Makgadikgadi Sea .

Makgadikgadi Sea .
Andre Willers .

Update : 26 Oct 2010
Also Magadigadi sea , Makgadigadi sea , Magadikgadi sea .
Also shown in "DaMing Hun Yi Tu" ("Amalgamated map of the Great Ming Empire") dated 1398 AD on 17 square meters of silk , thought to be based on data about 1320-1380 AD , from preparation explorers before the Admiral He fleet .

See http://news.bbc.co.uk/2/hi/africa/2446907.stm

This includes a map clearly showing the inland sea before it drained through Kariba , and Orange River as described below .

Accuracy :
The latitudes could then be measured fairly accurately , but the longitudes seem slightly wonky . However , what is interesting is what is not shown : ie the outlets of the Zambezi or the Orange , though it does show the outlet of the Cunene at the correct latitude . Major mountain ranges are also shown at correct latitudes .

We suspect that at the time of the mapping (circa 1320 AD) , the outlets of the Zambezi and Orange rivers did not exist , but were opened shortly afterwards by tectonic action of the active faults in the regions .

What the map does show is the Caledon , ending in an endorheic basin roughly bounded today by Coleberg-Tarkastad-BarkleyEast.

The tributary/outflow shown to the south of the Makgadigadi Sea is more interesting . The flow here would be towards an endorheic basin roughly bounded by Prieska-VictoriaWest-Sutherland . The map shows the Makgadigadi Sea to be rather full at the time , so the water flow would have been into this endorheic basin .
In times of drought , the Makgadigadi Sea would shrink and the flow would reverse .

An alternate endorheic basin is roughly Upington-Garies-Calvinia . This would be accessable depending on tectonic activity . (It is a bit lower than the previous basin)

Tectonic activity would also periodically open the Orange and Zambezi outlets to the oceans .

Fluctuate this over geologic time , and you have diamond deposits from the weathering of the volcanoes formed after the Vredefoort impact .
These have been found at the Orange outlet , Upington-Garies-Calvinia basin (eg Hexriver diamonds) , Botswana , Zimbabwe .

But , nobody has really looked at the Prieska-VictoriaWest-Sutherland endorheic basin . There should be very rich alluvial diamond pockets in potholes in the old riverbeds as the water swished back and forth .


Gas and Oil :
Endorheic basins are usually associated with gas or oil if they fluctuated over geologic timespans . Biologic material gets washed into basins with no outlet , covered up and pressurized . Voila! At least gas . Maybe oil .

You know you have struck it rich when
Your borehole at Sutherland blows and the diamonds clog the oil-filters .

Have fun!

Andre

-------------------------
Previous article:
Makgadikgadi Sea .

28 Aug 2009

Synopsis :
Southern Africa had a large interior freshwater sea until historical times , with major effects on human evolution and regional climates .

Discussion :
Map source : Reader's digest "Atlas of the World" (1993) ISBN 0-276-42001-264-7 .
P128 : Map of Southern Africa .
See http://news.bbc.co.uk/2/hi/africa/2446907.stm
Wikipedia , Google . See appendices .

The topographical map clearly shows a major basin with 200 – 1000 meter elevation

Location :
Bounded by 16 to 28 degrees latitude (longest about 1 320 km) ,
The width varies : roughly hourglass-shape . At the narrowest in the middle : 23 to 25 degrees longitude (about 240 km) at about latitude 22 degrees .
The widest about 500 km . Bounded in the east by about 27 degrees longitude , and the west by 20 degrees longitude .

The basin is bounded by higher elevations and mountains on all sides , except for the breakthrough gap of the Zambezi at Victoria Falls .

Faults :
Roughly the line from Worcester – Grootvlei – Kakamas – Khakea – Lake Ngami – Victoria Falls – Present course of Zambezi to Great Rift Valley .

Essentially a branch of the Great East African Rift . See the Luangwa river plains .
See also Zimbabwe – Kalahari Axis , Gumare fault .See Appendices .

Note that these faults runs right through the center of the old Kalahari Sea , and was thus sensitive to the changes in it's water level . This in turn was sensitive to rainfall and river-inflow / outflow balance . Changes in the weight of the water would cause changes in seismic activity .

The faults are quite active (cf Tulbagh earthquakes , when the southernmost end had a mild 6.8 tremor.) . The Zimbabwe – Kalahari Axis and Gumare fault have been active in historical times , but with long intervals . Overdue . .

Periodic fluctuations .
The entire system is seismically sensitive to climate fluctuations caused by the periodic filling and emptying of the Makgadikgadi Sea . Hence the zig-zag pattern of the Victoria Falls gorges .

Climate .
There is also a complex feedback with rainfall patterns in the catchment areas of the feeder rivers . The system is an endorheic basin (internal drainage-see Appendix B)
But such a large body of water and concomitant vegetation drastically alters the rainfall in its region .
See http://andreswhy.blogspot.com "Biotic pump"
Notice the orientation of rivers on the sides of the old sea (ie Namibia , Angola) . They are all on the side of ridges facing the basin , ie from where moisture will come . A large percentage of moisture simply recirculated within the basin .

During the full episodes , it simply overflowed through the Limpopo .
Earthquakes opened the Victoria Falls portal . The water level fell . Moisture recirculation fell . The borders dried up . If this coincides with a dry climate period , we get the present shrinkage to marshes at the deepest parts .
Earthquakes sooner or later close the Victoria Falls portal , and the process reverses .
This has been going on for more than 3 million years (see Appendix C) .
The latest reversal started about 10 000 years ago , with the major climate shift at the end of the ice age .

Orange River .
Note the very peculiar fact that most major rivers in South Africa (Orange , Vaal , Harts , Modder , etc) are on top of ridges . This has led to some interesting squirming by geologists , since water has this well-known propensity to flow downhill . The explanations are suitably convoluted and involve escarpments , really long stretches of time and lots of erosion .
Whatever , it still means that the major rivers are unstable vis-a-vis major tectonic movements , but may be self-sealing due to heavy silting .Though this takes some heavy swallowing .
But the Orange river has a high probability of also periodically emptying into the Inland Sea . Most probably about 60 km downstream from Kakamas , where it comes nearest to the Molopo .
This is not an idle question , since such an old riverbed will be lousy with alluvial diamonds . Might even be gold-nuggets from the Vaal .

Human Evolution .
See Appendix D .
The point actually pinpointed is where the borders of present RSA , Namibia and Botswana meet . This is not an accident , since the borders follow habitability . This is where the Nossob river meets the westernmost part of the old inland sea . An ideal place for human evolution .
Lots of food , easily gathered . A whole sea of potable water .Lots of caves . An extended coastline to accommodate expanding population or climatic change . An outlet to the South-South-West with no unsurmountable barriers for the bored and rebellious .

The inhabitants of Pinnacle Point near Mosselbay were thus colonizers , migrating via the West Coast . They were stopped by the dense Tsitsikama forest and inhospitable terrain past that . The really inhospitable central plateaux were only the populated by outcasts , criminals and refugees .

Others on the inland sea would move northwards during fluctuations , eventually ending up in the Rift Valley system . From there they could easily move northwards , using well-known strategies and technologies next to the rift lakes . Bypassing the whole problem of latitude crossing (cf Jared Diamond) .

Back-pressure .
The periodic nature of the process means that after the first migration , and after Toba
(73 000 BP) , there would be people already there . But population density was low and newcomers (essentially refugees) , were helped on their way , eventually towards North Africa , Middle-East , Asia and Europe . This attitude (called Ubuntu) is still a characteristic of most ordinary people in Africa .

Interesting asides :
Aquatic human episode : a freshwater sea like the Magadikgadi Sea would be a much more benign environment for such evolutionary development than salt-water ocean . Note the trainable capability of humans to see underwater (not very well known , but well documented) .

More telling is Click . See http://andreswhy.blogspot.com "Click and human Evolution" Click sounds aid fishing . Do humans still use this ? (without technology)
The inland sea teemed with fish . Clicking would not only locate , but also chase fish into weirs or nets . We know they used weirs (stone weirs have been found by archeologists in areas like Mosselbay) . The efficiency of clicks (mimicking predators like dolphins) would be very efficient in chasing fish . They would also attract dolphins , which would share of the largesse . The beginning of a long cupboard love .

With the invention of agriculture , click-languages fell out of fashion .
"So last year .Who needs the effort ." But some aquaculture enclaves might still have it . Cf surprising Chinese efficiency in freshwater aquaculture . Do they cluck ?
Was the first domestication done simply by seeing which animals responded to clicks , then selecting and breeding . This could be easily tested .

Chickens and falcons also respond better to clicks . How deep does it go ? I will need a lot of convincing for a virus click-whisperer . What about a homeopathic click-whisperer ? The shaman has click-whispered into this large body of water and it is transmitted . Sigh . Many humans believe exactly that . Holy water .


Endorheic Pumps.
See Appendix B

Basins which have internal drainage act like pumps to any living organisms inside them . Because of the interaction between rainfall and vegetation , there is a feedback oscillation . When times are good , populations increase . When times are bad , the tough emigrate , and export their troubles .

The Magadikgadi basin is probably the oldest , but the Tibetan Plateau is not far behind . Ditto the steppes of Mongolia , Aral and Black Seas . North Africa (Lake Fezzan , Lake Chad) , the whole Arabian and Sinai peninsulas , northern Mexico , Middle-West USA are examples . All the troublespots . Even small climatic fluctuations cause trouble if the population is over carrying capacity .


Zimbabwe I
See http://andreswhy.blogspot.com "Fractal collapse of societies"
For about 2000 years , to about 1400 AD , there was a flourishing civilization around the borders of the inland sea . The climate in the highland-areas around it was very benign , with rain the year around . Extensive ruins of terraced agriculture are discernable . The center was in Zimbabwe .
Value added items were exported to India , Arabia mainly gold , minerals and precious stones Like now .
See the photo's in Adam's Calender by Heine and Tellinger . (ISBN 1-920153-07-1) .
Especially p25-p27 . Kilometers of ruins showing clear evidence of agriculture (terraced ,nogal) and husbandry , with market mechanisms (roads , but no evidence of wheel tracks) . Though the authors try hard , the ruins are patently fresh . They show less weathering than equivalent Roman ruins in Europe . They are younger than 1000 years . There is no evidence of Deep Time . Stone fences are still above ground . Terraces are evident . Not very old at all . But still indicative of a flourishing society about 100 BC to 1400 AD .

So what happened ?
A severe earthquake opened up Victoria Falls again and the inland sea started draining . This coincided with the latest long-term drying-up . A tipping point was reached (because of the feedback effect) , and things went to hell in a handbasket quickly after that . There was already shrinkage before that , but this was the coup-de-grace .

The overseas merchants (Dravidian South Indian merchant class – the Komati) cut their losses and departed . Markets shrunk . The locals abandoned expensive agriculture , especially as the climate changed . The shrinkage was gradual . When the final pull-out occurred , the remnants could live on the land in a simple subsistence economy .
What remained was kilometers of ruins (like Rome before the Renaissance.)

Note that this was not a failure of civilization , but an effect of climate change .
The market disappeared because the infrastructure to feed the labour force was no longer sufficient . A market cannot create a climate . (Not then , in case)

What can we do about it ?
Well , we can rob the Congo river or the Rift lakes , but that is inelegant .
(Ne kulturny)
An elegant solution is to punch a channel underground to below 1000 meters in the Atlantic , use the pressure to squirt the water into basin , after desalinating it .

The technology exists :
1.The tunnel :
Sub-Crustal torpedoes . Submarine versions are already in use with the Russian and USA navies . Simply a high-speed projectile that uses vaporized plasma ahead of it to change the phase of the material . A train of them condenses the plasma on the sidewalls as a strong material .Cheap .

2.The desalination :
See http://andreswhy.blogspot.com "Negative Pressure : an important update" 6 Mar 2009 .
The nanotechnology is due at any moment . By it's very nature , it is high throughput .

3. The ideal spot :
The top reaches of the Nossob river , about midway between Okanhanja and Epokira . From there is an uncomplicated run for a sub-crustal missile to the Atlantic towards the south-west .. The further advantage is that the flooding would be via a natural river . It would be truly spectacular . It is doubtful that they could get the right depth on first try , but would rather go too deep , than too shallow . A huge permanent geyser of water hundreds of meters high would result . An inverse waterfall , to rival Victoria Falls .

4. What if the desalination is not ready ?
(Yakkity-yak humans –most likely)
A sea-water sea would be nearly as acceptable . The climatic effects would be similar. We have a model in the Black Sea .
Do the same in other endorheic basins ? Libya might do it first . Or repopulating the Aral sea . The Black Sea can do with some topping up .
This can be done definitely within 6 months from now .
See map of endorheic basins in Arabia and Sinai .
Not to mention India . Or Australia . They really need it .

5. Ocean current climatology will suddenly assume a new strategic importance .

6. The defense strategic importance of sub-crustal missile technology .
Nil .
They cannot defend against super-crustal missiles . So that is not applicable . The thing a nation or civilization has to worry about is resources . And this technology frees up the oceans' resources .
Ecology is the major worry , and avenues for that exist .

7. Money .
There is an incredible amount of money to be made .
Actually made . Real wealth creation . Millions of acres made fertile even with just saline water nearby . The carbon credits of a sub-ocean fountain dissolving CO2 alone will pay the fairly modest capital costs (about $500 million) . Sneer at iceberg-towing.
Global flooding ?. Rather worry whether there is enough water in the oceans to satisfy human demand .
An interesting exercise : calculate the remaining sea-level after maximal usage of sea-water . (Hint : look at ice-ages . Would we use the water-equivalent of miles thick glaciers on land ? Easily .Crops , drinking , industrial etc . But remember , if it is properly cleansed , it is borrowed . It does get returned to the ocean . But an awful lot of it is "in use" , in the air as it were . This percentage will increase .)

Industrial demand will lead to such a shortage of water that it would be economical to import water from the Saturn orbital clouds .

8. Parallel sub-crustal missiles .
I am deeply unhappy about the fact that major river systems in South Africa are on hard ridges . It is simply unstable , unless there is a deep trench in the river bed . The only way I can think of is a a collapsed tunnel . Drilled by a sub-crustal missile .
Meteor impact :
If you look at the paths of the Vaal ,Caledon and Orange rivers and backtrack , you see that the tracks meet at 36.67 degrees longtitude and 26.78 latitude . This would be the putative impact point of a meteorite that split into two and tunneled under the crust for about 1 620 km till the two plasma bodies slowed to a threshold velocity and they swerved sharply towards each other . They impacted roughly where Hopetown is now . (A bit to the south-east , actually .) Expect diamonds .

What to expect at the impact point :
This is about 200 km from Beira . This has been a carbon rich area for a long time . I do not know when the impact took place , but even if it was a fragment of the Vredefoort meteor there would still be gas and maybe oil deposits formed by the impact waves .

Note the lightning-like offshoots before the final .

At the end , quantum distribution of charge on the plasma body overwhelms internal coherence and the two bodies rush towards each other and self-annihilate .
Violent energy release results .

Hence the little stretch of the Orange river between Colesberg and Kimberley .

What to expect at the impact point (36.67 degrees longtitude and 26.78 latitude) .
This is in the Mozambique channel . There should be oil and gas in a radius of 120 km .
The two missile trajectories passed on either side of Nelspruit , with dense rock concentrators on either side . There should be at least gas , probably oil .
Something similar at Bloemfontein , but probably only gas .(Figures)
Notice all the thermal springs around .

At Nelspruit : narrow at the top and wide at the bottom . Quite large .

Andre .

xxxxxxxxxxxxxxxxxxxxxxxxxxxx

Appendix A
Geological changes to the course
More than two million years ago, the Upper Zambezi river used to flow south through what is now the Makgadikgadi Pan to the Limpopo River. The land around the pan experienced tectonic uplift (perhaps as part of the African superswell) and a large lake formed, and extended east.
Meanwhile, 1,000 kilometres (620 mi) east, a western tributary of the Shire River in the Great Rift Valley's southern extension through Malawi eroded a deep valley on its western escarpment. At the rate of a few cm per year, this river, the Middle Zambezi, started cutting back the bed of its river towards the west, aided by grabens (rift valleys) forming along its course in an east-west axis. As it did so it captured a number of south-flowing rivers such as the Luangwa and Kafue.
Eventually the large lake trapped at Makgadikgadi (or a tributary of it) was captured by the Middle Zambezi cutting back towards it, and emptied eastwards. The Upper Zambezi was captured as well. The Middle Zambezi was about 300 metres (980 ft) lower than the Upper Zambezi, and a high waterfall formed at the edge of the basalt plateau across which the upper river flows. This was the first Victoria Falls, somewhere down the Batoka Gorge near where Lake Kariba is now.[6] For details of how the falls cuts back its bed to form the gorge, see How the Victoria Falls formed.
The Zambezi region was known to medieval geographers as the Empire of Monomotapa, and the course of the river, as well as the position of Lakes Ngami and Nyasa, were given broadly accurately in early maps. These were probably constructed from Arab information.
Appendix B
List of endorheic basins
From Wikipedia, the free encyclopedia
The following is a list of endorheic basins — watersheds which do not drain to the sea.
Appendix C
Lake Makgadikgadi
From Wikipedia, the free encyclopedia
Lake Makgadikgadi is an ancient lake that existed in what is now the Kalahari Desert in Botswana. It may have once covered as much as 80,000 km² and been 30 m deep. The Okavango, Zambezi, and Cuando rivers once all emptied into the lake.
Origin and History
Approximately 3 million years ago, strong easterly winds brought about the formation of elongated dunes which ran from east to west across the middle of the Kalahari Desert. During wetter times, these dunes channeled the flow of the great rivers of the area, the Okavango, Chobe, and Zambezi, eastwards with the Limpopo River into the Indian Ocean.
About 2 million years ago, the formation of the fault known as the Kalahari-Zimbabwe axis, which runs from the Zimbabwe capital Harare through its second-largest city Bulawayo and ends in the eastern side of the Kalahari, created an enormous basin and forced these rivers to flow into and fill up the basin. Lake Makgadikgadi was thus created.
As the millennia passed, the lake was filled to capacity and began to overflow. About 20,000 years ago, as a result, it began to drain northwards and then eastwards. This caused the middle and lower Zambezi Rivers to connect, resulting in the formation of Victoria Falls. With the water now able to flow out of the basin, Lake Makgadikgadi was able to drain partially and its average level decreased.
A drier climatic period followed which caused an increase in evaporation and a decrease in the flow of the rivers that fed it. By about 10,000 years ago the drying of Lake Makgadikgadi was in an advanced stage. Sediment and debris from the Okavango River and windblown sand were gradually filling the lake.
The formation of the Gumare fault caused a reduction in the elevation of the land. As a result, the water of the Okavango River spread out over a much larger area of land than it previously did, forming the now characteristic fan-shaped inland delta of the Okavango, which further reduced the water that flowed into Lake Makgadikgadi and hastened its demise.
Today the only remains of Lake Makgadikgadi, are the Okavango Delta, the Nxai Pan, Lake Ngami, Lake Xau, the Mababe Depression, and the two main Makgadikgadi pans of Sua and Nwetwe.
Ecology
Lake Makgadikgadi is theorized to have been the birthplace of the vast number of cichlids[1] that once swam the Congo River, Zambezi River, Okavango River and Limpopo River - as many as 100 to 400 new species, of which approximately 25 survive today. The lake's sheer size may have provided the ancestors of these fish with an extremely wide range of new ecological niches to exploit and thus could have served as the stimulus for the evolution of the new species, which they may have done in record time before the lake drained completely. The theory further says that the newly evolved species, after having evolved within the confines of the lake, could have escaped with the waters of the lake as it drained, and populated the rivers of the region to evolve into the cichlids that exist today.
In current times this land is desiccated most of the year and is a seasonal wetland in the rainy summer months.[2]
References
· C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham [1]
· James Owen (May 4. 2005) Lost African Lake Spawned Fish Diversity "Beyond Belief. National Geographic News[2]
Coordinates: 20°43′0″S 24°57′3″E20.71667°S 24.95083°E
Retrieved from "http://en.wikipedia.org/wiki/Lake_Makgadikgadi"
Categories: Former lakes | Geography of Botswana | Makgadikgadi Pan | Pleistocene

Appendix D

Human Evolution .
Snip from a NYT article about a new study by a group of geneticists which pins the origin of humankind to a spot on the coast of southwest Africa near the Kalahari Desert. The study is said to be the largest ever of its kind on African genetic diversity. The researchers say Africans are descended from 14 ancestral populations that typically correlate with language and cultural groups.
Locations for the Garden of Eden have been offered many times before, but seldom in the somewhat inhospitable borderland where Angola and Namibia meet.
A new genetic survey of people in Africa, the largest of its kind, suggests, however, that the region in southwest Africa seems, on the present evidence, to be the origin of modern humans. The authors have also identified some 14 ancestral populations.
The new data goes far toward equalizing the genetic picture of the world, given that most genetic information has come from European and Asian populations. But because it comes from Africa, the continent on which the human lineage evolved, it also sheds light on the origins of human life.
The research team was led by Sarah A. Tishkoff of the University of Pennsylvania, and reported in in a recent issue of Science: "The Genetic Structure and History of Africans and African Americans." (via Ned Sublette)

Appendix E
Okavango .


Greatest Places Physical Geography: Dr. Cecil Keen, July 1997 Okavango
Geographic Description: Described as "the river which never finds the sea", the Okavango in northwestern Botswana disappears into a 6,000-square-mile maze of lagoons, channels, and islands. The river system annually brings more than 2 million tons of sand and silt into the Delta, yet less than three percent of the water emerges at the other end to either flood Lake Ngami or cross another 300 miles of the Kalahari, then to enter Lake Xau and the Makgadikgadi Pans. The Okavango Delta, in the midst of the Kalhan sands, is Africa's largest and most beautiful oasis. The River Okavango, which rises in the highlands of Angola, never reaches the sea; instead its mighty waters empty over the sands of the Kalahari. Here the great Kalahari desert thirst is locally quenched in a blue-green wilderness of fresh water, with emerald reed beds and towering trees. It is a natural refuge and giant water hole for the larger animals of the Kalahari. The water gives rise to many forms of life unexpected in a "desert": There are fish, crocodiles basking on the sands, and hippopotamuses and swamp antelopes feeding on the vegetation. The Okavango is the last surviving remnant of the great Lake Makgadikgadi whose waters and associated swamps once covered much of the Middle Kalahari. It also is closely associated with the Kwando, Linyanti, and Chobe swamps and river systems to the northeast. It is thought that long ago the Okavango, Chobe, Kwando, and upper Zambezi waterways flowed as one massive river across the Middle Kalahari, to join the Limpopo River and then to the Indian Ocean. The earth movements that created the rift of the Kalahari-Zimbabwe Axis impeded this flow, causing a damming back of the giant river, which resulted in the formation of a series of high and complex swamps. As the Okavango River left the humid highlands and entered the arid flatness of the Kalahari, it slowed and dropped its sediment load. Channels became blocked and the water sought other courses, continuing to deposit its sediments wherever it traveled. Over time, some 2 million tons of sand and debris were deposited over the Kalahari sands, creating the characteristic fan shape of the Delta. The Okavango's waters still cut the characteristic fan shape of the Delta. The Okavango's waters still cut paths through this built-up cone and deposit their sand load, causing the channels to continue changing direction. Superimposed on these changes were the climate fluctuations of the last million years. In arid periods these complex swamps and waterways would recede; in wetter times the myriad channels may have combined to form one vast river flowing into a huge lake--the former Lake Makgadikgadi. 2 parallel faults now control the direction in which the Okavango River enters the Kalahari Basin, in an area called the Panhandle. Other faults also direct its exit from the Delta, flowing south into the ocean of sand. As the Okavango flows over the Gomare Fault, a continuation of the Great Rift Valley of east Africa, that runs southwest to northeast, the slope of the land breaks it up into numerous channels, which fan outwards over the Delta. These are blocked by 2 southern faults, the Kunyere and the Thalamakane, which redirect the Delta's myriad channels. The Thalamakane Fault acts as a 150-mile-long natural dam: Here the channels abruptly change direction and join to form one river, the Boteti, which flows eastwards through a break in the fault towards the Makgadikgadi Pan. A small channel, the Nghabe River, continues southwest toward Lake Ngami, serving as both inlet and outlet depending on the strength and direction of the annual floods. The present Okavango is still connected to the Chobe-Zambezi River system via the Selinda Spillway. However, recent arid conditions have meant that these water courses are now seldom joined. The geology of the Okavango is still inherently unstable, as the faults continue to move and earth tremors occur. Channels become filled with sand and debris, and massive plugs of papyrus interrupt their flow. The pattern of drainage in the Delta will continue to change. Interior drainage systems occur typically in arid areas where water evaporates to leave an accumulation of salts as a saline pan, as in Makgadikgadi and Lake Ngami. The Okavango is unique in that it forms a freshwater Delta, simply because it has several outlets. Even though their outflow comprises only three percent of the Okavango's inflow, this is enough to carry away most of the salts and keep the Delta's waters fresh. In fact there are 2 groups of outlets: west to Lake Ngami, and south and east to the Makgadikgadi Pan via the Boteti River. Although the total drainage pattern in the Delta is complex, there is an underlying simplicity in the slow and regular pulse of water that flows down each year from the Angolan highlands. South of the Panhandle the Delta fans out for many miles. During dry periods it is estimated to cover at least 6,000 square miles, but in wetter years, with a heavy annual flood, the Okavango's waters can spread over 8,500 square miles of the Kalahari's sands. Deep water occurs in only a few channels, while vast areas of reed beds are covered by only a few inches of water. The Okavango offers an oasis of habitat for prolific plant and animal life in a personified state of "balance in nature." Two plants dominate the Delta's perennial swamps: papyrus, a giant sedge (type of grass) which grows naturally only in Africa, and the willowy phoenix palm. They provide a fascinating record of recent changes in the limits of the perennial swamps. Papyrus, being a herbaceous species, responds more quickly to changes in water level than the phoenix, which is a woody species. The full extent of the perennial swamps along the Thaoge River, before it began to dry up this century, can be seen by the distribution of the phoenix palm, which extends much further south than the papyrus. Conversely, papyrus extends much farther east than the palm, along the Moanatshira system. This indicates the expansion of perennial swamps during this century. On the Boro River, the papyrus and phoenix occur in the same places, indicating that the extent of swamp areas has remained relatively unchanged in the central Delta during this century. Inhabiting the waters of the Okavango are an estimated 35 million fish of almost 80 species. The most abundant, three species of bream, are preserved from excessive predation by crocodiles feeding on the tiger fish that would prey on the bream. Hippos flatten paths through the papyrus on their nocturnal forays to graze, allowing easier access for the sitatunga and antelope to traverse across the swamps during their daytime migrations. Belts of forest fringe the swamps with tall trees giving shade to large herds of larger game. Beyond the forest fringe the landscape forms an open savanna park land, and in these drier areas the greatest concentrations of game are accompanied by the predator families: lion, leopard, cheetah, hyena, and wild dog. It is in these forest fringes and savanna grasslands that elephants and giraffes can be found browsing with antelope of almost every kind, from buffalo, wildebeest, and kudu, to sable, roan and impala. Okavango is a delicate and unique example of dynamic equilibrium at work in nature. A place worthy of being called a "greatest place."
Amazon Greenland Iguazu Madagascar Namib Okavango Tibet