A chain of linked basins running about 6,000 kilometres from Lebanon to Mozambique
The Jordan valley and the Dead Sea form its northern end; the Red Sea and Gulf of Aden branch off it
Geography · Physical geography
The Great Rift Valley
East Africa and the Levant — Mozambique to Lebanon
A chain of linked rift basins running some 6,000 kilometres from Lebanon to Mozambique, named by the Scottish geologist John Walter Gregory in the 1890s. Its African section is where the continental crust is splitting in two along the East African Rift, throwing up Kilimanjaro and the soda lakes and preserving, in its volcanic ash layers, the best early-hominin fossil record anywhere on Earth.
How to spot them
- ▸Where the African continent is tearing itself apart, and where most early hominin fossils come from
- ▸Quiz clue: 'Olduvai', 'Afar Triangle', 'Ngorongoro', 'Lake Turkana', 'Danakil'
- ▸Named in the 1890s by the Scottish geologist John Walter Gregory
- ▸Its lakes range from the second-deepest in the world to caustic soda lakes full of flamingos
Key facts
Named in the 1890s by the Scottish geologist John Walter Gregory
Its Kenyan section is still sometimes called the Gregory Rift
Its African arm is a continental rift where the crust is splitting into two plates
The Nubian and Somali plates are separating by a few millimetres a year
The Leakeys' excavations in a Tanzanian gorge on its floor transformed the study of human origins
Olduvai Gorge, where Mary Leakey found Zinjanthropus in 1959
'Lucy' was found in its Ethiopian section in 1974 (1974)
The Australopithecus afarensis skeleton from Hadar, in the Afar Triangle
Its eastern arm holds caustic soda lakes where millions of lesser flamingos feed
Lakes Natron, Nakuru and Bogoria; Natron's water can reach pH 10 and 60 °C
Its western arm holds Africa's deepest lake and the world's second deepest
Lake Tanganyika, 1,470 m deep, in the Albertine Rift
Quick-fire facts
- •It runs roughly 6,000 km from the Beqaa Valley in Lebanon to Mozambique
- •The African section is properly the East African Rift System, with an Eastern (Gregory) and a Western (Albertine) branch
- •The Afar Triangle in Ethiopia is a triple junction where three rifts meet — the East African Rift, the Red Sea and the Gulf of Aden
- •Kilimanjaro, Mount Kenya and the Ngorongoro Crater are all rift volcanism
- •Lake Tanganyika, in the western branch, is the world's second-deepest and second-largest lake by volume after Baikal
- •Olduvai Gorge, Hadar, Laetoli, Lake Turkana and the Omo valley all lie along it
- •The Danakil Depression in the Afar is more than 100 m below sea level and among the hottest inhabited places on Earth
- •Common misconception: it is not one continuous valley — 'Great Rift Valley' is a 19th-century umbrella name for a set of separate but related rifts
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Sources
- John Walter Gregory — The Great Rift Valley: Being the Narrative of a Journey to Mount Kenya and Lake Baringo The 1896 work that gave the feature its name
- Mary Leakey — Olduvai Gorge: My Search for Early Man