Nubian Desert | Article about Nubian Desert by The Free Dictionary Nubian Desert | Article about Nubian Desert by The Free Dictionary Also found in: Dictionary , Thesaurus , Wikipedia . Nubian Desert, eastern region of the Sahara Desert, c.157,000 sq mi (407,000 sq km), NE Republic of Sudan, NE Africa, between the Nile and the Red Sea. The arid region, largely a sandstone plateau, has numerous wadis flowing toward (but never reaching) the Nile, whose great bends are entrenched in the western part of the region. Nubian Desert a desert in Africa, lying chiefly in the Sudan between the Nile River and the Red Sea. The Etbai Range separates the desert from the Red Sea. The surface is a plateau descending in steps from east to west from 1,000 m to 350 m. On the plateau are inselbergs rising to 1,240 m in the west. The ancient rocks of the Nubian-Arabian Shield and Nubian sandstones are exposed in the east and covered by sand in the west.

The plateau is dissected by a dense network of dry riverbeds. The annual precipitation is about 25 mm, and the sparse vegetation consists primarily of xerophytic grasses and prickly shrubs and semishrubs. There is livestock herding. A railroad and a highway cross the desert, connecting the cities of Wadi Haifa and Abu Hamed on the Nile River. Nubian Desert a desert in the NE Sudan, between the Nile valley and the Red Sea: mainly a sandstone plateau Sudan Sudan Official name: Republic of the Sudan Area: 2,505,810 square kilometers (967,499 square miles) Highest point on mainland: Mount Kinyeti (3,187 meters/10,456 feet) Lowest point on land: Sea level Hemispheres: Northern and Eastern P.M.

= noon GMT Longest distances: 2,192 kilometers (1,362 miles) from south-southeast to north-northwest; 1,880 kilometers (1,168 miles) from east-northeast to west-southwest Land boundaries: 7,687 kilometers (4,776 miles) total boundary length; Egypt 1,273 kilometers (791 miles); Ethiopia 1,606 kilometers (998 miles); Kenya 232 kilometers (144 miles); Uganda 435 kilometers (270 miles); Democratic Republic of the Congo 628 kilometers (390 miles); Central African Republic 1,165 kilometers (724 miles); Chad 1,360 kilometers (845 miles); Libya 383 kilometers (238 miles); Eritrea 605 kilometers (376 miles) Coastline: 853 kilometers (530 miles) Territorial sea limits: 22 kilometers (12 nautical miles) 1 LOCATION AND SIZE Sudan is located in northeast Africa on the western border of the Red Sea.

It is the largest country in Africa and shares borders with Egypt, Libya, Chad, the Central African Republic, Uganda, Kenya, Ethiopia, and Eritrea. With an area of about 2,505,810 square kilometers (967,499 square miles), it is slightly more than one-fourth the size of the United States. Sudan is divided into twenty-six states. 2 TERRITORIES AND DEPENDENCIES Sudan has no outside territories or dependencies. 3 CLIMATE Sudan has an equatorial climate. The northern plains and desert region are hot and dry with maximum temperatures reaching 42°C (108°F) from March through June. November through February are the coolest months, with average temperatures of 32°C (90°F) and nighttime lows of 4°C (40°F). Average temperatures in the central and southern regions are 27°C (80°F) and 29°C (85°F) respectively. Rainfall increases from north to south. In the north, annual rainfall totals about 10 centimeters (4 inches).

The southern regions receive 76 to 127 centimeters (30 to 50 inches) of rain during the long rainy season; as a result, these areas support a rich variety of tall grasses, shrubs, and trees. The lush vegetation in the south contrasts sharply with the deserts of Northern Province, where the occasional rains vanish in the parched sand and vast areas are devoid of both vegetation and people. 4 TOPOGRAPHIC REGIONS Sudan is an immense, sparsely populated plain, with plateaus or mountains near the borders in the west, the southeast, and along the Red Sea coast in the northeast. The most prevalent landscape is semiarid savannah, a mixture of short grasses, scattered brush, and short trees. Narrow belts of irrigated cropland, no more than a few miles wide, bisect the northern savannah and deserts along the main Nile River; these farmlands also run along the White Nile, the Blue Nile, and the Atbara Rivers. They contrast sharply with the arid savannah or barren desert which is just beyond the limits of irrigation.

Only 5 percent of the land in Sudan is arable; of the remaining terrain, 24 percent is meadows and pastures, 20 percent is forest and woodland, and 51 percent is semiarid desert. 5 OCEANS AND SEAS Seacoast and Undersea Features Sudan has an eastern coast on the Red Sea, which is a narrow, landlocked sea that separates Africa from the Arabian Peninsula. In the north, it links to the Mediterranean through the Gulf of Suez and the Suez Canal. In the south, the sea links to the Gulf of Aden and the Arabian Sea through the strait of Bab el Mandeb. The Red Sea is therefore a major shipping route between the Mediterranean Sea and the Gulf of Aden. At its widest point, it is only 326 kilometers (205 miles). The Red Sea is rather deep, with an average depth of 500 meters (1,640 feet). It reaches a maximum depth of 2,000 meters (6,562 feet), and it features red coral reefs and extensive coral gardens.

Sea Inlets and Straits Natural harbors of the Red Sea exist at Port Sudan (Bur Sudan) and Sawākin. 6 INLAND LAKES Sudan has very few lakes. The largest ones are artificial, resulting from dams on the Blue Nile and Upper Nile Rivers. The backwaters of the Aswan Dam in Egypt created Lake Nubia, the largest lake in Sudan. The lake begins in Egypt and extends into Sudan as far as the northern terminus of the Sudanese railway at Wadi Halfa. Its total surface area during the wet season is 968 square kilometers (373 square miles). 7 RIVERS AND WATERFALLS With a total length of about 6,693 kilometers (4,160 miles), the Nile is the longest river in the world, although other rivers carry more water. The Nile is a combination of the White Nile, which originates in Lake Victoria in Uganda and Tanzania, and the Blue Nile, which originates in Ethiopia. These rivers meet in Sudan near the city of Khartoum.

From the confluence of the White and Blue Nile Rivers near Khartoum, the Upper Nile winds northward through this desert area for a distance of 1,287 kilometers (800 miles) inside Sudan. It provides the only water for the narrow strips of cultivation along the riverbanks. Virtually no rain falls in the area between Atbara and the Egyptian frontier at Wadi Halfa; Wadi Halfa is often completely rainless for years at a time. The settlements along the Nile depend on various types of irrigation or periodic flooding for their livelihood. Within Sudan, the Blue Nile experiences seasonal flooding caused by torrential rains in the Ethiopian highland regions. Half of the people of Sudan are dependent on waters from these floods. During flood times, the flow of the Blue Nile may be sixty times greater than that of its low-water period. An important tributary to the Upper Nile is the Atbara River, similar in seasonal behavior to the Blue Nile and also originating in the mountains of Ethiopia. It traverses northwest across eastern Sudan and empties into the Nile at the town of Atbara. The gradient of the Nile from Khartoum to Wadi Halfa on the northern border of Sudan is very steep.

Along this lower reach are five of the Nile's six cataract areas of swift, rough water. The Nile crosses the northern border of Sudan into Egypt and eventually empties into the Mediterranean Sea. All perennial streams of significant size in Sudan are part of the Nile system. There are also numerous wadis, or intermittent streams, which flow only part of the year. Some drain into the Nile during the rainy season and stand empty at other times. Others drain into swamps that have no outlet to a river or simply disappear into the sands of an inland basin during the dry months. For example, the Wadi Howar and the Wadi Al-Ku, both originating in the Teiga Plateau region, disappear into the desert. Another stream of similar origin, the Wadi Azum, eventually reaches the Lake Chad drainage system to the west. Some of these intermittent streams carry large amounts of water during the rainy season and support local areas of agriculture. The Mareb, also known as the Gash or Al-Qāsh in Sudan, and the Baraka River flow into northeast Sudan from the Eritrean highlands during the months of July, August, and September.

The Mareb River provides water for important irrigation schemes north of Kassalā and the Baraka feeds the Tawkar delta near the Red Sea coast. The Bahr el Arab in southwestern Sudan is another important seasonal river. Permanent swamps surround the river systems in the southern provinces and Upper Nile, covering about 129,500 square kilometers (50,000 square miles), where there is an excess of water for most of the year. This phenomenon is best characterized by the Sudd, a vast region of swamps and marshes covering an area of about 7,770 square kilometers (3,000 square miles) and extending from Boma National Park several hundred miles northwestward to the Al-Ghazāl River, ending at the Machar Marshes near the Ethiopian border. The vast swamp and marsh area is as monotonous as the featureless plains farther north, but there is considerable variety of terrain and vegetation in the uplands south of the swamps, particularly near the Uganda and Kenya borders. The largest swamp in the Sudd, Badigeru Swamp, is located between the Al-Jabal and Boma National Park.

Lotagipi Swamp is located in the southeast corner of Sudan, at the junction with Kenya and Ethiopia. 8 DESERTS A line running east to Atbara and Port Sudan from the western frontier at 16°N latitude defines the approximate southern limit of desert, which covers the northern quarter of Sudan. The Libyan Desert extends into Sudan from the northwest. In the northeast, the Nubian Desert covers the area between the Nile and the Red Sea Hills. These deserts are part of the larger Sahara Desert. The desert west of the Nile supports only a few Arab nomads who cover great expanses of the parched country in search of grazing land for their camels, sheep, or goats. They usually find pastures in the south, where a little rain occurs during most years and grass springs to life. Water is available only in scattered oases, such as Al Atrun in the western desert and Well No. 6 on the railway between Wadi Halfa and Abu Hamand. Terrain in this northern desert consists of broad areas of sand and flintrock with occasional hills of basalt, granite, and limestone, often surrounded by banks of sand deposited by the wind.

9 FLAT AND ROLLING TERRAIN The topography of the country outside the mountains and the Nile valley is basically a flat plain extending some 804 to 965 kilometers (500 to 600 miles) from east to west and more than 1,609 kilometers (1,000 miles) from north to south. It is a part of the broad savannah belt that begins at the southern edge of the Sahara Desert and extends across the African continent. For hundreds of square kilometers the only features relieving the monotony of the Sudanese plain are low rolling hills (sometimes referred to locally as mountains) or extensive sand dunes created thousands of years ago and partially or entirely fixed by vegetation. Soils are composed mainly of clay, much of which is impermeable and difficult to cultivate, or of sand that contains little clay or humus (organic matter). DID YOU KNOW? The country of Sudan lies within the greater region also known as the Sudan. The Sudan region covers an area that is south of the Sahara Desert but north of the equator. It extends from the Atlantic coast of Africa to the mountains of Ethiopia.

The Sahara Desert, which covers an area of 9,065,000 square kilometers (3,500,000 square miles), is the largest desert in the world. It covers the entire region of North Africa, from the Atlantic coast in the west to the Red Sea in the east. It borders the Mediterranean Sea and the Atlas Mountains in the north and extends through the Sudan region. Scientists believe that during the Ice Age (fifty thousand to one hundred thousand years ago), the Sahara was covered with shallow lakes that provided water for large areas of lush vegetation. 10 MOUNTAINS AND VOLCANOES Sudan has four mountain or upland zones. To the northeast near the coast lie the Red Sea Hills. In the west are the Marra, a mountain range that slopes to the border with Chad, and in central Sudan south of El Obeid are the Nuba Mountains, a relatively minor system that rises above the clay plains. The fourth zone includes the Imatong and Dongotona Mountains in the extreme south along the Uganda border. The Red Sea Hills are eroded outcroppings of base rock rising from a narrow coastal plain.

The abruptness of their eastern slope gives rise to gushing torrents during winter rains that are blown in from the sea. The western slopes incline more slowly toward the Nile and receive only light summer rains. North of the Atbara-Port Sudan railway, the hills extend into the desert and are bare of vegetation except in the valleys. South of the railway, however, increased rainfall permits the growth of a few trees and thorny shrubs. The area is inhospitable and supports only semi-nomadic herders, who also cultivate hardy varieties of millet in the wetter valleys. They move their flocks laterally across the mountains or to higher or lower altitudes, depending upon the vagaries of the rainfall at various elevations. The highest of the Red Sea Hills are above 2,133 meters (7,000 feet). The only major mountain range in western Sudan, the Marra, stands near the city of El Fasher, rising above 3,048 meters (10,000 feet) in elevation. The Marra is of volcanic origin and its valleys are relatively fertile.

The upper elevations receive a slightly higher rainfall than the surrounding plains and the relatively rich soil of the valley is more productive. Some of the rocks and peaks have a sculptured appearance resulting from the action of the rains upon the soft volcanic rock. Streams deposit much of the eroded rock on the desert floor below, but on the higher hillsides, artificial terraces of ancient origin retain topsoil and water. Although cultivation is generally dependent upon the seasonal rains, some valleys and terraces are irrigated with water from small perennial mountain streams. DID YOU KNOW? The Pyramids of Meroe, in central Sudan, stand as monuments to the kingdom of Nubia, known as Kush to the Egyptians. Sudanese kings reigned over Nubia for a relatively short period of time, from about 712 B.C. until 657 B.C. The ancient region of Nubia covered part of the area of modern-day southern Egypt and northern Sudan. (Much of this area was submerged recently by the Aswan Dam's creation of Lake Nassar.) When the Sudanese kings controlled the region, the capital of their kingdom was at Meroe, near what is now Khartoum.

More than fifty pyramids that once served as part of the royal cemetery still stand in this desert region. Though smaller than the pyramids of Egypt (the largest of these measures about 51 meters/ 170 feet at its base), the Pyramids of Meroe are the world's largest collection of pyramids in one place. The Nuba Mountains of central Sudan are scattered granitic masses, rising as much as 914 meters (3,000 feet) above a level clay plain. They are covered in many areas by variations of savannah vegetation. Some slopes were once terraced and then abandoned by subsistence farmers. Water is not as scarce in the mountains as in the surrounding plains. Wells are numerous in the open valleys, and a few short mountain streams continue to flow throughout the year. The Imatong and Dongotona Mountains stand in the extreme south, with the lower Didinga Hills flanking them to the east.

The Imatongs are the highest mountains in Sudan, with peaks above 3,048 meters (10,000 feet) including Mount Kinyeti, the highest point in the country, which rises to a height of 3,187 meters (10,456 feet). The Dongotona Mountains, lying east of the Imatongs, reach a maximum height of about 2,529 meters (8,300 feet). Both mountain chains have a considerable coverage of rainforest. 11 CANYONS AND CAVES There are no major caves or canyons in Sudan. 12 PLATEAUS AND MONOLITHS Plateau-like formations characterize the mountainous areas and their foothills and, therefore, tend to rim the country, serving as watersheds for the great Nile basin drainage. The best examples are found in the large Teiga Plateau north of the Marra in the west and the extensive Ironstone Plateau in the southwest. Near the Imatongs and Dongotona Mountains area in the southeast, on the border with Ethiopia, sits the Boma Plateau, the site of a national park.

West of this region, north of the mountains and northeast of Ironstone Plateau, lower plateaus slope generally northward toward the Sudd. In the north, the Libyan Desert runs across the Jebel Abyad Plateau. Along the Red Sea coast in the northeast, there are also some smaller plateaus. 13 MAN-MADE FEATURES There is an extensive system of dams and reservoirs built throughout the course of the Nile River. These dams serve to control flood waters, irrigate agriculture lands, provide drinking water, and generate hydroelectric power. For instance, in Sudan, the Sannar Dam on the Blue Nile allows for irrigation of the Al-Jazirah plain and produces hydroelectric power. The Ar-Rusayris Dam, also on the Blue Nile, helps contain water from Lake Nassar (at the Egyptian border) for use in Sudan. 14 FURTHER READING Books Africa South of the Sahara 2002: Sudan. London: Europa Publishers, 2001. Lobban, Jr. Richard A., Robert S. Kramer, and Carolyn Fluehr-Lobban. Historical Dictionary of the Sudan. 3rd ed.

Meutchen, NJ: Scarecrow Press, 2002. Moorehead, Alan. The Blue Nile. New York: HarperTrade, 2000. Williams, Martin A. J., and D. A. Adamson. Land Between Two Niles: Quaternary Geology and Biology of the Central Sudan . Salem, NH: MBS, 1982. Web Sites Sahara | Article about Sahara by The Free Dictionary Sahara | Article about Sahara by The Free Dictionary Also found in: Dictionary , Thesaurus , Medical , Acronyms , Wikipedia . Sahara (səhâr`ə) [Arab.,=desert], world's largest desert, c.3,500,000 sq mi (9,065,000 sq km), N Africa; the western part of a great arid zone that continues into SW Asia.

Extending more than 3,000 mi (4,830 km), from the Atlantic Ocean to the Red Sea, the Sahara is bounded on the N by the Atlas Mts., steppelands, and the Mediterranean Sea; it stretches south c.1,200 mi (1,930 km) to the Sahel Sahel , name applied to the semiarid region of Africa between the Sahara to the north and the savannas to the south, extending from Senegal and Mauritania on the west, through Mali, N Burkina Faso, Niger, N Nigeria, and Chad, to Sudan and Eritrea on the east. ..... Click the link for more information. , a steppe in W and central Africa that forms its southern border. The desert includes most of Western Sahara, Mauritania, Algeria, Niger, Libya, and Egypt; the southern portions of Morocco and Tunisia; and the northern portions of Senegal, Mali, Chad, and Sudan. The E Sahara is usually divided into three regions—the Libyan Desert Libyan Desert, northeast part of the Sahara Desert, NE Africa, in SW Egypt, E Libya, and NW Sudan; called the Western Desert in Egypt.

It is a region of sand dunes, stony plains, and rocky plateaus. There are few inhabitants and little traffic across it. ..... Click the link for more information. , which extends west from the Nile valley through W Egypt and E Libya; the Arabian Desert Arabian Desert or Eastern Desert, c.86,000 sq mi (222,740 sq km), E Egypt, bordered by the Nile valley in the west and the Red Sea and the Gulf of Suez in the east. It extends along most of Egypt's eastern border and merges into the Nubian Desert in the south. ..... Click the link for more information. , or Eastern Desert, which lies between the Nile valley and the Red Sea in Egypt; and the Nubian Desert Nubian Desert, eastern region of the Sahara Desert, c.157,000 sq mi (407,000 sq km), NE Republic of Sudan, NE Africa, between the Nile and the Red Sea. The arid region, largely a sandstone plateau, has numerous wadis flowing toward (but never reaching) the Nile, whose great ..... Click the link for more information. , which is in NE Sudan.

Regions of sand dunes (erg) occupy only about 15% of the Sahara; "stone deserts," consisting of plateaus of denuded rock (hammada) or areas of coarse gravel (reg), cover about 70% of the region; mountains, oases, and transition zones account for the remainder. Sparse vegetation is found in most parts of the Sahara, with the exception of the sand dune regions. High mountain massifs rise in the central regions; they are the Ahagger (Hoggar) in S Algeria, which rises to more than 9,000 ft (2,740 m); the Tibesti Massif in N Chad, which rises to more than 11,000 ft (3,350 m); and the Aïr Mountains (Azbine) in N Niger, which rise to more than 6,000 ft (1,830 m). The mountains are deeply dissected and were in the past infamous for the shelter they provided to marauders preying on desert traffic.

From west to east the four principal land routes across the desert are from Colomb-Bechar to Dakar; from Colomb-Bechar to Gao and Timbuktu by way of Reganne; from Touggourt to Agadez and Kano by way of In-Salah; and from Tripoli to Ghat. Climate The Sahara has one of the harshest climates in the world. Located in the trade winds belt, the region is subject to winds that are frequently strong and that blow constantly from the northeast between a subtropical high-pressure cell and an equatorial low-pressure cell. As air moves downward from the high-pressure into the low-pressure cell, it becomes warmer and drier. The desiccating and dust-laden winds are sometimes felt north and south of the desert, where they are variously known as sirocco, khamsin, simoom, and harmattan. The northern slopes of the Atlas Mts. intercept most of the moisture from winds blowing inshore from the Mediterranean Sea. Border zones on the north and south, where the desert merges with the steppe, receive about 10 in.

(25 cm) of rain a year with some seasonal regularity, but over most of the region rainfall is sparser, with an average annual total of less than 5 in. (12.7 cm); rainfall is usually torrential when it occurs after long dry periods that sometimes last for years. The region's low relative humidity rarely exceeds 30% and is often in the 4% to 5% range. Daytime temperatures are high, averaging 86&degF; (30&degC;) and often over 100&degF; (37.5&degC;). Heat loss is rapid at night, and the diurnal range can be as great as 70&degF; (38&degC;). Freezing temperatures are not uncommon at night from December to February. Water and Other Resources The Nile and Niger rivers, both fed by rains outside the desert, are the only permanent rivers in the region. Water is present at or just below the surface gravel in wadis (intermittent streams) that radiate from the mountain massifs, in scattered oases where the water table comes to the surface, and at greater depths in huge underground aquifers.

The aquifers are believed to be filled with water dating from the Pleistocene epoch, when the Sahara was much wetter than it is today and had very large lakes. The more than 20 lakes (called chotts in the north) and areas of salt flats and boggy salt marshes are also considered relics from this pluvial period. Important discoveries of minerals, oil, and gas have been made in the Sahara. There are huge oil and gas deposits in Algeria and Libya, but in most cases, inaccessibility has delayed exploitation. In searching for oil reserves, underground deposits of water also have been found. Extensive iron ore deposits are worked in the Fort Gouraud area of Mauritania. Salt is still mined, as in the past, at Taoudenni, Mali, and at Bilma, Niger, and is transported, as in the days of the great medieval kingdoms of W Africa, by camel caravans across the desert. People Two thirds of the Sahara's estimated 2 million inhabitants (excluding those in the Nile valley) are concentrated in oases where date palms, fruits, vegetables, grains, and other crops are produced under irrigation.

Nomads, with herds of sheep and goats and with camels for transportation, predominate in drier areas and continue to use oases (including modern oases created by the drilling of wells), as in centuries past, for water, trade, and provisioning stops. The principal ethnic groups of the Sahara are the Tuareg (of Berber origin), who dominate the mountains of the central Sahara; the peoples of mixed Berber and Arab origin in W Sahara; and the Tibu (Tébu), who dominate the Tibesti Massif. History The Sahara has undergone a series of wet periods, the most recent occurring c.5,000–10,000 years ago; it was not until c.3000 B.C. that the Sahara transformed into its present arid state. There is dispute as to whether the desertification of the region has continued into historic time. Those who support this theory contend that increasing aridity is the reason for the recorded advance of desert conditions into areas under cultivation in Roman times in the north and more recently (since the late 1960s) in the south.

Opponents of this view explain such changes as being the result of alterations in land-use practices and neglect of water-supply and irrigation systems. The camel was introduced probably in the 1st cent. A.D. and facilitated occupation by nomads (first the Berbers, later the Arabs), who lived in interdependence with the oasis dwellers, providing protection against enemies in exchange for supplies of food and water. A profitable trans-Saharan trade in gold and slaves from W Africa, salt from the desert, and cloth and other products from the cities on the Mediterranean coast was carried on by the nomads. The first European explorers to travel in the Sahara were Friedrich Horneman in 1805 and Mungo Park in 1806. Some areas of the Sahara remain virtually unexplored, although a network of air and automobile routes now crosses the desert and links the major oases and mining areas. Bibliography See C. Kruger et al., Sahara (tr. 1969); M. Williams and H. Faure, ed., The Sahara and the Nile: Quarternary Environments and Prehistoric Occupation in Northern Africa (1980); J.

Cloudsley-Thompson, ed., Key Environments: Sahara Desert (1984); E. Gautier, Sahara (1987). Sahara (from the Arabic sahra, “desert”), a desert in North Africa and the largest tropical desert in the world, occupying roughly one-quarter of the African continent. The desert occupies southern Morocco and Tunisia, most of Algeria, Mauritania, Libya, and Egypt, and the northern parts of Mali, Niger, Chad, and the Sudan. It stretches for a maximum of 5,700 km from east to west and as much as 2,000 km from north to south in the middle. Various methods are used to determine the boundaries of the Sahara, including the isohyets for 100 mm and 200 mm, the boundary of fruit-bearing date palms in the north and other botanical characteristics in the south, and indexes of aridity. Some geographers consider the Nile Valley to be the eastern boundary of the Sahara. In view of these differences, estimates of the area of the Sahara vary from 6 to 8 million sq km. Topography.

The relief is dominated by plains with elevations of less than 500 m; along the Atlantic and Mediterranean coasts the plains lie below 200 m. Major uplifts are found only in the central Sahara, where the Ahaggar (Tahat, 3,003 m) and Tibesti (Emi Koussi, 3,415 m) highlands bear traces of active Neogene and Anthropogene volcanism (lava fields and geyser deposits in the Tibesti massif). The highlands are dissected by deep canyons and wadis, the dry beds of ancient and present-day streams. South of the Ahaggar and Tibesti highlands are the Iforas (to 728 m), Air (to 1,900 m), and Ennedi (to 1,310 m) plateaus. There are many nondraining basins, some of them lying below sea level. Among the largest are the Chott Melghir in the Algerian Sahara (26 m below sea level) and the al-Fayyum, Siwa, and Qattara (133 m below sea level) in the Libyan Desert.

The desert landscape is highly diversified. Some 70 percent of the Sahara is occupied by rocky deserts (hammadas), by gravel deserts, called regs in the Algerian Sahara and serirs in the Libyan Desert, by sandy deserts (ergs), and by flat saline plains known as sebkhas. The remainder of the area consists of mountain landscapes with rock and gravel deserts. Thick accumulations of sand covering some 2.2 million sq km are found in the depressions and major wadis. The largest are the Erg Iguidi, Erg Chech, the Great Western Erg, and the Great Eastern Erg. The sands of the ergs, rising in ridges, are stabilized to some extent by xerophytic vegetation. There are ridges with elevations of up to 200–300 m, as well as circular and star-shaped dunes. Shifting sands are found in the southern parts of the northern and northeastern Sahara, in the Idehan Ubari, Idehan Marzuq, Ténéré, and Libyan Desert. Geological structure and minerals.

Geologically, the Sahara constitutes the northwestern part of the African-Arabian Platform, whose Precambrian basement emerges in the Rigaibat, Ahaggar, Tibesti, and al-Uwaynat massifs and in the western projection of the Nubian-Arabian Shield. Together, the outcrops form the central Sahara uplift zone. To the north and south of this zone stretch the north Sahara and south Sahara subsidence zones, filled by Phanerozoic deposits. Minerals include petroleum and gas, iron ore (Kediet Ijill), and copper ore (Akjoujt). The Precambrian basement contains deposits of gold, and ores of rare metals, tungsten, and uranium are associated with younger intrusions. Climate. Excluding the north, which has a subtropical climate, the Sahara has a marked tropical desert climate, dry and hot. The climate is strongly influenced by the northeasterly trade winds that prevail over most of the Sahara throughout the year. The present arid climate has lasted roughly 10,000 years.

During the Ice Age the climate was more humid, and the prehistoric population engaged not only in livestock raising and farming but also in hunting and even fishing, as shown by cliff drawings in various parts of the Sahara. Air dryness (a relative humidity of 30–50 percent), an enormous moisture deficit, and a high rate of evaporation (potentially 2,500–6,000 mm) are characteristic everywhere but in the narrow coastal zones. The north Sahara receives most of the precipitation in winter and the south Sahara, in summer. The annual precipitation, 100–200 mm in the border regions, decreases to less than 50 mm over most of the Sahara plains and is normally less than 100 mm in the mountains. In the interior there may be no rain for several years in a row, although occasional downpours cause flash floods in the wadis and mudflows in the mountains. Abundant morning dew (condensation caused by low nighttime temperatures) is typical for most of the Sahara and promotes the formation of a surface dust crust. Snow falls for a short time in the high parts of the Ahaggar and Tibesti highlands almost every year.

High daytime temperatures and great daily and annual fluctuations in temperature are characteristic. Temperatures may reach 56°-58°C, almost the highest on earth, and the surface of the ground may heat up to 70°-80°C. The mean July temperature reaches 37.2°C at Adrar. Ground frosts occur almost everywhere during winter nights, and in the central mountains nighttime temperatures as low as - 18°C have been recorded. Long windy periods and dust (or sand) storms lasting many days are frequent, with the wind velocity increasing from 3–5 m per sec to 50 m per sec or more. The winds are locally called sirocco, khamsin, or simoom. Rivers and lakes. With the exception of the Nile, there are no permanent streams flowing through the Sahara. After heavy rainfall the dry watercourses of the north Sahara are filled with water, as are the channels of the ancient river network spreading out from the Ahaggar and Tibesti highlands (Igharghar, Tafasaset, and Tamanrasset wadis). Small relict lakes have survived in the marginal regions of the Sahara and in the central mountains.

They are somewhat swampy and often strongly mineralized. The Sahara has large basins of groundwater, including artesian water, most of it occurring in continental Lower Cretaceous sandstones. The groundwater supports life in the oases, which are usually located in low-lying areas where there are springs or where it is easier to establish wells. The north Sahara is richest in groundwater. Here, the underground flow is more abundant, and there are more artesian wells with significant reserves. In the south Sahara groundwater is less abundant and lies deeper, and there is virtually no artesian water. Active drilling for water is under way in the Sahara, and the new basins of underground water that have been discovered are being used for water supply in the petroleum- and gas-producing regions. In the northern Sahara the newly discovered groundwater reserves are used for irrigation as well. Soils and vegetation. The typical soils of most of the Sahara are the primitive soils of tropical deserts and semideserts (gravel, pebble, and sand), frequently saline. Limestone and gypsum crusts ranging in thickness from a few centimeters to 1–2 m are widespread. The vegetation belongs to the Holarctic floristic region and includes many Mediterranean species.

There are roughly 1,200 species of higher plants, although an average of only 150 species are encountered over 1,000 sq km, about one-tenth the number found in Europe and one twenty-fifth the number found in the humid tropics. Differences in the vegetative cover are governed by the Sahara’s position in two climatic zones and by characteristics of the relief and surface lithology (whether the area is a rocky, sandy, or other type of desert). Most of the vegetation consists of perennial drought-resistant grasses and shrubs with extensive and deep (up to 15–20 m) root systems, as well as ephemerals that appear after rainfall. The vegetation is extremely sparse everywhere, and the regs, hammadas, and parts of the sand accumulations are completely devoid of vegetation. The mountain regions, where relicts of Neogene flora have survived and where there are many endemic plants, are richer in vegetation. The most common trees and shrubs in the south Sahara are various species of acacia, tamarisk, Ephedra and Genista. Almost everywhere the vegetation has been strongly affected by human activity—livestock grazing, the gathering of useful plants, and fuel extraction.

As a result of the large-scale destruction of vegetation and the cultivation of light sandy soils, the shifting sands are advancing the oases. In 1974, Algeria launched the Green Wall Project, under which stone pines, eucalyptuses, and other trees were planted to block the advance of the sands over a 1,500-km stretch. In addition to dates, the principal crop, figs, olives, citrus and other fruit, and various vegetables are raised in the oases. Doum palms are grown in the southern oases. Wildlife. The fauna belongs to the Holarctic and Ethiopian zoogeographic regions and includes some 4,000 species, most of them invertebrates. Roughly 40 percent of all the species are African endemics, although not more than 10–12 percent are Sahara species. The highlands of the central Sahara are isolated habitats for typical Sahara animals. Excluding birds, more than 50 percent of which are migratory, there are very few species in the drier regions, where the biomass of animals drops to 2 kilograms per hectare or less.

There are only about 60 species of mammals in the Sahara, among them the addax, the ungulate best adapted to long periods without water and now in danger of extinction, several species of gazelles, the mouflon (Ahaggar and Tibesti highlands), and one species of monkey (Air Plateau and Tibesti Highlands). Predators include fennecs, and, in the border regions, jackals, cheetahs, and hyenas. Common rodents are the gerbils and jerboas; lagomorphs are represented by the Sahara hare. Lizards (skinks, monitors) and snakes (horned vipers, cobras) are found everywhere in large numbers. Small crocodiles inhabit the relict lakes in the Ahaggar Highlands. Most Sahara animals are nocturnal. Population. Excluding the densely populated regions of the Nile Valley and Delta, the Sahara has a population of roughly 3 million, most of whom live in the northern part of the Algerian Sahara, in the western and southern border regions of the Sahara, and in groups of oases (about two-thirds of the population), where the density reaches 1,000 persons per sq km or more.

The present ethnic makeup of the Sahara population is diverse, with Berber-Arab peoples predominating. There are roughly 30,000 Tuareg, nomadic herders related to the Berbers, living in the Ahaggar Highlands and on the Air Plateau. The Negroid Tibbu inhabit the Tibesti Highlands. The chief cities are Touggourt, Ouargla, Laghouat, Touat, and Tidikelt in Algeria, al-Kufrah, Sabhah, Tazerbo, Jaghbub, and Marzuq in Libya, and Siwa, Dakhilah, al-Farafirah, and al-Bahriyah in Egypt. Economy. The traditional occupations of the Sahara population are nomadic livestock raising, the gathering of wild plants and fruits, and farming in the oases. Dates are the principal crop, but grains and vegetables are also raised. The nomads and seminomads raise camels, sheep, and goats. Each spring they set out from the oases with their herds in search of summer pastures.

During the 1950’s and 1960’s the discovery and exploitation of major petroleum and natural gas deposits in the Algerian Sahara and in Libya fundamentally changed the economic significance of the Sahara. It became one of the world’s major petroleum-producing regions. Rock salt is extracted at Taoudenni in Mali, hard coal at Kenadsa in Algeria, iron ore at Kediet Ijill in Mauritania (9.3 million tons in 1972), copper ore at Akjoujt in Mauritania, and phosphorites at Bu Craa in the Western Sahara. In addition to the pipelines that connect the petroleum and gas deposits with the Mediterranean ports in Algeria, Tunisia, and Libya, motor-vehicle and air transport are important. The Trans-Sahara Highway from Algeria to Niger (Agades) has an asphalt surface as far as Aïn Salah. A railroad connects Abadía with northern Algeria and Morocco. Touggourt is linked by rail with the Mediterranean coast, and ore is carried by rail from Ijil to the Atlantic coast.

REFERENCES Sudan - GEOGRAPHY GEOGRAPHY Sudan Table of Contents Sudan is Africa's largest country, embracing 2,505,813 square kilometers of northeast and central Africa. It consists of a huge plain bordered on three sides by mountains: to the east the Red Sea Hills, to the west Jabal Marrah, and on the southern frontier the Didinga Hills and the Dongotona and Imatong mountains. Jutting up abruptly in the south-central region of this vast plain are the isolated Nuba Mountains and Ingessana Hills, and far to the southeast, the lone Boma Plateau near the Ethiopian border. Spanning eighteen degrees of latitude, the plain of the Sudan includes from north to south significant regions with distinctive characters--northern Sudan, western Sudan, the central clay plains, eastern Sudan, the southern clay plains, and the Jabal Hadid, or Ironstone Plateau, and southern hill masses. Northern Sudan, lying between the Egyptian border and Khartoum, has two distinct parts, the desert and the Nile Valley. To the east of the Nile lies the Nubian Desert; to the west, the Libyan Desert. They are similar--stony, with sandy dunes drifting over the landscape.

There is virtually no rainfall in these deserts, and in the Nubian Desert there are no oases. In the west there are a few small watering holes, such as Bir an Natrun, where the water table reaches the surface to form wells that provide water for nomads, caravans, and administrative patrols, although insufficient to support an oasis and inadequate to provide for a settled population. Flowing through the desert is the Nile Valley, whose alluvial strip of habitable land is no more than two kilometers wide and whose productivity depends on the annual flood. Western Sudan is a generic term describing the regions known as Darfur and Kurdufan that comprise 850,000 square kilometers. Traditionally, this has been regarded as a single regional unit despite the physical differences. The dominant feature throughout this immense area is the absence of perennial streams; thus, people and animals must remain within reach of permanent wells. Consequently, the population is sparse and unevenly distributed. Western Darfur is an undulating plain dominated by the volcanic massif of Jabal Marrah towering 900 meters above the Sudanic plain; the drainage from Jabal Marrah onto the plain can support a settled population.

Western Darfur stands in stark contrast to northern and eastern Darfur, which are semidesert with little water either from the intermittent streams known as wadis or from wells that normally go dry during the winter months. Northwest of Darfur and continuing into Chad lies the unusual region called the jizzu, where sporadic winter rains generated from the Mediterranean frequently provide excellent grazing into January or even February. The southern region of western Sudan is known as the qoz, a land of sand dunes that in the rainy season is characterized by a rolling mantle of grass and has more reliable sources of water with its bore holes and hafri (sing., hafr) than does the north. A unique feature of western Sudan is the Nuba Mountain range of southeast Kurdufan in the center of the country, a conglomerate of isolated dome-shaped, sugarloaf hills that ascend steeply and abruptly from the great Sudanic plain. Many hills are isolated and extend only a few square kilometers, but there are several large hill masses with internal valleys that cut through the mountains high above the plain.

Sudan's third distinct region is the central clay plains that stretch eastward from the Nuba Mountains to the Ethiopian frontier, broken only by the Ingessana Hills, and from Khartoum in the north to the far reaches of southern Sudan. Between the Dindar and the Rahad rivers, a low ridge slopes down from the Ethiopian highlands to break the endless skyline of the plains, and the occasional hill stands out in stark relief. The central clay plains provide the backbone of Sudan's economy because they are productive where settlements cluster around available water. Furthermore, in the heartland of the central clay plains lies the jazirah, the land between the Blue Nile and the White Nile (literally in Arabic "peninsula") where the great Gezira Scheme (also seen as Jazirah Scheme) was developed. This project grows cotton for export and has traditionally produced more than half of Sudan's revenue and export earnings. Northeast of the central clay plains lies eastern Sudan, which is divided between desert and semidesert and includes Al Butanah, the Qash Delta, the Red Sea Hills, and the coastal plain.

Al Butanah is an undulating land between Khartoum and Kassala that provides good grazing for cattle, sheep, and goats. East of Al Butanah is a peculiar geological formation known as the Qash Delta. Originally a depression, it has been filled with sand and silt brought down by the flash floods of the Qash River, creating a delta above the surrounding plain. Extending 100 kilometers north of Kassala, the whole area watered by the Qash is a rich grassland with bountiful cultivation long after the river has spent its waters on the surface of its delta. Trees and bushes provide grazing for the camels from the north, and the rich moist soil provides an abundance of food crops and cotton. Northward beyond the Qash lie the more formidable Red Sea Hills. Dry, bleak, and cooler than the surrounding land, particularly in the heat of the Sudan summer, they stretch northward into Egypt, a jumbled mass of hills where life is hard and unpredictable for the hardy Beja inhabitants. Below the hills sprawls the coastal plain of the Red Sea, varying in width from about fifty-six kilometers in the south near Tawkar to about twenty-four kilometers near the Egyptian frontier.

The coastal plain is dry and barren. It consists of rocks, and the seaward side is thick with coral reefs. The southern clay plains, which can be regarded as an extension of the northern clay plains, extend all the way from northern Sudan to the mountains on the Sudan-Uganda frontier, and in the west from the borders of Central African Republic eastward to the Ethiopian highlands. This great Nilotic plain is broken by several distinctive features. First, the White Nile bisects the plain and provides large permanent water surfaces such as lakes Fajarial, No, and Shambe. Second, As Sudd, the world's largest swamp, provides a formidable expanse of lakes, lagoons, and aquatic plants, whose area in high flood waters exceeds 30,000 square kilometers, or approximately the size of Belgium. So intractable was this sudd as an obstacle to navigation that a passage was not discovered until the midnineteenth century. Then as now, As Sudd with its extreme rate of evaporation consumes on average more than half the waters that come down the White Nile from the equatorial lakes.

These waters also create a flood plain known as the toic that provides grazing when the flood waters retreat to the permanent swamp and sluggish river, the Bahr al Jabal, as the White Nile is called here. The land rising to the south and west of the southern clay plain is referred to as the Ironstone Plateau (Jabal Hadid), a name derived from its laterite soils and increasing elevation. The plateau rises from the west bank of the Nile, sloping gradually upward to the Congo-Nile watershed. The land is well watered, providing rich cultivation, but the streams and rivers that come down from the watershed divide and erode the land before flowing on to the Nilotic plain flow into in As Sudd. Along the streams of the watershed are the gallery forests, the beginnings of the tropical rain forests that extend far into Zaire. To the east of the Jabal Hadid and the Bahr al Jabal rise the foothills of the mountain ranges along the Sudan-Uganda border--the Imatong, Didinga, and Dongotona--which rise to more than 3,000 meters. These mountains form a stark contrast to the great plains to the north that dominate Sudan's geography.

Nubian Desert | desert, Sudan | Britannica.com Nubian Desert Namib Nubian Desert, Arabic As-ṣaḥrāʾ An-nūbīya, desert in northeastern Sudan . It is separated from the Libyan Desert by the Nile River valley to the west, while to the north is Egypt; eastward, the Red Sea; and southward, the Nile again. Unlike the Libyan Desert, the Nubian Desert is rocky and rugged, though there are some dunes, and toward the Red Sea the desert, rising in gentle slopes to the west, culminates in precipitous uplands of the Red Sea Hills (Jabal Erba 7,273 feet [2,217 m]) to the east. It is essentially a sandstone plateau interspersed with many wadis (seasonal rivers) that die out before reaching the Nile. The rainfall averages less than 5 inches (125 mm) a year. Learn More in these related articles: Corrections? Updates? Help us improve this article! Contact our editors with your feedback. MEDIA FOR: You have successfully emailed this. Error when sending the email. Try again later.

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Close Date Published: July 20, 1998 URL: Access Date: January 19, 2017 Share

Question: What is the name of the eastern part of the Sahara Desert, lying between the Nile and the Red Sea in north-eastern Sudan?
Answer: NUBIAN DESERT