In this video, Oliver Coulson from Safari Consultants explains the geological formation of Botswana’s famous Okavango Delta, one of Africa’s finest wildlife regions.
Transcript
The Okavango Delta is probably Botswana’s most famous wildlife region. Looking back into Botswana’s geological past allows us to explain how the unique habitat of the Okavango Delta was formed. In this video we will give you a brief outline of the historic tectonic activity that has led to incredible changes in the country’s landscape, giving us the beautiful scenery we see today.
As you may remember from your geography lessons at school, the continents of earth were once joined in one huge ‘super-continent’ called Gondwanaland. About 100 million years ago Gondwanaland began to break up, and as tectonic plates shifted, the continents moved away from each other.
Fast forwarding to about 65 million years ago, the area of Africa that is now modern day Botswana was probably very arid. The region’s rocks were gradually eroded by wind and weathering, creating lots of sand. This sand eventually accumulated to form the vast Kalahari desert.
Rivers:
About four or five million years ago, almost yesterday in geological terms, three of the major rivers of the region; the Okavango, Kwando and Zambezi rivers all flowed along completely different courses than they do today. In the past, these rivers almost certainly flowed southwards into a large inland depression in the heart of the Kalahari. This large inland sea had one outlet, into either the Orange or Limpopo rivers.
Fault lines:
However, Northern Botswana has a series of fault lines running deep beneath the ground. The fault lines under Botswana are part of the same parallel faults that are pulling away from each other, forming the Great Rift Valley further north in Africa.
Over the next few millennia, seismic shifts cause central and southern Botswana to rise. As you can see from the following slides, this tectonic activity had a dramatic influence on the rivers.
The Kwando and Zambezi rivers were forced by a series of faults to flow eastwards. You can see the dramatic effect the Linyanti fault had on the Kwando as it dog-legs sharply to the north-east.
With the vast inland sea now starved of its water source, it started to dry and has ended up today as the area known as the Makgadikgadi Pans.
The Okavango River was affected by two prominent fault lines, the Gumare to the north and the Thalamakani to the south. This further restricted the water flow into the Makgadigadi which eventually dried up completely and now only holds seasonal rainfall.
Some geologists say that the land between the faults may have sunk by as much as 300 metres, but there is little visible evidence of this today. What is visible, is that this ‘captured’ water resulted in the spectacular creation that is the Okavango Delta.
The Okavango today:
The Okavango is the largest inland delta in the world and covers an area of some 15,000 square kilometres. The Okavango is a wildlife paradise, and a haven for an incredible array of flora and fauna. The ecosystem is home to many species, including sitatunga, the shy swamp-dwelling antelope which has adapted ‘splayed hooves’ for easy movement on the reedbeds.
Hippos, elephants, antelopes, crocodiles, rhinos, lions, leopards, cheetahs, hyaenas and wild dogs can also all be seen.
Especially interesting bird species include: the Pel’s fishing owl, African finfoot, African skimmer, and in my opinion, Botswana’s best named bird; the psychedelically coloured: purple gallinule.