The local name by Kikuyu is Nyandarua, meaning “the drying hide”. As a result of its distinctive appearance of unending folds of its silhouette. The Kikuyu believed it was one of their “Ngai” God`s resting grounds. In 1884, Joseph Thompson a British explorer named it Aberdares. He, therefore, honoured Lord Aberdare, who by then was consequently President of the Royal Geographical Society and Royal Historical Society in Britain.
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, finally plunging into the Great Rift Valley. On the east, the range slopes more gently.
The Aberdares are the water catchment area for the Sasumua and the Ndakaini dam which provide Nairobi with water. The major rivers from Aberdare Forest are Tana and Athi, which flow into the India Ocean. Ewaso Nyiro that drains into Lorian Swamp and River Malewa that drains into Lake Naivasha. The ranges have several tributaries draining to the rivers. Higher up are several bogs, 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. River Tana is the largest river in Kenya, supplying water to the Seven Forks hydroelectric power complex. The hydro plant generates over 55% of Kenya’s total electricity output.
Aberdare Ranges Forest is 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. It has a perimeter of 566km varying in attitude from 2000m on the forest boundary on the east side. The highest at 4,001m 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 District. It borders several administrative districts like Nyandarua, Laikipia, Nyeri, Murang`a and Kiambu. The range has a maximum elevation of 3,999 metres 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.
The vegetation varies with altitude. Rich alpine and sub-alpine flora, including species of Senecio spp, Lobelia spp, Erica spp, Helichrysum spp, and tussock grasses. Belts of Arundinaria alpine bamboo, montane rainforest (mainly Juniperus procerus-Podocarpus falcatus-Nuxia on the western and northwestern slopes, Ocotea on the south-east, and mixed Podocarpus latifolius on the east and on Kipipiri. Pockets of Hagenia forest occur in sheltered patches on the rolling moorland.
The National Park lies mainly above the tree line, with some forest and scrub at lower altitude in the salient near Nyeri. The Aberdares Forest Reserve (103,300 ha) occupies the lower slopes, in three main blocks that almost surround the Park, with Kipipiri Forest Reserve (5,100 ha) tacked on to the west. The southern boundary of the Aberdares Forest Reserve adjoins the Kikuyu Escarpment Forest. The Aberdares are an extremely important water catchment for the Tana River system, for the northern Ewaso Nyiro River and for Lake Naivasha, and provide much of the water supply for Nairobi and adjoining districts.