Sunday 23 June 2019

THE BIRTH OF THE DRAKENSBERG - THE ANCIENT ROCKS

DRAKENSBERG
KwaZulu-Natal  South Africa


Mountain of the Dragons

South Africa’s mightiest mountain range with its spear-like peaks – reminiscent of the saw-toothed spine of a gigantic dragon.

 Where Adventure beckons..........






DRAKENSBERG WILDERNESS PHOTOS © WILLEM PELSER





"FOR WHAT IS THERE IN ALL THE WORLD FOR ME
BUT WHAT I KNOW AND SEE?
AND WHAT REMAINS OF ALL I SEE AND KNOW
IF I LET GO?”
GW Young










THE BIRTH OF THE DRAKENSBERG
THE ANCIENT ROCKS

 The High Berg is a continuous escarpment, wild and rugged, varying in height and broken only in places where mountain passes and deep cutbacks break the line of the vertical face. An interesting feature, and one that enhances the beauty of the range, is the major spurs which extends at right angles to the escarpment.


   From the base of the sheer faces of the High Berg, steep grass-covered slopes and fingerlike minor spurs lead down to a terrace known as the Little Berg. These spurs also tend to run at right angles to the Main Berg, ending abruptly as sandstone cliffs which overlook the deep river valleys.


   Looking up towards the summits from the valleys below one can see a cross -section of a geological history going back 190 million years.


   The story of how the mightiest mountain wall in South Africa was formed belongs to an era when the foundation, or basalt layer, of the Berg was part of a vast continent called Gondwanaland. This super-continent included Africa, Australia, New Zealand, South America, as well as Antarctica.




   The basal layers of the Drakensberg which are mostly covered and only exposed in deep river valleys and road cuttings were part of a vast water-filled basin which extended from the Southern Transvaal and included Natal and a large part of Southern Africa. For countless millions of years sand and mud were washed into this vast depression from surrounding, uplifted areas until eventually it was transformed into a shallow swamp – a place where the Dinosaurs lived and died, having struggled to survive among huge ferns, cycads and conifers. These Dinosaurs originally evolved from the Thecodont reptiles and they ranged from the birdlike forms to the huge monsters which have been estimated to weigh as much as 35 tonnes. As these creatures died, so their heavy bodies sank deep into the mud and their bones were entombed in layers of mud and sand.


   Only the winds that still blow over the mountains can tell us how long it took for the immense marshes to dry out, preserving the bones of the prehistoric creatures. Relentlessly the wind blew and blew, depositing sand across the Gondwana surface, filling the depression that was once a lake and then a swamp. All that remained of this marshy paradise was windswept desert as layer upon layer of sand filled the vast depression.




   Somewhere between the middle Jurassic and Early Cretaceous age, volcanic eruptions occurred and the earth shook as great fissures opened and boiling fiery lava poured out over the interior of the Gondwana continent, until this volcanic crust was about 1400 meters thick. Once this crust has cooled, a major global upheaval caused the entire Gondwana continent to fracture, breaking up the Mother continent into smaller continents as we recognize them today.


   So Africa was born and when this break-up took place over 100 million years ago, South Africa retained the sediments capped with a volcanic crust. But still there was no Drakensberg. The Drakensberg was then a dark, arid, desolate undulating mass of basaltic lava overlying layers of sandstone and shale. Towards the Natal coast the undulating landscape dipped into the newly-formed Indian Ocean.





   Clouds appeared on the horizon and lightning, water, and wind eroded the surface of this basaltic mass. Rivulets became rivers which bit into the surface like ravenous animals.


   Soon valleys and ridges appeared and as the basaltic surface was carved it retreated in a westerly direction and so the Drakensberg was formed, first cutting through the lavas and then exposing the deeper sedimentary layers.


  All that now remains is Lesotho and the Drakensberg which proudly stands as a noble monument to that long forgotten Gondwana continent.


   Visitors to the Berg can easily distinguish the various geological strata by looking up towards the heights from the deep river valleys below.





  The basal layers of the range belong to the upper Beaufort Beds of the Beaufort Series. Overlying them, in almost parallel layers, are the various beds of the Stormberg series.


  Although the Upper Beaufort Beds are seldom exposed, except in deep river beds or in road cuttings, they can be recognized by bands of red and maroon as well as blue and green mudstones with fine-grained sandstone. Fossils of Lystrosaurus have been found in these beds particularly in the Bergville and Loskop areas. These beds form the crest of the Drakensberg at Van Reenen’s Pass as well as neighboring peaks, and were laid down about 190 million years ago when mosses, ferns, and conifers grew in the vast swamp where reptiles thrived in a warmer, drier climate. The climate gradually changed and there seems to have been a sudden disappearance of the reptiles, although plant fossils are common.

   Lying directly on top of these beds are the Molteno Beds, the oldest of the Stormberg Series, which can be recognized by the blue and grey color of the shales with sparkling grained sandstone. They were laid down about 180 million years ago. Vertebrate fossils are rarely found in these beds. The Molteno Beds are responsible for the terracing so commonly seen below the cave sandstone. Bushmen used the even surfaces of these beds to display their primitive art. Later farmers used the dressed sandstone to build their houses, which can still be seen today.





   Lying immediately above the Molteno Beds are the Red Beds, derived from the red and purple mudstone and occasional beds of sandstone. It is in these layers that the enormous silicified tree trunks of the Dadoxylon are to be found as well as the fossils of those giants of the swamps, the Dinosaurs. Fossil remains as well as footprints have been found in several places on the Lesotho side of the range. Plant fossils can also be found in these beds.


   Towards the end of period when the Red Beds were laid down, a long era of desiccation followed, converting the one time swamp into a desert as winds piled up the sand particles blown from other areas, to the height of the sandstone cliffs that we see along the whole length of the Drakensberg today.





   It is difficult to differentiate where the Red Beds and The Cave Sandstone begins. The Cave Sandstone was laid down about 160 million years ago and consists of a series of bedding planes of fine-grained sand particles. These massive, generally white to cream colored cliffs are the most spectacular aspect of the Little Berg, and can reach a height of 200 meters. In places erosion has carved the sandstone cliffs into weird and amazing sculptures that sometimes assume familiar shapes. Typical examples are the Mushroom Rock and the Baboon Rock in the Cathedral Peak area, The Policeman’s Helmet, the Frog, the Tortoise, and the Crocodile at Royal Natal National Park in the Mount-aux –Sources area.





   Over the years the forces of erosion created rock-shelters at the base of these massive cliffs. These eventually became the homes of the Bushmen, the smooth walls proving an ideal surface for them to display their art.





   Towering above the Little Berg is the gigantic wall of basalt which was laid down 150 million years ago as molten lava poured out of fissures in successive eruptions from 1 meter to 50 meters thick, with a time lapse between each eruption. As the flow cooled so gas bubbles rose towards the surface. A close look at a large piece of basalt reveals pipelike vesicles filled with amygdales. Common amygdales found along the contour paths on the top of the Little Berg are agates, quartz crystals, chalcedony, and zeolites.


   After the snow has fallen, the layers of basalt become more obvious. Dolerite is similar to basalt in its chemical composition but is cooled under pressure. Many dolerite dykes were the feeder fissures through which the molten lava flowed. Two examples of dolerite dykes are the Crack in the Royal Natal Park where the dolerite has weathered much faster than the sandstone, creating the crack, and another example is the dolerite dyke in the Bannerman’s Pass which follows the line of the pass.





   And so from its marshy grave the Drakensberg was born, lashed by the winds of time, scorched and smothered by the fiery lavas, then carved by the wrath of erosion, leaving a mountain paradise supporting vast herds of game feeding off the grasslands which covered the scars of erosion.


Then suddenly out of the mists appeared the little yellow hunters who found peace and happiness in the mountain fastness – the Bushmen.




We as hikers, explorers, and adventurers have the absolute duty to respect and protect our Wildernesses. Nobody else will do it for us. Take ownership!



The End.


Safe Hiking.




References and Acknowledgements

From the book – “A Cradle of Rivers, The Natal Drakensberg – DA Dodds.”

Photos:  ©Willem Pelser
Compiled by Willem Pelser