Diamond is a crystalline form of ordinary carbon created under conditions of extreme pressure and temperature. In nature, such conditions are only found deep below the earth’s surface in the lower crust or upper mantle. Under certain circumstances in the past (usually associated with tectonic activity) the rock matrix in which diamonds occurred was subjected to such great pressure that it became fluid and welled up to the earth’s surface in a volcanic pipe of fluidised material. The situation is similar to a conventional volcanic eruption, except that instead of basaltic magma being erupted through fissures in the crust, the volcanic material is a peculiar rock called kimberlite. This contains a wide assortment of minerals (including diamond) in addition to large chunks of other rocks that have been caught up in the process.
The pipes are correctly termed kimberlite pipes, and occur throughout southern Africa from the Cape to Zaire. However, only a small proportion of those discovered have proved to contain diamonds in sufficient abundance to be profitably worked. Namibia’s diamonds derive not from primary kimberlite pipes, but from secondary diamond deposits – areas where diamonds have been washed down and deposited by old rivers, which have eroded kimberlite pipes in the interior on their way.
The topography of Namibia can be divided into four regions. At 2,000m, the highest land is the central plateau that runs roughly from north to south, from south of Keetmanshoop to north of Otjiwarongo. This is hilly and much is under commercial ranches.
On the west side of this, toward the Atlantic Ocean, the land falls off in a steep escarpment down to the Namib Desert’s narrow coastal strip. This escarpment, and the incisions that have been cut through it by river action over the years, provides some of Namibia’s most spectacular scenery. Below, the Namib is a flat coastal plain whose profile is broken only by shifting dunes and the odd towering inselberg.
East of that central plateau, the land slopes off much more gradually, merging into the great sand-sheet of the Kalahari Desert – a plateau standing at about 1,000m, stretching from Namibia into Botswana and even beyond.
Barchan, or crescentric, dunes arise wherever sand-laden wind deposits sand on the windward (up-wind) slopes of a random patch on the ground. The mound grows in height until a ‘slip-face’ is established by sand avalanching down on the sheltered leeward (down-wind) side. The resulting dune is therefore in a state of constant (if slow) movement – sand is continuously being deposited and blown up the shallow windward slope and then falling down the steep leeward slope. This slow movement, or migration, is more rapid at the edges of the dune (where there is less wind resistance) than in the centre, which results in the characteristic ‘tails’ of a mature barchan.
Fairly constant winds from the same direction are essential for the growth and stability of barchan dunes, which can migrate from anything up to six metres a year for high dunes to 15 metres a year for smaller dunes. Probably the best examples of barchan dunes occur in Namibia’s Skeleton Coast, where some of the dune crests are highlighted by a purple dusting of garnet sand. You’ll see them ‘marching’ across the road near where the D2345 turns from the main C34 coastal road.
Where the prevailing wind is interrupted by crosswinds driving in sand from the sides, a long seif or longitudinal dune is formed, instead of a swarm of barchans. The shape of seif dunes is that of a long ridge with high crests, parallel to the direction of the prevailing wind. They commonly occur in long parallel ranges, such as those south of the Kuiseb River which show up so clearly on satellite photographs.
Sand sheets occur when the land is vegetated with grass and scrub, or is covered with rocks and pebbles. Then the force of the wind is broken and it becomes less homogenous. In such situations poorly developed seif dunes or irregular barchans form, and may often join together to some extent, making an undulating sand sheet. From this platform of coarser sand, more erratic dunes often rise.
Sand sheets, in one form or another, are the most common dune formation in southern Africa, since the ‘text book’ conditions needed to form perfect barchan or seif dunes are rare. However, the principles remain the same and ‘imperfect’ dunes of barchan or seif origin are widespread throughout the Kalahari and Namib deserts.
The Fossil Desert
Though the Namib is one of the world’s oldest deserts, many insist that the Kalahari doesn’t qualify for the title ‘desert’ as it receives much more than 100mm of rain per year. However, the sandsheet that covers the Kalahari results in virtually no surface water, and evidence suggests that it once may have been much more arid than it is now. So although it is commonly called a desert, a better description of it would be ‘a fossil desert’.
FLORA AND FAUNA
As with animals, each species of plant has its favourite conditions. External factors determine where each species thrives, and where it will perish. These include temperature, light, water, soil type, nutrients, and which other species of plants and animals live in the same area. Species with similar needs are often found together, in communities which are characteristic of that particular environment. Namibia has a number of such communities, or typical ‘vegetation types’, within its borders – each of which is distinct from the others. East of the desert, some of the more common include:
The dominant tree here is the remarkably adaptable mopane (Colophospermum mopane), which is sometimes known as the butterfly tree because of the shape of its leaves. It is very tolerant of poorly drained or alkaline soils and those with a high clay content. This tolerance results in the mopane having a wide range of distribution throughout southern Africa; in Namibia it occurs mainly in the higher, slightly wetter areas including Etosha, the northern Kaokoveld, Caprivi and the Kalahari.
Mopane trees can attain a height of 25m, especially if growing on rich, alluvial soils. However, shorter trees are more common in areas that are poor in nutrients, or have suffered from extensive fire damage. Stunted mopane will form a low scrub, perhaps only 5m tall. All mopane trees are deciduous, and the leaves turn beautiful shades of yellow and red before falling in September and October.
Ground cover in mopane woodland is usually sparse, just thin grasses, herbs and the occasional bush. The trees themselves are an important source of food for game, as the leaves have a high nutritional value – rich in protein and phosphorus – which is favoured by browsers and is retained even after they have fallen from the trees. Mopane forests support large populations of rodents, including tree squirrels (Peraxerus cepapi), which are so typical of these areas that they are known as ‘mopane squirrels’.
This all-encompassing category refers to those areas of dry, thorny woodland that occur when trees and shrubs have invaded open grassland, often because of some disturbance like cultivation, fire or over-grazing. It could be subdivided further into Thorntree, Bush and Mixed Tree and Shrub Savannah.
Some form of savannah covers much of the Namibian highlands, and the dominant families of trees and bushes are the Acacia, Terminalia (bearing single-winged seeds) and Combretum (bearing seeds with four or five wings), but many others are also present.
In a few areas of the Kalahari (including some within Kaudom National Park), the Zambezi teak, Baikaea plurijuga, forms dry semi-evergreen forests on a base of Kalahari sand. This species is not fire-resistant, so these stands occur only where slash-and-burn cultivation methods have never been used. Below the tall teak is normally a dense, deciduous thicket of vegetation, interspersed with sparse grasses and herbs in the shadier spots of the forest floor.
Moist evergreen forest
In areas of high rainfall, or near main rivers and swamps where a tree’s roots will have permanent access to water, dense evergreen forest is found. This lush vegetation contains many species and is characterised by having three levels: a canopy of tall trees, a sub-level of smaller trees and bushes, and a variety of ground-level vegetation. In effect, the environment is so good for plants that they have adapted to exploit the light from every sunbeam. In Namibia, this occurs only as riparian forest (sometimes called riverine forest), which lines the country’s major rivers.
A vlei is a shallow grass depression, or small valley, that is either permanently or seasonally wet – though Namibia’s vleis are drier than the areas that one would call vleis in countries further east. These open, verdant dips in the landscape usually support no bushes or trees. In higher valleys amongst hills, they sometimes form the sources of streams and rivers. Because of their dampness, they are rich in species of grasses, herbs and flowering plants. Their margins are usually thickly vegetated by grasses, herbs and smaller shrubs.
Floodplains are the low-lying grasslands on the edges of rivers, streams, lakes and swamps that are seasonally inundated by floods. Namibia has only a few floodplains, in the Caprivi area. The best examples are probably beside the Okavango in Mahango, and near the Chobe and Zambezi Rivers in the Impalila area. These contain no trees or bushes, just a low carpet of grass species that can tolerate being submerged for part of the year.
Though not an environment for rich vegetation, a pan is a shallow, seasonal pool of water with no permanent streams leading into or from it. The bush is full of small pans in the rainy season, most of which will dry up soon after the rains cease. The Etosha and Nyae Nyae pans are just much larger versions, which attract considerable numbers of migrant birds when full.
Weighty tomes have been written on the flora of the Namib Desert, with its endemic plants and multitude of subtly different vegetation zones. One of the easiest to read (see Further Reading) is Dr Mary Seely’s excellent book The Namib, which is widely sold in Namibia. This is well worth buying when you arrive, as it will increase your understanding and enjoyment of the desert immensely.
Distance from the coast and altitude are crucial to note when looking at the Namib’s flora, as both are factors in determining how much moisture a plant receives by way of the fog. This is maximised at an altitude of about 300–600m above sea level, and extends up to about 60km inland. Thus the communities of vegetation can differ widely over very small distances: the plains full of delicate lichens in one place, and empty a kilometre away. Adaptations to the extremes are all around: wax-covered leaves to reduce transpiration, hollow stems to store water, low growth to avoid the wind, slow growth to take advantage of the infrequent moisture.
The species differ too widely to describe here, but are mentioned in the relevant chapters. Many will become familiar to even a casual observer; none could forget the prehistoric welwitschia (Welwitschia mirabilis), the kokerbooms silhouetted on rocky mountainsides, or the strange halfmen seen in the far south.
Namibia’s large mammals are typical of the savannah areas of southern Africa, though those that rely on daily water are restricted in their distributions. With modern game-capture and relocation techniques, you may well find animals far out of their natural ranges. (Bontebok and black wildebeest, for example, are native to South Africa but are now found on many ranches in Namibia.) Thus what you may see in a given area may be different from what ‘naturally occurs’.
The large predators are all here in Namibia. Lion are locally common, but largely confined to the parks and the Caprivi area away from dense habitation.
Leopard are exceedingly common throughout the country, and the central highlands provide just the kind of rocky habitat that they love. They are, however, very rarely seen naturally.
Cheetah do exceptionally well in Namibia, which is said to have about 40% of Africa’s population. This is mainly because commercial farmers eradicate lion and hyena relatively easily, and allow smaller buck, the cheetah’s natural prey, to coexist with cattle. Hence the cheetahs thrive on large ranches –having problems only if the farmers suspect them of killing stock and try to eradicate them also.
Wild dog have a stronghold in the wild areas around Kaudom, but are seldom seen elsewhere. They need huge territories in which to roam, and don’t survive well on commercially farmed land. Recent attempts to reintroduce them to Etosha have failed; it is hoped that some may succeed in the future.
The social spotted hyena is common in the north and northwest of the country, and even occurs down into the Namib’s central desert areas and the Naukluft mountains – though it is not common here. Much more common and widespread is the solitary, secretive brown hyena, which is common by the coast, where it can even be seen scavenging amongst the seal colonies.
Buffalo occur in protected national parks in the Caprivi, and have been re-introduced to Waterberg from South Africa, but are not found elsewhere in Namibia.
Elephant occur widely in the north, in Kaudom, Caprivi and Etosha. A separate population has its stronghold in the Kaokoveld. Many venture right down the river valleys and live in desert areas: these are the famous ‘desert elephants’. They survive there by knowing exactly where the area’s water-holes are, and where water can be found in the rivers. This ancestral knowledge, probably passed down the generations, is easily lost, although in recent years various conservation/development schemes in the area have been so successful that these ‘desert-adapted’ elephants are now thriving.
Black rhino occur in similar areas, but poaching now effectively limits them to some of the main national parks, and the less accessible areas of the Kaokoveld. Their numbers also are doing very well, and those in the Kaokoveld form one of Africa’s only increasing black rhino populations: success indeed for an area outside any national park where only community conservation schemes stand between the poachers and their quarry. White rhino have been re-introduced to Waterberg and Etosha, where they seem to be thriving.
Antelope are well represented, with springbok, gemsbok or impala being numerically dominant depending on the areas. The rare endemic black-faced impala is a subspecies found only in northwestern Namibia and southern Angola.
Roan antelope are found in the Caprivi, Waterberg and Etosha. Sable occur only in the Caprivi, with excellent numbers often seen on the Okavango’s floodplains on the edge of Mahango. In the Caprivi’s wetter areas there are also red lechwe and the odd sitatunga.
Red hartebeest are widespread in the north and east, though common nowhere. Blue wildebeest are found in Etosha and the north, as are giraffe. Eland occur in Etosha and the Kalahari, whilst Kudu seem the most adaptable of the large antelope, occurring everywhere apart from the coastal desert strip – and also eastwards to the Indian Ocean.
Amongst the smaller antelope, duiker are common everywhere apart from the desert, as are steenbok. Klipspringer occur throughout Namibia’s mountains. Namibia’s smallest antelope, the Damara dik-dik, is endemic to the area around the Kaokoveld and Etosha.
Much of Namibia is very dry, and thus hasn’t the variation in resident birds that you might find in lusher environments. However, many of those dry-country birds have restricted distributions, and so are endemic, or close to being so. Further, where Namibia’s drier interior borders on to a wetter area, as within Mahango National Park, the species count shoots up.
In addition to its residents, Namibia receives many migrants. In September and October the Palaearctic migrants appear (ie: those that come from the northern hemisphere – normally Europe), and they remain until around April or May. This is also the peak time to see the intra-African migrants, which come from further north in Africa.
The coastal wetland sites, most notably around Walvis Bay and Sandwich Harbour, receive visits from many migrating species, as well as seabird species that aren’t normally seen in the interior of southern Africa. So visits including the Caprivi and the coast, as well as the country’s interior, make Namibia an excellent and varied destination for birding trips.
Inevitably the rains from December to around April see an explosion in the availability of most birds’ food: seeds, fruits and insects. Hence this is the prime time for birds to nest, even if it is also the most difficult time to visit the more remote areas of the country.
Finding field guides to plants, animals and birds whilst in Namibia is relatively easy; though it can be difficult outside of the country.
There are some comprehensive little hardback guides on the flora of various areas, including Namib Flora and Damaraland Flora published by Gamsberg Macmillan in Windhoek. These are sold in Namibia and marketed with visitors in mind as well as locals.
The standard birding guide to travel with is still Newman’s Birds of Southern Africa, which is widely available overseas. For mammals Chris and Tilde Stuart’s Field Guide to Mammals of Southern Africa is generally very good.
The Shell guides to The Namib and Waterberg are excellent for appreciating the area’s flora and fauna. Doubtless more will appear for various other areas in due course. See the Further Reading for details of those mentioned above.