We had a very succesful trip about a month ago when we journeyed with Roger and Pat de la Harpe to Bonamanzi Game Reserve, and then through to Clarens to scout out venues for various workshops. Bonamanzi is located right on the shores of Lake St Lucia and the World Heritage Site of Isimangaliso forms their northern boundary, so they are perfectly positioned in terms of birding, photographic and drawing and painting safaris. The views out of what is the largest wetland in Africa are phenomenal, and then there are the delights of the reserve itself. Accommodation comprises delightful, air conditioned thatched chalets, all with en-suite bathrooms, set in beautiful, thorn tree studded parkland with warthog and nyala wandering freely through the camp. Some of the classes will be held in a beautiful, semi-enclosed deck overlooking an African waterhole where the water lilies splash their colour across the languid waters and frogs serenade one another late into the night.



Dinners are served beneath the star-studded heavens, where cathedrals of candles and a huge camp fire throw flickering, golden shadows across enchanted faces. Delicious food, chilled drinks and convivial company are a given, and time is marked by the slow wheel of the Southern Cross through the African sky.

We reluctantly left Bonamanzi and headed inland to the second highest town in South Africa - Clarens. Again a very successful couple of days, for we found dinosaur remains, explored the Golden Gate National Park from a geological point of view and looked into the possibility of taking participants over the highest road in Africa to the Letseng Diamond Mine. Letseng is the highest diamond mine on Earth and has produced four of the twenty largest diamonds ever discovered.

We approached the mine to ask them if they would take tours and they have agreed to do this, so this is a huge feather in Old Canvas Expeditions' cap, and an exciting addition to our workshop. We have also organised flights along the Eastern Escarpment to take in the second highest waterfall in Earth - the Tugela Falls - the towering buttresses of the Drakensberg/uKhahlamba World Heritage Site, and the vast Post Gondwana Landscape which stretches out to the east.

Certainly experiences not to be missed and we would urge everyone to come on one of our safaris. As we say, more than just a game drive. Go to www.oldcanvasexpeditions.com for more information.

Romancing the Stone Workshop

Well, it has been a long hard slog but we have managed to break the back of it. Yesterday we went live with our new website, www.oldcanvasexpeditions.com. Now Old Canvas is the provider of some of the top specialist safaris in Southern Africa. More than just a game drive is our slogan and that is exactly what we hope to achieve.

Old Canvas Expedition's flagship geology workshop is out of the town of Clarens in the Eastern Free State - at an altitude of 1800 metres it is the second highest town in the country. The beautiful sandstone cliffs which surround the town and provide the magnificent backdrops for which it is famous, are fossilised sand dunes, harking back to a time 180 million years ago when the area was a desert, the realm of dinosaurs and small mammals.

Gondwana was stilled joined; a vast supercontinent including Africa, India, Australia, Antarctica and South America. Incontestable forces began to play out at the end of Gondwana times, and the supercontinent began to tear itself apart. As these ruptures took place, thousands of metres of red hot, incandescent lavas flooded out onto the Gondwana landscape, burying all in a fiery embrace.

Walking through the town of Clarens gives no inkling of this cataclysmic history, but looking south one can see the blue Maluti Mountains - a remnant of those thousands of metres of lava which burned everything before it. Dinosaur bones protrude out of rocky road cuttings, the ancient desert dunes lie preserved in the cliff faces, faults form large dislocations in Earth's crust and dykes traverse the landscape for tens of kilometres, once feeder pipes to the overlying basaltic outpourings.

We will marvel at the geological history of the region and the story of both wandering continents and wandering dinosaurs. We will drive the highest road in Africa to the Letseng Diamond Mine - the highest on Earth and the source of 4 of the 20 largest diamonds ever found. On the final day we will fly past the Tugela Falls, the second highest on Earth at 947 metres and enjoy views of the Drakensberg. This range is a proclaimed World Heritage Site - the uKhahlamba. From the air we will also be able to see the post-Gondwana landscape and the phenomenal gorges that the eastward-flowing rivers have cut into the ancient African bedrock.

Join us then on a journey through 300 million years of Earth history, witness the breakup of Gondwana, the outpourings of lava and see the highest diamond mine on Earth. Perhaps the highlight will be to fly along the Eastern Escarpment past the Tugela Falls and the towering ramparts of the Drakensberg.

These are experiences which cannot be missed, and so we invite you to journey not only to one of the most picturesque towns in South Africa with its art galleries and restaurants, but on a journey down through the aeons, to a time when dinosaurs once ruled the Earth and Clarens was at the heart of a vast continent called Gondwana.

Reptiles of the Great Karoo

Fifty million years on, and the Karoo Sea is but a hint of its former self. In its place is a giant lake fed by a number of northward flowing rivers draining from the high Cape Mountains which shimmer through the heat haze far to the south. Along the river banks vegetation grows in abundance thanks to a plentiful supply of silt, water and the hot climate. On the flood plains between the rivers vegetation still grows abundantly although not with the same profusion of that along the river banks. Vegetation comprises mosses, ferns, glossopterids and gymnosperms which grow in profusion along the river channels, while in the more arid flood plains, more glossopterids and gymnosperms dominate. For the most part the rivers remain confined to their channels, but during the wetter, winter months when torrential rains lash the high Cape peaks to the south, the rivers rise and overflow onto the low-lying plains in an all encompassing flood, bringing water and nourishment to the arid areas between the rivers. Insects and beetles rattle through the undergrowth while cockroaches scratch in the leaf mould. And where there was little animal life in this ancient world until now, things have changed, for rooting between the plants and wading in the shallows are herds of strange creatures with shovel-like heads and tusks protruding downwards from the rear of their mouths. This is Lystrosaurus, a beast with a long robust body and short legs - a clumsy and inelegant creature. They wade and forage, chomping their way through vast amounts of vegetation while some work their shovel-like heads as spades, burrowing into the river banks to make shelters from a hostile world.

Gondwana has continued its inexorable wanderings from the southern high latitudes to warmer climes. Ongoing sedimentation over millions of years has filled the Karoo Sea to the extent that only a large lake remains, fringed with primitive vegetation. The Cargonian highlands to the north have been eroded down and become covered by younger sediments of the Karoo Basin. The only significant topography now comprises the Cape Mountains far to the south, which due to the ongoing processes of erosion have produced billions of tonnes of sediment which has filled the basin. Fossil trees show growth rings which indicate changing seasons and possible droughts. Desert roses, so typical of arid conditions, are found within the fossil sands of the Beaufort Group. The flood plains are home to a passing parade of reptiles which are the forerunners of the dinosaurs and ultimately mammal life, and Lystrosaurus but a latecomer on the stage of reptile evolution. One of the most amazing things about the rocks of the Karoo Supergroup are their level of preservation. Often rocks of this age get caught up in the tectonic mill, or are subject to erosion which destroys the record of Earth history which is written therein. The Karoo is internationally famous in palaeontological circles for its abundance of pre-dinosaur fossils. They preserve an almost unbroken record of 80 million years of vertebrate evolution and record the progression of life from primitive reptiles to the transitional stage between reptiles and mammals. These rocks also record the largest extinction event which has ever occurred in the history of life. The end Cretaceous extinction which led to the demise of the dinosaurs is more famous, thanks to popular movies and media coverage, but was nothing compared to the end-Permian event which shook the very foundations of life, when an estimated 96 percent of all life was extinguished. This event took place 251 million years ago and no one has yet come up with a watertight theory as to the reasons for this extinction, but changes in Earth’s atmosphere due to volcanic activity, a major meteorite impact, or drop in sea levels due to an ice age which exposed organic sediments leading to sudden oxygen depletion of the atmosphere have been postulated. For whatever reason, life was almost snuffed out. No longer was there any vegetation to slow the transport of sediment and the meandering rivers which fed our great lake were replaced by a myriad of sand-laden drainage channels which spread over the flood plains. Lystrosaurus survived the extinction event and not only are its remains found in the rocks of the Karoo, but also in Antarctica, additional evidence for the great landmass of Gondwana. Ongoing northward drift of Gondwana led to increasingly arid conditions. Local swamps were scattered here and there, but over time a vast desert formed in the centre of Gondwana, far from the oceans and possibly in the rain shadow of the towering Cape Mountains. Massive sand dunes formed which are now preserved as the golden cliffs of the Clarens Formation, so spectacularly displayed as the little Berg and at the Golden Gate National Park.

We are currently putting together a fortnightly news letter on all things geological, so if you wish to subscribe please email me on geologist@netactive.co.za

The Karoo Sea

This is swampland on a giant scale. Teaming, pushing, living, scrambling forest grows riotously along the muddy banks of lagoons and stinking back swamps. Trees, club mosses, cycads and ferns compete for space, water and light, while those that have seen their days out collapse back exhausted to the forest floor, to be rapidly colonised by fungi and bacteria. Beetles scramble through the leaf litter or fly ungainly through the canopy, while cockroaches scuttle and scratch in the leaf mould. In the creeks and backwaters amphibians populate the mud flats and dark pools, while out on the sunny waterways fish leap and squadrons of giant dragonflies keep station above the languid waters.

Times have clearly moved on from the icy grip of the Dwyka Ice Age. Gondwana has wandered northwards and South Africa now finds itself at approximately 30° south where temperatures are more conducive to life, which has seized the day, colonising the land to form vast subtropical forests along the northern rim of an ancient sea. But now we need to step back a little and look at the geological processes which have led to this change of circumstances. We have looked at the great ice age known as the Dwyka glaciation of 300 million years ago, but now we must take our focus off KwaZulu Natal for a short time and look at what was going on in South Africa as a whole. Many of us will have travelled through the passes of the Cape Mountains and wondered at the spectacular folding which characterise this mountain chain. These mountains began to form approximately 330 million years ago during the late stages of the Dwyka glaciation. The mountains formed the southern boundary of an ancient sea which covered the majority of Southern Africa – bearing in mind of course that we were part of a larger supercontinent. This sea had a low tidal range and is thought to resemble the modern Black Sea - open to the larger ocean, but without the dynamics of a full-blown ocean. To the north, stretching from the Northern Cape through Gauteng to Mpumalanga, were the Cargonian Highlands – a range of hills which defined the northern limits of this sea. Our Dwyka ice sheets have been bumping and grinding their way southward across these northern highlands before being cast adrift as icebergs on the turbulent waters. As the ice scoured the landscape, Gondwana continued to drift northwards, ultimately bringing us to warmer latitudes and creating conditions conducive for the burgeoning of life.

With decreasing latitude, the ice melted, to be replaced by southward flowing rivers which began to drain the Cargonian highlands, depositing vast quantities of sediment along the northern margins of the Karoo Sea to form large, meandering deltas. Like deltas everywhere, they supported the forests and swamp life where today’s narrative began. The trees that dominated these deltas were a Gondwana classic known as Glossopteris - the distribution of this species another nail in the coffin for the naysayers of continental drift and plate tectonics – it is found in South America, South Africa, Australia, India and Antarctica, strong evidence indeed for the supercontinent of Gondwana. Glossopteris, ferns, horsetails and club mosses thrived within these vast deltas, to the extent that thick accumulations of wood and organic matter were unable to rot and were buried and ultimately converted to coal. These deposits form our coal reserves of KwaZulu-Natal and the Highveld.

The southern margins of the Karoo Sea were characterised by deep water and a narrow littoral, set against the towering peaks of the Cape Mountains. Small, fast flowing rivers typical of mountainous regions deposited their load along a narrow littoral on the southern margin of the Karoo Sea. Every so often some of this accumulation of sediments would slump into the depths to form large, fan like deposits on the sea floor called turbidites, and these may still be seen fossilised in the hills of the Eastern Cape. But this is treatise on the local geology, so we will stay focussed on what is in our backyard. The accumulation of sediment in the Karoo Sea continued for in excess of 150 million years, eventually filling the basin. Karoo rocks have the widest distribution across the subcontinent and reflect the changing latitude and depositional environments as the basin began to fill. It is an ongoing tail of evolution and change and we will continue with the Karoo story in the next article. However any journey inland from Pietermaritzburg will traverse sediments once laid down either on an ancient sea floor or on the swampy margins thereof, where verdant forests thrived in a magnificent outburst of life. Karoo rocks extend to the crest of van Reenen’s Pass and beyond – a truly magnificent heap of sediment which reflects in part the geological history of a subcontinent.

A Grue of Ice

Glacial Striations - Hopewell Farm, KZN

From Zululand in the north to the shores of the Southern Cape in the south are to be found accumulations of a fine grained, bluish grey rock containing ground down lumps of granite, sandstone and other rocky debris. This might all seem esoteric and of little relevance to us, but perhaps if I were to tell you that these piles of bluish-grey rock represent nothing less than fossilised deposits of glacial till, perhaps you might sit up and take notice. Glaciers? In Africa? Well yes, but not last week, not last century, but 300 million years ago. At that time we were still part of the supercontinent of Gondwana, drifting through the polar-regions, with conditions not much different to those which Antarctica is currently experiencing.

However, no one was around then to observe this, so what evidence is there to prove that we were in the grip of prehistoric ice age? Many of the geologists who mapped the strata of South Africa a hundred years back were from European schools and hence were familiar with modern glacial tills which occur in northern Europe. The effects of the inexorable milling of the landscape by ice sheets during the last European ice age are no different to those experienced here 300 million years ago, except that our deposits have had time to consolidate and lithify. I would imagine that they were more than a little surprised to find evidence of glaciation whilst sweltering under the African sun. At that time there was no mechanism to explain to our pioneering geologists how the climate got to be so cold, but there was no refuting the evidence. We have the benefit of hindsight now that the theory of continental drift has become hard geological fact, but back then the very idea of wandering continents had not even been suggested. To have put forward a crackpot theory that the immovable earth had been part of a larger ancient continent, and moreover that this continent had once been centred on the South Pole would have led to derisive laughter at best or questions as to the state of their sanity at worst.

The fine-grained groundmass which makes up the bulk of the rock is fossilised rock flour – a pulverised matrix ground into being by the overbearing weight of tonnes of ice juddering across the ancient continental surface. Our local outcrops of Dwyka Tillite contain countless millions of fragments of Natal Group Sandstone and Granite Gneiss, torn from the underlying substrate by the bulldozing and grinding ice.

Perhaps even more spectacular are the occurrences of striated pavements in a number of places around the province. When they opened up the foundations for the new Geography building at the then University of Durban-Westville, they found a striated pavement with grooves gouged into the hard underlying sandstone - grooves made by the bedload of the glacier as it ground its way across the sandstone substrate. Other local examples occur on top of the Natal Table Mountain and on the Hopewell Farm near Thornville. Dropstones – boulders rafted out on ice floes and then deposited into the sea floor muds - can be seen in the road cuttings on the Table Mountain – Nagle Dam Road.

So much for the direct evidence of glaciation, the question now remains as to how they worked out that Southern Africa was drifting around down there in the high latitudes. Well, it was found that, as lavas pour out onto Earth’s surface, which they have been doing for 4.6 billion years, the iron in their minerals aligns itself with the prevailing magnetic poles. As the rock cools the iron is frozen into that orientation and preserved for geophysicists to analyse millions of years later. Some of you might have noticed when driving up Sani Pass, round uniform holes drilled in the lavas in the road cuttings, evidence that the geophysicists have been there before you. Careful note is taken of the orientation of the sample in the field before it is removed from outcrop. Back in the laboratory the specimen is then reorientated to its original field position, and then the orientation of the iron is measured. This then tells our geophysicist in which direction the magnetic pole once lay, relative to our rock sample. Thousands of these measurements have been plotted onto base maps, and over time a pattern has emerged polar wanderings throughout Earth history.

So on a continental scale, vast ice lobes ground southwards across the ancient face of our continent, scarring and adding character to our African landscape. Vast deposits of tillite may be seen from the Dwyka River in the Cape to the far north of Zululand and are evidence of continental wanderings and an ice age which has us in its frigid grip 300 million years ago.