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| − | [[Image:Dune_7_in_the_Namib_Desert.jpeg|250px|thumb|Dune 7, the highest sand dune in the world (ca. 383 m.), in the Namib Desert, Namibia.]]
| + | [[Image:NamibDesert01.jpg|250px|thumb|Sunset at the Namib Rand Nature Reserve, Namibia]] |
| − | [[Image:ConceptionBay Namibia ISS011-E-9756.jpg|thumb|250px|The dune sea of the Namib Desert. Note how the crests of the dunes are aligned in a marked northwest-southeast orientation. These crests form transverse to the formative wind (i.e., crosswise). The dunes act as obstacles, and obstacles cause winds to be deflected significantly to the right, in the southern hemisphere—in effect reorienting the southerly wind as a southwesterly wind.]]
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| − | [[Image:NamibDesert01.jpg|250px|thumb|Sunset at the Namib Rand Nature Reserve, Namibia.]] | |
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| − | The '''Namib Desert''' is a [[desert]] in [[Namibia]] and southwestern [[Angola]] that encompasses the world's highest [[sand dunes]], [[gravel]] plains and rugged [[mountains]]. It stretches some 1,000 miles (1,600 km) along the [[Atlantic Ocean]] coast of Namibia, which is named after this desert. The name "Namib" is from a word in the Nama language that means "immense." The desert occupies an area of around 31,200 m² (80 000 km²), though its east-west width varies from 30 to 100 miles (50-160 km). The area is considered to be the oldest desert in the world, having endured arid or semi-arid conditions for an estimated fifty-five to eighty million years. The Namib is an important location for the mining of [[diamond]]s, [[tungsten]], and [[salt]]. | + | The '''Namib Desert''' is a coastal [[desert]] in [[Namibia]] and southwestern [[Angola]] that encompasses the world's highest [[sand dune]]s, [[gravel]] plains, and rugged [[mountain]]s. It stretches some 1,200 miles (1,900 km) along the [[Atlantic]] coast of Namibia, which is named after this desert. The name "Namib" is from a word in the Nama language that means "immense." The desert occupies an area of around 31,200 m² (80,000 km²), though its east–west width varies from 30 to 100 miles (50–160 km). The area is considered to be the oldest desert in the world, having endured arid or semi-arid conditions for an estimated 55 to 80 million years. The Namib is an important location for the mining of [[diamond]]s, [[tungsten]], and [[salt]]. The diamonds, which are alluvial, are found in beds of gravel. |
| | + | {{toc}} |
| | + | The desert's aridity is caused by the descent of dry, warm air from the east that is cooled by the cold Benguela current along the coast. The upper layer of warm, dry air prevents the cool, humid air from rising and forming clouds. Some areas have less than half an inch (10 mm) of [[rain]] annually and are almost completely barren. |
| | + | [[Image:Dune_7_in_the_Namib_Desert.jpeg|250px|thumb|Dune 7, the highest sand dune in the world (ca. 383 m.), in the Namib Desert, Namibia]] |
| | + | == History == |
| | + | {{readout||left|250px|The Namib Desert, stretching 1,000 miles along the [[Atlantic]] coast of Southern Africa, is believed to be the world's oldest [[desert]] having been arid for at least 55 million years}} |
| | + | The Namib Desert is believed to be the world’s oldest [[desert]] and it has been arid for at least 55 million years. The convergence of the [[Benguela]] upwelling and the hot interior have maintained, and perhaps increased, this aridity in recent times, but they did not generate the aridity. The region, isolated between the [[ocean]] and the [[escarpment]], is considered to be a constant island of aridity surrounded by a sea of climatic change. The arid conditions probably started with the continental split of West [[Gondwana]] 130 million to 145 million years ago when this area shifted to its present position along the [[Tropic of Capricorn]]. This lengthy dry period has had a profound influence on the region’s [[biodiversity]]. The region has remained a relatively stable center for the [[evolution]] of desert [[species]]. This has resulted in a unique array of biodiversity with high levels of endemism and numerous advanced adaptations to arid conditions.<ref> [http://www.worldwildlife.org/wildworld/profiles/terrestrial/at/at1315_full.html Namib desert]. ''World Wildlife Fund.'' Retrieved March 23, 2007. </ref> |
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| − | The desert's [[aridity]] is caused by the descent of dry warm air from the east that is cooled by the cold Benguela current along the coast. The upper layer of cool air prevents the warm air from rising and forming clouds. Some areas have less than half an inch (10 mm) of rain annually and are almost completely barren. | + | ==Flora and fauna== |
| | + | [[Image:Springbok Antelope Namib Desert .jpg|270px|thumb|left| A springbok [[antelope]] in the Namib Desert]] |
| | + | The Namib Desert is home to a number of unusual [[species]] of [[plant]]s and [[animal]]s that are found nowhere else in the world. One of these is ''Welwitschia mirabilis,'' a [[shrub]]-like plant that grows just two long leaves continuously throughout its lifetime. These leaves may grow to be several meters long and over time become gnarled and twisted from the desert winds. They are the longest-lived leaves of any member of the plant kingdom. It is estimated that the largest of these plants are about 2,500 years old. |
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| − | A number of unusual [[species]] of [[plant]]s and [[animal]]s are found only in this desert. One of these is ''Welwitschia mirabilis'', a shrublike plant that grows just two long leaves continuously throughout its lifetime. These leaves may be several meters long, gnarled and twisted from the desert winds. The taproot of the plant develops into a flat, concave disc.
| + | Dense fogs along the coast and the freshwater they contain are the life essence of the Namib. The dew that condenses on desert [[grasses]] and on the bodies of smaller creatures is what sustains many of these animals. Others take advantage of the few muddy water holes, which may draw [[Oryx|gemsbok]], [[ostrich]]es, [[sand grouse]], [[vulture]]s, and [[warthog]]s. |
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| − | Dense [[fog]]s along the coast and the fresh water they contain are the life essence of the Namib. The dew that condenses on desert [[grasses]] and on the bodies of smaller creatures are what sustains many of these animals. Others take advantage of the the few muddy water holes, which may draw gemsbok, ostriches, sand grouse, vultures, and wart hogs.
| + | Most of the animals and plants that survive in the Namib do so by unique adaptations. The gemsbok, for example, also known as the oryx, has a lighter coat than any long-horned [[antelope]] subspecies and an intricate system of [[blood]] vessels and nasal passages that cool its blood before it reaches the [[brain]]. They dig for underground water, drink from watering holes, and feed in the early morning on plants with high moisture content. Its numerous adaptations allow it to tolerate high temperatures and go days without water. |
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| − | Most of the animals and plants that survive in the Namib do so by unique adaptations. The gemsbok, for example, also known as the oryx, has a lighter coat than any long-horned [[antelope]] subspecies and an intricate system of [[blood]] vessels and nasal passages that cool its blood before it reaches the brain. They dig for underground water, drink from watering holes, and feed in the early morning on plants with high moisture content. Its numerous adaptations allow it to tolerate high temperatures and go days without water.
| + | There are almost 70 [[reptile]] species in the ecoregion, of which five are found only in the Namib Desert. The desert is also home to a large number of small [[rodent]] species that occur among the rocky habitats in the western deserts, in the sand dunes, and in the vegetation of the gravel plains. |
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| − | The Namib-Naukluft National Park, one of Africa's largest, contains a huge group of [[sand dune]]s, which at up to 800 ft (300 m) high are the tallest sand dunes in the world. Sossusvlei is a great dry clay marsh (“vlei”). In some years, during the rainy season the waters of the Tsauchab River form pools at the base of the dunes. “Sossus” means “blind river” in the Nama language, so the literary translation of the word Sossusvlei is “marsh of the blind river”, that is “marsh of the river that does not have a mouth toward the sea”.
| + | Namib-Naukluft National Park, one of [[Africa]]'s largest, contains a group of huge [[sand dune]]s, which at nearly a thousand feet (300 meters) high are the tallest sand dunes in the world. During the rainy season in some years, the waters of the Tsauchab River form pools at the base of the dunes. Sossusvlei is a great dry clay marsh (“vlei”). “Sossus” means “blind river” in the Nama language, so the literal translation of the word Sossusvlei is “marsh of the blind river,” that is, “marsh of the river that does not have a mouth toward the sea.” |
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| − | The interaction between the water-laden air coming from the sea via southerly [[wind]]s, some of the strongest of any coastal desert, and the dry air of the desert causes immense fogs and strong currents in which sailors easily lose their way. Along with the Skeleton Coast farther north, the area is notorious as the site of many shipwrecks. Some of these wrecked ships can be found as much as 50 meters inland, as the desert is slowly creeping westward into the sea, reclaiming land over a period of many years. | + | The interaction between the water-laden air coming from the sea via southerly winds, some of the strongest of any coastal desert, and the dry air of the desert causes immense fogs and strong currents in which sailors easily lose their way. Along with the [[Skeleton Coast]] farther north, the area is notorious as the site of many shipwrecks. Some of these wrecked vessels can be found as much as 50 meters inland, as the desert is slowly creeping westward into the sea, reclaiming land over a period of many years. |
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| − | The eastern border in the north and center is the foot of the Great Western Escarpment of Namibia, atop which more humid lands prevail. But in the south, a gradual transition merges the Namib with the Kalahari and Karoo Deserts of the interior. | + | The border of the desert to the north and east is the foot of the Great Western Escarpment of [[Namibia]], atop which more humid lands prevail. But in the south, a gradual transition merges the Namib with the [[Karoo Desert|Karoo]] and [[Kalahari Desert|Kalahari]] deserts of the interior. |
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| − | Climatically, the Namib is a contradictory area: It is almost rainless, yet its air is normally at or near the saturation point, and fog is very common. Temperatures in the coastal area are mild at all seasons, ranging between 58 and 67 degrees F in the warm season (December) and between 46 and 57 degrees F in the cool season (July). Inland, summer temperatures reach the 80s each day and drop into the low 40s on the average winter night. On the coast, humidity is 100 percent for 19 hours per day in summer and for 11 hours in winter. At the inner edge of the desert, the air is much drier, fog is virtually unknown, and the humidity seldom exceeds 50 percent. This is nevertheless fairly high for a desert region. Violent weather is practically unknown; rare thunderstorms bring the precipitation, which averages less than 2 inches annually inland and about one-half inch at the coast.
| + | A curious feature of the Namib Desert is circles on the ground that are accentuated by abrupt changes in the vegetation pattern. These circles, known as "fairy rings," are most noticeable from the air. There has been interest and speculation as to their origin for centuries. It is now thought that they are created by a [[termite]]. |
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| − | Access is via light aircraft from Windhoek (the capital of Namibia, about 480 km east of the center of the desert), Swakopmund and Walvis Bay at the north end of the desert, or overland on gravel roads.
| + | ==Climate== |
| | + | [[Image:ConceptionBay Namibia ISS011-E-9756.jpg|thumb|250px|The dune sea of the Namib Desert. The crests of the dunes are aligned in a marked northwest-southeast orientation. These crests form crosswise to the formative wind. The dunes act as obstacles, and obstacles cause winds to be deflected significantly to the right in the Southern Hemisphere—in effect reorienting the southerly wind as a southwesterly wind.]] |
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| − | == References ==
| + | Climatically, the Namib is a contradictory area: It is almost rainless, yet its air is normally at or near the saturation point, and fog is very common. Temperatures in the coastal area are mild at all seasons, ranging between 58° and 67° F (14° to 20° C) in the warm season (December) and between 46° and 57° F (9° to 14° C) in the cool season (July). Inland, summer temperatures reach the 80s and even over 100° (30 to 45° C) during the day and drop into the low 40s (4 to 7° C) on the average winter night. On the coast, humidity is 100 percent for 19 hours per day in summer and for 11 hours in winter. At the inner edge of the desert, the air is much drier, fog is virtually unknown, and the humidity seldom exceeds 50 percent. This is nevertheless fairly high for a desert region. Violent weather is practically unknown; rare [[thunderstorm]]s bring the precipitation, which averages less than {{convert|2|in}} annually inland and about {{convert|0.5|in}} at the coast. |
| − | * ''Greatest Places'' [http://www.greatestplaces.org/notes/namib.htm], observed March 18, 2007.
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| − | * ''World Wildlife Fund'' [http://www.worldwildlife.org/wildworld/profiles/terrestrial/at/at1315_full.html], observed March 18, 2007.
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| − | * ''National Geographic'', January 1992, pp. 54-85.
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| − | * {{cite web | url=http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17050 | title=Dune Patterns, Namib Desert, Namibia | publisher=[[NASA Earth Observatory]] | accessdate=2006-05-05}}
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| − | * [http://www.acrossthedivide.com/namib.htm Namib Naukluft Park photo gallery]
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| − | * [http://www.travelsaround.eu/eng/namibia/namibdesert/index.html Namib Desert photo gallery]
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| − | {{Category:Deserts}}
| + | ==Threats== |
| − | [[Category:Nations and places]]
| + | A major threat to the Namib Desert is the impact of off-road driving, which is greatest on the gravel plains where depressions left by vehicles remain for more than forty years because the rainfall is too episodic and sparse to erase them. These tracks are unsightly and cause long-lasting damage to the lichen fields. [[Lichen]]s are particularly sensitive to mechanical damage as they grow extremely slowly and cannot quickly repair damaged thalli. Most of the damage is done by mining company vehicles on prospecting expeditions. |
| − | [[Category:Africa]] | |
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| − | {{credit|105519982}}
| + | The major threat to Namib-Naukluft National Park is the drop in the water table along the Kuiseb River, caused primarily by the extraction of [[groundwater]], which supplies the domestic consumption of Walvis Bay and Swakopmund and the enormous demands made by a [[uranium]] [[Mining|mine]] near Swakopmund. At present, the Department of Water Affairs is trying to meet the requirements for water by prospecting for more underground water sources. If water were to be found, roads, pipelines, and power lines would have to be constructed through the most pristine dune desert in the world. The Kuiseb River and the vegetation within it act as a windbreak to the southerly winds, retarding the northward movement of the dune sea onto the gravel plains. The destruction of this natural barrier would have serious ecological consequences in this part of the Namib Desert. Another threat to the Namib-Naukluft Park is the [[Pastoralism|pastoralists]] who graze large herds of [[goat]]s and small groups of [[donkey]]s over the bed of the Kuiseb River and along the edge of the dunes. The livestock have overgrazed the understory plant growth and the fallen acacia seedpods in the riverbed and are competing for food with wild animals, such as gemsboks. |
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| | + | == Notes == |
| | + | <references/> |
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| − | Landforms: The Namib is characterized by several distinct types of landforms: A vast sand sea, monotonously flat plains of gravel and bedrock, mountains of bare rock, and areas with surfaces fretted into strange sandblasted forms. Most of the desert consists of a broad platform, eroded into bedrock of monotonous flatness and rising in a very gradual slope from the coastline to an elevation of some 3,000 feet at the foot of the escarpment. South of the Tropic (of Capricorn), much of this platform is veneered with sand, in the form of sheets, waves, and dunes, the latter sometimes exceeding 800 feet, making them the highest sand dunes in the world. In the southern and central portions, mountains rise about the smooth platform only as isolated individuals and short chains. Most of the mountains are rugged, steep sloped, and almost soilless.
| + | == References == |
| | + | * Barnard, Phoebe. ''Biological Diversity in Namibia: A Country Study.'' Windhoek, Namibia: The Task Force, 1998. ISBN 0869764365 |
| | + | * Bartlett, Des, and Jen Bartlett. “Africa’s Skeleton Coast.” ''National Geographic'' (January 1992): 54–85. |
| | + | * Lovegrove, Barry. ''The Living Deserts of Southern Africa.'' Vlaeberg: Fernwood Press, 1994. ISBN 978-0958315470 |
| | + | * Kinahan, John. ''Pastoral Nomads of the Central Namib Desert: The People History Forgot.'' Windhoek: Namibia Archaeological Trust, 1991. ISBN 9789991631028 |
| | + | * Keen, Cecil. [http://www.greatestplaces.org/notes/namib.htm Greatest Places Physical Geography: Namib] ''Science Museum of Minnesota,'' 1997. Retrieved March 18, 2007. |
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| − | Vegetation : In general, the Namib is a barren waste, with very sparse vegetation. Large areas, notably the gravel flats, the bedrock platform, and the dunes, are almost totally barren. In the zone of heaviest fog near the coast, especially in the south, low succulent bushes grow sporadically. Along the eastern border, a thin to moderate cover of annual grasses appears in most years, supporting for a time a variety of antelopes, zebra, ostrich, and their attendant predators.
| + | ==External links== |
| | + | All links retrieved November 10, 2022. |
| | + | * [http://www.namibian.org/travel/namibia/namib-naukluft.htm Namib Desert] |
| | + | * [http://www.pbs.org/edens/namib/ Namib - Africa's burning shore] ''PBS'' |
| | + | * [http://www.pbs.org/wnet/nature/episodes/the-desert-lions/secrets-of-survival-life-in-the-namib-desert/687/ The Desert Lions, Secrets of Survival: Life in the Namib Desert] ''PBS'' |
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| − | Water Supply : Potable water is found only as sub-flow beneath streambeds chiefly of the larger streams that rise in the rainier plateau east of the escarpment. In some cases, dissolved salts render the water unpleasant. In other cases, such as the Kuiseb and the Koichab, which supply Walvis Bay and Luderitz, the quality is good to excellent.
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| − | Settlements : Walvis Bay has the only harbor on the Namibian coast accessible to deep-water vessels with large freighters and tankers able to come alongside the modern, efficient wharves. Fishing factories line the shore of the bay, each with its own wharf. As the only deep-water railhead in the country, Walvis Bay serves as the principal entry port for the interior. In addition to fish products, exports are chiefly minerals, wool, hides, and pelts destined for all parts of the world. Imports consist chiefly of manufactured goods, petroleum, and foodstuffs. The total population of the town is about 21,000. The water supply to the town is via a pipeline from the Kuiseb River, 23 miles to the southeast, where it is tapped from wells into the underflow of the river. Luderitz is a small-scale replica of Walvis Bay, except that its harbor is not suitable for deep-water vessels. The town's chief role is as the base for the rock lobster or crayfish industry. As a cargo port, its role is minor; its hinterland is poor and is serviced by a rail line and a single graded road. Its population is about 10,000. Its water supply also is from an underflow well mining (of the Koichab River through a 67-mile pipeline across the Namib.
| + | {{Category:Deserts}} |
| | + | {{credit|105519982}} |
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| − | Mining : Diamonds constitute by far the most important mineral product in the territory. The diamonds are alluvial, being found in beds of gravel, usually under a considerable overburden of sterile materials. The large-scale operation of recovery of diamonds is now under one corporation: the Consolidated Diamond Mines (CDM). Because of the high value and light weight of the product and the resultant ease of theft (combined with the difficulty of rescue operations for retrieving "poachers" stranded in this extremely arid region), the entire diamond bearing area and much of its surroundings has been proclaimed a Prohibited Area (Sperrgebiet), totally closed to public entry at all times. The CDM company town of Oranjemund, at the mouth of the Orange River, is the center of diamond mining operations. It is a highly developed, progressive, modern community, with a good water supply from wells near the river and with gardens supplying fresh produce. Offshore dredging operations for the recovery of diamonds from the sea bed have been carried on.
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| − | | + | [[Category:Africa]] |
| − | Other minerals mined in the Namib include zinc (Rosh Pinah mine), tin and wolfram (at Uis and Brandberg Wes). Oil prospecting has been carried out in recent years, but without success.
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| − | Recreation and Tourism : Since the time of German Southwest Africa, the coastal towns of the Namib have always had an attraction to the few and hardy. With the cooler summer climate, the fishing, the relative barrenness of the area, and its historic Germanic flavor have all been attractions for visitors.
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| − | The Namib Desert is believed to be the world’s oldest desert and it has been arid for at least 55 million years (Barnard 1998). The convergence of the Benguela upwelling and the hot interior have maintained, and perhaps increased this aridity in recent times, but they did not generate the aridity. The region, isolated between the ocean and the escarpment, is considered to be a constant island of aridity surrounded by a sea of climatic change (Armstrong 1990). The arid conditions probably started with the continental split of West Gondwana 130 million to 145 million years ago when this area shifted to its present position along the Tropic of Capricorn. This lengthy dry period has had a profound influence on the region’s biodiversity. The region has remained a relatively stable center for the evolution of desert species. This has resulted in a unique array of biodiversity with high levels of endemism and numerous advanced adaptations to arid conditions.
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| − | The monotypic Welwitschia mirabilis, one of the most remarkable plants in the world, is endemic to the Namib Desert and to the Kaokoveld Desert ecoregion to the north. The distribution of this relict gymnosperm extends from the Kuiseb River in Namibia to Namibe in southern Angola (White 1983). These plants are usually found more than 20 m apart, in broad flat channels on gravel plains. The channels are so shallow as to be barely discernable, but receive floodsheet waters from higher areas during the infrequent rains. The soil becomes moist to about 1.5 m and this subsurface moisture can be retained for years. Welwitschia plants are up to 1.5 m tall and have two fibrous, straplike leaves, which persist throughout the entire life of the plant and curl into fantastic shapes on the ground. They are the longest-lived leaves of any member of the plant kingdom. It is estimated that the largest Welwitschia plants are about 2,500 years old (White 1983, Armstrong 1990, Lovegrove 1993).
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| − | In the animals the high species richness and endemism is made up largely of reptiles. They have evolved adaptations to survive in this harsh environment when most birds and large mammals have not. There are almost 70 reptile species in the ecoregion, of which more than 25 are considered endemic to the ecoregion. Five of these are strictly-endemic to the dry Namib Desert, and at least 20 species are regarded as nearly endemic to the ecoregion (WWF database). Several endemic reptiles, including two desert lizards, the wedge-snouted sand lizard (Meroles cuneirostris) and the small-scaled sand lizard (M. micropholidotus), the barking gecko (Ptenopus kochi) and the day gecko (Rhoptropus bradfieldi) are unusual in that they all dive beneath the sand to escape danger (Branch 1998).
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| − | The Namib Desert is home to a large number of small rodent species that occur among the rocky habitats in the western deserts, in the sand dunes and in the vegetation of the gravel plains. The gerbil, Gerbillurus tytonis is restricted to the southern portion of the ecoregion (WWF database). Grant’s golden mole (Eremitalpa granti VU) is near-endemic in the Namib Desert, its range extending down into South Africa. This eyeless mole is well-adapted to the desert, able to swim through the loose, dry sands of the Namib dunes. The Namaqua dune molerat (Bathyergus janetta LR) is also near-endemic in the Namib Desert, as are two bat species; the Namib long-eared bat (Laephotis namibensis EN) and the Angola wing-gland bat (Myotis seabrai VU) (Hilton-Taylor 2000).
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| − | Larger ungulates are scarce in the Namib Desert, with only gemsbok (Oryx gazella LR) and springbok (Antidorcas marsupialis LR) present (Griffin 1998). Hartmann’s zebra (Equus zebra hartmannae EN) is found in the extreme east of the desert, in the transition belt between the desert and the escarpment. However, they do move further into the desert along vegetated riverbeds (Joubert and Mostert 1975). Gemsbok are the most widespread ungulates in the desert habitat and can survive for weeks without drinking by ceasing to sweat when deprived of water. At such times, their body temperature may reach as high as 45°C, and can be sustained at this level through the heat of the day by a network of fine blood vessels at the base of the brain that exchanges heat to prevent brain damage (Armstrong 1990). The predators of the Namib Desert are cheetahs (Acinonyx jubatus, VU), brown hyenas (Hyaena brunnea, LR) and spotted hyenas (Crocuta crocuta), Cape foxes (Vulpes chama) and bat-eared foxes (Otocyon megalotis). Brown hyenas are common around Luderitz, and this area supports the highest density of this species in Namibia (Pallett 1995). Klipspringers (Oreotragus oreotragus), steenboks (Raphicerus campestris), baboons (Papio ursinus) and leopards (Panthera pardus) occur along the courses of the Kuiseb and Swakop Rivers (Lovegrove 1993). Many species have become locally extinct in the southern areas of the Namib Desert. Lions (Panthera leo), elephants (Loxodonta africana), black rhinos (Diceros bicornis), white rhinos (Ceratotherium simum), giraffes (Giraffa camelopardalis) and hippos (Hippopotamus amphibius) were all shot out by colonial settlers who established themselves along the Orange River. The lower Orange River was once famous for its large numbers of hippos, which came onshore to graze on the floodplains at night (Pallett 1995).
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| − | The desert does not have a very high level of avian richness, with only 180 species recorded to date. This is due to the extremely arid terrain and a lack of rivers, with even ephemeral rivers absent in the southern part. The most prominent bird found in the desert is the ostrich (Struthio camelus). Most of the bird life is concentrated along the coastline. The isolated Sandvis area (previously known as Sandwich Harbor) situated on the coast at about 23°S is an area of high species richness. To date, the number of species recorded at Sandvis is 113 and represents a wide taxonomic variety (Berry and Berry 1975). Six birds are considered endemic to the Namib Desert: the dune lark (Certhilauda erythrochalamys), Benguela long-billed lark (C. benguelensis) (Ryan et al. 1999), Gray’s lark (Ammomanes grayi), bank cormorant (Phalacrocorax neglectus), tractrac chat (Cercomela tractrac), and Rüppell’s korhaan (Eupodotis rueppellii). The dune lark is strictly endemic to this ecoregion while the gray’s lark, Rüppell’s korhaan, and C. benguelensis are found only in this ecoregion and the Kaokoveld Desert ecoregion.
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| − | The Namib Desert is best known for its high species richness of beetles, particularly those belonging to the family Tenebrionidae (Lovegrove 1993). Many of these have evolved methods of condensing fog as a source of water. The head-standing beetle (Onymacris unguicularis) for example, creeps to the crest of a dune when fog is present. It then faces into the wind and stretches its back legs so that its body tilts forward, head down. As fog precipitates onto its body and runs down into its mouth the beetle drinks (Armstrong 1990).
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| − | A curious feature of the Namib Desert is circles on the ground that are accentuated by abrupt changes in the vegetation pattern. These circles, known as "fairy rings" are most noticeable from the air. They occur on the eastern fringes of the desert from southern Angola all the way through this ecoregion, characteristically within the Stipagrostis grassland community. The origin of these circles has generated interest and speculation for centuries (Lovegrove 1993). Various hypotheses have been advanced for their formation, from geomorphological phenomena, to plants having allelopathic exclusion effects, to being animal derived features. A similar phenomenon occurs to the south of the Orange River in the form of heuweltjies (originally termitaria) that are about 30 m in diameter and 1 m high. Recent evidence has shown that the harvester termite Microhodotermes viator most likely creates these heuweltjies. It is now thought that the fairy rings of the Namib Desert are created through a similar process by one of three possible termite species: Hodotermes mossambicus, Psammotermes allocerus, or Baucaliotermes hainsei (Moll 1994).
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| − | Current Status
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| − | The present conservation status of the Namib Desert is good as most of the ecoregion is intact and is protected in extensive conservation blocks (Maggs et al. 1998). The Namib-Naukluft National Park (49,768 km2) is the largest conservation area in southern Africa and protects the central area of this ecoregion. The park runs from Swakopmund in the north to Luderitz in the south. The southern part of the park is taken up by the large expanse known as Diamond Area No. 2, to which public entry is strictly prohibited. The park covers gravel plains, the dune sea, the eastern semi-desert and the Kuiseb River and is therefore a good representation of the Central and Southern Namib vegetations (du Plessis 1992). The well-known Soussusvlei is located within this park and is surrounded by the highest sand dunes in the world. The vlei itself is a large shallow hollow that fills with water during the infrequent rains (Stuart and Stuart 1992).
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| − | To the north of the Namib-Naukluft National Park lies the National West Coast Tourist Recreation Area. This area extends for 180 km up the coast and is under less stringent protection than the national parks. The Cape Cross Seal Reserve is located within this area and protects one of the largest colonies of Cape fur seals (Arctocephalus pusillus) in southern Africa. Between 80,000 and 100,000 seals live on the rocks here.
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| − | Types and Severity of Threats
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| − | A major threat to the Namib Desert is the impact of off-road driving. The impact is the greatest on the gravel plains where depressions left by vehicles remain for more than 40 years because the rainfall is too episodic and sparse to erase them. These tracks are unsightly and cause long-lasting damage to the lichen fields. Lichens are particularlysensitive to mechanical damage as they grow extremely slowly and cannot quickly repair damaged thalli. Most of the damage is done by mining company vehicles when on prospecting expeditions (Lovegrove 1993).
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| − | The major threat to the Namib-Naukluft National Park is the drop in the water table along the Kuiseb River. This is caused primarily by the extraction of ground water by the Department of Water Affairs at two sites near Walvis Bay (Lovegrove 1993). The extracted water supplies the domestic consumption of Walvis Bay and Swakopmund and the enormous demands made by the Rossing Uranium Mine near Swakopmund. At present, the Department of Water Affairs is trying to meet the requirements for water by prospecting for more underground water sources. If water were to be found, roads, pipelines and powerlines would have to be constructed through the most pristine dune desert in the world (Lovegrove 1993). The Kuiseb River and the vegetation within it acts as a windbreak to the southerly winds, retarding the northwards movement of the dune sea onto the gravel plains. The destruction of this natural barrier would have serious ecological consequences in this part of the Namib Desert (Lovegrove 1993). Another threat to the Namib-Naukluft Park is the Topnaar pastoralists who graze large herds of goats and small groups of donkeys over the Kuiseb Riverbed and along the edge of the dunes. The livestock have overgrazed the understory plant growth and fallen Acacia seedpods of the riverbed and are competing for food with wild animals, such as gemsboks.
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| − | Collectors of succulent plant species are also having an impact on the flora to the south of the ecoregion. Illegal trade in species such as the halfmens Pachypodium namaquanum is thought to be considerable (Maggs et al. 1998).
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| − | Justification of Ecoregion Delineation
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| − | The Namib Desert is nested within the ‘Namib’ biogeographical province of Udvardy (1975) and the ‘Namib Desert’ unit of White (1983), with the eastern boundary taken from the 100 mm rainfall isohyet. The northern limit is at the Huab River, which a geographic boundary (Giess 1971) between the summer rainfall (northern) and winter rainfall (southern) deserts along this coastline. The southern portion of White’s ‘Namib Desert’ unit, although referred to as the southern Namib, shares affinities with the Succulent Karoo. Thus, the portion south of Luderitz, Namibia was appended to the Succulent Karoo ecoregion.
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| − | References
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| − | Armstrong, S. 1990. Fog, wind and heat: life in the Namib desert. New Scientist, vol 127. 14 July: 46 - 50.
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| − | Barnard, P., editor. 1998. Biological Diversity in Namibia. Namibian National Biodiversity Task Force, Directorate of Environmental Affairs, Windhoek.
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| − | Barnard, P., C.J. Brown, A.M. Jarvis, and A. Robertson. 1998. Extending the Namibian protected areas network to safeguard hotspots of endemism and diversity. Biodiversity and Conservation 7: 531-547.
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| − | Berry, H.H., and C.U. Berry. 1975. A checklist and notes on the birds of Sandvis, South West Africa. Madoqua 9(2): 5-18.
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| − | Branch, B. 1998. Field guide to the snakes and other reptiles of southern Africa. Struik, Cape Town.
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| − | Du Plessis, W. 1992. In situ conservation in Namibia: the role of national parks and nature reserves. Dintera 23: 132-141.
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| − | Giess, W. 1971. A preliminary vegetation map of South West Africa. Dintera 4: 1-114.
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| − | Griffin, M. 1998. The species diversity, distribution and conservation of Namibian mammals. Biodiversity and Conservation 7: 483-494.
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| − | Hilton-Taylor, C. 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, United Kingdom.
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| − | Jacobson, P.J., K.M. Jacobson, and M.K. Seely. 1995. Ephemeral rivers and their catchments: sustaining people and development in western Namibia. Desert Research Foundation of Namibia, Windhoek.
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| − | Joubert, E., and P. K. N. Mostert. 1975. Distribution patterns and status of mammals in South West Africa. Madoqua 9(1): 8-22.
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| − | Lovegrove, B. 1993. The Living Deserts of Southern Africa. Fernwood Press, Vlaeberg
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| − | Maggs, G.L., H.H. Kolberg, and C.J.H. Hines. 1994. Botanical diversity in Namibia – an overview. Pages 93 – 104 in B.J. Huntley, editor. Botanical Diversity in Southern Africa: Strelitzia, Vol 1.
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| − | Maggs, G.L., P. Craven, and H.H. Kolberg. 1998. Plant species richness, endemism, and genetic resources in Namibia. Biodiversity and Conservation 7: 435-446.
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| − | Moll, E.J. 1994. The origin and disribution of fairy rings in Namibia. Pages 1203-1209 in Proceedings of the XIIIth Plenery Meeting of AETFAT, Malawi.
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| − | Pallett, J., editor. 1995. The Sperrgebiet: Namibia’s least known wilderness. An environmental profile of the Sperrgebiet or Diamond Area 1, in southwestern Namibia. DRFN and NAMDEB, Windhoek, 84 pp.
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| − | Ryan, P.G., I. Hood, P. Bloomer, J. Komen and T. Crowe 1999. Barlow's Lark: a new species in the Karoo Lark Certhilauda albescens complex. Ibis 140: 605-619.
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| − | Stuart, C., and T. Stuart. 1992. Guide to Southern African Game and Nature Reserves. Struik, Cape Town.
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| − | Udvardy, M.D.F. A classification of the biogeographical provinces of the world. IUCN Occasional Paper No. 18 (International Union of Conservation of Nature and Natural Resources, Morges, Switzerland, 1975).
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| − | Von Willert, D.J., B.M. Eller, M.J.A. Werger, E. Brinckmann, and H.D. Ihlenfeldt. 1992. Life Strategies of Succulents in Deserts. Cambridge University Press.
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| − | Werger, M.J.A. 1978. Biogeography and Ecology of Southern Africa. Junk, The Hague.
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| − | Wessels, D.C.J. 1989. Lichens of the Namib Desert, Namibia. Dintera 20: 3-28.
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| − | White, F. 1983. The vegetation of Africa, a descriptive memoir to accompany the UNESCO/AETFAT/UNSO Vegetation Map of Africa (3 Plates, Northwestern Africa, Northeastern Africa, and Southern Africa, 1:5,000,000). UNESCO, Paris.
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| − | Williamson, G. 1997. Preliminary account of the floristic zones of the Sperregebiet (Protected Diamond Area) in southwest Namibia. Dintera 25: 1-68.
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| − | Prepared by: Amy Spriggs
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| − | Reviewed by: In progress
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| − | For more general information on this ecoregion, go to the WildWorld version of this description.
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Sunset at the Namib Rand Nature Reserve, Namibia
The Namib Desert is a coastal desert in Namibia and southwestern Angola that encompasses the world's highest sand dunes, gravel plains, and rugged mountains. It stretches some 1,200 miles (1,900 km) along the Atlantic coast of Namibia, which is named after this desert. The name "Namib" is from a word in the Nama language that means "immense." The desert occupies an area of around 31,200 m² (80,000 km²), though its east–west width varies from 30 to 100 miles (50–160 km). The area is considered to be the oldest desert in the world, having endured arid or semi-arid conditions for an estimated 55 to 80 million years. The Namib is an important location for the mining of diamonds, tungsten, and salt. The diamonds, which are alluvial, are found in beds of gravel.
The desert's aridity is caused by the descent of dry, warm air from the east that is cooled by the cold Benguela current along the coast. The upper layer of warm, dry air prevents the cool, humid air from rising and forming clouds. Some areas have less than half an inch (10 mm) of rain annually and are almost completely barren.
Dune 7, the highest sand dune in the world (ca. 383 m.), in the Namib Desert, Namibia
History
Did you know?
The Namib Desert, stretching 1,000 miles along the
Atlantic coast of Southern Africa, is believed to be the world's oldest
desert having been arid for at least 55 million years
The Namib Desert is believed to be the world’s oldest desert and it has been arid for at least 55 million years. The convergence of the Benguela upwelling and the hot interior have maintained, and perhaps increased, this aridity in recent times, but they did not generate the aridity. The region, isolated between the ocean and the escarpment, is considered to be a constant island of aridity surrounded by a sea of climatic change. The arid conditions probably started with the continental split of West Gondwana 130 million to 145 million years ago when this area shifted to its present position along the Tropic of Capricorn. This lengthy dry period has had a profound influence on the region’s biodiversity. The region has remained a relatively stable center for the evolution of desert species. This has resulted in a unique array of biodiversity with high levels of endemism and numerous advanced adaptations to arid conditions.[1]
Flora and fauna
A springbok
antelope in the Namib Desert
The Namib Desert is home to a number of unusual species of plants and animals that are found nowhere else in the world. One of these is Welwitschia mirabilis, a shrub-like plant that grows just two long leaves continuously throughout its lifetime. These leaves may grow to be several meters long and over time become gnarled and twisted from the desert winds. They are the longest-lived leaves of any member of the plant kingdom. It is estimated that the largest of these plants are about 2,500 years old.
Dense fogs along the coast and the freshwater they contain are the life essence of the Namib. The dew that condenses on desert grasses and on the bodies of smaller creatures is what sustains many of these animals. Others take advantage of the few muddy water holes, which may draw gemsbok, ostriches, sand grouse, vultures, and warthogs.
Most of the animals and plants that survive in the Namib do so by unique adaptations. The gemsbok, for example, also known as the oryx, has a lighter coat than any long-horned antelope subspecies and an intricate system of blood vessels and nasal passages that cool its blood before it reaches the brain. They dig for underground water, drink from watering holes, and feed in the early morning on plants with high moisture content. Its numerous adaptations allow it to tolerate high temperatures and go days without water.
There are almost 70 reptile species in the ecoregion, of which five are found only in the Namib Desert. The desert is also home to a large number of small rodent species that occur among the rocky habitats in the western deserts, in the sand dunes, and in the vegetation of the gravel plains.
Namib-Naukluft National Park, one of Africa's largest, contains a group of huge sand dunes, which at nearly a thousand feet (300 meters) high are the tallest sand dunes in the world. During the rainy season in some years, the waters of the Tsauchab River form pools at the base of the dunes. Sossusvlei is a great dry clay marsh (“vlei”). “Sossus” means “blind river” in the Nama language, so the literal translation of the word Sossusvlei is “marsh of the blind river,” that is, “marsh of the river that does not have a mouth toward the sea.”
The interaction between the water-laden air coming from the sea via southerly winds, some of the strongest of any coastal desert, and the dry air of the desert causes immense fogs and strong currents in which sailors easily lose their way. Along with the Skeleton Coast farther north, the area is notorious as the site of many shipwrecks. Some of these wrecked vessels can be found as much as 50 meters inland, as the desert is slowly creeping westward into the sea, reclaiming land over a period of many years.
The border of the desert to the north and east is the foot of the Great Western Escarpment of Namibia, atop which more humid lands prevail. But in the south, a gradual transition merges the Namib with the Karoo and Kalahari deserts of the interior.
A curious feature of the Namib Desert is circles on the ground that are accentuated by abrupt changes in the vegetation pattern. These circles, known as "fairy rings," are most noticeable from the air. There has been interest and speculation as to their origin for centuries. It is now thought that they are created by a termite.
Climate
The dune sea of the Namib Desert. The crests of the dunes are aligned in a marked northwest-southeast orientation. These crests form crosswise to the formative wind. The dunes act as obstacles, and obstacles cause winds to be deflected significantly to the right in the Southern Hemisphere—in effect reorienting the southerly wind as a southwesterly wind.
Climatically, the Namib is a contradictory area: It is almost rainless, yet its air is normally at or near the saturation point, and fog is very common. Temperatures in the coastal area are mild at all seasons, ranging between 58° and 67° F (14° to 20° C) in the warm season (December) and between 46° and 57° F (9° to 14° C) in the cool season (July). Inland, summer temperatures reach the 80s and even over 100° (30 to 45° C) during the day and drop into the low 40s (4 to 7° C) on the average winter night. On the coast, humidity is 100 percent for 19 hours per day in summer and for 11 hours in winter. At the inner edge of the desert, the air is much drier, fog is virtually unknown, and the humidity seldom exceeds 50 percent. This is nevertheless fairly high for a desert region. Violent weather is practically unknown; rare thunderstorms bring the precipitation, which averages less than 2 inches (51 mm) annually inland and about 0.5 inches (13 mm) at the coast.
Threats
A major threat to the Namib Desert is the impact of off-road driving, which is greatest on the gravel plains where depressions left by vehicles remain for more than forty years because the rainfall is too episodic and sparse to erase them. These tracks are unsightly and cause long-lasting damage to the lichen fields. Lichens are particularly sensitive to mechanical damage as they grow extremely slowly and cannot quickly repair damaged thalli. Most of the damage is done by mining company vehicles on prospecting expeditions.
The major threat to Namib-Naukluft National Park is the drop in the water table along the Kuiseb River, caused primarily by the extraction of groundwater, which supplies the domestic consumption of Walvis Bay and Swakopmund and the enormous demands made by a uranium mine near Swakopmund. At present, the Department of Water Affairs is trying to meet the requirements for water by prospecting for more underground water sources. If water were to be found, roads, pipelines, and power lines would have to be constructed through the most pristine dune desert in the world. The Kuiseb River and the vegetation within it act as a windbreak to the southerly winds, retarding the northward movement of the dune sea onto the gravel plains. The destruction of this natural barrier would have serious ecological consequences in this part of the Namib Desert. Another threat to the Namib-Naukluft Park is the pastoralists who graze large herds of goats and small groups of donkeys over the bed of the Kuiseb River and along the edge of the dunes. The livestock have overgrazed the understory plant growth and the fallen acacia seedpods in the riverbed and are competing for food with wild animals, such as gemsboks.
Notes
References
ISBN links support NWE through referral fees
- Barnard, Phoebe. Biological Diversity in Namibia: A Country Study. Windhoek, Namibia: The Task Force, 1998. ISBN 0869764365
- Bartlett, Des, and Jen Bartlett. “Africa’s Skeleton Coast.” National Geographic (January 1992): 54–85.
- Lovegrove, Barry. The Living Deserts of Southern Africa. Vlaeberg: Fernwood Press, 1994. ISBN 978-0958315470
- Kinahan, John. Pastoral Nomads of the Central Namib Desert: The People History Forgot. Windhoek: Namibia Archaeological Trust, 1991. ISBN 9789991631028
- Keen, Cecil. Greatest Places Physical Geography: Namib Science Museum of Minnesota, 1997. Retrieved March 18, 2007.
External links
All links retrieved November 10, 2022.
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