The Aberdare Range forms a section of the eastern rim of the Great Rift Valley running roughly north to south. On the west, the range falls off steeply into the Kinangop Plateau and then into the Great Rift Valley. On the east, the range slopes more gently. Lake Naivasha and the distant Mau Escarpment can be seen from peaks in the range.
The range has a maximum elevation of 3,999 metres (13,120 ft) above sea level and is heavily forested. The former name of the range survives in Mount Satima ("the mountain of the young bull"), the highest peak in the Aberdare Range. The second-highest peak, at the southern end of the range, is Mount Kinangop at 3,906 metres (12,815 ft). Mount Kenya, 5,199 metres (17,057 ft) the second highest mountain in Africa after Kilimanjaro lies east of the Aberdare Range.
The Aberdares are the water catchment area for the Sasumua dam and the Ndakaini dam, which provide most of the water for Nairobi. The mountain forests are catchment areas for the Tana River, the largest river in Kenya, supplying water to the Seven Forks hydroelectric power complex which generates over 55 percent of Kenya’s total electricity output.
The main ecosystems within the mountain range are rainforest giving way to dense bamboo forests and then moorland. The steep western edges of the hillside are sparsely inhabited by wildlife compared to the forested gentle slopes to the east, which are home to a wide variety of wildlife. There are multitudes of elephant, buffalo, giant forest hog as well as the endangered black rhino. A variety of cats including leopards and the rare African golden cat. Other threatened species including the Jackson mongoose, the black and white colobus monkey and Sykes' monkey are plentiful, as are waterbuck, reedbuck, duikers, serval cats and bushbuck.
The Aberdares contain a rich diversity of vegetation. There are 778 vegetation and plant species, subspecies and varieties found in the Aberdare National Park, due to the park's altitude and rainfall. Hardwood trees include camphor, cedar, podo and hagenia.
Much of the range has been protected within the Aberdare National Park since its creation in 1950. The range attracts large numbers of hikers and climbers operating out of the main centers of Naivasha and Gilgil. The lower slopes are farmed, higher areas are known for their wildlife. The Rhino Charge is an annual event run by conservationists in Kenya to pay for fencing of the Aberdare National Park as a means of protecting East Africa's largest indigenous forest from destruction.
Aberdare Ranges Forest are the host for the Aberdare Forest Reserve, which along with the Kikuyu Escapements run 120 km northwards from Nairobi and about 40 km at its widest point. With a perimeter of 566 km, the Aberdare Ranges vary in attitude from 2000 meters on the forest boundary on the eastside and 4,001 meters towards the northern edge at the peak of Oldonyo Lesatima. The Ranges descend gradually from the peak towards Nyahururu from the northern side, where incised river valleys and volcanic vents are evident. On the southern side, the ranges are steep southwards from IL Kinangop peak towards the northern part of Murang’a North District.
The major rivers from Aberdare Forest are Athi and Tana, which flow into the India Ocean, Ewaso Nyiro that drains into Lorian Swamp and River Malewa that drains into Lake Naivasha. The ranges also have several tributaries, and higher up are bog markings that are the source of the rivers on the moorlands and afro-alpine. The Athi, Lake Naivasha, Tana and Ewaso Nyiro river basins have their source in Aberdare Forest Reserve.
Epidemic plants on the forest include lobelia deckeniisspsattimae, helichrysum gloria-dei and Alchemilla hageniae. The forest has four vegetation zones including subalpine vegetation, xeromorphic evergreen forest, montane humid forest, and submontane forest.
This found at an altitude of 3,300 m and above, which is the moorlands. Alpine grass (Deschampsia), distinguished by giant groundsell (Dendrosenecio johnstonii), Lobelia deckenii, and heath (Erica excelsa). Moorland communities are the main vegetation on this region. Shrub community consisting of Erica arborea and Hebenstretia angolensis are found between 3,000 m and 3,300 m, while a belt of bamboo is common between 2,400 and 3,300 m, and cover about 35,000 ha.
This belt is mostly dominated by pioneer species Macaranga capensis and Newbutonia macrocalyx and runs to the east side of the range. The region is also host to the valuable commercial species including Aningeria adolfi-friederici, Ocotea usambarensis and Syzygium guineense, which are the most conspicuous forest in the Kikuyu escarpment.
Located on the dry northern and western slopes of Aberdares, it has several species with the most notable being the olives (Olea europaea, Olea capensis, Olea hochstetteri), podo (Podocarpus latifolius), and cedar (Juniperus procera).
This forms the seasonal forest cover on the north-east slopes with predominantly Ekebergia capensis, Nuxia congesta, Cassipourea malossana and Calodendrum capense (Cape chestnut) species.
The Aberdare Range was named by Joseph Thomson in 1884 in honour of Lord Aberdare, who at the time was President of the Royal Geographical Society and the Royal Historical Society. Aberdare was also a Liberal politician who had served as Home Secretary from 1868 to 1873. He was later to become the first Chancellor of the University of Wales.
The area is well known as the headquarters of Dedan Kimathi, leader of the 1950s Mau Mau Uprising. Also, Elizabeth II became Queen of the United Kingdom while vacationing in the Aberdares. It was also the site where J.A. Hunter killed the rogue elephant of Aberdare Forest.