The foundation of what is now the Tankwa Karoo was essentially laid hundreds of millions of years ago when planetary tectonic forces created a large shallow basin bounded on its southern and southeastern fringes by the Cape fold mountains - part of which are today visible on the eastern boundary of Tierkloof in the form of the Cederberg and its component Swartruggens range.
Effectively a vast, shallow and sometimes ice-covered sea at most points in its geological past, the Tankwa basin is characterized by extremely deep, multiple layers of sedimentary deposits. Subsequent geological upheaval and erosion, along with a significant drop in sea level, has exposed these sedimentary strata as fascinating outcrops, folds and other topographical features. The oldest of these are remnants of sediment laid down during the Dwyka ice age, some 360-280 million years ago. These outcrops occur only on the edges of the basin, particularly in the southern areas such as where Tierkloof is located. For those who are interested, there are two beautiful and rather strange Dwyka tillite outcrops (kopjies) straddling the Tankwa Road within clear sight of all three cottages which are well worth a close-up visit. Interestingly, these and the other ages (groups) of exposed sedimentary rock reveal many geological and paleontological features supporting the existence of a single primaeval Southern supercontinent that would eventually erode and drift to form what we know today as Africa, South America, the Antarctic, Australia and the subcontinent of India. These new continents resultantly share common geological features and fossil types unseen anywhere else on earth - despite being separated by thousands of kilometres of sea.
The sedimentary nature of this area lends itself to the preservation of animal and plant fossils and unsurprisingly the region's remaining exposed rock strata have proven rich in paleontologically important content.
The Tankwa, and more specifically, the Cederberg and Swartruggens mountains on its southwestern flank, is also well known for its abundant evidence of the existence of Southern Africa's stone-age San people (often referred to collectively along with the coastal Khoekhoe people as the Khoisan or Bushmen). It is thought that the ancestors of the modern Khoisan expanded to Southern Africa over 150,000 years ago, and possibly as early as over 260,000 years ago. Unsurprisingly, cave and rock paintings, as well as stone implements and other evidence of their habitation, abound, dating from tens of thousands of years to not more than a few centuries ago.
The advent of European explorers and their subsequent trek into the interior from the coast upset the stability of both the indigenous population and the region's ecology. So it was that the late 1600s onwards saw the Tankwa Karoo being explored and settled by mostly Dutch immigrants, who wiped out or pushed any remnant San northwards. These settlers proclaimed as their own and presided - and in many cases, their descendants still do today - over large tracts of land on which the raised hardy sheep suited to the dry climate. Grazing and overuse of limited water resources saw large areas being partially denuded. Luckily Tierkloof and its surrounds have not been used for farming purposes for many decades and the terrain has long since recovered to its original pristine natural condition.
Ironically, despite its dry climate, the area is blessed with a significant amount of clean sub-surface water. This aquifer is relatively close to the surface, as evidenced by the common occurrence of natural springs as well as the abundance of productive boreholes. Thus despite the absence of flowing rivers or reliable precipitation, today there is more than sufficient pure water available to satisfy basic needs and even low-intensity irrigation farming - particularly at the base of the Swartruggens mountains.