Tswaing Meteor Crater

Tswaing Crater seen from the rim. The rim is about 100 metres above the bottom of the crater. Inside is saline water, in the past soda and salt were extracted from the crater. The ruins of the factory and associated operations can be seen around the area. Tools from the middle stone age show that people have been coming to the crater for at least 100 000 years.

“The shockwave through the ground would have been equivalent to a major earthquake, but the air blast and associated impact debris would have done most of the damage. Loose rocks, debris from buildings, cars and even trees would have become lethal projectiles and within a radius of 50 km around the site all life would have been destroyed”. [1]

This is how McCarthy and Rubridge (2005) describe the impact of something the size of the object that hit the earth near Pretoria 200 000 years ago would be like. The devastation caused by something like that today would be catastrophic. Yet major impacts on earth are relatively common. Since 2000 there have been at least eight widely reported impact events. The most recent was Chelyabinsk meteor which exploded over Russia in February 2013. This was well documented and footage can be seen here.

Inside the crater the slopes are dominated by Vachellia robusta and Combretum trees. Creating a good habitat for birds and other animals that favour woodland environments.

From inside the crater one is struck by the roundness of the rim.

McCarthy and Rubridge Break down the estimates of how often impact events of different magnitudes take place. Every 100 million (10⁸) years an impact leading to global mass extinction occurs. Smaller events causing craters 20-50km in diameter occur once every 500 000 years and even smaller events, like the one that caused the Tswaing Crater occur as often as one to three times per hundred years.[2] These kind of numbers really bring ones tentative place on earth into perspective. The Hollywood version would have a hero going up into space and somehow stopping the massive body from colliding with the earth, but that is a fantasy. A meteor the size of the one that created the Vredefort Dome in South Africa would not be stopped and impact and extinction would be unavoidable.

A satellite image of Tswaing Crater. The urban sprawl is beginning to encroach on the crater.

But what will be will be and the event that happened 200 000 years ago left a remarkable crater and the surrounding environment has become Tswaing Meteor Crater Nature Reserve. The reserve is surrounded by urban sprawl, but is a refuge for some wildlife that would otherwise have nowhere else to go. It is also a good birding area, I have observed: Green-backed Herons, Magpie Shrikes, Temnick's Courser, Wattled Starling, African Hawk-Eagles, Red-billed Hornbills, Yellow-Billed Hornbills and African Grey Hornbills.

There are many Variable Skinks (Trachylepis varia) moving around in the leaf litter around the crater.

On a single small tree (Combretum molle), without looking too hard I found three different insects all apparently feeding on the new growth of the tree. 

Velvet Bush Willow (Combretum molle). On this small tree I found three different types of insects just by quickly scanning what was moving around. With a bit more effort I am sure I could have found more than three times that amount.

Fruit chafers (Pedinorrhina trivittata) clambering on a branch.

Another fruit chafer but a different species (Clinteroides permutans).

This Polyrhachis ant was busy feeding on a broken tip of a new shoot.

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[1] McCarthy, T and Rubridge, B. 2005. The Story of Earth & Life: a southern African perspective on a 4.6-billion-year journey. Random House Struik: Cape Town (305-306).

[2] McCarthy, T and Rubridge, B. 2005. The Story of Earth & Life: a southern African perspective on a 4.6-billion-year journey. Random House Struik: Cape Town (306).

Spring 2013 – Venda, Limpopo Provence and the Makuleke/Pafuri Area Kruger National Park

I was fortunate enough to spend the spring of this year in the far north-eastern region of South Africa. Leaving Johannesburg on a somewhat chilly Thursday morning, I drove up towards my first destination Gundani camp site deep in the heart of Venda. I arrived in the dark and after trying to get into what I thought was the campsite (it turned out to be the cemetery) and walking around the village trying to find someone willing to help me I was shown where the site was.

Miombo Woodland in Gundani, Venda. This is the only patch of Brachystegia woodland in South Africa, making it a rare ecological area. The characteristic The golden and red shades to the leaves are characteristic of this type of woodland.

The reason I chose to make a stop at Gundani was because it is the only patch of Miombo Woodland in South Africa. I hoped to explore the biodiversity of the area but there was no water and I was not prepared. So after I took a short walk, I decided to drive and find a place that offers camping and water.

Variable Skink, Trachylepis varia. These widespread skinks are often very common. Interestingly they have been known to lay eggs in part of their range while in other parts of the range they give birth to live young.

The next place I stopped at was Nwanedi Nature Reserve. The reserve encompasses about 11 000 hectares and includes the foothills of the Soutpansberg Mountain Range.  There are also two dams on the nature reserve and the dam walls are very close to one another (500 metres or so). The campsite was full of life with many Baboons, Vervet Monkeys and Banded Mongooses. I spent two nights in this reserve and had a whole day to hike. I chose to explore the koppies and got my first close encounter with the vegetation I was to encounter in the Limpopo Basin.

Baobab Tree, Adansonia digitata, through an ongoing effort on the part of eco-tourism marketing people, the Baobab has become iconic of Africa. Many people don't know that both Madagascar and Australia have their own species of Baobabs. This points to the ancient ancestry of the tree they developed before the continents drifted apart, and to their emergence on the continent of Gondwana.

The most striking tree in the area is the mighty Baobab Tree, Adansonia digitata. I have seen Baobab trees before, but have never been in an environment where they are as prominent. In this far northern corner of the Limpopo Provence there are many Baobabs jutting out of the ground and raising their root-like branches high into the air.

The age of baobab trees seems to be a contentious issue. Some sources claim that there are individual trees over 3 000 years old, while others see them as 1 000 years old. When standing next to one of these trees one gets the feeling that they are ancient. I would not be surprised if they did turn out to be amongst the oldest organisms on earth.

Another striking tree that grows in the rocky areas of the Limpopo Basin is Commiphora marlothii. These trees have peeling yellow bark that reveal a trunk that is green. There is a theory that some trees have evolved this paper-thin peeling bark in a response to parasites such as mistletoe. The mistletoe seeds are not able to get a hold on the tree for long enough to send a root into the bark as the continuous peeling causes the seeds to fall off.

The peeling bark of Commiphora marlothii diagnostic in this species.

In the dry season these trees stand bare and are a very striking contrast to the subdued colours of the rocks.

Another tree, superficially similar to both the Baobab and the Commiphora marlothii is Sterculia rogersii the Lowveld Star Chestnut. These trees have an orange tinge to the bark and also express the peeling adaption of the Commiphora. All three trees are adapted to a life of long dry periods on the well-drained mountain slopes.

In areas without elephants Sterculia rogersii, the Lowveld Star Chestnut grows out in the open and is very common. Elephants eat this tree wherever they can find them and in areas with elephants these trees are limited to areas where they can be protected by rocks.

The bark of these trees is superficially similar to the bark of Commiphora species.

The small flowers of Sterculia rogersii grow straight off the trunk and branches of the tree and stand out nicely against the bark. The name "Sterculia" is derived from the roman god of god of manure. The flowers have a rather pungent smell.

At night I looked around the area for some of the small things and came across some interesting creatures, some new and others familiar.

Giant Assassin (Platymeris). These are big assassin bugs. They are slow moving while hunting, but can move fast when disturbed. I have heard that they can inflict a very painful bite. 

The Giant Assassin is host to small parasites. I think they are members of the Trombidiidae family.

This small Leaf Rolling Cricket (Gryllacrididae) was moving around on the grass.

This cockroach (Blattodea) has an exposed tergal gland which emits a hormone that attract females.

Turner's Tubercled Gecko (Chondrodactylus turneri) is common throughout the Limpopo Basin. I see many of these and they are really a joy to photograph when they do stay still.

Leaving Nwanedi Nature Reserve, I drove east towards the Kruger National Park. This was the reason I was up in the north-western part of Limpopo Province; I was to spend the rest of the month doing training in the Makuleke/Pafuri area. Everyday was spent walking and learning about ecology, dangerous game, birds and plants of the area. 

The camp I stayed in was about three kilometers from the Limpopo River, bordering Zimbabwe to the north. In the east was Mozambique. The Makuleke concession belongs to the Makuleke people who used to inhabit the area until the 60s when they were forced out by the police when the area was incorporated into the Kruger National Park. The Makulekes filed a land claim and won the land back. They now own the land, but have entered into an agreement with Kruger National Park for the continued management of the land.   

The Makuleke area can be broadly divided into four types of habitats: Floodplains dominated by Northern Lala Palm (Hyphaene petersiana) thickets; Forests dominated by Fever Trees (Vachellia xanthoploea); Rocky scrubland dominated by thorn trees (Vachellia and Gynosporia species) and Baobabs (Adansonia digitata)and Koppies that are covered by stands of Lembobo Iron Woods (Androstachys johnsonii).

This is a typical view of the Limpopo Flood Plain, the area is sandy and dominated by Northern Lala Palm thickets (Hyphaene petersiana).

This composite image portrays the Fever Tree, Vachellia xanthophloea. These trees dominate the forested areas. The green of the bark lends a strange quality to the light in the forest. 

The scrubby high lying areas of the Makuleke/Pafuri area are bushy and sandy. Baobabs sprout out of the earth and between them there are Impala Lilys (Adenium multiflorum) which are also adapted to the dry conditions.

In the koppies in the Makuleke area Lembobo Ironwood trees (Androstachys johnsonii) are common and tend to grow in dense stands.

The Makuleke area is one of the most beautiful regions I have ever visited. Along the Limpopo there are forests of fever trees with an undergrowth of fragrant Dwarf Sage (Litogyne gariepina), in the expansive flood plains there are thickets of Northern Lala Palms and slightly higher on the rocky ridges there are clusters of Baobabs growing out of the basalt. A little higher on the slopes are the endless Mopane woodlands. These are the predominant areas and their associated plants, between them are many different species growing.

The striking Combretum microphyllum added to the beauty of the area, these plants were flowering everywhere giving a red blanket to the dense greenery in the lush areas.

African Harrier-Hawk being mobbed by African Palm-Swifts. These birds are ferocious predators, I have been lucky enough to see one move from tree to tree in search of bird nests. They move methodically up the trunk and once they reach the top they fly to the next tree and repeat this until they find a nest.

Bush Pig skulls, pictured here, can be differentiated from Warthog skull by the the large tushes on the lower jaw and the heavy glandular area in the top of the snout.

The Black-Backed Jackal, one of Africa's most successful and widespread carnivores. Jackals often supplement their meat diet with fruit.

One night we saw a leopard make a kill. There was a group of impala in the road one night on the way home after a walk. We turned off the headlights to allow them to move off without being dazed, when we turned the lights back on we saw a leopard run across the road toward the group of impala. The next thing it was back on the side of the road it had come from and was in the process of killing an impala. It all happened very fast.

The area has a lot of game. There are many Impala, Nyala, Kudu, Eland, Buffalo and Elephant. There are also Bushpigs, Leopards, Sharpe’s Grysbok, Warthog, Thick-Tailed Bush Babies, Baboons and Vervet Monkeys. The area is also very famous for its birding, there are some very special birds in the area and among those I saw Racket-tailed Rollers, Black-throated Wattle-eyes, Lemon-breasted Canary, Meve’s Starling, Pel’s Fishing Owl, White Crowned Lapwing, Green-capped Eremomela, Grey-headed Parrot, and Senegal Coucal.

A pair of Racket-tailed Rollers. These birds just enter South Africa in the Makuleke area and are one of the specials of the area. We saw quite a few of these birds up there.

A view of a clearing in the forest. The forest was a enchanting place to walk, all around birds would call and butterfly would drift by in masses. There was also an abundance of animals in these forests.

An elephant in the forest feeding on the leaves of a fever tree (Vachellia xanthophloea).

Walking everyday, one gets a very different bush experience than one would on a vehicle. You get closer to nature as you are immersed in it, thus increasing the intensity and the tempo in which you experience everything is much slower. The aims of our walks were to explore this wilderness area, learn as we walked and achieve non-dangerous encounters with dangerous animals.

The sight of buffaloes in the long grass has got to be one of the better ways to start off a day. These animals are huge and can be dangerous if they are not given their room.

We encountered this buffalo while on a walk in some long grass. The buffalo was coming up toward us on the path. The wind was in our favour and we managed to move onto a ridge just above the path and viewed it as it walked into our scent. Immediately it's body language changed and it began to look for us with malicious intent. We were safe however crouched up on the ridge in silence. 

We had many “dangerous game encounters”. There were many Buffalo encounters and many elephant encounters. Some of the encounters were fleeting, while others were experiences that I will never forget. When a full-grown bull Elephant comes over to you and decides to take a closer look there is a moment of intensity and paradoxically, calm. Time seems to stretch and you are brought down the same level as the animal – an animal among animals.

We encountered this elephant some distance away, at first it turned its back on us and walked away, we decided to walk in front of it to see if it would follow us and it did. We led it all the way to a ridge and it gave us a bit of a show by reaching up to this tree and then moved on.

One of the more interesting encounters we had with an elephant was with this dead bull. The elephant died in the middle of a popular gorge that we walked. There were many vultures feeding on it and it was full of maggots and beetles. To this animal just lying there and being decomposed and cleaned up by tiny maggots was very interesting. To see something as massive as this returning to the earth and back into the energy cycle was really thought-provoking. Everything moves through its life consuming and absorbing energy, only to pass it on when it dies.

This elephant died of natural causes, it was already a few days old and in a advanced state of decomposition. The white stains are where the vultures have defecated. The trunk has been dragged about fifty metres away.

Blowflies of the Calliphoridae family feeding on the elephant carcass.

Another animal that we encountered was White Rhino. We were walking and saw them grazing in a thicket. We sat in the shade of a tree and waited for them to come out and they did. We sat there for about an hour watching the rhino, which were 30 metres away from us and unaware of our presence. We managed to move out of the sighting and did this without the animals becoming aware of us: A perfect encounter.

Once a common sight. Seeing Rhino on foot is becoming increasingly more difficult due to the declining populations. There were two rhinos at this sighting. The last two in the area. Both were males, so even if these two somehow escaped being poached, they would still be a stagnant population. 

As I write this I wonder if those two rhinoceroses are still there? The amount of money that can be gained from supplying information on whereabouts of a rhinoceros is around R 10 000. The price of the horn is another story. At the moment, rhino horn is said to be the most expensive product on earth.

An increasingly common sight. Rhino skull with horn removed. One can see how the animal was cut right deep in the face to remove the horn and surrounding bone. Grim business.

In this image you can clearly see the vertical chop by a panga and then the clean horizontal cut made by a hacksaw to remove the horn. The poachers get to work so fast to make an escape that the animal was in all likelihood still alive when they left the scene. 

In addition to the abundant big game animals in the area, there was a multitude of smaller animals. The October rain’s had not yet arrived and I got the impression that nature was just waiting to explode with renewed vitality. A few days before I left there was a small amount of rain and immediately after that the amount of invertebrates increased dramatically.

Scolopendromorpha centipede. These were very big and were often seen hunting at night.

Other active night hunters were these large Ground Beetles (Thermophilum).

The Armoured Ground Cricket, Enyaliopsis transvaalensis. At certain times of year this species emerges en masse and although they are generally herbivorous, they will often become cannibals, eating other Armoured Ground Crickets that have been squashed. However, at the end of the dry season, this was the only one I saw.

Striped crickets from the Gryllidae family are abundant in the Makuleke area. They are very striking with their black and white patterning.

These small Hister Beetles (Histeridae) dotted the paths at night. These beetles are predators and there are said to be around 4 000 species worldwide.

Large Copper Dung Beetle (Kheper nigroaneus). Dung Beetles are said to navigate and orientate themselves using the Milky Way (click here to find out more).

This assasin (Acanthaspis species) uses debris to disguise itself to blend into its surroundings. I only noticed them when they moved and it really did look like moving dirt.

A Hemiptera nymph mimicking an ant, this animal is using the aggressiveness of ants to its own advantage.

This assassin of the Rhaphidosoma genus mimics grass. 

The trumpet-shaped waxy entrance to a Mopane Bee Hive. The resinous wax deters insects that may raid the nest.

Mopane Bees (Meliponula) in the tube of their hive. It is said that Mopane Bee Honey is very tasty and well worth the effort of getting out the tree. The bees are also stingless.

Spider Hunting Wasp (Pompilidae) dragging its quarry to a burrow where it will be paralysed, have an egg layed on it and finally it will be entombed: food for the growing larva.

As far as reptiles go, the area has many specials. I was lucky enough to find one of these specials: The Zimbabwe Flat Gecko (Afroedura transvaalica), also known as the Transvaal Flat Gecko. I found the gecko on a rocky ridge on the western side of the park. The park also boasts a record of a Forest Cobras (Naja melanoleuca) along the riverine forests of the Limpopo. This record is well documented.

One of the highlights of my trip was finding this Afroedura transvaalica or Transvaal Flat Gecko or Zimbabwe Flat Gecko. The one pictured here is a juvenile.

While I was in the area, the most common reptiles were Variable Skink, Eastern Striped Skink, Cape Dwarf Gecko, Tropical House Geckos (these really seem to be everywhere), Rock Monitors and Crocodiles. I was also lucky enough to see a Western Stripe-bellied Sand Snake eat a skink, a python and a very lightly coloured juvenile (+/- 1.8m) Black Mamba in a tree. I was unable to get a photograph as the sun was behind the snake. I did spend a long time watching it and I must say that there is something so special about seeing a Black Mamba in the wild. They are such amazing and misunderstood snakes.

Eastern Striped Skink, Trachylepis striata is common in the lowveld. These generally inhabit trees, but they have also adapted to living in and around tents and other structures in the bush.

Natal Rock Python (Python natalensis) is one of the larger reptilian predators in the area. This individual was in a small shrub and perfectly camoflauged. I'd say it was between 2.5 and 2.8 metres long.

I was lucky enough to see this Western Stripe-bellied Sandsnake (Psammophis subtaeniatus) make a meal of a Variable Skink (Trachylepis varia). After consuming the skink, the snake continued hunting and was not at all phased by my presence. It came within a half a metre of where I was sitting as it moved through the leaves looking for another skink.

In anticipation of the rain and the upcomming breeding season, this Eastern Olive Toad (Amietophrynus garmani) was full of eggs. Between 10 000 and 25 000 eggs can be laid at a time.

This big Rock Monitor (Varanus albigularis) came through the camp hunting one day. It was seen a few times and was not concerned at all about human presence.

Another Turner's Tubercled Gecko (Chondrodactylus turneri). This one posed very nicely. These geckos get big.

A Cape Dwarf Gecko (Lygodactylus capensis). These small widespread geckos are diurnal.

A Worm Snake or Thread Snake (Leptotyphlops). These small burrowing snakes are completely blind and adapted to a life underground where they feed on the eggs and larvae of termites and ants. It is very difficult to tell the species apart from one another using images alone.

The Limpopo river and the Limpopo Basin is a good area for crocodiles. This is a "small" Nile Crocodile (Crocodylus niloticus) of about two metres. The Nile Crocodile is arguably Africa's most dangerous animal.

While walking in the Kruger National Park, one encounters some strange things. One day while walking from the eastern side to the west we came across what we initially thought was an old Makuleke homestead. We uncovered it and it turned out to be a memorial to a certain Cezani Piet Rose. Finding this memorial in the middle of the Limpopo Floodplain was one thing, but then it struck us that the day of the man’s burial and the erection of the memorial were exactly to the very day 63 years and 8 years ago. What are the odds of finding something like that when walking in the wilderness? There was some speculation of the meaning of this encounter. Some people thought it was fate, some ventured that the universe was sending a message to us. I however, am of the opinion that the universe is cold and dead, and that what we encountered was a meaningless coincidence: dwarfed by the coincidence that I am alive and able to think about coincidences at all. But none the less, this was a very remarkable thing to find.

The memorial we found on one of our walks in the middle of nowhere. Sixty Three years ago to the very day this man died. Who he was or what he did is still a mystery.

Being the end of the dry season the area was relatively parched. There must have been a lot of groundwater however as many of the areas were still green. While I was there we saw some of the pans dry up. As they dry, storks and eagles arrive to pick of the fish that are slowly becoming exposes. These drying pans also become concentrated sources of another killer in the area: anthrax (Bacillus anthracis). In areas like this anthrax really begins to take its toll at the end of the dry season. This is due to the high concentration of spores in the lower sediments of pans. As the pans dry the bacteria becomes more concentrated. Vultures are thought to be one of the major transmitters of anthrax into pans. However when one thinks that the spores can survive in the environment in a dormant state for seventy years, it is a moot point to try and determine which animals are responsible for introducing the the disease as the disease is in the environment and all the animals are really doing is stirring the bacteria around.

Sharp-toothed Catfish (Clarias gariepinus) trying to get under a rock and into the mud. These fish will lay dormant during dry spells in the mud of pans. When it rains again they will emerge and continue their life in the pan.

In closing, I wanted to add that I had a really different image in my mind of the mighty Limpopo River. The first day we walked to the banks of the river there was not even a trickle of water. The river has been strangled by human activity up course and many of its tributaries are dammed up. In January 2013 the Limpopo revealed it’s true nature when the river flooded and caused mass destruction as the water rose and pushed its way towards the Indian Ocean. In some areas one can see debris high up in trees that show the height of the flood. The width that the river swelled up to was also incredible. One can see debris in trees more than two kilometres away from the river.

The Limpopo River. Nothing but sand. Across where the treeline begins is Zimbabwe. To see this river flowing from bank to bank must have been a memorable sight.

This is an image of the Luvhuvu River which drains into the Limpopo. The debris in the top of this tree is the high water mark from the floods in 2012. That is about 20 metres up from where the water is in this picture. To think that all that water was pumping into the Limpopo is incredible. The potential power these rivers have is more than man can harness.

Human influence on the river in times of flood is trivial. When this river flows nothing can stop it. I like to think of a time in the future when the area experiences another wet cycle and the river can resume its mighty nature. Nature is robust and even though humans believe our short time here is significant, it is not. This river will rise again and we can be certain of that.