NAMIBIAS GEOLOGY TREASURES

Part of the Etosha National Park, which in 2007 celebrated its 100th anniversary, the Etosha Pan covers an impressive 4760 km , with a maximum N-S extent of 80 km and an E-W extent of 120 km. Although the Etosha Park is most famous for its diverse wildlife, which includes almost the entire spectrum of African big game, the pan itself, with its eerie atmosphere of desolation, attracts a great number of visitors, too. Most of the time a dry, almost completely flat, salt pan of glistening white, after strong rains it still reminds of its former glory, when the area was covered by a lake that, if it existed today, would be the third largest in the world.


Lying at an altitude of some 1100 m above sea level Etosha Pan is surrounded by extensive grass and thornbush savannahs, with an average annual rainfall of 300 mm. Some 22000 km2 (including the pan) of this northern Namibian plain were set aside as a National Park in 1907, making Etosha the sixth largest National Park in the world.


The Etosha Pan forms the lowest point of the Owambo Basin, a large intracontinental sedimentary basin, floored by mesoproterozoic rocks of the Congo Craton, and containing some 8000 m of sedimentary rocks. The immediate bedrock of the pan consists of silts and sands of the Andoni Formation and Etosha limestone, which belong to the Cenozoic Kalahari Group. Only the very uppermost part of the lithological profile of Etosha Pan is subject to alteration by recent flood waters, and exhibits a mineral assemblage char- acteristic of a saline-alkaline environments (e.g. East African salt lakes), including analcime, K-feldspar, sepiolite, saponite, calcite, dolomite, strontianite and various salts. Although shades of off-white are the predominant “colours”, large parts of the pan surface display a distinct green-gray hue, which is caused by the micaceous mineral glauconite.


Geological History


The development of Etosha Pan involves the formation of a palaeo-lake, followed by erosion. The palaeo-lake was formed through a drainage system including the upper Kunene and Okavango Rivers in the Late Miocene, some 5 to 7 million years ago. At the time of its maximum extent (ca. 3 Sketch of the rise and fall of “Lake Etosha” Mudcracks characterize the fine-grained pan sediment rainfall and flood events. Erosion set in, with fluvio-lacustrine processes in the rainy season and aeolian deflation processes during the dry season, which formed the prominent dunes to the north- west of the pan.


Game and Water - Etosha’s assets


A number of springs occur along the south- ern margin of Etosha Pan, which provide water for the 114 mammal species, 340 bird species, 110 reptile species, 16 amphibian species and, surprisingly, one species of fish, found in the Park. During the long dry season, when other resources have dried up, it is upon these permanent waterholes the game congregates, thus making them favourable viewpoints for an Landscape of contrasts for an impressive parade, especially during the hours of dawn and dusk. The source of the life- sustaining water are the Neoproterozoic dolomites of the Otavi Mountainland to the south of the Etosha pan. Karst structures in these mountains (e.g. Otjikoto Lake) provide ample mobility for groundwater, and where the carbonate rocks are in contact with the clay- rich and impermeable sediments of the younger Kalahari Group, it comes to the surface to form springs. 


Source: Roadside Gelology of Namibia and others. 


See Etosha Brochure Facts & Figures | See Important Bird Area - Etosha National Park


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