Naukluft Mountains

 

The Namib Naukluft Mountains are situated along the western margin of the interior highlands of Namibia, the Naukluft Mountains form part of the Great Escarpment - the great divide in the southern African land surface that separates the interior from the coastal lowlands.

GEOLOGY:

The formation of the escarpment is widely considered to have resulted from a sudden uplift of the sub-continent more than 65 million years ago. This was probably shortly after the break-up between Africa and South America to form the Atlantic Ocean.
The relatively flat, plateau-like, top of the escarpment represents, like most of the interior, a much older, mature land surface that formed through long periods of erosion prior to this uplift.

During more recent times, thick deposits of sand and gravel have accumulated filling the deeply incised valley at the foot of the escarpment. Most of this probably took place under dry, arid to semi-arid climatic conditions as they exist today, interrupted only by brief periods of higher rainfall.

Record of the geological history of the Naukluft Mountains is preserved in the rocks exposed in and around the area. Most of these are sedimentary rocks which consist mainly of limestone and dolomite that formed some 600 to 700 million years ago when most of the southern portion of Namibia was submerged below a warm shallow sea.

Two parts of this sequence are distinguished. The lower part consists of the very characteristic black Nama limestone. This rests on a much older basement of granite, gneiss, schist, lava and quartzite found mainly in the foothills of the escarpment and forming the scattered inselbergs at the edge of the Namib.

The upper part of the dolomite-limestone formations of the Naukluft Mountain belong to what geologists refer to as the Naukluft nappes. These consist of faulted and folded rocks that were emplaced into their present position, above lower black limestone, along a sub-horizontal fault plane, known as a thrust. Earth forces responsible for these movements are believed to be connected to geological events which took place between 500 and 550 million years ago, when in a wide belt, centred over the present Khomas Hochland, intense compression within the earth's crust resulted in active mountain building on a scale that can be compared with that of the European Alps. The nappes of the Naukluft Mountain are a relict of the foreland of this ancient mountain chain, which has since been eroded down to its roots.

As stated, the Naukluft Mountains consist mainly of limestone and dolomite and over millions of years, during wetter cycles, rain water dissolved the limestone and dolomite forming large underground caverns. Water is stored in this underground drainage system and is slowly released. This forms the many fountains, or springs, and crystal clear pools for which the Naukluft is renowned.

As the lime-rich spring water flows down the mountain streams, it loses carbon dioxide and deposits calcium carbonate. This is a slow process and the porous nature of the carbonate deposits is the result of the decay of mosses and other plant-matter being cemented by the calcium carbonate. This formation is known as tufa and there are a number of large tufa deposits in the Naukluft Mountains which are no longer developing. These large relict tufas thus reflect episodes of higher groundwater discharge at those spring sites, probably as a consequence of high water tables during past periods of increased rainfall.

CLIMATE:

The summers are very hot, but frequently there is a cool breeze on top of the plateau. Summer rainfall usually occurs from February to April, with an average of 195 mm in the mountains, but it is highly variable with a range from 50 mm to 530 mm per year. Because rain often damages the mountain track, the trail may be closed until repairs can be made. 

Winter temperatures can drop to below freezing point at night, while the days are relatively warm. At times it is very windy and mist can cover the plateau, making it cold and wet. Altitudes vary from 1 300 m on the plains to 1 988 m on the plateau.

FLORA:

The plains at the base of the mountains are covered in places by shrubs such as driedoring, Rhigozum trichtomum, and trumpet thorn, Catophractes alexandri, and are crossed by numerous watercourses, with shepherd's tree, Boscia albitrunca, buffalo thorn, Ziziphus mucronata, umbrella thorn, Acacia tortilis and wild ebony, Euclea preudebenus growing in them. As you climb higher, the valley-sides and mountain slopes are sparsely vegetated with species such as paper-bark, Commiphora glaucescens, Euphorbia virosa and quiver trees, Aloe dichotoma and the small gouty vine, Cyphostemma bainesii.

An interesting plant on certain slopes is the resurrection plant, Myrothamnus flabellifolius. When conditions are unfavourable, the bush reduces its physiological activities to a minimum. When rain falls, the change is dramatic. Within an hour, the leaves open and turn green. The leaves and twigs are used to make an aromatic tea.

The riverine valleys, some with perennial springs which form large pools, have huge wild fig trees, Ficus sycomorus, F. cordata, the lovely karee, Rhus lancea and sweet thorn, A.karroo. At these pools the pleasant smelling wild mint, Mentha longifolia subsp.wissii, is found.

The plateau is sparsely covered in Karoo-type vegetation, with small shrubs such as kapok bush, Eriocephalus ericoides, hardy Euclea asperima and occasional shepherd's trees, buffalo thorn and mountain acacia, Acacia hereroensis.

FAUNA:

The Naukluft Mountains not only have spectacular scenery, but also large numbers of Hartmann's mountain zebra, Equus zebra hartmannae, and you may see them thundering past within metres of your vehicle. Their social organisation is based on a family group of a stallion with his mares and their foals. Bachelors also form groups and at times join family groups. Family groups come together to form herds of 30 to 40 individuals.

The hooves of the Hartmann's zebra are quick growing to compensate for the rapid wear on the rocky substrata. The many holes or dust-baths, often on the track, are made by zebra. Dust bathing can primarily be described as a grooming action.

While mountain zebra are the most abundant large herbivore, there are also many kudu, often seen near Fig Fountain. Klipspringers are to be found on the slopes and on the plateau. Springbok herds are resident on the plateau and at certain times of the year are joined by gemsbok in small groups.

The largest predator is the leopard, but this elusive cat is seldom seen. Other predators include caracal, small spotted cat, African wild cat, small spotted genet and black-backed jackal. Spotted hyenas are occasional visitors from the west of the park. Baboons are common on the lower slopes, as are rock dassie and dassie rats.

BIRDS:

The Naukluft mountain complex is situated at the junction of the Damaraland and Karoo zoogeographical areas. This is thus the southern limit of the distribution of many Damaraland species such as white tailed shrike, Herero chat, Ruppell's korhaan and Monteiro's hornbill.

This is also the northern limit of the distribution of Karoo species such as Karoo robin and cinnamon breasted warbler. Black eagles breed on the high cliffs and several nests can be seen from the trail. Augur and jackal buzzards are also to be seen. Rosy faced lovebirds and pale winged starlings are common as are red eyed bulbuls. On the plateau Ludwig's bustard, long billed and Sabota larks, pale chanting goshawks and the occasional capped wheatear can be seen, and possibly the rufouseared warbler. In the ravines you may see Layard's titbabbler or the lesser honeyguide. (A complete bird check-list is obtainable at the Naukluft office.)

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