Geology of Africa

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Motion of Nubia Plate Motion of Nubia Plate.gif
Motion of Nubia Plate
Central African Shear Zone Central African Shear Zone.svg
Central African Shear Zone

The geology of Africa is varied and complex, and gives rise to the wide variety of landscapes found across the continent.

Contents

The African continent rests over two main plates. The African plate, accounting for the whole of north Africa, and the Somali plate, which accounts for the eastern side of mid and southern Africa. [1] The Somali plate is moving away from the African plate in a split from Djibouti in the north, to Eswatini in the south. [2] The parting of these two plates formed the southern part of what used to be known as The Great Rift Valley. [3] In geological terms, the African and Somali plate separation has formed the East African Rift System (EARS), comprising two separate rifts systems - the Eastern Rift Valley, [4] and a western branch known as the Albertine Rift. [5]

Two massive domes were formed, the Kenyan dome and the Ethiopian dome (known as the Ethiopian Highlands). The Albertine Rift follows the western edge of the Kenyan dome. This runs from Lake Malawi in the south, up into Lake Rukwa, Lake Tanganyika and Lake Albert in the north, where it ends. The Kenyan dome has the eastern branch of the EARS (known as The Gregory Rift) running through its middle, and contains most of what we historically saw as the Great Rift valley. Lake Victoria lies in the middle of the dome, with the Gregory Rift to the east of it. The Gregory rift has Lake Eyasi & Lake Manyara at its southern end, running north up to the west of Nairobi and continuing on through Kenya to Lake Turkana - which lies between the northern edge of the Kenyan dome and the southern edge of the Ethiopian dome. [6] The Ethiopian dome is split down the middle by the Eastern Rift, formed by the developing plate boundary, and has formed a valley running from Lake Chamo and Lake Abaya in the south, widening through Lake Shala, Lake Ziwa and Lake Koku, until it reaches its widest point some 110 kilometres (68 mi) from Djibouti.

1930s geological map of Africa Map Geological Map of Africa 1928-1940 - Touring Club Italiano CART-TRC-24.jpg
1930s geological map of Africa

Major geological events

Geological features

Geologists of Africa

Geological maps

See also

Related Research Articles

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<span class="mw-page-title-main">East Africa</span> Eastern region of the African continent

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<span class="mw-page-title-main">Rift Valley lakes</span> Group of lakes in the East African Rift

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<span class="mw-page-title-main">East African Rift</span> Active continental rift zone in East Africa

The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. It was formerly considered to be part of a larger Great Rift Valley that extended north to Asia Minor.

<span class="mw-page-title-main">Afar Triangle</span> Geological depression caused by the Afar Triple Junction

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<span class="mw-page-title-main">Albertine Rift</span> Western branch of the East African Rift

The Albertine Rift is the western branch of the East African Rift, covering parts of Uganda, the Democratic Republic of the Congo (DRC), Rwanda, Burundi and Tanzania. It extends from the northern end of Lake Albert to the southern end of Lake Tanganyika. The geographical term includes the valley and the surrounding mountains.

<span class="mw-page-title-main">Afar Triple Junction</span> Place where three tectonic rifts meet in East Africa

The Afar Triple Junction is located along a divergent plate boundary dividing the Nubian, Somali, and Arabian plates. This area is considered a present-day example of continental rifting leading to seafloor spreading and producing an oceanic basin. Here, the Red Sea Rift meets the Aden Ridge and the East African Rift. The latter extends a total of 6,500 kilometers (4,000 mi) from the Afar Triangle to Mozambique.

<span class="mw-page-title-main">Great Rift Valley, Ethiopia</span> Branch of the East African Rift that runs through Ethiopia

The Great Rift Valley of Ethiopia, is a branch of the East African Rift that runs through Ethiopia in a southwest direction from the Afar Triple Junction. In the past, it was seen as part of a "Great Rift Valley" that ran from Mozambique to Syria.

<span class="mw-page-title-main">Great Rift Valley, Kenya</span> Part of an intra-continental ridge system that runs through Kenya

The Great Rift Valley is part of an intra-continental ridge system that runs through Kenya from north to south. It is part of the Gregory Rift, the eastern branch of the East African Rift, which starts in Tanzania to the south and continues northward into Ethiopia. It was formed on the "Kenyan Dome" a geographical upwelling created by the interactions of three major tectonics: the Arabian, Nubian, and Somalian plates. In the past, it was seen as part of a "Great Rift Valley" that ran from Madagascar to Syria. Most of the valley falls within the former Rift Valley Province.

<span class="mw-page-title-main">Gregory Rift</span>

The Gregory Rift is the eastern branch of the East African Rift fracture system. The rift is being caused by the separation of the Somali plate from the Nubian plate, driven by a thermal plume. Although the term is sometimes used in the narrow sense of the Kenyan Rift, the larger definition of the Gregory Rift is the set of faults and grabens extending southward from the Gulf of Aden through Ethiopia and Kenya into Northern Tanzania, passing over the local uplifts of the Ethiopian and Kenyan domes. Ancient fossils of early hominins, the ancestors of humans, have been found in the southern part of the Gregory Rift.

<span class="mw-page-title-main">Turkana Basin</span> Large endorheic basin mainly in Kenya and Ethiopia

The greater Turkana Basin in East Africa determines a large endorheic basin, a drainage basin with no outflow centered around the north-southwards directed Gregory Rift system in Kenya and southern Ethiopia. The deepest point of the basin is the endorheic Lake Turkana, a brackish soda lake with a very high ecological productivity in the Gregory Rift.

<span class="mw-page-title-main">Aswa Dislocation</span>

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The geology of Uganda extends back to the Archean and Proterozoic eons of the Precambrian, and much of the country is underlain by gneiss, argillite and other metamorphic rocks that are sometimes over 2.5 billion years old. Sedimentary rocks and new igneous and metamorphic units formed throughout the Proterozoic and the region was partially affected by the Pan-African orogeny and Snowball Earth events. Through the Mesozoic and Cenozoic, ancient basement rock has weathered into water-bearing saprolite and the region has experienced periods of volcanism and rift valley formation. The East Africa Rift gives rise to thick, more geologically recent sediment sequences and the country's numerous lakes. Uganda has extensive natural resources, particularly gold.

References

  1. Schlüter, Thomas (2006). Geological Atlas of Africa (1st ed.). Springer-Verlag. pp. 26–29. ISBN   978-3-540-29144-2.
  2. "Somali Plate". Ashten Sawitsky. Retrieved 30 June 2015.
  3. Fernandes, R.M.S.; Ambrosius, B.A.C.; Noomen, R.; Bastos, L.; Combrinck, L.; Miranda, J.M.; Spakman, W. (2004). "Angular velocities of Nubia and Somalia from continuous GPS data: implications on present-day relative kinematics". Earth and Planetary Science Letters . 222 (1): 197–208. Bibcode:2004E&PSL.222..197F. doi:10.1016/j.epsl.2004.02.008.
  4. Dawson 2008, p. 2.
  5. Owiunji & Plumptre 2011, p. 164.
  6. Schlüter, Thomas (2006). Geological Atlas of Africa (1st ed.). Springer-Verlag. p. 228. ISBN   978-3-540-29144-2.

Works cited

Further reading