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The Makgadikgadi Pan is a large salt pan in the middle of the dry savanna of north-eastern Botswana, it is one of the largest salt flats in the world.
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Location and description
Lying southeast of the Okavango Delta and surrounded by the Kalahari desert Makgadikgadi is technically not a single pan but many pans with sandy desert in between, the largest being the Sua (Sowa), Ntwetwe and Nxai Pans. The largest individual pan is about 5,000 km2 (1,930.5 sq mi). A dry salty clay crust most of the year the pans are seasonally covered with water and grass, and are then a refuge for birds and animals in this very arid part of the world. The climate is hot and dry but with regular annual rains.
The main water source is the Nata River, called Amanzanyama in Zimbabwe where it rises at Sandown about 60 km (37.3 mi) from Bulawayo. A smaller amount of water is supplied by the Boteti River from the Okavango delta.
These salt pans cover 16,000 km2 (6,177.6 sq mi) in the Kalahari basin and form the bed of the ancient Lake Makgadikgadi that started evaporating many millennia ago. Archaeological recovery in the Makgadikgadi has revealed the presence of prehistoric man through abundant finds of stone tools; some of these tools have been dated sufficiently early to establish their origin as earlier than the era of Homo sapiens.[1] Pastoralists herded grazing livestock here when water was more plentiful earlier in the Holocene.[2]
By way of comparison, Salar de Uyuni in Bolivia is a single salt flat of 10,582 km2 (4,085.7 sq mi), rarely has much water, and is generally claimed to be the world's largest salt pan. The lowest place in the basin is Sua Pan with an elevation of 890 m.[3]
Geology
As the ancestral Lake Makgadikgadi shrank, it left relict shorelines which are most evident in the southwestern part of the basin.[3] As the lake shrank numerous smaller lakes formed with progressively smaller shorelines. The relict shoreline at +945 m. and the one at +920 m. can be seen mostly easily on Gidikwe Ridge, west of the Boteti River.[3]
The geologic reasons for the creation of the basin are not well understood. It is conjectured that a there is a gentle down-warping of the crust with accompanying mild tectonics and associated faulting; however, no significant plate boundary faults have been identified.[3][4] The main axis of the developing graben runs northeast-southwest.[5]
Kubu Island and Kukome Island are igneous rock "islands" in the salt flat of Sua pan.[6] Kubu Island lies in the southwestern quadrant of Sua Pan, contains a number of baobab trees, and is protected as a national monument.[7]
Flora
The pans themselves are salty desert whose only plant life is a thin layer of blue-green algae. However the fringes of the pan are salt marshes and further out these are circled by grassland and then shrubby savanna. The prominent baobab trees found in the area function as local landmarks.
Fauna
Very little wildlife can exist here during the harsh dry season of strong hot winds and only salt water but following a rain the pan becomes an important habitat for migrating animals including wildebeest and one of Africa's biggest zebra populations, and the large predators that prey on them. The wet season also brings migratory birds such as ducks, geese and White Pelicans. The pan is home to the only breeding population of Greater Flamingos in southern Africa. The only birds here in the dry season are ostriches, Chestnut-banded Plover (Charadrius pallidus) and Kittlitz’s Plover (Charadrius pecuarius). The grasslands on the fringes of the pan are home to reptiles such as tortoises, rock monitor (Varanus albigularis), snakes and lizards including the endemic Makgadikgadi spiny agama (Agama hispida makgadikgadiensis).
Threats and preservation
The slat pans are very inhospitable and human intervention has been minimal so they remain fairly undisturbed, although land surrounding the pans is used for grazing and some areas have been fenced off preventing the migration of wildlife. Modern commercial operations to extract salt and soda ash began on Sua Pan in 1991 and there are also plans to divert water from the Nata River for irrigation, which would cause severe damage to the salt pan ecosystem. Another threat is tourism using quad bikes and off-road vehicles, which disturb breeding colonies of penguins and flamingos. Illegal hunting in the national parks is a persistent problem.
There are some protected areas within the Makgadikgadi and Nxai Pan National Park. The Makgadikgadi Pans Game Reserve is the scene of large migrations of zebra and wildebeest from the Boteti River across to Ntwetwe Pan, while the Nata Sanctuary in Sua Pan is a place to see birdlife and antelopes. In Nxai Pan you can still see the baobabs painted by 19th century British artist Thomas Baines. The area can be accessed between the towns of Nata and Maun or from the town of Gweta.
Top Gear - the first crossing by car
The Makgadikgadi was first crossed in a car in a 2007 episode by the presenters of British TV show Top Gear - Jeremy Clarkson, Richard Hammond and James May, as part of a challenge to cross Botswana in second-hand two wheel drive cars, not made for off-road, bought for under £1500. (Clarkson had previously crossed the Makgadikgadi using a quad bike.)[8]
All three cars made it through the Makgadikgadi, although Clarkson and May had to reduce the weight of the cars (a Lancia Beta and Mercedes-Benz 230E respectively), as heavy vehicles tend to sink through the salty surface into the mud below, by removing seats, doors, windows and other bodywork - but were still too heavy and frequently broke through the crust of the salt pan, bogging down. Hammond's unmodified 1963 Opel Kadett, nicknamed 'Oliver', skittered across the surface, never losing traction. A Volkswagen Beetle was also driven unmodified across the salt flats, as a backup car in case one of the other 3 cars would break down.[9]
See also
References
- ^ C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham [1]
- ^ Chris McIntyre (2008) Botswana: Okavango Delta, Chobe, Northern Kalahari, Bradt publishers, 502 pages ISBN 1841621668
- ^ a b c d Helgren, David M. (1984) "Historical Geomorphology and Geoarchaeology in the Southwestern Makgadikgadi Basin, Botswana" Annals of the Association of American Geographers 74(2): pp. 298-307, page 299
- ^ Cooke, H. J. (1980) "Landform evolution in the context of climatic change and neo-tectonism in the Middle Kalahari of north-central Botswana" Transactions, Institute of British Geographers 5: pp. 80-99, pages 83-84
- ^ Cooke, H. J. (1980) "Landform evolution in the context of climatic change and neo-tectonism in the Middle Kalahari of north-central Botswana" Transactions, Institute of British Geographers 5: pp. 80-99, page 85
- ^ McIntyre, Chris (2007) Botswana: Okavango Delta, Chobe, Northern Kalahari: the Bradt Safari Guide (2nd edition) Bradt, Chalfont, St. Peter, England, page 381, ISBN 978-1-84162-166-1
- ^ Hardy, Paula and Firestone, Matthew D. (2007) Botswana & Namibia Lonely Planet, Footscray, Victoria, Australia, page 100, ISBN 978-1-74104-760-8
- ^ "Clarkson's incredible journey, Top Gear magazine". 2006-11-02. http://www.topgear.com/content/features/stories/2006/11/stories/02/1.html.
- ^ "Season 10, Episode 4". Top Gear. BBC. 2007-11-04.
External links
Coordinates: 20°43′0″S 24°57′3″E / 20.716667°S 24.95083°E
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