An Introduction to Karoo Geology

Discovering what’s great about the Great Karoo

Dr John Almond
Natura Viva cc, CAPE TOWN  (naturaviva@universe.co.za)

Look at any decent map of South Africa, or fly across it, and there’s no missing the impressive, arid expanse of the Great Karoo. But missing out the Great Karoo is precisely what so many South African travellers aim to achieve (let alone most poorly informed foreign visitors).  What a tragic omission! Here in the vast but somehow hidden heart of the country are found some of South Africa’s most archetypal landscapes – her flat-topped koppies and rolling vlaktes clothed with scrubby bossieveld, her rocky valleys and dry riverbeds lined with acacias, alive with birdsong and the sensual throb of horny insects.  

Commonly dismissed by the unknowing as “hot, flat and boring”, to the discerning traveller the Great Karoo is, more often than not, nothing of the sort.  With its countless rocky outcrops and exquisitely preserved fossils, the region provides an ideal outdoor classroom for those interested in the deep history of Life and Earth.  One hundred million years of geological time are recorded here by a succession of ancient sediments some ten kilometres thick!  Geologists can trace the paths of 300 million-year-old ice sheets, followed by cool southern seas where early aquatic reptiles frolicked and fished.  The Karoo is famous among palaeontologists for its abundant remains of terrestrial vertebrates from the Permian Period (about 255 million years ago) whose petrified skulls and bones litter the rocky slopes of many a lonely koppie.  Among these marvellous extinct beasts were fearsome, sabre-toothed predators and lumbering, dim-witted plant-eaters that lived 30 million years or more before the first dinosaurs. They included the direct ancestors of modern crocodiles, turtles and mammals, and probably ours too!  Accumulations of carefully crafted stone tools bear witness to Stone Age human occupants of the Karoo margins stretching back a million years or more.

Lions, hyaenas, wild dogs, elephant, black rhino and even hippos thrived here into historical times. Indeed, until recently the Karoo supported the largest wild herds ever recorded anywhere in the world - the great trekbokken migrations of springbok and other mammals which finally ebbed away in the late nineteenth century.  Happily, many of these noble animals are being reintroduced into state and private conservation areas, while a wide range of other fauna – from the implausible aardvark to a wealth of elusive desert birds and jewel-like goggas – remain to delight the inquisitive naturalist. 

Equally special (and under-appreciated) is the wonderful variety of resilient Karoo plants that have successfully adapted to their challenging semi-desert environment. They range from juicy vetplante or succulents nestled in the shade of nursery bushes to ancient, gnarled bossies, dwarf bulbs and even delicate mosses and ferns. Between them they have evolved a multitude of ingenious tricks to conserve water, escape the searing summer sun, avoid the attentions of browsing animals as well as to co-opt wind, water and wildlife to spread their pollen and seed across the vlaktes.  To add to their seductive charm, many Karoo plants enjoy earthy Afrikaans names ranging from the shamelessly erotic to the frankly outrageous. 

The Great Karoo is a vast but strangely secret place of concealed wonders waiting to delight the curious, reward the patient, and soothe the city-fevered brain.  After a great day rambling through the veld, how delightful it is to relax, glass in hand, as the late afternoon sun glows warmly upon rugged krans and koppie.  Where better to rediscover the breathtaking beauty of our home galaxy, scattered across a tremendous Karoo night sky? Take time to explore a small patch of the true heartland of South Africa, and there’s a fair chance you’ll start missing the Great Karoo before you’ve even left!

(This article appered in the Overberger Feb/Mar 2006)

 

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