SAHARA

Kerzaz oasis on Wadi Saoura, western Sahara, Alg. (from Arabic sahara', desert), largest tropical desert in the world, encompassing almost all of northern Africa. The Sahara is bordered by the Atlantic Ocean to the west, the Atlas Mountains and the Mediterranean Sea to the north, the Red Sea to the east, and the Sahel, a transitional zone of semidesert steppe and thorn scrub, to the south. The Sahara includes portions of 11 countries: Western Sahara, Morocco, Algeria, Tunisia, Libya, Egypt, Mauritania, Mali, Niger, Chad, and The Sudan. The principal topographic features of the Sahara include shallow, seasonally inundated basins and large oasis depressions; extensive stony plains; rock-strewn plateaus; abrupt mountains; and sand sheets, dunes, and sand seas. The highest elevation is the 11,204-foot (3,415-metre) summit of Mount Koussi in the Tibesti Mountains in Chad; the lowest elevation, 436 feet (133 m) below sea level, occurs in the Qattara Depression in Egypt. The soils of the Sahara are typically low in organic matter and are biologically inactive. The soils found in depressions are frequently saline. The Sahara was established as a climatic desert around five million years ago, during the Early Pliocene Epoch (5.3 to 3.4 million years ago). Since that time, it has undergone repeated oscillations between drier and more humid conditions. The desert is presently dominated by two climatic regions. The dry subtropical north exhibits wide seasonal as well as diurnal temperature ranges. Most precipitation falls in the winter months, as rain or sometimes snow, though flash flooding is a common summer phenomenon in otherwise dry areas. Hot, southerly, dust-bearing winds are most prevalent in spring and are rare in summer. In the southern Sahara, seasonal interactions between the stable continental subtropical air mass and the southerly, unstable maritime tropical air mass produce a dry tropical climate. Diurnal temperature variations are less pronounced than in the north. Dust-laden northeasterly winds are common in winter. The plants found most frequently in the various zones of the Sahara include grasses; numerous herbs; date and doum palms; and tamarisk and acacia trees. The characteristic mammals of the desert include several species of hare, hedgehog, hyena, and gazelle. Resident and migratory birdlife exceeds 300 species. Chameleons and cobras are common rock- and dune-dwellers. Huge areas of the Sahara are wholly empty, but wherever meagre vegetation or reliable water sources occur, scattered clusters of inhabitants survive in fragile ecological balance. The density of the largely nomadic population is less than one person per square mile. Sedentary living is restricted to oasis areas. The Sahara is rich in metallic minerals such as iron, copper, manganese, tin, nickel, chromium, zinc, lead, cobalt, silver, and gold. Inaccessibility, however, limits exploitation. Major oil and gas reserves and vast underground reserves of water have also been found. The principal transportation routes run from west to east with a network of recognized tracks emanating from them. Ground travel is supplemented by numerous international air services. Area 3,320,000 square miles (8,600,000 square km). The Sahara. (from Arabic sahara', desert), largest desert in the world. Filling nearly all of northern Africa, it measures approximately 3,000 miles (4,800 kilometres) from east to west and between 800 and 1,200 miles from north to south and has a total area of some 3,320,000 square miles (8,600,000 square kilometres). The Sahara is bordered in the west by the Atlantic Ocean, in the north by the Atlas Mountains and Mediterranean Sea, in the east by the Red Sea, and in the south by a zone of ancient, immobile sand dunes aligned with latitude 16 N. Additional reading E.-F. Gautier, Sahara: The Great Desert (1935, reissued 1987; originally published in French, 2nd ed., 1928), provides a wealth of information by an eminent geographer long acquainted with the desert. A more popular introduction to the Sahara, by a naturalist who traveled there extensively, is Jeremy Swift, The Sahara (1975), a Time-Life book. Detailed discussions of the geologic past and prehistory of the desert are contained in Martin A.J. Williams and Hugues Faure (eds.), The Sahara and the Nile (1980). William G. McGinnies, Bram J. Goldman, and Patricia Paylore (eds.) Deserts of the World (1968), includes detailed appraisals of research on the physiography, hydrology, soils, weather and climate, vegetation, and fauna of the Sahara. The most comprehensive climatology available for the desert is Jean Dubief, Le Climat du Sahara, 2 vol. (195963). An excellent introduction to the vegetation of the desert is P. Quzel, Analysis of the Flora of Mediterranean and Saharan Africa, Annals of the Missouri Botanical Garden, 65:479534 (1978). Animal life is described in P.-L. Dekeyser and J. Derivot, La Vie animale au Sahara (1959). Prehistoric rock art is discussed in Henri Lhote, The Search for the Tassili Frescoes: The Story of the Prehistoric Rock-paintings, 2nd ed. (1973; originally published in French, 1973). There are several excellent studies of the peoples of the Sahara: Julio Caro Baroja, Estudios saharianos (1955), a detailed description of the little-known peoples of the western desert; Lloyd Cabot Briggs, Tribes of the Sahara (1960), a more general study, focusing on the central regions; and UNESCO, Nomades et nomadisme au Sahara (1963), discussing the nomadic peoples. The most detailed 19th-century travelers' reports are by Henry (Heinrich) Barth, Travels and Discoveries in North and Central Africa, 5 vol. (185758, reissued in 3 vol., 1965; originally published in German, 185758); and Gustav Nachtigal, Sahara and Sudan, 4 vol. (197183; originally published in German, 3 vol., 187989). Jeffrey Allman Gritzner Study and exploration Classical accounts describe the Sahara much as it is todaya vast and formidable barrier. The Egyptians controlled only their neighbouring oases and, occasionally, lands to the south; the Carthaginians apparently continued the commercial relationships with the interior that had been established during the Bronze Age. Herodotus described a desert crossing by an expedition of Berbers during the 5th century BC, and Roman interest in the Sahara is documented in a series of expeditions between 19 BC and AD 86. The descriptions of the Sahara in the works of Strabo, Pliny the Elder, and Ptolemy reflect growing interest in the desert. Geographic exploration, sponsored by the 'Abbasids, Fatimids, Mamluks, and other courts in the Middle East, North Africa, and Moorish Spain, was widespread during the medieval period. Descriptions of the Sahara are contained in the works of numerous Arab writers, including al-Ya'qubi, ash-Sharif al-Idrisi, and Ibn Battuta. Medieval travelers with religious and commercial motives contributed further to an understanding of the Sahara and its peoples. Abraham Cresque's Catalan Atlas, published for Charles V of France in about 1375, renewed European interest in the desert. The atlas contained information based upon the knowledge of Jewish traders active in the Sahara. Its publication was followed by a period of intense Portuguese, Venetian, Genoese, and Florentine activity there. Particularly well documented are the travels of such 15th-century explorers as Alvise Ca' da Mosto, Diogo Gomes, and Pedro de Sintra. Growing interest in the Sahara within northern Europe was reflected in the travels and writings of the 17th-century Dutch geographer Olfert Dapper. Subsequent European exploration of the Sahara, much of it incidental to interest in the major waterways of interior Africa, began in earnest in the 19th century. Attempts to determine the course of the Niger River took the British explorers Joseph Ritchie and George Francis Lyon to the Fezzan area in 1819, and in 1822 the British explorers Dixon Denham, Hugh Clapperton, and Walter Oudney succeeded in crossing the desert and discovering Lake Chad. The Scottish explorer Alexander Gordon Laing crossed the Sahara and reached the fabled city of Timbuktu in 1826, but he was killed there before he could return. The French explorer Ren Cailli, disguised as an Arab, returned from his visit to Timbuktu by crossing the Sahara from south to north in 1828. Other notable expeditions were undertaken by the German geographer Heinrich Barth (184955), the French explorer Henri Duveyrier in 185962, and the German explorers Gustav Nachtigal (186975) and Gerhard Rohlfs (186278). After the military occupation of the Sahara by the various European colonial powers, more detailed exploration took place; and by the end of the 19th century the main features of the desert were known. Although 20th-century political, commercial, and scientific activities have greatly increased knowledge of the Sahara, vast tracts remained remote, little known, and difficult to reach. Ronald Francis Peel Jeffrey Allman Gritzner The economy Resources During the century of colonial dominion over the Sahara, which lasted from the mid-19th to the mid-20th century, there was little fundamental change, except for military pacification; colonial powers were little interested in the economic development of what appeared to be an unpromising region. After World War II, however, the discovery of oil, in particular, attracted international interest and investment. Within a few years major discoveries had been made, particularly in mineral resources. Metallic minerals are of considerable economic importance. Algeria possesses several major deposits of iron ore, and the reserves at Mount Ijill, in western Mauritania, are substantial; less extensive deposits have been found in Egypt, Tunisia, Morocco, Western Sahara, and Niger. Near Akjoujt, in southwestern Mauritania, lie substantial quantities of copper ore; extensive manganese deposits occur south of Bchar, Alg. Uranium is widely distributed in the Sahara and has been particularly important in Niger. A broad range of other economically significant minerals have been found in the Ahaggar, Ar, Tibesti, and Eglab regions. Rich phosphate deposits exist in Morocco and Western Sahara, and smaller deposits have been found elsewhere. Fuel resources include coal, oil, and natural gas. Sources of coal include anthracite seams in Morocco and bituminous fields near Bchar. Following the discovery of oil near I-n-Salah, Alg., after World War II, major reserves have been found in the Western Desert of Egypt, northeastern Libya, and northeastern Algeria. Minor reserves exist in Tunisia and Morocco, as well as in Chad and Niger in the south. Deposits of oil shale have also been discovered in the Sahara. Major fields of natural gas are exploited in Algeria, and minor fields exist in Egypt, Libya, and Tunisia. As a result of geologic and oil prospecting, vast underground reserves of water have also been found in a number of sedimentary basins, mainly within sandstone formations. Some recoverable water is also present in surface sand formations. Economic development of the desert, however, offers enormous difficulties and has not changed the traditional Sahara. Oil and ore extraction have brought modern technology and improved communications to scattered locations, but such activities provide limited opportunities for local employment. Although oil revenues offer the means for desert development, the more immediate and attractive returns possible in inhabited coastal regions tend to take priority. The underground water offers possibilities for major developments in both agriculture and industry; but exploitation on a large scale would be expensive. Heavy exploitation would also result in progressive depletion, and hydrological changes might increase the threat of locust plagues, as locusts congregate into swarms when food supplies are restricted, multiply, and then occupy larger areas when conditions improve. The desert peoples have benefited little from mineral exploitationperhaps indeed the reverse. The decline in nomadic pastoralism, started by pacification, has been accelerated by changing economic conditions and official settlement policies (for nomads are administratively inconvenient). Widespread environmental degradation further encourages the drift of nomads to oases and towns, with resultant overcrowding and poverty. High wages in the oil fields attract labour but disrupt traditional life, and the jobs are relatively few and impermanent. Of the traditional desert productsanimal skins and wool, surplus fruits, saltonly dates (particularly the daglet nour of the northern oases) retain much commercial importance. Salt, although still extracted and sent south to the western Sudan region, now competes with cheap imported salt. Industrial occupations to relieve growing unemployment have as yet made little progress. As manufacturing costs increase in the advanced and overcrowded Western countries, however, the high costs of Saharan development may become more acceptable. It may be possible, for example, to utilize nuclear energy and more efficient solar energy converters to raise deep-seated water (and, if necessary, to remove the salt) for new settlements and to provide power for industries. Tourism has grown considerably since 1950, although the difficulties of transport and of providing accommodations has limited it largely to the Sahara's fringes. Transportation Traditionally, travel in the Sahara was by camel caravan and was slow, arduous, and dangerous. To the hazards of losing the way, excessive heat, stifling sandstorms, and death by starvationor more probably thirstwere added those of attack by raiders. Despite all this, trans-Saharan trade along caravan routes linking oases has persisted from very early times. Most of the principal routes were west of the Tibesti Mountains and tended to shift somewhat over time, although the easternmost of thesewhich ran northward from Lake Chad to Bilma (now in Niger) and through the Fezzan region to Tripoliwas used continuously through the centuries. East of the Tibesti Mountains oases are few, but the darb al-arba'in (road of the forty ), west of the Nile, was a former slave route. Gold, ivory, slaves, and salt were major items of trade in the earlier days, but today camel caravans have almost ceased, except for a residual trade in salt from Mount Ijill, Bilma, and Taoudenni, Mali. The main routes remain in use, however, by specially equipped motor trucks, often traveling in convoys. Year by year modern highways are extended further along the ancient trade routes into the desert. The French initiated a trans-Saharan bus service, which still operates. Off of the main routes a network of recognized tracks are motorable, with care; but in the open desert four-wheel drive is virtually essential, with at least two vehicles, ample spares, and large emergency supplies of fuel, food, and waterparticularly in summer, when special regulations apply to all travelers. In large areas maps are inadequate, and navigational methods may be necessary. To supplement ground travel, numerous international air services cross the Sahara on scheduled flights, while local services link the main inhabited centres to one another. Railways, with the abandonment of the Trans-Saharan at Abadla (near Bchar, Alg.), have been little developed except for a line built to transport minerals in Mauritania. The people Although as large as the United States, the Sahara (excluding the Nile valley) is estimated to contain only some 2.5 million inhabitantsless than 1 person per square mile (0.4 per square kilometre). Huge areas are wholly empty, but wherever meagre vegetation can support grazing animals or reliable water sources occur, scattered clusters of inhabitants have survived in fragile ecological balance with one of the harshest environments on earth. Long before recorded history, the Sahara was evidently more widely occupied. Stone artifacts, fossils, and rock art, widely scattered through regions now far too dry for occupation, reveal the former human presence, together with that of game animals, including antelopes, buffalo, giraffe, elephant, rhinoceros, and warthog. Bone harpoons, accumulations of shells, and the remains of fish, crocodiles, and hippopotamuses are associated with prehistoric settlements along the shores of ancient Saharan lakes. Among some groups, hunting and fishing were subordinated to nomadic pastoralism, after domesticated livestock appeared in the Sahara almost 7,000 years ago. The cattle-herding groups of the Tnr region of Niger are believed to have been either ancestral Berbers or ancestral Zaghawa; sheep and goats were apparently introduced by groups associated with the Capsian culture of northeastern Africa. Direct evidence of agriculture first appears about 6,000 years ago with the cultivation of barley and emmer wheat in Egypt; these appear to have been introduced from Asia. Evidence of the domestication of native African plants is first found in pottery from about 1000 BC discovered in Mauritania. The cultivators have been associated with the Gangara, the ancestors of the modern Soninke. Archaeological evidence suggests that the Sahara was increasingly inhabited by diverse populations, and plant and animal domestication led to occupational specialization. While the groups lived separately, the proximity of settlements suggests an increasing economic interdependence. External trade also developed. Copper from Mauritania had found its way to the Bronze Age civilizations of the Mediterranean by the 2nd millennium BC. Trade intensified with the emergence of the Iron Age civilizations of the Sahara during the 1st century BC, including the civilization centred in Nubia. The greater mobility of nomads facilitated their involvement in the trans-Saharan trade. Increasing aridity in the Sahara is documented in the transition from cattle and horses to camels. Although camels were used in Egypt by the 6th century BC, their prominence in the Sahara dates from only the 3rd century AD. Oasis dwellers in the Sahara were increasingly subject to attack by the Sanhaja (a Berber clan) and other camel-mounted nomadsmany of whom had entered the desert to avoid the anarchy and warfare of the late Roman period in North Africa. Many of the remaining oasis dwellers, among them the Haratin, were subjugated by the nomads. The expansion of Islam into North Africa between the 7th and 11th centuries prompted additional groups of Berbers, as well as Arab groups wishing to retain traditional beliefs, to move into the Sahara. Islam eventually expanded through the trade routes, becoming the dominant social force in the desert. Despite considerable cultural diversity, the peoples of the Sahara tend to be categorized as pastoralists, sedentary agriculturalists, or specialists (such as the blacksmiths variously associated with herders and cultivators). Pastoralism, always nomadic to some degree, occurs where sufficient scanty pasturage exists, as in the marginal areas, on the mountain borders, and in the slightly moister west. Cattle appear along the southern borders with the Sahel, but sheep, goats, and camels are the mainstays in the desert. Major pastoral groups include the Regeibat of the northwestern Sahara and the Chaamba of the northern Algerian Sahara. Hierarchical in structure, the larger pastoral groups formerly dominated the desert. Warfare and raids (ghazw) were endemic, and in drought periods wide migrations in search of pasture took place, with heavy loss of animals. The Tuareg (who call themselves Kel Tamasheq) were renowned for their warlike qualities and fierce independence. Although they are Islamic, they retain a matriarchal organization, and the women of the Tuareg have an unusual degree of freedom. The Moorish groups to the west formerly possessed powerful tribal confederations. The Teda, of the Tibesti and its southern borderlands, are chiefly camel herders, renowned for their independence and for their physical endurance. Kerzaz oasis on Wadi Saoura, western Sahara, Alg. In the desert proper, sedentary occupation is confined to the oases, where irrigation permits limited cultivation of the date palm, pomegranate, and other fruit trees; such cereals as millet, barley, and wheat; vegetables; and such specialty crops as henna. Cultivation is in small gardens, maintained by a great expenditure of hand labour. Irrigation utilizes ephemeral streams in mountain areas, permanent pools (gueltas), foggaras (inclined underground tunnels dug to tap dispersed groundwater in the beds of wadis), springs ('ayn), and wells (bi'r). Some shallow groundwaters are artesian, but it is often necessary to use water-lifting devices such as the shadoof (a pivoted pole and bucket) and the animal-driven noria (a Persian wheel with buckets). To a limited extent diesel pumps have replaced these ancient means in more accessible oases. Water availability strictly limits oasis expansion, and, in some, overuse of water has produced a serious fall in the water level, as in the oases of the Adrar region of Mauritania. Salinization of the soil by the fierce evaporation, as well as burial by encroaching sand, are further dangers; the latter, as in the Souf oases of Algeria, necessitates constant hand labour in clearing.