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Rift Valley Province
—  Province  —
Rift Valley
Location in Kenya.
Coordinates: 0°30′N 36°0′E / 0.5°N 36°E / 0.5; 36Coordinates: 0°30′N 36°0′E / 0.5°N 36°E / 0.5; 36
Country	Kenya
No. of districts:	36
Capital	Nakuru
Area
• Total	182,413 km2 (70,430 sq mi)
Population (2009)
• Total	10,006,805
• Density	55/km2 (140/sq mi)
Time zone	EAT (UTC+3)

Rift Valley Province of Kenya, bordering Uganda, is one of Kenya's seven administrative provinces outside Nairobi. Rift Valley Province is the largest and one of the most economically important provinces in Kenya. It is dominated by the Kenya Rift Valley which passes through it and gives the province its name. According to the 1999 Census, the province covers an area of 173,854 square kilometres (42,960,000 acres; 67,125 sq mi) and has a population of 8,786,300 inhabitants (2007),^{[citation needed]} making it the largest and most populous province in the country. The capital is the town of Nakuru.

Geography[link]

Geographical map of Kenya

The Great Rift Valley runs south through Kenya from Lake Turkana in the north and has several unique geographical features, including the Elgeyo escarpment which is a popular tourist attraction.

Apart from the Rift Valley itself, the area has other important geographic features such as: the extinct volcanoes Mount Longonot and Mount Suswa and Lake Baringo, Lake Bogoria, Lake Magadi, Lake Nakuru, Lake Naivasha, the Suguta Valley, and Lake Turkana.

Geology[link]

A large part of Kenya is underlain by Precambrian basement, while the Kenya rift basin (a typical extensional basin) hosts Tertiary volcanics that cover Mesozoic sediments (Recently these sediments have been considered for oil exploration ^[1]). The sedimentary basins evolved along the Anza trough during the Late Paleozoic to Early Tertiary times through extension tectonics during the major Gondwanaland breakup. In the Miocene Period the region underwent intermittent uplift and subsidence along major boundary faults accompanied by the large outpouring of lava flows. The Anza trough intersects the modern rift valley in the area of Lake Turkana. Rifting still continues today; primarily in the north, where active volcanoes are more plentiful.

Economy[link]

The highlands provide adequate rainfall for farming and agriculture which is the economic base of the residents of the Rift Valley. Tea from the highlands in the Kericho district enjoy a world wide reputation, but horticulture is an important part of the district's economy and cattle raising is also practised to a large extent.

The full economic potential of the Rift Valley region is, however, far from fully exploited, though the current growth in population and improved education may change this in a near future. People in the province are still mostly rural, but urbanisation is gradually increasing; new cities and towns contain the rural-urban migration and, provided the right policies are instituted, the Rift Valley province will be able to emerge as a national economic and cultural hub.

Ethnicity[link]

The people of the Rift Valley are a mesh work of different tribal identities, and the Kalenjin and the Maasai are two of the best known ethnic groups. Most of Kenya's top runners comes from the Kalenjin community. The Maasai people have the most recognizable cultural identity, both nationally and internationally, and serve as Kenya's international cultural symbol.

Districts[link]

District (capital):
Baringo (Kabarnet) · Bomet (Bomet) · Buret (Litein) · Kajiado (Kajiado) · Keiyo (Iten / Tambach) · Kericho (Kericho) · Koibatek (Eldama Ravine) · Laikipia (Nanyuki) · Marakwet Kapsowar) · Nakuru (Nakuru) · Nandi (Kapsabet) · Narok (Narok) · Samburu (Maralal) · Trans Mara (Kilgoris) · Trans-Nzoia (Kitale) · Turkana (Lodwar) · Uasin Gishu (Eldoret) · West Pokot (Kapenguria)

Districts after 2007[link]

Several new districts have been created since 2007 in Kenya, also in Rift Valley Province ^[2]:

See also[link]

• Kerio River
• Zeitz Foundation

References[link]

v t e First- and second-level administrative divisions of Kenya Provinces Central Coast Eastern Nairobi North Eastern Nyanza Rift Valley Western Principal cities and towns Baragoi Bungoma Busia Eldoret Embu Garissa Hola Homa Bay Isiolo Kajiado Kakamega Kapenguria Kericho Kiambu Kilifi Kisii Kisumu Kitale Kitui Limuru Lodwar Lokichokio Loiyangalani Lamu Machakos Malindi Mandera Maralal Marsabit Meru Mombasa Moyale Mumias Murang'a Nairobi Naivasha Nakuru Namanga Nanyuki Narok Nyahururu Nyeri Ruiru Thika Voi Wajir Webuye Wundanyi Districts Baringo Bomet Bondo Bungoma Buret Busia Butere/Mumias Embu Garissa Gucha Homa Bay Ijara Isiolo Kajiado Kakamega Keiyo Kericho Kiambu Kilifi Kirinyaga Kisii Kisumu Kitui Koibatek Kuria Kwale Laikipia Lamu Lugari Machakos Makueni Malindi Mandera Maragua Marakwet Marsabit Mbeere Meru Central Meru North Meru South Migori Mombasa Mount Elgon Moyale Muranga Mwingi Nairobi Nakuru Nandi Narok Nyamira Nyandarua Nyando Nyeri Rachuonyo Samburu Siaya Suba Taita-Taveta Tana River Teso Tharaka Thika Trans Mara Trans-Nzoia Turkana Uasin Gishu Vihiga Wajir West Pokot

Following the national referendum held on August 4, 2010, a new structure of governance which in effect banned existing provinces was introduced. In the place of provinces, 47 counties were created.^{[citation needed]}

African Rift Valley. From left to right: Lake Upemba, Lake Mweru, Lake Tanganyika (largest), and Lake Rukwa.

The Ottawa-Bonnechere Graben

A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion. When the tensional forces are strong enough to cause the plate to split apart it will do so such that a center block will drop down relative to its flanking blocks, forming a graben. This creates the nearly parallel steeply dipping walls. This feature is the beginning of the rift valley. As this process continues, the valley gets wider and wider until it becomes a large basin that fills with sediment from the rift walls and the surrounding area. One of the better long term examples of this process is the Basin and Range province in Nevada and Utah. Rifts can occur at all elevations, from the sea floor to plateaus and mountain ranges. They can occur in continental crust or in oceanic crust. Rift valleys are often associated with a number of adjoining subsidiary or co-extensive valleys which are typically considered geologically part of the principal rift valley.

The most extensive rift valley is located along the crest of the mid-ocean ridge system and is the result of sea floor spreading. Examples of this type of rift include the Mid-Atlantic Ridge and the East Pacific Rise.

Many existing continental rift valleys are the result of a failed arm (aulacogen) of a triple junction, although there are two, the East African Rift and the Baikal Rift Zone, which are currently active, as well as a third which may be, the West Antarctic Rift. In these instances, not only the crust, but also entire tectonic plates are in the process of breaking apart to create new plates. If they continue, continental rifts will eventually become oceanic rifts.

Other rift valleys are the result of bends or discontinuities in horizontally-moving (strike-slip) faults. When these bends or discontinuities are in the same direction as the relative motions along the fault, extension occurs. For example, for a right lateral-moving fault, a bend to the right will result in stretching and consequent subsidence in the area of the irregularity. In the view of many geologists today, the Dead Sea lies in a rift which results from a leftward discontinuity in the left lateral-moving Dead Sea Transform fault. Where a fault breaks into two strands, or two faults run close to each other, crustal extension may also occur between them as a result of differences in their motions. Both types of fault-caused extension commonly occur on a small scale, producing such features as sag ponds or landslides.

Rift valley lakes[link]

The largest freshwater lakes in the world are all located in rift valleys.^[1] Lake Baikal in Siberia, a World Heritage Site,^[2] lies in an active rift valley. Baikal is both the deepest lake in the world and, with 20% of all of the liquid freshwater on earth, has the greatest volume.^[3] Lake Tanganyika, second by both measures, is in the Albertine Rift, the westernmost arm of the active East African Rift. Lake Superior in North America, the largest freshwater lake by area, lies in the ancient and dormant Midcontinent Rift. The largest subglacial lake, Lake Vostok, may also lie in an ancient rift valley.^[4] Lake Nipissing and Lake Timiskaming in Ontario and Quebec, Canada lie inside a rift valley called the Ottawa-Bonnechere Graben.^[5] Þingvallavatn, Iceland's largest natural lake, is also an example of a rift lake.

References[link]

1. ^ "The World's Greatest Lakes". Archived from the original on 2006-11-27. http://web.archive.org/web/20061127174949/http://www.schoolofflyfishing.com/resources/worldslakes.htm. Retrieved 2007-01-07. 
2. ^ "Lake Baikal – World Heritage Site". World Heritage. http://whc.unesco.org/en/list/754. Retrieved 2007-01-13. 
3. ^ "The Oddities of Lake Baikal". Alaska Science Forum. http://www.gi.alaska.edu/ScienceForum/ASF9/986.html. Retrieved 2007-01-07. 
4. ^ Siegert, Martin J. (1999). "Antarctica's Lake Vostok". American Scientist 87 (6): 510. DOI:10.1511/1999.6.510. http://www.americanscientist.org/template/AssetDetail/assetid/15820/page/3;jsessionid=baa9...#26308. Retrieved 2007-12-12. "The best explanation is that Lake Vostok may lie in a rift valley, as does Lake Tanganyika in East Africa and Lake Baikal in Russia. The geography of Lake Vostok is indeed consistent with this notion, in that the lake has a crescent shape, just like Tanganyika and Baikal, and the side walls of the lake are relatively steep, at least on one side." ^{[dead link]}
5. ^ John Grotzinger .... (2006). Understanding Earth.. New York: W. H. Freeman. ISBN 0-7167-7696-0. 

Further reading[link]

• Bonatti, E., 1985. Punctiform initiation of seafloor spreading in the Red Sea during transition from a continental to an oceanic rift. Nature, 316: 33–37.
• Mart, Y., Dauteuil, O., 2000. Analogue experiments of propagation of oblique rifts. Tectonophysics, 316: 121–132.