Lake Magadi
Encyclopedia
Lake Magadi is the southernmost lake in the Kenya
Rift Valley
, lying in a catchment of faulted volcanic rocks, north of Tanzania's Lake Natron
. During the dry season, it is 80% covered by soda
and is well known for its wading birds, including flamingo
s.
Lake Magadi is a saline, alkaline lake, approximately 100 square kilometers in size, that lies in a graben
. The lake is an example of a "saline pan". The lake water, which is a dense sodium carbonate
brine
, precipitates vast quantities of the mineral trona
(sodium sesquicarbonate). In places, the salt is up to 40 m thick. The lake is recharged mainly by saline hot spring
s (temperatures up to 86°C) that discharge into alkaline "lagoons" around the lake margins, there being little surface runoff
in this arid region. Most hot springs lie along the northwestern and southern shorelines of the lake. During the rainy season a thin (<1 m) layer of brine covers much of the saline pan, but this evaporates rapidly leaving a vast expanse of white salt that cracks to produce large polygons. A single species of fish, a cichlid
Alcolapia grahami
, inhabits the hot, highly alkaline waters of this lake basin and is commonly seen in some of the hot spring pools around the shoreline where the water temperature is less than 45°C.
Lake Magadi was not always so saline. Several thousand years ago (during the late Pleistocene
to mid-Holocene
) the Magadi basin held a freshwater lake with many fish, whose remains are preserved in the High Magadi Beds, a series of lacustrine and volcaniclastic sediments preserved in various locations around the present shoreline. Evidence also exists for several older Pleistocene precursor lakes that were much larger than present Lake Magadi. At times, Lake Magadi and Lake Natron
were united as a single larger lake.
Lake Magadi is also well known for its extensive deposits of siliceous chert
. There are many varieties including bedded cherts that formed in the lake and intrusive dike-like bodies that penetrated through overlying sediments while the silica was soft. Most famous is "Magadi-type chert", which formed from a sodium silicate mineral precursor magadiite
that was discovered at Lake Magadi during the 1960s.
Magadi
township lies on the lake
's east shore, and is home to the Magadi Soda factory, owned by Tata India since December 2005. This factory produces soda ash, which has a range of industrial uses.
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 in the film the shots are supposed to be at Lake Turkana
.
A causeway
that crosses the lake provides access to the area west of the lake (Nguruman Escarpment). There is no tourist accommodation at Magadi townsite.
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
Rift Valley
East African Rift
The East African Rift is an active continental rift zone in eastern Africa that appears to be a developing divergent tectonic plate boundary. It is part of the larger Great Rift Valley. The rift is a narrow zone in which the African Plate is in the process of splitting into two new tectonic plates...
, lying in a catchment of faulted volcanic rocks, north of Tanzania's Lake Natron
Lake Natron
Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of Africa's Great Rift Valley. The lake is fed by the Ewaso Ng'iro River but also by mineral-rich hot springs and is quite shallow, less than three meters deep, and varies in width depending...
. During the dry season, it is 80% covered by soda
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
and is well known for its wading birds, including flamingo
Flamingo
Flamingos or flamingoes are gregarious wading birds in the genus Phoenicopterus , the only genus in the family Phoenicopteridae...
s.
Lake Magadi is a saline, alkaline lake, approximately 100 square kilometers in size, that lies in a graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
. The lake is an example of a "saline pan". The lake water, which is a dense sodium carbonate
Sodium carbonate
Sodium carbonate , Na2CO3 is a sodium salt of carbonic acid. It most commonly occurs as a crystalline heptahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate is domestically well-known for its everyday use as a water softener. It can be extracted from the...
brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...
, precipitates vast quantities of the mineral trona
Trona
Trona ; Na3•2H2O is an evaporite mineral. It is mined as the primary source of sodium carbonate in the United States, where it has replaced the Solvay process used in most of the rest of the world for sodium carbonate production.- Etymology :The word "trona" comes to English by way of either...
(sodium sesquicarbonate). In places, the salt is up to 40 m thick. The lake is recharged mainly by saline hot spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...
s (temperatures up to 86°C) that discharge into alkaline "lagoons" around the lake margins, there being little surface runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
in this arid region. Most hot springs lie along the northwestern and southern shorelines of the lake. During the rainy season a thin (<1 m) layer of brine covers much of the saline pan, but this evaporates rapidly leaving a vast expanse of white salt that cracks to produce large polygons. A single species of fish, a cichlid
Cichlid
Cichlids are fishes from the family Cichlidae in the order Perciformes. Cichlids are members of a group known as the Labroidei along with the wrasses , damselfish , and surfperches . This family is both large and diverse. At least 1,300 species have been scientifically described, making it one of...
Alcolapia grahami
Alcolapia grahami
Alcolapia grahami is a vulnerable species of fish in the Cichlidae family. It is endemic to the hypersaline, warm Lake Magadi in Kenya, but has also been introduced to Lake Nakuru in Kenya and Lake Natron in Tanzania.-References:...
, inhabits the hot, highly alkaline waters of this lake basin and is commonly seen in some of the hot spring pools around the shoreline where the water temperature is less than 45°C.
Lake Magadi was not always so saline. Several thousand years ago (during the late Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
to mid-Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
) the Magadi basin held a freshwater lake with many fish, whose remains are preserved in the High Magadi Beds, a series of lacustrine and volcaniclastic sediments preserved in various locations around the present shoreline. Evidence also exists for several older Pleistocene precursor lakes that were much larger than present Lake Magadi. At times, Lake Magadi and Lake Natron
Lake Natron
Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of Africa's Great Rift Valley. The lake is fed by the Ewaso Ng'iro River but also by mineral-rich hot springs and is quite shallow, less than three meters deep, and varies in width depending...
were united as a single larger lake.
Lake Magadi is also well known for its extensive deposits of siliceous chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
. There are many varieties including bedded cherts that formed in the lake and intrusive dike-like bodies that penetrated through overlying sediments while the silica was soft. Most famous is "Magadi-type chert", which formed from a sodium silicate mineral precursor magadiite
Magadiite
Magadiite is a hydrous sodium silicate mineral which precipitates from alkali brines as an evaporite phase. It forms as soft white powdery monoclinic crystal masses. The mineral is unstable and decomposes during diagenesis leaving a distinctive variety of chert .The mineral was first described by...
that was discovered at Lake Magadi during the 1960s.
Magadi
Magadi, Kenya
Magadi, Kenya is a town in the Great Rift Valley at Lake Magadi, located southwest of Nairobi, in southern Kenya. Magadi is northeast of Lake Natron in Tanzania....
township lies on the lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
's east shore, and is home to the Magadi Soda factory, owned by Tata India since December 2005. This factory produces soda ash, which has a range of industrial uses.
The lake is featured in Fernando Meirelles's film The Constant Gardener
The Constant Gardener (film)
The Constant Gardener is a 2005 drama film directed by Fernando Meirelles. The screenplay by Jeffrey Caine is based on the John le Carré novel of the same name. It tells the story of Justin Quayle, a man who seeks to find the motivating forces behind his wife's murder.The film stars Ralph Fiennes,...
, which is based on the book of the same name
The Constant Gardener
The Constant Gardener is a 2001 novel by John le Carré. It tells the story of Justin Quayle, a British diplomat whose activist wife is murdered...
by John le Carré
John le Carré
David John Moore Cornwell , who writes under the name John le Carré, is an author of espionage novels. During the 1950s and the 1960s, Cornwell worked for MI5 and MI6, and began writing novels under the pseudonym "John le Carré"...
, although in the film the shots are supposed to be at Lake Turkana
Lake Turkana
Lake Turkana , 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...
.
A causeway
Causeway
In modern usage, a causeway is a road or railway elevated, usually across a broad body of water or wetland.- Etymology :When first used, the word appeared in a form such as “causey way” making clear its derivation from the earlier form “causey”. This word seems to have come from the same source by...
that crosses the lake provides access to the area west of the lake (Nguruman Escarpment). There is no tourist accommodation at Magadi townsite.