THE WATERBERG GEOLOGY
Part of the escarpment at Mamatlakala village
Spectacular rocks rise out of the bushveld easily showing the geology of the area. The Waterberg, as its name suggests, was once a well-watered system of great rivers, swamps and inland lakes. Unlike other mountain ranges, the Waterberg was not pushed up by continental drift or volcanic activity, it is structural remains left from erosion processes. In comparatively recent geological history the land around the sandstone mountains eroded away, leaving the landscape we see today.
Waterberg landscape
This flat top hill is known as Tafelkop and is a remnant of the original floor of the Waterberg Plateau, showing the surrounding land that has been eroded away over time.The Waterberg started forming in the very distant past, some 2.7 billion years ago. At this time the area was a thick stable crustal base called the Kaapvaal Craton. Volcanic rocks such as granite was pushed up through the craton, these rocks are called the Bushveld Igneous Complex and contained rich pockets of platinum, chromes, vanadium and tin.
Two billion years ago the Earth’s atmosphere began to increase its oxygen levels. Then 1.8 billion years ago the Waterberg Super-group rocks started to form over the Bushveld Igneous Complex, through the process of sedimentation. These rocks can be seen in the present day Waterberg from the red, orange and purple colours of the rocks of the plateau and escarpments.
The rusted iron particles trapped in the sandstones caused the red coloration of the rocks which are called ‘red beds’ by geologists.These rock colours were produced when sands and gravels that had been eroded from granite hills and quartz ridges were transported and deposited by streams and lakes. Here they oxidised with iron and manganese in the water and the newly oxygenated atmosphere of the Earth. These sediments over time built up became the sedimentary rocks of the Waterberg we see today.Since this time the Waterberg has remained largely geologically stable, even though other areas of the world has experienced major geological movements and processes.
Close up view of sandstone rock of the Waterberg.
In the lower layers of the Waterberg, several layers of impressive conglomerates occur. These are made up of rounded pebbles or cobbles of varying composition that have been cemented together. It is formed by rivers flowing at high speed, when there is enough energy to transport and deposit the stones.
The thick accumulation (spanning millions of years of sedimentation) of sedimentary rocks (sandstone and conglomerate) is why the Waterberg is scarce in minerals deposits which has limited mining to edges of the plateau, such as the area north of Mokopane.
