Mountain Elgon is an extinct shield volcano on the border of Uganda and Kenya, north of Kisumu and west of Kitale. The mountain's highest point, named "Wagagai", is located entirely within Uganda. Although there is no verifiable evidence of its earliest volcanic activity, geologists estimate that Mount Elgon is at least 24 million years old, making it the oldest extinct volcano in East Africa. The mountain's name originates from its Maasai name, Elgonyi.
Physical features
Mount Elgon is a massive solitary volcanic mountain on the border of eastern Uganda and western Kenya. Its vast form, in diameter, rises above the surrounding plains. Its cooler heights offer respite for humans from the hot plains below, and its higher altitudes provide a refuge for flora and fauna.
Mt. Elgon consists of five major peaks: Wagagai (), in Uganda Sudek () on the Kenya/Uganda border Koitobos (), a flat-topped basalt column in Kenya Mubiyi () in Uganda Masaba () in Uganda
Other features of note are: The caldera — Elgon's is one of the largest intact calderas in the world. The warm springs by the Suam River Endebess Bluff () Ngwarisha, Makingeny, Chepnyalil, and Kitum caves: Kitum Cave is over wide and penetrates . The cave contains salt deposits and it is frequented by wild elephants that lick the salt exposed by gouging the walls with their tusks. Richard Preston's book The Hot Zone (1994) described the cave's association with the Marburg virus after two people who had visited it (one in 1980 and another in 1987) contracted the disease and died.
The mountain soils are red laterite. The mountain is the catchment area for the several rivers such as the Suam River, which becomes the Turkwel downstream and drains into Lake Turkana, and the Nzoia River and the Lwakhakha River, which flow to Lake Victoria. The town of Kitale is in the foothills of the mountain. The area around the mountain is protected by two Mount Elgon National Parks, one on each side of the international border.
Fauna
A population of African bush elephants is present around the mountain that ventures deep into caves to access salt licks. This population was formerly present around all the mountain, but has since been reduced to the Kenyan side, where they venture into Kitum Cave.
There are several disjunct populations of mammal species that are restricted to Mount Elgon, including the Elgon shrew (Crocidura elgonius), Rudd's mole-rat (Tachyoryctes ruddi), and Thomas's pygmy mouse (Mus sorella). There are also several disjunct populations of rare bird species, including Sharpe's longclaw (Macronyx sharpei), Hunter's cisticola (Cisticola hunteri), Jackson's spurfowl (Pternistis jacksoni), and the Elgon francolin (Scleroptila elgonensis).
An endemic subspecies of the bushbuck (Tragelaphus scriptus heterochrous) is restricted to the mountain. The possibly extinct Du Toit's torrent frog (Arthroleptides dutoiti), considered an EDGE species due to its evolutionary distinctiveness, is known only from a single specimen collected on the Kenyan side of the mountain.
Flora
Some rare plants are found on the mountain, including Ardisiandra wettsteinii, Carduus afromontanus, Echinops hoehnelii, Ranunculus keniensis, and Romulea keniensis.
Local ethnicities
Mount Elgon and its tributaries are home to five tribes: the Bukusu, the Bagisu, the Sapinjek, the Sabaot, and the Ogiek, better known in the region under the derogatory umbrella term Ndorobo.