The Great Rift Valley (Swahili: Bonde la ufa) is a series of contiguous geographic trenches, approximately 7,000 kilometres (4,300mi) in total length, that runs from Lebanon in Asia to Mozambique in Southeast Africa.[1] While the name continues in some usages, it is rarely used in geology as it is considered an imprecise merging of separate though related rift and fault systems.
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This valley extends northward for 5,950 km through the eastern part of Africa, through the Red Sea, and into Western Asia. Several deep, elongated lakes, called ribbon lakes, exist on the floor of this rift valley: Lake Malawi and Lake Tanganyika are examples of such lakes. The region has a unique ecosystem and contains a number of Africa's wildlife parks.
Today these rifts and faults are seen as distinct, although connected, but originally, the Great Rift Valley was thought to be a single feature that extended from Lebanon in the north to Mozambique in the south, where it constitutes one of two distinct physiographic provinces of the East African mountains. It included what today is called the Lebanese section of the Dead Sea Transform, the Jordan Rift Valley, Red Sea Rift and the East African Rift.[2] These rifts and faults were formed 35 million years ago.
The East African Rift follows the Red Sea to the end before turning inland into the Ethiopian highlands, dividing the country into two large and adjacent but separate mountainous regions. In Kenya, Uganda, and the fringes of South Sudan, the Great Rift runs along two separate branches that are joined to each other only at their southern end, in Southern Tanzania along its border with Zambia. The two branches are called the Western Rift Valley and the Eastern Rift Valley.
In Kenya, the valley is deepest to the north of Nairobi. As the lakes in the Eastern Rift have no outlet to the sea and tend to be shallow, they have a high mineral content as the evaporation of water leaves the salts behind. For example, Lake Magadi has high concentrations of soda (sodium carbonate) and Lake Elmenteita, Lake Bogoria, and Lake Nakuru are all strongly alkaline, while the freshwater springs supplying Lake Naivasha are essential to support its current biological variety.
The southern section of the Rift Valley includes Lake Malawi, the third-deepest freshwater body in the world, which reaches 706 metres (2,316ft) in depth and separates the Nyassa plateau of Northern Mozambique from Malawi. The rift extends southwards from Lake Malawi as the valley of the Shire River, which flows from the lake into the Zambezi River. The rift continues south of the Zambezi as the Urema Valley of central Mozambique. Some people would wonder how long will the rift remain stable.[4]
Steinbruch, Franziska (2010). Geology and geomorphology of the Urema Graben with emphasis on the evolution of Lake Urema, Journal of African Earth Sciences, Volume 58, Issue 2, 2010, Pages 272-284. ISSN 1464-343X, https://doi.org/10.1016/j.jafrearsci.2010.03.007.
East African Rift Valley lakes, 2006, OCLC76876862
Photographic atlas of the Mid-Atlantic Ridge Rift Valley, 1977, ISBN978-0-387-90247-0
Rift Valley fever: an emerging human and animal problem, 1982, ISBN978-92-4-170063-4
Rift valley: definition and geologic significance, Giacomo Corti (National Research Council of Italy, Institute of Geosciences and Earth Resources) – The Ethiopian Rift Valley, 2013,