooling in some parts of the world and greatly diminished rainfall in agricultural and urban areas. The United Nations Educational, Scientific and Cultural Organization and other studies found that changes in rainfall pattern can be attributed to shifts in the global wind pattern. These shifts are because of changes in ocean surface temperatures.

The effect of human activity on surface vegetation is also causing rainfall pattern variation. Widespread deforestation in parts of Africa and Asia is causing scarce rainfall and subsequent drought. Global warming affecting rainfall pattern variability is a commonly accepted phenomenon among the world’s scientific community. More precipitation is occurring in northern Europe, Canada, and northern Russia, but less in swaths of sub-Saharan Africa, southern India, and southeast Asia. A Canadian research team found in 75 years (1925–99) of rainfall data analysis through 14 powerful computer models that the Northern Hemisphere’s midlatitude (a region 40–70 degrees north) received increased precipitation, which corroborates with the change in thermohaline circulation.

The models also showed that in contrast, the Northern Hemisphere’s tropics and subtropics (a region between the equator and 30 degrees N) became drier, while the Southern Hemisphere’s similar region became wetter. This study was conducted for rainfall patterns over land. Time and again, researchers worldwide have proven that natural pattern rainfall is good for plant growth, while variable rainfall patterns lead to lower amounts of water in the subsurface level of soil (in the upper 30 cm). Variable rainfall patterns also cause plant diversity in particular areas, indicating that weeds grow rapidly with variable rainfall. The significance of these changes is evident from recent large-scale, worldwide failure of crops, rangelands, and water-supply systems.

Mass starvation in the Sahel region of Africa is stark proof of this. Some argue that changes in rainfall patterns are unfounded because of a lack of instrumental records for a long duration. However, studies using indirect methods have proven that global warming, in fact, is causing serious variability in rainfall patterns. Tree-ring analysis for determining rainfall amounts in previous years (hundreds of years back) is one such study proving that rainfall pattern variability has been extensive in recent years.

If this trend continues, environmental managers will be pressed to make new decisions about the management of water and land. They will need to accurately understand the interannual variability of rainfall and a possibility of runs of dry and wet years, which may cause important changes in runoff, sedimentation, soil erosion, and communities of vegetation and animals, and effect the viability of large water-resource developments. Variability in rainfall patterns would also cause mass human migration.

Fiji

THE REPUBLIC OF the Fiji Islands, a part of Oceania, is an archipelago in the South PACIFIC OCEAN, about one-third of the way from NEW ZEALAND to HAWAII. The island group consists of 332 islands (110 inhabited) and has a combined area somewhat smaller than NEW JERSEY. The islands consist mainly of volcanic hills and mountains that are lush in tropical vegetation. The climate is tropical maritime and is characterized by a dominance of warm, moist air masses, high levels of precipitation, cyclonic storms (November through January), and minimal seasonal temperature fluctuation.

Fiji has a high birth rate (23/1000 in 2003), a low death rate (5.7/1000 in 2003), a rapid rate of natural increase (1.7 percent), and a notable out-migration. Population density is moderate, life expectancy is fairly high (68.9 years), and the median age, only 23.7 years, is markedly lower than for North America. The majority ethnic group, Fijian (51 percent), is mainly Melanesian with a strong Polynesian influence. Minority groups include Indians (44 percent), who are mostly Hindu, Europeans, and other Pacific Islanders. Christianity is the primary religion among the Fijians and in the island group as a whole (52 percent), especially Methodism and Catholicism, followed by Hinduism (38 percent) and Islam (8 percent). English, the official language, is accompanied by Fijian and Hindustani. 

Education is free for young people ages 6 to 14, and national literacy is above 90 percent. Fiji has a well-developed economy based largely on sugar exports, tourism, clothing, copra, gold, silver, lumber, and small cottage industries. Being insular, Fiji has a long total coastline and adheres to international guidelines for the division of ocean waters. It claims a 12 nautical mi territorial sea and a 200 nautical mi Exclusive Economic Zone for resource development.

Given its rugged terrain, only 10.9 percent of this island country is arable. Agriculture employs 17 percent of the official workforce and produces a range of commodities from sugar, cassava (tapioca), rice, and coconuts to sweet potatoes, bananas, pigs, and cattle. With this production, Fiji faces serious ecological issues such as deforestation, soil erosion, chemical contamination, and siltation of internal waters.

Fiji received its independence from the United Kingdom on October 10, 1970, amended its constitution in July 1998 to include national open voting, and today has an elected government. Poverty, subsistence living, political polarization between Fijians and Indians, and national fiscal management remain serious challenges. The country’s executive branch consists of a chief of state or president and a head of government or prime minister. The parliament comprises a senate and house of representatives, and the supreme court oversees a legal system borrowed from the British. The country is divided administratively into four divisions, the northern, eastern, western, and central, and one dependency, Rotuma.

Fertile Crescent

THE FERTILE CRESCENT, an area between the Tigris and Euphrates rivers, was called Mesopotamia by the ancient Greeks. This meant “the land between the rivers.” The Fertile Crescent extends from the eastern shore of the MEDITERRANEAN SEA to the PERSIAN GULF and gets its name from its shape. James Breasted, an archeologist from the University of Chicago, first called it the Fertile Crescent.

This region includes present-day ISRAEL, LEBANON, and parts of JORDAN, SYRIA, IRAQ, and southeastern TURKEY. It is believed that civilization first developed in this area, giving rise to the nickname “The Cradle of Civilization.” Scientists think that agriculture began in this fertile valley around 8000 B.C.E. Here, tribes of nomads, who had formerly been hunters and herders, settled. Barley and wild wheat were abundant. Besides the rivers and the fertile land, the area had four of the five most important species of domestic animals: cows, goats, sheep, and pigs. The other species, the horse, lived nearby.

People began to move down from the mountains to the grassy uplands and plains in Mesopotamia. By 7000 B.C.E., farmers were planting wheat and barley and raising domesticated cattle and pigs. The climate of the Fertile Crescent encouraged the evolution of many new species of plants.

Primitive villages stretched across the strip from Assyria to the Euphrates River by 6000 B.C.E. People were learning to cooperate, and social organization grew out of this effort. They learned to irrigate their crops in the drier parts of the Fertile Crescent. By 5000 B.C.E., cities were being constructed in the southern part of the valley. The civilizations of Sumer, Babylon, Assyria, and Persia developed in the Fertile Crescent. 

The Sumerians arrived in the Tigris-Euphrates Valley in about 3500 B.C.E. They came from Central Asia and settled in southern Mesopotamia. They took charge of the land and resources there and developed a complex civilization. The region became known as Sumer. Here, city-states developed, each ruled by a king. The king was in charge of construction of buildings and temples, maintaining irrigation systems, overseeing justice, and making trade and defense policies.

At first, these kings were elected, but later their positions became hereditary. Because of the number of citystates, there was often tension and conflict among them. Conflicts were often over rights to water or land. Sometimes one city-state tried to conquer another. The Sumerians invented the first known system of writing. Called cuneiform, it used a triangular-tipped stylus to make wedge-shaped marks in soft clay. The Sumerians also developed the arts of bleaching and dying fabrics and engraving. They developed surveying equipment and built dams and canals. The Sumerian number system influenced our astronomy and our method of timekeeping, with 60 minutes in an hour and 60 seconds in a minute.

In 2000 B.C.E., the Babylonians took control of the Fertile Crescent. One of their contributions was Hammurabi’s famous code of laws. They had well-developed literature, religion, history, and science. Their number system was more advanced than the one we use today. From the Babylonians, we received modern astronomy and algebra. King Nebuchadnezzar built the Hanging Gardens of Babylon, one of the Seven Wonders of the World. The Babylonian Empire lasted until 538 B.C.E., when the last of the Babylonian rulers surrendered to Cyrus the Great of Persia.

Cyrus was succeeded by his son, Cambyses, who expanded the PERSIAN EMPIRE to include Egypt. After his suicide, Darius I came to power. He instituted a public works program, a postal system, road construction, and a system of minting coins. He also set up a system of weights and measures and built the palace at PERSEPOLIS, the royal center of his empire. It was located in southwestern IRAN.

The Assyrian Empire is hard to pinpoint. The Assyrians, a race of brutal warriors, lived in the northern part of the Fertile Crescent. The first Assyrian Empire lasted only about 50 years before it was assimilated into the Babylonian Empire in 1760 B.C.E. The Assyrians came to power again in the 14th century and managed to extend their borders. From 1070 to 950 B.C.E., little is known about the history of Assyria, but from 950 to 609, when Assyria was overthrown, its history is well-documented.

The biggest contributions of the Assyrians were in the form of techniques of war and specialized equipment used to carry on war. Also, we still use Assyrian words today for many plants and minerals. Contributions by these early civilizations and others have influenced not only the Fertile Crescent area, but the entire world

Federation

GEOGRAPHICALLY, a federation (from the Latin foedus, meaning “league,” “ covenant,” or “ alliance”) is a political system created by the voluntary association of distinct political units and formally established by treaty or compact. It is a system of dual sovereignty. Each unit maintains some form of independent administrative power or local identity and sovereignty. At the federal level, sovereignty normally is confined to group or international relations. Thus we have the united, but separate, states of America or the various independent countries of the EUROPEAN UNION, and the distinct provinces of CANADA and AUSTRALIA as well as 20 or more other countries as current examples. The former Soviet Union claimed to be a federation, but none of its parts had the de facto right of secession or of de facto local independence. Today, it is calculated that there are 21 countries that classify themselves as federal. And there are many economic and military associations that assume the same title, such as the United Nations and the NORTH ATLANTIC TREATY ORGANIZATION (NATO).

Any federation faces a continuing dynamic or struggle between separation of power and a need for unity on specific issues—economic, social or military. Regardless of the forces that created their formation, all federations eventually seek increased centralization and a reduction in the power of their individual units. Some scholars have claimed that only centralized federations last. Scholars consider there to be two basic types of modern federal associations: the original function of an alliance of pre-existing political groups or units and the newer use as a form of decentralization. Decentralizing federations occur when an existing centralized state begins to cede some power to local groups or areas—as with indigenous people or tribal groups.

Generally, federations consist of political entities that share proximity and preferably contiguous borders or territory. Their voluntary association is to increase their power. However, there have been maritime federations whose parts were widely separated, for example, the Greek CITY-STATES. These were more economic in motivation. 

Regardless, the distinguishing characteristic and raison d’etre of any federation is an association of distinct groups that have a strong sense of territorial identity. After the motivation of a need to recognize distinct ethnic and regional politics, it is a recognition of common interests and economies of scale, such as economics (trade), mutual military defense, or need of a unified power-grid or transport system that typically is the reason for maintaining a federation in the 21st century.

Modern examples of federations that reflect this range of motives would include the UNITED STATES, AUSTRALIA, SPAIN, INDIA, ARGENTINA, NATO, the EUROPEAN UNION, MALAYSIA, SWITZERLAND, and many countries in Africa and Central Asia.

Fayum

FAYUM (also spelled “Faiyum” or “Fayyum”), comes from the Coptic Phiom (“sea”), and geographically designates a muhafazah (governorate), formerly a mudiria (province) of Upper EGYPT, an oasis in northcentral Egypt adjacent to the NILE RIVER, with significant paleontological and archaeological interest. Fayum is one of 26 administrative divisions of the Arab Republic of Egypt and is located in a great depression of the Western (Lybian) Desert south-southwest of Cairo. The muhafazah has an area of 707 square mi (1,827 square km) and a population of 1,550,000.

Its capital, located in the southeastern quadrant, also called Fayum, was formerly Madinat-el-Fayum (Medina or City of the Fayyum). The settlement dates to the 12th dynasty (1938–1756 B.C.E.) and achieved considerable importance during the Middle Kingdom. The city was called Shedet in pharaonic times, Crocodilopolis in the Ptolemaic era, and Arsinoe during the Roman period; there were substantial Hellenistic, Roman, Coptic, and Mamluk occupations, and it was a major Coptic Christian center until the Arabs arrived in 640 C.E. The capital is a major Sunni Muslim center with a population of 230,000.

Fayum Oasis, situated 149 ft (45 m) below sea level, is 15 mi (25 km) west of the Nile and separated from the river by a gravel ridge bordered on the west by the Western (or Libyan) Desert. It extends about 50 mi (80 km) east-west and 35 mi (56 km) north-south and is connected with the Nile by the Bahr Yusuf, a canalized river. Irrigation canals were originally dug about 1800 B.C.E.

Paleontologist Elwyn Simons and colleagues conducted research on early anthropoids and other vertebrate fossils from the only continuous sequence of fossiliferous continental middle- to late-Eocene and early-Oligocene deposits on the Afro-Arabian landmass. Important fossils include the genera Propliopithecus, Aegyptopithecus, Parapithecus, Apidium, Oligopithecus, Catopithecus, Proteopithecus, Serapia, Qatrania, and Arsinoea.

Human presence dates to the Paleolithic and Neolithic eras; Fayum A is the oldest Neolithic culture in Egypt. Pyramids were constructed on the ridge funerary complex, built by Amenhotep III at Hawara. Ancient scholars Herodotus, Strabo, and Pliny describe the temple pyramid’s courtyard. The Roman cemetery north of Hawara yielded the famous and unique Fayum Portraits.

Faroe Islands

THE FAROE OR FAEROE Islands (Faerøerne in Danish, Farøyar in Faroese, meaning the “Sheep Islands”) are located at the intersection of the North ATLANTIC OCEAN and the Norwegian Sea, roughly equidistant between NORWAY, SCOTLAND, and ICELAND. Their closest neighbors are the Shetland Islands, 190 mi (305 km) to the southeast. Like the Shetlands, the Faroes were first encountered and settled in the 9th century by Norwegian Vikings, but while the Shetlands were eventually given to Scotland, the Faroes remained part of the Kingdom of Norway, until 1814, when Norway was ceded by DENMARK to SWEDEN. The Faroe Islands (along with ICELAND and GREENLAND) remained a possession of the Danish crown and were given powers of self-government in 1948.

The group consists of 17 inhabited islands, including the main island of Streymoy (or Strømø in Danish) and one uninhabited island and islets. The other main islands are Eysturoy, Sandoy, Suderoy and Vágar. Altogether the coastline stretches 694 mi (1,117 km). The terrain is very rugged, with rocky peaks, and cliffs along most of the coast. Human habitation is thus limited mostly to narrow coastal lowlands. Although the islands are located very far north, the climate is surprisingly mild in the winters from the effects of the upper reaches of the GULF STREAM. Horses and sheep, for example, can winter in the open air. Summers are cool, and year-round skies are usually overcast, with an abundance of fog and wind.

The soil is generally very thin, but some crops can grow, including modest amounts of barley, turnips, and potatoes. There are little to no trees, but abundant turf, which is used for fuel. By far, the biggest industry is fishing and fish processing, with subsidiary industrial activity in shipbuilding and construction. Sheep rearing and dairying supplement the island economy, along with traditional handicrafts and coarse woolen goods. The newest enterprise for the 21st century is the vigorous exploration for potential oil reserves in the seas around the islands. The Faeroe Islands decided not to enter the European Union with Denmark in 1974 and have resisted most development of tourism and potential oil resources. A referendum for independence from Denmark failed in 2001.

Falkland Islands

THE FALKLAND ISLANDS, a British dependency contested by ARGENTINA, which calls them the Islas Malvinas, are located in the South ATLANTIC OCEAN near South America, approximately 300 mi (483 km) east of Argentina. The Falkland Islands consist of two main islands (East and West Falklands), which are divided by the Falkland Sound. There are more than 100 smaller islands that are part of the Falklands. The island of South Georgia, which is southeast of the Falklands, is a territory of the Falkland Islands. The islands have a population of 2,379, with most living near the capital, Stanley. Occupying 4,700 square mi (12,173 square km), the territory’s highest point is Mt. Usborne at 2,312 ft or 705 m.

The Falkland Islands were discovered by the British in 1592 but not claimed by the British until 1690, when a detachment landed for the first time and named it after the first lord of the Admiralty of the time. In the 18th century, French settlers stayed for a short period, and SPAIN also claimed sovereignty. The emerging Argentine state called for the succession of the Spanish, but the British took over the islands in 1833. British settlers since then stayed continuously, although the sheep production made it an economically difficult enterprise in problematic weather conditions (not too far from ANTARCTICA).

The strategic importance of the Falkland Islands is due to their proximity to the southern parts of South America and Antarctica. The islands came twice to global awareness, both in the setting of armed conflict. In 1914, the British navy smashed the East Asian Squadron of the German navy in the Battles of Coronel and the Falklands. In 1982, the Argentine military government occupied the islands but was defeated by the British when Prime Minister Margaret Thatcher decided to resist this military assault. The inhabitants of the Falklands are nearly all of British descent and they never embraced Argentine rule. The British campaign in the Falklands was formidable and outstanding in all its major elements (navy, air force and ground force), as the British won under arctic conditions on islands literally “on the other side of the earth” (from Britain), whereas the Argentine mainland was in close proximity to the battleground. The British victory in the Falklands War led to an overthrow of the military dictatorship because of popular unrest within Argentina, whereby this was a first step for reestablishing democratic regimes in the whole of South America. 

Before 1982, the British government was probably not really interested in keeping the economically deficient islands, but this changed dramatically when the Argentines took it by force. The economy of the Falkland Islands was changed forever after the liberation from Argentine occupation, as the now necessary military presence of British troops needed heavy investment (especially a large airport). Traditionally a coaling and whaling harbor, the Falkland Islands undertook an economic development program for exploiting oil fields within the territorial waters of the islands and for expanding tourism. The role of the Falkland Islands and of South Georgia as a springboard for missions in Antarctica should not be underestimated. The relations with Argentina are still tense, as the Falkland Islanders suspect a new Argentine attempt to take over the islands. Although the British government is unambiguous about not changing the sovereignty of the islands against the will of the inhabitants, the defense of the islands since the 1982 war has cost an enormous amount of British taxpayers’ money.

Facilities Mapping

FACILITIES MAPPING (FM) is the process of digitally identifying and mapping facilities infrastructure with the explicit goal to improve operational management and planning tasks such as dispatching, inventorying, and maintenance. Some examples of facilities include utilities (gas, water, telephone, and electricity), airport siting, and transportation planning. In the past, when a facilities map was needed, a team of surveyors and draftspersons would combine skills to develop such a map. Usually the map was created and updated manually. 

Today, in the competitive business world of facilities service provision companies must continuously find new ways to maintain and deliver efficient services. This is a challenge as the facilities infrastructure is usually dense and covers large geographic areas. Moreover, time is also a key component. The steps for a successful operational strategy is based on collecting and integrating information on organization assets, processes, potential and existing customers, and changing market situations.

The core of the FM system is built around computer- aided drafting and design (CADD), geographical information systems (GIS), and global positioning systems (GPS) technologies. This combination of geospatial technologies has also caused some confusion in drawing disciplinary boundaries of FM. Hence, terms such as AM/FM (automated mapping/facilities management) and network management systems are essentially the same technology. Because of the linear characteristics of the utilities infrastructure, CADD software is generally the choice for digital encoding. 

But there is the tendency now to merge CADD systems with the spatial data management capabilities of GIS in order to develop more integrated databases. The encoded facilities infrastructures are then linked to a database that holds detailed attribute information about each facility. By querying the map on the computer screen, information about each facility and its relationship to other facilities can be obtained for operational planning and management purposes. Updates can be quickly made using a digitizing table, a mouse, and a keyboard. Usually the decisions made using FM are not for analytical purposes but for allocating resources for service dispatching, inventorying, and maintenance. Nevertheless, analytical studies such as network analysis and catchments area analysis are possible with FM systems.

Global positioning systems also play a major role in facilities management. The GPS is a network of 24 orbiting satellites and Earth receiving stations that provide an accurate and unique coordinate position for any point on the Earth’s surface. The network was originally designed as a navigational tool for military applications, but the civilian and research community has quickly realized the value of the technology and adopted it for use in many navigational applications. The satellites transmit signals that anyone can collect with a suitable GPS receiver. For example, with inexpensive GPS receivers, utility service crews can be quickly dispatched to the location of utilities needing repair.

Exotic Rivers

THERE IS A WRITTEN record on the land in the Near East. Here, civilization arose out of the mysteries of the stone age and gave rise to cultures that moved eastward to CHINA and westward through Europe and across the ATLANTIC OCEAN to the Americas. Achievements of ancient origin serve as constant reminders of our debt to the Sumerian peoples of Mesopotamia whenever we use the wheel, look at the clock or our watches to tell time divided into units of 60, or view our calendars as a revision of the method the ancient Egyptians used in dividing the year. Our inheritance in both experience and knowledge from the past is far more than we know or realize.

No one knows exactly when humans began the transition from hunting and gathering to sedentary living. But we do find a very close relationship between the organization of humans in settled areas and the rise of agriculture and the domestication of crops. Agriculture had its most referenced beginnings at least 7,000 years ago in two great centers: one in the fertile alluvial plains of a land called Mesopotamia and the other along the lower reaches of the Valley of the Nile. We shall leave the interesting question of the precise area in which agriculture originated to the archaeologists. It is enough for us to know that it was in these alluvial plains in an arid climate that the first tillers of soil began to grow food crops using IRRIGATION in quantities that exceeded their own needs.

Where agriculture was practiced under especially favorable conditions, it was even possible to produce more food than the local inhabitants actually needed at any given time. The significance of being able to produce surplus food can scarcely be overemphasized, for by releasing some workers from the day-to-day chores of tilling the fields, it permitted a diversification and specialization of labor that had never before been possible.

Of course, the basic need behind all of this is water, for without water there is little evidence of life let alone society or civilization. Even today, we find more than 90 percent of the world's population living within 62 mi (100 km) of the coast or a major navigable river. It should also be pointed out that in the wake of surplus food production and the concomitant necessity for food storage, other modifications in the material culture of the peoples were almost inevitable hallmarks of such an advance. Vessels for storage, such as baskets and pottery, now became part of the inventory of the average household. And the latter, in particular because of its relative imperishability, has become a favored diagnostic tool of the archaeologist in tracing the economic evolution of a culture.

Although examples of preagricultural ceramics do exist, the more usual case is that they are evidence of a settled, farming society of greater complexity and sophistication. It was this organization of community (or place) around a multitude of functions that led Greek scholars to later conclude that cities grew up as a response to human NEEDS AND WANTS.

RIVER CIVILIZATIONS

Historically, the archaeological evidence suggests that the first great civilizations were all river civilizations. Even more interesting is the fact that in each of these early cases, the lands on which these early civilizations took form were also very dry, DESERT or semidesert environments.

Desert regions can be found on all continents and they occur in two zones, one on either side of the equator. One zone is found between 15 degrees N and 30 degrees N latitude and the other between 15 degrees S and 30 degrees S latitude. Most deserts are found on the western side of continents and extend inland. Only the Sahara Desert extends from one side of a continent to the other.

Though little rain falls in deserts, deserts receive runoff from ephemeral, or short-lived, streams fed by rain and snow from adjacent highlands. These streams fill the channel with a slurry of mud and commonly transport considerable quantities of sediment for a day or two. Although most deserts are in basins with closed, or interior, drainage, rivers that derive their water from outside the desert cross a few deserts. These rivers receive a lot of rainfall (or snowfall) in the areas where they arise, that is, in the area known as their headwaters. This large supply of water allows them to flow across the desert even though a lot of water is lost through evaporation into the atmosphere or through seepage beneath the desert surface. These rivers are called exotic rivers because the water they carry comes from outside the desert region they pass through. Such rivers infiltrate soils and evaporate large amounts of water on their journeys through the deserts, but their volumes are such that they maintain

their continuity. 

These older, specially favored areas of human habitation and food production have typically been found in the so-called exotic river valleys of the Near East, such as the Tigris and Euphrates in Mesopotamia (present day IRAQ), as early as 4500 B.C.E.; in the Nile Valley of EGYPT by 4000 B.C.E.; the Indus Valley of PAKISTAN by 3500 B.C.E.; the valleys of the AMU DARYA and Syr Darya in Central Asia by 3000 B.C.E.; and the HUANG (Yellow) and Wei river valleys of North CHINA by 2500 B.C.E. In every instance there was a desert climate with cloudless skies, lots of daily sunshine, little if any frost, little or no vegetation cover to clear, and rich alluvial soils coincided with a continuous supply of water from the adjacent river. Indeed, each of these exotic river valleys was either the cradle of a civilization in its own right or, at least, the beneficiary of a diffusion, which first began in Mesopotamia and was later emulated elsewhere under remarkably similar environmental conditions.

These so-called exotic rivers cross all of the large deserts of the world, except those of AUSTRALIA. Also, desert soils are usually quite productive when supplied with water. The most widely cultivated areas are where there are water-transported soils in the form of FLOODPLAINS and ALLUVIAL FANS. 

There is good evidence that in the New World the model of “hydraulic” civilizations based on exotic rivers as described above may have been first replicated in the Atacama Desert along the west coast of PERU where about 40 short exotic rivers cut their way from the ANDES to the PACIFIC OCEAN. The other New World area where a hydraulic culture occurred was in the Colorado Plateau region of the southwestern part of the UNITED STATES (the southwest Anasazi culture), where the Colorado River cuts its way from the ROCKY MOUNTAINS across the plateau and into the Sonoran and the Mojave Desert before emptying into the Gulf of California. There are a number of examples of exotic rivers where civilization did not seem to take hold. These include the Snake River in IDAHO and parts of the Columbia River which cuts through desert landscapes of WASHINGTON and OREGON. There are no exotic rivers in Europe or Australia.

Mount Everest

A PEAK ON THE CREST of the Great Himalayan range in Asia, Everest is the highest point on the Earth. It lies in the Central HIMALAYAS on the border between NEPAL and CHINA (Tibet). Three barren ridges, the southeast, northeast and west culminate in two summits at Everest (29,028 ft or 8,848 m) and South Peak (28,700 ft or 8,748 m). The mountain can be seen directly from its northeastern side where it rises about 12,000 ft (3600 m) above the plateau of Tibet. It claims an incredible view from the top. The formerly accepted elevation of 29,028 ft (8,848 m) established in the early 1950s was recalculated in the late 1990s as 29,035 ft (8,850 m). Its identity as the highest point on the Earth’s surface was not recognized until 1852, when the Survey of India, a government organization established that fact. In 1865, the mountain, previously referred to as Mountain Monarch or Peak XV, was renamed for Sir George Everest, a Welshman, who was the surveyor general of India from 1830 to 1843.

The summit itself consists of rock-hard snow; surrounded by a layer of snow that fluctuates annually by some 5 to 7 ft (1.5 to 2 m). It is highest in September and lowest in May, after depletion by the strong northwesterly winter winds. Though the exact thickness of snow atop Mount Everest remains a mystery for scientists around the world, the measure taken by an Italian mountaineering team was more than 8 ft (2.5 m). Individual glaciers around Mount Everest are the Kangshung Glacier (east), Rongbuk (north and northwest), the Pumori (northwest), the Khumbu (west and south) and an enclosed valley of ice between Everest and the Lhotse-Nuptse ridge. 

The mountain’s drainage pattern radiates to the south, west, north, and east. The glaciers melt into rivers flowing towards Tibet and Nepal. Precipitation falls as snow during the summer monsoons (May to September). Lack of oxygen, powerful winds, and extremely cold temperatures preclude the development of any plant or animal life on the upper slopes. At the summit of Mt. Everest, atmospheric pressure is only 30 percent that of sea level, so the climbers take in only 30 percent as much oxygen (and thus need to carry oxygen tanks). There are no permanent settlements here because no one can adjust yearround to such high altitudes.

Attempts to climb Everest began with the opening of the Tibetan route in 1920. Everest was finally surmounted in 1953 as a result of efforts by an expedition sponsored by the Royal Geographical Society and the joint Himalayan Committee of the Alpine Club. On May 29, 1953, Edmund Hillary and Tenzing Norgay became the first to reach the top of the world’s highest peak. Since then, 1,200 men and women from 63 nations have reached the summit. Nearly 200 others have perished in the attempt. Japanese woman climber Junko Tabei in 1975 became the first woman to summit Everest. 

The South Col route to Everest is the most popular and used by more climbers than any other path. The north ridge route begins in Tibet. At the foot of Mount Everest, Rongpu Gompa is the highest monastery in the world. The local people revere the mountain. Its Nepali name (Sagar matha) and Tibetan name (Qomolangma) mean “Goddess mother of the world.” The Sherpas, an ethnic group of the Khumbu valley beneath Everest, urge their clients to ask the mountain deity’s blessings with offerings of rice and incense at base camp. Buddhist legend holds that Everest is home to a goddess bearing a bowl of food and a mongoose spitting jewels. Everest has indeed brought prosperity to the region.

The first ascent of Mount Everest sparked a tourism boom that draws more than 20,000 visitors each year to hike amidst the planet’s tallest peak. The 50th anniversary of the first ascent of Everest was celebrated in May 2003. Efforts at cleaning up the Everest slopes started in 1994, and more than 20,000 pounds of garbage have been hauled off the peak. Sherpas are paid to bring down used oxygen bottles and other trash.

A Chinese survey has revealed that the world’s highest peak is gradually losing its height because of global warming and the shrinking of glaciers in the Himalayan region. According to a scientific survey report released at a recent international symposium held in Lhasa, Tibet, the mountaintop declined by 4.2 ft (1.3 m) in the 33 years ending in 1999. Global warming accelerates the process of conversion from snow to ice.

Ethiopian Highlands

ETHIOPIA IS A LANDLOCKED nation located in northeastern Africa in an area known as the HORN OF AFRICA. While containing large stretches of plains in the east and south, the country is dominated by highlands, which rise to well over 3,000 ft (1,300 m), and the Great Rift Valley, which is several hundred meters below sea level. Elevated plateaus compose much of the geography in northeastern Africa, an area close to the RED SEA, which encompasses both ERITREA and ETHIOPIA. Likewise, the Great Rift, formed 50 million years ago by volcanic activity, also extends across most of eastern Africa and bisects Ethiopia’s central mountainous plateau from roughly the southwest to the northeast, creating two highland areas. The largest, the western side, is known as the Ethiopian Plateau and is the higher of the two, with the tallest peak, Ras Dashan at 15,158 ft (4,620 m). Located in the Simen Mountains, the peak is located southwest to two similar, though slightly less imposing mountains. Aside from being among Africa’s highest mountains, the area is also the source of the Blue Nile, Lake Tana. 

Land on the eastern plateau slopes in a generally westerly direction and provides much of Sudan, and ultimately the NILE, with water. The smaller, eastern plateau extends toward the Gulf of Aden, on the INDIAN OCEAN, and divides the lowlands to the east, near Somaliland, from the Danakil Desert by the Eritrean border. The verticals of both plateaus are very impressive. In the center, the Great Rift rises at almost a vertical to both heights. The eastern spur, however, is generally more gradual than the Ethiopian plateau in the west and slopes into the surrounding desert. Water erosion has created impressive cuts throughout the highland; vertical drops of many thousands of feet are common. In addition, the same erosion has created smaller plateaus, knows as ambas, which are the sites of many of the nation’s important battles and monasteries. The highlands obviously have influenced Ethiopia’s climate, demographics, and history. Despite being so close to the equator, Ethiopia has a quite moderate climate largely because of its heights. Outside of the Danakil depression, the Great Rift Valley floor, and the eastern plains, which are primarily desert, Ethiopia’s climate varies from alpine, in the higher mountains, to moderate. The capital city, Addis Ababa is located at 8,000 ft (2,450 m), with average yearly temperatures of 68 degrees F (20 degrees C).

Winter, which can be very brutal in some higher areas, lasts from October to February. Spring is generally drier, though some rains do occur. The heaviest rains fall in the summer months, from June to mid-September, and taper off in the autumn months. Given the relative heights and sloping of the highlands, and the amount of water it receives, there are numerous lakes and rivers. Most of the forests are in the southwest, while the plateau highlands contain scattered copses and GRASSLANDS. Fauna in the highlands are mainly domestic animals, such as cattle, which graze on the grasslands, and birds, large cats, hyenas, and wolves.

Early human habitation started out in the Rift Valley, with the oldest human ancestor being found there in 1974. Over time, habitation expanded to the highlands, providing people with rich soil and grazing space for their animals. One of the first Ethiopian civilizations arose in the northwest plateau, at Aksum. Over time, the highlands, including portions of northern and northwestern Eritrea, were incorporated into various Ethiopian Christian kingdoms, often at war with the Muslims in the eastern lowlands. The highlands protected Ethiopia from many foreign invasions, particularly from the Italian colony of Eritrea in 1896. At the Battle of Adowa, fought in the highlands just south of the Eritrean border, the Imperial Army of Ethiopia destroyed an Italian-led Eritrea force. The highlands, however, were unable to completely protect against the Italian invasion of 1935.

Ethiopia

ETHIOPIA IS LOCATED in northeastern Africa, an area rich in geography, climate, and history. The Great Rift Valley, which extends across most of east Africa, bisects Ethiopia’s central mountainous plateau, providing the country with highlands, mountains, plains, and climatic diversity. The heaviest rains occur in the summer months with a lighter rainfall in the spring, when the monsoons arrive from the INDIAN OCEAN. Rains in the south and southwest of the country are nearly continuous over the year, moderating temperatures in the highlands, where most of the population lives, and leaving the eastern plains drier and hotter. The capital, Addis Ababa, is located at 8,000 ft (2,450 m), with average yearly temperatures of 68 degrees F (17 degrees C).

The nation’s major river, the Blue Nile, is fed by runoff from the western portion of the plateau and flows toward the NILE and SUDAN to the west. Ethiopia’s forests and wooded areas are concentrated in the southwest, and are centers of coffee production, while cattle are grazed on the grasslands. Despite its climate, Ethiopia faces severe deforestation and DESERTIFICATION problems, mainly caused by the civil war, drought, and famines. Ethiopia is rich in human history. The earliest known hominid, “Lucy,” was unearthed in 1974 near Addis Ababa and was dated to 3.5 million years ago. 

Archaeological research indicates continuous human habitation for the past 2 million years. Neolithic civilization entered Ethiopia from EGYPT and the RED SEA, indicating a trading network that connected the area to the Mediterranean and Arabia. Traditional Ethiopian history started when the Queen of Sheba, purportedly from Ethiopia, visited King Solomon in the 10th century B.C.E. Historically, however, Ethiopian history originated in the second millennium B.C.E. under the influence of the Egyptians and later Greeks. An independent Ethiopian civilization emerged in the 1st century C.E. in Aksum and its seaport, Adulis. The Aksumite kingdom traded with the peoples of the Red Sea and interior of Africa.

In the 4th century C.E., Greek missionaries introduced Christianity from Alexandria, EGYPT. In 451, exiled Greek and Syrian monks established Monophysite Christian communities throughout the kingdom furthering the influence of the Egyptian Coptic rather than the Roman Catholic Church. In 525, the Aksumite king, responding to a request from Emperor Justinian I to aid persecuted Yemeni Christians, invaded and occupied the southern portion of the Arabian Peninsula until the Aksymites were expelled by the Muslims at the end of the century. The Aksumites, however, used their expanded holdings to trade with INDIA and maintain communication with the Byzantines.

This period of expansion was not long lasting because by the middle of the 7th century, Islamic invaders from Arabia conquered Egypt, isolating the Auxites from the broader Christian world. Isolation meant a gradual political decline over the next 300 years, with central authority collapsing in the 10th century. Ethiopia entered a period of warring chieftains and provincialism. Finally, in the late 13th century, the Solomonic dynasty, so named after its lineage to King Solomon and the Queen of Sheba, reestablished central authority with the new dynasts claiming the title of Negus Negusti, king-of-kings. The kingdom consolidated political and military power and expanded against a series of smaller Muslim principalities to the south. During this period of renewed expansion, Europeans reestablished contact with the Christian Ethiopians.

In 1490, Portuguese explorers searching for the legendary Christian kingdom of Prestor John arrived and subsequently aided the Ethiopians against the Muslims. Relations with the Europeans soured when the Portuguese tried to pressure the Ethiopians into accepting Roman Catholicism. The Ethiopians then expelled the Europeans and enacted a strict isolationist policy, which lasted until European imperialism encroached into Africa during the 19th century.

In 1869, Italian imperialists purchased the nearby Red Sea port of Assab from the Egyptians. In 1882,

Italy acquired the surrounding territory and merged their holdings into a single colony. Not satisfied, the Italians expanded northward along the coast into territory claimed by the Ethiopian kingdom. To avoid potential conflict, the Italians and Ethiopians agreed in 1889 that Italy could expand into limited areas of northern Ethiopia. Tensions mounted, however, after Italy formed the colony of ERITREA and became involved in a dynastic struggle in Ethiopia. The tensions touched off a native uprising in Eritrea, leading the Italians to invade Ethiopia hoping to end any aid given the native Eritreans by Ethiopia.

The Ethiopians soundly defeated the invaders in 1896 at the Battle of Adowa, thereby ensuring the empire’s continued independence from European imperialism until well into the 20th century. The Italians vowed revenge, and in 1935 the Italian fascist regime invaded and conquered Ethiopia. Emperor Haile Selassie fled to Great Britain and remained in exile until the Allies liberated Ethiopia and Eritrea in 1941. Selassie returned to power and in 1952 ruled over a federal system of Ethiopia and Eritrea until the early 1960s, when he annexed Eritrea.

In 1974, the Derg, a military council, overthrew the emperor and eventually imposed a totalitarian regime with Soviet aid. In 1991, the rebel Ethiopian People’s Revolutionary Democrat Front, a coalition of the various domestic opposition groups, overthrew the government and promulgated a new constitution. Under pressure from ethnic minorities for more local government, the new government subdivided the nation into nine provinces with a legislative assembly.

Estonia

FOR CENTURIES DOMINATED by its larger and stronger neighbors, since independence from the former Soviet Union in 1991, the small country of Estonia has shown itself to be the economic tiger of the former communist countries of Eastern Europe. The smallest of the three Baltic states, Estonia was the first to reintroduce its own currency and has managed to reduce inflation from 1,000 percent in 1992 to 2.8 percent in 1999 and unemployment to a mere 3.3 percent, well below the EUROPEAN UNION (EU) average. Having joined the NORTH ATLANTIC TREATY ORGANIZATION (NATO) in 2002, Estonians embarked on a new course, firmly directed toward the West, with membership in the EU dating from May 1, 2004.

Estonia is closely tied to the Baltic region, with a long coastline (2,618 mi or 3,794 km), including its northern coast on the Gulf of Finland and over 1,500 islands in the Baltic Sea. The largest of these are Saaremaa and Hiiumaa. Its neighbors include RUSSIA to the east, and LATVIA to the south, with FINLAND a short distance across the gulf (about 53 mi or 85 km) at its closest.

Historically, the region was connected to other Baltic powers through sea commerce and the economic expansion of German merchants during the Middle Ages. Estonia’s towns were essentially German for most of their history as members of the vast Hanseatic League, including its main city of Tallinn, formerly known as Reval. The area formed a province in the changing empires of the region, either Danish, German or Swedish, and finally Russian from 1721. The Estonian people themselves, sharing ethnic and linguistic affinity with the Finns (and, more distantly, Hungarians), generally populated the countryside and served as the agricultural labor force supplying the industry and trade of the Germanic towns. 

In the 19th century, however, Estonian nationalism stirred and began to clamor for an independent Estonia for Estonians. Yet as late as 1914, the so-called Baltic Barons, German noble landowners, still owned 90 percent of the large agriculture estates (60 percent of the total land) and dominated the cities as they had done since the Middle Ages.

With GERMANY’s defeat in 1918, Estonia declared itself independent, but this was short-lived, and the country was occupied by the Soviet Union in 1940, and formally declared a Soviet socialist republic. The terrain is mostly flat and marshy in the north and west, becoming more hilly in the south and east. Bogs and wooded swamps cover a fifth of the country, and there are over 1,500 lakes. The largest of these lakes form part of the border with Russia, Lake Peipus and Lake Pskov. These lakes are connected by a channel, and flow out toward the Gulf of Finland through the Narva River. Vörts-Järv is a large inland lake whose waters flow eastward into Lake Peipus, passing by Estonia’s second-largest city, Tartu.

ESTONIAN INDUSTRY

The Narva corridor is also the center of Estonia’s heavy industry, highly developed under the Soviet regime, with more investment per capita from Moscow than any other part of the Soviet Union. Estonian industry was geared to production of oil—from one of the world’s largest deposits of combustible shale—and also military supplies. Leningrad, roughly 245 mi (395 km) away, became dependent on Estonia for gas and oil, but also relied on Estonia’s fertile soils and dairy farms for its food needs, much as the city had done (as St. Petersburg) since its founding in the early 18th century.

Estonians remain wary of the large Russian population still living in Narva, while it converts the remains of the Soviet military industry to more useful products. Estonia has a very low population density, allowing much of the land to remain cultivated in small farms or left wooded for the second-largest economic activity, timber, paper, and furniture. Approximately one-third of the population lives in Tallinn. The fastest growth is occurring in service industries, such as tourism, trade and banking, and Estonia is becoming famous as a leader in e-government.

Esker

AN ESKER IS A LONG, narrow, often snakelike ridge of sand and gravel deposited on top of the ground where a glacier has retreated. Eskers often follow valleys and lowlands, although some can go uphill. Most eskers are a single ridge, but there are also braided ridges, which are similar in shape to river tributaries. The esker got its name from an Irish Gaelic word, eiscir, which means “ridge of gravel.” If they are viewed from the air, eskers stand out from the rest of the terrain. They often look like large railroad embankments. Eskers are made up of all sizes of fluvial materials, from fine grains of sand to boulders. Most material, though, is the size of gravel. The finer sediments are often found near the top of the esker, while the large boulders will be much deeper. Eskers usually have steep sides of 25–30 degrees.

Most eskers formed during the time when glaciers were melting and retreating. A tunnel formed in the ice within the glacier, and meltwater began to run through the tunnel like an underground river. The water carried sediment with it. As it slowed down in certain places, some of the sediment was dropped and began to fill up the tunnel. As the tunnel filled up, the pressure of the water eroded the ice above it to make room for the water to continue flowing. Therefore, the whole tunnel seldom filled with sediment. When the glacier melted, the sediment in the tunnel was lowered to the ground.

It followed the route of the underground river, which was usually perpendicular to the face of the glacier. Most eskers formed in enclosed tunnels through which water flowed, but a few formed in ice-walled trenches that were open to the sky. Only in the channels that were closed by ceilings was the water able to flow uphill. This worked like water under pressure in the pipes of a water system. In the ice channels on top of the glacier, the sediment was let down to ground level as the glacier melted. Eskers range from a few meters high to over 250 ft (200 m) high. However, most are 100 ft (30 m) or less. Some are a few miles long, and others can be as long as 311 mi (500 km). Scientists believe that a very long esker probably did not form as one event but is made up of many individual eskers formed together during the retreat of the ice sheet.

Most eskers consist of a long, continuous ridge, but some have breaks in them. This happened because in some places, if the water was flowing more quickly, no sediment was deposited. Sediment was laid down when the speed of the water slowed down. Some eskers are known as “beaded eskers.” They have a regular pattern of narrowing and widening out. This is believed to have been due to the fact that more sediment was deposited in summer than in winter.

Through the years, eskers have served several purposes. Since they are raised above the surrounding terrain and are often more firm than the land around them, they have been used as road beds. In IRELAND, the Eiscir Riada is still used as the base of Highway N4/NM6 from Dublin to Galway. The land around it is boggy, so the esker provides a firm foundation for the road. In the wilderness, wildlife typically use eskers as travel routes. Eskers have also been used as graveyards and golf courses. Recently, prospectors have used eskers to predict where diamonds will occur. Bush pilots flying over the Canadian wilderness often use eskers to guide them. The largest eskers in the world are found in the Canadian provinces of Nunavut, Manitoba, Quebec, and Labrador.

Many eskers have entirely disappeared, though, because the gravel that made up the esker has been excavated and used to build roads. Where a gravel pit has been dug in an esker, scientists are able to study the internal structure of the esker.

Escarpment

IN GEOLOGY, an escarpment is a steep edge of a ridge or cliff, characterized by an abrupt transition in altitude between two relatively level but differently composed series of sedimentary rocks, differing in age and composition. Escarpments, also known informally as “scarps,” are usually representative of the line of erosion of newer rock over the older rock and can exist both on dry land and below water. Escarpments are types of precipitous cliffs that can be formed by faulting of land or erosion by the elements of weather such as wind, water, or ice and are likely to be formed of limestone, sandstone, chalk, granite, and basalt.

Studies performed on various escarpment samples show that, in many cases, they were formed as a result of a process of erosion dating back over millions of years. Depending on circumstances, most escarpments have developed by erosion of ice dating back to the Ice Age or of water from the melting of glaciers and flows of streams. In some cases, more than one escarpment can exist in the same place. In other cases, escarpments are eroded and further formed from the sliding movement of sediment under water, such as with oceanic water movement and submarine landslides.

Escarpments on land can serve as homes to a wide variety of trees, plants, and other organisms that have been forced there or that simply prefer to live on rocky areas. Dense colonies of organisms, algae, and fungi, previously thought to be found only in distant ecotones such as Antarctica, have been found to exist in many dry land escarpments. Escarpment formations have also been found on other planets, such as in the mountains of Jupiter’s moon, Io. Geologists think escarpments have been formed from a combination of unstable land and volcanic stress.

Little by little, escarpments and cliffs are undergoing changes and erosions of a different kind as an everincreasing number of people discover the wonders of the outdoors through rock climbing. Often, as the climbers scale along the rock surfaces, they pull out plants and brush in order to make the climbing surfaces safer and easier to navigate. The removal of the fauna and flora, as well as the steady rate of climbers passing through, is progressively changing the face of many escarpments and natural landscapes around the world.

Erosion

EROSION HAS MADE huge changes in the surface of the Earth and is still doing so today. Erosion is the removal of materials from the Earth’s surface by a variety of processes. The material is eventually deposited elsewhere, often far from where it started. Most erosion is caused by the action of wind, water, or ice. Water causes the most erosion. Weathering is the breaking down of rock into smaller particles. Erosion differs from weathering in that erosion involves something moving—wind, rain, or a glacier.

During the natural process of erosion, the landscape is changed over thousands or millions of years. Mountains are worn down, valleys are filled in, and rivers change their courses. These changes are gradual, but many of the practices of man speed up the process of erosion and cause serious problems around the world. Construction is one of the biggest culprits. Topsoil, minerals, and nutrients are lost from every construction site. About 80 percent of the erosion in FLORIDA is due to manmade activities. Cutting the forests and plowing the land has also contributed to erosion of the land.

Human activities cause topsoil to be lost, along with the minerals and nutrients it contains. This affects agriculture. Erosion causes ugly gullies in the landscape. Materials from water erosion can clog culverts and streams. Recreational areas and residential areas are damaged by erosion. Wildlife may be destroyed and its environment altered to the point that it can no longer support wildlife.

Water erosion includes stream erosion, beach erosion, and erosion by flooding. Stream erosion is most common. Streams carry sediment from one place to another. The amount of sediment carried and the amount dropped depend on the speed of the water. Water speed is affected by many factors, including the steepness of the slope and the shape of the channel through which the stream flows. The faster the water moves, the more material it can carry, and the larger particles it can move. When water goes around a bend, sediment is removed from the outer part of the bend and swept downstream. Water flows more slowly on the inside of the curve, so sediment accumulates here as it is dropped by the slowing water. Valleys eroded by streams are V-shaped, as opposed to the U-shaped valleys eroded by glaciers.

Heavy rains in spring can increase the velocity of a stream and cause more erosion to take place. Sandy ground erodes more easily than rocky ground. At its most extreme, stream erosion has created wonders like the GRAND CANYON. This vast canyon was eroded by the Colorado River, although some scientists now believe other rivers helped cut the canyon. The canyon, which is 227 mi (446 km) long, averages 4,000 ft (1,219 m) deep. Its deepest point is 6,000 ft (1,829 m) and the widest point spans 15 mi (24 km) This erosion took place over a period of millions of years. Beach erosion occurs along ocean shores and can be caused by natural phenomena or by humans. Natural phenomena that can cause beach erosion include currents, storms, earthquakes, winds, waves, and tides. The gradual movement of the Earth’s tectonic plates can also cause beach erosion.

Unlike stream erosion, which takes place over a period of many years, beach erosion can be immediate. This is especially true in the case of a storm. However, even in calm weather, sand may be pulled out into deeper water, causing it to be lost from the beach. Loss of sand is significant, since the beach both protects the land behind it and provides recreation areas and habitat for wildlife. The beach absorbs energy from the sea, and the wider the beach is, the more energy it will absorb before the waves reach landward developments.So when sand is washed away, making the beaches recede, more damage is likely to be done to houses and developments.

Global warming also has its effect on beach erosion. It causes the sea to warm up and the polar ice caps to melt. This raises the level of the oceans, causing more erosion.

Eritrea

ERITREA IS LOCATED in northeastern Africa, an area known as the HORN OF AFRICA, where the RED SEA empties into the INDIAN OCEAN. Eritrea is bordered to the south by ETHIOPIA, which until 1993 incorporated Eritrea within an autonomous zone, to the west by SUDAN, and to the southeast by DJIBOUTI. Among these neighbors, Eritrea shares much geography and climate, particularly with Ethiopia.

In particular, the Red Sea and Indian Ocean determine much of the country’s weather. Likewise, a large central highland plateau extends northward from Ethiopia and helps to moderate Eritrea’s temperatures. These highlands are generally wetter and cooler than the coastal lowlands to the east or the plains to the southwest. The country’s major population settlements are concentrated in these temperate highlands. Eritrea has two rainy seasons, with the first and heavier occurring during the summer and the lighter one in the spring.

Eritrea was dominated by other larger powers, falling under the sway of first the Egyptians, Ethiopians, and finally the Italians. In 1869, imperialists purchased the southern port of Assab and quickly expanded their holdings with further purchases northward to Massawa. Italian colonialists confronted the Ethiopians, which after 1889 led to the Italians expanding into northwestern Ethiopia. 

Subsequently, the Italians launched an invasion of Ethiopia from their colony Eritrea but were decisively defeated at the Battle of Adowa in 1896. This defeat led the Italians to concentrate on developing Eritrea for its economic and strategic importance. In 1935, the Italians attacked and conquered Ethiopia, merging the two colonies until the British defeated the Italians in 1941. At the end of the war, the United Nations assigned Eritrea to Ethiopia, making Eritrea an autonomous region within Ethiopia in 1952. Relations frayed as the Eritreans demanded their independence. The Ethiopians dissolved the autonomous zone and annexed Eritrea in 1962, sparking 30 years of Eritrean armed struggle.

In the late 1970s and through the 1980s, the situation dramatically improved for Eritrea. First, domestic opposition groups in Ethiopia launched an insurgency against the Ethiopian regime. Second, the Eritrean People’s Liberation Front made significant headway on the battlefield, driving the Ethiopian military from most of Eritrea by 1988. Shortly thereafter, the Soviet Union ceased its military aid to the regime, denying the military equipment necessary to pacify Eritrea and fight the Ethiopian insurgents. In 1991 the regime crumbled, ending the hostilities and granting Eritrea its independence. Tensions remained, however, and in 1998 the two states clashed again in a brutal border dispute that ended with a peace treaty in 2000.

Lake Erie

LAKE ERIE, bordered by the province of Ontario in CANADA to the north, NEW YORK to the east, PENNSYLVANIA and OHIO to the south, and MICHIGAN to the west, is the shallowest of the Great Lakes at only 62 ft (18.9 m) and it remains the smallest in volume. Lake Erie is 241 mi wide (380 km), and 57 mi (91 km) from north to south and has 871 mi (1,401 km) of shoreline. Because of its shallowness, Lake Erie is the warmest of the Great Lakes in the summer, meaning it is the most biologically productive, and during the winter, it is the only lake out of the Great Lakes to freeze. Lake Erie is one of the five large freshwater lakes in North America.

The other lakes surrounding Lake Erie are Lake SUPERIOR, Lake MICHIGAN, Lake HURON, and Lake ONTARIO. Eighty percent of the lake’s water flows in through the Detroit River, carrying water from lakes Superior, Huron, and Michigan. Lake Erie is the most heavily populated freshwater BASIN in the world. There are 17 metropolitan areas within the basin.

Ecological problems have threatened this site more so than any other of the Great Lakes. Historically, this lake was used moderately by Native Americans for food and water. Later, when the Europeans arrived, they found a somewhat stable ecosystem that remained so mainly because of the Europeans’ interest in animal furs. However, that all changed when the large influx of immigrants arrived and began to utilize the land for agriculture and the water for fisheries. Industrialization and urbanization soon followed slowly lowering the quality of the water. Some of the many prominent problems was bacterial contamination, putrescence, and floating debris in the water. This undoubtedly led to diseases such as typhoid fever being contracted by people exposed to the water.

In the 1950s, Lake Erie also was the first of the Great Lakes to display lake-wide eutrophic imbalance. Eutrophic imbalance refers to the imbalance of minerals and nutrients that promote proliferation of plant life in lakes and ponds. This was present because of the high levels of phosphorus output by factories in the very highly populated Lake Erie basin, and it had dire consequences on the lake’s ecosystem. Depleted oxygen levels were found along with excessive algal growth and the disappearance of entire families of fish.

The 1960s brought growing public concern regarding the state of the lake’s water. Lake Erie was actually called the dead lake by the press. It evolved from a stable ecosystem to one very much affected by artificial fertilizers used by the surrounding farmers, waste from the surrounding communities, and factory waste. Floating waste, putrescence, and bacterial contamination were all of great concern to both the U.S. and Canadian governments. This concern brought much needed government measures to stabilize the lake’s ecosystem. Greater investment in pollution research by the U.S. and Canadian governments and efforts to regulate the toxicity and level of waste being released by the factories began in earnest.

In 1987, the United States and Canadian governments signed the Great Lakes Water Quality Agreement (GLWQA) to develop a management plan for the Great Lakes. More specifically, under the GLWQA, they created the Lake Erie Lake-Wide Management Plan (LaMP), which included efforts from local, municipal, state and federal offices in the four surrounding states of Michigan, Pennsylvania, New York, and Ohio and the province of Ontario. The four subcommittees within the LaMP are; Beneficial Use Impairments, Sources and Loadings, Ecosystem Objectives, and Public Involvement.

Thanks to the efforts made by both the American and Canadian governments, Lake Erie’s ecosystem has returned to a more stable state with lower phosphorus output levels, and it appears as if the eutrophic imbalance is being adequately dealt with by the governments as some species of fish have returned to the lake.

Erg

THE TERM erg is the Bedouin name for a very large body of sand dominated by sand dunes. Bedouins are an African tribe of nomadic herders living in the northern SAHARA DESERT. Two equivalent English-language terms are sand sea and dune field. Transverse dunes typically are part of ergs, or sand seas. As sand is seemingly everywhere, the dunes appear as waves in a sea of sand. Hollywood made this sandy landscape famous in classic movies such as Lawrence of Arabia, in which sword-wielding Arab horsemen galloped across seemingly endless seas of velvet-soft dunes. Contrary to popular belief, ergs are usually not continuous deposits of fully formed dunes; small inter-dune exposures of underlying bedrock, soil cover, or deposits of ephemeral lakes and streams are common.

Ergs require huge supplies of sand. The sand of an erg is usually from nearby dry lakebeds, ALLUVIAL FANS, smaller dune fields, remnants of earlier sand seas, or coastal dunes. The Namib erg, which stretches along the southern coast of Africa, receives its sand from nearby coastal dunes. Some ergs are surprisingly far from their sand supplies. This fact is especially true in the Sahara Desert of northern Africa, where sand may flow thousands of kilometers before entering a sand sea. 

Wind patterns will also affect sand supply. For instance, dunes in southern Africa and AUSTRALIA tend to be linear and form whorls (or wheelrounds) that stretch outward from their central areas. These whorls indicate an counterclockwise movement of sand in response to continental anticyclones that dominate the two regions. Topography also affects sand supply. For instance, several ALGERIA sand seas occur close to upland areas, where the uplands extend across the regional trend of sand drift. Some of the more striking sand seas occupy topographic basins. The Simpson in Australia and the Taklimakan in CHINA are examples.

Ergs or sand seas are impressive for their areal coverage. There are major ergs in northern Africa, southern Africa, the Arabian Peninsula, Central Asia, PAKISTAN, and China. The largest contiguous erg covers 1 million square mi (2.5 million square km) in southern Africa’s KALAHARI DESERT. Natural vegetation has stabilized most of this sand sea. The largest active sand sea is RUB AL KHALI in SAUDI ARABIA, which stretches across 220,000 square mi (560,000 square km). The region with the greatest number of ergs is northern Africa’s Sahara Desert; it has 27. 

The proportion of the world’s deserts covered in sand varies greatly. AUSTRALIA’s large desert is the sandiest, more than 50 percent of it under sand. North American deserts’ 2-percent coverage makes that continent’s deserts the least sandy. North America has no ergs as a result. The continent’s largest dune fields—the Algodones in CALIFORNIA, White Sands in NEW MEXICO, and Great Sand Dunes in COLORADO—are too small to qualify as ergs.