Lake Turkana
2008/9 Schools Wikipedia Selection. Related subjects: African Geography
| Lake Turkana Jade Sea |
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| Coordinates | |
| Lake type | Saline Monomictic Alkaline Endorheic |
| Primary inflows | Omo River Turkwel River Kerio River |
| Primary outflows | Evaporation |
| Catchment area | 130,860 km² |
| Basin countries | Ethiopia Kenya |
| Max. length | 290 km N-S |
| Max. width | 32 km, 20 mi E-W |
| Surface area | 6,405 km², 2473 mi² variable |
| Average depth | 30.2 m |
| Max. depth | 109 m |
| Water volume | 203.6 km³ |
| Surface elevation | 360.4 m |
| Islands | North Island, Central Island, South Island (volcanic) |
| Settlements | El Molo, Loyangalani, Kalokol, Eliye Springs, Ileret, Fort Banya. |
Lake Turkana (tər-kăn'ə, tʊr-kä'nə), formerly known as Lake Rudolf, is a lake in the Great Rift Valley in Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world's fourth largest salt lake after the Caspian Sea, Lake Issyk-Kul and the (shrinking) Aral Sea, and among all lakes it ranks twentieth. The water is potable but not palatable. It supports a rich lacustrine wildlife. The climate is hot and very dry.
The rocks of the surrounding area are predominantly volcanic. Central Island is an active volcano, emitting vapors. Outcrops and rocky shores are found on the East and South shores of the lake, while dunes, spits and flats are on the West and North, at a lower elevation.
On-shore and off-shore winds can be extremely strong as the lake warms and cools more slowly than the land. Sudden, violent storms are frequent. Three rivers (the Omo, Turkwel and Kerio) flow into the lake, but lacking outflow its only water loss is by evaporation. Lake volume and dimensions are variable. For example, its level fell by 10 meters between 1975 and 1993.
Due to temperature, aridity and geographic inaccessibility, the lake retains its wild character. Nile crocodiles are found in great abundance on the flats. The rocky shores are home to scorpions and carpet vipers. Although the lake and its environs have been popular for expeditions of every sort under the tutelage of guides, rangers and experienced persons, they certainly must be considered hazardous for unguided tourists.
Lake Turkana National Parks are now listed as a UNESCO World Heritage Site. Sibiloi National Park lies on the lake's eastern shore, while Central Island National Park and South Island National Park lie in the lake. Both are known for their crocodiles.
Demography
The lake was named Lake Rudolf (in honour of Crown Prince Rudolf of Austria) by Count Sámuel Teleki de Szék and his second-in-command Lieutenant Ludwig Ritter Von Höhnel, a Hungarian and an Austrian , in 1888. They were its first European discoverers, "finding" it on a large safari across East Africa on March 6, 1888. It was never really lost, of course, having long been known to the native tribes of the region. They include the Turkana, Rendille, Gabbra, Daasanach, Hamar Koke, Karo, Nyagatom, Mursi, Surma and Molo. For the location of many of these peoples refer to the dialect map in the article.
J. W. Gregory reported in The Geographical Journal of 1894 that it had been called 'Basso Narok'This means black lake in the samburu language and basso naibor for lake Stefanie meaning white lake in the samburu language. The samburu are among the dominant tribes in the lake Turkana region when the explorers came. . What the native form of this phrase was, what it might mean and in what language is not clear. The lake kept its European name during the colonial period of British East Africa. After the independence of Kenya, the president, Mzee Jomo Kenyatta, renamed it in 1975 after the Turkana, the predominant tribe there.
At some unknown time the lake became known as the Jade Sea from its turquoise color seen on approaching from a distance. The colour comes from algae that rise to the surface in calm weather. This is likely also a European name. The Turkana refer to the lake as anam Ka'alakol, meaning the sea of many fish. It is from the name Ka'alakol that Kalokol, a town on the western shore of Lake Turkana, east of Lodwar, derives its name. The area still sees few Western visitors, being a three-day drive from Nairobi, 400 km to the south.
Biology
Biomes
The major biomes are the lake itself, which is an aquatic biome, and the surrounding region, which is classified as Deserts and xeric shrublands. The desert is the Chalbi desert. During moister times a dry grassland appears, featuring Aristida adcensionis and A. mutabilis. During drier times the grass disappears. The shrublands contain dwarf shrubs, such as Duosperma eremophilum and Indigofera spinosa. Near the lake are doum palms.
Plankton
Both phytoplankton and zooplankton are found in the lake. Of the former the Cyanobacteria are represented by Microcystis aeruginosa; the Microalgae, Botryococcus braunii. Also present are Anabaenopsis arnoldii, Planctonema lauterbornii, Oocystis gigas, Sphaerocystis schroeteri, and some others. The zooplankton include copepods, Cladocera and Protozoa.
Fish
A number of species of native fish abound both in the demersal zone and the pelagic zone of the lake: the Alestiidae, or African tetras, a few genera of Cichlids, such as Tilapia, some species of bichir, an elephantfish ( Mormyridae), the African arowana, the African knifefish ( Gymnarchus niloticus), Distichodus niloticus of the Distichodontidae, as well as the Nile perch (Lates niloticus) and the Rudolph lates (Longispina), and numerous others. The lake has been heavily fished. The Norwegians built a fish factory there. During the early Holocene, the water level of lake Turkana was higher, and the lake overflowed into the Nile River, allowing fish and crocodiles access.
Birds
The Lake Turkana region is home to hundreds of species of birds endemic to Kenya. The East African Rift System also serves as a flyway for migrating birds, bringing in hundreds more. The birds are essentially supported by plankton masses in the lake, which also feed the fish.
Some birds more common to Turkana are the Little Stint, the Wood Sandpiper, and the Common Sandpiper. The African Skimmer (Rhyncops flavirostris) nests in the banks of Central Island. The White-necked Cormorant (Phalacrocorax africanus) ranges over the lake. The Greater Flamingo wades in its shallows. Heuglin's Bustard (Neotis heuglinii) is found in the east of the lake region.
Reptiles
The lake formerly contained Africa's largest population of Nile crocodiles: 14,000, as estimated in a 1968 study by Alistair Graham -- see the book 'Eyelids of Morning' for an excellent account of the Lake and its crocodiles.
Mammals
Over the dry grasslands ranges a frail population of grazing mammals and predators. The grazers are chiefly Grevy's zebra, Burchell's Zebra, the Beisa Oryx, Grant's Gazelle, the topi and the reticulated giraffe. They are hunted by the lion and the cheetah. Elephants and the black rhinoceros are no longer seen, although Teleki reported seeing (and shooting) many. Closer to the dust is the gerbil (Gerbillus pulvinatus).
Geology
Lake Turkana is an East African Rift feature. A rift is a weak place in the Earth's crust due to the separation of two tectonic plates, often accompanied by a graben, or trough, in which lake water can collect. The rift began when East Africa, impelled by currents in the mantle, began separating from the rest of Africa, moving to the northeast. Currently the graben is 320 km wide in the north of the lake, 170 km in the south. This rift is one of two, and is called the Great or Eastern Rift. There is another to the west, the Western Rift.
The basement rocks of the region have been dated by two analytical determinations to 522 and 510 million years ago (ma or mya). No rift was in the offing at that time. A rift is signalled by volcanic activity through the weakened crust. The oldest volcanic activity of the region occurred in the Nabwal Hills northeast of Turkana and is dated to 34.8 mya in the late Eocene.
The visible tectonic features of the region result from extensive extrusions of basalt over the Turkana-Omo basin in the window 4.18-3.99 mya. These are called the Gombe Group Basalts. They are subdivided into the Mursi Basalts and the Gombi Basalts.
The two latter basalts are identified as the outcrops that are the rocky mountains and badlands around the lake. In the Omo portion of the basin, of the Mursi Basalts, the Mursi Formation is on the west side of the Omo, the Nkalabong on the Omo, and the Usno and Shungura east of the Omo. Probably the best known of the formations are the Koobi Fora on the east side of Turkana and the Nachukui on the west.
Short-term fluctuations in lake level combined with periodic volcanic ash spewings over the region have resulted in a fortuitous layering of the ground cover over the basal rocks. These horizons can be dated more precisely by chemical analysis of the tuff. As this region is believed to have been an evolutionary nest of Hominins, the dates are important for generating a diachronic array of fossils, both Hominoid and non-Hominoid. Many thousands have been excavated.
Terraces representing ancient shores are visible in the Turkana basin. The highest is 75 m above the surface of the lake (only approximate, as the lake level fluctuates), which was current about 9500 years ago, at the end of the Pleistocene. It is generally theorized that Turkana was part of the upper Nile system at that time, connecting to Lake Baringo at the southern end and the White Nile in the north, and that volcanic land adjustments severed the connection. Such a hypothesis explains the Nile species in the lake, such as the crocodiles and the Nile Perch.
Anthropology
Around 2 million–3 million years ago, the lake was larger and the area more fertile, making it a centre for early hominins. Richard Leakey has led numerous anthropological digs in the area which have led to many important discoveries of hominin remains. The two-million-year-old Skull 1470 was found in 1972. It was originally thought to be Homo habilis, but some anthropologists have assigned it to a new species, Homo rudolfensis, named after the lake. In 1984, the Turkana Boy, a nearly complete skeleton of a Homo erectus boy was discovered by Kamoya Kimeu. More recently, Meave Leakey discovered a 3,500,000-year-old skull there, named Kenyanthropus platyops, which means "The Flat-Faced Man of Kenya".
The lake in popular culture
- The lake is featured in Fernando Meirelles's film The Constant Gardener, which is based on the book of the same name by John le Carré, although some of the footage was actually filmed at Lake Magadi.
- In the Kim Basinger movie I Dreamed of Africa (2000), the lake is briefly mentioned early in the film as Lake Rudolf and later as Lake Turkana.
- The lake is also featured in the video game series Xenosaga as being the location of an excavation to discover the original Zohar and the Anima Relics in the year A.D. 20XX.
- In his book A Lifetime with Lions, George Adamson (best known from the movie Born Free) describes various adventures along Lake Turkana, including a harrowing attempt to cross it in a makeshift raft.
- The travel writer John Hillaby describes a camel safari undertaken around the lake in his 1964 book Journey to the Jade Sea.
- Eyelids of the Morning: The Mingled Destinies of Crocodiles and Men by Alistair Graham and Peter Hill Beard; originally published in 1973 (New York Graphic Society - ISBN 0-8212-0464-5). For decades out of print, then back in print, currently out of print. Graham, who was the biologist of the team, writes a venerable account of a valuable, difficult, and gruesome scientific study; while Beard (when not catching crocodiles) took the dramatic photos, and designed this quirky, graphic coffee-table book. Together they spent a year on Lake Rudolf (now called Lake Turkana) studying crocs for ecological analysis. Additionally, it is an entrancing portrait of Turkana society.