Menengai Forest is an

urban forest An urban forest is a forest, or a collection of trees, that grow within a city, town or a suburb. In a wider sense, it may include any kind of woody plant vegetation growing in and around human settlements. As opposed to a forest park, whose eco ...

situated within the town of

Nakuru Nakuru is a city in the Great Rift Valley, Kenya, Rift Valley region of Kenya. It is the capital of Nakuru County, and was formerly the capital of Rift Valley Province. As of 2019, Nakuru had an urban and rural population of 570,674 inhabitant ...

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

. The

Menengai Crater Menengai Crater is a massive shield volcano with one of the biggest calderas in the world, in the Great Rift Valley, Kenya. It is the largest volcano caldera in Kenya and the second largest volcano caldera in Africa. Volcanic formed rich loam so ...

is within the forest. It was gazetted as a forest in the 1930s. It is surrounded by residential areas of Milimani Estate in the South, Ngachura and Bahati in the East,

Solai Solai is a town in Nakuru County, Kenya. It is located about thirty kilometers north of the county capital, Nakuru. Lake Solai lies to its north. Administratively, Solai is a location In geography, location or place are used to denote a regio ...

in the North and Olo-Rongai in the West. Various Government of Kenya facilities have been hived off from the forest; these include the

Kenya Broadcasting Corporation Kenya Broadcasting Corporation (KBC) is the state-run media organisation of Kenya. It broadcasts in English and Swahili, as well as in most local languages of Kenya. The corporation started its life in 1928 when Kenya was a British colony. I ...

and the Nakuru G.K Prison. There is also a geothermal exploration project by the

Geothermal Development Company The Geothermal Development Company (GDC) is a wholly owned parastatal of the Government of Kenya. It is mandated to execute surface geothermal development, including prospecting for, drilling, harnessing and selling geothermal energy to electri ...

inside the Menengai Crater floor.

Altitude

It is situated in an elevated area which ranges from above sea level.

Area

The forest covers an area of about . The actual forested area is about .

Flora

The main tree species in the forest are eucalyptus and acacia. Over 169 species of flowering plants and 17 species of grasses have been recorded in Menengai Forest. Example of flowering plants include leleshwa (''

Tarchonanthus camphoratus ''Tarchonanthus camphoratus'' (known as camphor bush for its scent, or leleshwa in Kenya), is a shrub or small tree, widespread in Africa south of the Sahel. Description The camphor bush can reach up to 6 meters in height. The twigs and younger ...

''), ''Euphorbia'' species and ''Acacia'' species. Common grasses in the forest include geothermal grass (''

Fimbristylis ''Fimbristylis'' is a genus of sedges. A plant in this genus may be known commonly as a fimbry or fimbristyle. There are 200 to 300 species distributed worldwide. Several continents have native species but many species have been introduced to ...

exilis'') and Boma

Rhodes grass ''Chloris gayana'' is a species of Poaceae, grass known by the common name Rhodes grass. It is native to Africa but it can be found throughout the tropical and subtropical world as a introduced species, naturalized species. It can grow in many t ...

Fauna

There are mammals, birds and insects. Mammal species include the

tree hyrax The tree hyrax or tree dassie is a small nocturnal mammal native to Africa. Distantly related to elephants and sea cows, it comprises the four species in the genus ''Dendrohyrax'', one of only three genera in the family Procaviidae, which is t ...

rock hyrax The rock hyrax (; ''Procavia capensis''), also called dassie, Cape hyrax, rock rabbit, and (in the King James Bible) coney, is a medium-sized terrestrial mammal native to Africa and the Middle East. Commonly referred to in South Africa as the das ...

olive baboon The olive baboon (''Papio anubis''), also called the Anubis baboon, is a member of the family Cercopithecidae Old World monkeys. The species is the most wide-ranging of all baboons, being native to 25 countries throughout Africa, extending from ...

, black-faced

vervet monkey The vervet monkey (''Chlorocebus pygerythrus''), or simply vervet, is an Old World monkey of the family Cercopithecidae native to Africa. The term "vervet" is also used to refer to all the members of the genus ''Chlorocebus''. The five distinct ...

mountain reedbuck The mountain reedbuck (''Redunca fulvorufula'') is an antelope found in mountainous areas of much of sub-Saharan Africa. Subspecies There are three recognized subspecies. * ''Redunca fulvorufula adamauae'' - Adamawa mountain reedbuck * ''Redunc ...

Kirk's dik-dik Kirk's dik-dik (''Madoqua kirkii'') is a small antelope native to Eastern Africa and one of four species of dik-dik antelope. It is believed to have six subspecies and possibly a seventh existing in southwest Africa. Dik-diks are herbivores, typi ...

and

slender mongoose The common slender mongoose (''Herpestes sanguineus''), also known as the black-tipped mongoose or the black-tailed mongoose, is a very common mongoose species native to sub-Saharan Africa. Taxonomy The scientific name ''Herpestes sanguineus'' ...

. Birds species include the

Verreaux's eagle Verreaux's eagle (''Aquila verreauxii'') is a large, mostly African, bird of prey. It is also called the black eagle, especially in southern Africa, not to be confused with the Indian black eagle (''Ictinaetus malayensis''), which lives far to t ...

(only found in Menengai Forest in Nakuru),

Abyssinian ground hornbill The Abyssinian ground hornbill or northern ground hornbill (''Bucorvus abyssinicus'') is an African bird, found north of the equator, and is one of two species of ground hornbill. It is the second largest species of African hornbill, only surpass ...

lesser spotted eagle The lesser spotted eagle (''Clanga pomarina'') is a large Eastern European bird of prey. Like all typical eagles, it belongs to the family Accipitridae. The typical eagles are often united with the buteos, sea eagles, and other more heavy-set Acc ...

African marsh harrier The African marsh harrier (''Circus ranivorus'') is a bird of prey belonging to the harrier genus ''Circus''. It is largely resident in wetland habitats in southern, central and eastern Africa from South Africa north to South Sudan. Description ...

Horus swift The Horus swift (''Apus horus'') is a small bird in the Swift (bird), swift family. Horus, whose name this bird commemorates, was the ancient Egyptian god of the sun, son of Osiris and Isis. Description The Horus swift is 13–15 cm long an ...

, turn-tailed ravens, red-winged sterling, and others. Other animals include spiders, molluscs and butterflies.

Soils

The forest stands on soils derived from volcanic ash. The soil texture is mainly sandy and is very easily eroded.

Management

The forest is under the management of the Kenya Forest Service in collaboration with the Menengai Community Forest Association

Menengai Crater

The

is found within the forest. The possible date of formation of the Menengai Caldera was during the third and last major faulting of the

Gregory Rift The Gregory Rift is the eastern branch of the East African Rift fracture system. The rift is being caused by the separation of the Somali plate from the Nubian plate, driven by a thermal plume. Although the term is sometimes used in the narrow s ...

valley in the middle

Pleistocene epoch The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

of the Quaternary period less than one million years ago. This major

faulting In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

resulted in very complex grid patterns, dropping the Rift valley a further approximately (from the original drops of approximately and with the first and second major faulting respectively). These latter minor faultings which both occurred during the upper Pleistocence led to the formation of new fractures and renewals on older fracture lines in Nakuru Basin and West of

Lake Nakuru Lake Nakuru is one of the Rift Valley lakes at an elevation of above sea level. It lies to the south of Nakuru, in the rift valley of Kenya and is protected by Lake Nakuru National Park. The lake's abundance of algae used to attract a vast qu ...

respectively. The first minor faulting was accompanied by the emission of

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of highly vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicular vol ...

showers from the Menengai Crater forming a pumice mantle, mainly on the western flank of Menengai. The pumice mantle forms a crudely stratified deposit, up to thick. The pumice mantle was originally believed to represent the first stage in the formation of a

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

of the

Krakatoa Krakatoa (), also transcribed (), is a caldera in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The caldera is part of a volcanic island group (Krakatoa archipelago) comprising four islands. Tw ...

n type. After reconsideration of the whole mechanism of caldera formation by comparing the form of Menengai with the form of the deeply eroded syenitic ring-complex west of

Oslo, Norway Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of i ...

it is now believed that cauldron subsidence and deep seated migration of

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

were contributing factors. The process is envisaged as: * Cauldron Subsidence - migration of magma at depth and fracturing of the retaining roof of the magma chamber * Sudden lowering of pressure resultant on subsidence - rapid release of gas. Catastrophic eruption of gas-charged pumice from numerous fissures formed by subsidence * Further collapse and engulfment of volcano super-structure - due to void formed by the evisceration process Near Menengai summit, a few ejected blocks of these black vitreous

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

are mixed with the pumice mantle on the outer slopes. To the south-west the lavas overlie the pumice mantle. The mode of origin of the pumice

lapilli Lapilli is a size classification of tephra, which is material that falls out of the air during a volcanic eruption or during some meteorite impacts. ''Lapilli'' (singular: ''lapillus'') is Latin for "little stones". By definition lapilli range f ...

eruptives is not certain, but stratification, sorting and lack of lithic inclusions suggest vulcanian showers rather than flowing avalanches, and their concentration to the west of Menengai suggest a control by wind direction. Later volcanic flows during the recent times (up to 2000 years ago) resulted in the formation of the Upper Menengai big lavas, which fill the caldera and are represented by trachyte lava flows and scoria cones. Trachyte lavas completely cover the floor of the caldera, concealing the rocks of the older volcano. The products of these late eruptions which are believed, from the complete absence of vegetation on some of the younger flows, to have continued up to the last few hundred years, have been described by McCall, 1957, p. 66.7. They form slaggy tongue- shaped flows emanating from various points in the caldera but mainly from the vicinity of the secondary summit and their flow was restricted by the caldera walls. They are characterized by beautifully developed pressure ridge patterns resembling those of a glacier. They include blocky flows apparently entirely composed of jumbled boulders, some massive flows, and also flows composed of twisted ropes of vitreous lavas. The lavas are characteristically black in colour and are for the most part vitreous, though they grade from nearly holocrystalline types to streaky obsidian. There are many conical piles of cinders of similar material within the caldera, but no well defined secondary crater. Similar cinder piles being products of their waning stage. These upper lavas are almost entirely restricted within the caldera but have spilled out over the caldera rim on the outer slopes at two points. The most conspicuous overspill is close to a line of small craterlets South-West of nakuru and there may be some genetic connection. The massive trachyte exposed in the Amolak Sigh Quarry is believed to belong to the upper lava series, though unlike most of these late lavas it is holocrystallive. The overspill probably represents one of the very earliest of these second series eruptions. The later lava seems to continue down the caldera wall into the caldera, and this may well be a ring feeder structure similar to the famous backward flow Crater Lake, USA,Williams, H. (1942) The Geology of the Crater Lake National Park, Oregon, p. 50–52 a ring feeder actually cut through by the caldera fault. Similar structures are seen in

Mount Suswa Mount Suswa is a shield volcano in the Great Rift Valley, Kenya. It is located between Narok and Nairobi, the capital of Kenya. The northwestern part of Mount Suswa is in Narok County, while the eastern and southern part are in Kajiado County. Th ...

caldera.

Gallery

Menengai Crater.jpg, Menengai Crater Menengai Crater 1.jpg, Menengai Crater Menengai Crater 3.jpg, Menengai Crater Menengai Crater 4.jpg, Menengai Crater Black Vitreous Lava.jpg, Black vitreous lava Menengai Forest Summit.jpg, Menengai Forest summit

References

{{coord, 0, 15, S, 36, 05, E, display=title, region:KE_type:forest_source:GNS-enwiki Nakuru Forests of Kenya