“Drakensberg”的意思、由来-开放百科全书

The Drakensberg (Afrikaans: Drakensberge, Zulu: uKhahlamba, Sotho: Maluti) 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 elevation in this region – {{convert|2000|to|3482|m|ft|abbr=off}}. It is located in South Africa and Lesotho.

The Drakensberg escarpment stretches for over {{convert|1000|km|mi|sigfig=1|abbr=off}} from the Eastern Cape Province in the South, then successively forms, 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, and next as the border between KwaZulu-Natal and Mpumalanga Province. It winds north, through Mpumalanga, where it includes features such as the Blyde River Canyon, Three Rondavels and God's Window. It moves north again above Tzaneen in Limpopo Province, where it includes the Wolkberg Mountains and Iron Crown Mountain, at {{convert|2200|m|ft|abbr=on}} above sea level, the Wolkberg being the highest mountain range in Limpopo. It veers west again and at Mokopane it is known as the Strydpoort Mountains.^[1]^[2]

Etymology

The Afrikaans name Drakensberge comes from the name the earliest Dutch settlers to the region gave it. They called them the Drakensbergen, or "Mountains of Dragons". Several possible reasons for this name include the pointy tops giving an appearance similar to that of the back of the mythical European dragon, old local myths of dragons roaming the mountains, and possible findings of dinosaur fossils (which would have been confused with the remains of dragons).^[3]

When most South Africans and visitors speak of the Drakensberg, they 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 highest portion of the Great Escarpment is known as uKhahlamba ("Barrier of up-pointed spears")^[4] in Zulu and Maluti in Sotho.

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 become southern Africa.^[5] Within 10–20 million years rift valleys formed on either side of the central bulge, which became flooded to become the proto-Atlantic and proto-Indian oceans.^[5]^[6] The stepped steep walls of these rift valleys formed escarpments that surrounded the newly formed Southern African subcontinent.^[5]

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.^[7] An almost uninterrupted period of erosion has continued to the present, resulting in layers several kilometers thick having been lost from the surface of the plateau.^[5] 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, further massive upliftment, especially in the East, has taken place in Southern Africa. As a result, most of the plateau lies above {{convert|1000|m|ft|abbr=on}} despite the extensive erosion. The plateau is tilted such that its highest point is in the east, and it slopes gently downwards towards the west and south. The elevation of the edge of the eastern escarpments is typically in excess of {{convert|2000|m|ft|abbr=on}}. It reaches its highest point (over {{convert|3000|m|ft|abbr=on}}) where the escarpment forms part of the international border between Lesotho and the South African province of KwaZulu-Natal.^[5]^[1]

The upliftment of the central plateau over the past 20 million years and erosion resulted in the original escarpment being moved inland, creating the present-day coastal plain.^[5]^[8]^[9] The position of the present escarpment is approximately {{convert|150|km}} inland from the original fault lines which formed the walls of the rift valley that developed along the coast during the break-up of Gondwana. The rate of the erosion of the escarpment in the Drakensberg region is said to average {{convert|1.5|m|ft|abbr=on|0}} per 1000 years, or {{convert|1.5|mm|in|frac=16}} per year.^[9]

Because of the extensive erosion of the plateau, which occurred over most of the Mesozoic and Cenozoic eras, none of its surface rocks (except the Kalahari sands) are younger than 180 million years.^[5]^[10] 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 {{convert|1600|m|ft|abbr=on}} thick layer of lava which erupted, and covered most of Southern Africa, and large parts of Gondwana, about 180 million years ago.^[5]^[6]^[11] These rocks form the steep sides of the Great Escarpment in this region, where its upper edge reaches an elevation in excess of {{convert|3000|m|ft|abbr=on}}.

The erosional retreat of the escarpment from the coast to its present position, means that the rocks of the coastal plain are, with very few and small exceptions, older than those that cap the top of the escarpment. Thus the rocks of the Mpumalanga Lowveld below the Mpumalanga portion of the Great Escarpment are more than 3000 million years old.^[10] The rocks of the KwaZulu-Natal Midlands belong, in the main, to the Beaufort and Ecca Groups (of the Karoo Supergroup), aged 220–310 million years, and are therefore considerably older than the Drakensberg lavas (aged 180 million years) which cap the escarpment on the border between KwaZulu-Natal and Lesotho.^[10]

The entire eastern portion of the Great Escarpment (see the accompanying map) constitutes the Drakensberg.^[1]^[12] The Drakensberg terminate in the north near Tzaneen at about the 22° S parallel. The absence of the Great Escarpment for about {{convert|450|km|abbr=on}} 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 breakup of Gondwana about 150 million years ago. The lower Limpopo River and Save River drain into the Indian Ocean through what remains of this relict incipient rift valley which now forms part of the South African Low veld.^[5]

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 (giving rise to the Zulu name "Barrier of up-pointed spears"). Who first gave these mountains their Afrikaans or Dutch name Drakensberg, and why, is unknown.^[4]). 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 tributaries of the Orange River. The large number of tributaries give the Lesotho Highlands a very rugged mountainous appearance, both from the ground and from the air.

The higher parts of Drakensberg has a mildly periglacial environment. It is possible that recent climate change has diminished the intensity of periglaciation.^[13]

Knight and Grab mapped out the distribution of lightning strikes in the Drakensburg and discovered that lightning significantly controls the evolution of the mountain landscapes because it helps to shape the summit areas – the highest areas – with this blasting effect. Previously, angular debris was assumed to have been created by changes typical of cold, periglacial environments, such as fracturing due to frost.^[14]

Composition of rocks

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.^[5] 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.^[5]^[10] 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.^[5]^[10] 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.^[5]^[10]

Highest peaks

The highest peak is Thabana Ntlenyana, at {{convert|3482|m|ft|abbr=on}}. Other notable peaks include Mafadi ({{convert|3450|m|ft|0|abbr=on}}), Makoaneng at {{convert|3416|m}}, Njesuthi at {{convert|3408|m}}, Champagne Castle at {{convert|3377|m}}, Giant's Castle at {{convert|3315|m}}, Ben Macdhui at {{convert|3001|m}}, and Popple Peak at {{convert|3331|m}}, 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

Ecology

The high treeless peaks of the Drakensberg (from {{convert|2,500|m|ft|abbr=on}} 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 {{convert|947|m|ft|abbr=on}}. 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.^[15] The climate is wet and cool at the high elevations, which experience snowfall in winter.

Meanwhile, the grassy lower slopes (from {{convert|1,800|to|2500|m|ft|abbr=on}}) of the Drakensberg in Swaziland, South Africa and Lesotho constitute the Drakensberg Montane Grassland, Woodland, and Forest.

Flora

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".^[39]

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.

In the highest part of Drakensberg the composition of the flora is independent on slope aspect (direction) and varies depending on the hardness of the rock clasts. This hardness is related to weathering and is variable even within a single landform.^[13]

Fauna

The Drakensberg area is "home to 299 recorded bird species"' making up "37% of all non-marine avian species in southern Africa."^[39] There are 24 species of snakes in the Drakensberg, two of which are highly venomous.^[16]

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 (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.^[17]

Fauna of the lower slopes

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| lc = on}} 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

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.

The Maloti-Drakensberg Transfrontier Conservation Area was established to preserve some of the high mountain areas of the range.^[19]

Urban areas

Towns and cities in the Drakensberg area include, from South to North, Matatiele and Barkly East in the Eastern Cape Province; Ladysmith, Newcastle, Ulundi – the former Zulu capital, Dundee and Ixopo in KwaZulu-Natal; all of Lesotho, whose capital is Maseru and Tzaneen in Limpopo Province.

San cave paintings

There are numerous caves in the easily eroded sandstone of Clarens Formation, the layer below the thick, hard basalt layer on the KwaZulu Natal-Lesotho border. Many of these caves have rock paintings by the San (Bushmen). This portion of the Drakensberg has between 35,000 and 40,000 works of San rock art^[20]^[21] 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 Nek.^[21] 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 mountainsides.co.za, "[i]n Nd edema Gorge in the Central Ginsberg 3,900 paintings have been recorded at 17 sites. One of them, Sebaayeni Cave, contains 1,146 individual paintings."^[22] The website south Africa.info indicates that though "the oldest painting on a rock shelter wall in the Ginsberg dates back about 2400 years.....paint chips at least a thousand years older have also been found."^[20] 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."^[20]

In popular culture

The Drakensberg was featured in the 2009 American science fiction film 2012. It was mentioned in the last scene of the movie, where after twenty-seven days of a great flood which people tried to survive by building arks, the waters began receding. The arks approach the Cape of Good Hope, where the Drakensberg (now the tallest mountain range on Earth) emerges.

See also

References

1. ^¹²{{cite book|title=Reader's Digest Atlas of Southern Africa|url=https://books.google.com/books?id=LJPctAEACAAJ|year=1984|publisher=Reader's Digest Association South Africa|pages=13, 190–192|location=Cape Town}}
2. ^Encyclopædia Britannica (1975); Micropaedia Vol. III, p. 655. Helen Hemingway Benton Publishers, Chicago.
3. ^{{Cite web | title = Drakensbergen in Kwazulu-Natal | trans-title = | author = | work = visitafricanow.com | date = | accessdate = 2018-04-26 | url = http://www.visitafricanow.com/zuid-afrika/Kwazulu%20Natal/kw_n_drakenb.php | language = nl | quote = }}
4. ^¹{{cite book|last=Pearse|first=Reg O.|title=Barrier of Spears: Drama of the Drakensberg|url=https://books.google.com/books?id=ri6KQgAACAAJ|year=1973|publisher=H. Timmins|isbn=978-0-86978-050-3|page=i}}
5. ^¹²³⁴⁵⁶⁷⁸⁹¹⁰¹¹¹²¹³{{cite book|last1=McCarthy|first1=Terence |last2=Rubidge|first2=Bruce |title=The Story of Earth & Life: A Southern Africa Perspective on a 4.6 Billion-year Journey|url=https://books.google.com/books?id=YEa9tNO2qOcC|year=2005|publisher=Penguin Random House South Africa|isbn=978-1-77007-148-3|pages=16–7, 192–195, 245–248, 263, 267–269|location=Cape Town}}
6. ^¹²{{cite book|last=Truswell|first=J. F. |title=The Geological Evolution of South Africa|url=https://books.google.com/books?id=5gq0AAAAIAAJ|year=1977|publisher=Alice Kelly Purnell|location=Cape Town|pages=151–153, 157–159, 184–188, 190}}
7. ^Encyclopædia Britannica (1975); Macropaedia, Vol. 17. p. 60. Helen Hemingway Benton Publishers, Chicago.
8. ^{{cite journal|last1=McCARTHY|first1=T. S.|title=The Okavango Delta and its Place in the Geomorphological Evolution of Southern Africa|journal=South African Journal of Geology|volume=116|issue=1|year=2013|pages=1–54|issn=1012-0750|doi=10.2113/gssajg.116.1.1}}
9. ^¹²{{cite book|last1=Norman|first1=Nick|last2=Whitfield|first2=Gavin |title=Geological Journeys: A Traveller's Guide to South Africa's Rocks and Landforms|url=https://books.google.com/books?id=_uDcm-olXE8C|year=2006|publisher=Penguin Random House South Africa|isbn=978-1-77007-062-2|pages=290–300}}
10. ^¹²³⁴⁵Geological map of South Africa, Lesotho and Swaziland (1970). Council for Geoscience, Geological Survey of South Africa.
11. ^{{cite book|last=Sycholt|first=August |editor=Roxanne Reid|title=A Guide to the Drakensberg|url=https://books.google.com/books?id=bFo7ytU8OnUC|year=2002|publisher=Struik Publishers|location=Cape Town|isbn=978-1-86872-593-9|page=9}}
12. ^{{cite book|title=The Times Comprehensive Atlas of the World|url=https://books.google.com/books?id=KtBxcgAACAAJ|year=1999|publisher=Times Books|location=London|page=90}}
13. ^¹{{cite journal |last1=Knight |first1=Jasper |last2=Grab |first2=Stefan W.|last3=Carbutt |first3=Clinton |date=2018 |title=Influence of mountain geomorphology on alpine ecosystems in the Drakensberg Alpine Centre, Southern Africa |url= |journal=Geografiska Annaler: Series A, Physical Geography |volume= |issue= |pages= |doi=10.1080/04353676.2017.1418628 |access-date= }}
14. ^https://phys.org/news/2013-10-evidence-lightning.html
15. ^{{WWF ecoregion|id=at1003|name=Drakensberg alti-montane grasslands and woodlands}}
16. ^{{Cite book|title=A field guide to the Natal Drakensberg|last=Irwin|first=Pat|publisher=The Natal Branch of the Wildlife Society of Southern Africa|year=1983|isbn=0 949966 452|location=|pages=129}}
17. ^{{webarchive |title=Maloti Minnow |url=https://web.archive.org/web/20130602183916/http://www.lhwp.org.ls/environment/nehp/conservation/minnow/default.htm }}
18. ^{{cite book|last1=du Preez|first1=Louis |last2=Carruthers|first2=Vincent |title=A Complete Guide to the Frogs of Southern Africa|url=https://books.google.com/books?id=5EegCgAAQBAJ|year=2015|publisher=Penguin Random House South Africa|isbn=978-1-77584-349-8}}
19. ^Maloti-Drakensberg Transfrontier Conservation Area {{webarchive|url=https://web.archive.org/web/20120130182044/http://www.maloti.org.ls/home/ |date=30 January 2012 }}
20. ^¹²³⁴{{cite web|url=http://www.southafrica.info/about/geography/drakensberg-050705.htm|title=Drakensberg: Barrier of Spears| last=Alexander|first=Mary|accessdate=2008-10-03|archive-url=https://web.archive.org/web/20160303181740/http://www.southafrica.info/about/geography/drakensberg-050705.htm#.WuFxpYhua00|archive-date=2016-03-03}}
21. ^¹{{cite web|url=http://www.drakensberg-tourism.com/bushman-rock-art.html |title=Bushman and San Paintings in the Drakensberg |publisher=Drakensberg Tourism |accessdate=2008-10-03 |deadurl=yes |archiveurl=https://web.archive.org/web/20080918020735/http://www.drakensberg-tourism.com/bushman-rock-art.html |archivedate=18 September 2008 |df= }}
22. ^{{cite web|url=http://www.drakensbergmountains.co.za/bushman-rock-art.html|title=Drakensberg Rock Art|access-date=2008-10-03}}