TheGreat Rift Valley is part of an intra-continental system of topographic depressions that runs throughKenya from north to south. It is part of theGregory Rift, the eastern branch of theEast African Rift, which starts inTanzania to the south and continues northward intoEthiopia.[1] It was formed on the "Kenyan Dome", a geographical upwelling created by the interactions of three majortectonic plates: theArabian,Nubian, andSomali plates.[2] In the past, it was seen as part of a "Great Rift Valley" that runs fromMozambique toSyria. Most of the valley falls within the formerRift Valley Province.
The valley contains theCherangani Hills and a chain of volcanoes, some of which are still active.The climate is mild, with temperatures usually below 28 °C (82 °F).Most rain falls during the March–June and October–November periods.[3]The Tugen Hills to the west of Lake Baringo contain fossils preserved in lava flows from the period 14 to 4 million years ago. The relics of many hominids, ancestors of humans, have been found here.[4]
The valley is bordered byescarpments to the east and west. The floor is broken by volcanoes, some still active, and contains a series of lakes. Some of the soils areAndisols, fertile soils from relatively recent volcanic activity.
Lake Turkana occupies the northern end of the Great Rift Valley in Kenya. There are also volcanoes in Lake Turkana. TheSuguta Valley, or Suguta Mud Flats, is an arid part of the Great Rift Valley directly south ofLake Turkana. Theshield volcanoEmuruangogolak straddles the valley to the south of Suguta, and further southMount Silali andPaka rise from the valley floor. Paka is a shield volcano, with widespread geothermal activity. South of Paka areMount Korosi,Lake Baringo andLake Bogoria.Menengai is a massive shield volcano in the floor of the rift with a caldera that formed about 8,000 years ago.[5] It overlooksLake Nakuru to the south.This region also includesLake Elementaita,Mount Kipipiri andLake Naivasha.
TheHell's Gate National Park lies south ofLake Naivasha.[6] In the early 1900s,Mount Longonot erupted, and ash can still be felt around Hell's Gate.[7] Mount Longonot is a dormant stratovolcano located southeast ofLake Naivasha.Mount Suswa is a shield volcano located betweenNarok andNairobi. Lava flows from the most recent eruptions are still not covered by vegetation, and may be no more than one hundred years old.[8]Lake Magadi is the most southern rift valley lake in Kenya, although the northern end ofLake Natron in Tanzania reaches into Kenya.
TheElgeyo escarpment forms part of the western wall. TheKerio Valley lies between theTugen Hills and the Elgeyo escarpment at an elevation of 1,000 metres (3,300 ft).There are large deposits ofFluorite in theKerio Valley area.Further south theMau Escarpment is a steep natural cliff approximately 1,000 m (3,300 ft) high, running along the western edge of the Great Rift Valley aboutLake Naivasha.Yet further south theNguruman Escarpment is around 50 kilometers long and elongated in N-W direction. Its northern edge is about 120 kilometres (75 mi) southwest of Nairobi, while the southern edge is near the Tanzanian border, at the northwestern corner ofLake Natron.TheAberdare Range forms a section of the eastern rim of the Great Rift Valley to the north of Nairobi.Mount Satima lies at the northern end of the Aberdares and is their highest point, andMount Kinangop at the southern end is the second highest. The mountains form a ridge between these two peaks.Ngong Hills are peaks in a ridge along the east of the Great Rift Valley, located southwest near Nairobi.
| UNESCO World Heritage Site | |
|---|---|
 Lake Bogoria, one of the main lakes in the Great Rift Valley. | |
 Interactive map of Kenya Lake System in the Great Rift Valley | |
| Location | Rift Valley Province,Kenya |
| Includes | |
| Criteria | Natural: (vii), (ix), (x) |
| Reference | 1060rev |
| Inscription | 2011 (35thSession) |
| Area | 32,034 ha (79,160 acres) |
| Buffer zone | 3,581 ha (8,850 acres) |
| Coordinates | 00°26′33″N36°14′24″E / 0.44250°N 36.24000°E /0.44250; 36.24000 |
 Interactive map of Great Rift Valley, Kenya | |
| Official name | Lake Turkana National Parks |
| Criteria | Natural: viii, x |
| Reference | 801bis |
| Inscription | 1997 (21stSession) |
| Extensions | 2001 |
  Great Rift Valley, Kenya Location of Great Rift Valley, Kenya in Kenya | |
Kenya is home to 64 (9.50%) of the total lakes found within the continent of Africa.[9] Eight of these make up the main lakes in the Kenyan Rift Valley. From north to south, the names of these lakes areLake Turkana,Lake Logipi,Lake Baringo,Lake Bogoria,Lake Nakuru,Lake Elmenteita,Lake Naivasha, andLake Magadi.[3] Of those eight, only Lakes Baringo and Naivasha are fresh water.[10]
Lake Turkana, at the northern end of the rift, is 250 kilometres (160 mi) long, between 15 kilometres (9.3 mi) and 30 kilometres (19 mi) wide and is 125 metres (410 ft) at its greatest depth.[11]Most of the other lakes are shallow and poorly drained, and therefore have become alkaline. They have waters that are rich in blue-green algae, which feed insect larvae, small crustaceans andlesser flamingos. The larvae and crustaceans are food for fish andgreater flamingos.[3]Massive flocks of these birds have been found to have an effect on the lakeside sediments also. Their numbers cause trampling of the silts in certain areas, while the feeding grounds are oxygenated due to probing beaks in the mud. Their nest mounds can also be preserved and cemented as the lake's water levels change. These form irregularities in the lakeside topography.[12]
Trona, an evaporative mineral, used for sodium carbonate production, has been mined atLake Magadi for nearly 100 years. It produces about 250,000 metric tonnes per year.[13] Other precious minerals like rubies and pink sapphires have been found and mined from areas around Lake Baringo. In 2004, over 2 kilograms ofCorundum were collected.[14]
Three shallow alkaline lakes and the surrounding lands make up the Kenya lake system:Lake Bogoria at 10,700 hectares (26,000 acres),Lake Nakuru at 18,800 hectares (46,000 acres) andLake Elmenteita at 2,534 hectares (6,260 acres). This system has one of the most diverse populations of birds in the world, and is the home of thirteen globally threatened species of bird. It is an important nesting and breeding site forgreat white pelicans, and is the most important feeding area for lesser flamingos in the world. The system is home to globally important populations ofblack-necked grebe,African spoonbill,pied avocet,little grebe,yellow-billed stork,black-winged stilt,grey-headed gull andgull-billed tern.[15]
The Kenya lake system is a key location on theWest Asian-East African Flyway, a route followed by huge numbers of birds in their annual migration from breeding grounds in the north to wintering places in Africa. The lands around the lakes include large populations of black rhino, Rothschild's giraffe, greater kudu, lion, cheetah and wild dogs.The Kenya lake system is surrounded by the steep escarpment of the Rift Valley, which provides a spectacular backdrop.[15]
Other lakes areLake Chew Bahir, in the northeast extension. This lake lies mainly in Ethiopia but extends into Kenya in the rainy season.Lake Kamnarok is another small lake.
![Sketch by John Walter Gregory from his expedition to East Africa in 1892-3. "[Mount] Kenya from the Kapte Plains west of Machakos"](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aGregory002.jpg)
