Drakensberg

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Drakensberg
Maluti, uKhahlamba
Highest point
Peak Thabana Ntlenyana
Elevation 3,482 m (11,424 ft)
Coordinates 29°28′S 29°16′E / 29.467°S 29.267°E / -29.467; 29.267Coordinates: 29°28′S 29°16′E / 29.467°S 29.267°E / -29.467; 29.267
Dimensions
Length 1,000 km (620 mi) SW to NE
Naming
Etymology Dragon's mountain
Geography
Countries South Africa and Lesotho
Type of rock Basalt and Sandstone

The Drakensberg (derived from the Afrikaans name Drakensberge meaning "Dragon Mountains") is the name given to the eastern portion of the Great Escarpment, which encloses the central Southern African plateau. The Great Escarpment reaches its greatest altitude in this region (2000 – 3000 m), and is at its most majestic in appearance. From below, this part of the escarpment has the appearance of a range of mountains, hence its name, “Dragon Mountains” in Afrikaans.

A map of South Africa showing the central plateau edged by the Great Escarpment and its relationship to the Highveld and Lesotho Highlands. The portion of the Great Escarpment shown in red is known as the Drakensberg, although most South Africans think of the Drakensberg as only that portion of the Escarpment which forms the border between KwaZulu-Natal and Lesotho. Here the Escarpment rises to its greatest height of over 3000 m.

The Drakensberg escarpment stretches for over 1000 km from the Eastern Cape Province in the south, then successively forming, in order from south to north, the border between Lesotho and the Eastern Cape, and the border between Lesotho and KwaZulu-Natal Province. Thereafter it forms the border between KwaZulu-Natal and the Free State, followed by the border between KwaZulu-Natal and Mpumalanga Province. It then courses through Mpumalanga to end near Tzaneen in Limpopo Province.[1]

Geological origins

About 180 million years ago a mantle plume under southern Gondwana caused bulging of the continental crust in the area that would later became southern Africa.[2] Within 10 – 20 millions rift valleys formed on either side of the central bulge, which became flooded to become the proto-Atlantic and proto-Indian Oceans.[3][4] The stepped steep walls of these rift valleys formed escarpments that surrounded the newly formed Southern African subcontinent.[2]

With the widening of the Atlantic, Indian and Southern Oceans, Southern Africa became tectonically quiescent. Earthquakes rarely occur, and there has been no volcanic or orogenic activity for about 50 million years.[5] This resulted in an almost uninterrupted period of erosion, continuing to the present, which shaved off a 1–2 km thick layer from the surface of the plateau.[2] A thick layer of marine sediment was consequently deposited onto the continental shelf (the lower steps of the original rift valley walls) which surrounds the subcontinent.[6]

During the past 20 million years, Southern Africa has experienced further massive uplifting, especially in the east, with the result that most of the plateau, despite the extensive erosion, lies above 1000 m, tilted so that it is at its highest in the east, sloping gently downwards towards the west and south. Thus the altitude of the edge of the eastern escarpments is typically in excess of 2000 m. It reaches its highest point (over 3000 m) where the escarpment forms the Lesotho - KwaZulu-Natal international border.[7][8]

The uplifting of the central plateau during the past 20 million years, caused the original escarpment to be moved inland through erosion to its present position.[7][9] The position of the present escarpment is therefore well inland of the original fault lines which formed the walls of the rift valleys that developed during the break-up of Gondwana.

Because of the extensive erosion of the plateau itself, during most of the Mesozoic and Cenozoic eras, none of its surface rocks (except the Kalahari sands) are younger than 180 million years.[10][11] The youngest rocks that remain cap the plateau in Lesotho. These are the Clarens Formation laid down under desert conditions about 200 million years ago, topped by a 1600 m thick layer of lava which erupted, and covered most of Southern Africa, and indeed large parts of Gondwana, about 180 million years ago.[12][13][14] These rocks form the steep sides of the Great Escarpment in this region, where its upper edge reaches an altitude in excess of 3000 m.

The surface below the escarpment has, in general, eroded more than the plateau, so that rocks more than 3000 million years old are found in the Mpumalanga Lowveld below the Mpumalanga portion of the Great Escarpment.[11]

The entire eastern portion of the Great Escarpment (see the accompanying map) constitutes the Drakensberg[8][15] (meaning “Dragon Mountains” in Afrikaans), because of the escarpment’s appearance from below. The Drakensberg terminate in the north near Tzaneen at about the 22° S parallel. The absence of the Great Escarpment for about 450 km (280 miles) to the north of Tzaneen (to reappear on the border between Zimbabwe and Mozambique in the Chimanimani Highlands), is due to a failed westerly branch of the main rift that caused Antarctica to start drifting away from Southern Africa during the break up of Gondwana about 150 million years ago. The lower Limpopo River and Rio Save drain into the Indian Ocean through what remains of this relict incipient rift valley, which now forms part of the South African Lowveld.[9]

Most South Africans, and visitors, however, when they speak of the Drakensberg, refer to the Great Escarpment that forms the border between Lesotho and KwaZulu-Natal, believing it to be a range of mountains extending into Lesotho, more correctly known as the Lesotho Highlands. This portion of the Drakensberg is known as uKhahlamba ("Barrier of Spears") in Zulu and Maluti in Sotho. Geologically this part of the Drakensberg resembles the Simien Mountains of Ethiopia.

Geomorphology

Appearance

The escarpment seen from below looks like a range of mountains. The Limpopo, Mpumalanga and Lesotho Drakensberg have hard erosion resistant upper surfaces and therefore have a very rugged appearance, combining steep-sided blocks and pinnacles (reminiscent of Dragon's teeth, hence the name "Drakensberg'). The KwaZulu-Natal - Free State Drakensberg are composed of softer rocks and therefore have a more rounded, softer appearance from below. The top of the escarpment is generally almost table-top flat and smooth, even in Lesotho. The "Lesotho Mountains" are formed away from the Drakensberg escarpment by erosion gulleys which turn into deep valleys which contain the tributaries that flow into the Orange river. There are so many of these tributaries that it gives the Lesotho Highlands a very rugged mountainous appearance, both from the ground and from the air.

Composition

The geological composition of Drakensberg (escarpment wall) varies considerably along its more than 1000 km length. The Limpopo and Mpumalanga Drakensberg are capped by an erosion resistant quartzite layer which is part of the Transvaal Supergroup which also forms the Magaliesberg to the north and northwest of Pretoria.[16] These rocks are more than 2000 million years old. South of the 26°S parallel the Drakensberg escarpment is composed of Ecca shales, which belong to the Karoo Supergroup, which are 300 million years old.[11][17] The portion of the Drakensberg that forms the KwaZulu-Natal – Free State border is formed by slightly younger Beaufort rocks (250 million years old) which are also part of the Karoo Supergroup. The Ecca and Beaufort groups are composed of sedimentary rocks which are less erosion resistant than the other rocks which make up the Drakensberg escarpment. This portion of escarpment is therefore not as impressive as the Mpumalanga and Lesotho stretches of the Drakensberg. The Drakensberg which form the north-eastern and eastern borders of Lesotho, as well as the Eastern Cape Drakensberg are composed of a thick layer of basalt (lava) which erupted 180 million years ago.[12][11] That rests on the youngest of the Karoo Supergroup sediments, the Clarens sandstone, which was laid down under desert conditions, about 200 million years ago.[12][11]

Highest peaks

The highest peak is Thabana Ntlenyana, at 3,482 metres (11,424 ft). Other notable peaks include Mafadi (3,450 m or 11,319 ft), Makoaneng at 3,416 m, Njesuthi at 3,408 m, Champagne Castle at 3,377 m, Giant's Castle at 3,315 m, Ben Macdhui at 3,001 m, and Popple Peak at 3331m, all of these are in the area bordering on Lesotho. Another popular area for hikers is Cathedral Peak. North of Lesotho the range becomes lower and less rugged until entering Mpumalanga where the quartzite mountains of the Transvaal Drakensberg are loftier and more broken and form the eastern rim of the Transvaal Basin, the Blyde River Canyon lying within this stretch. The geology of this section is the same as and continuous with that of the Magaliesberg.

Mountain passes

See KwaZulu Natal Passes

Ecology

Tugela Falls vicinity – Tugela River in valley
Little Saddle

The high treeless peaks of the Drakensberg (from 2,500 m upwards) have been described by the World Wildlife Fund as the Drakensberg alti-montane grasslands and woodlands ecoregion. These steep slopes are the most southerly high mountains in Africa, and being further from the equator provide cooler habitats at lower elevations than most mountain ranges on the continent. The high rainfall generates many mountain streams and rivers, including the sources of the Orange River, southern Africa's longest, and the Tugela River. These mountains also have the world's second-highest waterfall, the Tugela Falls (Thukela Falls), which has a total drop of 947 metres. The rivers that run from the Drakensberg are an essential resource for South Africa's economy, providing water for the industrial provinces of Mpumalanga and Gauteng, which contains the city of Johannesburg.[18] The climate is wet and cool at the high altitudes, which experience snowfall in winter.

Meanwhile the grassy lower slopes (from 1,800 to 2,500 m) of the Drakensberg in Swaziland, South Africa and Lesotho constitute the Drakensberg Montane Grassland, Woodland, and Forest.

Flora

Cathedral Valley

The mountains are rich in plant life, including a large number of species listed in the Red Data Book of threatened plants, with 119 species listed as globally endangered" and "of the 2 153 plant species in the park, a remarkable 98 are endemic or near-endemic".[19]

The flora of the high alti-montane grasslands is mainly tussock grass, creeping plants, and small shrubs such as ericas. These include the rare Spiral Aloe (Aloe polyphylla), which as its name suggests has leaves with a spiral shape.

Meanwhile the lower slopes are mainly grassland but are also home to conifers, which are rare in Africa, the species of conifer found in the Drakensberg is Podocarpus. The grassland itself is of interest as it contains a great number of endemic plants. Grasses found here include oat grass Monocymbium ceresiiforme, Diheteropogon filifolius, Sporobolus centrifugus, caterpillar grass (Harpochloa falx), Cymbopogon dieterlenii, and Eulalia villosa.

Fauna

The Drakensberg area is "home to 299 recorded bird species"' making up "37% of all non-marine avian species in southern Africa."[19]

Fauna of the high peaks

There is one bird that is endemic to the high peaks, the Mountain Pipit (Anthus hoeschi), while another six are found mainly here: Bush Blackcap (Lioptilus nigricapillus), Buff-streaked Chat (Oenanthe bifasciata), Rudd's Lark (Heteromirafra ruddi), Drakensberg Rockjumper (Chaetops aurantius), Yellow-breasted Pipit (Anthus chloris), and Drakensberg Siskin (Serinus symonsi). The endangered Cape Vulture and Lesser Kestrel are two of the birds of prey that hunt in the mountains. Mammals include Klipspringer (Oreotragus oreotragus), Eland (Taurotragus oryx) and Mountain Reedbuck (Redunca fulvorufula). Other endemic species include three frogs found in the mountain streams, Drakensberg River Frog, (Amietia dracomontana), Phofung River Frog (Amietia vertebralis) and Maluti River Frog Frog (Amietia umbraculata). Fish are found in the many rivers and streams including the Maluti Redfin (Pseudobarbus quathlambae), which was thought to be extinct but has been found in the Senqunyane River in Lesotho.[20] [21]

Fauna of the lower slopes

Drakensberg Sky & Mountains

The lower slopes of the Drakensberg support much wildlife, perhaps most importantly the rare Southern White Rhinoceros (which was nurtured here when facing extinction) and the Black Wildebeest (Connochaetes gnou, which as of 2011 only thrives in protected areas and game reserves). The area is home to large herds of grazing and antelopes such as Eland (Taurotragus oryx), Reedbuck (Redunca arundinum), Mountain Reedbuck (Redunca fulvorufula), Grey Rhebok (Pelea capreolus), and even some Oribi (Ourebia ourebi). Chacma baboons are also present. Endemic species include a large number of chameleons and other reptiles. There is one endemic frog, Forest Rain Frog (Breviceps sylvestris), and four more that are found mainly in these mountains; Long-toed Tree Frog (Leptopelis xenodactylus), Plaintive Rain Frog (Breviceps maculatus), Rough Rain Frog (Breviceps verrucosus), and Poynton's Caco (Cacosternum poyntoni).

Conservation

Drakensberg Cliffs

The high slopes are hard to reach so the environment is fairly undamaged. However, tourism in the Drakensberg is developing, with a variety of hiking trails, hotels and resorts appearing on the slopes. Most of the higher South African parts of the range have been designated as game reserves or wilderness areas. Of these the UKhahlamba / Drakensberg Park was listed by UNESCO in 2000 as a World Heritage site. The park is also in the List of Wetlands of International Importance (under the Ramsar Convention). The Royal Natal National Park, which contains some of the higher peaks, is part of this large park complex. Adjacent to the Ukhahlamba Drakensberg World Heritage Site is the 1900 ha Allendale Mountain Reserve which is the largest private reserve adjoining the World Heritage Site and is found in the accessible Kamberg area, the heart of the historic San (Bushman) painting region of the Ukhahlamba.

The grassland of the lower slopes meanwhile has been greatly affected by agriculture, especially overgrazing. Original grassland and forest has nearly all disappeared and more protection is needed, though the Giant's Castle reserve is a haven for the Eland and also is a breeding ground for the Bearded Vulture.

Panorama of the Giant's Castle region

The Maloti-Drakensberg Transfrontier Conservation Area was established to preserve some of the high mountain areas of the range.[22]

Urban areas

Towns and cities in the Drakensberg area include: in KwaZulu-Natal South Africa; Ladysmith, the city of Newcastle, the former Zulu capital Ulundi, the coal-mining centre Dundee and Ixopo; and further south Matatiele and Barkly East in Eastern Cape Province, Tzaneen in Limpopo Province, plus all of Lesotho, whose capital is Maseru. The hilly landscape extends north from the Drakensberg as Swaziland, whose capital is Mbabane.

San cave paintings

Caves are frequent in the more easily eroded sandstone, and many have rock paintings by the San (Bushmen). The Drakensberg has between 35000 and 40000 works of San rock art[19][23] and is the largest collection of such work in the world. Some 20,000 individual rock paintings have been recorded at 500 different caves and overhanging sites between the Drakensberg Royal Natal National Park and Bushman's Neck.[23] Due to the materials used in their production, these paintings are difficult to date, but there is anthropological evidence, including many hunting implements, that the San people existed in the Drakensberg at least 40,000 years ago, and possibly over 100,000 years ago. According to drakensbergmountains.co.za, "[i]n Ndedema Gorge in the Central Drakensberg 3,900 paintings have been recorded at 17 sites. One of them, Sebaayeni Cave, contains 1 146 individual paintings."[24] Southafrica.info indicates that though "the oldest painting on a rock shelter wall in the Drakensberg dates back about 2400 years", "paint chips at least a thousand years older have also been found."[19] The site also indicates that "[t]he rock art of the Drakensberg is the largest and most concentrated group of rock paintings in Africa south of the Sahara, and is outstanding both in quality and diversity of subject."[19]

See also

References

  1. ↑ Encyclopaedia Britannica (1975); Micropaedia Vol. III, p. 655. Helen Hemingway Benton Publishers, Chicago.
  2. ↑ 2.0 2.1 2.2 McCarthy, T. & Rubidge, B. (2005). The story of earth and life. p. 263. Struik Publishers, Cape Town.
  3. ↑ McCarthy, T. & Rubidge, B. (2005). The story of earth and life. p. 245-248. Struik Publishers, Cape Town.
  4. ↑ Truswell, J.F. (1977). The geological evolution of South Africa. pp. 184–188. Purnell, Cape Town.
  5. ↑ Encyclopaedia Britannica (1975); Macropaedia, Vol. 17. p. 60. Helen Hemingway Benton Publishers, Chicago.
  6. ↑ Truswell, J.F. (1977). The geological evolution of South Africa. pp. 190. Purnell, Cape Town.
  7. ↑ 7.0 7.1 McCarthy, T. & Rubidge, B. (2005) The story of earth and life. p. 267-269. Struik Publishers.
  8. ↑ 8.0 8.1 Atlas of Southern Africa. (1984). Readers Digest Association, Cape Town
  9. ↑ 9.0 9.1 McCarthy, T.S. (2013) The Okavango delta and its place in the geomorphological evolution of Southern Africa. South African Journal of Geology 116: 1-54.
  10. ↑ McCarthy, T. & Rubidge, B. (2005). The story of earth and life. p. 16-17, 209. Struik Publishers, Cape Town.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 Geological map of South Africa, Lesotho and Swaziland (1970). Council for Geoscience, Geological Survey of South Africa.
  12. ↑ 12.0 12.1 12.2 McCarthy, T. & Rubidge, B. (2005). The story of earth and life. pp. 209 - 211. Struik Publishers, Cape Town.
  13. ↑ Truswell, J.F. (1977). The geological evolution of South Africa. pp. 151 - 153. Purnell, Cape Town.
  14. ↑ Sycholt, August (2002). Roxanne Reid, ed. A Guide to the Drakensberg. Cape Town: Struik Publishers. p. 9. ISBN 1-86872-593-6. 
  15. ↑ The Times comprehensive atlas of the World. (1999) p. 90. Times Books Group, London.
  16. ↑ McCarthy, T. & Rubidge, B. (2005). The story of earth and life. pp. 120 - 123. Struik Publishers, Cape Town.
  17. ↑ McCarthy, T. & Rubidge, B. (2005). The story of earth and life. pp. 199 - 202. Struik Publishers, Cape Town.
  18. ↑ "Drakensberg alti-montane grasslands and woodlands". Terrestrial Ecoregions. World Wildlife Fund. 
  19. ↑ 19.0 19.1 19.2 19.3 19.4 Alexander, Mary. "Drakensberg: Barrier of Spears". Retrieved 2008-10-03. 
  20. ↑ "Maloti Minnow". Lhwp.org.ls. Retrieved 2014-01-08. 
  21. ↑ A Complete Guide to the southern African Frogs. Louis du Preez and Vincent Carruthers
  22. ↑ Maloti-Drakensberg Transfrontier Conservation Area
  23. ↑ 23.0 23.1 "Bushman and San Paintings in the Drakensberg". Drakensberg Tourism. Retrieved 2008-10-03. 
  24. ↑ "Drakensberg Rock Art". Retrieved 2008-10-03. 
  • Rosen, Deborah; Lewis, Colin; Illgner, Peter (1999). "Palaeoclimatic And Archaeological Implications of Organic- Rich Sediments at Tifftidell Ski Resort, Near Rhodes, Eastern Cape Province, South Africa". Transactions of the Royal Society of South Africa 54 (2): 311–321. doi:10.1080/00359199909520630. 

External links

Wikimedia Commons has media related to Drakensberg.
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Major African geological formations
Plates
Cratons and Shields
Shear zones
Rifts
Sedimentary basins
Mountain ranges
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