Great Rift Valley and Rift Valley Lakes
Geography › Geomorphic Movements and Plate Tectonics · Topic 3.11
The Great Rift Valley is a vast system of rifts stretching about 6,000 km from the Jordan Valley and the Red Sea through East Africa to Mozambique. Its East African Rift branches hold long, deep rift valley lakes such as Tanganyika, Malawi, Turkana and Albert, and the system is slowly splitting the Somali plate from the Nubian plate, a process that may eventually create a new ocean.
5 min read · UPSC Prelims · Geography · Geomorphic Movements and Plate Tectonics
At a Glance
- Length About 6,000 km, Jordan to Mozambique
- Eastern branch Gregory Rift; lakes Turkana, Naivasha, Natron
- Western branch Albertine Rift; lakes Tanganyika, Malawi, Albert, Kivu
- Plates splitting Somali from Nubian, at a few mm a year
- Key feature Long, narrow, deep lakes and volcanoes
- Exam link UPSC Prelims, Geography: Geomorphic Movements and Plate Tectonics
Where Does It Fit?
This is the last topic of the category on geomorphic movements and plate tectonics. The previous topic explained divergent boundaries and how rift valleys form. The next category begins with the classification of mountains. Previous topic: Divergent Boundaries and Rift Valleys. Next topic: Classification of Mountains – Fold, Block and Volcanic.
What Is the Great Rift Valley?
In short: it is a 6,000-km-long scar across East Africa and the Middle East where the Earth’s crust is splitting.
The Great Rift Valley, named by the Scottish geologist John Walter Gregory in 1893, is a continuous series of rift valleys that runs from the Jordan Valley in West Asia, through the Red Sea and the Afar region of Ethiopia, down through East Africa to Mozambique. The African part is known as the East African Rift System. The rift is a divergent boundary, where the Somali plate and the Nubian plate are moving apart at only a few millimetres a year, a process described in Divergent Boundaries and Rift Valleys. Geologists suggest that, over millions of years, the Horn of Africa may separate from the rest of the continent and a new ocean may form, although this is a very slow and uncertain process.
What Are the Two Branches of the East African Rift?
| Branch | Region | Features |
|---|---|---|
| Eastern (Gregory) Rift | Ethiopia, Kenya, Tanzania | Volcanic; Lakes Turkana, Baringo, Nakuru, Naivasha, Magadi, Natron; Mount Kenya and Kilimanjaro nearby |
| Western (Albertine) Rift | Uganda, DR Congo, Rwanda, Tanzania, Zambia, Malawi, Mozambique | Very deep lakes: Albert, Edward, Kivu, Tanganyika, Malawi (Nyasa); Rwenzori Mountains |
Lake Victoria, the largest lake of Africa, lies between the two branches on a plateau and is not a rift lake. It is shallow, with a maximum depth of about 80 m. The Afar Triangle, in the north, is a triple junction where the Red Sea, Gulf of Aden and East African rifts meet; it includes the Danakil Depression, one of the hottest and lowest places on the Earth, about 125 m below sea level, with volcanoes and salt flats.
Which Are the Important Rift Valley Lakes?
Rift valley lakes are long, narrow and very deep, because they fill fault-bounded troughs with steep sides.
| Lake | Key facts |
|---|---|
| Tanganyika | Longest freshwater lake in the world, about 670 km, and the second deepest, about 1,470 m; shared by Tanzania, DR Congo, Burundi and Zambia |
| Lake Malawi (Nyasa) | Very deep with extraordinary diversity of cichlid fish; shared by Malawi, Mozambique and Tanzania |
| Turkana | Largest permanent desert lake and the largest alkaline lake in the world, in northern Kenya |
| Albert, Edward, Kivu | Western rift lakes; Kivu is notable for dissolved gases |
| Natron, Magadi, Nakuru | Soda or alkaline lakes in the east; home to flamingos |
Outside Africa, Lake Baikal in Siberia, the deepest lake in the world at about 1,640 m, and the Dead Sea, whose shore is the lowest land elevation on Earth at about 430 m below sea level, are also rift valley lakes. The Dead Sea is a salt lake in the Jordan rift.
What Volcanoes and Other Features Occur Along the Rift?
Magma rising along the faults formed volcanoes along the rift. Mount Kilimanjaro in Tanzania, at about 5,895 m the highest peak of Africa, and Mount Kenya, at about 5,199 m, are volcanic mountains near the eastern rift, and Ol Doinyo Lengai in Tanzania is the only active volcano that erupts natrocarbonatite lava, which is rich in carbonates. The rift is also important in human history, since fossils of early humans, including those at Olduvai Gorge in Tanzania, have been found in its sediments, and the region is often called a cradle of humankind. As an analytical point, rift lakes create rich fisheries and fertile volcanic soils, so the rift is densely populated, but this also places millions of people near earthquake and volcanic hazards.
Why Is This Topic Important?
- Map-based Lake locations asked
- Concept Living example of rifting
- Comparisons Links to Indian rifts
What Came Next?
The next category begins with the classification of mountains. The first topic is Classification of Mountains – Fold, Block and Volcanic.
Key People and Terms
- Great Rift Valley Rift system from Jordan to Mozambique
- Gregory Rift Eastern branch in Kenya
- Albertine Rift Western branch
- Afar Triangle Triple junction in Ethiopia
- Natrocarbonatite Carbonate-rich lava
- Danakil Depression Hot low basin in Afar
Exam Corner
Points to Remember
- The Great Rift Valley is about 6,000 km long.
- Tanganyika is the longest freshwater lake.
- Baikal is the deepest lake; Dead Sea the lowest shore.
- Lake Victoria is not a rift lake.
- Kilimanjaro is the highest peak of Africa.
Do Not Confuse With
- Lake Victoria and Lake Tanganyika Plateau lake versus rift lake
- Eastern and Western Rift Volcanic versus deep lakes
- Dead Sea and Baikal Lowest shore versus deepest lake
Memory Hook
Tanganyika long and deep, Victoria shallow in between; two arms of the rift hold the lakes.
Mains Angle
Questions ask for features and processes. These points add depth.
- Process Divergent boundary on land
- Lakes Long, deep, narrow
- Future Possible new ocean
A Question You May Face
An original practice question, not a past paper question.
“Describe the Great Rift Valley of Africa and explain the formation of its lakes.”
How to Answer
- Location Jordan to Mozambique.
- Process Faulting and stretching.
- Lakes Tanganyika, Malawi.
- Future Possible split of Africa.
GS Relevance
Frequently Asked Questions
What is the Great Rift Valley?
The Great Rift Valley is a continuous series of rift valleys that stretches about 6,000 km from the Jordan Valley and the Red Sea through East Africa to Mozambique. It is a divergent plate boundary where the Somali and Nubian plates are slowly moving apart.
Which are the main rift valley lakes of Africa?
The main rift valley lakes include Tanganyika, Malawi (Nyasa), Albert, Edward and Kivu in the western branch, and Turkana, Baringo, Naivasha, Nakuru and Natron in the eastern branch. They are long, narrow and very deep because they fill faulted troughs.
Is Lake Victoria a rift valley lake?
No. Lake Victoria lies on a plateau between the eastern and western branches of the East African Rift, and it is a shallow lake with a maximum depth of about 80 m. It is the largest lake of Africa but not a rift lake.
Which is the deepest lake in Africa?
Lake Tanganyika is the deepest lake in Africa, at about 1,470 m, and the second deepest in the world after Lake Baikal. It is also the longest freshwater lake, at about 670 km, and lies in the western branch of the rift.
Will Africa split into two?
The East African Rift is slowly pulling the Somali plate away from the Nubian plate by a few millimetres a year. If the process continues for millions of years, the Horn of Africa could separate and a new ocean could form, but the outcome is uncertain.
PYQ Practice — Statement Analysis
1 Lake Tanganyika is a rift valley lake.
It lies in the western rift.
2 Lake Victoria lies within the Great Rift Valley.
It lies on a plateau between its two branches.
3 Lake Baikal is the deepest lake in the world.
It is about 1,640 m deep.
4 Mount Kilimanjaro is the highest peak of Africa.
It is a volcanic mountain in Tanzania.
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