Sand Dunes

Sand


When admiring the spectacular view of the Namib dunes one can sometimes forget about the smaller detail. Scoop up a handful of sand, let it trickle through your fingers, smell it, literally get the feel of the dunes. Scoop some sand into the palm of your hand, then take binoculars and use them wrong way around to have a look at the particles of sand in your hand. The colours will amaze you, from white quartz to red garnets, the blacks and yellows, all in the palm of your hand.


Scientists tell us that sand must not be larger than 2.0 mm, or smaller than 0.05 mm in diameter. If bigger it is classified as gravel and if smaller silt, and then clay. Sand is simply large rock formations that have been eroded over millions of years. A granite boulder will be eroded by wind and water, and later this little piece of rock will slowly find its way into a river wash. Once the river comes down, this little piece will be ground against other rocks and eventually become polished smooth.


These little pieces of rock will find its way into the ocean, where they accumulate and then get compressed by heavier material. The chemical action of the ocean “cement” these layers, and thus sandstone is formed. Once the ocean level drops the sandstone is once again exposed to wind and weather, and the erosion process starts again.


According to the scientists most of the sandstone was formed in the Southern Namib, where it was transported to the ocean by the Orange River. From here it was moved North by the Benguela current, and then thrown out onto the beach of the Namibian coastline. Once on the coast, the predominantly south-westerly wind will continue the journey of this grain of sand.


To complete the life cycle of a grain of sand, it gets polished by all the other sand particles around. Getting wet from the fog and then drying in the hot sun again, caused the grains of sand to form a translucent film over them. Call it “frosting” if you want. The last process that gives the orange colour to the sand is known as oxidation.


From sandstone to sand, transported thousands of kilometres, getting polished, and that is maybe how the sand of the Namib dunes was formed. At sunset the orange colour of the dunes can become a deep red, and that is exactly why it is so fascinating in the dunes. It is never the same from hour to hour.

The Namib Sand Sea

The “sand sea” of the Namib Desert stretches from Luderitz in the south, past the Kunene River in the North. The biggest and most dunes are found between Luderitz and the Kuiseb river. Life in these dune fields are complex and utterly fascinating to observe.


Driving south from Walvis Bay you need to cross the Kuiseb delta in order to enter the dunes proper. Here your fascinating journey begins.


The first fascinating plant you will see is the !Nara bush. This thorny green bush produces melon like fruits that is harvested annually by the Topnaar people, living in the Kuiseb River.


Although the desert looks devoid of life, there is plenty to see. The dune grass or Stipagrostis sabulicola, is the main specie found in the dune fields. This very tough grass mostly grows in hollows and the lower part of dune slopes. It has an extensive root system, which can sometimes be seen above ground. It utilises the fog that crawls in over the land from the Atlantic ocean every night, to sustain itself.


Sand borne by the wind gets blown around, and will accumulate at the base of the dune grasses, thus causing hummocks. These hummocks in turn can sustain a wide variety of life.


The Golden Mole, the only known mammal to dwell entirely in sand, will use the hummock to burrow in before day break. Extremely shy and elusive the Golden Mole is very difficult to find, but its “tunnels” can be seen easily enough. The Golden Mole “swims” through the sand in order to move and catch its prey. Another inhabitant of these hummocks is gerbils. These jumping mice also burrow in during the day, to escape the heat of the day.


Side winding adders are attracted to these hummocks for the sole reason that it provides food like gerbils, beetles and even golden moles if they can catch them. Other inhabitants include geckos of different species, beetles and even the odd chameleon. Dune ants are what can be seen mostly. They are about the only living thing that moves around during the day, and they also use the hummock of dune grass as their home.


The dunes of the Namib are very special indeed. Not only do they look very pretty, but they support a large number of species. At times it might be difficult to see them, but once you know what to look for, these fascinating denizens of the Namib will show themselves.